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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 | |
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23 | $req->cancel; # cancel request if still in queue |
24 | $req->cancel; # cancel request if still in queue |
24 | |
25 | |
25 | my $grp = aio_group sub { print "all stats done\n" }; |
26 | my $grp = aio_group sub { print "all stats done\n" }; |
26 | add $grp aio_stat "..." for ...; |
27 | add $grp aio_stat "..." for ...; |
27 | |
28 | |
28 | # AnyEvent integration |
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29 | open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!"; |
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30 | my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb }); |
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31 | |
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32 | # Event integration |
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33 | Event->io (fd => IO::AIO::poll_fileno, |
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34 | poll => 'r', |
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35 | cb => \&IO::AIO::poll_cb); |
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36 | |
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37 | # Glib/Gtk2 integration |
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38 | add_watch Glib::IO IO::AIO::poll_fileno, |
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39 | in => sub { IO::AIO::poll_cb; 1 }; |
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40 | |
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41 | # Tk integration |
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42 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
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43 | readable => \&IO::AIO::poll_cb); |
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44 | |
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45 | # Danga::Socket integration |
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46 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
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47 | \&IO::AIO::poll_cb); |
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48 | |
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49 | DESCRIPTION |
29 | DESCRIPTION |
50 | This module implements asynchronous I/O using whatever means your |
30 | This module implements asynchronous I/O using whatever means your |
51 | 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>). |
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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. |
52 | |
49 | |
53 | In this version, a number of threads are started that execute your |
50 | In this version, a number of threads are started that execute your |
54 | requests and signal their completion. You don't need thread support in |
51 | requests and signal their completion. You don't need thread support in |
55 | 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 |
56 | perl. In the future, this module might make use of the native aio |
53 | perl. In the future, this module might make use of the native aio |
57 | functions available on many operating systems. However, they are often |
54 | functions available on many operating systems. However, they are often |
58 | not well-supported or restricted (Linux doesn't allow them on normal |
55 | not well-supported or restricted (GNU/Linux doesn't allow them on normal |
59 | files currently, for example), and they would only support aio_read and |
56 | files currently, for example), and they would only support aio_read and |
60 | aio_write, so the remaining functionality would have to be implemented |
57 | aio_write, so the remaining functionality would have to be implemented |
61 | using threads anyway. |
58 | using threads anyway. |
62 | |
59 | |
63 | Although the module will work with in the presence of other (Perl-) |
60 | Although the module will work in the presence of other (Perl-) threads, |
64 | threads, it is currently not reentrant in any way, so use appropriate |
61 | it is currently not reentrant in any way, so use appropriate locking |
65 | locking yourself, always call "poll_cb" from within the same thread, or |
62 | yourself, always call "poll_cb" from within the same thread, or never |
66 | never call "poll_cb" (or 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; |
67 | |
105 | |
68 | REQUEST ANATOMY AND LIFETIME |
106 | REQUEST ANATOMY AND LIFETIME |
69 | Every "aio_*" function creates a request. which is a C data structure |
107 | Every "aio_*" function creates a request. which is a C data structure |
70 | not directly visible to Perl. |
108 | not directly visible to Perl. |
71 | |
109 | |
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107 | anymore (except possibly for the Perl object, but its connection to |
145 | anymore (except possibly for the Perl object, but its connection to |
108 | the actual aio request is severed and calling its methods will |
146 | the actual aio request is severed and calling its methods will |
109 | either do nothing or result in a runtime error). |
147 | either do nothing or result in a runtime error). |
110 | |
148 | |
111 | FUNCTIONS |
149 | FUNCTIONS |
112 | AIO FUNCTIONS |
150 | QUICK OVERVIEW |
113 | All the "aio_*" calls are more or less thin wrappers around the |
151 | This section simply lists the prototypes of the most important functions |
114 | syscall with the same name (sans "aio_"). The arguments are similar |
152 | for quick reference. See the following sections for function-by-function |
115 | or identical, and they all accept an additional (and optional) |
153 | documentation. |
116 | $callback argument which must be a code reference. This code |
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117 | reference will get called with the syscall return code (e.g. most |
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118 | syscalls return -1 on error, unlike perl, which usually delivers |
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119 | "false") as it's sole argument when the given syscall has been |
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120 | executed asynchronously. |
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121 | |
154 | |
122 | All functions expecting a filehandle keep a copy of the filehandle |
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123 | internally until the request has finished. |
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124 | |
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125 | All requests return objects of type IO::AIO::REQ that allow further |
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126 | manipulation of those requests while they are in-flight. |
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127 | |
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128 | The pathnames you pass to these routines *must* be absolute and |
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129 | encoded in byte form. The reason for the former is that at the time |
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130 | the request is being executed, the current working directory could |
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131 | have changed. Alternatively, you can make sure that you never change |
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132 | the current working directory. |
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133 | |
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134 | To encode pathnames to byte form, either make sure you either: a) |
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135 | always pass in filenames you got from outside (command line, readdir |
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136 | etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and |
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137 | encode your pathnames to the locale (or other) encoding in effect in |
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138 | the user environment, d) use Glib::filename_from_unicode on unicode |
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139 | filenames or e) use something else. |
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140 | |
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141 | $prev_pri = aioreq_pri [$pri] |
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142 | Returns the priority value that would be used for the next |
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143 | request and, if $pri is given, sets the priority for the next |
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144 | aio request. |
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145 | |
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146 | The default priority is 0, the minimum and maximum priorities |
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147 | are -4 and 4, respectively. Requests with higher priority will |
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148 | be serviced first. |
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149 | |
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150 | The priority will be reset to 0 after each call to one of the |
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151 | "aio_*" functions. |
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152 | |
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153 | Example: open a file with low priority, then read something from |
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154 | it with higher priority so the read request is serviced before |
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155 | other low priority open requests (potentially spamming the |
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156 | cache): |
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157 | |
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158 | aioreq_pri -3; |
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159 | aio_open ..., sub { |
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160 | return unless $_[0]; |
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161 | |
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162 | aioreq_pri -2; |
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163 | aio_read $_[0], ..., sub { |
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164 | ... |
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165 | }; |
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166 | }; |
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167 | |
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168 | aioreq_nice $pri_adjust |
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169 | Similar to "aioreq_pri", but subtracts the given value from the |
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170 | current priority, so effects are cumulative. |
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171 | |
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172 | aio_open $pathname, $flags, $mode, $callback->($fh) |
155 | aio_open $pathname, $flags, $mode, $callback->($fh) |
173 | Asynchronously open or create a file and call the callback with |
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174 | a newly created filehandle for the file. |
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175 | |
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176 | The pathname passed to "aio_open" must be absolute. See API |
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177 | NOTES, above, for an explanation. |
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178 | |
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179 | The $flags argument is a bitmask. See the "Fcntl" module for a |
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180 | list. They are the same as used by "sysopen". |
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181 | |
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182 | Likewise, $mode specifies the mode of the newly created file, if |
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183 | it didn't exist and "O_CREAT" has been given, just like perl's |
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184 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
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185 | create new files, and 0666 or 0777 if you do). |
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186 | |
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187 | Example: |
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188 | |
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189 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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190 | if ($_[0]) { |
