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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 | # AnyEvent |
19 | # version 2+ has request and group objects |
19 | open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; |
20 | use IO::AIO 2; |
20 | my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); |
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21 | |
21 | |
22 | # Event |
22 | aioreq_pri 4; # give next request a very high priority |
23 | Event->io (fd => IO::AIO::poll_fileno, |
23 | my $req = aio_unlink "/tmp/file", sub { }; |
24 | poll => 'r', |
24 | $req->cancel; # cancel request if still in queue |
25 | cb => \&IO::AIO::poll_cb); |
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26 | |
25 | |
27 | # Glib/Gtk2 |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
28 | add_watch Glib::IO IO::AIO::poll_fileno, |
27 | add $grp aio_stat "..." for ...; |
29 | in => sub { IO::AIO::poll_cb; 1 }; |
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30 | |
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31 | # Tk |
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32 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
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33 | readable => \&IO::AIO::poll_cb); |
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34 | |
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35 | # Danga::Socket |
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36 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
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37 | \&IO::AIO::poll_cb); |
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38 | |
28 | |
39 | DESCRIPTION |
29 | DESCRIPTION |
40 | This module implements asynchronous I/O using whatever means your |
30 | This module implements asynchronous I/O using whatever means your |
41 | 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>). |
42 | |
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 | |
43 | 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 |
44 | 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 |
45 | 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 |
46 | 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 |
47 | native aio functions available on many operating systems. However, they |
54 | functions available on many operating systems. However, they are often |
48 | 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 |
49 | currently, for example), and they would only support aio_read and |
56 | files currently, for example), and they would only support aio_read and |
50 | aio_write, so the remaining functionality would have to be implemented |
57 | aio_write, so the remaining functionality would have to be implemented |
51 | using threads anyway. |
58 | using threads anyway. |
52 | |
59 | |
53 | 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, |
54 | is currently not reentrant, so use appropriate locking yourself, always |
61 | it is currently not reentrant in any way, so use appropriate locking |
55 | call "poll_cb" from within the same thread, or never call "poll_cb" (or |
62 | yourself, always call "poll_cb" from within the same thread, or never |
56 | other "aio_" functions) recursively. |
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 Fcntl; |
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70 | use EV; |
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71 | use IO::AIO; |
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72 | |
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73 | # register the IO::AIO callback with EV |
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74 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
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75 | |
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76 | # queue the request to open /etc/passwd |
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77 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
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78 | my $fh = shift |
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79 | or die "error while opening: $!"; |
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80 | |
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81 | # stat'ing filehandles is generally non-blocking |
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82 | my $size = -s $fh; |
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83 | |
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84 | # queue a request to read the file |
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85 | my $contents; |
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86 | aio_read $fh, 0, $size, $contents, 0, sub { |
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87 | $_[0] == $size |
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88 | or die "short read: $!"; |
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89 | |
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90 | close $fh; |
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91 | |
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92 | # file contents now in $contents |
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93 | print $contents; |
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94 | |
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95 | # exit event loop and program |
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96 | EV::unloop; |
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97 | }; |
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98 | }; |
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99 | |
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100 | # possibly queue up other requests, or open GUI windows, |
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101 | # check for sockets etc. etc. |
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102 | |
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103 | # process events as long as there are some: |
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104 | EV::loop; |
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105 | |
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106 | REQUEST ANATOMY AND LIFETIME |
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107 | Every "aio_*" function creates a request. which is a C data structure |
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108 | not directly visible to Perl. |
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109 | |
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110 | If called in non-void context, every request function returns a Perl |
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111 | object representing the request. In void context, nothing is returned, |
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112 | which saves a bit of memory. |
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113 | |
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114 | The perl object is a fairly standard ref-to-hash object. The hash |
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115 | contents are not used by IO::AIO so you are free to store anything you |
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116 | like in it. |
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117 | |
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118 | During their existance, aio requests travel through the following |
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119 | states, in order: |
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120 | |
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121 | ready |
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122 | Immediately after a request is created it is put into the ready |
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123 | state, waiting for a thread to execute it. |
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124 | |
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125 | execute |
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126 | A thread has accepted the request for processing and is currently |
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127 | executing it (e.g. blocking in read). |
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128 | |
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129 | pending |
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130 | The request has been executed and is waiting for result processing. |
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131 | |
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132 | While request submission and execution is fully asynchronous, result |
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133 | processing is not and relies on the perl interpreter calling |
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134 | "poll_cb" (or another function with the same effect). |
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135 | |
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136 | result |
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137 | The request results are processed synchronously by "poll_cb". |
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138 | |
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139 | The "poll_cb" function will process all outstanding aio requests by |
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140 | calling their callbacks, freeing memory associated with them and |
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141 | managing any groups they are contained in. |
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142 | |
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143 | done |
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144 | Request has reached the end of its lifetime and holds no resources |
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145 | anymore (except possibly for the Perl object, but its connection to |
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146 | the actual aio request is severed and calling its methods will |
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147 | either do nothing or result in a runtime error). |
57 | |
148 | |
58 | FUNCTIONS |
149 | FUNCTIONS |
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150 | QUICK OVERVIEW |
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151 | This section simply lists the prototypes of the most important functions |
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152 | for quick reference. See the following sections for function-by-function |
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153 | documentation. |
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154 | |
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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_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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158 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
