| … | |
… | |
| 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 = shift |
8 | my $fh = shift |
| 9 | or die "/etc/passwd: $!"; |
9 | or die "/etc/passwd: $!"; |
| 10 | ... |
10 | ... |
| 11 | }; |
11 | }; |
| 12 | |
12 | |
| … | |
… | |
| 72 | |
72 | |
| 73 | # register the IO::AIO callback with EV |
73 | # register the IO::AIO callback with EV |
| 74 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
74 | my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb; |
| 75 | |
75 | |
| 76 | # queue the request to open /etc/passwd |
76 | # queue the request to open /etc/passwd |
| 77 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
77 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
| 78 | my $fh = shift |
78 | my $fh = shift |
| 79 | or die "error while opening: $!"; |
79 | or die "error while opening: $!"; |
| 80 | |
80 | |
| 81 | # stat'ing filehandles is generally non-blocking |
81 | # stat'ing filehandles is generally non-blocking |
| 82 | my $size = -s $fh; |
82 | my $size = -s $fh; |
| … | |
… | |
| 168 | aio_unlink $pathname, $callback->($status) |
168 | aio_unlink $pathname, $callback->($status) |
| 169 | aio_mknod $path, $mode, $dev, $callback->($status) |
169 | aio_mknod $path, $mode, $dev, $callback->($status) |
| 170 | aio_link $srcpath, $dstpath, $callback->($status) |
170 | aio_link $srcpath, $dstpath, $callback->($status) |
| 171 | aio_symlink $srcpath, $dstpath, $callback->($status) |
171 | aio_symlink $srcpath, $dstpath, $callback->($status) |
| 172 | aio_readlink $path, $callback->($link) |
172 | aio_readlink $path, $callback->($link) |
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|
173 | aio_realpath $path, $callback->($link) |
| 173 | aio_rename $srcpath, $dstpath, $callback->($status) |
174 | aio_rename $srcpath, $dstpath, $callback->($status) |
| 174 | aio_mkdir $pathname, $mode, $callback->($status) |
175 | aio_mkdir $pathname, $mode, $callback->($status) |
| 175 | aio_rmdir $pathname, $callback->($status) |
176 | aio_rmdir $pathname, $callback->($status) |
| 176 | aio_readdir $pathname, $callback->($entries) |
177 | aio_readdir $pathname, $callback->($entries) |
| 177 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
178 | aio_readdirx $pathname, $flags, $callback->($entries, $flags) |
| … | |
… | |
| 187 | aio_fdatasync $fh, $callback->($status) |
188 | aio_fdatasync $fh, $callback->($status) |
| 188 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
189 | aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status) |
| 189 | aio_pathsync $path, $callback->($status) |
190 | aio_pathsync $path, $callback->($status) |
| 190 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
191 | aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
| 191 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
192 | aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status) |
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193 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
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194 | aio_mlockall $flags, $callback->($status) |
| 192 | aio_group $callback->(...) |
195 | aio_group $callback->(...) |
| 193 | aio_nop $callback->() |
196 | aio_nop $callback->() |
| 194 | |
197 | |
| 195 | $prev_pri = aioreq_pri [$pri] |
198 | $prev_pri = aioreq_pri [$pri] |
| 196 | aioreq_nice $pri_adjust |
199 | aioreq_nice $pri_adjust |
| … | |
… | |
| 202 | IO::AIO::max_poll_reqs $nreqs |
205 | IO::AIO::max_poll_reqs $nreqs |
| 203 | IO::AIO::max_poll_time $seconds |
206 | IO::AIO::max_poll_time $seconds |
| 204 | IO::AIO::min_parallel $nthreads |
207 | IO::AIO::min_parallel $nthreads |
| 205 | IO::AIO::max_parallel $nthreads |
208 | IO::AIO::max_parallel $nthreads |
| 206 | IO::AIO::max_idle $nthreads |
209 | IO::AIO::max_idle $nthreads |
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210 | IO::AIO::idle_timeout $seconds |
| 207 | IO::AIO::max_outstanding $maxreqs |
211 | IO::AIO::max_outstanding $maxreqs |
| 208 | IO::AIO::nreqs |
212 | IO::AIO::nreqs |
| 209 | IO::AIO::nready |
213 | IO::AIO::nready |
| 210 | IO::AIO::npending |
214 | IO::AIO::npending |
| 211 | |
215 | |
| 212 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
216 | IO::AIO::sendfile $ofh, $ifh, $offset, $count |
| 213 | IO::AIO::fadvise $fh, $offset, $len, $advice |
217 | IO::AIO::fadvise $fh, $offset, $len, $advice |
| 214 | IO::AIO::mlockall $flags |
218 | IO::AIO::madvise $scalar, $offset, $length, $advice |
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219 | IO::AIO::mprotect $scalar, $offset, $length, $protect |
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220 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
| 215 | IO::AIO::munlockall |
221 | IO::AIO::munlockall |
| 216 | |
222 | |
| 217 | AIO REQUEST FUNCTIONS |
223 | AIO REQUEST FUNCTIONS |
| 218 | All the "aio_*" calls are more or less thin wrappers around the syscall |
224 | All the "aio_*" calls are more or less thin wrappers around the syscall |
| 219 | with the same name (sans "aio_"). The arguments are similar or |
