1 | NAME |
1 | NAME |
2 | IO::AIO - Asynchronous Input/Output |
2 | IO::AIO - Asynchronous/Advanced Input/Output |
3 | |
3 | |
4 | SYNOPSIS |
4 | SYNOPSIS |
5 | use IO::AIO; |
5 | use IO::AIO; |
6 | |
6 | |
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7 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
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8 | my $fh = shift |
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9 | or die "/etc/passwd: $!"; |
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10 | ... |
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11 | }; |
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12 | |
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13 | aio_unlink "/tmp/file", sub { }; |
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14 | |
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15 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
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16 | $_[0] > 0 or die "read error: $!"; |
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17 | }; |
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18 | |
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19 | # version 2+ has request and group objects |
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20 | use IO::AIO 2; |
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21 | |
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22 | aioreq_pri 4; # give next request a very high priority |
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23 | my $req = aio_unlink "/tmp/file", sub { }; |
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24 | $req->cancel; # cancel request if still in queue |
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25 | |
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26 | my $grp = aio_group sub { print "all stats done\n" }; |
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27 | add $grp aio_stat "..." for ...; |
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28 | |
7 | DESCRIPTION |
29 | DESCRIPTION |
8 | This module implements asynchronous I/O using whatever means your |
30 | This module implements asynchronous I/O using whatever means your |
9 | operating system supports. |
31 | operating system supports. It is implemented as an interface to "libeio" |
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32 | (<http://software.schmorp.de/pkg/libeio.html>). |
10 | |
33 | |
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34 | Asynchronous means that operations that can normally block your program |
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35 | (e.g. reading from disk) will be done asynchronously: the operation will |
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36 | still block, but you can do something else in the meantime. This is |
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37 | extremely useful for programs that need to stay interactive even when |
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38 | doing heavy I/O (GUI programs, high performance network servers etc.), |
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39 | but can also be used to easily do operations in parallel that are |
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40 | normally done sequentially, e.g. stat'ing many files, which is much |
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41 | faster on a RAID volume or over NFS when you do a number of stat |
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42 | operations concurrently. |
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43 | |
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44 | While most of this works on all types of file descriptors (for example |
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45 | sockets), using these functions on file descriptors that support |
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46 | nonblocking operation (again, sockets, pipes etc.) is very inefficient. |
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47 | Use an event loop for that (such as the EV module): IO::AIO will |
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48 | naturally fit into such an event loop itself. |
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49 | |
11 | Currently, a number of threads are started that execute your read/writes |
50 | In this version, a number of threads are started that execute your |
12 | and signal their completion. You don't need thread support in your libc |
51 | requests and signal their completion. You don't need thread support in |
13 | or perl, and the threads created by this module will not be visible to |
52 | perl, and the threads created by this module will not be visible to |
14 | the pthreads library. In the future, this module might make use of the |
53 | perl. In the future, this module might make use of the native aio |
15 | native aio functions available on many operating systems. However, they |
54 | functions available on many operating systems. However, they are often |
16 | are often not well-supported (Linux doesn't allow them on normal files |
55 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
17 | currently, for example), and they would only support aio_read and |
56 | files currently, for example), and they would only support aio_read and |
18 | aio_write, so the remaining functionality would have to be implemented |
57 | aio_write, so the remaining functionality would have to be implemented |
19 | using threads anyway. |
58 | using threads anyway. |
20 | |
59 | |
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60 | In addition to asynchronous I/O, this module also exports some rather |
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61 | arcane interfaces, such as "madvise" or linux's "splice" system call, |
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62 | which is why the "A" in "AIO" can also mean *advanced*. |
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63 | |
21 | Although the module will work with in the presence of other threads, it |
64 | Although the module will work in the presence of other (Perl-) threads, |
22 | is currently not reentrant, so use appropriate locking yourself. |
65 | it is currently not reentrant in any way, so use appropriate locking |
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66 | yourself, always call "poll_cb" from within the same thread, or never |
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67 | call "poll_cb" (or other "aio_" functions) recursively. |
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68 | |
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69 | EXAMPLE |
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70 | This is a simple example that uses the EV module and loads /etc/passwd |
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71 | asynchronously: |
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72 | |
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73 | use EV; |
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74 | use IO::AIO; |
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75 | |
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76 | # register the IO::AIO callback with EV |
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77 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
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78 | |
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79 | # queue the request to open /etc/passwd |
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80 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
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81 | my $fh = shift |
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82 | or die "error while opening: $!"; |
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83 | |
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84 | # stat'ing filehandles is generally non-blocking |
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85 | my $size = -s $fh; |
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86 | |
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87 | # queue a request to read the file |
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88 | my $contents; |
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89 | aio_read $fh, 0, $size, $contents, 0, sub { |
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90 | $_[0] == $size |
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91 | or die "short read: $!"; |
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92 | |
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93 | close $fh; |
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94 | |
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95 | # file contents now in $contents |
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96 | print $contents; |
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97 | |
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98 | # exit event loop and program |
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99 | EV::break; |
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100 | }; |
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101 | }; |
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102 | |
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103 | # possibly queue up other requests, or open GUI windows, |
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104 | # check for sockets etc. etc. |
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105 | |
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106 | # process events as long as there are some: |
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107 | EV::run; |
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108 | |
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109 | REQUEST ANATOMY AND LIFETIME |
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110 | Every "aio_*" function creates a request. which is a C data structure |
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111 | not directly visible to Perl. |
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112 | |
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113 | If called in non-void context, every request function returns a Perl |
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114 | object representing the request. In void context, nothing is returned, |
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115 | which saves a bit of memory. |
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116 | |
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117 | The perl object is a fairly standard ref-to-hash object. The hash |
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118 | contents are not used by IO::AIO so you are free to store anything you |
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119 | like in it. |
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120 | |
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121 | During their existance, aio requests travel through the following |
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122 | states, in order: |
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123 | |
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124 | ready |
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125 | Immediately after a request is created it is put into the ready |
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126 | state, waiting for a thread to execute it. |
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127 | |
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128 | execute |
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129 | A thread has accepted the request for processing and is currently |
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130 | executing it (e.g. blocking in read). |
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131 | |
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132 | pending |
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133 | The request has been executed and is waiting for result processing. |
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134 | |
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135 | While request submission and execution is fully asynchronous, result |
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136 | processing is not and relies on the perl interpreter calling |
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137 | "poll_cb" (or another function with the same effect). |
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138 | |
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139 | result |
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140 | The request results are processed synchronously by "poll_cb". |
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141 | |
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142 | The "poll_cb" function will process all outstanding aio requests by |
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143 | calling their callbacks, freeing memory associated with them and |
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144 | managing any groups they are contained in. |
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145 | |
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146 | done |
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147 | Request has reached the end of its lifetime and holds no resources |
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148 | anymore (except possibly for the Perl object, but its connection to |
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149 | the actual aio request is severed and calling its methods will |
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150 | either do nothing or result in a runtime error). |
23 | |
151 | |
24 | FUNCTIONS |
152 | FUNCTIONS |
25 | AIO FUNCTIONS |
153 | QUICK OVERVIEW |
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154 | This section simply lists the prototypes most of the functions for quick |
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155 | reference. See the following sections for function-by-function |
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156 | documentation. |
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157 | |
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158 | aio_wd $pathname, $callback->($wd) |
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159 | aio_open $pathname, $flags, $mode, $callback->($fh) |
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160 | aio_close $fh, $callback->($status) |
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161 | aio_seek $fh,$offset,$whence, $callback->($offs) |
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162 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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163 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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164 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
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165 | aio_readahead $fh,$offset,$length, $callback->($retval) |
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166 | aio_stat $fh_or_path, $callback->($status) |
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167 | aio_lstat $fh, $callback->($status) |
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168 | aio_statvfs $fh_or_path, $callback->($statvfs) |
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169 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
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170 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
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171 | aio_chmod $fh_or_path, $mode, $callback->($status) |
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172 | aio_truncate $fh_or_path, $offset, $callback->($status) |