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159 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
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160 | aio_readahead $fh,$offset,$length, $callback->($retval) |
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161 | aio_stat $fh_or_path, $callback->($status) |
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162 | aio_lstat $fh, $callback->($status) |
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163 | aio_statvfs $fh_or_path, $callback->($statvfs) |
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164 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
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165 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
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166 | aio_truncate $fh_or_path, $offset, $callback->($status) |
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167 | aio_chmod $fh_or_path, $mode, $callback->($status) |
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168 | aio_unlink $pathname, $callback->($status) |
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169 | aio_mknod $path, $mode, $dev, $callback->($status) |
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170 | aio_link $srcpath, $dstpath, $callback->($status) |
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171 | aio_symlink $srcpath, $dstpath, $callback->($status) |
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172 | aio_readlink $path, $callback->($link) |
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173 | aio_rename $srcpath, $dstpath, $callback->($status) |
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174 | aio_mkdir $pathname, $mode, $callback->($status) |
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175 | aio_rmdir $pathname, $callback->($status) |
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176 | aio_readdir $pathname, $callback->($entries) |
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177 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
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178 | IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST |
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179 | IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN |
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180 | aio_load $path, $data, $callback->($status) |
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181 | aio_copy $srcpath, $dstpath, $callback->($status) |
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182 | aio_move $srcpath, $dstpath, $callback->($status) |
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183 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
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184 | aio_rmtree $path, $callback->($status) |
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185 | aio_sync $callback->($status) |
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186 | aio_fsync $fh, $callback->($status) |
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187 | aio_fdatasync $fh, $callback->($status) |
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188 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
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189 | aio_pathsync $path, $callback->($status) |
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190 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
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191 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
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192 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
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193 | aio_mlockall $flags, $callback->($status) |
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194 | aio_group $callback->(...) |
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195 | aio_nop $callback->() |
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196 | |
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197 | $prev_pri = aioreq_pri [$pri] |
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198 | aioreq_nice $pri_adjust |
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199 | |
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200 | IO::AIO::poll_wait |
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201 | IO::AIO::poll_cb |
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202 | IO::AIO::poll |
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203 | IO::AIO::flush |
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204 | IO::AIO::max_poll_reqs $nreqs |
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205 | IO::AIO::max_poll_time $seconds |
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206 | IO::AIO::min_parallel $nthreads |
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207 | IO::AIO::max_parallel $nthreads |
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208 | IO::AIO::max_idle $nthreads |
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209 | IO::AIO::idle_timeout $seconds |
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210 | IO::AIO::max_outstanding $maxreqs |
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211 | IO::AIO::nreqs |
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212 | IO::AIO::nready |
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213 | IO::AIO::npending |
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214 | |
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215 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
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216 | IO::AIO::fadvise $fh, $offset, $len, $advice |
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217 | IO::AIO::madvise $scalar, $offset, $length, $advice |
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218 | IO::AIO::mprotect $scalar, $offset, $length, $protect |
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219 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
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220 | IO::AIO::munlockall |
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221 | |
59 | AIO FUNCTIONS |
222 | AIO REQUEST FUNCTIONS |
60 | All the "aio_*" calls are more or less thin wrappers around the syscall |
223 | All the "aio_*" calls are more or less thin wrappers around the syscall |
61 | with the same name (sans "aio_"). The arguments are similar or |
224 | with the same name (sans "aio_"). The arguments are similar or |
62 | identical, and they all accept an additional (and optional) $callback |
225 | identical, and they all accept an additional (and optional) $callback |
63 | argument which must be a code reference. This code reference will get |
226 | argument which must be a code reference. This code reference will get |
64 | called with the syscall return code (e.g. most syscalls return -1 on |
227 | called with the syscall return code (e.g. most syscalls return -1 on |
65 | error, unlike perl, which usually delivers "false") as it's sole |
228 | error, unlike perl, which usually delivers "false") as its sole argument |
66 | argument when the given syscall has been executed asynchronously. |
229 | after the given syscall has been executed asynchronously. |
67 | |
230 | |
68 | All functions expecting a filehandle keep a copy of the filehandle |
231 | All functions expecting a filehandle keep a copy of the filehandle |
69 | internally until the request has finished. |
232 | internally until the request has finished. |
70 | |
233 | |
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234 | All functions return request objects of type IO::AIO::REQ that allow |
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235 | further manipulation of those requests while they are in-flight. |
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236 | |
71 | The pathnames you pass to these routines *must* be absolute and encoded |
237 | The pathnames you pass to these routines *must* be absolute and encoded |
72 | in byte form. The reason for the former is that at the time the request |
238 | as octets. The reason for the former is that at the time the request is |
73 | is being executed, the current working directory could have changed. |
239 | being executed, the current working directory could have changed. |
74 | Alternatively, you can make sure that you never change the current |
240 | Alternatively, you can make sure that you never change the current |
75 | working directory. |
241 | working directory anywhere in the program and then use relative paths. |
76 | |
242 | |
77 | To encode pathnames to byte form, either make sure you either: a) always |
243 | To encode pathnames as octets, either make sure you either: a) always |
78 | pass in filenames you got from outside (command line, readdir etc.), b) |
244 | pass in filenames you got from outside (command line, readdir etc.) |
79 | are ASCII or ISO 8859-1, c) use the Encode module and encode your |
245 | without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module |
80 | pathnames to the locale (or other) encoding in effect in the user |
246 | and encode your pathnames to the locale (or other) encoding in effect in |
81 | environment, d) use Glib::filename_from_unicode on unicode filenames or |
247 | the user environment, d) use Glib::filename_from_unicode on unicode |
82 | e) use something else. |
248 | filenames or e) use something else to ensure your scalar has the correct |
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249 | contents. |
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250 | |
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251 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
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252 | handles correctly whether it is set or not. |
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253 | |
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254 | $prev_pri = aioreq_pri [$pri] |
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255 | Returns the priority value that would be used for the next request |
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256 | and, if $pri is given, sets the priority for the next aio request. |
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257 | |
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258 | The default priority is 0, the minimum and maximum priorities are -4 |
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259 | and 4, respectively. Requests with higher priority will be serviced |
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260 | first. |
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261 | |
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262 | The priority will be reset to 0 after each call to one of the |
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263 | "aio_*" functions. |
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264 | |
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265 | Example: open a file with low priority, then read something from it |