225 | with the same name (sans "aio_"). The arguments are similar or |
| … | |
… | |
| 292 | will be modified by the umask in effect then the request is being |
298 | will be modified by the umask in effect then the request is being |
| 293 | executed, so better never change the umask. |
299 | executed, so better never change the umask. |
| 294 | |
300 | |
| 295 | Example: |
301 | Example: |
| 296 | |
302 | |
| 297 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
303 | aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub { |
| 298 | if ($_[0]) { |
304 | if ($_[0]) { |
| 299 | print "open successful, fh is $_[0]\n"; |
305 | print "open successful, fh is $_[0]\n"; |
| 300 | ... |
306 | ... |
| 301 | } else { |
307 | } else { |
| 302 | die "open failed: $!\n"; |
308 | die "open failed: $!\n"; |
| 303 | } |
309 | } |
| 304 | }; |
310 | }; |
| 305 | |
311 | |
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312 | In addition to all the common open modes/flags ("O_RDONLY", |
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313 | "O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and |
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314 | "O_APPEND"), the following POSIX and non-POSIX constants are |
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315 | available (missing ones on your system are, as usual, 0): |
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316 | |
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317 | "O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY", |
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318 | "O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY", |
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319 | "O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT". |
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320 | |
| 306 | aio_close $fh, $callback->($status) |
321 | aio_close $fh, $callback->($status) |
| 307 | Asynchronously close a file and call the callback with the result |
322 | Asynchronously close a file and call the callback with the result |
| 308 | code. |
323 | code. |
| 309 | |
324 | |
| 310 | Unfortunately, you can't do this to perl. Perl *insists* very |
325 | Unfortunately, you can't do this to perl. Perl *insists* very |
| … | |
… | |
| 353 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
368 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
| 354 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
369 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
| 355 | reading at byte offset $in_offset, and starts writing at the current |
370 | reading at byte offset $in_offset, and starts writing at the current |
| 356 | file offset of $out_fh. Because of that, it is not safe to issue |
371 | file offset of $out_fh. Because of that, it is not safe to issue |
| 357 | more than one "aio_sendfile" per $out_fh, as they will interfere |
372 | more than one "aio_sendfile" per $out_fh, as they will interfere |
| 358 | with each other. |
373 | with each other. The same $in_fh works fine though, as this function |
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374 | does not move or use the file offset of $in_fh. |
| 359 | |
375 | |
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376 | Please note that "aio_sendfile" can read more bytes from $in_fh than |
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377 | are written, and there is no way to find out how many more bytes |
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378 | have been read from "aio_sendfile" alone, as "aio_sendfile" only |
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379 | provides the number of bytes written to $out_fh. Only if the result |
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380 | value equals $length one can assume that $length bytes have been |
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381 | read. |
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382 | |
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383 | Unlike with other "aio_" functions, it makes a lot of sense to use |
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384 | "aio_sendfile" on non-blocking sockets, as long as one end |
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385 | (typically the $in_fh) is a file - the file I/O will then be |
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386 | asynchronous, while the socket I/O will be non-blocking. Note, |
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387 | however, that you can run into a trap where "aio_sendfile" reads |
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388 | some data with readahead, then fails to write all data, and when the |
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389 | socket is ready the next time, the data in the cache is already |
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390 | lost, forcing "aio_sendfile" to again hit the disk. Explicit |
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391 | "aio_read" + "aio_write" let's you better control resource usage. |
