… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | use IO::AIO; |
7 | use IO::AIO; |
8 | |
8 | |
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9 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
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10 | my ($fh) = @_; |
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11 | ... |
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12 | }; |
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13 | |
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14 | aio_unlink "/tmp/file", sub { }; |
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15 | |
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16 | aio_read $fh, 30000, 1024, $buffer, 0, sub { |
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17 | $_[0] > 0 or die "read error: $!"; |
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18 | }; |
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19 | |
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20 | # Event |
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21 | Event->io (fd => IO::AIO::poll_fileno, |
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22 | poll => 'r', |
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23 | cb => \&IO::AIO::poll_cb); |
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24 | |
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25 | # Glib/Gtk2 |
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26 | add_watch Glib::IO IO::AIO::poll_fileno, |
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27 | in => sub { IO::AIO::poll_cb; 1 }; |
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28 | |
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29 | # Tk |
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30 | Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "", |
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31 | readable => \&IO::AIO::poll_cb); |
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32 | |
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33 | # Danga::Socket |
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34 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
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35 | \&IO::AIO::poll_cb); |
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36 | |
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37 | |
9 | =head1 DESCRIPTION |
38 | =head1 DESCRIPTION |
10 | |
39 | |
11 | This module implements asynchronous I/O using whatever means your |
40 | This module implements asynchronous I/O using whatever means your |
12 | operating system supports. Currently, it falls back to Linux::AIO if that |
41 | operating system supports. |
13 | module is available, or uses pthreads to emulato aio functionality. |
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14 | |
42 | |
15 | Currently, in this module a number of threads are started that execute |
43 | Currently, a number of threads are started that execute your read/writes |
16 | your read/writes and signal their completion. You don't need thread |
44 | and signal their completion. You don't need thread support in your libc or |
17 | support in your libc or perl, and the threads created by this module will |
45 | perl, and the threads created by this module will not be visible to the |
18 | not be visible to the pthreads library. |
46 | pthreads library. In the future, this module might make use of the native |
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47 | aio functions available on many operating systems. However, they are often |
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48 | not well-supported (Linux doesn't allow them on normal files currently, |
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49 | for example), and they would only support aio_read and aio_write, so the |
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50 | remaining functionality would have to be implemented using threads anyway. |
19 | |
51 | |
20 | Although the module will work with in the presence of other threads, it is |
52 | Although the module will work with in the presence of other threads, it is |
21 | not reentrant, so use appropriate locking yourself. |
53 | currently not reentrant, so use appropriate locking yourself, always call |
22 | |
54 | C<poll_cb> from within the same thread, or never call C<poll_cb> (or other |
23 | =head2 API NOTES |
55 | C<aio_> functions) recursively. |
24 | |
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25 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
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26 | with the same name (sans C<aio_>). The arguments are similar or identical, |
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27 | and they all accept an additional C<$callback> argument which must be |
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28 | a code reference. This code reference will get called with the syscall |
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29 | return code (e.g. most syscalls return C<-1> on error, unlike perl, which |
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30 | usually delivers "false") as it's sole argument when the given syscall has |
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31 | been executed asynchronously. |
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32 | |
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33 | All functions that expect a filehandle will also accept a file descriptor. |
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34 | |
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35 | The filenames you pass to these routines I<must> be absolute. The reason |
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36 | is that at the time the request is being executed, the current working |
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37 | directory could have changed. Alternatively, you can make sure that you |
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38 | never change the current working directory. |
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39 | |
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40 | =over 4 |
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41 | |
56 | |
42 | =cut |
57 | =cut |
43 | |
58 | |
44 | package IO::AIO; |
59 | package IO::AIO; |
45 | |
60 | |
46 | use base 'Exporter'; |
61 | use base 'Exporter'; |