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173 | aio_allocate $fh, $mode, $offset, $len, $callback->($status) |
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174 | aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) |
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175 | aio_unlink $pathname, $callback->($status) |
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176 | aio_mknod $pathname, $mode, $dev, $callback->($status) |
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177 | aio_link $srcpath, $dstpath, $callback->($status) |
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178 | aio_symlink $srcpath, $dstpath, $callback->($status) |
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179 | aio_readlink $pathname, $callback->($link) |
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180 | aio_realpath $pathname, $callback->($path) |
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181 | aio_rename $srcpath, $dstpath, $callback->($status) |
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182 | aio_rename2 $srcpath, $dstpath, $flags, $callback->($status) |
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183 | aio_mkdir $pathname, $mode, $callback->($status) |
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184 | aio_rmdir $pathname, $callback->($status) |
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185 | aio_readdir $pathname, $callback->($entries) |
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186 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
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187 | IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST |
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188 | IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN |
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189 | aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) |
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190 | aio_load $pathname, $data, $callback->($status) |
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191 | aio_copy $srcpath, $dstpath, $callback->($status) |
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192 | aio_move $srcpath, $dstpath, $callback->($status) |
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193 | aio_rmtree $pathname, $callback->($status) |
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194 | aio_fcntl $fh, $cmd, $arg, $callback->($status) |
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195 | aio_ioctl $fh, $request, $buf, $callback->($status) |
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196 | aio_sync $callback->($status) |
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197 | aio_syncfs $fh, $callback->($status) |
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198 | aio_fsync $fh, $callback->($status) |
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199 | aio_fdatasync $fh, $callback->($status) |
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200 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
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201 | aio_pathsync $pathname, $callback->($status) |
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202 | aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, $callback->($status) |
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203 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
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204 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
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205 | aio_mlockall $flags, $callback->($status) |
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206 | aio_group $callback->(...) |
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207 | aio_nop $callback->() |
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208 | |
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209 | $prev_pri = aioreq_pri [$pri] |
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210 | aioreq_nice $pri_adjust |
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211 | |
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212 | IO::AIO::poll_wait |
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213 | IO::AIO::poll_cb |
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214 | IO::AIO::poll |
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215 | IO::AIO::flush |
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216 | IO::AIO::max_poll_reqs $nreqs |
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217 | IO::AIO::max_poll_time $seconds |
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218 | IO::AIO::min_parallel $nthreads |
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219 | IO::AIO::max_parallel $nthreads |
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220 | IO::AIO::max_idle $nthreads |
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221 | IO::AIO::idle_timeout $seconds |
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222 | IO::AIO::max_outstanding $maxreqs |
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223 | IO::AIO::nreqs |
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224 | IO::AIO::nready |
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225 | IO::AIO::npending |
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226 | $nfd = IO::AIO::get_fdlimit [EXPERIMENTAL] |
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227 | IO::AIO::min_fdlimit $nfd [EXPERIMENTAL] |
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228 | |
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229 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
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230 | IO::AIO::fadvise $fh, $offset, $len, $advice |
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231 | IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] |
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232 | IO::AIO::munmap $scalar |
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233 | IO::AIO::mremap $scalar, $new_length, $flags[, $new_address] |
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234 | IO::AIO::madvise $scalar, $offset, $length, $advice |
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235 | IO::AIO::mprotect $scalar, $offset, $length, $protect |
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236 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
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237 | IO::AIO::munlockall |
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238 | |
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239 | API NOTES |
26 | All the "aio_*" calls are more or less thin wrappers around the syscall |
240 | All the "aio_*" calls are more or less thin wrappers around the syscall |
27 | with the same name (sans "aio_"). The arguments are similar or |
241 | with the same name (sans "aio_"). The arguments are similar or |
28 | identical, and they all accept an additional $callback argument which |
242 | identical, and they all accept an additional (and optional) $callback |
29 | must be a code reference. This code reference will get called with the |
243 | argument which must be a code reference. This code reference will be |
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244 | called after the syscall has been executed in an asynchronous fashion. |
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245 | The results of the request will be passed as arguments to the callback |
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246 | (and, if an error occured, in $!) - for most requests the syscall return |
30 | syscall return code (e.g. most syscalls return -1 on error, unlike perl, |
247 | code (e.g. most syscalls return -1 on error, unlike perl, which usually |
31 | which usually delivers "false") as it's sole argument when the given |
248 | delivers "false"). |
32 | syscall has been executed asynchronously. |
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33 | |
249 | |
34 | All functions that expect a filehandle will also accept a file |
250 | Some requests (such as "aio_readdir") pass the actual results and |
35 | descriptor. |
251 | communicate failures by passing "undef". |
36 | |
252 | |
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253 | All functions expecting a filehandle keep a copy of the filehandle |
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254 | internally until the request has finished. |
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255 | |
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256 | All functions return request objects of type IO::AIO::REQ that allow |
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257 | further manipulation of those requests while they are in-flight. |
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258 | |
37 | The filenames you pass to these routines *must* be absolute. The reason |
259 | The pathnames you pass to these routines *should* be absolute. The |
38 | is that at the time the request is being executed, the current working |
260 | reason for this is that at the time the request is being executed, the |
39 | directory could have changed. Alternatively, you can make sure that you |
261 | current working directory could have changed. Alternatively, you can |
40 | never change the current working directory. |
262 | make sure that you never change the current working directory anywhere |
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263 | in the program and then use relative paths. You can also take advantage |
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264 | of IO::AIOs working directory abstraction, that lets you specify paths |
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265 | relative to some previously-opened "working directory object" - see the |
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266 | description of the "IO::AIO::WD" class later in this document. |
41 | |
267 | |
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268 | To encode pathnames as octets, either make sure you either: a) always |
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269 | pass in filenames you got from outside (command line, readdir etc.) |
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270 | without tinkering, b) are in your native filesystem encoding, c) use the |
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271 | Encode module and encode your pathnames to the locale (or other) |
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272 | encoding in effect in the user environment, d) use |
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273 | Glib::filename_from_unicode on unicode filenames or e) use something |
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274 | else to ensure your scalar has the correct contents. |
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275 | |
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276 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
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277 | handles correctly whether it is set or not. |
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278 | |
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279 | AIO REQUEST FUNCTIONS |
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280 | $prev_pri = aioreq_pri [$pri] |
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281 | Returns the priority value that would be used for the next request |
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282 | and, if $pri is given, sets the priority for the next aio request. |
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283 | |
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284 | The default priority is 0, the minimum and maximum priorities are -4 |
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285 | and 4, respectively. Requests with higher priority will be serviced |
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286 | first. |
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287 | |
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288 | The priority will be reset to 0 after each call to one of the |
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289 | "aio_*" functions. |
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290 | |
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291 | Example: open a file with low priority, then read something from it |
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292 | with higher priority so the read request is serviced before other |
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293 | low priority open requests (potentially spamming the cache): |
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294 | |
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295 | aioreq_pri -3; |
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296 | aio_open ..., sub { |
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297 | return unless $_[0]; |
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298 | |
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299 | aioreq_pri -2; |
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300 | aio_read $_[0], ..., sub { |
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301 | ... |
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302 | }; |
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303 | }; |
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304 | |
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305 | aioreq_nice $pri_adjust |
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306 | Similar to "aioreq_pri", but subtracts the given value from the |
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307 | current priority, so the effect is cumulative. |
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308 | |
42 | aio_open $pathname, $flags, $mode, $callback |
309 | aio_open $pathname, $flags, $mode, $callback->($fh) |
43 | Asynchronously open or create a file and call the callback with a |
310 | Asynchronously open or create a file and call the callback with a |
44 | newly created filehandle for the file. |
311 | newly created filehandle for the file (or "undef" in case of an |
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312 | error). |
45 | |
313 | |
46 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
314 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
47 | above, for an explanation. |
315 | above, for an explanation. |
48 | |
316 | |
49 | The $mode argument is a bitmask. See the "Fcntl" module for a list. |
317 | The $flags argument is a bitmask. See the "Fcntl" module for a list. |
50 | They are the same as used in "sysopen". |
318 | They are the same as used by "sysopen". |
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319 | |
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320 | Likewise, $mode specifies the mode of the newly created file, if it |
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321 | didn't exist and "O_CREAT" has been given, just like perl's |
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322 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
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323 | create new files, and 0666 or 0777 if you do). Note that the $mode |
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324 | will be modified by the umask in effect then the request is being |
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325 | executed, so better never change the umask. |
51 | |
326 | |
52 | Example: |
327 | Example: |
53 | |
328 | |
54 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
329 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
55 | if ($_[0]) { |
330 | if ($_[0]) { |
56 | print "open successful, fh is $_[0]\n"; |
331 | print "open successful, fh is $_[0]\n"; |
57 | ... |
332 | ... |
58 | } else { |
333 | } else { |
59 | die "open failed: $!\n"; |
334 | die "open failed: $!\n"; |