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191 | print "open successful, fh is $_[0]\n"; |
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192 | ... |
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193 | } else { |
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194 | die "open failed: $!\n"; |
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195 | } |
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196 | }; |
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197 | |
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198 | aio_close $fh, $callback->($status) |
156 | aio_close $fh, $callback->($status) |
199 | Asynchronously close a file and call the callback with the |
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200 | result code. *WARNING:* although accepted, you should not pass |
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201 | in a perl filehandle here, as perl will likely close the file |
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202 | descriptor another time when the filehandle is destroyed. |
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203 | Normally, you can safely call perls "close" or just let |
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204 | filehandles go out of scope. |
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205 | |
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206 | This is supposed to be a bug in the API, so that might change. |
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207 | It's therefore best to avoid this function. |
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208 | |
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209 | aio_read $fh,$offset,$length, $data,$dataoffset, |
157 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
210 | $callback->($retval) |
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211 | aio_write $fh,$offset,$length, $data,$dataoffset, |
158 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
212 | $callback->($retval) |
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213 | Reads or writes "length" bytes from the specified "fh" and |
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214 | "offset" into the scalar given by "data" and offset "dataoffset" |
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215 | and calls the callback without the actual number of bytes read |
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216 | (or -1 on error, just like the syscall). |
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217 | |
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218 | The $data scalar *MUST NOT* be modified in any way while the |
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219 | request is outstanding. Modifying it can result in segfaults or |
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220 | WW3 (if the necessary/optional hardware is installed). |
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221 | |
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222 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting |
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223 | at offset 0 within the scalar: |
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224 | |
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225 | aio_read $fh, 7, 15, $buffer, 0, sub { |
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226 | $_[0] > 0 or die "read error: $!"; |
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227 | print "read $_[0] bytes: <$buffer>\n"; |
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228 | }; |
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229 | |
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230 | aio_move $srcpath, $dstpath, $callback->($status) |
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231 | Try to move the *file* (directories not supported as either |
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232 | source or destination) from $srcpath to $dstpath and call the |
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233 | callback with the 0 (error) or -1 ok. |
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234 | |
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235 | This is a composite request that tries to rename(2) the file |
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236 | first. If rename files with "EXDEV", it creates the destination |
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237 | file with mode 0200 and copies the contents of the source file |
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238 | into it using "aio_sendfile", followed by restoring atime, |
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239 | mtime, access mode and uid/gid, in that order, and unlinking the |
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240 | $srcpath. |
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241 | |
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242 | If an error occurs, the partial destination file will be |
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243 | unlinked, if possible, except when setting atime, mtime, access |
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244 | mode and uid/gid, where errors are being ignored. |
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245 | |
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246 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, |
159 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
247 | $callback->($retval) |
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248 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
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249 | reading at byte offset $in_offset, and starts writing at the |
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250 | current file offset of $out_fh. Because of that, it is not safe |
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251 | to issue more than one "aio_sendfile" per $out_fh, as they will |
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252 | interfere with each other. |
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253 | |
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254 | This call tries to make use of a native "sendfile" syscall to |
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255 | provide zero-copy operation. For this to work, $out_fh should |
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256 | refer to a socket, and $in_fh should refer to mmap'able file. |
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257 | |
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258 | If the native sendfile call fails or is not implemented, it will |
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259 | be emulated, so you can call "aio_sendfile" on any type of |
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260 | filehandle regardless of the limitations of the operating |
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261 | system. |
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262 | |
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263 | Please note, however, that "aio_sendfile" can read more bytes |
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264 | from $in_fh than are written, and there is no way to find out |
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265 | how many bytes have been read from "aio_sendfile" alone, as |
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266 | "aio_sendfile" only provides the number of bytes written to |
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267 | $out_fh. Only if the result value equals $length one can assume |
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268 | that $length bytes have been read. |
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269 | |
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270 | aio_readahead $fh,$offset,$length, $callback->($retval) |
160 | aio_readahead $fh,$offset,$length, $callback->($retval) |
271 | "aio_readahead" populates the page cache with data from a file |
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272 | so that subsequent reads from that file will not block on disk |
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273 | I/O. The $offset argument specifies the starting point from |
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274 | which data is to be read and $length specifies the number of |
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275 | bytes to be read. I/O is performed in whole pages, so that |
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276 | offset is effectively rounded down to a page boundary and bytes |
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277 | are read up to the next page boundary greater than or equal to |
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278 | (off-set+length). "aio_readahead" does not read beyond the end |
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279 | of the file. The current file offset of the file is left |
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280 | unchanged. |
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281 | |
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282 | If that syscall doesn't exist (likely if your OS isn't Linux) it |
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283 | will be emulated by simply reading the data, which would have a |
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284 | similar effect. |
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285 | |
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286 | aio_stat $fh_or_path, $callback->($status) |
161 | aio_stat $fh_or_path, $callback->($status) |
287 | aio_lstat $fh, $callback->($status) |
162 | aio_lstat $fh, $callback->($status) |
288 | Works like perl's "stat" or "lstat" in void context. The |
163 | aio_statvfs $fh_or_path, $callback->($statvfs) |
289 | callback will be called after the stat and the results will be |
164 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
290 | available using "stat _" or "-s _" etc... |
165 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
291 | |
166 | aio_truncate $fh_or_path, $offset, $callback->($status) |
292 | The pathname passed to "aio_stat" must be absolute. See API |
167 | aio_chmod $fh_or_path, $mode, $callback->($status) |
293 | NOTES, above, for an explanation. |
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294 | |
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295 | Currently, the stats are always 64-bit-stats, i.e. instead of |
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296 | returning an error when stat'ing a large file, the results will |
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297 | be silently truncated unless perl itself is compiled with large |
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298 | file support. |
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299 | |
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300 | Example: Print the length of /etc/passwd: |
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301 | |
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302 | aio_stat "/etc/passwd", sub { |
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303 | $_[0] and die "stat failed: $!"; |
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304 | print "size is ", -s _, "\n"; |
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305 | }; |
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306 | |
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307 | aio_unlink $pathname, $callback->($status) |
168 | aio_unlink $pathname, $callback->($status) |
308 | Asynchronously unlink (delete) a file and call the callback with |
169 | aio_mknod $path, $mode, $dev, $callback->($status) |
309 | the result code. |
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310 | |
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311 | aio_link $srcpath, $dstpath, $callback->($status) |
170 | aio_link $srcpath, $dstpath, $callback->($status) |
312 | Asynchronously create a new link to the existing object at |
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313 | $srcpath at the path $dstpath and call the callback with the |
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314 | result code. |
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315 | |
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316 | aio_symlink $srcpath, $dstpath, $callback->($status) |
171 | aio_symlink $srcpath, $dstpath, $callback->($status) |
317 | Asynchronously create a new symbolic link to the existing object |
172 | aio_readlink $path, $callback->($link) |
318 | at $srcpath at the path $dstpath and call the callback with the |
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319 | result code. |