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266 | with higher priority so the read request is serviced before other |
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267 | low priority open requests (potentially spamming the cache): |
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268 | |
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269 | aioreq_pri -3; |
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270 | aio_open ..., sub { |
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271 | return unless $_[0]; |
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272 | |
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273 | aioreq_pri -2; |
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274 | aio_read $_[0], ..., sub { |
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275 | ... |
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276 | }; |
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277 | }; |
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278 | |
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279 | aioreq_nice $pri_adjust |
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280 | Similar to "aioreq_pri", but subtracts the given value from the |
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281 | current priority, so the effect is cumulative. |
83 | |
282 | |
84 | aio_open $pathname, $flags, $mode, $callback->($fh) |
283 | aio_open $pathname, $flags, $mode, $callback->($fh) |
85 | Asynchronously open or create a file and call the callback with a |
284 | Asynchronously open or create a file and call the callback with a |
86 | newly created filehandle for the file. |
285 | newly created filehandle for the file. |
87 | |
286 | |
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92 | They are the same as used by "sysopen". |
291 | They are the same as used by "sysopen". |
93 | |
292 | |
94 | Likewise, $mode specifies the mode of the newly created file, if it |
293 | Likewise, $mode specifies the mode of the newly created file, if it |
95 | didn't exist and "O_CREAT" has been given, just like perl's |
294 | didn't exist and "O_CREAT" has been given, just like perl's |
96 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
295 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
97 | create new files, and 0666 or 0777 if you do). |
296 | create new files, and 0666 or 0777 if you do). Note that the $mode |
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297 | will be modified by the umask in effect then the request is being |
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298 | executed, so better never change the umask. |
98 | |
299 | |
99 | Example: |
300 | Example: |
100 | |
301 | |
101 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
302 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
102 | if ($_[0]) { |
303 | if ($_[0]) { |
103 | print "open successful, fh is $_[0]\n"; |
304 | print "open successful, fh is $_[0]\n"; |
104 | ... |
305 | ... |
105 | } else { |
306 | } else { |
106 | die "open failed: $!\n"; |
307 | die "open failed: $!\n"; |
107 | } |
308 | } |
108 | }; |
309 | }; |
109 | |
310 | |
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311 | In addition to all the common open modes/flags ("O_RDONLY", |
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312 | "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and |
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313 | "O_APPEND"), the following POSIX and non-POSIX constants are |
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314 | available (missing ones on your system are, as usual, 0): |
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315 | |
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316 | "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", |
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317 | "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", |
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318 | "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". |
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319 | |
110 | aio_close $fh, $callback->($status) |
320 | aio_close $fh, $callback->($status) |
111 | Asynchronously close a file and call the callback with the result |
321 | Asynchronously close a file and call the callback with the result |
112 | code. *WARNING:* although accepted, you should not pass in a perl |
322 | code. |
113 | filehandle here, as perl will likely close the file descriptor |
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114 | another time when the filehandle is destroyed. Normally, you can |
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115 | safely call perls "close" or just let filehandles go out of scope. |
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116 | |
323 | |
117 | This is supposed to be a bug in the API, so that might change. It's |
324 | Unfortunately, you can't do this to perl. Perl *insists* very |
118 | therefore best to avoid this function. |
325 | strongly on closing the file descriptor associated with the |
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326 | filehandle itself. |
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327 | |
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328 | Therefore, "aio_close" will not close the filehandle - instead it |
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329 | will use dup2 to overwrite the file descriptor with the write-end of |
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330 | a pipe (the pipe fd will be created on demand and will be cached). |
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331 | |
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332 | Or in other words: the file descriptor will be closed, but it will |
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333 | not be free for reuse until the perl filehandle is closed. |
119 | |
334 | |
120 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
335 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
121 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
336 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
122 | Reads or writes "length" bytes from the specified "fh" and "offset" |
337 | Reads or writes $length bytes from or to the specified $fh and |
123 | into the scalar given by "data" and offset "dataoffset" and calls |
338 | $offset into the scalar given by $data and offset $dataoffset and |
124 | the callback without the actual number of bytes read (or -1 on |
339 | calls the callback without the actual number of bytes read (or -1 on |
125 | error, just like the syscall). |
340 | error, just like the syscall). |
126 | |
341 | |
|
|
342 | "aio_read" will, like "sysread", shrink or grow the $data scalar to |
|
|
343 | offset plus the actual number of bytes read. |
|
|
344 | |
|
|
345 | If $offset is undefined, then the current file descriptor offset |
|
|
346 | will be used (and updated), otherwise the file descriptor offset |
|
|
347 | will not be changed by these calls. |
|
|
348 | |
|
|
349 | If $length is undefined in "aio_write", use the remaining length of |
|
|
350 | $data. |
|
|
351 | |
|
|
352 | If $dataoffset is less than zero, it will be counted from the end of |
|
|
353 | $data. |
|
|
354 | |
127 | The $data scalar *MUST NOT* be modified in any way while the request |
355 | The $data scalar *MUST NOT* be modified in any way while the request |
128 | is outstanding. Modifying it can result in segfaults or WW3 (if the |
356 | is outstanding. Modifying it can result in segfaults or World War |
129 | necessary/optional hardware is installed). |
357 | III (if the necessary/optional hardware is installed). |
130 | |
358 | |
131 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
359 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
132 | offset 0 within the scalar: |
360 | offset 0 within the scalar: |
133 | |
361 | |
134 | aio_read $fh, 7, 15, $buffer, 0, sub { |
362 | aio_read $fh, 7, 15, $buffer, 0, sub { |
… | |
… | |
139 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
367 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
140 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
368 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
141 | reading at byte offset $in_offset, and starts writing at the current |
369 | reading at byte offset $in_offset, and starts writing at the current |
142 | file offset of $out_fh. Because of that, it is not safe to issue |
370 | file offset of $out_fh. Because of that, it is not safe to issue |
143 | more than one "aio_sendfile" per $out_fh, as they will interfere |
371 | more than one "aio_sendfile" per $out_fh, as they will interfere |
144 | with each other. |
372 | with each other. The same $in_fh works fine though, as this function |
|
|
373 | does not move or use the file offset of $in_fh. |
145 | |
374 | |
|
|
375 | Please note that "aio_sendfile" can read more bytes from $in_fh than |
|
|
376 | are written, and there is no way to find out how many more bytes |
|
|
377 | have been read from "aio_sendfile" alone, as "aio_sendfile" only |
|
|
378 | provides the number of bytes written to $out_fh. Only if the result |
|
|
379 | value equals $length one can assume that $length bytes have been |
|
|
380 | read. |
|
|
381 | |
|
|
382 | Unlike with other "aio_" functions, it makes a lot of sense to use |
|
|
383 | "aio_sendfile" on non-blocking sockets, as long as one end |
|
|
384 | (typically the $in_fh) is a file - the file I/O will then be |
|
|
385 | asynchronous, while the socket I/O will be non-blocking. Note, |
|
|
386 | however, that you can run into a trap where "aio_sendfile" reads |
|
|
387 | some data with readahead, then fails to write all data, and when the |
|
|
388 | socket is ready the next time, the data in the cache is already |
|
|
389 | lost, forcing "aio_sendfile" to again hit the disk. Explicit |
|
|
390 | "aio_read" + "aio_write" let's you better control resource usage. |
|
|
391 | |
146 | This call tries to make use of a native "sendfile" syscall to |
392 | This call tries to make use of a native "sendfile"-like syscall to |
147 | provide zero-copy operation. For this to work, $out_fh should refer |
393 | provide zero-copy operation. For this to work, $out_fh should refer |
148 | to a socket, and $in_fh should refer to mmap'able file. |
394 | to a socket, and $in_fh should refer to an mmap'able file. |
149 | |
395 | |
150 | If the native sendfile call fails or is not implemented, it will be |
396 | If a native sendfile cannot be found or it fails with "ENOSYS", |
151 | emulated, so you can call "aio_sendfile" on any type of filehandle |
397 | "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or |
152 | regardless of the limitations of the operating system. |
398 | "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on |
|
|
399 | any type of filehandle regardless of the limitations of the |
|
|
400 | operating system. |
153 | |
401 | |