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392 | |
| 360 | This call tries to make use of a native "sendfile" syscall to |
393 | This call tries to make use of a native "sendfile"-like syscall to |
| 361 | provide zero-copy operation. For this to work, $out_fh should refer |
394 | provide zero-copy operation. For this to work, $out_fh should refer |
| 362 | to a socket, and $in_fh should refer to an mmap'able file. |
395 | to a socket, and $in_fh should refer to an mmap'able file. |
| 363 | |
396 | |
| 364 | If a native sendfile cannot be found or it fails with "ENOSYS", |
397 | If a native sendfile cannot be found or it fails with "ENOSYS", |
| 365 | "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK", |
398 | "EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or |
| 366 | it will be emulated, so you can call "aio_sendfile" on any type of |
399 | "ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on |
| 367 | filehandle regardless of the limitations of the operating system. |
400 | any type of filehandle regardless of the limitations of the |
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401 | operating system. |
| 368 | |
402 | |
| 369 | Please note, however, that "aio_sendfile" can read more bytes from |
403 | As native sendfile syscalls (as practically any non-POSIX interface |
| 370 | $in_fh than are written, and there is no way to find out how many |
404 | hacked together in a hurry to improve benchmark numbers) tend to be |
| 371 | bytes have been read from "aio_sendfile" alone, as "aio_sendfile" |
405 | rather buggy on many systems, this implementation tries to work |
| 372 | only provides the number of bytes written to $out_fh. Only if the |
406 | around some known bugs in Linux and FreeBSD kernels (probably |
| 373 | result value equals $length one can assume that $length bytes have |
407 | others, too), but that might fail, so you really really should check |
| 374 | been read. |
408 | the return value of "aio_sendfile" - fewre bytes than expected might |
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409 | have been transferred. |
| 375 | |
410 | |
| 376 | aio_readahead $fh,$offset,$length, $callback->($retval) |
411 | aio_readahead $fh,$offset,$length, $callback->($retval) |
| 377 | "aio_readahead" populates the page cache with data from a file so |
412 | "aio_readahead" populates the page cache with data from a file so |
| 378 | that subsequent reads from that file will not block on disk I/O. The |
413 | that subsequent reads from that file will not block on disk I/O. The |
| 379 | $offset argument specifies the starting point from which data is to |
414 | $offset argument specifies the starting point from which data is to |
| … | |
… | |
| 399 | |
434 | |
| 400 | Currently, the stats are always 64-bit-stats, i.e. instead of |
435 | Currently, the stats are always 64-bit-stats, i.e. instead of |
| 401 | returning an error when stat'ing a large file, the results will be |
436 | returning an error when stat'ing a large file, the results will be |
| 402 | silently truncated unless perl itself is compiled with large file |
437 | silently truncated unless perl itself is compiled with large file |
| 403 | support. |
438 | support. |
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439 | |
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440 | To help interpret the mode and dev/rdev stat values, IO::AIO offers |
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441 | the following constants and functions (if not implemented, the |
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442 | constants will be 0 and the functions will either "croak" or fall |
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443 | back on traditional behaviour). |
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444 | |
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445 | "S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG", |
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446 | "S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t", |
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447 | "IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor". |
| 404 | |
448 | |
| 405 | Example: Print the length of /etc/passwd: |
449 | Example: Print the length of /etc/passwd: |
| 406 | |
450 | |
| 407 | aio_stat "/etc/passwd", sub { |
451 | aio_stat "/etc/passwd", sub { |
| 408 | $_[0] and die "stat failed: $!"; |
452 | $_[0] and die "stat failed: $!"; |
| … | |
… | |
| 497 | |
541 | |
| 498 | The only (POSIX-) portable way of calling this function is: |
542 | The only (POSIX-) portable way of calling this function is: |
| 499 | |
543 | |
| 500 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
544 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
| 501 | |
545 | |
|
|
546 | See "aio_stat" for info about some potentially helpful extra |
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547 | constants and functions. |
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548 | |
