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2 | IO::AIO - Asynchronous Input/Output |
2 | IO::AIO - Asynchronous Input/Output |
3 | |
3 | |
4 | SYNOPSIS |
4 | SYNOPSIS |
5 | use IO::AIO; |
5 | use IO::AIO; |
6 | |
6 | |
7 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
7 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
8 | my ($fh) = @_; |
8 | my $fh = shift |
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9 | or die "/etc/passwd: $!"; |
9 | ... |
10 | ... |
10 | }; |
11 | }; |
11 | |
12 | |
12 | aio_unlink "/tmp/file", sub { }; |
13 | aio_unlink "/tmp/file", sub { }; |
13 | |
14 | |
14 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
15 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
15 | $_[0] > 0 or die "read error: $!"; |
16 | $_[0] > 0 or die "read error: $!"; |
16 | }; |
17 | }; |
17 | |
18 | |
18 | # Event |
19 | # version 2+ has request and group objects |
19 | Event->io (fd => IO::AIO::poll_fileno, |
20 | use IO::AIO 2; |
20 | poll => 'r', |
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21 | cb => \&IO::AIO::poll_cb); |
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22 | |
21 | |
23 | # Glib/Gtk2 |
22 | aioreq_pri 4; # give next request a very high priority |
24 | add_watch Glib::IO IO::AIO::poll_fileno, |
23 | my $req = aio_unlink "/tmp/file", sub { }; |
25 | \&IO::AIO::poll_cb; |
24 | $req->cancel; # cancel request if still in queue |
26 | |
25 | |
27 | # Tk |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
28 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
27 | add $grp aio_stat "..." for ...; |
29 | readable => \&IO::AIO::poll_cb); |
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30 | |
28 | |
31 | DESCRIPTION |
29 | DESCRIPTION |
32 | This module implements asynchronous I/O using whatever means your |
30 | This module implements asynchronous I/O using whatever means your |
33 | 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>). |
34 | |
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 | |
35 | 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 |
36 | 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 |
37 | 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 |
38 | 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 |
39 | native aio functions available on many operating systems. However, they |
54 | functions available on many operating systems. However, they are often |
40 | 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 |
41 | currently, for example), and they would only support aio_read and |
56 | files currently, for example), and they would only support aio_read and |
42 | aio_write, so the remaining functionality would have to be implemented |
57 | aio_write, so the remaining functionality would have to be implemented |
43 | using threads anyway. |
58 | using threads anyway. |
44 | |
59 | |
45 | Although the module will work with in the presence of other threads, it |
60 | Although the module will work in the presence of other (Perl-) threads, |
46 | is currently not reentrant, so use appropriate locking yourself. |
61 | it is currently not reentrant in any way, so use appropriate locking |
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62 | yourself, always call "poll_cb" from within the same thread, or never |
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63 | call "poll_cb" (or other "aio_" functions) recursively. |
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64 | |
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65 | EXAMPLE |
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66 | This is a simple example that uses the EV module and loads /etc/passwd |
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67 | asynchronously: |
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68 | |
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69 | use EV; |
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70 | use IO::AIO; |
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71 | |
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72 | # register the IO::AIO callback with EV |
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73 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
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74 | |
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75 | # queue the request to open /etc/passwd |
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76 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
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77 | my $fh = shift |
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78 | or die "error while opening: $!"; |
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79 | |
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80 | # stat'ing filehandles is generally non-blocking |
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81 | my $size = -s $fh; |
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82 | |
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83 | # queue a request to read the file |
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84 | my $contents; |
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85 | aio_read $fh, 0, $size, $contents, 0, sub { |
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86 | $_[0] == $size |
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87 | or die "short read: $!"; |
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88 | |
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89 | close $fh; |
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90 | |
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91 | # file contents now in $contents |
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92 | print $contents; |
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93 | |
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94 | # exit event loop and program |
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95 | EV::unloop; |
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96 | }; |
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97 | }; |
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98 | |
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99 | # possibly queue up other requests, or open GUI windows, |
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100 | # check for sockets etc. etc. |
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101 | |
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102 | # process events as long as there are some: |
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103 | EV::loop; |
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104 | |
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105 | REQUEST ANATOMY AND LIFETIME |
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106 | Every "aio_*" function creates a request. which is a C data structure |
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107 | not directly visible to Perl. |
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108 | |
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109 | If called in non-void context, every request function returns a Perl |
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110 | object representing the request. In void context, nothing is returned, |
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111 | which saves a bit of memory. |
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112 | |
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113 | The perl object is a fairly standard ref-to-hash object. The hash |
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114 | contents are not used by IO::AIO so you are free to store anything you |
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115 | like in it. |
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116 | |
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117 | During their existance, aio requests travel through the following |
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118 | states, in order: |
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119 | |
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120 | ready |
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121 | Immediately after a request is created it is put into the ready |
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122 | state, waiting for a thread to execute it. |
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123 | |
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124 | execute |
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125 | A thread has accepted the request for processing and is currently |
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126 | executing it (e.g. blocking in read). |
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127 | |
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128 | pending |
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129 | The request has been executed and is waiting for result processing. |
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130 | |
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131 | While request submission and execution is fully asynchronous, result |
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132 | processing is not and relies on the perl interpreter calling |
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133 | "poll_cb" (or another function with the same effect). |
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134 | |
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135 | result |
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136 | The request results are processed synchronously by "poll_cb". |
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137 | |
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138 | The "poll_cb" function will process all outstanding aio requests by |
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139 | calling their callbacks, freeing memory associated with them and |
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140 | managing any groups they are contained in. |
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141 | |
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142 | done |
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143 | Request has reached the end of its lifetime and holds no resources |
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144 | anymore (except possibly for the Perl object, but its connection to |
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145 | the actual aio request is severed and calling its methods will |
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146 | either do nothing or result in a runtime error). |
47 | |
147 | |
48 | FUNCTIONS |
148 | FUNCTIONS |
49 | AIO FUNCTIONS |
149 | QUICK OVERVIEW |
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150 | This section simply lists the prototypes most of the functions for quick |
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151 | reference. See the following sections for function-by-function |
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152 | documentation. |
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153 | |
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154 | aio_wd $pathname, $callback->($wd) |
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155 | aio_open $pathname, $flags, $mode, $callback->($fh) |
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156 | aio_close $fh, $callback->($status) |
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157 | aio_seek $fh,$offset,$whence, $callback->($offs) |
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158 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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159 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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160 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
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161 | aio_readahead $fh,$offset,$length, $callback->($retval) |
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162 | aio_stat $fh_or_path, $callback->($status) |
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163 | aio_lstat $fh, $callback->($status) |
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164 | aio_statvfs $fh_or_path, $callback->($statvfs) |
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165 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
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166 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
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167 | aio_chmod $fh_or_path, $mode, $callback->($status) |
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168 | aio_truncate $fh_or_path, $offset, $callback->($status) |
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169 | aio_allocate $fh, $mode, $offset, $len, $callback->($status) |
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170 | aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) |
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171 | aio_unlink $pathname, $callback->($status) |
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172 | aio_mknod $pathname, $mode, $dev, $callback->($status) |