154 | Please note, however, that "aio_sendfile" can read more bytes from |
402 | As native sendfile syscalls (as practically any non-POSIX interface |
155 | $in_fh than are written, and there is no way to find out how many |
403 | hacked together in a hurry to improve benchmark numbers) tend to be |
156 | bytes have been read from "aio_sendfile" alone, as "aio_sendfile" |
404 | rather buggy on many systems, this implementation tries to work |
157 | only provides the number of bytes written to $out_fh. Only if the |
405 | around some known bugs in Linux and FreeBSD kernels (probably |
158 | result value equals $length one can assume that $length bytes have |
406 | others, too), but that might fail, so you really really should check |
159 | been read. |
407 | the return value of "aio_sendfile" - fewre bytes than expected might |
|
|
408 | have been transferred. |
160 | |
409 | |
161 | aio_readahead $fh,$offset,$length, $callback->($retval) |
410 | aio_readahead $fh,$offset,$length, $callback->($retval) |
162 | "aio_readahead" populates the page cache with data from a file so |
411 | "aio_readahead" populates the page cache with data from a file so |
163 | that subsequent reads from that file will not block on disk I/O. The |
412 | that subsequent reads from that file will not block on disk I/O. The |
164 | $offset argument specifies the starting point from which data is to |
413 | $offset argument specifies the starting point from which data is to |
… | |
… | |
185 | Currently, the stats are always 64-bit-stats, i.e. instead of |
434 | Currently, the stats are always 64-bit-stats, i.e. instead of |
186 | returning an error when stat'ing a large file, the results will be |
435 | returning an error when stat'ing a large file, the results will be |
187 | silently truncated unless perl itself is compiled with large file |
436 | silently truncated unless perl itself is compiled with large file |
188 | support. |
437 | support. |
189 | |
438 | |
|
|
439 | To help interpret the mode and dev/rdev stat values, IO::AIO offers |
|
|
440 | the following constants and functions (if not implemented, the |
|
|
441 | constants will be 0 and the functions will either "croak" or fall |
|
|
442 | back on traditional behaviour). |
|
|
443 | |
|
|
444 | "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", |
|
|
445 | "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", |
|
|
446 | "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". |
|
|
447 | |
190 | Example: Print the length of /etc/passwd: |
448 | Example: Print the length of /etc/passwd: |
191 | |
449 | |
192 | aio_stat "/etc/passwd", sub { |
450 | aio_stat "/etc/passwd", sub { |
193 | $_[0] and die "stat failed: $!"; |
451 | $_[0] and die "stat failed: $!"; |
194 | print "size is ", -s _, "\n"; |
452 | print "size is ", -s _, "\n"; |
195 | }; |
453 | }; |
196 | |
454 | |
|
|
455 | aio_statvfs $fh_or_path, $callback->($statvfs) |
|
|
456 | Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on |
|
|
457 | whether a file handle or path was passed. |
|
|
458 | |
|
|
459 | On success, the callback is passed a hash reference with the |
|
|
460 | following members: "bsize", "frsize", "blocks", "bfree", "bavail", |
|
|
461 | "files", "ffree", "favail", "fsid", "flag" and "namemax". On |
|
|
462 | failure, "undef" is passed. |
|
|
463 | |
|
|
464 | The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY" |
|
|
465 | and "ST_NOSUID". |
|
|
466 | |
|
|
467 | The following non-POSIX IO::AIO::ST_* flag masks are defined to |
|
|
468 | their correct value when available, or to 0 on systems that do not |
|
|
469 | support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS", |
|
|
470 | "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE", |
|
|
471 | "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME". |
|
|
472 | |
|
|
473 | Example: stat "/wd" and dump out the data if successful. |
|
|
474 | |
|
|
475 | aio_statvfs "/wd", sub { |
|
|
476 | my $f = $_[0] |
|
|
477 | or die "statvfs: $!"; |
|
|
478 | |
|
|
479 | use Data::Dumper; |
|
|
480 | say Dumper $f; |
|
|
481 | }; |
|
|
482 | |
|
|
483 | # result: |
|
|
484 | { |
|
|
485 | bsize => 1024, |
|
|
486 | bfree => 4333064312, |
|
|
487 | blocks => 10253828096, |
|
|
488 | files => 2050765568, |
|
|
489 | flag => 4096, |
|
|
490 | favail => 2042092649, |
|
|
491 | bavail => 4333064312, |
|
|
492 | ffree => 2042092649, |
|
|
493 | namemax => 255, |
|
|
494 | frsize => 1024, |
|
|
495 | fsid => 1810 |
|
|
496 | } |
|
|
497 | |
|
|
498 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
|
|
499 | Works like perl's "utime" function (including the special case of |
|
|
500 | $atime and $mtime being undef). Fractional times are supported if |
|
|
501 | the underlying syscalls support them. |
|
|
502 | |
|
|
503 | When called with a pathname, uses utimes(2) if available, otherwise |
|
|
504 | utime(2). If called on a file descriptor, uses futimes(2) if |
|
|
505 | available, otherwise returns ENOSYS, so this is not portable. |
|
|
506 | |
|
|
507 | Examples: |
|
|
508 | |
|
|
509 | # set atime and mtime to current time (basically touch(1)): |
|
|
510 | aio_utime "path", undef, undef; |
|
|
511 | # set atime to current time and mtime to beginning of the epoch: |
|
|
512 | aio_utime "path", time, undef; # undef==0 |
|
|
513 | |
|
|
514 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
|
|
515 | Works like perl's "chown" function, except that "undef" for either |
|
|
516 | $uid or $gid is being interpreted as "do not change" (but -1 can |
|
|
517 | also be used). |
|
|
518 | |
|
|
519 | Examples: |
|
|
520 | |
|
|
521 | # same as "chown root path" in the shell: |
|
|
522 | aio_chown "path", 0, -1; |
|
|
523 | # same as above: |
|
|
524 | aio_chown "path", 0, undef; |
|
|
525 | |
|
|
526 | aio_truncate $fh_or_path, $offset, $callback->($status) |
|
|
527 | Works like truncate(2) or ftruncate(2). |
|
|
528 | |
|
|
529 | aio_chmod $fh_or_path, $mode, $callback->($status) |
|
|
530 | Works like perl's "chmod" function. |
|
|
531 | |
197 | aio_unlink $pathname, $callback->($status) |
532 | aio_unlink $pathname, $callback->($status) |
198 | Asynchronously unlink (delete) a file and call the callback with the |
533 | Asynchronously unlink (delete) a file and call the callback with the |
199 | result code. |
534 | result code. |
|
|
535 | |
|
|
536 | aio_mknod $path, $mode, $dev, $callback->($status) |
|
|
537 | [EXPERIMENTAL] |
|
|
538 | |
|
|
539 | Asynchronously create a device node (or fifo). See mknod(2). |
|
|
540 | |
|
|
541 | The only (POSIX-) portable way of calling this function is: |
|
|
542 | |
|
|
543 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
|
|
544 | |
|
|
545 | See "aio_stat" for info about some potentially helpful extra |
|
|
546 | constants and functions. |
|
|
547 | |
|
|
548 | aio_link $srcpath, $dstpath, $callback->($status) |
|
|
549 | Asynchronously create a new link to the existing object at $srcpath |
|
|
550 | at the path $dstpath and call the callback with the result code. |
|
|
551 | |
|
|
552 | aio_symlink $srcpath, $dstpath, $callback->($status) |
|
|
553 | Asynchronously create a new symbolic link to the existing object at |
|
|
554 | $srcpath at the path $dstpath and call the callback with the result |
|
|
555 | code. |
|
|
556 | |
|
|
557 | aio_readlink $path, $callback->($link) |
|
|
558 | Asynchronously read the symlink specified by $path and pass it to |
|
|
559 | the callback. If an error occurs, nothing or undef gets passed to |
|
|
560 | the callback. |
|
|
561 | |
|
|
562 | aio_rename $srcpath, $dstpath, $callback->($status) |
|
|
563 | Asynchronously rename the object at $srcpath to $dstpath, just as |
|
|
564 | rename(2) and call the callback with the result code. |
|
|
565 | |
|
|
566 | aio_mkdir $pathname, $mode, $callback->($status) |
|
|
567 | Asynchronously mkdir (create) a directory and call the callback with |
|
|
568 | the result code. $mode will be modified by the umask at the time the |
|
|
569 | request is executed, so do not change your umask. |
200 | |
570 | |
201 | aio_rmdir $pathname, $callback->($status) |
571 | aio_rmdir $pathname, $callback->($status) |
202 | Asynchronously rmdir (delete) a directory and call the callback with |
572 | Asynchronously rmdir (delete) a directory and call the callback with |
203 | the result code. |
573 | the result code. |
204 | |
574 | |
205 | aio_readdir $pathname, $callback->($entries) |
575 | aio_readdir $pathname, $callback->($entries) |
206 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
576 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
207 | entire directory (i.e. opendir + readdir + closedir). The entries |
577 | entire directory (i.e. opendir + readdir + closedir). The entries |
208 | will not be sorted, and will NOT include the "." and ".." entries. |
578 | will not be sorted, and will NOT include the "." and ".." entries. |
209 | |
579 | |
210 | The callback a single argument which is either "undef" or an |
580 | The callback is passed a single argument which is either "undef" or |
211 | array-ref with the filenames. |
581 | an array-ref with the filenames. |
|
|
582 | |
|
|
583 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
|
|
584 | Quite similar to "aio_readdir", but the $flags argument allows to |
|
|
585 | tune behaviour and output format. In case of an error, $entries will |
|
|
586 | be "undef". |
|
|
587 | |
|
|
588 | The flags are a combination of the following constants, ORed |
|
|
589 | together (the flags will also be passed to the callback, possibly |
|
|
590 | modified): |
|
|
591 | |
|
|
592 | IO::AIO::READDIR_DENTS |
|
|
593 | When this flag is off, then the callback gets an arrayref |
|
|
594 | consisting of names only (as with "aio_readdir"), otherwise it |
|
|
595 | gets an arrayref with "[$name, $type, $inode]" arrayrefs, each |
|
|
596 | describing a single directory entry in more detail. |
|
|
597 | |
|
|
598 | $name is the name of the entry. |
|
|
599 | |
|
|
600 | $type is one of the "IO::AIO::DT_xxx" constants: |
|
|
601 | |
|
|
602 | "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", |
|
|
603 | "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", |
|
|
604 | "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". |
|
|
605 | |
|
|
606 | "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If |
|
|
607 | you need to know, you have to run stat yourself. Also, for speed |
|
|
608 | reasons, the $type scalars are read-only: you can not modify |
|
|
609 | them. |
|
|
610 | |
|
|
611 | $inode is the inode number (which might not be exact on systems |
|
|
612 | with 64 bit inode numbers and 32 bit perls). This field has |
|
|
613 | unspecified content on systems that do not deliver the inode |
|
|
614 | information. |
|
|
615 | |
|
|
616 | IO::AIO::READDIR_DIRS_FIRST |
|
|
617 | When this flag is set, then the names will be returned in an |
|
|
618 | order where likely directories come first, in optimal stat |
|
|
619 | order. This is useful when you need to quickly find directories, |
|