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320 | |
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321 | aio_rename $srcpath, $dstpath, $callback->($status) |
173 | aio_rename $srcpath, $dstpath, $callback->($status) |
322 | Asynchronously rename the object at $srcpath to $dstpath, just |
174 | aio_mkdir $pathname, $mode, $callback->($status) |
323 | as rename(2) and call the callback with the result code. |
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324 | |
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325 | aio_rmdir $pathname, $callback->($status) |
175 | aio_rmdir $pathname, $callback->($status) |
326 | Asynchronously rmdir (delete) a directory and call the callback |
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327 | with the result code. |
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328 | |
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329 | aio_readdir $pathname, $callback->($entries) |
176 | aio_readdir $pathname, $callback->($entries) |
330 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
177 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
331 | entire directory (i.e. opendir + readdir + closedir). The |
178 | IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST |
332 | entries will not be sorted, and will NOT include the "." and |
179 | IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN |
333 | ".." entries. |
180 | aio_load $path, $data, $callback->($status) |
334 | |
181 | aio_copy $srcpath, $dstpath, $callback->($status) |
335 | The callback a single argument which is either "undef" or an |
182 | aio_move $srcpath, $dstpath, $callback->($status) |
336 | array-ref with the filenames. |
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337 | |
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338 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
183 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
339 | Scans a directory (similar to "aio_readdir") but additionally |
184 | aio_rmtree $path, $callback->($status) |
340 | tries to efficiently separate the entries of directory $path |
185 | aio_sync $callback->($status) |
341 | into two sets of names, directories you can recurse into |
|
|
342 | (directories), and ones you cannot recurse into (everything |
|
|
343 | else, including symlinks to directories). |
|
|
344 | |
|
|
345 | "aio_scandir" is a composite request that creates of many sub |
|
|
346 | requests_ $maxreq specifies the maximum number of outstanding |
|
|
347 | aio requests that this function generates. If it is "<= 0", then |
|
|
348 | a suitable default will be chosen (currently 6). |
|
|
349 | |
|
|
350 | On error, the callback is called without arguments, otherwise it |
|
|
351 | receives two array-refs with path-relative entry names. |
|
|
352 | |
|
|
353 | Example: |
|
|
354 | |
|
|
355 | aio_scandir $dir, 0, sub { |
|
|
356 | my ($dirs, $nondirs) = @_; |
|
|
357 | print "real directories: @$dirs\n"; |
|
|
358 | print "everything else: @$nondirs\n"; |
|
|
359 | }; |
|
|
360 | |
|
|
361 | Implementation notes. |
|
|
362 | |
|
|
363 | The "aio_readdir" cannot be avoided, but "stat()"'ing every |
|
|
364 | entry can. |
|
|
365 | |
|
|
366 | After reading the directory, the modification time, size etc. of |
|
|
367 | the directory before and after the readdir is checked, and if |
|
|
368 | they match (and isn't the current time), the link count will be |
|
|
369 | used to decide how many entries are directories (if >= 2). |
|
|
370 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
371 | assumed. |
|
|
372 | |
|
|
373 | Then entries will be sorted into likely directories (everything |
|
|
374 | without a non-initial dot currently) and likely non-directories |
|
|
375 | (everything else). Then every entry plus an appended "/." will |
|
|
376 | be "stat"'ed, likely directories first. If that succeeds, it |
|
|
377 | assumes that the entry is a directory or a symlink to directory |
|
|
378 | (which will be checked seperately). This is often faster than |
|
|
379 | stat'ing the entry itself because filesystems might detect the |
|
|
380 | type of the entry without reading the inode data (e.g. ext2fs |
|
|
381 | filetype feature). |
|
|
382 | |
|
|
383 | If the known number of directories (link count - 2) has been |
|
|
384 | reached, the rest of the entries is assumed to be |
|
|
385 | non-directories. |
|
|
386 | |
|
|
387 | This only works with certainty on POSIX (= UNIX) filesystems, |
|
|
388 | which fortunately are the vast majority of filesystems around. |
|
|
389 | |
|
|
390 | It will also likely work on non-POSIX filesystems with reduced |
|
|
391 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
392 | disables the directory counting heuristic. |
|
|
393 | |
|
|
394 | aio_fsync $fh, $callback->($status) |
186 | aio_fsync $fh, $callback->($status) |
395 | Asynchronously call fsync on the given filehandle and call the |
|
|
396 | callback with the fsync result code. |
|
|
397 | |
|
|
398 | aio_fdatasync $fh, $callback->($status) |
187 | aio_fdatasync $fh, $callback->($status) |
399 | Asynchronously call fdatasync on the given filehandle and call |
188 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
400 | the callback with the fdatasync result code. |
189 | aio_pathsync $path, $callback->($status) |
401 | |
190 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
402 | If this call isn't available because your OS lacks it or it |
191 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
403 | couldn't be detected, it will be emulated by calling "fsync" |
192 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
404 | instead. |
193 | aio_mlockall $flags, $callback->($status) |
405 | |
|
|
406 | aio_group $callback->(...) |
194 | aio_group $callback->(...) |
407 | This is a very special aio request: Instead of doing something, |
|
|
408 | it is a container for other aio requests, which is useful if you |
|
|
409 | want to bundle many requests into a single, composite, request |
|
|
410 | with a definite callback and the ability to cancel the whole |
|
|
411 | request with its subrequests. |
|
|
412 | |
|
|
413 | Returns an object of class IO::AIO::GRP. See its documentation |
|
|
414 | below for more info. |
|
|
415 | |
|
|
416 | Example: |
|
|
417 | |
|
|
418 | my $grp = aio_group sub { |
|
|
419 | print "all stats done\n"; |
|
|
420 | }; |
|
|
421 | |
|
|
422 | add $grp |
|
|
423 | (aio_stat ...), |
|
|
424 | (aio_stat ...), |
|
|
425 | ...; |
|
|
426 | |
|
|
427 | aio_nop $callback->() |
195 | aio_nop $callback->() |
428 | This is a special request - it does nothing in itself and is |
|
|
429 | only used for side effects, such as when you want to add a dummy |
|
|
430 | request to a group so that finishing the requests in the group |
|
|
431 | depends on executing the given code. |
|
|
432 | |
196 | |
433 | While this request does nothing, it still goes through the |
197 | $prev_pri = aioreq_pri [$pri] |
434 | execution phase and still requires a worker thread. Thus, the |
198 | aioreq_nice $pri_adjust |
435 | callback will not be executed immediately but only after other |
|
|
436 | requests in the queue have entered their execution phase. This |
|
|
437 | can be used to measure request latency. |
|
|
438 | |
199 | |
439 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
200 | IO::AIO::poll_wait |
440 | Mainly used for debugging and benchmarking, this aio request |
201 | IO::AIO::poll_cb |
441 | puts one of the request workers to sleep for the given time. |
202 | IO::AIO::poll |
|
|
203 | IO::AIO::flush |
|
|
204 | IO::AIO::max_poll_reqs $nreqs |
|
|
205 | IO::AIO::max_poll_time $seconds |
|
|
206 | IO::AIO::min_parallel $nthreads |
|
|
207 | IO::AIO::max_parallel $nthreads |
|
|
208 | IO::AIO::max_idle $nthreads |
|
|
209 | IO::AIO::max_outstanding $maxreqs |
|
|
210 | IO::AIO::nreqs |
|
|
211 | IO::AIO::nready |
|
|
212 | IO::AIO::npending |
442 | |
213 | |
443 | While it is theoretically handy to have simple I/O scheduling |
214 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
444 | requests like sleep and file handle readable/writable, the |
215 | IO::AIO::fadvise $fh, $offset, $len, $advice |
445 | overhead this creates is immense (it blocks a thread for a long |
216 | IO::AIO::madvise $scalar, $offset, $length, $advice |
446 | time) so do not use this function except to put your application |
217 | IO::AIO::mprotect $scalar, $offset, $length, $protect |
447 | under artificial I/O pressure. |
218 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
|
|
219 | IO::AIO::munlockall |
448 | |
220 | |
449 | IO::AIO::REQ CLASS |
221 | AIO REQUEST FUNCTIONS |
450 | All non-aggregate "aio_*" functions return an object of this class |
222 | All the "aio_*" calls are more or less thin wrappers around the syscall |
451 | when called in non-void context. |
223 | with the same name (sans "aio_"). The arguments are similar or |
|
|
224 | identical, and they all accept an additional (and optional) $callback |
|
|
225 | argument which must be a code reference. This code reference will get |
|
|
226 | called with the syscall return code (e.g. most syscalls return -1 on |
|
|
227 | error, unlike perl, which usually delivers "false") as its sole argument |
|
|
228 | after the given syscall has been executed asynchronously. |
452 | |
229 | |
453 | cancel $req |
230 | All functions expecting a filehandle keep a copy of the filehandle |
454 | Cancels the request, if possible. Has the effect of skipping |
231 | internally until the request has finished. |
455 | execution when entering the execute state and skipping calling |
|
|
456 | the callback when entering the the result state, but will leave |
|
|
457 | the request otherwise untouched. That means that requests that |
|
|
458 | currently execute will not be stopped and resources held by the |
|
|
459 | request will not be freed prematurely. |
|
|
460 | |
232 | |
461 | cb $req $callback->(...) |
233 | All functions return request objects of type IO::AIO::REQ that allow |
462 | Replace (or simply set) the callback registered to the request. |
234 | further manipulation of those requests while they are in-flight. |
463 | |
235 | |
464 | IO::AIO::GRP CLASS |
236 | The pathnames you pass to these routines *must* be absolute and encoded |
465 | This class is a subclass of IO::AIO::REQ, so all its methods apply |
237 | as octets. The reason for the former is that at the time the request is |
466 | to objects of this class, too. |
238 | being executed, the current working directory could have changed. |
|
|
239 | Alternatively, you can make sure that you never change the current |
|
|
240 | working directory anywhere in the program and then use relative paths. |
467 | |
241 | |
468 | A IO::AIO::GRP object is a special request that can contain multiple |
242 | To encode pathnames as octets, either make sure you either: a) always |
469 | other aio requests. |
243 | pass in filenames you got from outside (command line, readdir etc.) |
|
|
244 | without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module |
|
|
245 | and encode your pathnames to the locale (or other) encoding in effect in |
|
|
246 | the user environment, d) use Glib::filename_from_unicode on unicode |
|
|
247 | filenames or e) use something else to ensure your scalar has the correct |
|
|
248 | contents. |
470 | |
249 | |
471 | You create one by calling the "aio_group" constructing function with |
250 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
472 | a callback that will be called when all contained requests have |
251 | handles correctly whether it is set or not. |
473 | entered the "done" state: |
|
|
474 | |
252 | |
475 | my $grp = aio_group sub { |
253 | $prev_pri = aioreq_pri [$pri] |
476 | print "all requests are done\n"; |
254 | Returns the priority value that would be used for the next request |
477 | }; |
255 | and, if $pri is given, sets the priority for the next aio request. |
478 | |
256 | |
479 | You add requests by calling the "add" method with one or more |
257 | The default priority is 0, the minimum and maximum priorities are -4 |
480 | "IO::AIO::REQ" objects: |
258 | and 4, respectively. Requests with higher priority will be serviced |
|
|
259 | first. |
481 | |
260 | |
482 | $grp->add (aio_unlink "..."); |
261 | The priority will be reset to 0 after each call to one of the |
|
|
262 | "aio_*" functions. |
483 | |
263 | |
484 | add $grp aio_stat "...", sub { |
264 | Example: open a file with low priority, then read something from it |
485 | $_[0] or return $grp->result ("error"); |
265 | with higher priority so the read request is serviced before other |
|
|
266 | low priority open requests (potentially spamming the cache): |
486 | |
267 | |
487 | # add another request dynamically, if first succeeded |
268 | aioreq_pri -3; |
488 | add $grp aio_open "...", sub { |
269 | aio_open ..., sub { |
489 | $grp->result ("ok"); |