47 | |
62 | |
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63 | use Fcntl (); |
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64 | |
48 | BEGIN { |
65 | BEGIN { |
49 | $VERSION = 0.1; |
66 | $VERSION = 0.9; |
50 | |
67 | |
51 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
68 | @EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink |
52 | aio_fsync aio_fdatasync aio_readahead); |
69 | aio_fsync aio_fdatasync aio_readahead); |
53 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs); |
70 | @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs); |
54 | |
71 | |
55 | require XSLoader; |
72 | require XSLoader; |
56 | XSLoader::load IO::AIO, $VERSION; |
73 | XSLoader::load IO::AIO, $VERSION; |
57 | } |
74 | } |
58 | |
75 | |
59 | =item IO::AIO::min_parallel $nthreads |
76 | =head1 FUNCTIONS |
60 | |
77 | |
61 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
78 | =head2 AIO FUNCTIONS |
62 | C<1>, which means a single asynchronous operation can be done at one time |
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63 | (the number of outstanding operations, however, is unlimited). |
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64 | |
79 | |
65 | It is recommended to keep the number of threads low, as some linux |
80 | All the C<aio_*> calls are more or less thin wrappers around the syscall |
66 | kernel versions will scale negatively with the number of threads (higher |
81 | with the same name (sans C<aio_>). The arguments are similar or identical, |
67 | parallelity => MUCH higher latency). |
82 | and they all accept an additional (and optional) C<$callback> argument |
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83 | which must be a code reference. This code reference will get called with |
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84 | the syscall return code (e.g. most syscalls return C<-1> on error, unlike |
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85 | perl, which usually delivers "false") as it's sole argument when the given |
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86 | syscall has been executed asynchronously. |
68 | |
87 | |
69 | Under normal circumstances you don't need to call this function, as this |
88 | All functions that expect a filehandle will also accept a file descriptor. |
70 | module automatically starts a single async thread. |
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71 | |
89 | |
72 | =item IO::AIO::max_parallel $nthreads |
90 | The filenames you pass to these routines I<must> be absolute. The reason |
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91 | for this is that at the time the request is being executed, the current |
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92 | working directory could have changed. Alternatively, you can make sure |
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93 | that you never change the current working directory. |
73 | |
94 | |
74 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
95 | =over 4 |
75 | the specified number of threads are currently running, kill them. This |
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76 | function blocks until the limit is reached. |
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77 | |
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78 | This module automatically runs C<max_parallel 0> at program end, to ensure |
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79 | that all threads are killed and that there are no outstanding requests. |
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80 | |
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81 | Under normal circumstances you don't need to call this function. |
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82 | |
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83 | =item $fileno = IO::AIO::poll_fileno |
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84 | |
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85 | Return the I<request result pipe filehandle>. This filehandle must be |
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86 | polled for reading by some mechanism outside this module (e.g. Event |
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87 | or select, see below). If the pipe becomes readable you have to call |
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88 | C<poll_cb> to check the results. |
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89 | |
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90 | See C<poll_cb> for an example. |
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91 | |
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92 | =item IO::AIO::poll_cb |
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93 | |
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94 | Process all outstanding events on the result pipe. You have to call this |
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95 | regularly. Returns the number of events processed. Returns immediately |
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96 | when no events are outstanding. |
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97 | |
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98 | You can use Event to multiplex, e.g.: |
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99 | |
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100 | Event->io (fd => IO::AIO::poll_fileno, |
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101 | poll => 'r', async => 1, |
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102 | cb => \&IO::AIO::poll_cb); |
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103 | |
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104 | =item IO::AIO::poll_wait |
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105 | |
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106 | Wait till the result filehandle becomes ready for reading (simply does a |
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107 | select on the filehandle. This is useful if you want to synchronously wait |
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108 | for some requests to finish). |
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109 | |
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110 | See C<nreqs> for an example. |
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111 | |