|
620 | or you want to find all directories while avoiding to stat() |
|
|
621 | each entry. |
|
|
622 | |
|
|
623 | If the system returns type information in readdir, then this is |
|
|
624 | used to find directories directly. Otherwise, likely directories |
|
|
625 | are names beginning with ".", or otherwise names with no dots, |
|
|
626 | of which names with short names are tried first. |
|
|
627 | |
|
|
628 | IO::AIO::READDIR_STAT_ORDER |
|
|
629 | When this flag is set, then the names will be returned in an |
|
|
630 | order suitable for stat()'ing each one. That is, when you plan |
|
|
631 | to stat() all files in the given directory, then the returned |
|
|
632 | order will likely be fastest. |
|
|
633 | |
|
|
634 | If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are |
|
|
635 | specified, then the likely dirs come first, resulting in a less |
|
|
636 | optimal stat order. |
|
|
637 | |
|
|
638 | IO::AIO::READDIR_FOUND_UNKNOWN |
|
|
639 | This flag should not be set when calling "aio_readdirx". |
|
|
640 | Instead, it is being set by "aio_readdirx", when any of the |
|
|
641 | $type's found were "IO::AIO::DT_UNKNOWN". The absense of this |
|
|
642 | flag therefore indicates that all $type's are known, which can |
|
|
643 | be used to speed up some algorithms. |
|
|
644 | |
|
|
645 | aio_load $path, $data, $callback->($status) |
|
|
646 | This is a composite request that tries to fully load the given file |
|
|
647 | into memory. Status is the same as with aio_read. |
|
|
648 | |
|
|
649 | aio_copy $srcpath, $dstpath, $callback->($status) |
|
|
650 | Try to copy the *file* (directories not supported as either source |
|
|
651 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
652 | a status of 0 (ok) or -1 (error, see $!). |
|
|
653 | |
|
|
654 | This is a composite request that creates the destination file with |
|
|
655 | mode 0200 and copies the contents of the source file into it using |
|
|
656 | "aio_sendfile", followed by restoring atime, mtime, access mode and |
|
|
657 | uid/gid, in that order. |
|
|
658 | |
|
|
659 | If an error occurs, the partial destination file will be unlinked, |
|
|
660 | if possible, except when setting atime, mtime, access mode and |
|
|
661 | uid/gid, where errors are being ignored. |
|
|
662 | |
|
|
663 | aio_move $srcpath, $dstpath, $callback->($status) |
|
|
664 | Try to move the *file* (directories not supported as either source |
|
|
665 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
666 | a status of 0 (ok) or -1 (error, see $!). |
|
|
667 | |
|
|
668 | This is a composite request that tries to rename(2) the file first; |
|
|
669 | if rename fails with "EXDEV", it copies the file with "aio_copy" |
|
|
670 | and, if that is successful, unlinks the $srcpath. |
212 | |
671 | |
213 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
672 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
214 | Scans a directory (similar to "aio_readdir") and tries to separate |
673 | Scans a directory (similar to "aio_readdir") but additionally tries |
215 | the entries of directory $path into two sets of names, ones you can |
674 | to efficiently separate the entries of directory $path into two sets |
216 | recurse into (directories), and ones you cannot recurse into |
675 | of names, directories you can recurse into (directories), and ones |
217 | (everything else). |
676 | you cannot recurse into (everything else, including symlinks to |
|
|
677 | directories). |
218 | |
678 | |
219 | "aio_scandir" is a composite request that consists of many |
679 | "aio_scandir" is a composite request that creates of many sub |
220 | aio-primitives. $maxreq specifies the maximum number of outstanding |
680 | requests_ $maxreq specifies the maximum number of outstanding aio |
221 | aio requests that this function generates. If it is "<= 0", then a |
681 | requests that this function generates. If it is "<= 0", then a |
222 | suitable default will be chosen (currently 8). |
682 | suitable default will be chosen (currently 4). |
223 | |
683 | |
224 | On error, the callback is called without arguments, otherwise it |
684 | On error, the callback is called without arguments, otherwise it |
225 | receives two array-refs with path-relative entry names. |
685 | receives two array-refs with path-relative entry names. |
226 | |
686 | |
227 | Example: |
687 | Example: |
… | |
… | |
235 | Implementation notes. |
695 | Implementation notes. |
236 | |
696 | |
237 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
697 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
238 | can. |
698 | can. |
239 | |
699 | |
|
|
700 | If readdir returns file type information, then this is used directly |
|
|
701 | to find directories. |
|
|
702 | |
240 | After reading the directory, the modification time, size etc. of the |
703 | Otherwise, after reading the directory, the modification time, size |
241 | directory before and after the readdir is checked, and if they |
704 | etc. of the directory before and after the readdir is checked, and |
242 | match, the link count will be used to decide how many entries are |
705 | if they match (and isn't the current time), the link count will be |
243 | directories (if >= 2). Otherwise, no knowledge of the number of |
706 | used to decide how many entries are directories (if >= 2). |
244 | subdirectories will be assumed. |
707 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
708 | assumed. |
245 | |
709 | |
246 | Then entires will be sorted into likely directories (everything |
710 | Then entries will be sorted into likely directories a non-initial |
247 | without a non-initial dot) and likely non-directories (everything |
711 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
248 | else). Then every entry + "/." will be "stat"'ed, likely directories |
712 | every entry plus an appended "/." will be "stat"'ed, likely |
249 | first. This is often faster because filesystems might detect the |
713 | directories first, in order of their inode numbers. If that |
|
|
714 | succeeds, it assumes that the entry is a directory or a symlink to |
|
|
715 | directory (which will be checked seperately). This is often faster |
|
|
716 | than stat'ing the entry itself because filesystems might detect the |
250 | type of the entry without reading the inode data (e.g. ext2s |
717 | type of the entry without reading the inode data (e.g. ext2fs |
251 | filetype feature). If that succeeds, it assumes that the entry is a |
718 | filetype feature), even on systems that cannot return the filetype |
252 | directory or a symlink to directory (which will be checked |
719 | information on readdir. |
253 | seperately). |
|
|
254 | |
720 | |
255 | If the known number of directories has been reached, the rest of the |
721 | If the known number of directories (link count - 2) has been |
256 | entries is assumed to be non-directories. |
722 | reached, the rest of the entries is assumed to be non-directories. |
|
|
723 | |
|
|
724 | This only works with certainty on POSIX (= UNIX) filesystems, which |
|
|
725 | fortunately are the vast majority of filesystems around. |
|
|
726 | |
|
|
727 | It will also likely work on non-POSIX filesystems with reduced |
|
|
728 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
729 | disables the directory counting heuristic. |
|
|
730 | |
|
|
731 | aio_rmtree $path, $callback->($status) |
|
|
732 | Delete a directory tree starting (and including) $path, return the |
|
|
733 | status of the final "rmdir" only. This is a composite request that |
|
|
734 | uses "aio_scandir" to recurse into and rmdir directories, and unlink |
|
|
735 | everything else. |
|
|
736 | |
|
|
737 | aio_sync $callback->($status) |
|
|
738 | Asynchronously call sync and call the callback when finished. |
257 | |
739 | |
258 | aio_fsync $fh, $callback->($status) |
740 | aio_fsync $fh, $callback->($status) |
259 | Asynchronously call fsync on the given filehandle and call the |
741 | Asynchronously call fsync on the given filehandle and call the |
260 | callback with the fsync result code. |
742 | callback with the fsync result code. |
261 | |
743 | |
… | |
… | |
264 | callback with the fdatasync result code. |
746 | callback with the fdatasync result code. |
265 | |
747 | |
266 | If this call isn't available because your OS lacks it or it couldn't |
748 | If this call isn't available because your OS lacks it or it couldn't |
267 | be detected, it will be emulated by calling "fsync" instead. |
749 | be detected, it will be emulated by calling "fsync" instead. |
268 | |
750 | |
|
|
751 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
|
|
752 | Sync the data portion of the file specified by $offset and $length |
|
|
753 | to disk (but NOT the metadata), by calling the Linux-specific |
|
|
754 | sync_file_range call. If sync_file_range is not available or it |
|
|
755 | returns ENOSYS, then fdatasync or fsync is being substituted. |
|
|
756 | |
|
|
757 | $flags can be a combination of |
|
|
758 | "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", |
|
|
759 | "IO::AIO::SYNC_FILE_RANGE_WRITE" and |
|
|
760 | "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range |
|
|
761 | manpage for details. |
|
|
762 | |
|
|
763 | aio_pathsync $path, $callback->($status) |
|
|
764 | This request tries to open, fsync and close the given path. This is |
|
|
765 | a composite request intended to sync directories after directory |
|
|
766 | operations (E.g. rename). This might not work on all operating |
|
|
767 | systems or have any specific effect, but usually it makes sure that |
|
|
768 | directory changes get written to disc. It works for anything that |
|
|
769 | can be opened for read-only, not just directories. |
|
|
770 | |
|
|
771 | Future versions of this function might fall back to other methods |
|
|
772 | when "fsync" on the directory fails (such as calling "sync"). |
|
|
773 | |
|
|
774 | Passes 0 when everything went ok, and -1 on error. |
|
|
775 | |
|
|
776 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
777 | $callback->($status) |
|
|
778 | This is a rather advanced IO::AIO call, which only works on |
|
|
779 | mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it |
|
|
780 | also works on data scalars managed by the Sys::Mmap or Mmap modules, |
|
|
781 | note that the scalar must only be modified in-place while an aio |
|
|
782 | operation is pending on it). |
|
|
783 | |
|
|
784 | It calls the "msync" function of your OS, if available, with the |
|
|
785 | memory area starting at $offset in the string and ending $length |
|
|
786 | bytes later. If $length is negative, counts from the end, and if |
|
|
787 | $length is "undef", then it goes till the end of the string. The |
|
|
788 | flags can be a combination of "IO::AIO::MS_ASYNC", |
|
|
789 | "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". |
|
|
790 | |
|
|
791 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
792 | $callback->($status) |
|
|
793 | This is a rather advanced IO::AIO call, which works best on |
|
|