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173 | aio_link $srcpath, $dstpath, $callback->($status) |
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174 | aio_symlink $srcpath, $dstpath, $callback->($status) |
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175 | aio_readlink $pathname, $callback->($link) |
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176 | aio_realpath $pathname, $callback->($link) |
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177 | aio_rename $srcpath, $dstpath, $callback->($status) |
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178 | aio_mkdir $pathname, $mode, $callback->($status) |
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179 | aio_rmdir $pathname, $callback->($status) |
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180 | aio_readdir $pathname, $callback->($entries) |
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181 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
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182 | IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST |
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183 | IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN |
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184 | aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) |
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185 | aio_load $pathname, $data, $callback->($status) |
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186 | aio_copy $srcpath, $dstpath, $callback->($status) |
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187 | aio_move $srcpath, $dstpath, $callback->($status) |
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188 | aio_rmtree $pathname, $callback->($status) |
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189 | aio_sync $callback->($status) |
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190 | aio_syncfs $fh, $callback->($status) |
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191 | aio_fsync $fh, $callback->($status) |
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192 | aio_fdatasync $fh, $callback->($status) |
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193 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
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194 | aio_pathsync $pathname, $callback->($status) |
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195 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
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196 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
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197 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
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198 | aio_mlockall $flags, $callback->($status) |
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199 | aio_group $callback->(...) |
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200 | aio_nop $callback->() |
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201 | |
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202 | $prev_pri = aioreq_pri [$pri] |
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203 | aioreq_nice $pri_adjust |
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204 | |
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205 | IO::AIO::poll_wait |
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206 | IO::AIO::poll_cb |
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207 | IO::AIO::poll |
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208 | IO::AIO::flush |
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209 | IO::AIO::max_poll_reqs $nreqs |
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210 | IO::AIO::max_poll_time $seconds |
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211 | IO::AIO::min_parallel $nthreads |
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212 | IO::AIO::max_parallel $nthreads |
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213 | IO::AIO::max_idle $nthreads |
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214 | IO::AIO::idle_timeout $seconds |
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215 | IO::AIO::max_outstanding $maxreqs |
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216 | IO::AIO::nreqs |
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217 | IO::AIO::nready |
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218 | IO::AIO::npending |
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219 | |
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220 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
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221 | IO::AIO::fadvise $fh, $offset, $len, $advice |
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222 | IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]] |
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223 | IO::AIO::munmap $scalar |
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224 | IO::AIO::madvise $scalar, $offset, $length, $advice |
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225 | IO::AIO::mprotect $scalar, $offset, $length, $protect |
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226 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
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227 | IO::AIO::munlockall |
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228 | |
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229 | API NOTES |
50 | All the "aio_*" calls are more or less thin wrappers around the syscall |
230 | All the "aio_*" calls are more or less thin wrappers around the syscall |
51 | with the same name (sans "aio_"). The arguments are similar or |
231 | with the same name (sans "aio_"). The arguments are similar or |
52 | identical, and they all accept an additional $callback argument which |
232 | identical, and they all accept an additional (and optional) $callback |
53 | must be a code reference. This code reference will get called with the |
233 | argument which must be a code reference. This code reference will be |
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234 | called after the syscall has been executed in an asynchronous fashion. |
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235 | The results of the request will be passed as arguments to the callback |
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236 | (and, if an error occured, in $!) - for most requests the syscall return |
54 | syscall return code (e.g. most syscalls return -1 on error, unlike perl, |
237 | code (e.g. most syscalls return -1 on error, unlike perl, which usually |
55 | which usually delivers "false") as it's sole argument when the given |
238 | delivers "false"). |
56 | syscall has been executed asynchronously. |
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57 | |
239 | |
58 | All functions that expect a filehandle will also accept a file |
240 | Some requests (such as "aio_readdir") pass the actual results and |
59 | descriptor. |
241 | communicate failures by passing "undef". |
60 | |
242 | |
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243 | All functions expecting a filehandle keep a copy of the filehandle |
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244 | internally until the request has finished. |
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245 | |
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246 | All functions return request objects of type IO::AIO::REQ that allow |
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247 | further manipulation of those requests while they are in-flight. |
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248 | |
61 | The filenames you pass to these routines *must* be absolute. The reason |
249 | The pathnames you pass to these routines *should* be absolute. The |
62 | is that at the time the request is being executed, the current working |
250 | reason for this is that at the time the request is being executed, the |
63 | directory could have changed. Alternatively, you can make sure that you |
251 | current working directory could have changed. Alternatively, you can |
64 | never change the current working directory. |
252 | make sure that you never change the current working directory anywhere |
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253 | in the program and then use relative paths. You can also take advantage |
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254 | of IO::AIOs working directory abstraction, that lets you specify paths |
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255 | relative to some previously-opened "working directory object" - see the |
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256 | description of the "IO::AIO::WD" class later in this document. |
65 | |
257 | |
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258 | To encode pathnames as octets, either make sure you either: a) always |
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259 | pass in filenames you got from outside (command line, readdir etc.) |
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260 | without tinkering, b) are in your native filesystem encoding, c) use the |
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261 | Encode module and encode your pathnames to the locale (or other) |
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262 | encoding in effect in the user environment, d) use |
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263 | Glib::filename_from_unicode on unicode filenames or e) use something |
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264 | else to ensure your scalar has the correct contents. |
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265 | |
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266 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
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267 | handles correctly whether it is set or not. |
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268 | |
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269 | AIO REQUEST FUNCTIONS |
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270 | $prev_pri = aioreq_pri [$pri] |
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271 | Returns the priority value that would be used for the next request |
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272 | and, if $pri is given, sets the priority for the next aio request. |
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273 | |
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274 | The default priority is 0, the minimum and maximum priorities are -4 |
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275 | and 4, respectively. Requests with higher priority will be serviced |
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276 | first. |
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277 | |
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278 | The priority will be reset to 0 after each call to one of the |
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279 | "aio_*" functions. |
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280 | |
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281 | Example: open a file with low priority, then read something from it |
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282 | with higher priority so the read request is serviced before other |
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283 | low priority open requests (potentially spamming the cache): |
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284 | |
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285 | aioreq_pri -3; |
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286 | aio_open ..., sub { |
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287 | return unless $_[0]; |
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288 | |
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289 | aioreq_pri -2; |
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290 | aio_read $_[0], ..., sub { |
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291 | ... |
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292 | }; |
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293 | }; |
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294 | |
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295 | aioreq_nice $pri_adjust |
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296 | Similar to "aioreq_pri", but subtracts the given value from the |
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297 | current priority, so the effect is cumulative. |
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298 | |
66 | aio_open $pathname, $flags, $mode, $callback |
299 | aio_open $pathname, $flags, $mode, $callback->($fh) |
67 | Asynchronously open or create a file and call the callback with a |
300 | Asynchronously open or create a file and call the callback with a |
68 | newly created filehandle for the file. |
301 | newly created filehandle for the file (or "undef" in case of an |
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302 | error). |
69 | |
303 | |
70 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
304 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