| 502 | aio_link $srcpath, $dstpath, $callback->($status) |
549 | aio_link $srcpath, $dstpath, $callback->($status) |
| 503 | Asynchronously create a new link to the existing object at $srcpath |
550 | Asynchronously create a new link to the existing object at $srcpath |
| 504 | at the path $dstpath and call the callback with the result code. |
551 | at the path $dstpath and call the callback with the result code. |
| 505 | |
552 | |
| 506 | aio_symlink $srcpath, $dstpath, $callback->($status) |
553 | aio_symlink $srcpath, $dstpath, $callback->($status) |
| … | |
… | |
| 511 | aio_readlink $path, $callback->($link) |
558 | aio_readlink $path, $callback->($link) |
| 512 | Asynchronously read the symlink specified by $path and pass it to |
559 | Asynchronously read the symlink specified by $path and pass it to |
| 513 | the callback. If an error occurs, nothing or undef gets passed to |
560 | the callback. If an error occurs, nothing or undef gets passed to |
| 514 | the callback. |
561 | the callback. |
| 515 | |
562 | |
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563 | aio_realpath $path, $callback->($path) |
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564 | Asynchronously make the path absolute and resolve any symlinks in |
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565 | $path. The resulting path only consists of directories (Same as |
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566 | Cwd::realpath). |
|
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567 | |
|
|
568 | This request can be used to get the absolute path of the current |
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569 | working directory by passing it a path of . (a single dot). |
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570 | |
| 516 | aio_rename $srcpath, $dstpath, $callback->($status) |
571 | aio_rename $srcpath, $dstpath, $callback->($status) |
| 517 | Asynchronously rename the object at $srcpath to $dstpath, just as |
572 | Asynchronously rename the object at $srcpath to $dstpath, just as |
| 518 | rename(2) and call the callback with the result code. |
573 | rename(2) and call the callback with the result code. |
| 519 | |
574 | |
| 520 | aio_mkdir $pathname, $mode, $callback->($status) |
575 | aio_mkdir $pathname, $mode, $callback->($status) |
| … | |
… | |
| 542 | The flags are a combination of the following constants, ORed |
597 | The flags are a combination of the following constants, ORed |
| 543 | together (the flags will also be passed to the callback, possibly |
598 | together (the flags will also be passed to the callback, possibly |
| 544 | modified): |
599 | modified): |
| 545 | |
600 | |
| 546 | IO::AIO::READDIR_DENTS |
601 | IO::AIO::READDIR_DENTS |
| 547 | When this flag is off, then the callback gets an arrayref with |
602 | When this flag is off, then the callback gets an arrayref |
| 548 | of names only (as with "aio_readdir"), otherwise it gets an |
603 | consisting of names only (as with "aio_readdir"), otherwise it |
| 549 | arrayref with "[$name, $type, $inode]" arrayrefs, each |
604 | gets an arrayref with "[$name, $type, $inode]" arrayrefs, each |
| 550 | describing a single directory entry in more detail. |
605 | describing a single directory entry in more detail. |
| 551 | |
606 | |
| 552 | $name is the name of the entry. |
607 | $name is the name of the entry. |
| 553 | |
608 | |
| 554 | $type is one of the "IO::AIO::DT_xxx" constants: |
609 | $type is one of the "IO::AIO::DT_xxx" constants: |
| … | |
… | |
| 567 | unspecified content on systems that do not deliver the inode |
622 | unspecified content on systems that do not deliver the inode |
| 568 | information. |
623 | information. |
| 569 | |
624 | |
| 570 | IO::AIO::READDIR_DIRS_FIRST |
625 | IO::AIO::READDIR_DIRS_FIRST |
| 571 | When this flag is set, then the names will be returned in an |
626 | When this flag is set, then the names will be returned in an |
| 572 | order where likely directories come first. This is useful when |
627 | order where likely directories come first, in optimal stat |
| 573 | you need to quickly find directories, or you want to find all |
628 | order. This is useful when you need to quickly find directories, |
| 574 | directories while avoiding to stat() each entry. |
629 | or you want to find all directories while avoiding to stat() |
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|
630 | each entry. |
| 575 | |
631 | |
| 576 | If the system returns type information in readdir, then this is |
632 | If the system returns type information in readdir, then this is |
| 577 | used to find directories directly. Otherwise, likely directories |
633 | used to find directories directly. Otherwise, likely directories |
| 578 | are files beginning with ".", or otherwise files with no dots, |
634 | are names beginning with ".", or otherwise names with no dots, |
| 579 | of which files with short names are tried first. |
635 | of which names with short names are tried first. |
| 580 | |
636 | |