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112 | =item IO::AIO::nreqs |
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113 | |
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114 | Returns the number of requests currently outstanding. |
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115 | |
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116 | Example: wait till there are no outstanding requests anymore: |
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117 | |
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118 | IO::AIO::poll_wait, IO::AIO::poll_cb |
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119 | while IO::AIO::nreqs; |
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120 | |
96 | |
121 | =item aio_open $pathname, $flags, $mode, $callback |
97 | =item aio_open $pathname, $flags, $mode, $callback |
122 | |
98 | |
123 | Asynchronously open or create a file and call the callback with the |
99 | Asynchronously open or create a file and call the callback with a newly |
124 | filedescriptor (NOT a perl filehandle, sorry for that, but watch out, this |
100 | created filehandle for the file. |
125 | might change in the future). |
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126 | |
101 | |
127 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
102 | The pathname passed to C<aio_open> must be absolute. See API NOTES, above, |
128 | for an explanation. |
103 | for an explanation. |
129 | |
104 | |
130 | The C<$mode> argument is a bitmask. See the C<Fcntl> module for a |
105 | The C<$flags> argument is a bitmask. See the C<Fcntl> module for a |
131 | list. They are the same as used in C<sysopen>. |
106 | list. They are the same as used by C<sysopen>. |
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107 | |
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108 | Likewise, C<$mode> specifies the mode of the newly created file, if it |
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109 | didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>, |
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110 | except that it is mandatory (i.e. use C<0> if you don't create new files, |
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111 | and C<0666> or C<0777> if you do). |
132 | |
112 | |
133 | Example: |
113 | Example: |
134 | |
114 | |
135 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
115 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
136 | if ($_[0] >= 0) { |
116 | if ($_[0]) { |
137 | open my $fh, "<&$_[0]"; # create a copy for perl |
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138 | aio_close $_[0], sub { }; # close the aio handle |
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139 | print "open successful, fh is $fh\n"; |
117 | print "open successful, fh is $_[0]\n"; |
140 | ... |
118 | ... |
141 | } else { |
119 | } else { |
142 | die "open failed: $!\n"; |
120 | die "open failed: $!\n"; |
143 | } |
121 | } |
144 | }; |
122 | }; |
145 | |
123 | |
146 | =item aio_close $fh, $callback |
124 | =item aio_close $fh, $callback |
147 | |
125 | |
148 | Asynchronously close a file and call the callback with the result code. |
126 | Asynchronously close a file and call the callback with the result |
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127 | code. I<WARNING:> although accepted, you should not pass in a perl |
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128 | filehandle here, as perl will likely close the file descriptor another |
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129 | time when the filehandle is destroyed. Normally, you can safely call perls |
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130 | C<close> or just let filehandles go out of scope. |
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131 | |
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132 | This is supposed to be a bug in the API, so that might change. It's |
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133 | therefore best to avoid this function. |
149 | |
134 | |
150 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
135 | =item aio_read $fh,$offset,$length, $data,$dataoffset,$callback |
151 | |
136 | |
152 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
137 | =item aio_write $fh,$offset,$length, $data,$dataoffset,$callback |
153 | |
138 | |
154 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
139 | Reads or writes C<length> bytes from the specified C<fh> and C<offset> |
155 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
140 | into the scalar given by C<data> and offset C<dataoffset> and calls the |
156 | callback without the actual number of bytes read (or -1 on error, just |
141 | callback without the actual number of bytes read (or -1 on error, just |
157 | like the syscall). |
142 | like the syscall). |
158 | |
143 | |
159 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at |
144 | Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at |
160 | offset C<0> within the scalar: |
145 | offset C<0> within the scalar: |
161 | |
146 | |
162 | aio_read $fh, 7, 15, $buffer, 0, sub { |
147 | aio_read $fh, 7, 15, $buffer, 0, sub { |
163 | $_[0] >= 0 or die "read error: $!"; |
148 | $_[0] > 0 or die "read error: $!"; |
164 | print "read <$buffer>\n"; |
149 | print "read $_[0] bytes: <$buffer>\n"; |
165 | }; |
150 | }; |
166 | |
151 | |
167 | =item aio_readahead $fh,$offset,$length, $callback |
152 | =item aio_readahead $fh,$offset,$length, $callback |
168 | |
153 | |
169 | Asynchronously reads the specified byte range into the page cache, using |
154 | Asynchronously reads the specified byte range into the page cache, using |
170 | the C<readahead> syscall. If that syscall doesn't exist the status will be |
155 | the C<readahead> syscall. If that syscall doesn't exist (likely if your OS |
171 | C<-1> and C<$!> is set to ENOSYS. |
156 | isn't Linux) the status will be C<-1> and C<$!> is set to C<ENOSYS>. |
172 | |
157 | |
173 | readahead() populates the page cache with data from a file so that |
158 | C<aio_readahead> populates the page cache with data from a file so that |
174 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
159 | subsequent reads from that file will not block on disk I/O. The C<$offset> |
175 | argument specifies the starting point from which data is to be read and |
160 | argument specifies the starting point from which data is to be read and |