71 | above, for an explanation. |
305 | above, for an explanation. |
72 | |
306 | |
73 | The $mode argument is a bitmask. See the "Fcntl" module for a list. |
307 | The $flags argument is a bitmask. See the "Fcntl" module for a list. |
74 | They are the same as used in "sysopen". |
308 | They are the same as used by "sysopen". |
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309 | |
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310 | Likewise, $mode specifies the mode of the newly created file, if it |
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311 | didn't exist and "O_CREAT" has been given, just like perl's |
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312 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
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313 | create new files, and 0666 or 0777 if you do). Note that the $mode |
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314 | will be modified by the umask in effect then the request is being |
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315 | executed, so better never change the umask. |
75 | |
316 | |
76 | Example: |
317 | Example: |
77 | |
318 | |
78 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
319 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
79 | if ($_[0]) { |
320 | if ($_[0]) { |
80 | print "open successful, fh is $_[0]\n"; |
321 | print "open successful, fh is $_[0]\n"; |
81 | ... |
322 | ... |
82 | } else { |
323 | } else { |
83 | die "open failed: $!\n"; |
324 | die "open failed: $!\n"; |
84 | } |
325 | } |
85 | }; |
326 | }; |
86 | |
327 | |
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328 | In addition to all the common open modes/flags ("O_RDONLY", |
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329 | "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and |
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330 | "O_APPEND"), the following POSIX and non-POSIX constants are |
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331 | available (missing ones on your system are, as usual, 0): |
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332 | |
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333 | "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", |
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334 | "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", |
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335 | "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". |
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336 | |
87 | aio_close $fh, $callback |
337 | aio_close $fh, $callback->($status) |
88 | Asynchronously close a file and call the callback with the result |
338 | Asynchronously close a file and call the callback with the result |
89 | code. *WARNING:* although accepted, you should not pass in a perl |
339 | code. |
90 | filehandle here, as perl will likely close the file descriptor |
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91 | itself when the filehandle is destroyed. Normally, you can safely |
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92 | call perls "close" or just let filehandles go out of scope. |
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93 | |
340 | |
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341 | Unfortunately, you can't do this to perl. Perl *insists* very |
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342 | strongly on closing the file descriptor associated with the |
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343 | filehandle itself. |
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344 | |
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345 | Therefore, "aio_close" will not close the filehandle - instead it |
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346 | will use dup2 to overwrite the file descriptor with the write-end of |
|
|
347 | a pipe (the pipe fd will be created on demand and will be cached). |
|
|
348 | |
|
|
349 | Or in other words: the file descriptor will be closed, but it will |
|
|
350 | not be free for reuse until the perl filehandle is closed. |
|
|
351 | |
|
|
352 | aio_seek $fh, $offset, $whence, $callback->($offs) |
|
|
353 | Seeks the filehandle to the new $offset, similarly to perl's |
|
|
354 | "sysseek". The $whence can use the traditional values (0 for |
|
|
355 | "IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for |
|
|
356 | "IO::AIO::SEEK_END"). |
|
|
357 | |
|
|
358 | The resulting absolute offset will be passed to the callback, or -1 |
|
|
359 | in case of an error. |
|
|
360 | |
|
|
361 | In theory, the $whence constants could be different than the |
|
|
362 | corresponding values from Fcntl, but perl guarantees they are the |
|
|
363 | same, so don't panic. |
|
|
364 | |
|
|
365 | As a GNU/Linux (and maybe Solaris) extension, also the constants |
|
|
366 | "IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they |
|
|
367 | could be found. No guarantees about suitability for use in |
|
|
368 | "aio_seek" or Perl's "sysseek" can be made though, although I would |
|
|
369 | naively assume they "just work". |
|
|
370 | |
94 | aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
371 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
95 | aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
372 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
96 | Reads or writes "length" bytes from the specified "fh" and "offset" |
373 | Reads or writes $length bytes from or to the specified $fh and |
97 | into the scalar given by "data" and offset "dataoffset" and calls |
374 | $offset into the scalar given by $data and offset $dataoffset and |
98 | the callback without the actual number of bytes read (or -1 on |
375 | calls the callback without the actual number of bytes read (or -1 on |
99 | error, just like the syscall). |
376 | error, just like the syscall). |
100 | |
377 | |
|
|
378 | "aio_read" will, like "sysread", shrink or grow the $data scalar to |
|
|
379 | offset plus the actual number of bytes read. |
|
|
380 | |
|
|
381 | If $offset is undefined, then the current file descriptor offset |
|
|
382 | will be used (and updated), otherwise the file descriptor offset |
|
|
383 | will not be changed by these calls. |
|
|
384 | |
|
|
385 | If $length is undefined in "aio_write", use the remaining length of |
|
|
386 | $data. |
|
|
387 | |
|
|
388 | If $dataoffset is less than zero, it will be counted from the end of |
|
|
389 | $data. |
|
|
390 | |
|
|
391 | The $data scalar *MUST NOT* be modified in any way while the request |
|
|
392 | is outstanding. Modifying it can result in segfaults or World War |
|
|
393 | III (if the necessary/optional hardware is installed). |
|
|
394 | |
101 | Example: Read 15 bytes at offset 7 into scalar $buffer, strating at |
395 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
102 | offset 0 within the scalar: |
396 | offset 0 within the scalar: |
103 | |
397 | |
104 | aio_read $fh, 7, 15, $buffer, 0, sub { |
398 | aio_read $fh, 7, 15, $buffer, 0, sub { |
105 | $_[0] > 0 or die "read error: $!"; |
399 | $_[0] > 0 or die "read error: $!"; |
106 | print "read $_[0] bytes: <$buffer>\n"; |
400 | print "read $_[0] bytes: <$buffer>\n"; |
107 | }; |
401 | }; |
108 | |
402 | |
|
|
403 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
|
|
404 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
|
|
405 | reading at byte offset $in_offset, and starts writing at the current |
|
|
406 | file offset of $out_fh. Because of that, it is not safe to issue |
|
|
407 | more than one "aio_sendfile" per $out_fh, as they will interfere |
|
|
408 | with each other. The same $in_fh works fine though, as this function |
|
|
409 | does not move or use the file offset of $in_fh. |
|
|
410 | |
|
|
411 | Please note that "aio_sendfile" can read more bytes from $in_fh than |
|
|
412 | are written, and there is no way to find out how many more bytes |
|
|
413 | have been read from "aio_sendfile" alone, as "aio_sendfile" only |
|
|
414 | provides the number of bytes written to $out_fh. Only if the result |
|
|
415 | value equals $length one can assume that $length bytes have been |
|
|
416 | read. |
|
|
417 | |
|
|
418 | Unlike with other "aio_" functions, it makes a lot of sense to use |
|
|
419 | "aio_sendfile" on non-blocking sockets, as long as one end |
|
|
420 | (typically the $in_fh) is a file - the file I/O will then be |
|
|
421 | asynchronous, while the socket I/O will be non-blocking. Note, |
|
|
422 | however, that you can run into a trap where "aio_sendfile" reads |
|
|
423 | some data with readahead, then fails to write all data, and when the |
|
|
424 | socket is ready the next time, the data in the cache is already |
|
|
425 | lost, forcing "aio_sendfile" to again hit the disk. Explicit |
|
|
426 | "aio_read" + "aio_write" let's you better control resource usage. |
|
|
427 | |
|
|
428 | This call tries to make use of a native "sendfile"-like syscall to |
|
|
429 | provide zero-copy operation. For this to work, $out_fh should refer |
|
|
430 | to a socket, and $in_fh should refer to an mmap'able file. |
|
|
431 | |
|
|
432 | If a native sendfile cannot be found or it fails with "ENOSYS", |
|
|
433 | "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or |
|
|
434 | "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on |
|
|
435 | any type of filehandle regardless of the limitations of the |
|
|
436 | operating system. |
|
|
437 | |
|
|
438 | As native sendfile syscalls (as practically any non-POSIX interface |
|
|
439 | hacked together in a hurry to improve benchmark numbers) tend to be |
|
|
440 | rather buggy on many systems, this implementation tries to work |
|
|
441 | around some known bugs in Linux and FreeBSD kernels (probably |
|
|
442 | others, too), but that might fail, so you really really should check |
|
|
443 | the return value of "aio_sendfile" - fewre bytes than expected might |
|
|
444 | have been transferred. |
|
|
445 | |
109 | aio_readahead $fh,$offset,$length, $callback |
446 | aio_readahead $fh,$offset,$length, $callback->($retval) |
110 | Asynchronously reads the specified byte range into the page cache, |
|
|
111 | using the "readahead" syscall. If that syscall doesn't exist the |
|
|
112 | status will be -1 and $! is set to ENOSYS. |
|
|
113 | |
|
|
114 | readahead() populates the page cache with data from a file so that |
447 | "aio_readahead" populates the page cache with data from a file so |
115 | subsequent reads from that file will not block on disk I/O. The |
448 | that subsequent reads from that file will not block on disk I/O. The |
116 | $offset argument specifies the starting point from which data is to |
449 | $offset argument specifies the starting point from which data is to |
117 | be read and $length specifies the number of bytes to be read. I/O is |
450 | be read and $length specifies the number of bytes to be read. I/O is |
118 | performed in whole pages, so that offset is effectively rounded down |
451 | performed in whole pages, so that offset is effectively rounded down |
119 | to a page boundary and bytes are read up to the next page boundary |
452 | to a page boundary and bytes are read up to the next page boundary |
120 | greater than or equal to (off-set+length). aio_readahead() does not |
453 | greater than or equal to (off-set+length). "aio_readahead" does not |
121 | read beyond the end of the file. The current file offset of the file |
454 | read beyond the end of the file. The current file offset of the file |
122 | is left unchanged. |
455 | is left unchanged. |
123 | |
456 | |
|
|
457 | If that syscall doesn't exist (likely if your OS isn't Linux) it |
|
|
458 | will be emulated by simply reading the data, which would have a |
|
|
459 | similar effect. |
|
|
460 | |
124 | aio_stat $fh_or_path, $callback |
461 | aio_stat $fh_or_path, $callback->($status) |
125 | aio_lstat $fh, $callback |
462 | aio_lstat $fh, $callback->($status) |
126 | Works like perl's "stat" or "lstat" in void context. The callback |
463 | Works like perl's "stat" or "lstat" in void context. The callback |
127 | will be called after the stat and the results will be available |
464 | will be called after the stat and the results will be available |
128 | using "stat _" or "-s _" etc... |
465 | using "stat _" or "-s _" etc... |
129 | |
466 | |
130 | The pathname passed to "aio_stat" must be absolute. See API NOTES, |
467 | The pathname passed to "aio_stat" must be absolute. See API NOTES, |
… | |
… | |
133 | Currently, the stats are always 64-bit-stats, i.e. instead of |
470 | Currently, the stats are always 64-bit-stats, i.e. instead of |
134 | returning an error when stat'ing a large file, the results will be |
471 | returning an error when stat'ing a large file, the results will be |
135 | silently truncated unless perl itself is compiled with large file |
472 | silently truncated unless perl itself is compiled with large file |
136 | support. |
473 | support. |
137 | |
474 | |
|
|
475 | To help interpret the mode and dev/rdev stat values, IO::AIO offers |
|
|
476 | the following constants and functions (if not implemented, the |
|
|
477 | constants will be 0 and the functions will either "croak" or fall |
|
|
478 | back on traditional behaviour). |
|
|
479 | |
|
|