60 | } |
335 | } |
61 | }; |
336 | }; |
62 | |
337 | |
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338 | In addition to all the common open modes/flags ("O_RDONLY", |
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339 | "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and |
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340 | "O_APPEND"), the following POSIX and non-POSIX constants are |
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341 | available (missing ones on your system are, as usual, 0): |
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342 | |
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343 | "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", |
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344 | "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", |
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345 | "O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", "O_TTY_INIT" |
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346 | and "O_ACCMODE". |
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347 | |
63 | aio_close $fh, $callback |
348 | aio_close $fh, $callback->($status) |
64 | Asynchronously close a file and call the callback with the result |
349 | Asynchronously close a file and call the callback with the result |
65 | code. *WARNING:* although accepted, you should not pass in a perl |
350 | code. |
66 | filehandle here, as perl will likely close the file descriptor |
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67 | itself when the filehandle is destroyed. Normally, you can safely |
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68 | call perls "close" or just let filehandles go out of scope. |
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69 | |
351 | |
|
|
352 | Unfortunately, you can't do this to perl. Perl *insists* very |
|
|
353 | strongly on closing the file descriptor associated with the |
|
|
354 | filehandle itself. |
|
|
355 | |
|
|
356 | Therefore, "aio_close" will not close the filehandle - instead it |
|
|
357 | will use dup2 to overwrite the file descriptor with the write-end of |
|
|
358 | a pipe (the pipe fd will be created on demand and will be cached). |
|
|
359 | |
|
|
360 | Or in other words: the file descriptor will be closed, but it will |
|
|
361 | not be free for reuse until the perl filehandle is closed. |
|
|
362 | |
|
|
363 | aio_seek $fh, $offset, $whence, $callback->($offs) |
|
|
364 | Seeks the filehandle to the new $offset, similarly to perl's |
|
|
365 | "sysseek". The $whence can use the traditional values (0 for |
|
|
366 | "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for |
|
|
367 | "IO::AIO::SEEK_END"). |
|
|
368 | |
|
|
369 | The resulting absolute offset will be passed to the callback, or -1 |
|
|
370 | in case of an error. |
|
|
371 | |
|
|
372 | In theory, the $whence constants could be different than the |
|
|
373 | corresponding values from Fcntl, but perl guarantees they are the |
|
|
374 | same, so don't panic. |
|
|
375 | |
|
|
376 | As a GNU/Linux (and maybe Solaris) extension, also the constants |
|
|
377 | "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they |
|
|
378 | could be found. No guarantees about suitability for use in |
|
|
379 | "aio_seek" or Perl's "sysseek" can be made though, although I would |
|
|
380 | naively assume they "just work". |
|
|
381 | |
70 | aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
382 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
71 | aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
383 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
72 | Reads or writes "length" bytes from the specified "fh" and "offset" |
384 | Reads or writes $length bytes from or to the specified $fh and |
73 | into the scalar given by "data" and offset "dataoffset" and calls |
385 | $offset into the scalar given by $data and offset $dataoffset and |
74 | the callback without the actual number of bytes read (or -1 on |
386 | calls the callback with the actual number of bytes transferred (or |
75 | error, just like the syscall). |
387 | -1 on error, just like the syscall). |
76 | |
388 | |
|
|
389 | "aio_read" will, like "sysread", shrink or grow the $data scalar to |
|
|
390 | offset plus the actual number of bytes read. |
|
|
391 | |
|
|
392 | If $offset is undefined, then the current file descriptor offset |
|
|
393 | will be used (and updated), otherwise the file descriptor offset |
|
|
394 | will not be changed by these calls. |
|
|
395 | |
|
|
396 | If $length is undefined in "aio_write", use the remaining length of |
|
|
397 | $data. |
|
|
398 | |
|
|
399 | If $dataoffset is less than zero, it will be counted from the end of |
|
|
400 | $data. |
|
|
401 | |
|
|
402 | The $data scalar *MUST NOT* be modified in any way while the request |
|
|
403 | is outstanding. Modifying it can result in segfaults or World War |
|
|
404 | III (if the necessary/optional hardware is installed). |
|
|
405 | |
77 | Example: Read 15 bytes at offset 7 into scalar $buffer, strating at |
406 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
78 | offset 0 within the scalar: |
407 | offset 0 within the scalar: |
79 | |
408 | |
80 | aio_read $fh, 7, 15, $buffer, 0, sub { |
409 | aio_read $fh, 7, 15, $buffer, 0, sub { |
81 | $_[0] >= 0 or die "read error: $!"; |
410 | $_[0] > 0 or die "read error: $!"; |
82 | print "read <$buffer>\n"; |
411 | print "read $_[0] bytes: <$buffer>\n"; |
83 | }; |
412 | }; |
84 | |
413 | |
|
|
414 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
|
|
415 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
|
|
416 | reading at byte offset $in_offset, and starts writing at the current |
|
|
417 | file offset of $out_fh. Because of that, it is not safe to issue |
|
|
418 | more than one "aio_sendfile" per $out_fh, as they will interfere |
|
|
419 | with each other. The same $in_fh works fine though, as this function |
|
|
420 | does not move or use the file offset of $in_fh. |
|
|
421 | |
|
|
422 | Please note that "aio_sendfile" can read more bytes from $in_fh than |
|
|
423 | are written, and there is no way to find out how many more bytes |
|
|
424 | have been read from "aio_sendfile" alone, as "aio_sendfile" only |
|
|
425 | provides the number of bytes written to $out_fh. Only if the result |
|
|
426 | value equals $length one can assume that $length bytes have been |
|
|
427 | read. |
|
|
428 | |
|
|
429 | Unlike with other "aio_" functions, it makes a lot of sense to use |
|
|
430 | "aio_sendfile" on non-blocking sockets, as long as one end |
|
|
431 | (typically the $in_fh) is a file - the file I/O will then be |
|
|
432 | asynchronous, while the socket I/O will be non-blocking. Note, |
|
|
433 | however, that you can run into a trap where "aio_sendfile" reads |
|
|
434 | some data with readahead, then fails to write all data, and when the |
|
|
435 | socket is ready the next time, the data in the cache is already |
|
|
436 | lost, forcing "aio_sendfile" to again hit the disk. Explicit |
|
|
437 | "aio_read" + "aio_write" let's you better control resource usage. |
|
|
438 | |
|
|
439 | This call tries to make use of a native "sendfile"-like syscall to |
|
|
440 | provide zero-copy operation. For this to work, $out_fh should refer |
|
|
441 | to a socket, and $in_fh should refer to an mmap'able file. |
|
|
442 | |
|
|
443 | If a native sendfile cannot be found or it fails with "ENOSYS", |
|
|
444 | "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or |
|
|
445 | "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on |
|
|
446 | any type of filehandle regardless of the limitations of the |
|
|
447 | operating system. |
|
|
448 | |
|
|
449 | As native sendfile syscalls (as practically any non-POSIX interface |
|
|
450 | hacked together in a hurry to improve benchmark numbers) tend to be |
|
|
451 | rather buggy on many systems, this implementation tries to work |
|
|
452 | around some known bugs in Linux and FreeBSD kernels (probably |
|
|
453 | others, too), but that might fail, so you really really should check |
|
|
454 | the return value of "aio_sendfile" - fewer bytes than expected might |
|
|
455 | have been transferred. |
|
|
456 | |
85 | aio_readahead $fh,$offset,$length, $callback |
457 | aio_readahead $fh,$offset,$length, $callback->($retval) |
86 | Asynchronously reads the specified byte range into the page cache, |
|
|
87 | using the "readahead" syscall. If that syscall doesn't exist the |
|
|
88 | status will be -1 and $! is set to ENOSYS. |
|
|
89 | |
|
|
90 | readahead() populates the page cache with data from a file so that |
458 | "aio_readahead" populates the page cache with data from a file so |
91 | subsequent reads from that file will not block on disk I/O. The |
459 | that subsequent reads from that file will not block on disk I/O. The |
92 | $offset argument specifies the starting point from which data is to |
460 | $offset argument specifies the starting point from which data is to |
93 | be read and $length specifies the number of bytes to be read. I/O is |
461 | be read and $length specifies the number of bytes to be read. I/O is |
94 | performed in whole pages, so that offset is effectively rounded down |
462 | performed in whole pages, so that offset is effectively rounded down |
95 | to a page boundary and bytes are read up to the next page boundary |
463 | to a page boundary and bytes are read up to the next page boundary |
96 | greater than or equal to (off-set+length). aio_readahead() does not |
464 | greater than or equal to (off-set+length). "aio_readahead" does not |
97 | read beyond the end of the file. The current file offset of the file |
465 | read beyond the end of the file. The current file offset of the file |
98 | is left unchanged. |
466 | is left unchanged. |
99 | |
467 | |
|
|
468 | If that syscall doesn't exist (likely if your kernel isn't Linux) it |
|
|
469 | will be emulated by simply reading the data, which would have a |
|
|
470 | similar effect. |
|
|
471 | |
100 | aio_stat $fh_or_path, $callback |
472 | aio_stat $fh_or_path, $callback->($status) |
101 | aio_lstat $fh, $callback |
473 | aio_lstat $fh, $callback->($status) |
102 | Works like perl's "stat" or "lstat" in void context. The callback |
474 | Works almost exactly like perl's "stat" or "lstat" in void context. |
103 | will be called after the stat and the results will be available |
475 | The callback will be called after the stat and the results will be |
104 | using "stat _" or "-s _" etc... |
476 | available using "stat _" or "-s _" and other tests (with the |
|
|
477 | exception of "-B" and "-T"). |
105 | |
478 | |
106 | The pathname passed to "aio_stat" must be absolute. See API NOTES, |
479 | The pathname passed to "aio_stat" must be absolute. See API NOTES, |
107 | above, for an explanation. |
480 | above, for an explanation. |
108 | |
481 | |
109 | Currently, the stats are always 64-bit-stats, i.e. instead of |
482 | Currently, the stats are always 64-bit-stats, i.e. instead of |
110 | returning an error when stat'ing a large file, the results will be |
483 | returning an error when stat'ing a large file, the results will be |
111 | silently truncated unless perl itself is compiled with large file |
484 | silently truncated unless perl itself is compiled with large file |
112 | support. |
485 | support. |
113 | |
486 | |
|
|
487 | To help interpret the mode and dev/rdev stat values, IO::AIO offers |
|
|
488 | the following constants and functions (if not implemented, the |
|
|
489 | constants will be 0 and the functions will either "croak" or fall |
|
|
490 | back on traditional behaviour). |
|
|
491 | |
|
|
492 | "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", |
|
|
493 | "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", |
|
|
494 | "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". |
|
|
495 | |
|
|
496 | To access higher resolution stat timestamps, see "SUBSECOND STAT |
|
|
497 | TIME ACCESS". |
|
|
498 | |
114 | Example: Print the length of /etc/passwd: |
499 | Example: Print the length of /etc/passwd: |
115 | |
500 | |
116 | aio_stat "/etc/passwd", sub { |
501 | aio_stat "/etc/passwd", sub { |
117 | $_[0] and die "stat failed: $!"; |
502 | $_[0] and die "stat failed: $!"; |
118 | print "size is ", -s _, "\n"; |
503 | print "size is ", -s _, "\n"; |
119 | }; |
504 | }; |
120 | |
505 | |
|
|
506 | aio_statvfs $fh_or_path, $callback->($statvfs) |
|
|
507 | Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on |
|
|
508 | whether a file handle or path was passed. |
|
|
509 | |
|
|
510 | On success, the callback is passed a hash reference with the |
|
|
511 | following members: "bsize", "frsize", "blocks", "bfree", "bavail", |
|
|
512 | "files", "ffree", "favail", "fsid", "flag" and "namemax". On |
|
|
513 | failure, "undef" is passed. |
|
|
514 | |
|
|
515 | The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY" |
|
|
516 | and "ST_NOSUID". |
|
|
517 | |
|
|
518 | The following non-POSIX IO::AIO::ST_* flag masks are defined to |
|
|
519 | their correct value when available, or to 0 on systems that do not |
|
|
520 | support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS", |
|
|
521 | "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE", |
|
|
522 | "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME". |
|
|
523 | |
|
|
524 | Example: stat "/wd" and dump out the data if successful. |
|
|
525 | |
|
|
526 | aio_statvfs "/wd", sub { |
|
|
527 | my $f = $_[0] |
|
|
528 | or die "statvfs: $!"; |
|
|
529 | |
|
|
530 | use Data::Dumper; |
|
|
531 | say Dumper $f; |
|
|
532 | }; |
|
|
533 | |
|
|
534 | # result: |
|
|
535 | { |
|
|
536 | bsize => 1024, |
|
|
537 | bfree => 4333064312, |
|
|
538 | blocks => 10253828096, |
|
|
539 | files => 2050765568, |
|
|
540 | flag => 4096, |
|
|
541 | favail => 2042092649, |
|
|
542 | bavail => 4333064312, |
|
|
543 | ffree => 2042092649, |
|
|
544 | namemax => 255, |
|
|
545 | frsize => 1024, |
|
|
546 | fsid => 1810 |
|
|
547 | } |
|
|
548 | |
|
|
549 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
|
|
550 | Works like perl's "utime" function (including the special case of |
|
|
551 | $atime and $mtime being undef). Fractional times are supported if |
|
|
552 | the underlying syscalls support them. |
|
|
553 | |
|
|
554 | When called with a pathname, uses utimensat(2) or utimes(2) if |
|
|
555 | available, otherwise utime(2). If called on a file descriptor, uses |
|
|
556 | futimens(2) or futimes(2) if available, otherwise returns ENOSYS, so |
|
|
557 | this is not portable. |
|
|
558 | |
|
|
559 | Examples: |
|
|
560 | |
|
|
561 | # set atime and mtime to current time (basically touch(1)): |
|
|
562 | aio_utime "path", undef, undef; |
|
|
563 | # set atime to current time and mtime to beginning of the epoch: |
|
|
564 | aio_utime "path", time, undef; # undef==0 |
|
|
565 | |
|
|
566 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
|
|
567 | Works like perl's "chown" function, except that "undef" for either |
|
|
568 | $uid or $gid is being interpreted as "do not change" (but -1 can |
|
|
569 | also be used). |
|
|
570 | |
|
|
571 | Examples: |
|
|
572 | |
|
|
573 | # same as "chown root path" in the shell: |
|
|
574 | aio_chown "path", 0, -1; |
|
|
575 | # same as above: |
|
|
576 | aio_chown "path", 0, undef; |
|
|
577 | |
|
|
578 | aio_truncate $fh_or_path, $offset, $callback->($status) |
|
|
579 | Works like truncate(2) or ftruncate(2). |
|
|
580 | |
|
|
581 | aio_allocate $fh, $mode, $offset, $len, $callback->($status) |
|
|
582 | Allocates or frees disk space according to the $mode argument. See |
|
|
583 | the linux "fallocate" documentation for details. |
|
|
584 | |
|
|
585 | $mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate |
|
|
586 | space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | |
|
|
587 | IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. |
|
|
588 | |
|
|
589 | IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range |
|
|