270 | return unless $_[0]; |
|
|
271 | |
|
|
272 | aioreq_pri -2; |
|
|
273 | aio_read $_[0], ..., sub { |
|
|
274 | ... |
490 | }; |
275 | }; |
491 | }; |
276 | }; |
492 | |
277 | |
|
|
278 | aioreq_nice $pri_adjust |
|
|
279 | Similar to "aioreq_pri", but subtracts the given value from the |
|
|
280 | current priority, so the effect is cumulative. |
|
|
281 | |
|
|
282 | aio_open $pathname, $flags, $mode, $callback->($fh) |
|
|
283 | Asynchronously open or create a file and call the callback with a |
|
|
284 | newly created filehandle for the file. |
|
|
285 | |
|
|
286 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
|
|
287 | above, for an explanation. |
|
|
288 | |
|
|
289 | The $flags argument is a bitmask. See the "Fcntl" module for a list. |
|
|
290 | They are the same as used by "sysopen". |
|
|
291 | |
|
|
292 | Likewise, $mode specifies the mode of the newly created file, if it |
|
|
293 | didn't exist and "O_CREAT" has been given, just like perl's |
|
|
294 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
|
|
295 | create new files, and 0666 or 0777 if you do). Note that the $mode |
|
|
296 | will be modified by the umask in effect then the request is being |
|
|
297 | executed, so better never change the umask. |
|
|
298 | |
|
|
299 | Example: |
|
|
300 | |
|
|
301 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
|
|
302 | if ($_[0]) { |
|
|
303 | print "open successful, fh is $_[0]\n"; |
|
|
304 | ... |
|
|
305 | } else { |
|
|
306 | die "open failed: $!\n"; |
|
|
307 | } |
|
|
308 | }; |
|
|
309 | |
|
|
310 | aio_close $fh, $callback->($status) |
|
|
311 | Asynchronously close a file and call the callback with the result |
|
|
312 | code. |
|
|
313 | |
|
|
314 | Unfortunately, you can't do this to perl. Perl *insists* very |
|
|
315 | strongly on closing the file descriptor associated with the |
|
|
316 | filehandle itself. |
|
|
317 | |
|
|
318 | Therefore, "aio_close" will not close the filehandle - instead it |
|
|
319 | will use dup2 to overwrite the file descriptor with the write-end of |
|
|
320 | a pipe (the pipe fd will be created on demand and will be cached). |
|
|
321 | |
|
|
322 | Or in other words: the file descriptor will be closed, but it will |
|
|
323 | not be free for reuse until the perl filehandle is closed. |
|
|
324 | |
|
|
325 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
|
|
326 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
|
|
327 | Reads or writes $length bytes from or to the specified $fh and |
|
|
328 | $offset into the scalar given by $data and offset $dataoffset and |
|
|
329 | calls the callback without the actual number of bytes read (or -1 on |
|
|
330 | error, just like the syscall). |
|
|
331 | |
|
|
332 | "aio_read" will, like "sysread", shrink or grow the $data scalar to |
|
|
333 | offset plus the actual number of bytes read. |
|
|
334 | |
|
|
335 | If $offset is undefined, then the current file descriptor offset |
|
|
336 | will be used (and updated), otherwise the file descriptor offset |
|
|
337 | will not be changed by these calls. |
|
|
338 | |
|
|
339 | If $length is undefined in "aio_write", use the remaining length of |
|
|
340 | $data. |
|
|
341 | |
|
|
342 | If $dataoffset is less than zero, it will be counted from the end of |
|
|
343 | $data. |
|
|
344 | |
|
|
345 | The $data scalar *MUST NOT* be modified in any way while the request |
|
|
346 | is outstanding. Modifying it can result in segfaults or World War |
|
|
347 | III (if the necessary/optional hardware is installed). |
|
|
348 | |
|
|
349 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
|
|
350 | offset 0 within the scalar: |
|
|
351 | |
|
|
352 | aio_read $fh, 7, 15, $buffer, 0, sub { |
|
|
353 | $_[0] > 0 or die "read error: $!"; |
|
|
354 | print "read $_[0] bytes: <$buffer>\n"; |
|
|
355 | }; |
|
|
356 | |
|
|
357 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
|
|
358 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
|
|
359 | reading at byte offset $in_offset, and starts writing at the current |
|
|
360 | file offset of $out_fh. Because of that, it is not safe to issue |
|
|
361 | more than one "aio_sendfile" per $out_fh, as they will interfere |
|
|
362 | with each other. |
|
|
363 | |
|
|
364 | This call tries to make use of a native "sendfile" syscall to |
|
|
365 | provide zero-copy operation. For this to work, $out_fh should refer |
|
|
366 | to a socket, and $in_fh should refer to an mmap'able file. |
|
|
367 | |
|
|
368 | If a native sendfile cannot be found or it fails with "ENOSYS", |
|
|
369 | "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", |
|
|
370 | it will be emulated, so you can call "aio_sendfile" on any type of |
|
|
371 | filehandle regardless of the limitations of the operating system. |
|
|
372 | |
|
|
373 | Please note, however, that "aio_sendfile" can read more bytes from |
|
|
374 | $in_fh than are written, and there is no way to find out how many |
|
|
375 | bytes have been read from "aio_sendfile" alone, as "aio_sendfile" |
|
|
376 | only provides the number of bytes written to $out_fh. Only if the |
|
|
377 | result value equals $length one can assume that $length bytes have |
|
|
378 | been read. |
|
|
379 | |
|
|
380 | aio_readahead $fh,$offset,$length, $callback->($retval) |
|
|
381 | "aio_readahead" populates the page cache with data from a file so |
|
|
382 | that subsequent reads from that file will not block on disk I/O. The |
|
|
383 | $offset argument specifies the starting point from which data is to |
|
|
384 | be read and $length specifies the number of bytes to be read. I/O is |
|
|
385 | performed in whole pages, so that offset is effectively rounded down |
|
|
386 | to a page boundary and bytes are read up to the next page boundary |
|
|
387 | greater than or equal to (off-set+length). "aio_readahead" does not |
|
|
388 | read beyond the end of the file. The current file offset of the file |
|
|
389 | is left unchanged. |
|
|
390 | |
|
|
391 | If that syscall doesn't exist (likely if your OS isn't Linux) it |
|
|
392 | will be emulated by simply reading the data, which would have a |
|
|
393 | similar effect. |
|
|
394 | |
|
|
395 | aio_stat $fh_or_path, $callback->($status) |
|
|
396 | aio_lstat $fh, $callback->($status) |
|
|
397 | Works like perl's "stat" or "lstat" in void context. The callback |
|
|
398 | will be called after the stat and the results will be available |
|
|
399 | using "stat _" or "-s _" etc... |
|
|
400 | |
|
|
401 | The pathname passed to "aio_stat" must be absolute. See API NOTES, |
|
|
402 | above, for an explanation. |
|
|
403 | |
|
|
404 | Currently, the stats are always 64-bit-stats, i.e. instead of |
|
|
405 | returning an error when stat'ing a large file, the results will be |
|
|
406 | silently truncated unless perl itself is compiled with large file |
|
|
407 | support. |
|
|
408 | |
|
|
409 | Example: Print the length of /etc/passwd: |
|
|
410 | |
|
|
411 | aio_stat "/etc/passwd", sub { |
|
|
412 | $_[0] and die "stat failed: $!"; |
|
|
413 | print "size is ", -s _, "\n"; |
|
|
414 | }; |
|
|
415 | |
|
|
416 | aio_statvfs $fh_or_path, $callback->($statvfs) |
|
|
417 | Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on |
|
|
418 | whether a file handle or path was passed. |
|
|
419 | |
|
|
420 | On success, the callback is passed a hash reference with the |
|
|
421 | following members: "bsize", "frsize", "blocks", "bfree", "bavail", |
|
|
422 | "files", "ffree", "favail", "fsid", "flag" and "namemax". On |
|
|
423 | failure, "undef" is passed. |
|
|
424 | |
|
|
425 | The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY" |
|
|
426 | and "ST_NOSUID". |
|
|
427 | |
|
|
428 | The following non-POSIX IO::AIO::ST_* flag masks are defined to |
|
|
429 | their correct value when available, or to 0 on systems that do not |
|
|
430 | support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS", |
|
|
431 | "ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE", |
|
|
432 | "ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME". |
|
|
433 | |
|
|
434 | Example: stat "/wd" and dump out the data if successful. |
|
|
435 | |
|
|
436 | aio_statvfs "/wd", sub { |
|
|
437 | my $f = $_[0] |
|
|
438 | or die "statvfs: $!"; |
|
|
439 | |
|
|
440 | use Data::Dumper; |
|
|
441 | say Dumper $f; |
|
|
442 | }; |
|
|
443 | |
|
|
444 | # result: |
|
|
445 | { |
|
|
446 | bsize => 1024, |
|
|
447 | bfree => 4333064312, |
|
|
448 | blocks => 10253828096, |
|
|
449 | files => 2050765568, |
|
|
450 | flag => 4096, |
|
|
451 | favail => 2042092649, |
|
|
452 | bavail => 4333064312, |
|
|
453 | ffree => 2042092649, |
|
|
454 | namemax => 255, |
|
|
455 | frsize => 1024, |
|
|
456 | fsid => 1810 |
|
|
457 | } |
|
|
458 | |
|
|
459 | aio_utime $fh_or_path, $atime, $mtime, $callback->($status) |
|
|
460 | Works like perl's "utime" function (including the special case of |
|
|
461 | $atime and $mtime being undef). Fractional times are supported if |
|
|
462 | the underlying syscalls support them. |
|
|
463 | |
|
|
464 | When called with a pathname, uses utimes(2) if available, otherwise |
|
|
465 | utime(2). If called on a file descriptor, uses futimes(2) if |
|
|
466 | available, otherwise returns ENOSYS, so this is not portable. |
|
|
467 | |
|
|
468 | Examples: |
|
|
469 | |
|
|
470 | # set atime and mtime to current time (basically touch(1)): |
|
|
471 | aio_utime "path", undef, undef; |
|
|
472 | # set atime to current time and mtime to beginning of the epoch: |
|
|
473 | aio_utime "path", time, undef; # undef==0 |
|
|
474 | |
|
|
475 | aio_chown $fh_or_path, $uid, $gid, $callback->($status) |
|
|
476 | Works like perl's "chown" function, except that "undef" for either |
|
|
477 | $uid or $gid is being interpreted as "do not change" (but -1 can |
|
|
478 | also be used). |
|
|
479 | |
|
|
480 | Examples: |
|
|
481 | |
|
|
482 | # same as "chown root path" in the shell: |
|
|
483 | aio_chown "path", 0, -1; |
|
|
484 | # same as above: |
|
|
485 | aio_chown "path", 0, undef; |
|
|
486 | |
|
|
487 | aio_truncate $fh_or_path, $offset, $callback->($status) |
|
|
488 | Works like truncate(2) or ftruncate(2). |
|
|
489 | |
|
|
490 | aio_chmod $fh_or_path, $mode, $callback->($status) |
|
|
491 | Works like perl's "chmod" function. |
|
|
492 | |
|
|
493 | aio_unlink $pathname, $callback->($status) |
|
|
494 | Asynchronously unlink (delete) a file and call the callback with the |
|
|
495 | result code. |
|
|
496 | |
|
|
497 | aio_mknod $path, $mode, $dev, $callback->($status) |
|
|
498 | [EXPERIMENTAL] |
|
|
499 | |
|
|
500 | Asynchronously create a device node (or fifo). See mknod(2). |
|
|
501 | |
|
|
502 | The only (POSIX-) portable way of calling this function is: |
|
|
503 | |
|
|
504 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
|
|
505 | |
|
|
506 | aio_link $srcpath, $dstpath, $callback->($status) |
|
|
507 | Asynchronously create a new link to the existing object at $srcpath |
|
|
508 | at the path $dstpath and call the callback with the result code. |
|
|
509 | |
|
|
510 | aio_symlink $srcpath, $dstpath, $callback->($status) |
|
|
511 | Asynchronously create a new symbolic link to the existing object at |
|
|
512 | $srcpath at the path $dstpath and call the callback with the result |
|
|
513 | code. |
|
|
514 | |
|
|
515 | aio_readlink $path, $callback->($link) |
|
|
516 | Asynchronously read the symlink specified by $path and pass it to |
|
|
517 | the callback. If an error occurs, nothing or undef gets passed to |
|
|
518 | the callback. |
|
|
519 | |
|
|
520 | aio_rename $srcpath, $dstpath, $callback->($status) |
|
|
521 | Asynchronously rename the object at $srcpath to $dstpath, just as |
|
|
522 | rename(2) and call the callback with the result code. |
|
|
523 | |
|
|
524 | aio_mkdir $pathname, $mode, $callback->($status) |
|
|
525 | Asynchronously mkdir (create) a directory and call the callback with |
|
|
526 | the result code. $mode will be modified by the umask at the time the |
|
|
527 | request is executed, so do not change your umask. |
|
|
528 | |
|
|
529 | aio_rmdir $pathname, $callback->($status) |
|
|
530 | Asynchronously rmdir (delete) a directory and call the callback with |
|
|
531 | the result code. |
|
|
532 | |
|
|
533 | aio_readdir $pathname, $callback->($entries) |
|
|
534 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
|
|
535 | entire directory (i.e. opendir + readdir + closedir). The entries |
|
|
536 | will not be sorted, and will NOT include the "." and ".." entries. |
|
|
537 | |
|
|
538 | The callback is passed a single argument which is either "undef" or |
|
|
539 | an array-ref with the filenames. |
|
|
540 | |
|
|
541 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
|
|
542 | Quite similar to "aio_readdir", but the $flags argument allows to |
|
|
543 | tune behaviour and output format. In case of an error, $entries will |
|
|
544 | be "undef". |
|
|
545 | |
|
|