480 | "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", |
|
|
481 | "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", |
|
|
482 | "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". |
|
|
483 | |
138 | Example: Print the length of /etc/passwd: |
484 | Example: Print the length of /etc/passwd: |
139 | |
485 | |
140 | aio_stat "/etc/passwd", sub { |
486 | aio_stat "/etc/passwd", sub { |
141 | $_[0] and die "stat failed: $!"; |
487 | $_[0] and die "stat failed: $!"; |
142 | print "size is ", -s _, "\n"; |
488 | print "size is ", -s _, "\n"; |
143 | }; |
489 | }; |
144 | |
490 | |
|
|
491 | aio_statvfs $fh_or_path, $callback->($statvfs) |
|
|
492 | Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on |
|
|
493 | whether a file handle or path was passed. |
|
|
494 | |
|
|
495 | On success, the callback is passed a hash reference with the |
|
|
496 | following members: "bsize", "frsize", "blocks", "bfree", "bavail", |
|
|
497 | "files", "ffree", "favail", "fsid", "flag" and "namemax". On |
|
|
498 | failure, "undef" is passed. |
|
|
499 | |
|
|
500 | The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY" |
|
|
501 | and "ST_NOSUID". |
|
|
502 | |
|
|
503 | The following non-POSIX IO::AIO::ST_* flag masks are defined to |
|
|
504 | their correct value when available, or to 0 on systems that do not |
|
|
505 | support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS", |
|
|
506 | "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE", |
|
|
507 | "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME". |
|
|
508 | |
|
|
509 | Example: stat "/wd" and dump out the data if successful. |
|
|
510 | |
|
|
511 | aio_statvfs "/wd", sub { |
|
|
512 | my $f = $_[0] |
|
|
513 | or die "statvfs: $!"; |
|
|
514 | |
|
|
515 | use Data::Dumper; |
|
|
516 | say Dumper $f; |
|
|
517 | }; |
|
|
518 | |
|
|
519 | # result: |
|
|
520 | { |
|
|
521 | bsize => 1024, |
|
|
522 | bfree => 4333064312, |
|
|
523 | blocks => 10253828096, |
|
|
524 | files => 2050765568, |
|
|
525 | flag => 4096, |
|
|
526 | favail => 2042092649, |
|
|
527 | bavail => 4333064312, |
|
|
528 | ffree => 2042092649, |
|
|
529 | namemax => 255, |
|
|
530 | frsize => 1024, |
|
|
531 | fsid => 1810 |
|
|
532 | } |
|
|
533 | |
|
|
534 | Here is a (likely partial - send me updates!) list of fsid values |
|
|
535 | used by Linux - it is safe to hardcode these when $^O is "linux": |
|
|
536 | |
|
|
537 | 0x0000adf5 adfs |
|
|
538 | 0x0000adff affs |
|
|
539 | 0x5346414f afs |
|
|
540 | 0x09041934 anon-inode filesystem |
|
|
541 | 0x00000187 autofs |
|
|
542 | 0x42465331 befs |
|
|
543 | 0x1badface bfs |
|
|
544 | 0x42494e4d binfmt_misc |
|
|
545 | 0x9123683e btrfs |
|
|
546 | 0x0027e0eb cgroupfs |
|
|
547 | 0xff534d42 cifs |
|
|
548 | 0x73757245 coda |
|
|
549 | 0x012ff7b7 coh |
|
|
550 | 0x28cd3d45 cramfs |
|
|
551 | 0x453dcd28 cramfs-wend (wrong endianness) |
|
|
552 | 0x64626720 debugfs |
|
|
553 | 0x00001373 devfs |
|
|
554 | 0x00001cd1 devpts |
|
|
555 | 0x0000f15f ecryptfs |
|
|
556 | 0x00414a53 efs |
|
|
557 | 0x0000137d ext |
|
|
558 | 0x0000ef53 ext2/ext3 |
|
|
559 | 0x0000ef51 ext2 |
|
|
560 | 0x00004006 fat |
|
|
561 | 0x65735546 fuseblk |
|
|
562 | 0x65735543 fusectl |
|
|
563 | 0x0bad1dea futexfs |
|
|
564 | 0x01161970 gfs2 |
|
|
565 | 0x47504653 gpfs |
|
|
566 | 0x00004244 hfs |
|
|
567 | 0xf995e849 hpfs |
|
|
568 | 0x958458f6 hugetlbfs |
|
|
569 | 0x2bad1dea inotifyfs |
|
|
570 | 0x00009660 isofs |
|
|
571 | 0x000072b6 jffs2 |
|
|
572 | 0x3153464a jfs |
|
|
573 | 0x6b414653 k-afs |
|
|
574 | 0x0bd00bd0 lustre |
|
|
575 | 0x0000137f minix |
|
|
576 | 0x0000138f minix 30 char names |
|
|
577 | 0x00002468 minix v2 |
|
|
578 | 0x00002478 minix v2 30 char names |
|
|
579 | 0x00004d5a minix v3 |
|
|
580 | 0x19800202 mqueue |
|
|
581 | 0x00004d44 msdos |
|
|
582 | 0x0000564c novell |
|
|
583 | 0x00006969 nfs |
|
|
584 | 0x6e667364 nfsd |
|
|
585 | 0x00003434 nilfs |
|
|
586 | 0x5346544e ntfs |
|
|
587 | 0x00009fa1 openprom |
|
|
588 | 0x7461636F ocfs2 |
|
|
589 | 0x00009fa0 proc |
|
|
590 | 0x6165676c pstorefs |
|
|
591 | 0x0000002f qnx4 |
|
|
592 | 0x858458f6 ramfs |
|
|
593 | 0x52654973 reiserfs |
|
|
594 | 0x00007275 romfs |
|
|
595 | 0x67596969 rpc_pipefs |
|
|
596 | 0x73636673 securityfs |
|
|
597 | 0xf97cff8c selinux |
|
|
598 | 0x0000517b smb |
|
|
599 | 0x534f434b sockfs |
|
|
600 | 0x73717368 squashfs |
|
|
601 | 0x62656572 sysfs |
|
|
602 | 0x012ff7b6 sysv2 |
|
|
603 | 0x012ff7b5 sysv4 |
|
|
604 | 0x01021994 tmpfs |
|
|
605 | 0x15013346 udf |
|
|
606 | 0x00011954 ufs |
|
|
607 | 0x54190100 ufs byteswapped |
|
|
608 | 0x00009fa2 usbdevfs |
|
|
609 | 0x01021997 v9fs |
|
|
610 | 0xa501fcf5 vxfs |
|
|
611 | 0xabba1974 xenfs |
|
|
612 | 0x012ff7b4 xenix |
|
|
613 | 0x58465342 xfs |
|
|
614 | 0x012fd16d xia |
|
|
615 | |
|
|
616 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
|
|
617 | Works like perl's "utime" function (including the special case of |
|
|
618 | $atime and $mtime being undef). Fractional times are supported if |
|
|
619 | the underlying syscalls support them. |
|
|
620 | |
|
|
621 | When called with a pathname, uses utimes(2) if available, otherwise |
|
|
622 | utime(2). If called on a file descriptor, uses futimes(2) if |
|
|
623 | available, otherwise returns ENOSYS, so this is not portable. |
|
|
624 | |
|
|
625 | Examples: |
|
|
626 | |
|
|
627 | # set atime and mtime to current time (basically touch(1)): |
|
|
628 | aio_utime "path", undef, undef; |
|
|
629 | # set atime to current time and mtime to beginning of the epoch: |
|
|
630 | aio_utime "path", time, undef; # undef==0 |
|
|
631 | |
|
|
632 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
|
|
633 | Works like perl's "chown" function, except that "undef" for either |
|
|
634 | $uid or $gid is being interpreted as "do not change" (but -1 can |
|
|
635 | also be used). |
|
|
636 | |
|
|
637 | Examples: |
|
|
638 | |
|
|
639 | # same as "chown root path" in the shell: |
|
|
640 | aio_chown "path", 0, -1; |
|
|
641 | # same as above: |
|
|
642 | aio_chown "path", 0, undef; |
|
|
643 | |
|
|
644 | aio_truncate $fh_or_path, $offset, $callback->($status) |
|
|
645 | Works like truncate(2) or ftruncate(2). |
|
|
646 | |
|
|
647 | aio_allocate $fh, $mode, $offset, $len, $callback->($status) |
|
|
648 | Allocates or freed disk space according to the $mode argument. See |
|
|
649 | the linux "fallocate" docuemntation for details. |
|
|
650 | |
|
|
651 | $mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to |
|
|
652 | allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE | |
|
|
653 | IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range. |
|
|
654 | |
|
|
655 | The file system block size used by "fallocate" is presumably the |
|
|
656 | "f_bsize" returned by "statvfs". |
|
|
657 | |
|
|
658 | If "fallocate" isn't available or cannot be emulated (currently no |
|
|
659 | emulation will be attempted), passes -1 and sets $! to "ENOSYS". |
|
|
660 | |
|
|
661 | aio_chmod $fh_or_path, $mode, $callback->($status) |
|
|
662 | Works like perl's "chmod" function. |
|
|
663 | |
145 | aio_unlink $pathname, $callback |
664 | aio_unlink $pathname, $callback->($status) |
146 | Asynchronously unlink (delete) a file and call the callback with the |
665 | Asynchronously unlink (delete) a file and call the callback with the |
147 | result code. |
666 | result code. |
148 | |
667 | |
|
|
668 | aio_mknod $pathname, $mode, $dev, $callback->($status) |
|
|
669 | [EXPERIMENTAL] |
|
|
670 | |
|
|
671 | Asynchronously create a device node (or fifo). See mknod(2). |
|
|
672 | |
|
|
673 | The only (POSIX-) portable way of calling this function is: |
|
|
674 | |
|
|
675 | aio_mknod $pathname, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
|
|
676 | |
|
|
677 | See "aio_stat" for info about some potentially helpful extra |
|
|
678 | constants and functions. |
|
|
679 | |
|
|
680 | aio_link $srcpath, $dstpath, $callback->($status) |
|
|
681 | Asynchronously create a new link to the existing object at $srcpath |
|
|
682 | at the path $dstpath and call the callback with the result code. |
|
|
683 | |
|
|
684 | aio_symlink $srcpath, $dstpath, $callback->($status) |
|
|
685 | Asynchronously create a new symbolic link to the existing object at |
|
|
686 | $srcpath at the path $dstpath and call the callback with the result |
|
|
687 | code. |
|
|
688 | |
|
|
689 | aio_readlink $pathname, $callback->($link) |
|
|
690 | Asynchronously read the symlink specified by $path and pass it to |
|
|
691 | the callback. If an error occurs, nothing or undef gets passed to |
|
|
692 | the callback. |
|
|
693 | |
|
|
694 | aio_realpath $pathname, $callback->($path) |
|
|
695 | Asynchronously make the path absolute and resolve any symlinks in |
|
|
696 | $path. The resulting path only consists of directories (same as |
|
|
697 | Cwd::realpath). |
|
|
698 | |
|
|
699 | This request can be used to get the absolute path of the current |
|
|
700 | working directory by passing it a path of . (a single dot). |
|
|
701 | |
|
|
702 | aio_rename $srcpath, $dstpath, $callback->($status) |
|
|
703 | Asynchronously rename the object at $srcpath to $dstpath, just as |
|
|
704 | rename(2) and call the callback with the result code. |
|
|
705 | |
|
|
706 | On systems that support the AIO::WD working directory abstraction |
|
|
707 | natively, the case "[$wd, "."]" as $srcpath is specialcased - |
|
|
708 | instead of failing, "rename" is called on the absolute path of $wd. |
|
|
709 | |
|
|
710 | aio_mkdir $pathname, $mode, $callback->($status) |
|
|
711 | Asynchronously mkdir (create) a directory and call the callback with |
|
|
712 | the result code. $mode will be modified by the umask at the time the |
|
|
713 | request is executed, so do not change your umask. |
|
|
714 | |
|
|
715 | aio_rmdir $pathname, $callback->($status) |
|
|
716 | Asynchronously rmdir (delete) a directory and call the callback with |
|
|
717 | the result code. |
|
|
718 | |
|
|
719 | On systems that support the AIO::WD working directory abstraction |
|
|
720 | natively, the case "[$wd, "."]" is specialcased - instead of |
|
|
721 | failing, "rmdir" is called on the absolute path of $wd. |
|
|
722 | |
|
|
723 | aio_readdir $pathname, $callback->($entries) |
|
|
724 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
|
|
725 | entire directory (i.e. opendir + readdir + closedir). The entries |
|
|
726 | will not be sorted, and will NOT include the "." and ".." entries. |
|
|
727 | |
|
|
728 | The callback is passed a single argument which is either "undef" or |
|
|
729 | an array-ref with the filenames. |
|
|
730 | |
|
|
731 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
|
|
732 | Quite similar to "aio_readdir", but the $flags argument allows one |
|
|
733 | to tune behaviour and output format. In case of an error, $entries |
|
|
734 | will be "undef". |
|
|
735 | |
|
|
736 | The flags are a combination of the following constants, ORed |
|
|
737 | together (the flags will also be passed to the callback, possibly |
|
|
738 | modified): |
|
|
739 | |
|
|
740 | IO::AIO::READDIR_DENTS |
|
|
741 | When this flag is off, then the callback gets an arrayref |
|
|
742 | consisting of names only (as with "aio_readdir"), otherwise it |
|
|
743 | gets an arrayref with "[$name, $type, $inode]" arrayrefs, each |
|
|
744 | describing a single directory entry in more detail. |
|
|
745 | |
|
|
746 | $name is the name of the entry. |
|
|
747 | |
|
|
748 | $type is one of the "IO::AIO::DT_xxx" constants: |
|
|
749 | |
|
|
750 | "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", |
|
|
751 | "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", |
|
|
752 | "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". |
|
|
753 | |
|
|
754 | "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If |
|
|
755 | you need to know, you have to run stat yourself. Also, for speed |
|
|
756 | reasons, the $type scalars are read-only: you can not modify |
|
|
757 | them. |
|
|
758 | |
|
|
759 | $inode is the inode number (which might not be exact on systems |
|
|
760 | with 64 bit inode numbers and 32 bit perls). This field has |
|
|
761 | unspecified content on systems that do not deliver the inode |
|
|
762 | information. |
|
|
763 | |
|
|
764 | IO::AIO::READDIR_DIRS_FIRST |
|
|
765 | When this flag is set, then the names will be returned in an |
|
|
766 | order where likely directories come first, in optimal stat |
|
|
767 | order. This is useful when you need to quickly find directories, |
|
|
768 | or you want to find all directories while avoiding to stat() |
|
|
769 | each entry. |
|
|
770 | |
|
|
771 | If the system returns type information in readdir, then this is |
|
|
772 | used to find directories directly. Otherwise, likely directories |
|
|
773 | are names beginning with ".", or otherwise names with no dots, |
|
|
774 | of which names with short names are tried first. |
|
|
775 | |
|
|
776 | IO::AIO::READDIR_STAT_ORDER |
|
|
777 | When this flag is set, then the names will be returned in an |
|
|
778 | order suitable for stat()'ing each one. That is, when you plan |
|
|
779 | to stat() all files in the given directory, then the returned |
|
|
780 | order will likely be fastest. |
|
|
781 | |
|
|
782 | If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are |
|
|