590 | (without leaving a hole), "FALLOC_FL_ZERO_RANGE", to zero a range, |
|
|
591 | "FALLOC_FL_INSERT_RANGE" to insert a range and |
|
|
592 | "FALLOC_FL_UNSHARE_RANGE" to unshare shared blocks (see your |
|
|
593 | fallocate(2) manpage). |
|
|
594 | |
|
|
595 | The file system block size used by "fallocate" is presumably the |
|
|
596 | "f_bsize" returned by "statvfs", but different filesystems and |
|
|
597 | filetypes can dictate other limitations. |
|
|
598 | |
|
|
599 | If "fallocate" isn't available or cannot be emulated (currently no |
|
|
600 | emulation will be attempted), passes -1 and sets $! to "ENOSYS". |
|
|
601 | |
|
|
602 | aio_chmod $fh_or_path, $mode, $callback->($status) |
|
|
603 | Works like perl's "chmod" function. |
|
|
604 | |
121 | aio_unlink $pathname, $callback |
605 | aio_unlink $pathname, $callback->($status) |
122 | Asynchronously unlink (delete) a file and call the callback with the |
606 | Asynchronously unlink (delete) a file and call the callback with the |
123 | result code. |
607 | result code. |
124 | |
608 | |
|
|
609 | aio_mknod $pathname, $mode, $dev, $callback->($status) |
|
|
610 | [EXPERIMENTAL] |
|
|
611 | |
|
|
612 | Asynchronously create a device node (or fifo). See mknod(2). |
|
|
613 | |
|
|
614 | The only (POSIX-) portable way of calling this function is: |
|
|
615 | |
|
|
616 | aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
|
|
617 | |
|
|
618 | See "aio_stat" for info about some potentially helpful extra |
|
|
619 | constants and functions. |
|
|
620 | |
|
|
621 | aio_link $srcpath, $dstpath, $callback->($status) |
|
|
622 | Asynchronously create a new link to the existing object at $srcpath |
|
|
623 | at the path $dstpath and call the callback with the result code. |
|
|
624 | |
|
|
625 | aio_symlink $srcpath, $dstpath, $callback->($status) |
|
|
626 | Asynchronously create a new symbolic link to the existing object at |
|
|
627 | $srcpath at the path $dstpath and call the callback with the result |
|
|
628 | code. |
|
|
629 | |
|
|
630 | aio_readlink $pathname, $callback->($link) |
|
|
631 | Asynchronously read the symlink specified by $path and pass it to |
|
|
632 | the callback. If an error occurs, nothing or undef gets passed to |
|
|
633 | the callback. |
|
|
634 | |
|
|
635 | aio_realpath $pathname, $callback->($path) |
|
|
636 | Asynchronously make the path absolute and resolve any symlinks in |
|
|
637 | $path. The resulting path only consists of directories (same as |
|
|
638 | Cwd::realpath). |
|
|
639 | |
|
|
640 | This request can be used to get the absolute path of the current |
|
|
641 | working directory by passing it a path of . (a single dot). |
|
|
642 | |
|
|
643 | aio_rename $srcpath, $dstpath, $callback->($status) |
|
|
644 | Asynchronously rename the object at $srcpath to $dstpath, just as |
|
|
645 | rename(2) and call the callback with the result code. |
|
|
646 | |
|
|
647 | On systems that support the AIO::WD working directory abstraction |
|
|
648 | natively, the case "[$wd, "."]" as $srcpath is specialcased - |
|
|
649 | instead of failing, "rename" is called on the absolute path of $wd. |
|
|
650 | |
|
|
651 | aio_rename2 $srcpath, $dstpath, $flags, $callback->($status) |
|
|
652 | Basically a version of "aio_rename" with an additional $flags |
|
|
653 | argument. Calling this with "$flags=0" is the same as calling |
|
|
654 | "aio_rename". |
|
|
655 | |
|
|
656 | Non-zero flags are currently only supported on GNU/Linux systems |
|
|
657 | that support renameat2. Other systems fail with "ENOSYS" in this |
|
|
658 | case. |
|
|
659 | |
|
|
660 | The following constants are available (missing ones are, as usual |
|
|
661 | 0), see renameat2(2) for details: |
|
|
662 | |
|
|
663 | "IO::AIO::RENAME_NOREPLACE", "IO::AIO::RENAME_EXCHANGE" and |
|
|
664 | "IO::AIO::RENAME_WHITEOUT". |
|
|
665 | |
|
|
666 | aio_mkdir $pathname, $mode, $callback->($status) |
|
|
667 | Asynchronously mkdir (create) a directory and call the callback with |
|
|
668 | the result code. $mode will be modified by the umask at the time the |
|
|
669 | request is executed, so do not change your umask. |
|
|
670 | |
|
|
671 | aio_rmdir $pathname, $callback->($status) |
|
|
672 | Asynchronously rmdir (delete) a directory and call the callback with |
|
|
673 | the result code. |
|
|
674 | |
|
|
675 | On systems that support the AIO::WD working directory abstraction |
|
|
676 | natively, the case "[$wd, "."]" is specialcased - instead of |
|
|
677 | failing, "rmdir" is called on the absolute path of $wd. |
|
|
678 | |
|
|
679 | aio_readdir $pathname, $callback->($entries) |
|
|
680 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
|
|
681 | entire directory (i.e. opendir + readdir + closedir). The entries |
|
|
682 | will not be sorted, and will NOT include the "." and ".." entries. |
|
|
683 | |
|
|
684 | The callback is passed a single argument which is either "undef" or |
|
|
685 | an array-ref with the filenames. |
|
|
686 | |
|
|
687 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
|
|
688 | Quite similar to "aio_readdir", but the $flags argument allows one |
|
|
689 | to tune behaviour and output format. In case of an error, $entries |
|
|
690 | will be "undef". |
|
|
691 | |
|
|
692 | The flags are a combination of the following constants, ORed |
|
|
693 | together (the flags will also be passed to the callback, possibly |
|
|
694 | modified): |
|
|
695 | |
|
|
696 | IO::AIO::READDIR_DENTS |
|
|
697 | Normally the callback gets an arrayref consisting of names only |
|
|
698 | (as with "aio_readdir"). If this flag is set, then the callback |
|
|
699 | gets an arrayref with "[$name, $type, $inode]" arrayrefs, each |
|
|
700 | describing a single directory entry in more detail: |
|
|
701 | |
|
|
702 | $name is the name of the entry. |
|
|
703 | |
|
|
704 | $type is one of the "IO::AIO::DT_xxx" constants: |
|
|
705 | |
|
|
706 | "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", |
|
|
707 | "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", |
|
|
708 | "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". |
|
|
709 | |
|
|
710 | "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If |
|
|
711 | you need to know, you have to run stat yourself. Also, for |
|
|
712 | speed/memory reasons, the $type scalars are read-only: you must |
|
|
713 | not modify them. |
|
|
714 | |
|
|
715 | $inode is the inode number (which might not be exact on systems |
|
|
716 | with 64 bit inode numbers and 32 bit perls). This field has |
|
|
717 | unspecified content on systems that do not deliver the inode |
|
|
718 | information. |
|
|
719 | |
|
|
720 | IO::AIO::READDIR_DIRS_FIRST |
|
|
721 | When this flag is set, then the names will be returned in an |
|
|
722 | order where likely directories come first, in optimal stat |
|
|
723 | order. This is useful when you need to quickly find directories, |
|
|
724 | or you want to find all directories while avoiding to stat() |
|
|
725 | each entry. |
|
|
726 | |
|
|
727 | If the system returns type information in readdir, then this is |
|
|
728 | used to find directories directly. Otherwise, likely directories |
|
|
729 | are names beginning with ".", or otherwise names with no dots, |
|
|
730 | of which names with short names are tried first. |
|
|
731 | |
|
|
732 | IO::AIO::READDIR_STAT_ORDER |
|
|
733 | When this flag is set, then the names will be returned in an |
|
|
734 | order suitable for stat()'ing each one. That is, when you plan |
|
|
735 | to stat() most or all files in the given directory, then the |
|
|
736 | returned order will likely be faster. |
|
|
737 | |
|
|
738 | If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are |
|
|
739 | specified, then the likely dirs come first, resulting in a less |
|
|
740 | optimal stat order for stat'ing all entries, but likely a more |
|
|
741 | optimal order for finding subdirectories. |
|
|
742 | |
|
|
743 | IO::AIO::READDIR_FOUND_UNKNOWN |
|
|
744 | This flag should not be set when calling "aio_readdirx". |
|
|
745 | Instead, it is being set by "aio_readdirx", when any of the |
|
|
746 | $type's found were "IO::AIO::DT_UNKNOWN". The absence of this |
|
|
747 | flag therefore indicates that all $type's are known, which can |
|
|
748 | be used to speed up some algorithms. |
|
|
749 | |
|
|
750 | aio_slurp $pathname, $offset, $length, $data, $callback->($status) |
|
|
751 | Opens, reads and closes the given file. The data is put into $data, |
|
|
752 | which is resized as required. |
|
|
753 | |
|
|
754 | If $offset is negative, then it is counted from the end of the file. |
|
|
755 | |
|
|
756 | If $length is zero, then the remaining length of the file is used. |
|
|
757 | Also, in this case, the same limitations to modifying $data apply as |
|
|
758 | when IO::AIO::mmap is used, i.e. it must only be modified in-place |
|
|
759 | with "substr". If the size of the file is known, specifying a |
|
|
760 | non-zero $length results in a performance advantage. |
|
|
761 | |
|
|
762 | This request is similar to the older "aio_load" request, but since |
|
|
763 | it is a single request, it might be more efficient to use. |
|
|
764 | |
|
|
765 | Example: load /etc/passwd into $passwd. |
|
|
766 | |
|
|
767 | my $passwd; |
|
|
768 | aio_slurp "/etc/passwd", 0, 0, $passwd, sub { |
|
|
769 | $_[0] >= 0 |
|
|
770 | or die "/etc/passwd: $!\n"; |
|
|
771 | |
|
|
772 | printf "/etc/passwd is %d bytes long, and contains:\n", length $passwd; |
|
|
773 | print $passwd; |
|
|
774 | }; |
|
|
775 | IO::AIO::flush; |
|
|
776 | |
|
|
777 | aio_load $pathname, $data, $callback->($status) |
|
|
778 | This is a composite request that tries to fully load the given file |
|
|
779 | into memory. Status is the same as with aio_read. |
|
|
780 | |
|
|
781 | Using "aio_slurp" might be more efficient, as it is a single |
|
|
782 | request. |
|
|
783 | |
|
|
784 | aio_copy $srcpath, $dstpath, $callback->($status) |
|
|
785 | Try to copy the *file* (directories not supported as either source |
|
|
786 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
787 | a status of 0 (ok) or -1 (error, see $!). |
|
|
788 | |
|
|
789 | Existing destination files will be truncated. |
|
|
790 | |
|
|
791 | This is a composite request that creates the destination file with |
|
|
792 | mode 0200 and copies the contents of the source file into it using |
|
|
793 | "aio_sendfile", followed by restoring atime, mtime, access mode and |
|
|
794 | uid/gid, in that order. |
|
|
795 | |
|
|
796 | If an error occurs, the partial destination file will be unlinked, |
|
|
797 | if possible, except when setting atime, mtime, access mode and |
|
|
798 | uid/gid, where errors are being ignored. |
|
|
799 | |
|
|
800 | aio_move $srcpath, $dstpath, $callback->($status) |
|
|
801 | Try to move the *file* (directories not supported as either source |
|
|
802 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
803 | a status of 0 (ok) or -1 (error, see $!). |
|
|
804 | |
|
|
805 | This is a composite request that tries to rename(2) the file first; |
|
|
806 | if rename fails with "EXDEV", it copies the file with "aio_copy" |
|
|
807 | and, if that is successful, unlinks the $srcpath. |
|
|
808 | |
|
|
809 | aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) |
|
|
810 | Scans a directory (similar to "aio_readdir") but additionally tries |
|
|
811 | to efficiently separate the entries of directory $path into two sets |
|
|
812 | of names, directories you can recurse into (directories), and ones |
|
|
813 | you cannot recurse into (everything else, including symlinks to |
|
|
814 | directories). |
|
|
815 | |
|
|
816 | "aio_scandir" is a composite request that generates many sub |
|
|
817 | requests. $maxreq specifies the maximum number of outstanding aio |
|
|
818 | requests that this function generates. If it is "<= 0", then a |
|
|
819 | suitable default will be chosen (currently 4). |
|
|
820 | |
|
|
821 | On error, the callback is called without arguments, otherwise it |
|
|
822 | receives two array-refs with path-relative entry names. |
|
|
823 | |
|
|
824 | Example: |
|
|
825 | |
|
|
826 | aio_scandir $dir, 0, sub { |
|
|
827 | my ($dirs, $nondirs) = @_; |
|
|
828 | print "real directories: @$dirs\n"; |
|
|
829 | print "everything else: @$nondirs\n"; |
|
|
830 | }; |
|
|
831 | |
|
|
832 | Implementation notes. |
|
|
833 | |
|
|
834 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
|
|
835 | can. |
|
|
836 | |
|
|
837 | If readdir returns file type information, then this is used directly |
|
|
838 | to find directories. |
|
|
839 | |
|
|
840 | Otherwise, after reading the directory, the modification time, size |
|
|
841 | etc. of the directory before and after the readdir is checked, and |
|
|
842 | if they match (and isn't the current time), the link count will be |
|
|
843 | used to decide how many entries are directories (if >= 2). |
|
|
844 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
845 | assumed. |
|
|
846 | |
|
|
847 | Then entries will be sorted into likely directories a non-initial |
|
|
848 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
|
|
849 | every entry plus an appended "/." will be "stat"'ed, likely |
|
|
850 | directories first, in order of their inode numbers. If that |
|
|
851 | succeeds, it assumes that the entry is a directory or a symlink to |
|
|
852 | directory (which will be checked separately). This is often faster |
|
|
853 | than stat'ing the entry itself because filesystems might detect the |
|
|
854 | type of the entry without reading the inode data (e.g. ext2fs |
|
|
855 | filetype feature), even on systems that cannot return the filetype |
|
|
856 | information on readdir. |
|
|
857 | |
|
|
858 | If the known number of directories (link count - 2) has been |
|
|
859 | reached, the rest of the entries is assumed to be non-directories. |
|
|
860 | |
|
|
861 | This only works with certainty on POSIX (= UNIX) filesystems, which |
|
|
862 | fortunately are the vast majority of filesystems around. |
|
|
863 | |
|
|
864 | It will also likely work on non-POSIX filesystems with reduced |
|
|
865 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
866 | disables the directory counting heuristic. |
|
|
867 | |
|
|
868 | aio_rmtree $pathname, $callback->($status) |
|
|
869 | Delete a directory tree starting (and including) $path, return the |
|
|
870 | status of the final "rmdir" only. This is a composite request that |
|
|
871 | uses "aio_scandir" to recurse into and rmdir directories, and unlink |
|
|
872 | everything else. |
|
|
873 | |
|
|
874 | aio_fcntl $fh, $cmd, $arg, $callback->($status) |
|
|
875 | aio_ioctl $fh, $request, $buf, $callback->($status) |
|
|
876 | These work just like the "fcntl" and "ioctl" built-in functions, |
|
|
877 | except they execute asynchronously and pass the return value to the |
|
|
878 | callback. |
|
|
879 | |
|
|
880 | Both calls can be used for a lot of things, some of which make more |
|
|
881 | sense to run asynchronously in their own thread, while some others |
|
|
882 | make less sense. For example, calls that block waiting for external |
|
|
883 | events, such as locking, will also lock down an I/O thread while it |
|
|
884 | is waiting, which can deadlock the whole I/O system. At the same |
|
|
885 | time, there might be no alternative to using a thread to wait. |
|
|
886 | |
|
|
887 | So in general, you should only use these calls for things that do |
|
|
888 | (filesystem) I/O, not for things that wait for other events |
|
|
889 | (network, other processes), although if you are careful and know |
|
|
890 | what you are doing, you still can. |
|
|
891 | |
|
|
892 | The following constants are available (missing ones are, as usual |
|
|
893 | 0): |
|
|
894 | |
|
|
895 | "F_DUPFD_CLOEXEC", |
|
|
896 | |
|
|
897 | "F_OFD_GETLK", "F_OFD_SETLK", "F_OFD_GETLKW", |
|
|
898 | |
|
|
899 | "FIFREEZE", "FITHAW", "FITRIM", "FICLONE", "FICLONERANGE", |
|
|
900 | "FIDEDUPERANGE". |
|
|
901 | |
|
|
902 | "FS_IOC_GETFLAGS", "FS_IOC_SETFLAGS", "FS_IOC_GETVERSION", |
|
|