546 | The flags are a combination of the following constants, ORed |
|
|
547 | together (the flags will also be passed to the callback, possibly |
|
|
548 | modified): |
|
|
549 | |
|
|
550 | IO::AIO::READDIR_DENTS |
|
|
551 | When this flag is off, then the callback gets an arrayref with |
|
|
552 | of names only (as with "aio_readdir"), otherwise it gets an |
|
|
553 | arrayref with "[$name, $type, $inode]" arrayrefs, each |
|
|
554 | describing a single directory entry in more detail. |
|
|
555 | |
|
|
556 | $name is the name of the entry. |
|
|
557 | |
|
|
558 | $type is one of the "IO::AIO::DT_xxx" constants: |
|
|
559 | |
|
|
560 | "IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR", |
|
|
561 | "IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG", |
|
|
562 | "IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT". |
|
|
563 | |
|
|
564 | "IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If |
|
|
565 | you need to know, you have to run stat yourself. Also, for speed |
|
|
566 | reasons, the $type scalars are read-only: you can not modify |
|
|
567 | them. |
|
|
568 | |
|
|
569 | $inode is the inode number (which might not be exact on systems |
|
|
570 | with 64 bit inode numbers and 32 bit perls). This field has |
|
|
571 | unspecified content on systems that do not deliver the inode |
|
|
572 | information. |
|
|
573 | |
|
|
574 | IO::AIO::READDIR_DIRS_FIRST |
|
|
575 | When this flag is set, then the names will be returned in an |
|
|
576 | order where likely directories come first. This is useful when |
|
|
577 | you need to quickly find directories, or you want to find all |
|
|
578 | directories while avoiding to stat() each entry. |
|
|
579 | |
|
|
580 | If the system returns type information in readdir, then this is |
|
|
581 | used to find directories directly. Otherwise, likely directories |
|
|
582 | are files beginning with ".", or otherwise files with no dots, |
|
|
583 | of which files with short names are tried first. |
|
|
584 | |
|
|
585 | IO::AIO::READDIR_STAT_ORDER |
|
|
586 | When this flag is set, then the names will be returned in an |
|
|
587 | order suitable for stat()'ing each one. That is, when you plan |
|
|
588 | to stat() all files in the given directory, then the returned |
|
|
589 | order will likely be fastest. |
|
|
590 | |
|
|
591 | If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are |
|
|
592 | specified, then the likely dirs come first, resulting in a less |
|
|
593 | optimal stat order. |
|
|
594 | |
|
|
595 | IO::AIO::READDIR_FOUND_UNKNOWN |
|
|
596 | This flag should not be set when calling "aio_readdirx". |
|
|
597 | Instead, it is being set by "aio_readdirx", when any of the |
|
|
598 | $type's found were "IO::AIO::DT_UNKNOWN". The absense of this |
|
|
599 | flag therefore indicates that all $type's are known, which can |
|
|
600 | be used to speed up some algorithms. |
|
|
601 | |
|
|
602 | aio_load $path, $data, $callback->($status) |
|
|
603 | This is a composite request that tries to fully load the given file |
|
|
604 | into memory. Status is the same as with aio_read. |
|
|
605 | |
|
|
606 | aio_copy $srcpath, $dstpath, $callback->($status) |
|
|
607 | Try to copy the *file* (directories not supported as either source |
|
|
608 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
609 | a status of 0 (ok) or -1 (error, see $!). |
|
|
610 | |
|
|
611 | This is a composite request that creates the destination file with |
|
|
612 | mode 0200 and copies the contents of the source file into it using |
|
|
613 | "aio_sendfile", followed by restoring atime, mtime, access mode and |
|
|
614 | uid/gid, in that order. |
|
|
615 | |
|
|
616 | If an error occurs, the partial destination file will be unlinked, |
|
|
617 | if possible, except when setting atime, mtime, access mode and |
|
|
618 | uid/gid, where errors are being ignored. |
|
|
619 | |
|
|
620 | aio_move $srcpath, $dstpath, $callback->($status) |
|
|
621 | Try to move the *file* (directories not supported as either source |
|
|
622 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
623 | a status of 0 (ok) or -1 (error, see $!). |
|
|
624 | |
|
|
625 | This is a composite request that tries to rename(2) the file first; |
|
|
626 | if rename fails with "EXDEV", it copies the file with "aio_copy" |
|
|
627 | and, if that is successful, unlinks the $srcpath. |
|
|
628 | |
|
|
629 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
|
|
630 | Scans a directory (similar to "aio_readdir") but additionally tries |
|
|
631 | to efficiently separate the entries of directory $path into two sets |
|
|
632 | of names, directories you can recurse into (directories), and ones |
|
|
633 | you cannot recurse into (everything else, including symlinks to |
|
|
634 | directories). |
|
|
635 | |
|
|
636 | "aio_scandir" is a composite request that creates of many sub |
|
|
637 | requests_ $maxreq specifies the maximum number of outstanding aio |
|
|
638 | requests that this function generates. If it is "<= 0", then a |
|
|
639 | suitable default will be chosen (currently 4). |
|
|
640 | |
|
|
641 | On error, the callback is called without arguments, otherwise it |
|
|
642 | receives two array-refs with path-relative entry names. |
|
|
643 | |
|
|
644 | Example: |
|
|
645 | |
|
|
646 | aio_scandir $dir, 0, sub { |
|
|
647 | my ($dirs, $nondirs) = @_; |
|
|
648 | print "real directories: @$dirs\n"; |
|
|
649 | print "everything else: @$nondirs\n"; |
|
|
650 | }; |
|
|
651 | |
|
|
652 | Implementation notes. |
|
|
653 | |
|
|
654 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
|
|
655 | can. |
|
|
656 | |
|
|
657 | If readdir returns file type information, then this is used directly |
|
|
658 | to find directories. |
|
|
659 | |
|
|
660 | Otherwise, after reading the directory, the modification time, size |
|
|
661 | etc. of the directory before and after the readdir is checked, and |
|
|
662 | if they match (and isn't the current time), the link count will be |
|
|
663 | used to decide how many entries are directories (if >= 2). |
|
|
664 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
665 | assumed. |
|
|
666 | |
|
|
667 | Then entries will be sorted into likely directories a non-initial |
|
|
668 | dot currently) and likely non-directories (see "aio_readdirx"). Then |
|
|
669 | every entry plus an appended "/." will be "stat"'ed, likely |
|
|
670 | directories first, in order of their inode numbers. If that |
|
|
671 | succeeds, it assumes that the entry is a directory or a symlink to |
|
|
672 | directory (which will be checked seperately). This is often faster |
|
|
673 | than stat'ing the entry itself because filesystems might detect the |
|
|
674 | type of the entry without reading the inode data (e.g. ext2fs |
|
|
675 | filetype feature), even on systems that cannot return the filetype |
|
|
676 | information on readdir. |
|
|
677 | |
|
|
678 | If the known number of directories (link count - 2) has been |
|
|
679 | reached, the rest of the entries is assumed to be non-directories. |
|
|
680 | |
|
|
681 | This only works with certainty on POSIX (= UNIX) filesystems, which |
|
|
682 | fortunately are the vast majority of filesystems around. |
|
|
683 | |
|
|
684 | It will also likely work on non-POSIX filesystems with reduced |
|
|
685 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
686 | disables the directory counting heuristic. |
|
|
687 | |
|
|
688 | aio_rmtree $path, $callback->($status) |
|
|
689 | Delete a directory tree starting (and including) $path, return the |
|
|
690 | status of the final "rmdir" only. This is a composite request that |
|
|
691 | uses "aio_scandir" to recurse into and rmdir directories, and unlink |
|
|
692 | everything else. |
|
|
693 | |
|
|
694 | aio_sync $callback->($status) |
|
|
695 | Asynchronously call sync and call the callback when finished. |
|
|
696 | |
|
|
697 | aio_fsync $fh, $callback->($status) |
|
|
698 | Asynchronously call fsync on the given filehandle and call the |
|
|
699 | callback with the fsync result code. |
|
|
700 | |
|
|
701 | aio_fdatasync $fh, $callback->($status) |
|
|
702 | Asynchronously call fdatasync on the given filehandle and call the |
|
|
703 | callback with the fdatasync result code. |
|
|
704 | |
|
|
705 | If this call isn't available because your OS lacks it or it couldn't |
|
|
706 | be detected, it will be emulated by calling "fsync" instead. |
|
|
707 | |
|
|
708 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
|
|
709 | Sync the data portion of the file specified by $offset and $length |
|
|
710 | to disk (but NOT the metadata), by calling the Linux-specific |
|
|
711 | sync_file_range call. If sync_file_range is not available or it |
|
|
712 | returns ENOSYS, then fdatasync or fsync is being substituted. |
|
|
713 | |
|
|
714 | $flags can be a combination of |
|
|
715 | "IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE", |
|
|
716 | "IO::AIO::SYNC_FILE_RANGE_WRITE" and |
|
|
717 | "IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range |
|
|
718 | manpage for details. |
|
|
719 | |
|
|
720 | aio_pathsync $path, $callback->($status) |
|
|
721 | This request tries to open, fsync and close the given path. This is |
|
|
722 | a composite request intended to sync directories after directory |
|
|
723 | operations (E.g. rename). This might not work on all operating |
|
|
724 | systems or have any specific effect, but usually it makes sure that |
|
|
725 | directory changes get written to disc. It works for anything that |
|
|
726 | can be opened for read-only, not just directories. |
|
|
727 | |
|
|
728 | Future versions of this function might fall back to other methods |
|
|
729 | when "fsync" on the directory fails (such as calling "sync"). |
|
|
730 | |
|
|
731 | Passes 0 when everything went ok, and -1 on error. |
|
|
732 | |
|
|
733 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
734 | $callback->($status) |
|
|
735 | This is a rather advanced IO::AIO call, which only works on |
|
|
736 | mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it |
|
|
737 | also works on data scalars managed by the Sys::Mmap or Mmap modules, |
|
|
738 | note that the scalar must only be modified in-place while an aio |
|
|
739 | operation is pending on it). |
|
|
740 | |
|
|
741 | It calls the "msync" function of your OS, if available, with the |
|
|
742 | memory area starting at $offset in the string and ending $length |
|
|
743 | bytes later. If $length is negative, counts from the end, and if |
|
|
744 | $length is "undef", then it goes till the end of the string. The |
|
|
745 | flags can be a combination of "IO::AIO::MS_ASYNC", |
|
|
746 | "IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC". |
|
|
747 | |
|
|
748 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, |
|
|
749 | $callback->($status) |
|
|
750 | This is a rather advanced IO::AIO call, which works best on |
|
|
751 | mmap(2)ed scalars. |
|
|
752 | |
|
|
753 | It touches (reads or writes) all memory pages in the specified range |
|
|
754 | inside the scalar. All caveats and parameters are the same as for |
|
|
755 | "aio_msync", above, except for flags, which must be either 0 (which |
|
|
756 | reads all pages and ensures they are instantiated) or |
|
|
757 | "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading |
|
|
758 | and writing an octet from it, which dirties the page). |
|
|
759 | |
|
|
760 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
|
|
761 | This is a rather advanced IO::AIO call, which works best on |
|
|
762 | mmap(2)ed scalars. |
|
|
763 | |
|
|
764 | It reads in all the pages of the underlying storage into memory (if |
|
|
765 | any) and locks them, so they are not getting swapped/paged out or |
|
|
766 | removed. |
|
|
767 | |
|
|
768 | If $length is undefined, then the scalar will be locked till the |
|
|
769 | end. |
|
|
770 | |
|
|
771 | On systems that do not implement "mlock", this function returns -1 |
|
|
772 | and sets errno to "ENOSYS". |
|
|
773 | |
|
|
774 | Note that the corresponding "munlock" is synchronous and is |
|
|
775 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
776 | |
|
|
777 | Example: open a file, mmap and mlock it - both will be undone when |
|
|
778 | $data gets destroyed. |
|
|
779 | |
|
|
780 | open my $fh, "<", $path or die "$path: $!"; |
|
|
781 | my $data; |
|
|
782 | IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
|
|
783 | aio_mlock $data; # mlock in background |
|
|
784 | |
|
|
785 | aio_mlockall $flags, $callback->($status) |
|
|
786 | Calls the "mlockall" function with the given $flags (a combination |
|
|
787 | of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). |
|
|
788 | |
|
|
789 | On systems that do not implement "mlockall", this function returns |
|
|
790 | -1 and sets errno to "ENOSYS". |
|
|
791 | |
|
|
792 | Note that the corresponding "munlockall" is synchronous and is |
|
|
793 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