783 | specified, then the likely dirs come first, resulting in a less |
|
|
784 | optimal stat order. |
|
|
785 | |
|
|
786 | IO::AIO::READDIR_FOUND_UNKNOWN |
|
|
787 | This flag should not be set when calling "aio_readdirx". |
|
|
788 | Instead, it is being set by "aio_readdirx", when any of the |
|
|
789 | $type's found were "IO::AIO::DT_UNKNOWN". The absence of this |
|
|
790 | flag therefore indicates that all $type's are known, which can |
|
|
791 | be used to speed up some algorithms. |
|
|
792 | |
|
|
793 | aio_load $pathname, $data, $callback->($status) |
|
|
794 | This is a composite request that tries to fully load the given file |
|
|
795 | into memory. Status is the same as with aio_read. |
|
|
796 | |
|
|
797 | aio_copy $srcpath, $dstpath, $callback->($status) |
|
|
798 | Try to copy the *file* (directories not supported as either source |
|
|
799 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
800 | a status of 0 (ok) or -1 (error, see $!). |
|
|
801 | |
|
|
802 | This is a composite request that creates the destination file with |
|
|
803 | mode 0200 and copies the contents of the source file into it using |
|
|
804 | "aio_sendfile", followed by restoring atime, mtime, access mode and |
|
|
805 | uid/gid, in that order. |
|
|
806 | |
|
|
807 | If an error occurs, the partial destination file will be unlinked, |
|
|
808 | if possible, except when setting atime, mtime, access mode and |
|
|
809 | uid/gid, where errors are being ignored. |
|
|
810 | |
|
|
811 | aio_move $srcpath, $dstpath, $callback->($status) |
|
|
812 | Try to move the *file* (directories not supported as either source |
|
|
813 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
814 | a status of 0 (ok) or -1 (error, see $!). |
|
|
815 | |
|
|
816 | This is a composite request that tries to rename(2) the file first; |
|
|
817 | if rename fails with "EXDEV", it copies the file with "aio_copy" |
|
|
818 | and, if that is successful, unlinks the $srcpath. |
|
|
819 | |
|
|
820 | aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs) |
|
|
821 | Scans a directory (similar to "aio_readdir") but additionally tries |
|
|
822 | to efficiently separate the entries of directory $path into two sets |
|
|
823 | of names, directories you can recurse into (directories), and ones |
|
|
824 | you cannot recurse into (everything else, including symlinks to |
|
|
825 | directories). |
|
|
826 | |
|
|
827 | "aio_scandir" is a composite request that creates of many sub |
|
|
828 | requests_ $maxreq specifies the maximum number of outstanding aio |
|
|
829 | requests that this function generates. If it is "<= 0", then a |
|
|
830 | suitable default will be chosen (currently 4). |
|
|
831 | |
|
|
832 | On error, the callback is called without arguments, otherwise it |
|
|
833 | receives two array-refs with path-relative entry names. |
|
|
834 | |
|
|
835 | Example: |
|
|
836 | |
|
|
837 | aio_scandir $dir, 0, sub { |
|
|
838 | my ($dirs, $nondirs) = @_; |
|
|
839 | print "real directories: @$dirs\n"; |
|
|
840 | print "everything else: @$nondirs\n"; |
|
|
841 | }; |
|
|
842 | |
|
|
843 | Implementation notes. |
|
|
844 | |
|
|
845 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
|
|
846 | can. |
|
|
847 | |
|
|
848 | If readdir returns file type information, then this is used directly |
|
|
849 | to find directories. |
|
|
850 | |
|
|
851 | Otherwise, after reading the directory, the modification time, size |
|
|
852 | etc. of the directory before and after the readdir is checked, and |
|
|
853 | if they match (and isn't the current time), the link count will be |
|
|
854 | used to decide how many entries are directories (if >= 2). |
|
|
855 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
856 | assumed. |
|
|
857 | |
|
|
858 | Then entries will be sorted into likely directories a non-initial |
|
|
859 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
|
|
860 | every entry plus an appended "/." will be "stat"'ed, likely |
|
|
861 | directories first, in order of their inode numbers. If that |
|
|
862 | succeeds, it assumes that the entry is a directory or a symlink to |
|
|
863 | directory (which will be checked separately). This is often faster |
|
|
864 | than stat'ing the entry itself because filesystems might detect the |
|
|
865 | type of the entry without reading the inode data (e.g. ext2fs |
|
|
866 | filetype feature), even on systems that cannot return the filetype |
|
|
867 | information on readdir. |
|
|
868 | |
|
|
869 | If the known number of directories (link count - 2) has been |
|
|
870 | reached, the rest of the entries is assumed to be non-directories. |
|
|
871 | |
|
|
872 | This only works with certainty on POSIX (= UNIX) filesystems, which |
|
|
873 | fortunately are the vast majority of filesystems around. |
|
|
874 | |
|
|
875 | It will also likely work on non-POSIX filesystems with reduced |
|
|
876 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
877 | disables the directory counting heuristic. |
|
|
878 | |
|
|
879 | aio_rmtree $pathname, $callback->($status) |
|
|
880 | Delete a directory tree starting (and including) $path, return the |
|
|
881 | status of the final "rmdir" only. This is a composite request that |
|
|
882 | uses "aio_scandir" to recurse into and rmdir directories, and unlink |
|
|
883 | everything else. |
|
|
884 | |
|
|
885 | aio_sync $callback->($status) |
|
|
886 | Asynchronously call sync and call the callback when finished. |
|
|
887 | |
149 | aio_fsync $fh, $callback |
888 | aio_fsync $fh, $callback->($status) |
150 | Asynchronously call fsync on the given filehandle and call the |
889 | Asynchronously call fsync on the given filehandle and call the |
151 | callback with the fsync result code. |
890 | callback with the fsync result code. |
152 | |
891 | |
153 | aio_fdatasync $fh, $callback |
892 | aio_fdatasync $fh, $callback->($status) |
154 | Asynchronously call fdatasync on the given filehandle and call the |
893 | Asynchronously call fdatasync on the given filehandle and call the |
155 | callback with the fdatasync result code. |
894 | callback with the fdatasync result code. |
156 | |
895 | |
|
|
896 | If this call isn't available because your OS lacks it or it couldn't |
|
|
897 | be detected, it will be emulated by calling "fsync" instead. |
|
|
898 | |
|
|
899 | aio_syncfs $fh, $callback->($status) |
|
|
900 | Asynchronously call the syncfs syscall to sync the filesystem |
|
|
901 | associated to the given filehandle and call the callback with the |
|
|
902 | syncfs result code. If syncfs is not available, calls sync(), but |
|
|
903 | returns -1 and sets errno to "ENOSYS" nevertheless. |
|
|
904 | |
|
|
905 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
|
|
906 | Sync the data portion of the file specified by $offset and $length |
|
|
907 | to disk (but NOT the metadata), by calling the Linux-specific |
|
|
908 | sync_file_range call. If sync_file_range is not available or it |
|
|
909 | returns ENOSYS, then fdatasync or fsync is being substituted. |
|
|
910 | |
|
|
911 | $flags can be a combination of |
|
|
912 | "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", |
|
|
913 | "IO::AIO::SYNC_FILE_RANGE_WRITE" and |
|
|
914 | "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range |
|
|
915 | manpage for details. |
|
|
916 | |
|
|
917 | aio_pathsync $pathname, $callback->($status) |
|
|
918 | This request tries to open, fsync and close the given path. This is |
|
|
919 | a composite request intended to sync directories after directory |
|
|
920 | operations (E.g. rename). This might not work on all operating |
|
|
921 | systems or have any specific effect, but usually it makes sure that |
|
|
922 | directory changes get written to disc. It works for anything that |
|
|
923 | can be opened for read-only, not just directories. |
|
|
924 | |
|
|
925 | Future versions of this function might fall back to other methods |
|
|
926 | when "fsync" on the directory fails (such as calling "sync"). |
|
|
927 | |
|
|
928 | Passes 0 when everything went ok, and -1 on error. |
|
|
929 | |
|
|
930 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
931 | $callback->($status) |
|
|
932 | This is a rather advanced IO::AIO call, which only works on |
|
|
933 | mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it |
|
|
934 | also works on data scalars managed by the Sys::Mmap or Mmap modules, |
|
|
935 | note that the scalar must only be modified in-place while an aio |
|
|
936 | operation is pending on it). |
|
|
937 | |
|
|
938 | It calls the "msync" function of your OS, if available, with the |
|
|
939 | memory area starting at $offset in the string and ending $length |
|
|
940 | bytes later. If $length is negative, counts from the end, and if |
|
|
941 | $length is "undef", then it goes till the end of the string. The |
|
|
942 | flags can be a combination of "IO::AIO::MS_ASYNC", |
|
|
943 | "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". |
|
|
944 | |
|
|
945 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
946 | $callback->($status) |
|
|
947 | This is a rather advanced IO::AIO call, which works best on |
|
|
948 | mmap(2)ed scalars. |
|
|
949 | |
|
|
950 | It touches (reads or writes) all memory pages in the specified range |
|
|
951 | inside the scalar. All caveats and parameters are the same as for |
|
|
952 | "aio_msync", above, except for flags, which must be either 0 (which |
|
|
953 | reads all pages and ensures they are instantiated) or |
|
|
954 | "IO::AIO::MT_MODIFY", which modifies the memory pages (by reading |
|
|
955 | and writing an octet from it, which dirties the page). |
|
|
956 | |
|
|
957 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
|
|
958 | This is a rather advanced IO::AIO call, which works best on |
|
|
959 | mmap(2)ed scalars. |
|
|
960 | |
|
|
961 | It reads in all the pages of the underlying storage into memory (if |
|
|
962 | any) and locks them, so they are not getting swapped/paged out or |
|
|
963 | removed. |
|
|
964 | |
|
|
965 | If $length is undefined, then the scalar will be locked till the |
|
|
966 | end. |
|
|
967 | |
|
|
968 | On systems that do not implement "mlock", this function returns -1 |
|
|
969 | and sets errno to "ENOSYS". |
|
|
970 | |
|
|
971 | Note that the corresponding "munlock" is synchronous and is |
|
|
972 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
973 | |
|
|
974 | Example: open a file, mmap and mlock it - both will be undone when |
|
|
975 | $data gets destroyed. |
|
|
976 | |
|
|
977 | open my $fh, "<", $path or die "$path: $!"; |
|
|
978 | my $data; |
|
|
979 | IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
|
|
980 | aio_mlock $data; # mlock in background |
|
|
981 | |
|
|
982 | aio_mlockall $flags, $callback->($status) |
|
|
983 | Calls the "mlockall" function with the given $flags (a combination |
|
|
984 | of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). |
|
|
985 | |
|
|
986 | On systems that do not implement "mlockall", this function returns |
|
|
987 | -1 and sets errno to "ENOSYS". |
|
|
988 | |
|
|
989 | Note that the corresponding "munlockall" is synchronous and is |
|
|
990 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
991 | |
|
|
992 | Example: asynchronously lock all current and future pages into |
|
|
993 | memory. |
|
|
994 | |
|
|
995 | aio_mlockall IO::AIO::MCL_FUTURE; |
|
|
996 | |
|
|
997 | aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents) |
|
|
998 | Queries the extents of the given file (by calling the Linux "FIEMAP" |
|
|
999 | ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for |
|
|
1000 | details). If the ioctl is not available on your OS, then this |
|
|
1001 | request will fail with "ENOSYS". |
|
|
1002 | |
|
|
1003 | $start is the starting offset to query extents for, $length is the |
|
|
1004 | size of the range to query - if it is "undef", then the whole file |
|
|
1005 | will be queried. |
|
|
1006 | |
|
|
1007 | $flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or |
|
|
1008 | "IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is |
|
|
1009 | also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to |
|
|
1010 | query the data portion. |
|
|
1011 | |
|
|
1012 | $count is the maximum number of extent records to return. If it is |
|
|
1013 | "undef", then IO::AIO queries all extents of the range. As a very |
|
|
1014 | special case, if it is 0, then the callback receives the number of |
|
|
1015 | extents instead of the extents themselves (which is unreliable, see |
|
|
1016 | below). |
|
|
1017 | |
|
|
1018 | If an error occurs, the callback receives no arguments. The special |
|
|
1019 | "errno" value "IO::AIO::EBADR" is available to test for flag errors. |
|
|
1020 | |
|
|
1021 | Otherwise, the callback receives an array reference with extent |
|
|
1022 | structures. Each extent structure is an array reference itself, with |
|
|
1023 | the following members: |
|
|
1024 | |
|
|
1025 | [$logical, $physical, $length, $flags] |
|
|
1026 | |
|
|
1027 | Flags is any combination of the following flag values (typically |
|
|
1028 | either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)): |
|
|
1029 | |
|
|
1030 | "IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN", |
|
|
1031 | "IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED", |
|
|