903 | "FS_IOC_SETVERSION", "FS_IOC_FIEMAP". |
|
|
904 | |
|
|
905 | "FS_IOC_FSGETXATTR", "FS_IOC_FSSETXATTR", |
|
|
906 | "FS_IOC_SET_ENCRYPTION_POLICY", "FS_IOC_GET_ENCRYPTION_PWSALT", |
|
|
907 | "FS_IOC_GET_ENCRYPTION_POLICY", "FS_KEY_DESCRIPTOR_SIZE". |
|
|
908 | |
|
|
909 | "FS_SECRM_FL", "FS_UNRM_FL", "FS_COMPR_FL", "FS_SYNC_FL", |
|
|
910 | "FS_IMMUTABLE_FL", "FS_APPEND_FL", "FS_NODUMP_FL", "FS_NOATIME_FL", |
|
|
911 | "FS_DIRTY_FL", "FS_COMPRBLK_FL", "FS_NOCOMP_FL", "FS_ENCRYPT_FL", |
|
|
912 | "FS_BTREE_FL", "FS_INDEX_FL", "FS_JOURNAL_DATA_FL", "FS_NOTAIL_FL", |
|
|
913 | "FS_DIRSYNC_FL", "FS_TOPDIR_FL", "FS_FL_USER_MODIFIABLE". |
|
|
914 | |
|
|
915 | "FS_XFLAG_REALTIME", "FS_XFLAG_PREALLOC", "FS_XFLAG_IMMUTABLE", |
|
|
916 | "FS_XFLAG_APPEND", "FS_XFLAG_SYNC", "FS_XFLAG_NOATIME", |
|
|
917 | "FS_XFLAG_NODUMP", "FS_XFLAG_RTINHERIT", "FS_XFLAG_PROJINHERIT", |
|
|
918 | "FS_XFLAG_NOSYMLINKS", "FS_XFLAG_EXTSIZE", "FS_XFLAG_EXTSZINHERIT", |
|
|
919 | "FS_XFLAG_NODEFRAG", "FS_XFLAG_FILESTREAM", "FS_XFLAG_DAX", |
|
|
920 | "FS_XFLAG_HASATTR", |
|
|
921 | |
|
|
922 | aio_sync $callback->($status) |
|
|
923 | Asynchronously call sync and call the callback when finished. |
|
|
924 | |
125 | aio_fsync $fh, $callback |
925 | aio_fsync $fh, $callback->($status) |
126 | Asynchronously call fsync on the given filehandle and call the |
926 | Asynchronously call fsync on the given filehandle and call the |
127 | callback with the fsync result code. |
927 | callback with the fsync result code. |
128 | |
928 | |
129 | aio_fdatasync $fh, $callback |
929 | aio_fdatasync $fh, $callback->($status) |
130 | Asynchronously call fdatasync on the given filehandle and call the |
930 | Asynchronously call fdatasync on the given filehandle and call the |
131 | callback with the fdatasync result code. |
931 | callback with the fdatasync result code. |
132 | |
932 | |
|
|
933 | If this call isn't available because your OS lacks it or it couldn't |
|
|
934 | be detected, it will be emulated by calling "fsync" instead. |
|
|
935 | |
|
|
936 | aio_syncfs $fh, $callback->($status) |
|
|
937 | Asynchronously call the syncfs syscall to sync the filesystem |
|
|
938 | associated to the given filehandle and call the callback with the |
|
|
939 | syncfs result code. If syncfs is not available, calls sync(), but |
|
|
940 | returns -1 and sets errno to "ENOSYS" nevertheless. |
|
|
941 | |
|
|
942 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
|
|
943 | Sync the data portion of the file specified by $offset and $length |
|
|
944 | to disk (but NOT the metadata), by calling the Linux-specific |
|
|
945 | sync_file_range call. If sync_file_range is not available or it |
|
|
946 | returns ENOSYS, then fdatasync or fsync is being substituted. |
|
|
947 | |
|
|
948 | $flags can be a combination of |
|
|
949 | "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", |
|
|
950 | "IO::AIO::SYNC_FILE_RANGE_WRITE" and |
|
|
951 | "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range |
|
|
952 | manpage for details. |
|
|
953 | |
|
|
954 | aio_pathsync $pathname, $callback->($status) |
|
|
955 | This request tries to open, fsync and close the given path. This is |
|
|
956 | a composite request intended to sync directories after directory |
|
|
957 | operations (E.g. rename). This might not work on all operating |
|
|
958 | systems or have any specific effect, but usually it makes sure that |
|
|
959 | directory changes get written to disc. It works for anything that |
|
|
960 | can be opened for read-only, not just directories. |
|
|
961 | |
|
|
962 | Future versions of this function might fall back to other methods |
|
|
963 | when "fsync" on the directory fails (such as calling "sync"). |
|
|
964 | |
|
|
965 | Passes 0 when everything went ok, and -1 on error. |
|
|
966 | |
|
|
967 | aio_msync $scalar, $offset = 0, $length = undef, flags = MS_SYNC, |
|
|
968 | $callback->($status) |
|
|
969 | This is a rather advanced IO::AIO call, which only works on |
|
|
970 | mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it |
|
|
971 | also works on data scalars managed by the Sys::Mmap or Mmap modules, |
|
|
972 | note that the scalar must only be modified in-place while an aio |
|
|
973 | operation is pending on it). |
|
|
974 | |
|
|
975 | It calls the "msync" function of your OS, if available, with the |
|
|
976 | memory area starting at $offset in the string and ending $length |
|
|
977 | bytes later. If $length is negative, counts from the end, and if |
|
|
978 | $length is "undef", then it goes till the end of the string. The |
|
|
979 | flags can be either "IO::AIO::MS_ASYNC" or "IO::AIO::MS_SYNC", plus |
|
|
980 | an optional "IO::AIO::MS_INVALIDATE". |
|
|
981 | |
|
|
982 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
983 | $callback->($status) |
|
|
984 | This is a rather advanced IO::AIO call, which works best on |
|
|
985 | mmap(2)ed scalars. |
|
|
986 | |
|
|
987 | It touches (reads or writes) all memory pages in the specified range |
|
|
988 | inside the scalar. All caveats and parameters are the same as for |
|
|
989 | "aio_msync", above, except for flags, which must be either 0 (which |
|
|
990 | reads all pages and ensures they are instantiated) or |
|
|
991 | "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading |
|
|
992 | and writing an octet from it, which dirties the page). |
|
|
993 | |
|
|
994 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
|
|
995 | This is a rather advanced IO::AIO call, which works best on |
|
|
996 | mmap(2)ed scalars. |
|
|
997 | |
|
|
998 | It reads in all the pages of the underlying storage into memory (if |
|
|
999 | any) and locks them, so they are not getting swapped/paged out or |
|
|
1000 | removed. |
|
|
1001 | |
|
|
1002 | If $length is undefined, then the scalar will be locked till the |
|
|
1003 | end. |
|
|
1004 | |
|
|
1005 | On systems that do not implement "mlock", this function returns -1 |
|
|
1006 | and sets errno to "ENOSYS". |
|
|
1007 | |
|
|
1008 | Note that the corresponding "munlock" is synchronous and is |
|
|
1009 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
1010 | |
|
|
1011 | Example: open a file, mmap and mlock it - both will be undone when |
|
|
1012 | $data gets destroyed. |
|
|
1013 | |
|
|
1014 | open my $fh, "<", $path or die "$path: $!"; |
|
|
1015 | my $data; |
|
|
1016 | IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
|
|
1017 | aio_mlock $data; # mlock in background |
|
|
1018 | |
|
|
1019 | aio_mlockall $flags, $callback->($status) |
|
|
1020 | Calls the "mlockall" function with the given $flags (a combination |
|
|
1021 | of "IO::AIO::MCL_CURRENT", "IO::AIO::MCL_FUTURE" and |
|
|
1022 | "IO::AIO::MCL_ONFAULT"). |
|
|
1023 | |
|
|
1024 | On systems that do not implement "mlockall", this function returns |
|
|
1025 | -1 and sets errno to "ENOSYS". Similarly, flag combinations not |
|
|
1026 | supported by the system result in a return value of -1 with errno |
|
|
1027 | being set to "EINVAL". |
|
|
1028 | |
|
|
1029 | Note that the corresponding "munlockall" is synchronous and is |
|
|
1030 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
1031 | |
|
|
1032 | Example: asynchronously lock all current and future pages into |
|
|
1033 | memory. |
|
|
1034 | |
|
|
1035 | aio_mlockall IO::AIO::MCL_FUTURE; |
|
|
1036 | |
|
|
1037 | aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) |
|
|
1038 | Queries the extents of the given file (by calling the Linux "FIEMAP" |
|
|
1039 | ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for |
|
|
1040 | details). If the ioctl is not available on your OS, then this |
|
|
1041 | request will fail with "ENOSYS". |
|
|
1042 | |
|
|
1043 | $start is the starting offset to query extents for, $length is the |
|
|
1044 | size of the range to query - if it is "undef", then the whole file |
|
|
1045 | will be queried. |
|
|
1046 | |
|
|
1047 | $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or |
|
|
1048 | "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is |
|
|
1049 | also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to |
|
|
1050 | query the data portion. |
|
|
1051 | |
|
|
1052 | $count is the maximum number of extent records to return. If it is |
|
|
1053 | "undef", then IO::AIO queries all extents of the range. As a very |
|
|
1054 | special case, if it is 0, then the callback receives the number of |
|
|
1055 | extents instead of the extents themselves (which is unreliable, see |
|
|
1056 | below). |
|
|
1057 | |
|
|
1058 | If an error occurs, the callback receives no arguments. The special |
|
|
1059 | "errno" value "IO::AIO::EBADR" is available to test for flag errors. |
|
|
1060 | |
|
|
1061 | Otherwise, the callback receives an array reference with extent |
|
|
1062 | structures. Each extent structure is an array reference itself, with |
|
|
1063 | the following members: |
|
|
1064 | |
|
|
1065 | [$logical, $physical, $length, $flags] |
|
|
1066 | |
|
|
1067 | Flags is any combination of the following flag values (typically |
|
|
1068 | either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)): |
|
|
1069 | |
|
|
1070 | "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN", |
|
|
1071 | "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED", |
|
|
1072 | "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED", |
|
|
1073 | "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED", |
|
|
1074 | "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", |
|
|
1075 | "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", |
|
|
1076 | "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" |
|
|
1077 | or "IO::AIO::FIEMAP_EXTENT_SHARED". |
|
|
1078 | |
|
|
1079 | At the time of this writing (Linux 3.2), this request is unreliable |
|
|
1080 | unless $count is "undef", as the kernel has all sorts of bugs |
|
|
1081 | preventing it to return all extents of a range for files with a |
|
|
1082 | large number of extents. The code (only) works around all these |
|
|
1083 | issues if $count is "undef". |
|
|
1084 | |
|
|
1085 | aio_group $callback->(...) |
|
|
1086 | This is a very special aio request: Instead of doing something, it |
|
|
1087 | is a container for other aio requests, which is useful if you want |
|
|
1088 | to bundle many requests into a single, composite, request with a |
|
|
1089 | definite callback and the ability to cancel the whole request with |
|
|
1090 | its subrequests. |
|
|
1091 | |
|
|
1092 | Returns an object of class IO::AIO::GRP. See its documentation below |
|
|
1093 | for more info. |
|
|
1094 | |
|
|
1095 | Example: |
|
|
1096 | |
|
|
1097 | my $grp = aio_group sub { |
|
|
1098 | print "all stats done\n"; |
|
|
1099 | }; |
|
|
1100 | |
|
|
1101 | add $grp |
|
|
1102 | (aio_stat ...), |
|
|
1103 | (aio_stat ...), |
|
|
1104 | ...; |
|
|
1105 | |
|
|
1106 | aio_nop $callback->() |
|
|
1107 | This is a special request - it does nothing in itself and is only |
|
|
1108 | used for side effects, such as when you want to add a dummy request |
|
|
1109 | to a group so that finishing the requests in the group depends on |
|
|
1110 | executing the given code. |
|
|
1111 | |
|
|
1112 | While this request does nothing, it still goes through the execution |
|
|
1113 | phase and still requires a worker thread. Thus, the callback will |
|
|
1114 | not be executed immediately but only after other requests in the |
|
|
1115 | queue have entered their execution phase. This can be used to |
|
|
1116 | measure request latency. |
|
|
1117 | |
|
|
1118 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
|
|
1119 | Mainly used for debugging and benchmarking, this aio request puts |
|
|
1120 | one of the request workers to sleep for the given time. |
|
|
1121 | |
|
|
1122 | While it is theoretically handy to have simple I/O scheduling |
|
|
1123 | requests like sleep and file handle readable/writable, the overhead |
|
|
1124 | this creates is immense (it blocks a thread for a long time) so do |
|
|
1125 | not use this function except to put your application under |
|
|
1126 | artificial I/O pressure. |
|
|
1127 | |
|
|
1128 | IO::AIO::WD - multiple working directories |
|
|
1129 | Your process only has one current working directory, which is used by |
|
|
1130 | all threads. This makes it hard to use relative paths (some other |
|
|
1131 | component could call "chdir" at any time, and it is hard to control when |
|
|
1132 | the path will be used by IO::AIO). |
|
|
1133 | |
|
|
1134 | One solution for this is to always use absolute paths. This usually |
|
|
1135 | works, but can be quite slow (the kernel has to walk the whole path on |
|
|
1136 | every access), and can also be a hassle to implement. |
|
|
1137 | |
|
|
1138 | Newer POSIX systems have a number of functions (openat, fdopendir, |
|
|
1139 | futimensat and so on) that make it possible to specify working |
|
|
1140 | directories per operation. |
|
|
1141 | |
|
|
1142 | For portability, and because the clowns who "designed", or shall I |
|
|
1143 | write, perpetrated this new interface were obviously half-drunk, this |
|
|
1144 | abstraction cannot be perfect, though. |
|
|
1145 | |
|
|
1146 | IO::AIO allows you to convert directory paths into a so-called |
|
|
1147 | IO::AIO::WD object. This object stores the canonicalised, absolute |
|
|
1148 | version of the path, and on systems that allow it, also a directory file |
|
|
1149 | descriptor. |
|
|
1150 | |
|
|
1151 | Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat" |
|
|
1152 | or "aio_unlink"), one can specify an array reference with an IO::AIO::WD |
|
|
1153 | object and a pathname instead (or the IO::AIO::WD object alone, which |
|
|
1154 | gets interpreted as "[$wd, "."]"). If the pathname is absolute, the |
|
|
1155 | IO::AIO::WD object is ignored, otherwise the pathname is resolved |
|
|
1156 | relative to that IO::AIO::WD object. |
|
|
1157 | |
|
|
1158 | For example, to get a wd object for /etc and then stat passwd inside, |
|
|
1159 | you would write: |
|
|
1160 | |
|
|
1161 | aio_wd "/etc", sub { |
|
|
1162 | my $etcdir = shift; |
|
|
1163 | |
|
|
1164 | # although $etcdir can be undef on error, there is generally no reason |
|
|
1165 | # to check for errors here, as aio_stat will fail with ENOENT |
|
|
1166 | # when $etcdir is undef. |
|
|
1167 | |
|
|
1168 | aio_stat [$etcdir, "passwd"], sub { |
|
|
1169 | # yay |
|
|
1170 | }; |
|
|
1171 | }; |
|
|
1172 | |
|
|
1173 | The fact that "aio_wd" is a request and not a normal function shows that |
|
|
1174 | creating an IO::AIO::WD object is itself a potentially blocking |
|
|
1175 | operation, which is why it is done asynchronously. |
|
|
1176 | |
|
|
1177 | To stat the directory obtained with "aio_wd" above, one could write |
|
|
1178 | either of the following three request calls: |
|
|
1179 | |
|
|
1180 | aio_lstat "/etc" , sub { ... # pathname as normal string |
|
|
1181 | aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself) |
|
|
1182 | aio_lstat $wd , sub { ... # shorthand for the previous |
|
|
1183 | |
|
|
1184 | As with normal pathnames, IO::AIO keeps a copy of the working directory |
|
|
1185 | object and the pathname string, so you could write the following without |
|
|
1186 | causing any issues due to $path getting reused: |
|
|
1187 | |
|
|
1188 | my $path = [$wd, undef]; |
|
|
1189 | |
|
|
1190 | for my $name (qw(abc def ghi)) { |
|
|
1191 | $path->[1] = $name; |
|
|
1192 | aio_stat $path, sub { |
|
|
1193 | # ... |
|
|
1194 | }; |
|
|
1195 | } |
|
|
1196 | |
|
|
1197 | There are some caveats: when directories get renamed (or deleted), the |
|
|
1198 | pathname string doesn't change, so will point to the new directory (or |
|
|
1199 | nowhere at all), while the directory fd, if available on the system, |
|
|
1200 | will still point to the original directory. Most functions accepting a |
|
|
1201 | pathname will use the directory fd on newer systems, and the string on |
|
|
1202 | older systems. Some functions (such as "aio_realpath") will always rely |
|
|