794 | |
|
|
795 | Example: asynchronously lock all current and future pages into |
|
|
796 | memory. |
|
|
797 | |
|
|
798 | aio_mlockall IO::AIO::MCL_FUTURE; |
|
|
799 | |
|
|
800 | aio_group $callback->(...) |
|
|
801 | This is a very special aio request: Instead of doing something, it |
|
|
802 | is a container for other aio requests, which is useful if you want |
|
|
803 | to bundle many requests into a single, composite, request with a |
|
|
804 | definite callback and the ability to cancel the whole request with |
|
|
805 | its subrequests. |
|
|
806 | |
|
|
807 | Returns an object of class IO::AIO::GRP. See its documentation below |
|
|
808 | for more info. |
|
|
809 | |
|
|
810 | Example: |
|
|
811 | |
|
|
812 | my $grp = aio_group sub { |
|
|
813 | print "all stats done\n"; |
|
|
814 | }; |
|
|
815 | |
|
|
816 | add $grp |
|
|
817 | (aio_stat ...), |
|
|
818 | (aio_stat ...), |
|
|
819 | ...; |
|
|
820 | |
|
|
821 | aio_nop $callback->() |
|
|
822 | This is a special request - it does nothing in itself and is only |
|
|
823 | used for side effects, such as when you want to add a dummy request |
|
|
824 | to a group so that finishing the requests in the group depends on |
|
|
825 | executing the given code. |
|
|
826 | |
|
|
827 | While this request does nothing, it still goes through the execution |
|
|
828 | phase and still requires a worker thread. Thus, the callback will |
|
|
829 | not be executed immediately but only after other requests in the |
|
|
830 | queue have entered their execution phase. This can be used to |
|
|
831 | measure request latency. |
|
|
832 | |
|
|
833 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
|
|
834 | Mainly used for debugging and benchmarking, this aio request puts |
|
|
835 | one of the request workers to sleep for the given time. |
|
|
836 | |
|
|
837 | While it is theoretically handy to have simple I/O scheduling |
|
|
838 | requests like sleep and file handle readable/writable, the overhead |
|
|
839 | this creates is immense (it blocks a thread for a long time) so do |
|
|
840 | not use this function except to put your application under |
|
|
841 | artificial I/O pressure. |
|
|
842 | |
|
|
843 | IO::AIO::REQ CLASS |
|
|
844 | All non-aggregate "aio_*" functions return an object of this class when |
|
|
845 | called in non-void context. |
|
|
846 | |
|
|
847 | cancel $req |
|
|
848 | Cancels the request, if possible. Has the effect of skipping |
|
|
849 | execution when entering the execute state and skipping calling the |
|
|
850 | callback when entering the the result state, but will leave the |
|
|
851 | request otherwise untouched (with the exception of readdir). That |
|
|
852 | means that requests that currently execute will not be stopped and |
|
|
853 | resources held by the request will not be freed prematurely. |
|
|
854 | |
|
|
855 | cb $req $callback->(...) |
|
|
856 | Replace (or simply set) the callback registered to the request. |
|
|
857 | |
|
|
858 | IO::AIO::GRP CLASS |
|
|
859 | This class is a subclass of IO::AIO::REQ, so all its methods apply to |
|
|
860 | objects of this class, too. |
|
|
861 | |
|
|
862 | A IO::AIO::GRP object is a special request that can contain multiple |
|
|
863 | other aio requests. |
|
|
864 | |
|
|
865 | You create one by calling the "aio_group" constructing function with a |
|
|
866 | callback that will be called when all contained requests have entered |
|
|
867 | the "done" state: |
|
|
868 | |
|
|
869 | my $grp = aio_group sub { |
|
|
870 | print "all requests are done\n"; |
|
|
871 | }; |
|
|
872 | |
|
|
873 | You add requests by calling the "add" method with one or more |
|
|
874 | "IO::AIO::REQ" objects: |
|
|
875 | |
|
|
876 | $grp->add (aio_unlink "..."); |
|
|
877 | |
|
|
878 | add $grp aio_stat "...", sub { |
|
|
879 | $_[0] or return $grp->result ("error"); |
|
|
880 | |
|
|
881 | # add another request dynamically, if first succeeded |
|
|
882 | add $grp aio_open "...", sub { |
|
|
883 | $grp->result ("ok"); |
|
|
884 | }; |
|
|
885 | }; |
|
|
886 | |
493 | This makes it very easy to create composite requests (see the source |
887 | This makes it very easy to create composite requests (see the source of |
494 | of "aio_move" for an application) that work and feel like simple |
888 | "aio_move" for an application) that work and feel like simple requests. |
|
|
889 | |
|
|
890 | * The IO::AIO::GRP objects will be cleaned up during calls to |
|
|
891 | "IO::AIO::poll_cb", just like any other request. |
|
|
892 | |
|
|
893 | * They can be canceled like any other request. Canceling will cancel |
|
|
894 | not only the request itself, but also all requests it contains. |
|
|
895 | |
|
|
896 | * They can also can also be added to other IO::AIO::GRP objects. |
|
|
897 | |
|
|
898 | * You must not add requests to a group from within the group callback |
|
|
899 | (or any later time). |
|
|
900 | |
|
|
901 | Their lifetime, simplified, looks like this: when they are empty, they |
|
|
902 | will finish very quickly. If they contain only requests that are in the |
|
|
903 | "done" state, they will also finish. Otherwise they will continue to |
|
|
904 | exist. |
|
|
905 | |
|
|
906 | That means after creating a group you have some time to add requests |
|
|
907 | (precisely before the callback has been invoked, which is only done |
|
|
908 | within the "poll_cb"). And in the callbacks of those requests, you can |
|
|
909 | add further requests to the group. And only when all those requests have |
|
|
910 | finished will the the group itself finish. |
|
|
911 | |
|
|
912 | add $grp ... |
|
|
913 | $grp->add (...) |
|
|
914 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
|
|
915 | be added, including other groups, as long as you do not create |
|
|
916 | circular dependencies. |
|
|
917 | |
|
|
918 | Returns all its arguments. |
|
|
919 | |
|
|
920 | $grp->cancel_subs |
|
|
921 | Cancel all subrequests and clears any feeder, but not the group |
|
|
922 | request itself. Useful when you queued a lot of events but got a |
|
|
923 | result early. |
|
|
924 | |
|
|
925 | The group request will finish normally (you cannot add requests to |
|
|
926 | the group). |
|
|
927 | |
|
|
928 | $grp->result (...) |
|
|
929 | Set the result value(s) that will be passed to the group callback |
|
|
930 | when all subrequests have finished and set the groups errno to the |
|
|
931 | current value of errno (just like calling "errno" without an error |
|
|
932 | number). By default, no argument will be passed and errno is zero. |
|
|
933 | |
|
|
934 | $grp->errno ([$errno]) |
|
|
935 | Sets the group errno value to $errno, or the current value of errno |
|
|
936 | when the argument is missing. |
|
|
937 | |
|
|
938 | Every aio request has an associated errno value that is restored |
|
|
939 | when the callback is invoked. This method lets you change this value |
|
|
940 | from its default (0). |
|
|
941 | |
|
|
942 | Calling "result" will also set errno, so make sure you either set $! |
|
|
943 | before the call to "result", or call c<errno> after it. |
|
|
944 | |
|
|
945 | feed $grp $callback->($grp) |
|
|
946 | Sets a feeder/generator on this group: every group can have an |
|
|
947 | attached generator that generates requests if idle. The idea behind |
|
|
948 | this is that, although you could just queue as many requests as you |
|
|
949 | want in a group, this might starve other requests for a potentially |
|
|
950 | long time. For example, "aio_scandir" might generate hundreds of |
|
|
951 | thousands "aio_stat" requests, delaying any later requests for a |
|
|
952 | long time. |
|
|
953 | |
|
|
954 | To avoid this, and allow incremental generation of requests, you can |
|
|
955 | instead a group and set a feeder on it that generates those |
|
|
956 | requests. The feed callback will be called whenever there are few |
|
|
957 | enough (see "limit", below) requests active in the group itself and |
|
|
958 | is expected to queue more requests. |
|
|
959 | |
|
|
960 | The feed callback can queue as many requests as it likes (i.e. "add" |
|
|
961 | does not impose any limits). |
|
|
962 | |
|
|
963 | If the feed does not queue more requests when called, it will be |
|
|
964 | automatically removed from the group. |
|
|
965 | |
|
|
966 | If the feed limit is 0 when this method is called, it will be set to |
|
|
967 | 2 automatically. |
|
|
968 | |
|
|
969 | Example: |
|
|
970 | |
|
|
971 | # stat all files in @files, but only ever use four aio requests concurrently: |
|
|
972 | |
|
|
973 | my $grp = aio_group sub { print "finished\n" }; |
|
|
974 | limit $grp 4; |
|
|
975 | feed $grp sub { |
|
|
976 | my $file = pop @files |
|
|
977 | or return; |
|
|
978 | |
|
|
979 | add $grp aio_stat $file, sub { ... }; |
|
|
980 | }; |
|
|
981 | |
|
|
982 | limit $grp $num |
|
|
983 | Sets the feeder limit for the group: The feeder will be called |
|
|
984 | whenever the group contains less than this many requests. |
|
|
985 | |
|
|
986 | Setting the limit to 0 will pause the feeding process. |
|
|
987 | |
|
|
988 | The default value for the limit is 0, but note that setting a feeder |
|
|
989 | automatically bumps it up to 2. |
|
|
990 | |
|
|
991 | SUPPORT FUNCTIONS |
|
|
992 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
|
|
993 | $fileno = IO::AIO::poll_fileno |
|
|
994 | Return the *request result pipe file descriptor*. This filehandle |
|
|
995 | must be polled for reading by some mechanism outside this module |
|
|
996 | (e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the |
|
|
997 | pipe becomes readable you have to call "poll_cb" to check the |
|
|
998 | results. |
|
|
999 | |
|
|
1000 | See "poll_cb" for an example. |
|
|
1001 | |
|
|
1002 | IO::AIO::poll_cb |
|
|
1003 | Process some outstanding events on the result pipe. You have to call |
|
|
1004 | this regularly. Returns 0 if all events could be processed, or -1 if |
|
|
1005 | it returned earlier for whatever reason. Returns immediately when no |
|
|
1006 | events are outstanding. The amount of events processed depends on |
|
|
1007 | the settings of "IO::AIO::max_poll_req" and |
|
|
1008 | "IO::AIO::max_poll_time". |
|
|
1009 | |
|
|
1010 | If not all requests were processed for whatever reason, the |
|
|
1011 | filehandle will still be ready when "poll_cb" returns, so normally |
|
|
1012 | you don't have to do anything special to have it called later. |
|
|
1013 | |
|
|
1014 | Example: Install an Event watcher that automatically calls |
|
|
1015 | IO::AIO::poll_cb with high priority (more examples can be found in |
|
|
1016 | the SYNOPSIS section, at the top of this document): |
|
|
1017 | |
|
|
1018 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1019 | poll => 'r', async => 1, |
|
|
1020 | cb => \&IO::AIO::poll_cb); |
|
|
1021 | |
|
|
1022 | IO::AIO::poll_wait |
|
|
1023 | If there are any outstanding requests and none of them in the result |
|
|
1024 | phase, wait till the result filehandle becomes ready for reading |
|
|
1025 | (simply does a "select" on the filehandle. This is useful if you |
|
|
1026 | want to synchronously wait for some requests to finish). |
|
|
1027 | |
|
|
1028 | See "nreqs" for an example. |
|
|
1029 | |
|
|
1030 | IO::AIO::poll |
|
|
1031 | Waits until some requests have been handled. |
|
|
1032 | |
|
|
1033 | Returns the number of requests processed, but is otherwise strictly |
|
|
1034 | equivalent to: |
|
|
1035 | |
|
|
1036 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1037 | |
|
|
1038 | IO::AIO::flush |
|
|
1039 | Wait till all outstanding AIO requests have been handled. |
|
|
1040 | |
|
|
1041 | Strictly equivalent to: |
|
|
1042 | |
|
|
1043 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1044 | while IO::AIO::nreqs; |
|
|
1045 | |
|
|
1046 | IO::AIO::max_poll_reqs $nreqs |
|
|
1047 | IO::AIO::max_poll_time $seconds |
|
|
1048 | These set the maximum number of requests (default 0, meaning |
|
|
1049 | infinity) that are being processed by "IO::AIO::poll_cb" in one |
|
|
1050 | call, respectively the maximum amount of time (default 0, meaning |
|
|
1051 | infinity) spent in "IO::AIO::poll_cb" to process requests (more |
|
|
1052 | correctly the mininum amount of time "poll_cb" is allowed to use). |
|
|
1053 | |
|
|
1054 | Setting "max_poll_time" to a non-zero value creates an overhead of |
|
|
1055 | one syscall per request processed, which is not normally a problem |
|
|
1056 | unless your callbacks are really really fast or your OS is really |
|
|
1057 | really slow (I am not mentioning Solaris here). Using |
|
|
1058 | "max_poll_reqs" incurs no overhead. |
|
|
1059 | |
|
|
1060 | Setting these is useful if you want to ensure some level of |
|
|
1061 | interactiveness when perl is not fast enough to process all requests |
|
|
1062 | in time. |
|
|
1063 | |
|
|
1064 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
|
|
1065 | |
|