176 | C<$length> specifies the number of bytes to be read. I/O is performed in |
161 | C<$length> specifies the number of bytes to be read. I/O is performed in |
177 | whole pages, so that offset is effectively rounded down to a page boundary |
162 | whole pages, so that offset is effectively rounded down to a page boundary |
178 | and bytes are read up to the next page boundary greater than or equal to |
163 | and bytes are read up to the next page boundary greater than or equal to |
179 | (off-set+length). aio_readahead() does not read beyond the end of the |
164 | (off-set+length). C<aio_readahead> does not read beyond the end of the |
180 | file. The current file offset of the file is left unchanged. |
165 | file. The current file offset of the file is left unchanged. |
181 | |
166 | |
182 | =item aio_stat $fh_or_path, $callback |
167 | =item aio_stat $fh_or_path, $callback |
183 | |
168 | |
184 | =item aio_lstat $fh, $callback |
169 | =item aio_lstat $fh, $callback |
… | |
… | |
212 | with the fsync result code. |
197 | with the fsync result code. |
213 | |
198 | |
214 | =item aio_fdatasync $fh, $callback |
199 | =item aio_fdatasync $fh, $callback |
215 | |
200 | |
216 | Asynchronously call fdatasync on the given filehandle and call the |
201 | Asynchronously call fdatasync on the given filehandle and call the |
217 | callback with the fdatasync result code. |
202 | callback with the fdatasync result code. Might set C<$!> to C<ENOSYS> if |
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203 | C<fdatasync> is not available. |
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204 | |
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205 | =back |
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206 | |
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207 | =head2 SUPPORT FUNCTIONS |
|
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208 | |
|
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209 | =over 4 |
|
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210 | |
|
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211 | =item $fileno = IO::AIO::poll_fileno |
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212 | |
|
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213 | Return the I<request result pipe file descriptor>. This filehandle must be |
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214 | polled for reading by some mechanism outside this module (e.g. Event or |
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215 | select, see below or the SYNOPSIS). If the pipe becomes readable you have |
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216 | to call C<poll_cb> to check the results. |
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217 | |
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218 | See C<poll_cb> for an example. |
|
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219 | |
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220 | =item IO::AIO::poll_cb |
|
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221 | |
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222 | Process all outstanding events on the result pipe. You have to call this |
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223 | regularly. Returns the number of events processed. Returns immediately |
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224 | when no events are outstanding. |
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225 | |
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226 | Example: Install an Event watcher that automatically calls |
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227 | IO::AIO::poll_cb with high priority: |
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228 | |
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229 | Event->io (fd => IO::AIO::poll_fileno, |
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230 | poll => 'r', async => 1, |
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231 | cb => \&IO::AIO::poll_cb); |
|
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232 | |
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233 | =item IO::AIO::poll_wait |
|
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234 | |
|
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235 | Wait till the result filehandle becomes ready for reading (simply does a |
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236 | C<select> on the filehandle. This is useful if you want to synchronously wait |
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237 | for some requests to finish). |
|
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238 | |
|
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239 | See C<nreqs> for an example. |
|
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240 | |
|
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241 | =item IO::AIO::nreqs |
|
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242 | |
|
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243 | Returns the number of requests currently outstanding (i.e. for which their |
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244 | callback has not been invoked yet). |
|
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245 | |
|
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246 | Example: wait till there are no outstanding requests anymore: |
|
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247 | |
|
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248 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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249 | while IO::AIO::nreqs; |
|
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250 | |
|
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251 | =item IO::AIO::flush |
|
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252 | |
|
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253 | Wait till all outstanding AIO requests have been handled. |
|
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254 | |
|
|
255 | Strictly equivalent to: |
|
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256 | |
|
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257 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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258 | while IO::AIO::nreqs; |
|
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259 | |
|
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260 | =item IO::AIO::poll |