| 581 | IO::AIO::READDIR_STAT_ORDER |
637 | IO::AIO::READDIR_STAT_ORDER |
| 582 | When this flag is set, then the names will be returned in an |
638 | When this flag is set, then the names will be returned in an |
| 583 | order suitable for stat()'ing each one. That is, when you plan |
639 | order suitable for stat()'ing each one. That is, when you plan |
| 584 | to stat() all files in the given directory, then the returned |
640 | to stat() all files in the given directory, then the returned |
| … | |
… | |
| 751 | "aio_msync", above, except for flags, which must be either 0 (which |
807 | "aio_msync", above, except for flags, which must be either 0 (which |
| 752 | reads all pages and ensures they are instantiated) or |
808 | reads all pages and ensures they are instantiated) or |
| 753 | "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading |
809 | "IO::AIO::MT_MODIFY", which modifies the memory page s(by reading |
| 754 | and writing an octet from it, which dirties the page). |
810 | and writing an octet from it, which dirties the page). |
| 755 | |
811 | |
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812 | aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status) |
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|
813 | This is a rather advanced IO::AIO call, which works best on |
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814 | mmap(2)ed scalars. |
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815 | |
|
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816 | It reads in all the pages of the underlying storage into memory (if |
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817 | any) and locks them, so they are not getting swapped/paged out or |
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818 | removed. |
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819 | |
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820 | If $length is undefined, then the scalar will be locked till the |
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821 | end. |
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822 | |
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823 | On systems that do not implement "mlock", this function returns -1 |
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824 | and sets errno to "ENOSYS". |
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825 | |
|
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826 | Note that the corresponding "munlock" is synchronous and is |
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827 | documented under "MISCELLANEOUS FUNCTIONS". |
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828 | |
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829 | Example: open a file, mmap and mlock it - both will be undone when |
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830 | $data gets destroyed. |
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831 | |
|
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832 | open my $fh, "<", $path or die "$path: $!"; |
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833 | my $data; |
|
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834 | IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh; |
|
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835 | aio_mlock $data; # mlock in background |
|
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836 | |
|
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837 | aio_mlockall $flags, $callback->($status) |
|
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838 | Calls the "mlockall" function with the given $flags (a combination |
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839 | of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE"). |
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840 | |
|
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841 | On systems that do not implement "mlockall", this function returns |
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842 | -1 and sets errno to "ENOSYS". |
|
|
843 | |
|
|
844 | Note that the corresponding "munlockall" is synchronous and is |
|
|
845 | documented under "MISCELLANEOUS FUNCTIONS". |
|
|
846 | |
|
|
847 | Example: asynchronously lock all current and future pages into |
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848 | memory. |
|
|
849 | |
|
|
850 | aio_mlockall IO::AIO::MCL_FUTURE; |
|
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851 | |
| 756 | aio_group $callback->(...) |
852 | aio_group $callback->(...) |
| 757 | This is a very special aio request: Instead of doing something, it |
853 | This is a very special aio request: Instead of doing something, it |
| 758 | is a container for other aio requests, which is useful if you want |
854 | is a container for other aio requests, which is useful if you want |
| 759 | to bundle many requests into a single, composite, request with a |
855 | to bundle many requests into a single, composite, request with a |
| 760 | definite callback and the ability to cancel the whole request with |