|
1066 | Example: Install an Event watcher that automatically calls |
|
|
1067 | IO::AIO::poll_cb with low priority, to ensure that other parts of |
|
|
1068 | the program get the CPU sometimes even under high AIO load. |
|
|
1069 | |
|
|
1070 | # try not to spend much more than 0.1s in poll_cb |
|
|
1071 | IO::AIO::max_poll_time 0.1; |
|
|
1072 | |
|
|
1073 | # use a low priority so other tasks have priority |
|
|
1074 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1075 | poll => 'r', nice => 1, |
|
|
1076 | cb => &IO::AIO::poll_cb); |
|
|
1077 | |
|
|
1078 | CONTROLLING THE NUMBER OF THREADS |
|
|
1079 | IO::AIO::min_parallel $nthreads |
|
|
1080 | Set the minimum number of AIO threads to $nthreads. The current |
|
|
1081 | default is 8, which means eight asynchronous operations can execute |
|
|
1082 | concurrently at any one time (the number of outstanding requests, |
|
|
1083 | however, is unlimited). |
|
|
1084 | |
|
|
1085 | IO::AIO starts threads only on demand, when an AIO request is queued |
|
|
1086 | and no free thread exists. Please note that queueing up a hundred |
|
|
1087 | requests can create demand for a hundred threads, even if it turns |
|
|
1088 | out that everything is in the cache and could have been processed |
|
|
1089 | faster by a single thread. |
|
|
1090 | |
|
|
1091 | It is recommended to keep the number of threads relatively low, as |
|
|
1092 | some Linux kernel versions will scale negatively with the number of |
|
|
1093 | threads (higher parallelity => MUCH higher latency). With current |
|
|
1094 | Linux 2.6 versions, 4-32 threads should be fine. |
|
|
1095 | |
|
|
1096 | Under most circumstances you don't need to call this function, as |
|
|
1097 | the module selects a default that is suitable for low to moderate |
|
|
1098 | load. |
|
|
1099 | |
|
|
1100 | IO::AIO::max_parallel $nthreads |
|
|
1101 | Sets the maximum number of AIO threads to $nthreads. If more than |
|
|
1102 | the specified number of threads are currently running, this function |
|
|
1103 | kills them. This function blocks until the limit is reached. |
|
|
1104 | |
|
|
1105 | While $nthreads are zero, aio requests get queued but not executed |
|
|
1106 | until the number of threads has been increased again. |
|
|
1107 | |
|
|
1108 | This module automatically runs "max_parallel 0" at program end, to |
|
|
1109 | ensure that all threads are killed and that there are no outstanding |
495 | requests. |
1110 | requests. |
496 | |
1111 | |
497 | * The IO::AIO::GRP objects will be cleaned up during calls to |
|
|
498 | "IO::AIO::poll_cb", just like any other request. |
|
|
499 | * They can be canceled like any other request. Canceling will cancel |
|
|
500 | not only the request itself, but also all requests it contains. |
|
|
501 | * They can also can also be added to other IO::AIO::GRP objects. |
|
|
502 | * You must not add requests to a group from within the group |
|
|
503 | callback (or any later time). |
|
|
504 | |
|
|
505 | Their lifetime, simplified, looks like this: when they are empty, |
|
|
506 | they will finish very quickly. If they contain only requests that |
|
|
507 | are in the "done" state, they will also finish. Otherwise they will |
|
|
508 | continue to exist. |
|
|
509 | |
|
|
510 | That means after creating a group you have some time to add |
|
|
511 | requests. And in the callbacks of those requests, you can add |
|
|
512 | further requests to the group. And only when all those requests have |
|
|
513 | finished will the the group itself finish. |
|
|
514 | |
|
|
515 | add $grp ... |
|
|
516 | $grp->add (...) |
|
|
517 | Add one or more requests to the group. Any type of IO::AIO::REQ |
|
|
518 | can be added, including other groups, as long as you do not |
|
|
519 | create circular dependencies. |
|
|
520 | |
|
|
521 | Returns all its arguments. |
|
|
522 | |
|
|
523 | $grp->cancel_subs |
|
|
524 | Cancel all subrequests and clears any feeder, but not the group |
|
|
525 | request itself. Useful when you queued a lot of events but got a |
|
|
526 | result early. |
|
|
527 | |
|
|
528 | $grp->result (...) |
|
|
529 | Set the result value(s) that will be passed to the group |
|
|
530 | callback when all subrequests have finished and set thre groups |
|
|
531 | errno to the current value of errno (just like calling "errno" |
|
|
532 | without an error number). By default, no argument will be passed |
|
|
533 | and errno is zero. |
|
|
534 | |
|
|
535 | $grp->errno ([$errno]) |
|
|
536 | Sets the group errno value to $errno, or the current value of |
|
|
537 | errno when the argument is missing. |
|
|
538 | |
|
|
539 | Every aio request has an associated errno value that is restored |
|
|
540 | when the callback is invoked. This method lets you change this |
|
|
541 | value from its default (0). |
|
|
542 | |
|
|
543 | Calling "result" will also set errno, so make sure you either |
|
|
544 | set $! before the call to "result", or call c<errno> after it. |
|
|
545 | |
|
|
546 | feed $grp $callback->($grp) |
|
|
547 | Sets a feeder/generator on this group: every group can have an |
|
|
548 | attached generator that generates requests if idle. The idea |
|
|
549 | behind this is that, although you could just queue as many |
|
|
550 | requests as you want in a group, this might starve other |
|
|
551 | requests for a potentially long time. For example, "aio_scandir" |
|
|
552 | might generate hundreds of thousands "aio_stat" requests, |
|
|
553 | delaying any later requests for a long time. |
|
|
554 | |
|
|
555 | To avoid this, and allow incremental generation of requests, you |
|
|
556 | can instead a group and set a feeder on it that generates those |
|
|
557 | requests. The feed callback will be called whenever there are |
|
|
558 | few enough (see "limit", below) requests active in the group |
|
|
559 | itself and is expected to queue more requests. |
|
|
560 | |
|
|
561 | The feed callback can queue as many requests as it likes (i.e. |
|
|
562 | "add" does not impose any limits). |
|
|
563 | |
|
|
564 | If the feed does not queue more requests when called, it will be |
|
|
565 | automatically removed from the group. |
|
|
566 | |
|
|
567 | If the feed limit is 0, it will be set to 2 automatically. |
|
|
568 | |
|
|
569 | Example: |
|
|
570 | |
|
|
571 | # stat all files in @files, but only ever use four aio requests concurrently: |
|
|
572 | |
|
|
573 | my $grp = aio_group sub { print "finished\n" }; |
|
|
574 | limit $grp 4; |
|
|
575 | feed $grp sub { |
|
|
576 | my $file = pop @files |
|
|
577 | or return; |
|
|
578 | |
|
|
579 | add $grp aio_stat $file, sub { ... }; |
|
|
580 | }; |
|
|
581 | |
|
|
582 | limit $grp $num |
|
|
583 | Sets the feeder limit for the group: The feeder will be called |
|
|
584 | whenever the group contains less than this many requests. |
|
|
585 | |
|
|
586 | Setting the limit to 0 will pause the feeding process. |
|
|
587 | |
|
|
588 | SUPPORT FUNCTIONS |
|
|
589 | $fileno = IO::AIO::poll_fileno |
|
|
590 | Return the *request result pipe file descriptor*. This |
|
|
591 | filehandle must be polled for reading by some mechanism outside |
|
|
592 | this module (e.g. Event or select, see below or the SYNOPSIS). |
|
|
593 | If the pipe becomes readable you have to call "poll_cb" to check |
|
|
594 | the results. |
|
|
595 | |
|
|
596 | See "poll_cb" for an example. |
|
|
597 | |
|
|
598 | IO::AIO::poll_cb |
|
|
599 | Process all outstanding events on the result pipe. You have to |
|
|
600 | call this regularly. Returns the number of events processed. |
|
|
601 | Returns immediately when no events are outstanding. |
|
|
602 | |
|
|
603 | If not all requests were processed for whatever reason, the |
|
|
604 | filehandle will still be ready when "poll_cb" returns. |
|
|
605 | |
|
|
606 | Example: Install an Event watcher that automatically calls |
|
|
607 | IO::AIO::poll_cb with high priority: |
|
|
608 | |
|
|
609 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
610 | poll => 'r', async => 1, |
|
|
611 | cb => \&IO::AIO::poll_cb); |
|
|
612 | |
|
|
613 | IO::AIO::poll_some $max_requests |
|
|
614 | Similar to "poll_cb", but only processes up to $max_requests |
|
|
615 | requests at a time. |
|
|
616 | |
|
|
617 | Useful if you want to ensure some level of interactiveness when |
|
|
618 | perl is not fast enough to process all requests in time. |
|
|
619 | |
|
|
620 | Example: Install an Event watcher that automatically calls |
|
|
621 | IO::AIO::poll_some with low priority, to ensure that other parts |
|
|
622 | of the program get the CPU sometimes even under high AIO load. |
|
|
623 | |
|
|
624 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
625 | poll => 'r', nice => 1, |
|
|
626 | cb => sub { IO::AIO::poll_some 256 }); |
|
|
627 | |
|
|
628 | IO::AIO::poll_wait |
|
|
629 | Wait till the result filehandle becomes ready for reading |
|
|
630 | (simply does a "select" on the filehandle. This is useful if you |
|
|
631 | want to synchronously wait for some requests to finish). |
|
|
632 | |
|
|
633 | See "nreqs" for an example. |
|
|
634 | |
|
|
635 | IO::AIO::nreqs |
|
|
636 | Returns the number of requests currently in the ready, execute |
|
|
637 | or pending states (i.e. for which their callback has not been |
|
|
638 | invoked yet). |
|
|
639 | |
|
|
640 | Example: wait till there are no outstanding requests anymore: |
|
|
641 | |
|
|
642 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
643 | while IO::AIO::nreqs; |
|
|
644 | |
|
|
645 | IO::AIO::nready |
|
|
646 | Returns the number of requests currently in the ready state (not |
|
|
647 | yet executed). |
|
|
648 | |
|
|
649 | IO::AIO::npending |
|
|
650 | Returns the number of requests currently in the pending state |
|
|
651 | (executed, but not yet processed by poll_cb). |
|
|
652 | |
|
|
653 | IO::AIO::flush |
|
|
654 | Wait till all outstanding AIO requests have been handled. |
|
|
655 | |
|
|
656 | Strictly equivalent to: |
|
|
657 | |
|
|
658 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
659 | while IO::AIO::nreqs; |
|
|
660 | |
|
|
661 | IO::AIO::poll |
|
|
662 | Waits until some requests have been handled. |
|
|
663 | |
|
|
664 | Strictly equivalent to: |
|
|
665 | |
|
|
666 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
667 | if IO::AIO::nreqs; |
|
|
668 | |
|
|
669 | IO::AIO::min_parallel $nthreads |
|
|
670 | Set the minimum number of AIO threads to $nthreads. The current |
|
|
671 | default is 8, which means eight asynchronous operations can |
|
|
672 | execute concurrently at any one time (the number of outstanding |
|
|
673 | requests, however, is unlimited). |
|
|
674 | |
|
|
675 | IO::AIO starts threads only on demand, when an AIO request is |
|
|
676 | queued and no free thread exists. |
|
|
677 | |
|
|
678 | It is recommended to keep the number of threads relatively low, |
|
|
679 | as some Linux kernel versions will scale negatively with the |
|
|
680 | number of threads (higher parallelity => MUCH higher latency). |
|
|
681 | With current Linux 2.6 versions, 4-32 threads should be fine. |
|
|
682 | |
|
|
683 | Under most circumstances you don't need to call this function, |
|
|
684 | as the module selects a default that is suitable for low to |
|
|
685 | moderate load. |
|
|
686 | |
|
|
687 | IO::AIO::max_parallel $nthreads |
|
|
688 | Sets the maximum number of AIO threads to $nthreads. If more |
|
|
689 | than the specified number of threads are currently running, this |
|
|
690 | function kills them. This function blocks until the limit is |
|
|
691 | reached. |
|
|
692 | |
|
|
693 | While $nthreads are zero, aio requests get queued but not |
|
|
694 | executed until the number of threads has been increased again. |
|
|
695 | |
|
|
696 | This module automatically runs "max_parallel 0" at program end, |
|
|
697 | to ensure that all threads are killed and that there are no |
|
|
698 | outstanding requests. |
|
|
699 | |
|
|
700 | Under normal circumstances you don't need to call this function. |
1112 | Under normal circumstances you don't need to call this function. |
701 | |
1113 | |
|
|
1114 | IO::AIO::max_idle $nthreads |
|
|
1115 | Limit the number of threads (default: 4) that are allowed to idle |
|
|
1116 | (i.e., threads that did not get a request to process within 10 |
|
|
1117 | seconds). That means if a thread becomes idle while $nthreads other |
|
|
1118 | threads are also idle, it will free its resources and exit. |
|
|
1119 | |
|
|
1120 | This is useful when you allow a large number of threads (e.g. 100 or |
|
|
1121 | 1000) to allow for extremely high load situations, but want to free |
|
|
1122 | resources under normal circumstances (1000 threads can easily |
|
|
1123 | consume 30MB of RAM). |
|
|
1124 | |
|
|
1125 | The default is probably ok in most situations, especially if thread |
|
|
1126 | creation is fast. If thread creation is very slow on your system you |
|
|
1127 | might want to use larger values. |