794 | mmap(2)ed scalars. |
|
|
795 | |
|
|
796 | It touches (reads or writes) all memory pages in the specified range |
|
|
797 | inside the scalar. All caveats and parameters are the same as for |
|
|
798 | "aio_msync", above, except for flags, which must be either 0 (which |
|
|
799 | reads all pages and ensures they are instantiated) or |
|
|
800 | "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading |
|
|
801 | and writing an octet from it, which dirties the page). |
|
|
802 | |
|
|
803 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
|
|
804 | This is a rather advanced IO::AIO call, which works best on |
|
|
805 | mmap(2)ed scalars. |
|
|
806 | |
|
|
807 | It reads in all the pages of the underlying storage into memory (if |
|
|
808 | any) and locks them, so they are not getting swapped/paged out or |
|
|
809 | removed. |
|
|
810 | |
|
|
811 | If $length is undefined, then the scalar will be locked till the |
|
|
812 | end. |
|
|
813 | |
|
|
814 | On systems that do not implement "mlock", this function returns -1 |
|
|
815 | and sets errno to "ENOSYS". |
|
|
816 | |
|
|
817 | Note that the corresponding "munlock" is synchronous and is |
|
|
818 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
819 | |
|
|
820 | Example: open a file, mmap and mlock it - both will be undone when |
|
|
821 | $data gets destroyed. |
|
|
822 | |
|
|
823 | open my $fh, "<", $path or die "$path: $!"; |
|
|
824 | my $data; |
|
|
825 | IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
|
|
826 | aio_mlock $data; # mlock in background |
|
|
827 | |
|
|
828 | aio_mlockall $flags, $callback->($status) |
|
|
829 | Calls the "mlockall" function with the given $flags (a combination |
|
|
830 | of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). |
|
|
831 | |
|
|
832 | On systems that do not implement "mlockall", this function returns |
|
|
833 | -1 and sets errno to "ENOSYS". |
|
|
834 | |
|
|
835 | Note that the corresponding "munlockall" is synchronous and is |
|
|
836 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
837 | |
|
|
838 | Example: asynchronously lock all current and future pages into |
|
|
839 | memory. |
|
|
840 | |
|
|
841 | aio_mlockall IO::AIO::MCL_FUTURE; |
|
|
842 | |
|
|
843 | aio_group $callback->(...) |
|
|
844 | This is a very special aio request: Instead of doing something, it |
|
|
845 | is a container for other aio requests, which is useful if you want |
|
|
846 | to bundle many requests into a single, composite, request with a |
|
|
847 | definite callback and the ability to cancel the whole request with |
|
|
848 | its subrequests. |
|
|
849 | |
|
|
850 | Returns an object of class IO::AIO::GRP. See its documentation below |
|
|
851 | for more info. |
|
|
852 | |
|
|
853 | Example: |
|
|
854 | |
|
|
855 | my $grp = aio_group sub { |
|
|
856 | print "all stats done\n"; |
|
|
857 | }; |
|
|
858 | |
|
|
859 | add $grp |
|
|
860 | (aio_stat ...), |
|
|
861 | (aio_stat ...), |
|
|
862 | ...; |
|
|
863 | |
|
|
864 | aio_nop $callback->() |
|
|
865 | This is a special request - it does nothing in itself and is only |
|
|
866 | used for side effects, such as when you want to add a dummy request |
|
|
867 | to a group so that finishing the requests in the group depends on |
|
|
868 | executing the given code. |
|
|
869 | |
|
|
870 | While this request does nothing, it still goes through the execution |
|
|
871 | phase and still requires a worker thread. Thus, the callback will |
|
|
872 | not be executed immediately but only after other requests in the |
|
|
873 | queue have entered their execution phase. This can be used to |
|
|
874 | measure request latency. |
|
|
875 | |
|
|
876 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
|
|
877 | Mainly used for debugging and benchmarking, this aio request puts |
|
|
878 | one of the request workers to sleep for the given time. |
|
|
879 | |
|
|
880 | While it is theoretically handy to have simple I/O scheduling |
|
|
881 | requests like sleep and file handle readable/writable, the overhead |
|
|
882 | this creates is immense (it blocks a thread for a long time) so do |
|
|
883 | not use this function except to put your application under |
|
|
884 | artificial I/O pressure. |
|
|
885 | |
|
|
886 | IO::AIO::REQ CLASS |
|
|
887 | All non-aggregate "aio_*" functions return an object of this class when |
|
|
888 | called in non-void context. |
|
|
889 | |
|
|
890 | cancel $req |
|
|
891 | Cancels the request, if possible. Has the effect of skipping |
|
|
892 | execution when entering the execute state and skipping calling the |
|
|
893 | callback when entering the the result state, but will leave the |
|
|
894 | request otherwise untouched (with the exception of readdir). That |
|
|
895 | means that requests that currently execute will not be stopped and |
|
|
896 | resources held by the request will not be freed prematurely. |
|
|
897 | |
|
|
898 | cb $req $callback->(...) |
|
|
899 | Replace (or simply set) the callback registered to the request. |
|
|
900 | |
|
|
901 | IO::AIO::GRP CLASS |
|
|
902 | This class is a subclass of IO::AIO::REQ, so all its methods apply to |
|
|
903 | objects of this class, too. |
|
|
904 | |
|
|
905 | A IO::AIO::GRP object is a special request that can contain multiple |
|
|
906 | other aio requests. |
|
|
907 | |
|
|
908 | You create one by calling the "aio_group" constructing function with a |
|
|
909 | callback that will be called when all contained requests have entered |
|
|
910 | the "done" state: |
|
|
911 | |
|
|
912 | my $grp = aio_group sub { |
|
|
913 | print "all requests are done\n"; |
|
|
914 | }; |
|
|
915 | |
|
|
916 | You add requests by calling the "add" method with one or more |
|
|
917 | "IO::AIO::REQ" objects: |
|
|
918 | |
|
|
919 | $grp->add (aio_unlink "..."); |
|
|
920 | |
|
|
921 | add $grp aio_stat "...", sub { |
|
|
922 | $_[0] or return $grp->result ("error"); |
|
|
923 | |
|
|
924 | # add another request dynamically, if first succeeded |
|
|
925 | add $grp aio_open "...", sub { |
|
|
926 | $grp->result ("ok"); |
|
|
927 | }; |
|
|
928 | }; |
|
|
929 | |
|
|
930 | This makes it very easy to create composite requests (see the source of |
|
|
931 | "aio_move" for an application) that work and feel like simple requests. |
|
|
932 | |
|
|
933 | * The IO::AIO::GRP objects will be cleaned up during calls to |
|
|
934 | "IO::AIO::poll_cb", just like any other request. |
|
|
935 | |
|
|
936 | * They can be canceled like any other request. Canceling will cancel |
|
|
937 | not only the request itself, but also all requests it contains. |
|
|
938 | |
|
|
939 | * They can also can also be added to other IO::AIO::GRP objects. |
|
|
940 | |
|
|
941 | * You must not add requests to a group from within the group callback |
|
|
942 | (or any later time). |
|
|
943 | |
|
|
944 | Their lifetime, simplified, looks like this: when they are empty, they |
|
|
945 | will finish very quickly. If they contain only requests that are in the |
|
|
946 | "done" state, they will also finish. Otherwise they will continue to |
|
|
947 | exist. |
|
|
948 | |
|
|
949 | That means after creating a group you have some time to add requests |
|
|
950 | (precisely before the callback has been invoked, which is only done |
|
|
951 | within the "poll_cb"). And in the callbacks of those requests, you can |
|
|
952 | add further requests to the group. And only when all those requests have |
|
|
953 | finished will the the group itself finish. |
|
|
954 | |
|
|
955 | add $grp ... |
|
|
956 | $grp->add (...) |
|
|
957 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
|
|
958 | be added, including other groups, as long as you do not create |
|
|
959 | circular dependencies. |
|
|
960 | |
|
|
961 | Returns all its arguments. |
|
|
962 | |
|
|
963 | $grp->cancel_subs |
|
|
964 | Cancel all subrequests and clears any feeder, but not the group |
|
|
965 | request itself. Useful when you queued a lot of events but got a |
|
|
966 | result early. |
|
|
967 | |
|
|
968 | The group request will finish normally (you cannot add requests to |
|
|
969 | the group). |
|
|
970 | |
|
|
971 | $grp->result (...) |
|
|
972 | Set the result value(s) that will be passed to the group callback |
|
|
973 | when all subrequests have finished and set the groups errno to the |
|
|
974 | current value of errno (just like calling "errno" without an error |
|
|
975 | number). By default, no argument will be passed and errno is zero. |
|
|
976 | |
|
|
977 | $grp->errno ([$errno]) |
|
|
978 | Sets the group errno value to $errno, or the current value of errno |
|
|
979 | when the argument is missing. |
|
|
980 | |
|
|
981 | Every aio request has an associated errno value that is restored |
|
|
982 | when the callback is invoked. This method lets you change this value |
|
|
983 | from its default (0). |
|
|
984 | |
|
|
985 | Calling "result" will also set errno, so make sure you either set $! |
|
|
986 | before the call to "result", or call c<errno> after it. |
|
|
987 | |
|
|
988 | feed $grp $callback->($grp) |
|
|
989 | Sets a feeder/generator on this group: every group can have an |
|
|
990 | attached generator that generates requests if idle. The idea behind |
|
|
991 | this is that, although you could just queue as many requests as you |
|
|
992 | want in a group, this might starve other requests for a potentially |
|
|
993 | long time. For example, "aio_scandir" might generate hundreds of |
|
|
994 | thousands "aio_stat" requests, delaying any later requests for a |
|
|
995 | long time. |
|
|
996 | |
|
|
997 | To avoid this, and allow incremental generation of requests, you can |
|
|
998 | instead a group and set a feeder on it that generates those |
|
|
999 | requests. The feed callback will be called whenever there are few |
|
|
1000 | enough (see "limit", below) requests active in the group itself and |
|
|
1001 | is expected to queue more requests. |
|
|
1002 | |
|
|
1003 | The feed callback can queue as many requests as it likes (i.e. "add" |
|
|
1004 | does not impose any limits). |
|
|
1005 | |
|
|
1006 | If the feed does not queue more requests when called, it will be |
|
|
1007 | automatically removed from the group. |
|
|
1008 | |
|
|
1009 | If the feed limit is 0 when this method is called, it will be set to |
|
|
1010 | 2 automatically. |
|
|
1011 | |
|
|
1012 | Example: |
|
|
1013 | |
|
|
1014 | # stat all files in @files, but only ever use four aio requests concurrently: |
|
|
1015 | |
|
|
1016 | my $grp = aio_group sub { print "finished\n" }; |
|
|
1017 | limit $grp 4; |
|
|
1018 | feed $grp sub { |
|
|
1019 | my $file = pop @files |
|
|
1020 | or return; |
|
|
1021 | |
|
|
1022 | add $grp aio_stat $file, sub { ... }; |
|
|
1023 | }; |
|
|
1024 | |
|
|
1025 | limit $grp $num |
|
|
1026 | Sets the feeder limit for the group: The feeder will be called |
|
|
1027 | whenever the group contains less than this many requests. |
|
|
1028 | |
|
|
1029 | Setting the limit to 0 will pause the feeding process. |
|
|
1030 | |
|
|
1031 | The default value for the limit is 0, but note that setting a feeder |