1032 | "IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED", |
|
|
1033 | "IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED", |
|
|
1034 | "IO::AIO::FIEMAP_EXTENT_DATA_INLINE", |
|
|
1035 | "IO::AIO::FIEMAP_EXTENT_DATA_TAIL", |
|
|
1036 | "IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED" |
|
|
1037 | or "IO::AIO::FIEMAP_EXTENT_SHARED". |
|
|
1038 | |
|
|
1039 | At the time of this writing (Linux 3.2), this requets is unreliable |
|
|
1040 | unless $count is "undef", as the kernel has all sorts of bugs |
|
|
1041 | preventing it to return all extents of a range for files with large |
|
|
1042 | number of extents. The code works around all these issues if $count |
|
|
1043 | is undef. |
|
|
1044 | |
|
|
1045 | aio_group $callback->(...) |
|
|
1046 | This is a very special aio request: Instead of doing something, it |
|
|
1047 | is a container for other aio requests, which is useful if you want |
|
|
1048 | to bundle many requests into a single, composite, request with a |
|
|
1049 | definite callback and the ability to cancel the whole request with |
|
|
1050 | its subrequests. |
|
|
1051 | |
|
|
1052 | Returns an object of class IO::AIO::GRP. See its documentation below |
|
|
1053 | for more info. |
|
|
1054 | |
|
|
1055 | Example: |
|
|
1056 | |
|
|
1057 | my $grp = aio_group sub { |
|
|
1058 | print "all stats done\n"; |
|
|
1059 | }; |
|
|
1060 | |
|
|
1061 | add $grp |
|
|
1062 | (aio_stat ...), |
|
|
1063 | (aio_stat ...), |
|
|
1064 | ...; |
|
|
1065 | |
|
|
1066 | aio_nop $callback->() |
|
|
1067 | This is a special request - it does nothing in itself and is only |
|
|
1068 | used for side effects, such as when you want to add a dummy request |
|
|
1069 | to a group so that finishing the requests in the group depends on |
|
|
1070 | executing the given code. |
|
|
1071 | |
|
|
1072 | While this request does nothing, it still goes through the execution |
|
|
1073 | phase and still requires a worker thread. Thus, the callback will |
|
|
1074 | not be executed immediately but only after other requests in the |
|
|
1075 | queue have entered their execution phase. This can be used to |
|
|
1076 | measure request latency. |
|
|
1077 | |
|
|
1078 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
|
|
1079 | Mainly used for debugging and benchmarking, this aio request puts |
|
|
1080 | one of the request workers to sleep for the given time. |
|
|
1081 | |
|
|
1082 | While it is theoretically handy to have simple I/O scheduling |
|
|
1083 | requests like sleep and file handle readable/writable, the overhead |
|
|
1084 | this creates is immense (it blocks a thread for a long time) so do |
|
|
1085 | not use this function except to put your application under |
|
|
1086 | artificial I/O pressure. |
|
|
1087 | |
|
|
1088 | IO::AIO::WD - multiple working directories |
|
|
1089 | Your process only has one current working directory, which is used by |
|
|
1090 | all threads. This makes it hard to use relative paths (some other |
|
|
1091 | component could call "chdir" at any time, and it is hard to control when |
|
|
1092 | the path will be used by IO::AIO). |
|
|
1093 | |
|
|
1094 | One solution for this is to always use absolute paths. This usually |
|
|
1095 | works, but can be quite slow (the kernel has to walk the whole path on |
|
|
1096 | every access), and can also be a hassle to implement. |
|
|
1097 | |
|
|
1098 | Newer POSIX systems have a number of functions (openat, fdopendir, |
|
|
1099 | futimensat and so on) that make it possible to specify working |
|
|
1100 | directories per operation. |
|
|
1101 | |
|
|
1102 | For portability, and because the clowns who "designed", or shall I |
|
|
1103 | write, perpetrated this new interface were obviously half-drunk, this |
|
|
1104 | abstraction cannot be perfect, though. |
|
|
1105 | |
|
|
1106 | IO::AIO allows you to convert directory paths into a so-called |
|
|
1107 | IO::AIO::WD object. This object stores the canonicalised, absolute |
|
|
1108 | version of the path, and on systems that allow it, also a directory file |
|
|
1109 | descriptor. |
|
|
1110 | |
|
|
1111 | Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat" |
|
|
1112 | or "aio_unlink"), one can specify an array reference with an IO::AIO::WD |
|
|
1113 | object and a pathname instead (or the IO::AIO::WD object alone, which |
|
|
1114 | gets interpreted as "[$wd, "."]"). If the pathname is absolute, the |
|
|
1115 | IO::AIO::WD object is ignored, otherwise the pathname is resolved |
|
|
1116 | relative to that IO::AIO::WD object. |
|
|
1117 | |
|
|
1118 | For example, to get a wd object for /etc and then stat passwd inside, |
|
|
1119 | you would write: |
|
|
1120 | |
|
|
1121 | aio_wd "/etc", sub { |
|
|
1122 | my $etcdir = shift; |
|
|
1123 | |
|
|
1124 | # although $etcdir can be undef on error, there is generally no reason |
|
|
1125 | # to check for errors here, as aio_stat will fail with ENOENT |
|
|
1126 | # when $etcdir is undef. |
|
|
1127 | |
|
|
1128 | aio_stat [$etcdir, "passwd"], sub { |
|
|
1129 | # yay |
|
|
1130 | }; |
|
|
1131 | }; |
|
|
1132 | |
|
|
1133 | That "aio_wd" is a request and not a normal function shows that creating |
|
|
1134 | an IO::AIO::WD object is itself a potentially blocking operation, which |
|
|
1135 | is why it is done asynchronously. |
|
|
1136 | |
|
|
1137 | To stat the directory obtained with "aio_wd" above, one could write |
|
|
1138 | either of the following three request calls: |
|
|
1139 | |
|
|
1140 | aio_lstat "/etc" , sub { ... # pathname as normal string |
|
|
1141 | aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself) |
|
|
1142 | aio_lstat $wd , sub { ... # shorthand for the previous |
|
|
1143 | |
|
|
1144 | As with normal pathnames, IO::AIO keeps a copy of the working directory |
|
|
1145 | object and the pathname string, so you could write the following without |
|
|
1146 | causing any issues due to $path getting reused: |
|
|
1147 | |
|
|
1148 | my $path = [$wd, undef]; |
|
|
1149 | |
|
|
1150 | for my $name (qw(abc def ghi)) { |
|
|
1151 | $path->[1] = $name; |
|
|
1152 | aio_stat $path, sub { |
|
|
1153 | # ... |
|
|
1154 | }; |
|
|
1155 | } |
|
|
1156 | |
|
|
1157 | There are some caveats: when directories get renamed (or deleted), the |
|
|
1158 | pathname string doesn't change, so will point to the new directory (or |
|
|
1159 | nowhere at all), while the directory fd, if available on the system, |
|
|
1160 | will still point to the original directory. Most functions accepting a |
|
|
1161 | pathname will use the directory fd on newer systems, and the string on |
|
|
1162 | older systems. Some functions (such as realpath) will always rely on the |
|
|
1163 | string form of the pathname. |
|
|
1164 | |
|
|
1165 | So this functionality is mainly useful to get some protection against |
|
|
1166 | "chdir", to easily get an absolute path out of a relative path for |
|
|
1167 | future reference, and to speed up doing many operations in the same |
|
|
1168 | directory (e.g. when stat'ing all files in a directory). |
|
|
1169 | |
|
|
1170 | The following functions implement this working directory abstraction: |
|
|
1171 | |
|
|
1172 | aio_wd $pathname, $callback->($wd) |
|
|
1173 | Asynchonously canonicalise the given pathname and convert it to an |
|
|
1174 | IO::AIO::WD object representing it. If possible and supported on the |
|
|
1175 | system, also open a directory fd to speed up pathname resolution |
|
|
1176 | relative to this working directory. |
|
|
1177 | |
|
|
1178 | If something goes wrong, then "undef" is passwd to the callback |
|
|
1179 | instead of a working directory object and $! is set appropriately. |
|
|
1180 | Since passing "undef" as working directory component of a pathname |
|
|
1181 | fails the request with "ENOENT", there is often no need for error |
|
|
1182 | checking in the "aio_wd" callback, as future requests using the |
|
|
1183 | value will fail in the expected way. |
|
|
1184 | |
|
|
1185 | IO::AIO::CWD |
|
|
1186 | This is a compiletime constant (object) that represents the process |
|
|
1187 | current working directory. |
|
|
1188 | |
|
|
1189 | Specifying this object as working directory object for a pathname is |
|
|
1190 | as if the pathname would be specified directly, without a directory |
|
|
1191 | object. For example, these calls are functionally identical: |
|
|
1192 | |
|
|
1193 | aio_stat "somefile", sub { ... }; |
|
|
1194 | aio_stat [IO::AIO::CWD, "somefile"], sub { ... }; |
|
|
1195 | |
|
|
1196 | To recover the path associated with an IO::AIO::WD object, you can use |
|
|
1197 | "aio_realpath": |
|
|
1198 | |
|
|
1199 | aio_realpath $wd, sub { |
|
|
1200 | warn "path is $_[0]\n"; |
|
|
1201 | }; |
|
|
1202 | |
|
|
1203 | Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir" |
|
|
1204 | sometimes, fall back to using an absolue path. |
|
|
1205 | |
|
|
1206 | IO::AIO::REQ CLASS |
|
|
1207 | All non-aggregate "aio_*" functions return an object of this class when |
|
|
1208 | called in non-void context. |
|
|
1209 | |
|
|
1210 | cancel $req |
|
|
1211 | Cancels the request, if possible. Has the effect of skipping |
|
|
1212 | execution when entering the execute state and skipping calling the |
|
|
1213 | callback when entering the the result state, but will leave the |
|
|
1214 | request otherwise untouched (with the exception of readdir). That |
|
|
1215 | means that requests that currently execute will not be stopped and |
|
|
1216 | resources held by the request will not be freed prematurely. |
|
|
1217 | |
|
|
1218 | cb $req $callback->(...) |
|
|
1219 | Replace (or simply set) the callback registered to the request. |
|
|
1220 | |
|
|
1221 | IO::AIO::GRP CLASS |
|
|
1222 | This class is a subclass of IO::AIO::REQ, so all its methods apply to |
|
|
1223 | objects of this class, too. |
|
|
1224 | |
|
|
1225 | A IO::AIO::GRP object is a special request that can contain multiple |
|
|
1226 | other aio requests. |
|
|
1227 | |
|
|
1228 | You create one by calling the "aio_group" constructing function with a |
|
|
1229 | callback that will be called when all contained requests have entered |
|
|
1230 | the "done" state: |
|
|
1231 | |
|
|
1232 | my $grp = aio_group sub { |
|
|
1233 | print "all requests are done\n"; |
|
|
1234 | }; |
|
|
1235 | |
|
|
1236 | You add requests by calling the "add" method with one or more |
|
|
1237 | "IO::AIO::REQ" objects: |
|
|
1238 | |
|
|
1239 | $grp->add (aio_unlink "..."); |
|
|
1240 | |
|
|
1241 | add $grp aio_stat "...", sub { |
|
|
1242 | $_[0] or return $grp->result ("error"); |
|
|
1243 | |
|
|
1244 | # add another request dynamically, if first succeeded |
|
|
1245 | add $grp aio_open "...", sub { |
|
|
1246 | $grp->result ("ok"); |
|
|
1247 | }; |
|
|
1248 | }; |
|
|
1249 | |
|
|
1250 | This makes it very easy to create composite requests (see the source of |
|
|
1251 | "aio_move" for an application) that work and feel like simple requests. |
|
|
1252 | |
|
|
1253 | * The IO::AIO::GRP objects will be cleaned up during calls to |
|
|
1254 | "IO::AIO::poll_cb", just like any other request. |
|
|
1255 | |
|
|
1256 | * They can be canceled like any other request. Canceling will cancel |
|
|
1257 | not only the request itself, but also all requests it contains. |
|
|
1258 | |
|
|
1259 | * They can also can also be added to other IO::AIO::GRP objects. |
|
|
1260 | |
|
|
1261 | * You must not add requests to a group from within the group callback |
|
|
1262 | (or any later time). |
|
|
1263 | |
|
|
1264 | Their lifetime, simplified, looks like this: when they are empty, they |
|
|
1265 | will finish very quickly. If they contain only requests that are in the |
|
|
1266 | "done" state, they will also finish. Otherwise they will continue to |
|
|
1267 | exist. |
|
|
1268 | |
|
|
1269 | That means after creating a group you have some time to add requests |
|
|
1270 | (precisely before the callback has been invoked, which is only done |
|
|
1271 | within the "poll_cb"). And in the callbacks of those requests, you can |
|
|
1272 | add further requests to the group. And only when all those requests have |
|
|
1273 | finished will the the group itself finish. |
|
|
1274 | |
|
|
1275 | add $grp ... |
|
|
1276 | $grp->add (...) |
|
|
1277 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
|
|
1278 | be added, including other groups, as long as you do not create |
|
|
1279 | circular dependencies. |
|
|
1280 | |
|
|
1281 | Returns all its arguments. |
|
|
1282 | |
|
|
1283 | $grp->cancel_subs |
|
|
1284 | Cancel all subrequests and clears any feeder, but not the group |
|
|
1285 | request itself. Useful when you queued a lot of events but got a |
|
|
1286 | result early. |
|
|
1287 | |
|
|
1288 | The group request will finish normally (you cannot add requests to |
|
|
1289 | the group). |
|
|
1290 | |
|
|
1291 | $grp->result (...) |
|
|
1292 | Set the result value(s) that will be passed to the group callback |
|
|
1293 | when all subrequests have finished and set the groups errno to the |
|
|
1294 | current value of errno (just like calling "errno" without an error |
|
|
1295 | number). By default, no argument will be passed and errno is zero. |
|
|
1296 | |
|
|
1297 | $grp->errno ([$errno]) |
|
|
1298 | Sets the group errno value to $errno, or the current value of errno |
|
|