|
|
1128 | |
702 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
1129 | IO::AIO::max_outstanding $maxreqs |
703 | This is a very bad function to use in interactive programs |
1130 | This is a very bad function to use in interactive programs because |
704 | because it blocks, and a bad way to reduce concurrency because |
1131 | it blocks, and a bad way to reduce concurrency because it is |
705 | it is inexact: Better use an "aio_group" together with a feed |
1132 | inexact: Better use an "aio_group" together with a feed callback. |
706 | callback. |
|
|
707 | |
1133 | |
708 | Sets the maximum number of outstanding requests to $nreqs. If |
1134 | Sets the maximum number of outstanding requests to $nreqs. If you do |
709 | you to queue up more than this number of requests, the next call |
1135 | queue up more than this number of requests, the next call to the |
710 | to the "poll_cb" (and "poll_some" and other functions calling |
1136 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
711 | "poll_cb") function will block until the limit is no longer |
1137 | function will block until the limit is no longer exceeded. |
712 | exceeded. |
|
|
713 | |
1138 | |
714 | The default value is very large, so there is no practical limit |
1139 | The default value is very large, so there is no practical limit on |
715 | on the number of outstanding requests. |
1140 | the number of outstanding requests. |
716 | |
1141 | |
717 | You can still queue as many requests as you want. Therefore, |
1142 | You can still queue as many requests as you want. Therefore, |
718 | "max_oustsanding" is mainly useful in simple scripts (with low |
1143 | "max_outstanding" is mainly useful in simple scripts (with low |
719 | values) or as a stop gap to shield against fatal memory overflow |
1144 | values) or as a stop gap to shield against fatal memory overflow |
720 | (with large values). |
1145 | (with large values). |
|
|
1146 | |
|
|
1147 | STATISTICAL INFORMATION |
|
|
1148 | IO::AIO::nreqs |
|
|
1149 | Returns the number of requests currently in the ready, execute or |
|
|
1150 | pending states (i.e. for which their callback has not been invoked |
|
|
1151 | yet). |
|
|
1152 | |
|
|
1153 | Example: wait till there are no outstanding requests anymore: |
|
|
1154 | |
|
|
1155 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
|
1156 | while IO::AIO::nreqs; |
|
|
1157 | |
|
|
1158 | IO::AIO::nready |
|
|
1159 | Returns the number of requests currently in the ready state (not yet |
|
|
1160 | executed). |
|
|
1161 | |
|
|
1162 | IO::AIO::npending |
|
|
1163 | Returns the number of requests currently in the pending state |
|
|
1164 | (executed, but not yet processed by poll_cb). |
|
|
1165 | |
|
|
1166 | MISCELLANEOUS FUNCTIONS |
|
|
1167 | IO::AIO implements some functions that might be useful, but are not |
|
|
1168 | asynchronous. |
|
|
1169 | |
|
|
1170 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
|
|
1171 | Calls the "eio_sendfile_sync" function, which is like |
|
|
1172 | "aio_sendfile", but is blocking (this makes most sense if you know |
|
|
1173 | the input data is likely cached already and the output filehandle is |
|
|
1174 | set to non-blocking operations). |
|
|
1175 | |
|
|
1176 | Returns the number of bytes copied, or -1 on error. |
|
|
1177 | |
|
|
1178 | IO::AIO::fadvise $fh, $offset, $len, $advice |
|
|
1179 | Simply calls the "posix_fadvise" function (see its manpage for |
|
|
1180 | details). The following advice constants are avaiable: |
|
|
1181 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
|
|
1182 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
|
|
1183 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
|
|
1184 | |
|
|
1185 | On systems that do not implement "posix_fadvise", this function |
|
|
1186 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
|
|
1187 | |
|
|
1188 | IO::AIO::madvise $scalar, $offset, $len, $advice |
|
|
1189 | Simply calls the "posix_madvise" function (see its manpage for |
|
|
1190 | details). The following advice constants are avaiable: |
|
|
1191 | "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", |
|
|
1192 | "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", |
|
|
1193 | "IO::AIO::MADV_DONTNEED". |
|
|
1194 | |
|
|
1195 | On systems that do not implement "posix_madvise", this function |
|
|
1196 | returns ENOSYS, otherwise the return value of "posix_madvise". |
|
|
1197 | |
|
|
1198 | IO::AIO::mprotect $scalar, $offset, $len, $protect |
|
|
1199 | Simply calls the "mprotect" function on the preferably AIO::mmap'ed |
|
|
1200 | $scalar (see its manpage for details). The following protect |
|
|
1201 | constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", |
|
|
1202 | "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". |
|
|
1203 | |
|
|
1204 | On systems that do not implement "mprotect", this function returns |
|
|
1205 | ENOSYS, otherwise the return value of "mprotect". |
|
|
1206 | |
|
|
1207 | IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
|
|
1208 | Memory-maps a file (or anonymous memory range) and attaches it to |
|
|
1209 | the given $scalar, which will act like a string scalar. |
|
|
1210 | |
|
|
1211 | The only operations allowed on the scalar are "substr"/"vec" that |
|
|
1212 | don't change the string length, and most read-only operations such |
|
|
1213 | as copying it or searching it with regexes and so on. |
|
|
1214 | |
|
|
1215 | Anything else is unsafe and will, at best, result in memory leaks. |
|
|
1216 | |
|
|
1217 | The memory map associated with the $scalar is automatically removed |
|
|
1218 | when the $scalar is destroyed, or when the "IO::AIO::mmap" or |
|
|
1219 | "IO::AIO::munmap" functions are called. |
|
|
1220 | |
|
|
1221 | This calls the "mmap"(2) function internally. See your system's |
|
|
1222 | manual page for details on the $length, $prot and $flags parameters. |
|
|
1223 | |
|
|
1224 | The $length must be larger than zero and smaller than the actual |
|
|
1225 | filesize. |
|
|
1226 | |
|
|
1227 | $prot is a combination of "IO::AIO::PROT_NONE", |
|
|
1228 | "IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or |
|
|
1229 | "IO::AIO::PROT_WRITE", |
|
|
1230 | |
|
|
1231 | $flags can be a combination of "IO::AIO::MAP_SHARED" or |
|
|
1232 | "IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when |
|
|
1233 | not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS" |
|
|
1234 | (which is set to "MAP_ANON" if your system only provides this |
|
|
1235 | constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED", |
|
|
1236 | "IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or |
|
|
1237 | "IO::AIO::MAP_NONBLOCK" |
|
|
1238 | |
|
|
1239 | If $fh is "undef", then a file descriptor of -1 is passed. |
|
|
1240 | |
|
|
1241 | $offset is the offset from the start of the file - it generally must |
|
|
1242 | be a multiple of "IO::AIO::PAGESIZE" and defaults to 0. |
|
|
1243 | |
|
|
1244 | Example: |
|
|
1245 | |
|
|
1246 | use Digest::MD5; |
|
|
1247 | use IO::AIO; |
|
|
1248 | |
|
|
1249 | open my $fh, "<verybigfile" |
|
|
1250 | or die "$!"; |
|
|
1251 | |
|
|
1252 | IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh |
|
|
1253 | or die "verybigfile: $!"; |
|
|
1254 | |
|
|
1255 | my $fast_md5 = md5 $data; |
|
|
1256 | |
|
|
1257 | IO::AIO::munmap $scalar |
|
|
1258 | Removes a previous mmap and undefines the $scalar. |
|
|
1259 | |
|
|
1260 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
|
|
1261 | Calls the "munlock" function, undoing the effects of a previous |
|
|
1262 | "aio_mlock" call (see its description for details). |
|
|
1263 | |
|
|
1264 | IO::AIO::munlockall |
|
|
1265 | Calls the "munlockall" function. |
|
|
1266 | |
|
|
1267 | On systems that do not implement "munlockall", this function returns |
|
|
1268 | ENOSYS, otherwise the return value of "munlockall". |
|
|
1269 | |
|
|
1270 | EVENT LOOP INTEGRATION |
|
|
1271 | It is recommended to use AnyEvent::AIO to integrate IO::AIO |
|
|
1272 | automatically into many event loops: |
|
|
1273 | |
|
|
1274 | # AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...) |
|
|
1275 | use AnyEvent::AIO; |
|
|
1276 | |
|
|
1277 | You can also integrate IO::AIO manually into many event loops, here are |
|
|
1278 | some examples of how to do this: |
|
|
1279 | |
|
|
1280 | # EV integration |
|
|
1281 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
|
|
1282 | |
|
|
1283 | # Event integration |
|
|
1284 | Event->io (fd => IO::AIO::poll_fileno, |
|
|
1285 | poll => 'r', |
|
|
1286 | cb => \&IO::AIO::poll_cb); |
|
|
1287 | |
|
|
1288 | # Glib/Gtk2 integration |
|
|
1289 | add_watch Glib::IO IO::AIO::poll_fileno, |
|
|
1290 | in => sub { IO::AIO::poll_cb; 1 }; |
|
|
1291 | |
|
|
1292 | # Tk integration |
|
|
1293 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
|
|
1294 | readable => \&IO::AIO::poll_cb); |
|
|
1295 | |
|
|
1296 | # Danga::Socket integration |
|
|
1297 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
|
|
1298 | \&IO::AIO::poll_cb); |
721 | |
1299 | |
722 | FORK BEHAVIOUR |
1300 | FORK BEHAVIOUR |
723 | This module should do "the right thing" when the process using it |
1301 | This module should do "the right thing" when the process using it forks: |
724 | forks: |
|
|
725 | |
1302 | |
726 | Before the fork, IO::AIO enters a quiescent state where no requests |
1303 | Before the fork, IO::AIO enters a quiescent state where no requests can |
727 | can be added in other threads and no results will be processed. |
1304 | be added in other threads and no results will be processed. After the |
728 | After the fork the parent simply leaves the quiescent state and |
1305 | fork the parent simply leaves the quiescent state and continues |
729 | continues request/result processing, while the child frees the |
1306 | request/result processing, while the child frees the request/result |
730 | request/result queue (so that the requests started before the fork |
1307 | queue (so that the requests started before the fork will only be handled |
731 | will only be handled in the parent). Threads will be started on |
1308 | in the parent). Threads will be started on demand until the limit set in |
732 | demand until the limit set in the parent process has been reached |
1309 | the parent process has been reached again. |
733 | again. |
|
|
734 | |
1310 | |
735 | In short: the parent will, after a short pause, continue as if fork |
1311 | In short: the parent will, after a short pause, continue as if fork had |
736 | had not been called, while the child will act as if IO::AIO has not |
1312 | not been called, while the child will act as if IO::AIO has not been |
737 | been used yet. |
1313 | used yet. |
738 | |
1314 | |
739 | MEMORY USAGE |
1315 | MEMORY USAGE |
740 | Per-request usage: |
1316 | Per-request usage: |
741 | |
1317 | |
742 | Each aio request uses - depending on your architecture - around |
1318 | Each aio request uses - depending on your architecture - around 100-200 |
743 | 100-200 bytes of memory. In addition, stat requests need a stat |
1319 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
744 | buffer (possibly a few hundred bytes), readdir requires a result |
1320 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
745 | buffer and so on. Perl scalars and other data passed into aio |
1321 | scalars and other data passed into aio requests will also be locked and |
746 | requests will also be locked and will consume memory till the |
1322 | will consume memory till the request has entered the done state. |
747 | request has entered the done state. |
|
|
748 | |
1323 | |
749 | This is now awfully much, so queuing lots of requests is not usually |
1324 | This is not awfully much, so queuing lots of requests is not usually a |
750 | a problem. |
1325 | problem. |
751 | |
1326 | |
752 | Per-thread usage: |
1327 | Per-thread usage: |
753 | |
1328 | |
754 | In the execution phase, some aio requests require more memory for |
1329 | In the execution phase, some aio requests require more memory for |
755 | temporary buffers, and each thread requires a stack and other data |
1330 | temporary buffers, and each thread requires a stack and other data |
756 | structures (usually around 16k-128k, depending on the OS). |
1331 | structures (usually around 16k-128k, depending on the OS). |
757 | |
1332 | |
758 | KNOWN BUGS |
1333 | KNOWN BUGS |
759 | Known bugs will be fixed in the next release. |
1334 | Known bugs will be fixed in the next release. |
760 | |
1335 | |
761 | SEE ALSO |
1336 | SEE ALSO |
762 | Coro::AIO. |
1337 | AnyEvent::AIO for easy integration into event loops, Coro::AIO for a |
|
|
1338 | more natural syntax. |
763 | |
1339 | |
764 | AUTHOR |
1340 | AUTHOR |
765 | Marc Lehmann <schmorp@schmorp.de> |
1341 | Marc Lehmann <schmorp@schmorp.de> |
766 | http://home.schmorp.de/ |
1342 | http://home.schmorp.de/ |
767 | |
1343 | |