856 | definite callback and the ability to cancel the whole request with |
| … | |
… | |
| 955 | |
1051 | |
| 956 | See "poll_cb" for an example. |
1052 | See "poll_cb" for an example. |
| 957 | |
1053 | |
| 958 | IO::AIO::poll_cb |
1054 | IO::AIO::poll_cb |
| 959 | Process some outstanding events on the result pipe. You have to call |
1055 | Process some outstanding events on the result pipe. You have to call |
| 960 | this regularly. Returns 0 if all events could be processed, or -1 if |
1056 | this regularly. Returns 0 if all events could be processed (or there |
| 961 | it returned earlier for whatever reason. Returns immediately when no |
1057 | were no events to process), or -1 if it returned earlier for |
| 962 | events are outstanding. The amount of events processed depends on |
1058 | whatever reason. Returns immediately when no events are outstanding. |
| 963 | the settings of "IO::AIO::max_poll_req" and |
1059 | The amount of events processed depends on the settings of |
| 964 | "IO::AIO::max_poll_time". |
1060 | "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". |
| 965 | |
1061 | |
| 966 | If not all requests were processed for whatever reason, the |
1062 | If not all requests were processed for whatever reason, the |
| 967 | filehandle will still be ready when "poll_cb" returns, so normally |
1063 | filehandle will still be ready when "poll_cb" returns, so normally |
| 968 | you don't have to do anything special to have it called later. |
1064 | you don't have to do anything special to have it called later. |
|
|
1065 | |
|
|
1066 | Apart from calling "IO::AIO::poll_cb" when the event filehandle |
|
|
1067 | becomes ready, it can be beneficial to call this function from loops |
|
|
1068 | which submit a lot of requests, to make sure the results get |
|
|
1069 | processed when they become available and not just when the loop is |
|
|
1070 | finished and the event loop takes over again. This function returns |
|
|
1071 | very fast when there are no outstanding requests. |
| 969 | |
1072 | |
| 970 | Example: Install an Event watcher that automatically calls |
1073 | Example: Install an Event watcher that automatically calls |
| 971 | IO::AIO::poll_cb with high priority (more examples can be found in |
1074 | IO::AIO::poll_cb with high priority (more examples can be found in |
| 972 | the SYNOPSIS section, at the top of this document): |
1075 | the SYNOPSIS section, at the top of this document): |
| 973 | |
1076 | |
| … | |
… | |
| 1067 | |
1170 | |
| 1068 | Under normal circumstances you don't need to call this function. |
1171 | Under normal circumstances you don't need to call this function. |
| 1069 | |
1172 | |
| 1070 | IO::AIO::max_idle $nthreads |
1173 | IO::AIO::max_idle $nthreads |
| 1071 | Limit the number of threads (default: 4) that are allowed to idle |
1174 | Limit the number of threads (default: 4) that are allowed to idle |
| 1072 | (i.e., threads that did not get a request to process within 10 |
1175 | (i.e., threads that did not get a request to process within the idle |
| 1073 | seconds). That means if a thread becomes idle while $nthreads other |
1176 | timeout (default: 10 seconds). That means if a thread becomes idle |
| 1074 | threads are also idle, it will free its resources and exit. |
1177 | while $nthreads other threads are also idle, it will free its |
|
|
1178 | resources and exit. |
| 1075 | |
1179 | |
| 1076 | This is useful when you allow a large number of threads (e.g. 100 or |
1180 | This is useful when you allow a large number of threads (e.g. 100 or |
| 1077 | 1000) to allow for extremely high load situations, but want to free |
1181 | 1000) to allow for extremely high load situations, but want to free |
| 1078 | resources under normal circumstances (1000 threads can easily |
1182 | resources under normal circumstances (1000 threads can easily |
| 1079 | consume 30MB of RAM). |
1183 | consume 30MB of RAM). |
| 1080 | |
1184 | |
| 1081 | The default is probably ok in most situations, especially if thread |
1185 | The default is probably ok in most situations, especially if thread |
| 1082 | creation is fast. If thread creation is very slow on your system you |
1186 | creation is fast. If thread creation is very slow on your system you |
| 1083 | might want to use larger values. |
1187 | might want to use larger values. |
| 1084 | |
1188 | |
|
|
1189 | IO::AIO::idle_timeout $seconds |
|
|
1190 | Sets the minimum idle timeout (default 10) after which worker |
|
|
1191 | threads are allowed to exit. SEe "IO::AIO::max_idle". |
|
|
1192 | |
| 1085 | IO::AIO::max_outstanding $maxreqs |
1193 | IO::AIO::max_outstanding $maxreqs |
|
|
1194 | Sets the maximum number of outstanding requests to $nreqs. If you do |
|
|
1195 | queue up more than this number of requests, the next call to |
|
|
1196 | "IO::AIO::poll_cb" (and other functions calling "poll_cb", such as |
|
|
1197 | "IO::AIO::flush" or "IO::AIO::poll") will block until the limit is |
|
|
1198 | no longer exceeded. |
|
|
1199 | |
|
|