1203 | on the string form of the pathname. |
|
|
1204 | |
|
|
1205 | So this functionality is mainly useful to get some protection against |
|
|
1206 | "chdir", to easily get an absolute path out of a relative path for |
|
|
1207 | future reference, and to speed up doing many operations in the same |
|
|
1208 | directory (e.g. when stat'ing all files in a directory). |
|
|
1209 | |
|
|
1210 | The following functions implement this working directory abstraction: |
|
|
1211 | |
|
|
1212 | aio_wd $pathname, $callback->($wd) |
|
|
1213 | Asynchonously canonicalise the given pathname and convert it to an |
|
|
1214 | IO::AIO::WD object representing it. If possible and supported on the |
|
|
1215 | system, also open a directory fd to speed up pathname resolution |
|
|
1216 | relative to this working directory. |
|
|
1217 | |
|
|
1218 | If something goes wrong, then "undef" is passwd to the callback |
|
|
1219 | instead of a working directory object and $! is set appropriately. |
|
|
1220 | Since passing "undef" as working directory component of a pathname |
|
|
1221 | fails the request with "ENOENT", there is often no need for error |
|
|
1222 | checking in the "aio_wd" callback, as future requests using the |
|
|
1223 | value will fail in the expected way. |
|
|
1224 | |
|
|
1225 | IO::AIO::CWD |
|
|
1226 | This is a compiletime constant (object) that represents the process |
|
|
1227 | current working directory. |
|
|
1228 | |
|
|
1229 | Specifying this object as working directory object for a pathname is |
|
|
1230 | as if the pathname would be specified directly, without a directory |
|
|
1231 | object. For example, these calls are functionally identical: |
|
|
1232 | |
|
|
1233 | aio_stat "somefile", sub { ... }; |
|
|
1234 | aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; |
|
|
1235 | |
|
|
1236 | To recover the path associated with an IO::AIO::WD object, you can use |
|
|
1237 | "aio_realpath": |
|
|
1238 | |
|
|
1239 | aio_realpath $wd, sub { |
|
|
1240 | warn "path is $_[0]\n"; |
|
|
1241 | }; |
|
|
1242 | |
|
|
1243 | Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir" |
|
|
1244 | sometimes, fall back to using an absolue path. |
|
|
1245 | |
|
|
1246 | IO::AIO::REQ CLASS |
|
|
1247 | All non-aggregate "aio_*" functions return an object of this class when |
|
|
1248 | called in non-void context. |
|
|
1249 | |
|
|
1250 | cancel $req |
|
|
1251 | Cancels the request, if possible. Has the effect of skipping |
|
|
1252 | execution when entering the execute state and skipping calling the |
|
|
1253 | callback when entering the the result state, but will leave the |
|
|
1254 | request otherwise untouched (with the exception of readdir). That |
|
|
1255 | means that requests that currently execute will not be stopped and |
|
|
1256 | resources held by the request will not be freed prematurely. |
|
|
1257 | |
|
|
1258 | cb $req $callback->(...) |
|
|
1259 | Replace (or simply set) the callback registered to the request. |
|
|
1260 | |
|
|
1261 | IO::AIO::GRP CLASS |
|
|
1262 | This class is a subclass of IO::AIO::REQ, so all its methods apply to |
|
|
1263 | objects of this class, too. |
|
|
1264 | |
|
|
1265 | A IO::AIO::GRP object is a special request that can contain multiple |
|
|
1266 | other aio requests. |
|
|
1267 | |
|
|
1268 | You create one by calling the "aio_group" constructing function with a |
|
|
1269 | callback that will be called when all contained requests have entered |
|
|
1270 | the "done" state: |
|
|
1271 | |
|
|
1272 | my $grp = aio_group sub { |
|
|
1273 | print "all requests are done\n"; |
|
|
1274 | }; |
|
|
1275 | |
|
|
1276 | You add requests by calling the "add" method with one or more |
|
|
1277 | "IO::AIO::REQ" objects: |
|
|
1278 | |
|
|
1279 | $grp->add (aio_unlink "..."); |
|
|
1280 | |
|
|
1281 | add $grp aio_stat "...", sub { |
|
|
1282 | $_[0] or return $grp->result ("error"); |
|
|
1283 | |
|
|
1284 | # add another request dynamically, if first succeeded |
|
|
1285 | add $grp aio_open "...", sub { |
|
|
1286 | $grp->result ("ok"); |
|
|
1287 | }; |
|
|
1288 | }; |
|
|
1289 | |
|
|
1290 | This makes it very easy to create composite requests (see the source of |
|
|
1291 | "aio_move" for an application) that work and feel like simple requests. |
|
|
1292 | |
|
|
1293 | * The IO::AIO::GRP objects will be cleaned up during calls to |
|
|
1294 | "IO::AIO::poll_cb", just like any other request. |
|
|
1295 | |
|
|
1296 | * They can be canceled like any other request. Canceling will cancel |
|
|
1297 | not only the request itself, but also all requests it contains. |
|
|
1298 | |
|
|
1299 | * They can also can also be added to other IO::AIO::GRP objects. |
|
|
1300 | |
|
|
1301 | * You must not add requests to a group from within the group callback |
|
|
1302 | (or any later time). |
|
|
1303 | |
|
|
1304 | Their lifetime, simplified, looks like this: when they are empty, they |
|
|
1305 | will finish very quickly. If they contain only requests that are in the |
|
|
1306 | "done" state, they will also finish. Otherwise they will continue to |
|
|
1307 | exist. |
|
|
1308 | |
|
|
1309 | That means after creating a group you have some time to add requests |
|
|
1310 | (precisely before the callback has been invoked, which is only done |
|
|
1311 | within the "poll_cb"). And in the callbacks of those requests, you can |
|
|
1312 | add further requests to the group. And only when all those requests have |
|
|
1313 | finished will the the group itself finish. |
|
|
1314 | |
|
|
1315 | add $grp ... |
|
|
1316 | $grp->add (...) |
|
|
1317 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
|
|
1318 | be added, including other groups, as long as you do not create |
|
|
1319 | circular dependencies. |
|
|
1320 | |
|
|
1321 | Returns all its arguments. |
|
|
1322 | |
|
|
1323 | $grp->cancel_subs |
|
|
1324 | Cancel all subrequests and clears any feeder, but not the group |
|
|
1325 | request itself. Useful when you queued a lot of events but got a |
|
|
1326 | result early. |
|
|
1327 | |
|
|
1328 | The group request will finish normally (you cannot add requests to |
|
|
1329 | the group). |
|
|
1330 | |
|
|
1331 | $grp->result (...) |
|
|
1332 | Set the result value(s) that will be passed to the group callback |
|
|
1333 | when all subrequests have finished and set the groups errno to the |
|
|
1334 | current value of errno (just like calling "errno" without an error |
|
|
1335 | number). By default, no argument will be passed and errno is zero. |
|
|
1336 | |
|
|
1337 | $grp->errno ([$errno]) |
|
|
1338 | Sets the group errno value to $errno, or the current value of errno |
|
|
1339 | when the argument is missing. |
|
|
1340 | |
|
|
1341 | Every aio request has an associated errno value that is restored |
|
|
1342 | when the callback is invoked. This method lets you change this value |
|
|
1343 | from its default (0). |
|
|
1344 | |
|
|
1345 | Calling "result" will also set errno, so make sure you either set $! |
|
|
1346 | before the call to "result", or call c<errno> after it. |
|
|
1347 | |
|
|
1348 | feed $grp $callback->($grp) |
|
|
1349 | Sets a feeder/generator on this group: every group can have an |
|
|
1350 | attached generator that generates requests if idle. The idea behind |
|
|
1351 | this is that, although you could just queue as many requests as you |
|
|
1352 | want in a group, this might starve other requests for a potentially |
|
|
1353 | long time. For example, "aio_scandir" might generate hundreds of |
|
|
1354 | thousands of "aio_stat" requests, delaying any later requests for a |
|
|
1355 | long time. |
|
|
1356 | |
|
|
1357 | To avoid this, and allow incremental generation of requests, you can |
|
|
1358 | instead a group and set a feeder on it that generates those |
|
|
1359 | requests. The feed callback will be called whenever there are few |
|
|
1360 | enough (see "limit", below) requests active in the group itself and |
|
|
1361 | is expected to queue more requests. |
|
|
1362 | |
|
|
1363 | The feed callback can queue as many requests as it likes (i.e. "add" |
|
|
1364 | does not impose any limits). |
|
|
1365 | |
|
|
1366 | If the feed does not queue more requests when called, it will be |
|
|
1367 | automatically removed from the group. |
|
|
1368 | |
|
|
1369 | If the feed limit is 0 when this method is called, it will be set to |
|
|
1370 | 2 automatically. |
|
|
1371 | |
|
|
1372 | Example: |
|
|
1373 | |
|
|
1374 | # stat all files in @files, but only ever use four aio requests concurrently: |
|
|
1375 | |
|
|
1376 | my $grp = aio_group sub { print "finished\n" }; |
|
|
1377 | limit $grp 4; |
|
|
1378 | feed $grp sub { |
|
|
1379 | my $file = pop @files |
|
|
1380 | or return; |
|
|
1381 | |
|
|
1382 | add $grp aio_stat $file, sub { ... }; |
|
|
1383 | }; |
|
|
1384 | |
|
|
1385 | limit $grp $num |
|
|
1386 | Sets the feeder limit for the group: The feeder will be called |
|
|
1387 | whenever the group contains less than this many requests. |
|
|
1388 | |
|
|
1389 | Setting the limit to 0 will pause the feeding process. |
|
|
1390 | |
|
|
1391 | The default value for the limit is 0, but note that setting a feeder |
|
|
1392 | automatically bumps it up to 2. |
|
|
1393 | |
133 | SUPPORT FUNCTIONS |
1394 | SUPPORT FUNCTIONS |
|
|
1395 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
134 | $fileno = IO::AIO::poll_fileno |
1396 | $fileno = IO::AIO::poll_fileno |
135 | Return the *request result pipe filehandle*. This filehandle must be |
1397 | Return the *request result pipe file descriptor*. This filehandle |
136 | polled for reading by some mechanism outside this module (e.g. Event |
1398 | must be polled for reading by some mechanism outside this module |
137 | or select, see below). If the pipe becomes readable you have to call |
1399 | (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the |
138 | "poll_cb" to check the results. |
1400 | pipe becomes readable you have to call "poll_cb" to check the |
|
|
1401 | results. |
139 | |
1402 | |
140 | See "poll_cb" for an example. |
1403 | See "poll_cb" for an example. |
141 | |
1404 | |
142 | IO::AIO::poll_cb |
1405 | IO::AIO::poll_cb |
143 | Process all outstanding events on the result pipe. You have to call |
1406 | Process some requests that have reached the result phase (i.e. they |
144 | this regularly. Returns the number of events processed. Returns |
1407 | have been executed but the results are not yet reported). You have |
|
|
1408 | to call this "regularly" to finish outstanding requests. |
|
|
1409 | |
|
|
1410 | Returns 0 if all events could be processed (or there were no events |
|
|
1411 | to process), or -1 if it returned earlier for whatever reason. |
145 | immediately when no events are outstanding. |
1412 | Returns immediately when no events are outstanding. The amount of |
|
|
1413 | events processed depends on the settings of "IO::AIO::max_poll_req", |
|
|
1414 | "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding". |
146 | |
1415 | |
147 | You can use Event to multiplex, e.g.: |
1416 | If not all requests were processed for whatever reason, the poll |
|
|
1417 | file descriptor will still be ready when "poll_cb" returns, so |
|
|
1418 | normally you don't have to do anything special to have it called |
|
|
1419 | later. |
|
|
1420 | |
|
|
1421 | Apart from calling "IO::AIO::poll_cb" when the event filehandle |
|
|
1422 | becomes ready, it can be beneficial to call this function from loops |
|
|
1423 | which submit a lot of requests, to make sure the results get |
|
|
1424 | processed when they become available and not just when the loop is |
|
|
1425 | finished and the event loop takes over again. This function returns |
|
|
1426 | very fast when there are no outstanding requests. |
|
|
1427 | |
|
|
1428 | Example: Install an Event watcher that automatically calls |
|
|
1429 | IO::AIO::poll_cb with high priority (more examples can be found in |
|
|
1430 | the SYNOPSIS section, at the top of this document): |
148 | |
1431 | |
149 | Event->io (fd => IO::AIO::poll_fileno, |
1432 | Event->io (fd => IO::AIO::poll_fileno, |
150 | poll => 'r', async => 1, |
1433 | poll => 'r', async => 1, |
151 | cb => \&IO::AIO::poll_cb); |
1434 | cb => \&IO::AIO::poll_cb); |
152 | |
1435 | |
153 | IO::AIO::poll_wait |
1436 | IO::AIO::poll_wait |
154 | Wait till the result filehandle becomes ready for reading (simply |
1437 | Wait until either at least one request is in the result phase or no |
155 | does a select on the filehandle. This is useful if you want to |
1438 | requests are outstanding anymore. |
156 | synchronously wait for some requests to finish). |
1439 | |
|
|
1440 | This is useful if you want to synchronously wait for some requests |
|
|
1441 | to become ready, without actually handling them. |
157 | |
1442 | |
158 | See "nreqs" for an example. |
1443 | See "nreqs" for an example. |
159 | |
1444 | |
|
|
1445 | IO::AIO::poll |
|
|
1446 | Waits until some requests have been handled. |
|
|
1447 | |
|
|
1448 | Returns the number of requests processed, but is otherwise strictly |
|
|
1449 | equivalent to: |
|
|
1450 | |
|
|
1451 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1452 | |
160 | IO::AIO::nreqs |
1453 | IO::AIO::flush |
161 | Returns the number of requests currently outstanding. |
1454 | Wait till all outstanding AIO requests have been handled. |
162 | |
1455 | |
163 | Example: wait till there are no outstanding requests anymore: |
1456 | Strictly equivalent to: |
164 | |
1457 | |
165 | IO::AIO::poll_wait, IO::AIO::poll_cb |
1458 | IO::AIO::poll_wait, IO::AIO::poll_cb |
166 | while IO::AIO::nreqs; |
1459 | while IO::AIO::nreqs; |
167 | |
1460 | |
|
|
1461 | This function can be useful at program aborts, to make sure |
|
|
1462 | outstanding I/O has been done ("IO::AIO" uses an "END" block which |
|
|
1463 | already calls this function on normal exits), or when you are merely |
|
|
1464 | using "IO::AIO" for its more advanced functions, rather than for |
|
|
1465 | async I/O, e.g.: |
|
|
1466 | |
|
|
1467 | my ($dirs, $nondirs); |
|
|
1468 | IO::AIO::aio_scandir "/tmp", 0, sub { ($dirs, $nondirs) = @_ }; |
|
|
1469 | IO::AIO::flush; |
|
|
1470 | # $dirs, $nondirs are now set |
|
|
1471 | |
|
|
1472 | IO::AIO::max_poll_reqs $nreqs |
|
|
1473 | IO::AIO::max_poll_time $seconds |
|
|
1474 | These set the maximum number of requests (default 0, meaning |
|
|
1475 | infinity) that are being processed by "IO::AIO::poll_cb" in one |
|
|
1476 | call, respectively the maximum amount of time (default 0, meaning |
|
|
1477 | infinity) spent in "IO::AIO::poll_cb" to process requests (more |
|
|
1478 | correctly the mininum amount of time "poll_cb" is allowed to use). |
|
|
1479 | |
|
|
1480 | Setting "max_poll_time" to a non-zero value creates an overhead of |
|
|
1481 | one syscall per request processed, which is not normally a problem |
|
|
1482 | unless your callbacks are really really fast or your OS is really |
|
|
1483 | really slow (I am not mentioning Solaris here). Using |
|
|
1484 | "max_poll_reqs" incurs no overhead. |
|
|
1485 | |
|
|
1486 | Setting these is useful if you want to ensure some level of |
|
|
1487 | interactiveness when perl is not fast enough to process all requests |
|
|
1488 | in time. |
|
|
1489 | |
|
|
1490 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
|
|
1491 | |
|
|
1492 | Example: Install an Event watcher that automatically calls |
|
|
1493 | IO::AIO::poll_cb with low priority, to ensure that other parts of |
|
|
1494 | the program get the CPU sometimes even under high AIO load. |
|
|
1495 | |
|
|
1496 | # try not to spend much more than 0.1s in poll_cb |
|
|
1497 | IO::AIO::max_poll_time 0.1; |
|
|
1498 | |
|
|
1499 | # use a low priority so other tasks have priority |
|
|
1500 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1501 | poll => 'r', nice => 1, |
|
|
1502 | cb => &IO::AIO::poll_cb); |
|
|
1503 | |
|
|
1504 | CONTROLLING THE NUMBER OF THREADS |
168 | IO::AIO::min_parallel $nthreads |
1505 | IO::AIO::min_parallel $nthreads |