|
|
1032 | automatically bumps it up to 2. |
|
|
1033 | |
269 | SUPPORT FUNCTIONS |
1034 | SUPPORT FUNCTIONS |
|
|
1035 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
270 | $fileno = IO::AIO::poll_fileno |
1036 | $fileno = IO::AIO::poll_fileno |
271 | Return the *request result pipe file descriptor*. This filehandle |
1037 | Return the *request result pipe file descriptor*. This filehandle |
272 | must be polled for reading by some mechanism outside this module |
1038 | must be polled for reading by some mechanism outside this module |
273 | (e.g. Event or select, see below or the SYNOPSIS). If the pipe |
1039 | (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the |
274 | becomes readable you have to call "poll_cb" to check the results. |
1040 | pipe becomes readable you have to call "poll_cb" to check the |
|
|
1041 | results. |
275 | |
1042 | |
276 | See "poll_cb" for an example. |
1043 | See "poll_cb" for an example. |
277 | |
1044 | |
278 | IO::AIO::poll_cb |
1045 | IO::AIO::poll_cb |
279 | Process all outstanding events on the result pipe. You have to call |
1046 | Process some outstanding events on the result pipe. You have to call |
280 | this regularly. Returns the number of events processed. Returns |
1047 | this regularly. Returns 0 if all events could be processed (or there |
|
|
1048 | were no events to process), or -1 if it returned earlier for |
281 | immediately when no events are outstanding. |
1049 | whatever reason. Returns immediately when no events are outstanding. |
|
|
1050 | The amount of events processed depends on the settings of |
|
|
1051 | "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". |
|
|
1052 | |
|
|
1053 | If not all requests were processed for whatever reason, the |
|
|
1054 | filehandle will still be ready when "poll_cb" returns, so normally |
|
|
1055 | you don't have to do anything special to have it called later. |
|
|
1056 | |
|
|
1057 | Apart from calling "IO::AIO::poll_cb" when the event filehandle |
|
|
1058 | becomes ready, it can be beneficial to call this function from loops |
|
|
1059 | which submit a lot of requests, to make sure the results get |
|
|
1060 | processed when they become available and not just when the loop is |
|
|
1061 | finished and the event loop takes over again. This function returns |
|
|
1062 | very fast when there are no outstanding requests. |
282 | |
1063 | |
283 | Example: Install an Event watcher that automatically calls |
1064 | Example: Install an Event watcher that automatically calls |
284 | IO::AIO::poll_cb with high priority: |
1065 | IO::AIO::poll_cb with high priority (more examples can be found in |
|
|
1066 | the SYNOPSIS section, at the top of this document): |
285 | |
1067 | |
286 | Event->io (fd => IO::AIO::poll_fileno, |
1068 | Event->io (fd => IO::AIO::poll_fileno, |
287 | poll => 'r', async => 1, |
1069 | poll => 'r', async => 1, |
288 | cb => \&IO::AIO::poll_cb); |
1070 | cb => \&IO::AIO::poll_cb); |
289 | |
1071 | |
290 | IO::AIO::poll_wait |
1072 | IO::AIO::poll_wait |
|
|
1073 | If there are any outstanding requests and none of them in the result |
291 | Wait till the result filehandle becomes ready for reading (simply |
1074 | phase, wait till the result filehandle becomes ready for reading |
292 | does a "select" on the filehandle. This is useful if you want to |
1075 | (simply does a "select" on the filehandle. This is useful if you |
293 | synchronously wait for some requests to finish). |
1076 | want to synchronously wait for some requests to finish). |
294 | |
1077 | |
295 | See "nreqs" for an example. |
1078 | See "nreqs" for an example. |
296 | |
1079 | |
|
|
1080 | IO::AIO::poll |
|
|
1081 | Waits until some requests have been handled. |
|
|
1082 | |
|
|
1083 | Returns the number of requests processed, but is otherwise strictly |
|
|
1084 | equivalent to: |
|
|
1085 | |
|
|
1086 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1087 | |
297 | IO::AIO::nreqs |
1088 | IO::AIO::flush |
298 | Returns the number of requests currently outstanding (i.e. for which |
1089 | Wait till all outstanding AIO requests have been handled. |
299 | their callback has not been invoked yet). |
|
|
300 | |
1090 | |
301 | Example: wait till there are no outstanding requests anymore: |
1091 | Strictly equivalent to: |
302 | |
1092 | |
303 | IO::AIO::poll_wait, IO::AIO::poll_cb |
1093 | IO::AIO::poll_wait, IO::AIO::poll_cb |
304 | while IO::AIO::nreqs; |
1094 | while IO::AIO::nreqs; |
305 | |
1095 | |
306 | IO::AIO::flush |
1096 | IO::AIO::max_poll_reqs $nreqs |
307 | Wait till all outstanding AIO requests have been handled. |
1097 | IO::AIO::max_poll_time $seconds |
|
|
1098 | These set the maximum number of requests (default 0, meaning |
|
|
1099 | infinity) that are being processed by "IO::AIO::poll_cb" in one |
|
|
1100 | call, respectively the maximum amount of time (default 0, meaning |
|
|
1101 | infinity) spent in "IO::AIO::poll_cb" to process requests (more |
|
|
1102 | correctly the mininum amount of time "poll_cb" is allowed to use). |
308 | |
1103 | |
309 | Strictly equivalent to: |
1104 | Setting "max_poll_time" to a non-zero value creates an overhead of |
|
|
1105 | one syscall per request processed, which is not normally a problem |
|
|
1106 | unless your callbacks are really really fast or your OS is really |
|
|
1107 | really slow (I am not mentioning Solaris here). Using |
|
|
1108 | "max_poll_reqs" incurs no overhead. |
310 | |
1109 | |
311 | IO::AIO::poll_wait, IO::AIO::poll_cb |
1110 | Setting these is useful if you want to ensure some level of |
312 | while IO::AIO::nreqs; |
1111 | interactiveness when perl is not fast enough to process all requests |
|
|
1112 | in time. |
313 | |
1113 | |
314 | IO::AIO::poll |
1114 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
315 | Waits until some requests have been handled. |
|
|
316 | |
1115 | |
317 | Strictly equivalent to: |
1116 | Example: Install an Event watcher that automatically calls |
|
|
1117 | IO::AIO::poll_cb with low priority, to ensure that other parts of |
|
|
1118 | the program get the CPU sometimes even under high AIO load. |
318 | |
1119 | |
319 | IO::AIO::poll_wait, IO::AIO::poll_cb |
1120 | # try not to spend much more than 0.1s in poll_cb |
320 | if IO::AIO::nreqs; |
1121 | IO::AIO::max_poll_time 0.1; |
321 | |
1122 | |
|
|
1123 | # use a low priority so other tasks have priority |
|
|
1124 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1125 | poll => 'r', nice => 1, |
|
|
1126 | cb => &IO::AIO::poll_cb); |
|
|
1127 | |
|
|
1128 | CONTROLLING THE NUMBER OF THREADS |
322 | IO::AIO::min_parallel $nthreads |
1129 | IO::AIO::min_parallel $nthreads |
323 | Set the minimum number of AIO threads to $nthreads. The current |
1130 | Set the minimum number of AIO threads to $nthreads. The current |
324 | default is 4, which means four asynchronous operations can be done |
1131 | default is 8, which means eight asynchronous operations can execute |
325 | at one time (the number of outstanding operations, however, is |
1132 | concurrently at any one time (the number of outstanding requests, |
326 | unlimited). |
1133 | however, is unlimited). |
327 | |
1134 | |
328 | IO::AIO starts threads only on demand, when an AIO request is queued |
1135 | IO::AIO starts threads only on demand, when an AIO request is queued |
329 | and no free thread exists. |
1136 | and no free thread exists. Please note that queueing up a hundred |
|
|
1137 | requests can create demand for a hundred threads, even if it turns |
|
|
1138 | out that everything is in the cache and could have been processed |
|
|
1139 | faster by a single thread. |
330 | |
1140 | |
331 | It is recommended to keep the number of threads low, as some Linux |
1141 | It is recommended to keep the number of threads relatively low, as |
332 | kernel versions will scale negatively with the number of threads |
1142 | some Linux kernel versions will scale negatively with the number of |
333 | (higher parallelity => MUCH higher latency). With current Linux 2.6 |
1143 | threads (higher parallelity => MUCH higher latency). With current |
334 | versions, 4-32 threads should be fine. |
1144 | Linux 2.6 versions, 4-32 threads should be fine. |
335 | |
1145 | |
336 | Under most circumstances you don't need to call this function, as |
1146 | Under most circumstances you don't need to call this function, as |
337 | the module selects a default that is suitable for low to moderate |
1147 | the module selects a default that is suitable for low to moderate |
338 | load. |
1148 | load. |
339 | |
1149 | |
… | |
… | |
349 | ensure that all threads are killed and that there are no outstanding |
1159 | ensure that all threads are killed and that there are no outstanding |
350 | requests. |
1160 | requests. |
351 | |
1161 | |
352 | Under normal circumstances you don't need to call this function. |
1162 | Under normal circumstances you don't need to call this function. |
353 | |
1163 | |
|
|
1164 | IO::AIO::max_idle $nthreads |
|
|
1165 | Limit the number of threads (default: 4) that are allowed to idle |
|
|
1166 | (i.e., threads that did not get a request to process within the idle |
|
|
1167 | timeout (default: 10 seconds). That means if a thread becomes idle |
|
|
1168 | while $nthreads other threads are also idle, it will free its |
|
|
1169 | resources and exit. |
|
|
1170 | |
|
|
1171 | This is useful when you allow a large number of threads (e.g. 100 or |
|
|
1172 | 1000) to allow for extremely high load situations, but want to free |
|
|
1173 | resources under normal circumstances (1000 threads can easily |
|
|
1174 | consume 30MB of RAM). |
|
|
1175 | |
|
|
1176 | The default is probably ok in most situations, especially if thread |
|
|
1177 | creation is fast. If thread creation is very slow on your system you |
|
|
1178 | might want to use larger values. |
|
|
1179 | |
|
|
1180 | IO::AIO::idle_timeout $seconds |
|
|
1181 | Sets the minimum idle timeout (default 10) after which worker |
|
|
1182 | threads are allowed to exit. SEe "IO::AIO::max_idle". |
|
|
1183 | |
354 | $oldnreqs = IO::AIO::max_outstanding $nreqs |
1184 | IO::AIO::max_outstanding $maxreqs |
355 | Sets the maximum number of outstanding requests to $nreqs. If you |
1185 | Sets the maximum number of outstanding requests to $nreqs. If you do |
356 | try to queue up more than this number of requests, the caller will |
1186 | queue up more than this number of requests, the next call to |
|
|
1187 | "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as |
|
|
1188 | "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is |
|
|
1189 | no longer exceeded. |
|
|
1190 | |
|
|
1191 | In other words, this setting does not enforce a queue limit, but can |
|
|
1192 | be used to make poll functions block if the limit is exceeded. |
|
|
1193 | |
|
|
1194 | This is a very bad function to use in interactive programs because |
|
|
1195 | it blocks, and a bad way to reduce concurrency because it is |
|
|
1196 | inexact: Better use an "aio_group" together with a feed callback. |