1299 | when the argument is missing. |
|
|
1300 | |
|
|
1301 | Every aio request has an associated errno value that is restored |
|
|
1302 | when the callback is invoked. This method lets you change this value |
|
|
1303 | from its default (0). |
|
|
1304 | |
|
|
1305 | Calling "result" will also set errno, so make sure you either set $! |
|
|
1306 | before the call to "result", or call c<errno> after it. |
|
|
1307 | |
|
|
1308 | feed $grp $callback->($grp) |
|
|
1309 | Sets a feeder/generator on this group: every group can have an |
|
|
1310 | attached generator that generates requests if idle. The idea behind |
|
|
1311 | this is that, although you could just queue as many requests as you |
|
|
1312 | want in a group, this might starve other requests for a potentially |
|
|
1313 | long time. For example, "aio_scandir" might generate hundreds of |
|
|
1314 | thousands of "aio_stat" requests, delaying any later requests for a |
|
|
1315 | long time. |
|
|
1316 | |
|
|
1317 | To avoid this, and allow incremental generation of requests, you can |
|
|
1318 | instead a group and set a feeder on it that generates those |
|
|
1319 | requests. The feed callback will be called whenever there are few |
|
|
1320 | enough (see "limit", below) requests active in the group itself and |
|
|
1321 | is expected to queue more requests. |
|
|
1322 | |
|
|
1323 | The feed callback can queue as many requests as it likes (i.e. "add" |
|
|
1324 | does not impose any limits). |
|
|
1325 | |
|
|
1326 | If the feed does not queue more requests when called, it will be |
|
|
1327 | automatically removed from the group. |
|
|
1328 | |
|
|
1329 | If the feed limit is 0 when this method is called, it will be set to |
|
|
1330 | 2 automatically. |
|
|
1331 | |
|
|
1332 | Example: |
|
|
1333 | |
|
|
1334 | # stat all files in @files, but only ever use four aio requests concurrently: |
|
|
1335 | |
|
|
1336 | my $grp = aio_group sub { print "finished\n" }; |
|
|
1337 | limit $grp 4; |
|
|
1338 | feed $grp sub { |
|
|
1339 | my $file = pop @files |
|
|
1340 | or return; |
|
|
1341 | |
|
|
1342 | add $grp aio_stat $file, sub { ... }; |
|
|
1343 | }; |
|
|
1344 | |
|
|
1345 | limit $grp $num |
|
|
1346 | Sets the feeder limit for the group: The feeder will be called |
|
|
1347 | whenever the group contains less than this many requests. |
|
|
1348 | |
|
|
1349 | Setting the limit to 0 will pause the feeding process. |
|
|
1350 | |
|
|
1351 | The default value for the limit is 0, but note that setting a feeder |
|
|
1352 | automatically bumps it up to 2. |
|
|
1353 | |
157 | SUPPORT FUNCTIONS |
1354 | SUPPORT FUNCTIONS |
|
|
1355 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
158 | $fileno = IO::AIO::poll_fileno |
1356 | $fileno = IO::AIO::poll_fileno |
159 | Return the *request result pipe filehandle*. This filehandle must be |
1357 | Return the *request result pipe file descriptor*. This filehandle |
160 | polled for reading by some mechanism outside this module (e.g. Event |
1358 | must be polled for reading by some mechanism outside this module |
161 | or select, see below). If the pipe becomes readable you have to call |
1359 | (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the |
162 | "poll_cb" to check the results. |
1360 | pipe becomes readable you have to call "poll_cb" to check the |
|
|
1361 | results. |
163 | |
1362 | |
164 | See "poll_cb" for an example. |
1363 | See "poll_cb" for an example. |
165 | |
1364 | |
166 | IO::AIO::poll_cb |
1365 | IO::AIO::poll_cb |
167 | Process all outstanding events on the result pipe. You have to call |
1366 | Process some requests that have reached the result phase (i.e. they |
168 | this regularly. Returns the number of events processed. Returns |
1367 | have been executed but the results are not yet reported). You have |
|
|
1368 | to call this "regularly" to finish outstanding requests. |
|
|
1369 | |
|
|
1370 | Returns 0 if all events could be processed (or there were no events |
|
|
1371 | to process), or -1 if it returned earlier for whatever reason. |
169 | immediately when no events are outstanding. |
1372 | Returns immediately when no events are outstanding. The amount of |
|
|
1373 | events processed depends on the settings of "IO::AIO::max_poll_req", |
|
|
1374 | "IO::AIO::max_poll_time" and "IO::AIO::max_outstanding". |
170 | |
1375 | |
171 | You can use Event to multiplex, e.g.: |
1376 | If not all requests were processed for whatever reason, the poll |
|
|
1377 | file descriptor will still be ready when "poll_cb" returns, so |
|
|
1378 | normally you don't have to do anything special to have it called |
|
|
1379 | later. |
|
|
1380 | |
|
|
1381 | Apart from calling "IO::AIO::poll_cb" when the event filehandle |
|
|
1382 | becomes ready, it can be beneficial to call this function from loops |
|
|
1383 | which submit a lot of requests, to make sure the results get |
|
|
1384 | processed when they become available and not just when the loop is |
|
|
1385 | finished and the event loop takes over again. This function returns |
|
|
1386 | very fast when there are no outstanding requests. |
|
|
1387 | |
|
|
1388 | Example: Install an Event watcher that automatically calls |
|
|
1389 | IO::AIO::poll_cb with high priority (more examples can be found in |
|
|
1390 | the SYNOPSIS section, at the top of this document): |
172 | |
1391 | |
173 | Event->io (fd => IO::AIO::poll_fileno, |
1392 | Event->io (fd => IO::AIO::poll_fileno, |
174 | poll => 'r', async => 1, |
1393 | poll => 'r', async => 1, |
175 | cb => \&IO::AIO::poll_cb); |
1394 | cb => \&IO::AIO::poll_cb); |
176 | |
1395 | |
177 | IO::AIO::poll_wait |
1396 | IO::AIO::poll_wait |
178 | Wait till the result filehandle becomes ready for reading (simply |
1397 | Wait until either at least one request is in the result phase or no |
179 | does a select on the filehandle. This is useful if you want to |
1398 | requests are outstanding anymore. |
180 | synchronously wait for some requests to finish). |
1399 | |
|
|
1400 | This is useful if you want to synchronously wait for some requests |
|
|
1401 | to become ready, without actually handling them. |
181 | |
1402 | |
182 | See "nreqs" for an example. |
1403 | See "nreqs" for an example. |
183 | |
1404 | |
|
|
1405 | IO::AIO::poll |
|
|
1406 | Waits until some requests have been handled. |
|
|
1407 | |
|
|
1408 | Returns the number of requests processed, but is otherwise strictly |
|
|
1409 | equivalent to: |
|
|
1410 | |
|
|
1411 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1412 | |
184 | IO::AIO::nreqs |
1413 | IO::AIO::flush |
185 | Returns the number of requests currently outstanding. |
1414 | Wait till all outstanding AIO requests have been handled. |
186 | |
1415 | |
187 | Example: wait till there are no outstanding requests anymore: |
1416 | Strictly equivalent to: |
188 | |
1417 | |
189 | IO::AIO::poll_wait, IO::AIO::poll_cb |
1418 | IO::AIO::poll_wait, IO::AIO::poll_cb |
190 | while IO::AIO::nreqs; |
1419 | while IO::AIO::nreqs; |
191 | |
1420 | |
|
|
1421 | IO::AIO::max_poll_reqs $nreqs |
|
|
1422 | IO::AIO::max_poll_time $seconds |
|
|
1423 | These set the maximum number of requests (default 0, meaning |
|
|
1424 | infinity) that are being processed by "IO::AIO::poll_cb" in one |
|
|
1425 | call, respectively the maximum amount of time (default 0, meaning |
|
|
1426 | infinity) spent in "IO::AIO::poll_cb" to process requests (more |
|
|
1427 | correctly the mininum amount of time "poll_cb" is allowed to use). |
|
|
1428 | |
|
|
1429 | Setting "max_poll_time" to a non-zero value creates an overhead of |
|
|
1430 | one syscall per request processed, which is not normally a problem |
|
|
1431 | unless your callbacks are really really fast or your OS is really |
|
|
1432 | really slow (I am not mentioning Solaris here). Using |
|
|
1433 | "max_poll_reqs" incurs no overhead. |
|
|
1434 | |
|
|
1435 | Setting these is useful if you want to ensure some level of |
|
|
1436 | interactiveness when perl is not fast enough to process all requests |
|
|
1437 | in time. |
|
|
1438 | |
|
|
1439 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
|
|
1440 | |
|
|
1441 | Example: Install an Event watcher that automatically calls |
|
|
1442 | IO::AIO::poll_cb with low priority, to ensure that other parts of |
|
|
1443 | the program get the CPU sometimes even under high AIO load. |
|
|
1444 | |
|
|
1445 | # try not to spend much more than 0.1s in poll_cb |
|
|
1446 | IO::AIO::max_poll_time 0.1; |
|
|
1447 | |
|
|
1448 | # use a low priority so other tasks have priority |
|
|
1449 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1450 | poll => 'r', nice => 1, |
|
|
1451 | cb => &IO::AIO::poll_cb); |
|
|
1452 | |
|
|
1453 | CONTROLLING THE NUMBER OF THREADS |
192 | IO::AIO::min_parallel $nthreads |
1454 | IO::AIO::min_parallel $nthreads |
193 | Set the minimum number of AIO threads to $nthreads. The default is |
1455 | Set the minimum number of AIO threads to $nthreads. The current |
194 | 1, which means a single asynchronous operation can be done at one |
1456 | default is 8, which means eight asynchronous operations can execute |
195 | time (the number of outstanding operations, however, is unlimited). |
1457 | concurrently at any one time (the number of outstanding requests, |
|
|
1458 | however, is unlimited). |
196 | |
1459 | |
|
|
1460 | IO::AIO starts threads only on demand, when an AIO request is queued |
|
|
1461 | and no free thread exists. Please note that queueing up a hundred |
|
|
1462 | requests can create demand for a hundred threads, even if it turns |
|
|
1463 | out that everything is in the cache and could have been processed |
|
|
1464 | faster by a single thread. |
|
|
1465 | |
197 | It is recommended to keep the number of threads low, as some Linux |
1466 | It is recommended to keep the number of threads relatively low, as |
198 | kernel versions will scale negatively with the number of threads |
1467 | some Linux kernel versions will scale negatively with the number of |
199 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
1468 | threads (higher parallelity => MUCH higher latency). With current |
200 | versions, 4-32 threads should be fine. |
1469 | Linux 2.6 versions, 4-32 threads should be fine. |
201 | |
1470 | |
202 | Under normal circumstances you don't need to call this function, as |
1471 | Under most circumstances you don't need to call this function, as |
203 | this module automatically starts some threads (the exact number |
1472 | the module selects a default that is suitable for low to moderate |
204 | might change, and is currently 4). |
1473 | load. |
205 | |
1474 | |
206 | IO::AIO::max_parallel $nthreads |
1475 | IO::AIO::max_parallel $nthreads |
207 | Sets the maximum number of AIO threads to $nthreads. If more than |
1476 | Sets the maximum number of AIO threads to $nthreads. If more than |
208 | the specified number of threads are currently running, kill them. |
1477 | the specified number of threads are currently running, this function |
209 | This function blocks until the limit is reached. |
1478 | kills them. This function blocks until the limit is reached. |
|
|
1479 | |
|
|
1480 | While $nthreads are zero, aio requests get queued but not executed |
|
|
1481 | until the number of threads has been increased again. |
210 | |
1482 | |
211 | This module automatically runs "max_parallel 0" at program end, to |
1483 | This module automatically runs "max_parallel 0" at program end, to |
212 | ensure that all threads are killed and that there are no outstanding |
1484 | ensure that all threads are killed and that there are no outstanding |
213 | requests. |
1485 | requests. |
214 | |
1486 | |
215 | Under normal circumstances you don't need to call this function. |
1487 | Under normal circumstances you don't need to call this function. |
216 | |
1488 | |
|
|
1489 | IO::AIO::max_idle $nthreads |
|
|
1490 | Limit the number of threads (default: 4) that are allowed to idle |
|
|
1491 | (i.e., threads that did not get a request to process within the idle |
|
|
1492 | timeout (default: 10 seconds). That means if a thread becomes idle |
|
|
1493 | while $nthreads other threads are also idle, it will free its |
|
|
1494 | resources and exit. |
|
|
1495 | |
|
|
1496 | This is useful when you allow a large number of threads (e.g. 100 or |
|
|
1497 | 1000) to allow for extremely high load situations, but want to free |
|
|
1498 | resources under normal circumstances (1000 threads can easily |
|
|
1499 | consume 30MB of RAM). |
|
|
1500 | |
|
|
1501 | The default is probably ok in most situations, especially if thread |
|
|
1502 | creation is fast. If thread creation is very slow on your system you |
|
|
1503 | might want to use larger values. |
|
|
1504 | |
|
|
1505 | IO::AIO::idle_timeout $seconds |
|
|
1506 | Sets the minimum idle timeout (default 10) after which worker |
|
|
1507 | threads are allowed to exit. SEe "IO::AIO::max_idle". |
|
|
1508 | |
217 | $oldnreqs = IO::AIO::max_outstanding $nreqs |
1509 | IO::AIO::max_outstanding $maxreqs |
218 | Sets the maximum number of outstanding requests to $nreqs. If you |
1510 | Sets the maximum number of outstanding requests to $nreqs. If you do |
219 | try to queue up more than this number of requests, the caller will |
1511 | queue up more than this number of requests, the next call to |