|
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261 | |
|
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262 | Waits until some requests have been handled. |
|
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263 | |
|
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264 | Strictly equivalent to: |
|
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265 | |
|
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266 | IO::AIO::poll_wait, IO::AIO::poll_cb |
|
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267 | if IO::AIO::nreqs; |
|
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268 | |
|
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269 | =item IO::AIO::min_parallel $nthreads |
|
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270 | |
|
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271 | Set the minimum number of AIO threads to C<$nthreads>. The default is |
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272 | C<1>, which means a single asynchronous operation can be done at one time |
|
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273 | (the number of outstanding operations, however, is unlimited). |
|
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274 | |
|
|
275 | It is recommended to keep the number of threads low, as some Linux |
|
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276 | kernel versions will scale negatively with the number of threads (higher |
|
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277 | parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32 |
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278 | threads should be fine. |
|
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279 | |
|
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280 | Under normal circumstances you don't need to call this function, as this |
|
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281 | module automatically starts some threads (the exact number might change, |
|
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282 | and is currently 4). |
|
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283 | |
|
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284 | =item IO::AIO::max_parallel $nthreads |
|
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285 | |
|
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286 | Sets the maximum number of AIO threads to C<$nthreads>. If more than |
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287 | the specified number of threads are currently running, kill them. This |
|
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288 | function blocks until the limit is reached. |
|
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289 | |
|
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290 | This module automatically runs C<max_parallel 0> at program end, to ensure |
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291 | that all threads are killed and that there are no outstanding requests. |
|
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292 | |
|
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293 | Under normal circumstances you don't need to call this function. |
|
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294 | |
|
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295 | =item $oldnreqs = IO::AIO::max_outstanding $nreqs |
|
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296 | |
|
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297 | Sets the maximum number of outstanding requests to C<$nreqs>. If you |
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298 | try to queue up more than this number of requests, the caller will block until |
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299 | some requests have been handled. |
|
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300 | |
|
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301 | The default is very large, so normally there is no practical limit. If you |
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302 | queue up many requests in a loop it it often improves speed if you set |
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303 | this to a relatively low number, such as C<100>. |
|
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304 | |
|
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305 | Under normal circumstances you don't need to call this function. |
|
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306 | |
|
|
307 | =back |
218 | |
308 | |
219 | =cut |
309 | =cut |
|
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310 | |
|
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311 | # support function to convert a fd into a perl filehandle |
|
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312 | sub _fd2fh { |
|
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313 | return undef if $_[0] < 0; |
|
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314 | |
|
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315 | # try to be perl5.6-compatible |
|
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316 | local *AIO_FH; |
|
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317 | open AIO_FH, "+<&=$_[0]" |
|
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318 | or return undef; |
|
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319 | |
|
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320 | *AIO_FH |
|
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321 | } |
220 | |
322 | |
221 | min_parallel 4; |
323 | min_parallel 4; |
222 | |
324 | |
223 | END { |
325 | END { |
224 | max_parallel 0; |
326 | max_parallel 0; |
225 | } |
327 | } |
226 | |
328 | |
227 | 1; |
329 | 1; |
228 | |
330 | |
229 | =back |
|
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230 | |
|
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231 | =head1 BUGS |
|
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232 | |
|
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233 | - aio_open gives a fd, but all other functions expect a perl filehandle. |
|
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234 | |
|
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235 | =head1 SEE ALSO |
331 | =head1 SEE ALSO |
236 | |
332 | |
237 | L<Coro>, L<Linux::AIO>. |
333 | L<Coro>, L<Linux::AIO>. |
238 | |
334 | |
239 | =head1 AUTHOR |
335 | =head1 AUTHOR |