|
|
1197 | |
|
|
1198 | It's main use is in scripts without an event loop - when you want to |
|
|
1199 | stat a lot of files, you can write somehting like this: |
|
|
1200 | |
|
|
1201 | IO::AIO::max_outstanding 32; |
|
|
1202 | |
|
|
1203 | for my $path (...) { |
|
|
1204 | aio_stat $path , ...; |
|
|
1205 | IO::AIO::poll_cb; |
|
|
1206 | } |
|
|
1207 | |
|
|
1208 | IO::AIO::flush; |
|
|
1209 | |
|
|
1210 | The call to "poll_cb" inside the loop will normally return |
|
|
1211 | instantly, but as soon as more thna 32 reqeusts are in-flight, it |
357 | block until some requests have been handled. |
1212 | will block until some requests have been handled. This keeps the |
|
|
1213 | loop from pushing a large number of "aio_stat" requests onto the |
|
|
1214 | queue. |
358 | |
1215 | |
359 | The default is very large, so normally there is no practical limit. |
1216 | The default value for "max_outstanding" is very large, so there is |
360 | If you queue up many requests in a loop it often improves speed if |
1217 | no practical limit on the number of outstanding requests. |
361 | you set this to a relatively low number, such as 100. |
|
|
362 | |
1218 | |
363 | Under normal circumstances you don't need to call this function. |
1219 | STATISTICAL INFORMATION |
|
|
1220 | IO::AIO::nreqs |
|
|
1221 | Returns the number of requests currently in the ready, execute or |
|
|
1222 | pending states (i.e. for which their callback has not been invoked |
|
|
1223 | yet). |
|
|
1224 | |
|
|
1225 | Example: wait till there are no outstanding requests anymore: |
|
|
1226 | |
|
|
1227 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1228 | while IO::AIO::nreqs; |
|
|
1229 | |
|
|
1230 | IO::AIO::nready |
|
|
1231 | Returns the number of requests currently in the ready state (not yet |
|
|
1232 | executed). |
|
|
1233 | |
|
|
1234 | IO::AIO::npending |
|
|
1235 | Returns the number of requests currently in the pending state |
|
|
1236 | (executed, but not yet processed by poll_cb). |
|
|
1237 | |
|
|
1238 | MISCELLANEOUS FUNCTIONS |
|
|
1239 | IO::AIO implements some functions that might be useful, but are not |
|
|
1240 | asynchronous. |
|
|
1241 | |
|
|
1242 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
|
|
1243 | Calls the "eio_sendfile_sync" function, which is like |
|
|
1244 | "aio_sendfile", but is blocking (this makes most sense if you know |
|
|
1245 | the input data is likely cached already and the output filehandle is |
|
|
1246 | set to non-blocking operations). |
|
|
1247 | |
|
|
1248 | Returns the number of bytes copied, or -1 on error. |
|
|
1249 | |
|
|
1250 | IO::AIO::fadvise $fh, $offset, $len, $advice |
|
|
1251 | Simply calls the "posix_fadvise" function (see its manpage for |
|
|
1252 | details). The following advice constants are avaiable: |
|
|
1253 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
|
|
1254 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
|
|
1255 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
|
|
1256 | |
|
|
1257 | On systems that do not implement "posix_fadvise", this function |
|
|
1258 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
|
|
1259 | |
|
|
1260 | IO::AIO::madvise $scalar, $offset, $len, $advice |
|
|
1261 | Simply calls the "posix_madvise" function (see its manpage for |
|
|
1262 | details). The following advice constants are avaiable: |
|
|
1263 | "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", |
|
|
1264 | "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", |
|
|
1265 | "IO::AIO::MADV_DONTNEED". |
|
|
1266 | |
|
|
1267 | On systems that do not implement "posix_madvise", this function |
|
|
1268 | returns ENOSYS, otherwise the return value of "posix_madvise". |
|
|
1269 | |
|
|
1270 | IO::AIO::mprotect $scalar, $offset, $len, $protect |
|
|
1271 | Simply calls the "mprotect" function on the preferably AIO::mmap'ed |
|
|
1272 | $scalar (see its manpage for details). The following protect |
|
|
1273 | constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", |
|
|
1274 | "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". |
|
|
1275 | |
|
|
1276 | On systems that do not implement "mprotect", this function returns |
|
|
1277 | ENOSYS, otherwise the return value of "mprotect". |
|
|
1278 | |
|
|
1279 | IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
|
|
1280 | Memory-maps a file (or anonymous memory range) and attaches it to |
|
|
1281 | the given $scalar, which will act like a string scalar. |
|
|
1282 | |
|
|
1283 | The only operations allowed on the scalar are "substr"/"vec" that |
|
|
1284 | don't change the string length, and most read-only operations such |
|
|
1285 | as copying it or searching it with regexes and so on. |
|
|
1286 | |
|
|
1287 | Anything else is unsafe and will, at best, result in memory leaks. |
|
|
1288 | |
|
|
1289 | The memory map associated with the $scalar is automatically removed |
|
|
1290 | when the $scalar is destroyed, or when the "IO::AIO::mmap" or |
|
|
1291 | "IO::AIO::munmap" functions are called. |
|
|
1292 | |
|
|
1293 | This calls the "mmap"(2) function internally. See your system's |
|
|
1294 | manual page for details on the $length, $prot and $flags parameters. |
|
|
1295 | |
|
|
1296 | The $length must be larger than zero and smaller than the actual |
|
|
1297 | filesize. |
|
|
1298 | |
|
|
1299 | $prot is a combination of "IO::AIO::PROT_NONE", |
|
|
1300 | "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or |
|
|
1301 | "IO::AIO::PROT_WRITE", |
|
|
1302 | |
|
|
1303 | $flags can be a combination of "IO::AIO::MAP_SHARED" or |
|
|
1304 | "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when |
|
|
1305 | not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" |
|
|
1306 | (which is set to "MAP_ANON" if your system only provides this |
|
|
1307 | constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", |
|
|
1308 | "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or |
|
|
1309 | "IO::AIO::MAP_NONBLOCK" |
|
|
1310 | |
|
|
1311 | If $fh is "undef", then a file descriptor of -1 is passed. |
|
|
1312 | |
|
|
1313 | $offset is the offset from the start of the file - it generally must |
|
|
1314 | be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. |
|
|
1315 | |
|
|
1316 | Example: |
|
|
1317 | |
|
|
1318 | use Digest::MD5; |
|
|
1319 | use IO::AIO; |
|
|
1320 | |
|
|
1321 | open my $fh, "<verybigfile" |
|
|
1322 | or die "$!"; |
|
|
1323 | |
|
|
1324 | IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh |
|
|
1325 | or die "verybigfile: $!"; |
|
|
1326 | |
|
|
1327 | my $fast_md5 = md5 $data; |
|
|
1328 | |
|
|
1329 | IO::AIO::munmap $scalar |
|
|
1330 | Removes a previous mmap and undefines the $scalar. |
|
|
1331 | |
|
|
1332 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
|
|
1333 | Calls the "munlock" function, undoing the effects of a previous |
|
|
1334 | "aio_mlock" call (see its description for details). |
|
|
1335 | |
|
|
1336 | IO::AIO::munlockall |
|
|
1337 | Calls the "munlockall" function. |
|
|
1338 | |
|
|
1339 | On systems that do not implement "munlockall", this function returns |
|
|
1340 | ENOSYS, otherwise the return value of "munlockall". |
|
|
1341 | |
|
|
1342 | EVENT LOOP INTEGRATION |
|
|
1343 | It is recommended to use AnyEvent::AIO to integrate IO::AIO |
|
|
1344 | automatically into many event loops: |
|
|
1345 | |
|
|
1346 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
|
|
1347 | use AnyEvent::AIO; |
|
|
1348 | |
|
|
1349 | You can also integrate IO::AIO manually into many event loops, here are |
|
|
1350 | some examples of how to do this: |
|
|
1351 | |
|
|
1352 | # EV integration |
|
|
1353 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
|
|
1354 | |
|
|
1355 | # Event integration |
|
|
1356 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1357 | poll => 'r', |
|
|
1358 | cb => \&IO::AIO::poll_cb); |
|
|
1359 | |
|
|
1360 | # Glib/Gtk2 integration |
|
|
1361 | add_watch Glib::IO IO::AIO::poll_fileno, |
|
|
1362 | in => sub { IO::AIO::poll_cb; 1 }; |
|
|
1363 | |
|
|
1364 | # Tk integration |
|
|
1365 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
|
|
1366 | readable => \&IO::AIO::poll_cb); |
|
|
1367 | |
|
|
1368 | # Danga::Socket integration |
|
|
1369 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
|
|
1370 | \&IO::AIO::poll_cb); |
364 | |
1371 | |
365 | FORK BEHAVIOUR |
1372 | FORK BEHAVIOUR |
366 | Before the fork, IO::AIO enters a quiescent state where no requests can |
1373 | Usage of pthreads in a program changes the semantics of fork |
367 | be added in other threads and no results will be processed. After the |
1374 | considerably. Specifically, only async-safe functions can be called |
368 | fork the parent simply leaves the quiescent state and continues |
1375 | after fork. Perl doesn't know about this, so in general, you cannot call |
369 | request/result processing, while the child clears the request/result |
1376 | fork with defined behaviour in perl. IO::AIO uses pthreads, so this |
370 | queue (so the requests started before the fork will only be handled in |
1377 | applies, but many other extensions and (for inexplicable reasons) perl |
371 | the parent). Threats will be started on demand until the limit ste in |
1378 | itself often is linked against pthreads, so this limitation applies. |
372 | the parent process has been reached again. |
1379 | |
|
|
1380 | Some operating systems have extensions that allow safe use of fork, and |
|
|
1381 | this module should do "the right thing" on those, and tries on others. |
|
|
1382 | At the time of this writing (2011) only GNU/Linux supports these |
|
|
1383 | extensions to POSIX. |
|
|
1384 | |
|
|
1385 | MEMORY USAGE |
|
|
1386 | Per-request usage: |
|
|
1387 | |
|
|
1388 | Each aio request uses - depending on your architecture - around 100-200 |
|
|
1389 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
|
|
1390 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
|
|
1391 | scalars and other data passed into aio requests will also be locked and |
|
|
1392 | will consume memory till the request has entered the done state. |
|
|
1393 | |
|
|
1394 | This is not awfully much, so queuing lots of requests is not usually a |
|
|
1395 | problem. |
|
|
1396 | |
|
|
1397 | Per-thread usage: |
|
|
1398 | |
|
|
1399 | In the execution phase, some aio requests require more memory for |
|
|
1400 | temporary buffers, and each thread requires a stack and other data |
|
|
1401 | structures (usually around 16k-128k, depending on the OS). |
|
|
1402 | |
|
|
1403 | KNOWN BUGS |
|
|
1404 | Known bugs will be fixed in the next release. |
373 | |
1405 | |
374 | SEE ALSO |
1406 | SEE ALSO |
375 | Coro, Linux::AIO. |
1407 | AnyEvent::AIO for easy integration into event loops, Coro::AIO for a |
|
|
1408 | more natural syntax. |
376 | |
1409 | |
377 | AUTHOR |
1410 | AUTHOR |
378 | Marc Lehmann <schmorp@schmorp.de> |
1411 | Marc Lehmann <schmorp@schmorp.de> |
379 | http://home.schmorp.de/ |
1412 | http://home.schmorp.de/ |
380 | |
1413 | |