|
|
1512 | "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as |
|
|
1513 | "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is |
|
|
1514 | no longer exceeded. |
|
|
1515 | |
|
|
1516 | In other words, this setting does not enforce a queue limit, but can |
|
|
1517 | be used to make poll functions block if the limit is exceeded. |
|
|
1518 | |
|
|
1519 | This is a very bad function to use in interactive programs because |
|
|
1520 | it blocks, and a bad way to reduce concurrency because it is |
|
|
1521 | inexact: Better use an "aio_group" together with a feed callback. |
|
|
1522 | |
|
|
1523 | It's main use is in scripts without an event loop - when you want to |
|
|
1524 | stat a lot of files, you can write somehting like this: |
|
|
1525 | |
|
|
1526 | IO::AIO::max_outstanding 32; |
|
|
1527 | |
|
|
1528 | for my $path (...) { |
|
|
1529 | aio_stat $path , ...; |
|
|
1530 | IO::AIO::poll_cb; |
|
|
1531 | } |
|
|
1532 | |
|
|
1533 | IO::AIO::flush; |
|
|
1534 | |
|
|
1535 | The call to "poll_cb" inside the loop will normally return |
|
|
1536 | instantly, but as soon as more thna 32 reqeusts are in-flight, it |
220 | block until some requests have been handled. |
1537 | will block until some requests have been handled. This keeps the |
|
|
1538 | loop from pushing a large number of "aio_stat" requests onto the |
|
|
1539 | queue. |
221 | |
1540 | |
222 | The default is very large, so normally there is no practical limit. |
1541 | The default value for "max_outstanding" is very large, so there is |
223 | If you queue up many requests in a loop it it often improves speed |
1542 | no practical limit on the number of outstanding requests. |
224 | if you set this to a relatively low number, such as 100. |
|
|
225 | |
1543 | |
226 | Under normal circumstances you don't need to call this function. |
1544 | STATISTICAL INFORMATION |
|
|
1545 | IO::AIO::nreqs |
|
|
1546 | Returns the number of requests currently in the ready, execute or |
|
|
1547 | pending states (i.e. for which their callback has not been invoked |
|
|
1548 | yet). |
|
|
1549 | |
|
|
1550 | Example: wait till there are no outstanding requests anymore: |
|
|
1551 | |
|
|
1552 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1553 | while IO::AIO::nreqs; |
|
|
1554 | |
|
|
1555 | IO::AIO::nready |
|
|
1556 | Returns the number of requests currently in the ready state (not yet |
|
|
1557 | executed). |
|
|
1558 | |
|
|
1559 | IO::AIO::npending |
|
|
1560 | Returns the number of requests currently in the pending state |
|
|
1561 | (executed, but not yet processed by poll_cb). |
|
|
1562 | |
|
|
1563 | MISCELLANEOUS FUNCTIONS |
|
|
1564 | IO::AIO implements some functions that might be useful, but are not |
|
|
1565 | asynchronous. |
|
|
1566 | |
|
|
1567 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
|
|
1568 | Calls the "eio_sendfile_sync" function, which is like |
|
|
1569 | "aio_sendfile", but is blocking (this makes most sense if you know |
|
|
1570 | the input data is likely cached already and the output filehandle is |
|
|
1571 | set to non-blocking operations). |
|
|
1572 | |
|
|
1573 | Returns the number of bytes copied, or -1 on error. |
|
|
1574 | |
|
|
1575 | IO::AIO::fadvise $fh, $offset, $len, $advice |
|
|
1576 | Simply calls the "posix_fadvise" function (see its manpage for |
|
|
1577 | details). The following advice constants are available: |
|
|
1578 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
|
|
1579 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
|
|
1580 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
|
|
1581 | |
|
|
1582 | On systems that do not implement "posix_fadvise", this function |
|
|
1583 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
|
|
1584 | |
|
|
1585 | IO::AIO::madvise $scalar, $offset, $len, $advice |
|
|
1586 | Simply calls the "posix_madvise" function (see its manpage for |
|
|
1587 | details). The following advice constants are available: |
|
|
1588 | "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", |
|
|
1589 | "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", |
|
|
1590 | "IO::AIO::MADV_DONTNEED". |
|
|
1591 | |
|
|
1592 | On systems that do not implement "posix_madvise", this function |
|
|
1593 | returns ENOSYS, otherwise the return value of "posix_madvise". |
|
|
1594 | |
|
|
1595 | IO::AIO::mprotect $scalar, $offset, $len, $protect |
|
|
1596 | Simply calls the "mprotect" function on the preferably AIO::mmap'ed |
|
|
1597 | $scalar (see its manpage for details). The following protect |
|
|
1598 | constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", |
|
|
1599 | "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". |
|
|
1600 | |
|
|
1601 | On systems that do not implement "mprotect", this function returns |
|
|
1602 | ENOSYS, otherwise the return value of "mprotect". |
|
|
1603 | |
|
|
1604 | IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
|
|
1605 | Memory-maps a file (or anonymous memory range) and attaches it to |
|
|
1606 | the given $scalar, which will act like a string scalar. Returns true |
|
|
1607 | on success, and false otherwise. |
|
|
1608 | |
|
|
1609 | The only operations allowed on the scalar are "substr"/"vec" that |
|
|
1610 | don't change the string length, and most read-only operations such |
|
|
1611 | as copying it or searching it with regexes and so on. |
|
|
1612 | |
|
|
1613 | Anything else is unsafe and will, at best, result in memory leaks. |
|
|
1614 | |
|
|
1615 | The memory map associated with the $scalar is automatically removed |
|
|
1616 | when the $scalar is destroyed, or when the "IO::AIO::mmap" or |
|
|
1617 | "IO::AIO::munmap" functions are called. |
|
|
1618 | |
|
|
1619 | This calls the "mmap"(2) function internally. See your system's |
|
|
1620 | manual page for details on the $length, $prot and $flags parameters. |
|
|
1621 | |
|
|
1622 | The $length must be larger than zero and smaller than the actual |
|
|
1623 | filesize. |
|
|
1624 | |
|
|
1625 | $prot is a combination of "IO::AIO::PROT_NONE", |
|
|
1626 | "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or |
|
|
1627 | "IO::AIO::PROT_WRITE", |
|
|
1628 | |
|
|
1629 | $flags can be a combination of "IO::AIO::MAP_SHARED" or |
|
|
1630 | "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when |
|
|
1631 | not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" |
|
|
1632 | (which is set to "MAP_ANON" if your system only provides this |
|
|
1633 | constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", |
|
|
1634 | "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or |
|
|
1635 | "IO::AIO::MAP_NONBLOCK" |
|
|
1636 | |
|
|
1637 | If $fh is "undef", then a file descriptor of -1 is passed. |
|
|
1638 | |
|
|
1639 | $offset is the offset from the start of the file - it generally must |
|
|
1640 | be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. |
|
|
1641 | |
|
|
1642 | Example: |
|
|
1643 | |
|
|
1644 | use Digest::MD5; |
|
|
1645 | use IO::AIO; |
|
|
1646 | |
|
|
1647 | open my $fh, "<verybigfile" |
|
|
1648 | or die "$!"; |
|
|
1649 | |
|
|
1650 | IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh |
|
|
1651 | or die "verybigfile: $!"; |
|
|
1652 | |
|
|
1653 | my $fast_md5 = md5 $data; |
|
|
1654 | |
|
|
1655 | IO::AIO::munmap $scalar |
|
|
1656 | Removes a previous mmap and undefines the $scalar. |
|
|
1657 | |
|
|
1658 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
|
|
1659 | Calls the "munlock" function, undoing the effects of a previous |
|
|
1660 | "aio_mlock" call (see its description for details). |
|
|
1661 | |
|
|
1662 | IO::AIO::munlockall |
|
|
1663 | Calls the "munlockall" function. |
|
|
1664 | |
|
|
1665 | On systems that do not implement "munlockall", this function returns |
|
|
1666 | ENOSYS, otherwise the return value of "munlockall". |
|
|
1667 | |
|
|
1668 | IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags |
|
|
1669 | Calls the GNU/Linux splice(2) syscall, if available. If $r_off or |
|
|
1670 | $w_off are "undef", then "NULL" is passed for these, otherwise they |
|
|
1671 | should be the file offset. |
|
|
1672 | |
|
|
1673 | $r_fh and $w_fh should not refer to the same file, as splice might |
|
|
1674 | silently corrupt the data in this case. |
|
|
1675 | |
|
|
1676 | The following symbol flag values are available: |
|
|
1677 | "IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK", |
|
|
1678 | "IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT". |
|
|
1679 | |
|
|
1680 | See the splice(2) manpage for details. |
|
|
1681 | |
|
|
1682 | IO::AIO::tee $r_fh, $w_fh, $length, $flags |
|
|
1683 | Calls the GNU/Linux tee(2) syscall, see it's manpage and the |
|
|
1684 | description for "IO::AIO::splice" above for details. |
|
|
1685 | |
|
|
1686 | $actual_size = IO::AIO::pipesize $r_fh[, $new_size] |
|
|
1687 | Attempts to query or change the pipe buffer size. Obviously works |
|
|
1688 | only on pipes, and currently works only on GNU/Linux systems, and |
|
|
1689 | fails with -1/"ENOSYS" everywhere else. If anybody knows how to |
|
|
1690 | influence pipe buffer size on other systems, drop me a note. |
|
|
1691 | |
|
|
1692 | EVENT LOOP INTEGRATION |
|
|
1693 | It is recommended to use AnyEvent::AIO to integrate IO::AIO |
|
|
1694 | automatically into many event loops: |
|
|
1695 | |
|
|
1696 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
|
|
1697 | use AnyEvent::AIO; |
|
|
1698 | |
|
|
1699 | You can also integrate IO::AIO manually into many event loops, here are |
|
|
1700 | some examples of how to do this: |
|
|
1701 | |
|
|
1702 | # EV integration |
|
|
1703 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
|
|
1704 | |
|
|
1705 | # Event integration |
|
|
1706 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1707 | poll => 'r', |
|
|
1708 | cb => \&IO::AIO::poll_cb); |
|
|
1709 | |
|
|
1710 | # Glib/Gtk2 integration |
|
|
1711 | add_watch Glib::IO IO::AIO::poll_fileno, |
|
|
1712 | in => sub { IO::AIO::poll_cb; 1 }; |
|
|
1713 | |
|
|
1714 | # Tk integration |
|
|
1715 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
|
|
1716 | readable => \&IO::AIO::poll_cb); |
|
|
1717 | |
|
|
1718 | # Danga::Socket integration |
|
|
1719 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
|
|
1720 | \&IO::AIO::poll_cb); |
|
|
1721 | |
|
|
1722 | FORK BEHAVIOUR |
|
|
1723 | Usage of pthreads in a program changes the semantics of fork |
|
|
1724 | considerably. Specifically, only async-safe functions can be called |
|
|
1725 | after fork. Perl doesn't know about this, so in general, you cannot call |
|
|
1726 | fork with defined behaviour in perl if pthreads are involved. IO::AIO |
|
|
1727 | uses pthreads, so this applies, but many other extensions and (for |
|
|
1728 | inexplicable reasons) perl itself often is linked against pthreads, so |
|
|
1729 | this limitation applies to quite a lot of perls. |
|
|
1730 | |
|
|
1731 | This module no longer tries to fight your OS, or POSIX. That means |
|
|
1732 | IO::AIO only works in the process that loaded it. Forking is fully |
|
|
1733 | supported, but using IO::AIO in the child is not. |
|
|
1734 | |
|
|
1735 | You might get around by not *using* IO::AIO before (or after) forking. |
|
|
1736 | You could also try to call the IO::AIO::reinit function in the child: |
|
|
1737 | |
|
|
1738 | IO::AIO::reinit |
|
|
1739 | Abandons all current requests and I/O threads and simply |
|
|
1740 | reinitialises all data structures. This is not an operation |
|
|
1741 | supported by any standards, but happens to work on GNU/Linux and |
|
|
1742 | some newer BSD systems. |
|
|
1743 | |
|
|
1744 | The only reasonable use for this function is to call it after |
|
|
1745 | forking, if "IO::AIO" was used in the parent. Calling it while |
|
|
1746 | IO::AIO is active in the process will result in undefined behaviour. |
|
|
1747 | Calling it at any time will also result in any undefined (by POSIX) |
|
|
1748 | behaviour. |
|
|
1749 | |
|
|
1750 | MEMORY USAGE |
|
|
1751 | Per-request usage: |
|
|
1752 | |
|
|
1753 | Each aio request uses - depending on your architecture - around 100-200 |
|
|
1754 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
|
|
1755 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
|
|
1756 | scalars and other data passed into aio requests will also be locked and |
|
|
1757 | will consume memory till the request has entered the done state. |
|
|
1758 | |
|
|
1759 | This is not awfully much, so queuing lots of requests is not usually a |
|
|
1760 | problem. |
|
|
1761 | |
|
|
1762 | Per-thread usage: |
|
|
1763 | |
|
|
1764 | In the execution phase, some aio requests require more memory for |
|
|
1765 | temporary buffers, and each thread requires a stack and other data |
|
|
1766 | structures (usually around 16k-128k, depending on the OS). |
|
|
1767 | |
|
|
1768 | KNOWN BUGS |
|
|
1769 | Known bugs will be fixed in the next release. |
227 | |
1770 | |
228 | SEE ALSO |
1771 | SEE ALSO |
229 | Coro, Linux::AIO. |
1772 | AnyEvent::AIO for easy integration into event loops, Coro::AIO for a |
|
|
1773 | more natural syntax. |
230 | |
1774 | |
231 | AUTHOR |
1775 | AUTHOR |
232 | Marc Lehmann <schmorp@schmorp.de> |
1776 | Marc Lehmann <schmorp@schmorp.de> |
233 | http://home.schmorp.de/ |
1777 | http://home.schmorp.de/ |
234 | |
1778 | |