169 | Set the minimum number of AIO threads to $nthreads. The default is |
1506 | Set the minimum number of AIO threads to $nthreads. The current |
170 | 1, which means a single asynchronous operation can be done at one |
1507 | default is 8, which means eight asynchronous operations can execute |
171 | time (the number of outstanding operations, however, is unlimited). |
1508 | concurrently at any one time (the number of outstanding requests, |
|
|
1509 | however, is unlimited). |
172 | |
1510 | |
|
|
1511 | IO::AIO starts threads only on demand, when an AIO request is queued |
|
|
1512 | and no free thread exists. Please note that queueing up a hundred |
|
|
1513 | requests can create demand for a hundred threads, even if it turns |
|
|
1514 | out that everything is in the cache and could have been processed |
|
|
1515 | faster by a single thread. |
|
|
1516 | |
173 | It is recommended to keep the number of threads low, as some Linux |
1517 | It is recommended to keep the number of threads relatively low, as |
174 | kernel versions will scale negatively with the number of threads |
1518 | some Linux kernel versions will scale negatively with the number of |
175 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
1519 | threads (higher parallelity => MUCH higher latency). With current |
176 | versions, 4-32 threads should be fine. |
1520 | Linux 2.6 versions, 4-32 threads should be fine. |
177 | |
1521 | |
178 | Under normal circumstances you don't need to call this function, as |
1522 | Under most circumstances you don't need to call this function, as |
179 | this module automatically starts some threads (the exact number |
1523 | the module selects a default that is suitable for low to moderate |
180 | might change, and is currently 4). |
1524 | load. |
181 | |
1525 | |
182 | IO::AIO::max_parallel $nthreads |
1526 | IO::AIO::max_parallel $nthreads |
183 | Sets the maximum number of AIO threads to $nthreads. If more than |
1527 | Sets the maximum number of AIO threads to $nthreads. If more than |
184 | the specified number of threads are currently running, kill them. |
1528 | the specified number of threads are currently running, this function |
185 | This function blocks until the limit is reached. |
1529 | kills them. This function blocks until the limit is reached. |
|
|
1530 | |
|
|
1531 | While $nthreads are zero, aio requests get queued but not executed |
|
|
1532 | until the number of threads has been increased again. |
186 | |
1533 | |
187 | This module automatically runs "max_parallel 0" at program end, to |
1534 | This module automatically runs "max_parallel 0" at program end, to |
188 | ensure that all threads are killed and that there are no outstanding |
1535 | ensure that all threads are killed and that there are no outstanding |
189 | requests. |
1536 | requests. |
190 | |
1537 | |
191 | Under normal circumstances you don't need to call this function. |
1538 | Under normal circumstances you don't need to call this function. |
192 | |
1539 | |
|
|
1540 | IO::AIO::max_idle $nthreads |
|
|
1541 | Limit the number of threads (default: 4) that are allowed to idle |
|
|
1542 | (i.e., threads that did not get a request to process within the idle |
|
|
1543 | timeout (default: 10 seconds). That means if a thread becomes idle |
|
|
1544 | while $nthreads other threads are also idle, it will free its |
|
|
1545 | resources and exit. |
|
|
1546 | |
|
|
1547 | This is useful when you allow a large number of threads (e.g. 100 or |
|
|
1548 | 1000) to allow for extremely high load situations, but want to free |
|
|
1549 | resources under normal circumstances (1000 threads can easily |
|
|
1550 | consume 30MB of RAM). |
|
|
1551 | |
|
|
1552 | The default is probably ok in most situations, especially if thread |
|
|
1553 | creation is fast. If thread creation is very slow on your system you |
|
|
1554 | might want to use larger values. |
|
|
1555 | |
|
|
1556 | IO::AIO::idle_timeout $seconds |
|
|
1557 | Sets the minimum idle timeout (default 10) after which worker |
|
|
1558 | threads are allowed to exit. SEe "IO::AIO::max_idle". |
|
|
1559 | |
193 | $oldnreqs = IO::AIO::max_outstanding $nreqs |
1560 | IO::AIO::max_outstanding $maxreqs |
194 | Sets the maximum number of outstanding requests to $nreqs. If you |
1561 | Sets the maximum number of outstanding requests to $nreqs. If you do |
195 | try to queue up more than this number of requests, the caller will |
1562 | queue up more than this number of requests, the next call to |
|
|
1563 | "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as |
|
|
1564 | "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is |
|
|
1565 | no longer exceeded. |
|
|
1566 | |
|
|
1567 | In other words, this setting does not enforce a queue limit, but can |
|
|
1568 | be used to make poll functions block if the limit is exceeded. |
|
|
1569 | |
|
|
1570 | This is a very bad function to use in interactive programs because |
|
|
1571 | it blocks, and a bad way to reduce concurrency because it is |
|
|
1572 | inexact: Better use an "aio_group" together with a feed callback. |
|
|
1573 | |
|
|
1574 | Its main use is in scripts without an event loop - when you want to |
|
|
1575 | stat a lot of files, you can write something like this: |
|
|
1576 | |
|
|
1577 | IO::AIO::max_outstanding 32; |
|
|
1578 | |
|
|
1579 | for my $path (...) { |
|
|
1580 | aio_stat $path , ...; |
|
|
1581 | IO::AIO::poll_cb; |
|
|
1582 | } |
|
|
1583 | |
|
|
1584 | IO::AIO::flush; |
|
|
1585 | |
|
|
1586 | The call to "poll_cb" inside the loop will normally return |
|
|
1587 | instantly, but as soon as more thna 32 reqeusts are in-flight, it |
196 | block until some requests have been handled. |
1588 | will block until some requests have been handled. This keeps the |
|
|
1589 | loop from pushing a large number of "aio_stat" requests onto the |
|
|
1590 | queue. |
197 | |
1591 | |
198 | The default is very large, so normally there is no practical limit. |
1592 | The default value for "max_outstanding" is very large, so there is |
199 | If you queue up many requests in a loop it it often improves speed |
1593 | no practical limit on the number of outstanding requests. |
200 | if you set this to a relatively low number, such as 100. |
|
|
201 | |
1594 | |
202 | Under normal circumstances you don't need to call this function. |
1595 | STATISTICAL INFORMATION |
|
|
1596 | IO::AIO::nreqs |
|
|
1597 | Returns the number of requests currently in the ready, execute or |
|
|
1598 | pending states (i.e. for which their callback has not been invoked |
|
|
1599 | yet). |
|
|
1600 | |
|
|
1601 | Example: wait till there are no outstanding requests anymore: |
|
|
1602 | |
|
|
1603 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1604 | while IO::AIO::nreqs; |
|
|
1605 | |
|
|
1606 | IO::AIO::nready |
|
|
1607 | Returns the number of requests currently in the ready state (not yet |
|
|
1608 | executed). |
|
|
1609 | |
|
|
1610 | IO::AIO::npending |
|
|
1611 | Returns the number of requests currently in the pending state |
|
|
1612 | (executed, but not yet processed by poll_cb). |
|
|
1613 | |
|
|
1614 | SUBSECOND STAT TIME ACCESS |
|
|
1615 | Both "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" functions can |
|
|
1616 | generally find access/modification and change times with subsecond time |
|
|
1617 | accuracy of the system supports it, but perl's built-in functions only |
|
|
1618 | return the integer part. |
|
|
1619 | |
|
|
1620 | The following functions return the timestamps of the most recent stat |
|
|
1621 | with subsecond precision on most systems and work both after |
|
|
1622 | "aio_stat"/"aio_lstat" and perl's "stat"/"lstat" calls. Their return |
|
|
1623 | value is only meaningful after a successful "stat"/"lstat" call, or |
|
|
1624 | during/after a successful "aio_stat"/"aio_lstat" callback. |
|
|
1625 | |
|
|
1626 | This is similar to the Time::HiRes "stat" functions, but can return full |
|
|
1627 | resolution without rounding and work with standard perl "stat", |
|
|
1628 | alleviating the need to call the special "Time::HiRes" functions, which |
|
|
1629 | do not act like their perl counterparts. |
|
|
1630 | |
|
|
1631 | On operating systems or file systems where subsecond time resolution is |
|
|
1632 | not supported or could not be detected, a fractional part of 0 is |
|
|
1633 | returned, so it is always safe to call these functions. |
|
|
1634 | |
|
|
1635 | $seconds = IO::AIO::st_atime, IO::AIO::st_mtime, IO::AIO::st_ctime, |
|
|
1636 | IO::AIO::st_btime |
|
|
1637 | Return the access, modication, change or birth time, respectively, |
|
|
1638 | including fractional part. Due to the limited precision of floating |
|
|
1639 | point, the accuracy on most platforms is only a bit better than |
|
|
1640 | milliseconds for times around now - see the *nsec* function family, |
|
|
1641 | below, for full accuracy. |
|
|
1642 | |
|
|
1643 | File birth time is only available when the OS and perl support it |
|
|
1644 | (on FreeBSD and NetBSD at the time of this writing, although support |
|
|
1645 | is adaptive, so if your OS/perl gains support, IO::AIO can take |
|
|
1646 | avdantage of it). On systems where it isn't available, 0 is |
|
|
1647 | currently returned, but this might change to "undef" in a future |
|
|
1648 | version. |
|
|
1649 | |
|
|
1650 | ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtime |
|
|
1651 | Returns access, modification, change and birth time all in one go, |
|
|
1652 | and maybe more times in the future version. |
|
|
1653 | |
|
|
1654 | $nanoseconds = IO::AIO::st_atimensec, IO::AIO::st_mtimensec, |
|
|
1655 | IO::AIO::st_ctimensec, IO::AIO::st_btimensec |
|
|
1656 | Return the fractional access, modifcation, change or birth time, in |
|
|
1657 | nanoseconds, as an integer in the range 0 to 999999999. |
|
|
1658 | |
|
|
1659 | Note that no accessors are provided for access, modification and |
|
|
1660 | change times - you need to get those from "stat _" if required ("int |
|
|
1661 | IO::AIO::st_atime" and so on will *not* generally give you the |
|
|
1662 | correct value). |
|
|
1663 | |
|
|
1664 | $seconds = IO::AIO::st_btimesec |
|
|
1665 | The (integral) seconds part of the file birth time, if available. |
|
|
1666 | |
|
|
1667 | ($atime, $mtime, $ctime, $btime, ...) = IO::AIO::st_xtimensec |
|
|
1668 | Like the functions above, but returns all four times in one go (and |
|
|
1669 | maybe more in future versions). |
|
|
1670 | |
|
|
1671 | $counter = IO::AIO::st_gen |
|
|
1672 | Returns the generation counter (in practice this is just a random |
|
|
1673 | number) of the file. This is only available on platforms which have |
|
|
1674 | this member in their "struct stat" (most BSDs at the time of this |
|
|
1675 | writing) and generally only to the root usert. If unsupported, 0 is |
|
|
1676 | returned, but this might change to "undef" in a future version. |
|
|
1677 | |
|
|
1678 | Example: print the high resolution modification time of /etc, using |
|
|
1679 | "stat", and "IO::AIO::aio_stat". |
|
|
1680 | |
|
|
1681 | if (stat "/etc") { |
|
|
1682 | printf "stat(/etc) mtime: %f\n", IO::AIO::st_mtime; |
|
|
1683 | } |
|
|
1684 | |
|
|
1685 | IO::AIO::aio_stat "/etc", sub { |
|
|
1686 | $_[0] |
|
|
1687 | and return; |
|
|
1688 | |
|
|
1689 | printf "aio_stat(/etc) mtime: %d.%09d\n", (stat _)[9], IO::AIO::st_mtimensec; |
|
|
1690 | }; |
|
|
1691 | |
|
|
1692 | IO::AIO::flush; |
|
|
1693 | |
|
|
1694 | Output of the awbove on my system, showing reduced and full accuracy: |
|
|
1695 | |
|
|
1696 | stat(/etc) mtime: 1534043702.020808 |
|
|
1697 | aio_stat(/etc) mtime: 1534043702.020807792 |
|
|
1698 | |
|
|
1699 | MISCELLANEOUS FUNCTIONS |
|
|
1700 | IO::AIO implements some functions that are useful when you want to use |
|
|
1701 | some "Advanced I/O" function not available to in Perl, without going the |
|
|
1702 | "Asynchronous I/O" route. Many of these have an asynchronous "aio_*" |
|
|
1703 | counterpart. |
|
|
1704 | |
|
|
1705 | $numfd = IO::AIO::get_fdlimit |
|
|
1706 | This function is *EXPERIMENTAL* and subject to change. |
|
|
1707 | |
|
|
1708 | Tries to find the current file descriptor limit and returns it, or |
|
|
1709 | "undef" and sets $! in case of an error. The limit is one larger |
|
|
1710 | than the highest valid file descriptor number. |
|
|
1711 | |
|
|
1712 | IO::AIO::min_fdlimit [$numfd] |
|
|
1713 | This function is *EXPERIMENTAL* and subject to change. |
|
|
1714 | |
|
|
1715 | Try to increase the current file descriptor limit(s) to at least |
|
|
1716 | $numfd by changing the soft or hard file descriptor resource limit. |
|
|
1717 | If $numfd is missing, it will try to set a very high limit, although |
|
|
1718 | this is not recommended when you know the actual minimum that you |
|
|
1719 | require. |
|
|
1720 | |
|
|
1721 | If the limit cannot be raised enough, the function makes a |
|
|
1722 | best-effort attempt to increase the limit as much as possible, using |
|
|
1723 | various tricks, while still failing. You can query the resulting |
|
|
1724 | limit using "IO::AIO::get_fdlimit". |
|
|
1725 | |
|
|
1726 | If an error occurs, returns "undef" and sets $!, otherwise returns |
|
|
1727 | true. |
|
|
1728 | |
|
|
1729 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
|
|
1730 | Calls the "eio_sendfile_sync" function, which is like |
|
|
1731 | "aio_sendfile", but is blocking (this makes most sense if you know |
|
|
1732 | the input data is likely cached already and the output filehandle is |
|
|
1733 | set to non-blocking operations). |
|
|
1734 | |
|
|
1735 | Returns the number of bytes copied, or -1 on error. |
|
|
1736 | |
|
|
1737 | IO::AIO::fadvise $fh, $offset, $len, $advice |
|
|
1738 | Simply calls the "posix_fadvise" function (see its manpage for |
|
|
1739 | details). The following advice constants are available: |
|
|
1740 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
|
|
1741 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
|
|
1742 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
|
|
1743 | |
|
|
1744 | On systems that do not implement "posix_fadvise", this function |
|
|
1745 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
|
|
1746 | |
|
|
1747 | IO::AIO::madvise $scalar, $offset, $len, $advice |
|
|
1748 | Simply calls the "posix_madvise" function (see its manpage for |
|
|
1749 | details). The following advice constants are available: |
|
|
1750 | "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", |
|
|
1751 | "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", |
|
|
1752 | "IO::AIO::MADV_DONTNEED". |
|
|
1753 | |
|
|
1754 | If $offset is negative, counts from the end. If $length is negative, |
|
|
1755 | the remaining length of the $scalar is used. If possible, $length |
|
|
1756 | will be reduced to fit into the $scalar. |
|
|
1757 | |
|
|
1758 | On systems that do not implement "posix_madvise", this function |
|
|
1759 | returns ENOSYS, otherwise the return value of "posix_madvise". |
|
|
1760 | |
|
|
1761 | IO::AIO::mprotect $scalar, $offset, $len, $protect |
|
|
1762 | Simply calls the "mprotect" function on the preferably AIO::mmap'ed |
|
|
1763 | $scalar (see its manpage for details). The following protect |
|
|
1764 | constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", |
|
|
1765 | "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". |
|
|
1766 | |
|
|
1767 | If $offset is negative, counts from the end. If $length is negative, |
|
|
1768 | the remaining length of the $scalar is used. If possible, $length |
|
|
1769 | will be reduced to fit into the $scalar. |
|
|
1770 | |
|
|
1771 | On systems that do not implement "mprotect", this function returns |
|
|
1772 | ENOSYS, otherwise the return value of "mprotect". |
|
|
1773 | |
|
|
1774 | IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
|
|
1775 | Memory-maps a file (or anonymous memory range) and attaches it to |
|
|
1776 | the given $scalar, which will act like a string scalar. Returns true |
|
|
1777 | on success, and false otherwise. |
|
|
1778 | |
|
|
1779 | The scalar must exist, but its contents do not matter - this means |
|
|
1780 | you cannot use a nonexistant array or hash element. When in doubt, |
|
|
1781 | "undef" the scalar first. |
|
|
1782 | |
|
|
1783 | The only operations allowed on the mmapped scalar are |
|
|
1784 | "substr"/"vec", which don't change the string length, and most |
|
|
1785 | read-only operations such as copying it or searching it with regexes |
|
|
1786 | and so on. |
|
|
1787 | |
|
|
1788 | Anything else is unsafe and will, at best, result in memory leaks. |
|
|
1789 | |
|
|
1790 | The memory map associated with the $scalar is automatically removed |
|
|
1791 | when the $scalar is undef'd or destroyed, or when the |
|
|
1792 | "IO::AIO::mmap" or "IO::AIO::munmap" functions are called on it. |
|
|
1793 | |
|
|
1794 | This calls the "mmap"(2) function internally. See your system's |
|
|
1795 | manual page for details on the $length, $prot and $flags parameters. |
|
|
1796 | |
|
|
1797 | The $length must be larger than zero and smaller than the actual |
|
|
1798 | filesize. |
|
|
1799 | |
|
|
1800 | $prot is a combination of "IO::AIO::PROT_NONE", |
|
|
1801 | "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or |
|
|
1802 | "IO::AIO::PROT_WRITE", |
|
|
1803 | |
|
|
1804 | $flags can be a combination of "IO::AIO::MAP_SHARED" or |
|
|
1805 | "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when |
|
|
1806 | not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to |
|
|
1807 | "MAP_ANON" if your system only provides this constant), |
|
|
1808 | "IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE", |
|
|
1809 | "IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK", |
|
|
1810 | "IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN", |
|
|
1811 | "IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or |
|
|
1812 | "IO::AIO::MAP_STACK". |
|
|
1813 | |
|
|
1814 | If $fh is "undef", then a file descriptor of -1 is passed. |
|
|
1815 | |
|
|
1816 | $offset is the offset from the start of the file - it generally must |
|
|
1817 | be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. |
|
|
1818 | |
|
|
1819 | Example: |
|
|
1820 | |
|
|
1821 | use Digest::MD5; |
|
|
1822 | use IO::AIO; |
|
|
1823 | |
|
|
1824 | open my $fh, "<verybigfile" |
|
|
1825 | or die "$!"; |
|
|
1826 | |
|
|
1827 | IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh |
|
|
1828 | or die "verybigfile: $!"; |
|
|
1829 | |
|
|
1830 | my $fast_md5 = md5 $data; |
|
|
1831 | |
|
|
1832 | IO::AIO::munmap $scalar |
|
|
1833 | Removes a previous mmap and undefines the $scalar. |
|
|
1834 | |
|
|
1835 | IO::AIO::mremap $scalar, $new_length, $flags = MREMAP_MAYMOVE[, |
|
|
1836 | $new_address = 0] |
|
|
1837 | Calls the Linux-specific mremap(2) system call. The $scalar must |
|
|
1838 | have been mapped by "IO::AIO::mmap", and $flags must currently |
|
|
1839 | either be 0 or "IO::AIO::MREMAP_MAYMOVE". |
|
|
1840 | |
|
|
1841 | Returns true if successful, and false otherwise. If the underlying |
|
|
1842 | mmapped region has changed address, then the true value has the |
|
|
1843 | numerical value 1, otherwise it has the numerical value 0: |
|
|
1844 | |
|
|
1845 | my $success = IO::AIO::mremap $mmapped, 8192, IO::AIO::MREMAP_MAYMOVE |
|
|
1846 | or die "mremap: $!"; |
|
|
1847 | |
|
|
1848 | if ($success*1) { |
|
|
1849 | warn "scalar has chanegd address in memory\n"; |
|
|
1850 | } |
|
|
1851 | |
|
|
1852 | "IO::AIO::MREMAP_FIXED" and the $new_address argument are currently |
|
|
1853 | implemented, but not supported and might go away in a future |
|
|
1854 | version. |
|
|
1855 | |
|
|
1856 | On systems where this call is not supported or is not emulated, this |
|
|
1857 | call returns falls and sets $! to "ENOSYS". |
|
|
1858 | |
|
|
1859 | IO::AIO::mlockall $flags |
|
|
1860 | Calls the "eio_mlockall_sync" function, which is like |
|
|
1861 | "aio_mlockall", but is blocking. |
|
|
1862 | |
|
|
1863 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
|
|
1864 | Calls the "munlock" function, undoing the effects of a previous |
|
|
1865 | "aio_mlock" call (see its description for details). |
|
|
1866 | |
|
|
1867 | IO::AIO::munlockall |
|
|
1868 | Calls the "munlockall" function. |
|
|
1869 | |
|
|
1870 | On systems that do not implement "munlockall", this function returns |
|
|
1871 | ENOSYS, otherwise the return value of "munlockall". |
|
|
1872 | |
|
|
1873 | IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags |
|
|
1874 | Calls the GNU/Linux splice(2) syscall, if available. If $r_off or |
|
|
1875 | $w_off are "undef", then "NULL" is passed for these, otherwise they |
|
|
1876 | should be the file offset. |
|
|
1877 | |
|
|
1878 | $r_fh and $w_fh should not refer to the same file, as splice might |
|
|
1879 | silently corrupt the data in this case. |
|
|
1880 | |
|
|
1881 | The following symbol flag values are available: |
|
|
1882 | "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK", |
|
|
1883 | "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT". |
|
|
1884 | |
|
|
1885 | See the splice(2) manpage for details. |
|
|
1886 | |
|
|
1887 | IO::AIO::tee $r_fh, $w_fh, $length, $flags |
|
|
1888 | Calls the GNU/Linux tee(2) syscall, see its manpage and the |
|
|
1889 | description for "IO::AIO::splice" above for details. |
|
|
1890 | |
|
|
1891 | $actual_size = IO::AIO::pipesize $r_fh[, $new_size] |
|
|
1892 | Attempts to query or change the pipe buffer size. Obviously works |
|
|
1893 | only on pipes, and currently works only on GNU/Linux systems, and |
|
|
1894 | fails with -1/"ENOSYS" everywhere else. If anybody knows how to |
|
|
1895 | influence pipe buffer size on other systems, drop me a note. |
|
|
1896 | |
|
|
1897 | ($rfh, $wfh) = IO::AIO::pipe2 [$flags] |
|
|
1898 | This is a direct interface to the Linux pipe2(2) system call. If |
|
|
1899 | $flags is missing or 0, then this should be the same as a call to |
|
|
1900 | perl's built-in "pipe" function and create a new pipe, and works on |
|
|
1901 | systems that lack the pipe2 syscall. On win32, this case invokes |
|
|
1902 | "_pipe (..., 4096, O_BINARY)". |
|
|
1903 | |
|
|
1904 | If $flags is non-zero, it tries to invoke the pipe2 system call with |
|
|
1905 | the given flags (Linux 2.6.27, glibc 2.9). |
|
|
1906 | |
|
|
1907 | On success, the read and write file handles are returned. |
|
|
1908 | |
|
|
1909 | On error, nothing will be returned. If the pipe2 syscall is missing |
|
|
1910 | and $flags is non-zero, fails with "ENOSYS". |
|
|
1911 | |
|
|
1912 | Please refer to pipe2(2) for more info on the $flags, but at the |
|
|
1913 | time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK" |
|
|
1914 | and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were |
|
|
1915 | supported. |
|
|
1916 | |
|
|
1917 | Example: create a pipe race-free w.r.t. threads and fork: |
|
|
1918 | |
|
|
1919 | my ($rfh, $wfh) = IO::AIO::pipe2 IO::AIO::O_CLOEXEC |
|
|
1920 | or die "pipe2: $!\n"; |
|
|
1921 | |
|
|
1922 | $fh = IO::AIO::eventfd [$initval, [$flags]] |
|
|
1923 | This is a direct interface to the Linux eventfd(2) system call. The |
|
|
1924 | (unhelpful) defaults for $initval and $flags are 0 for both. |
|
|
1925 | |
|
|
1926 | On success, the new eventfd filehandle is returned, otherwise |
|
|
1927 | returns "undef". If the eventfd syscall is missing, fails with |
|
|
1928 | "ENOSYS". |
|
|
1929 | |
|
|
1930 | Please refer to eventfd(2) for more info on this call. |
|
|
1931 | |
|
|
1932 | The following symbol flag values are available: |
|
|
1933 | "IO::AIO::EFD_CLOEXEC", "IO::AIO::EFD_NONBLOCK" and |
|
|
1934 | "IO::AIO::EFD_SEMAPHORE" (Linux 2.6.30). |
|
|
1935 | |
|
|
1936 | Example: create a new eventfd filehandle: |
|
|
1937 | |
|
|
1938 | $fh = IO::AIO::eventfd 0, IO::AIO::O_CLOEXEC |
|
|
1939 | or die "eventfd: $!\n"; |
|
|
1940 | |
|
|
1941 | $fh = IO::AIO::timerfd_create $clockid[, $flags] |
|
|
1942 | This is a direct interface to the Linux timerfd_create(2) system |
|
|
1943 | call. The (unhelpful) default for $flags is 0. |
|
|
1944 | |
|
|
1945 | On success, the new timerfd filehandle is returned, otherwise |
|
|
1946 | returns "undef". If the eventfd syscall is missing, fails with |
|
|
1947 | "ENOSYS". |
|
|
1948 | |
|
|
1949 | Please refer to timerfd_create(2) for more info on this call. |
|
|
1950 | |
|
|
1951 | The following $clockid values are available: |
|
|
1952 | "IO::AIO::CLOCK_REALTIME", "IO::AIO::CLOCK_MONOTONIC" |
|
|
1953 | "IO::AIO::CLOCK_CLOCK_BOOTTIME" (Linux 3.15) |
|
|
1954 | "IO::AIO::CLOCK_CLOCK_REALTIME_ALARM" (Linux 3.11) and |
|
|
1955 | "IO::AIO::CLOCK_CLOCK_BOOTTIME_ALARM" (Linux 3.11). |
|
|
1956 | |
|
|
1957 | The following $flags values are available (Linux 2.6.27): |
|
|
1958 | "IO::AIO::TFD_NONBLOCK" and "IO::AIO::TFD_CLOEXEC". |
|
|
1959 | |
|
|
1960 | Example: create a new timerfd and set it to one-second repeated |
|
|
1961 | alarms, then wait for two alarms: |
|
|
1962 | |
|
|
1963 | my $fh = IO::AIO::timerfd_create IO::AIO::CLOCK_BOOTTIME, IO::AIO::TFD_CLOEXEC |
|
|
1964 | or die "timerfd_create: $!\n"; |
|
|
1965 | |
|
|
1966 | defined IO::AIO::timerfd_settime $fh, 0, 1, 1 |
|
|
1967 | or die "timerfd_settime: $!\n"; |
|
|
1968 | |
|
|
1969 | for (1..2) { |
|
|
1970 | 8 == sysread $fh, my $buf, 8 |
|
|
1971 | or die "timerfd read failure\n"; |
|
|
1972 | |
|
|
1973 | printf "number of expirations (likely 1): %d\n", |
|
|
1974 | unpack "Q", $buf; |
|
|
1975 | } |
|
|
1976 | |
|
|
1977 | ($cur_interval, $cur_value) = IO::AIO::timerfd_settime $fh, $flags, |
|
|
1978 | $new_interval, $nbw_value |
|
|
1979 | This is a direct interface to the Linux timerfd_settime(2) system |
|
|
1980 | call. Please refer to its manpage for more info on this call. |
|
|
1981 | |
|
|
1982 | The new itimerspec is specified using two (possibly fractional) |
|
|
1983 | second values, $new_interval and $new_value). |
|
|
1984 | |
|
|
1985 | On success, the current interval and value are returned (as per |
|
|
1986 | "timerfd_gettime"). On failure, the empty list is returned. |
|
|
1987 | |
|
|
1988 | The following $flags values are available: |
|
|
1989 | "IO::AIO::TFD_TIMER_ABSTIME" and "IO::AIO::TFD_TIMER_CANCEL_ON_SET". |
|
|
1990 | |
|
|
1991 | See "IO::AIO::timerfd_create" for a full example. |
|
|
1992 | |
|
|
1993 | ($cur_interval, $cur_value) = IO::AIO::timerfd_gettime $fh |
|
|
1994 | This is a direct interface to the Linux timerfd_gettime(2) system |
|
|
1995 | call. Please refer to its manpage for more info on this call. |
|
|
1996 | |
|
|
1997 | On success, returns the current values of interval and value for the |
|
|
1998 | given timerfd (as potentially fractional second values). On failure, |
|
|
1999 | the empty list is returned. |
|
|
2000 | |
|
|
2001 | EVENT LOOP INTEGRATION |
|
|
2002 | It is recommended to use AnyEvent::AIO to integrate IO::AIO |
|
|
2003 | automatically into many event loops: |
|
|
2004 | |
|
|
2005 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
|
|
2006 | use AnyEvent::AIO; |
|
|
2007 | |
|
|
2008 | You can also integrate IO::AIO manually into many event loops, here are |
|
|
2009 | some examples of how to do this: |
|
|
2010 | |
|
|
2011 | # EV integration |
|
|
2012 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
|
|
2013 | |
|
|
2014 | # Event integration |
|
|
2015 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
2016 | poll => 'r', |
|
|
2017 | cb => \&IO::AIO::poll_cb); |
|
|
2018 | |
|
|
2019 | # Glib/Gtk2 integration |
|
|
2020 | add_watch Glib::IO IO::AIO::poll_fileno, |
|
|
2021 | in => sub { IO::AIO::poll_cb; 1 }; |
|
|
2022 | |
|
|
2023 | # Tk integration |
|
|
2024 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
|
|
2025 | readable => \&IO::AIO::poll_cb); |
|
|
2026 | |
|
|
2027 | # Danga::Socket integration |
|
|
2028 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
|
|
2029 | \&IO::AIO::poll_cb); |
|
|
2030 | |
|
|
2031 | FORK BEHAVIOUR |
|
|
2032 | Usage of pthreads in a program changes the semantics of fork |
|
|
2033 | considerably. Specifically, only async-safe functions can be called |
|
|
2034 | after fork. Perl doesn't know about this, so in general, you cannot call |
|
|
2035 | fork with defined behaviour in perl if pthreads are involved. IO::AIO |
|
|
2036 | uses pthreads, so this applies, but many other extensions and (for |
|
|
2037 | inexplicable reasons) perl itself often is linked against pthreads, so |
|
|
2038 | this limitation applies to quite a lot of perls. |
|
|
2039 | |
|
|
2040 | This module no longer tries to fight your OS, or POSIX. That means |
|
|
2041 | IO::AIO only works in the process that loaded it. Forking is fully |
|
|
2042 | supported, but using IO::AIO in the child is not. |
|
|
2043 | |
|
|
2044 | You might get around by not *using* IO::AIO before (or after) forking. |
|
|
2045 | You could also try to call the IO::AIO::reinit function in the child: |
|
|
2046 | |
|
|
2047 | IO::AIO::reinit |
|
|
2048 | Abandons all current requests and I/O threads and simply |
|
|
2049 | reinitialises all data structures. This is not an operation |
|
|
2050 | supported by any standards, but happens to work on GNU/Linux and |
|
|
2051 | some newer BSD systems. |
|
|
2052 | |
|
|
2053 | The only reasonable use for this function is to call it after |
|
|
2054 | forking, if "IO::AIO" was used in the parent. Calling it while |
|
|
2055 | IO::AIO is active in the process will result in undefined behaviour. |
|
|
2056 | Calling it at any time will also result in any undefined (by POSIX) |
|
|
2057 | behaviour. |
|
|
2058 | |
|
|
2059 | LINUX-SPECIFIC CALLS |
|
|
2060 | When a call is documented as "linux-specific" then this means it |
|
|
2061 | originated on GNU/Linux. "IO::AIO" will usually try to autodetect the |
|
|
2062 | availability and compatibility of such calls regardless of the platform |
|
|
2063 | it is compiled on, so platforms such as FreeBSD which often implement |
|
|
2064 | these calls will work. When in doubt, call them and see if they fail wth |
|
|
2065 | "ENOSYS". |
|
|
2066 | |
|
|
2067 | MEMORY USAGE |
|
|
2068 | Per-request usage: |
|
|
2069 | |
|
|
2070 | Each aio request uses - depending on your architecture - around 100-200 |
|
|
2071 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
|
|
2072 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
|
|
2073 | scalars and other data passed into aio requests will also be locked and |
|
|
2074 | will consume memory till the request has entered the done state. |
|
|
2075 | |
|
|
2076 | This is not awfully much, so queuing lots of requests is not usually a |
|
|
2077 | problem. |
|
|
2078 | |
|
|
2079 | Per-thread usage: |
|
|
2080 | |
|
|
2081 | In the execution phase, some aio requests require more memory for |
|
|
2082 | temporary buffers, and each thread requires a stack and other data |
|
|
2083 | structures (usually around 16k-128k, depending on the OS). |
|
|
2084 | |
|
|
2085 | KNOWN BUGS |
|
|
2086 | Known bugs will be fixed in the next release :) |
|
|
2087 | |
|
|
2088 | KNOWN ISSUES |
|
|
2089 | Calls that try to "import" foreign memory areas (such as "IO::AIO::mmap" |
|
|
2090 | or "IO::AIO::aio_slurp") do not work with generic lvalues, such as |
|
|
2091 | non-created hash slots or other scalars I didn't think of. It's best to |
|
|
2092 | avoid such and either use scalar variables or making sure that the |
|
|
2093 | scalar exists (e.g. by storing "undef") and isn't "funny" (e.g. tied). |
|
|
2094 | |
|
|
2095 | I am not sure anything can be done about this, so this is considered a |
|
|
2096 | known issue, rather than a bug. |
203 | |
2097 | |
204 | SEE ALSO |
2098 | SEE ALSO |
205 | Coro, Linux::AIO. |
2099 | AnyEvent::AIO for easy integration into event loops, Coro::AIO for a |
|
|
2100 | more natural syntax. |
206 | |
2101 | |
207 | AUTHOR |
2102 | AUTHOR |
208 | Marc Lehmann <schmorp@schmorp.de> |
2103 | Marc Lehmann <schmorp@schmorp.de> |
209 | http://home.schmorp.de/ |
2104 | http://home.schmorp.de/ |
210 | |
2105 | |