1200 | In other words, this setting does not enforce a queue limit, but can |
|
|
1201 | be used to make poll functions block if the limit is exceeded. |
|
|
1202 | |
| 1086 | This is a very bad function to use in interactive programs because |
1203 | This is a very bad function to use in interactive programs because |
| 1087 | it blocks, and a bad way to reduce concurrency because it is |
1204 | it blocks, and a bad way to reduce concurrency because it is |
| 1088 | inexact: Better use an "aio_group" together with a feed callback. |
1205 | inexact: Better use an "aio_group" together with a feed callback. |
| 1089 | |
1206 | |
| 1090 | Sets the maximum number of outstanding requests to $nreqs. If you do |
1207 | It's main use is in scripts without an event loop - when you want to |
| 1091 | queue up more than this number of requests, the next call to the |
1208 | stat a lot of files, you can write somehting like this: |
| 1092 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
|
|
| 1093 | function will block until the limit is no longer exceeded. |
|
|
| 1094 | |
1209 | |
| 1095 | The default value is very large, so there is no practical limit on |
1210 | IO::AIO::max_outstanding 32; |
|
|
1211 | |
|
|
1212 | for my $path (...) { |
|
|
1213 | aio_stat $path , ...; |
|
|
1214 | IO::AIO::poll_cb; |
|
|
1215 | } |
|
|
1216 | |
|
|
1217 | IO::AIO::flush; |
|
|
1218 | |
|
|
1219 | The call to "poll_cb" inside the loop will normally return |
|
|
1220 | instantly, but as soon as more thna 32 reqeusts are in-flight, it |
|
|
1221 | will block until some requests have been handled. This keeps the |
|
|
1222 | loop from pushing a large number of "aio_stat" requests onto the |
|
|
1223 | queue. |
|
|
1224 | |
|
|
1225 | The default value for "max_outstanding" is very large, so there is |
| 1096 | the number of outstanding requests. |
1226 | no practical limit on the number of outstanding requests. |
| 1097 | |
|
|
| 1098 | You can still queue as many requests as you want. Therefore, |
|
|
| 1099 | "max_outstanding" is mainly useful in simple scripts (with low |
|
|
| 1100 | values) or as a stop gap to shield against fatal memory overflow |
|
|
| 1101 | (with large values). |
|
|
| 1102 | |
1227 | |
| 1103 | STATISTICAL INFORMATION |
1228 | STATISTICAL INFORMATION |
| 1104 | IO::AIO::nreqs |
1229 | IO::AIO::nreqs |
| 1105 | Returns the number of requests currently in the ready, execute or |
1230 | Returns the number of requests currently in the ready, execute or |
| 1106 | pending states (i.e. for which their callback has not been invoked |
1231 | pending states (i.e. for which their callback has not been invoked |
| … | |
… | |
| 1130 | set to non-blocking operations). |
1255 | set to non-blocking operations). |
| 1131 | |
1256 | |
| 1132 | Returns the number of bytes copied, or -1 on error. |
1257 | Returns the number of bytes copied, or -1 on error. |
| 1133 | |
1258 | |
| 1134 | IO::AIO::fadvise $fh, $offset, $len, $advice |
1259 | IO::AIO::fadvise $fh, $offset, $len, $advice |
| 1135 | Simply calls the "posix_fadvise" function (see it's manpage for |
1260 | Simply calls the "posix_fadvise" function (see its manpage for |
| 1136 | details). The following advice constants are avaiable: |
1261 | details). The following advice constants are avaiable: |
| 1137 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
1262 | "IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL", |
| 1138 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
1263 | "IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE", |
| 1139 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
1264 | "IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED". |
| 1140 | |
1265 | |
| 1141 | On systems that do not implement "posix_fadvise", this function |
1266 | On systems that do not implement "posix_fadvise", this function |
| 1142 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
1267 | returns ENOSYS, otherwise the return value of "posix_fadvise". |
|
|
1268 | |
|
|
1269 | IO::AIO::madvise $scalar, $offset, $len, $advice |
|
|
1270 | Simply calls the "posix_madvise" function (see its manpage for |
|
|
1271 | details). The following advice constants are avaiable: |
|
|
1272 | "IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL", |
|
|
1273 | "IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED", |
|
|
1274 | "IO::AIO::MADV_DONTNEED". |
|
|
1275 | |
|
|
1276 | On systems that do not implement "posix_madvise", this function |
|
|
1277 | returns ENOSYS, otherwise the return value of "posix_madvise". |
|
|
1278 | |
|
|
1279 | IO::AIO::mprotect $scalar, $offset, $len, $protect |
|
|
1280 | Simply calls the "mprotect" function on the preferably AIO::mmap'ed |
|
|
1281 | $scalar (see its manpage for details). The following protect |
|
|
1282 | constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ", |
|
|
1283 | "IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC". |
|
|
1284 | |
|
|
1285 | On systems that do not implement "mprotect", this function returns |
|
|
1286 | ENOSYS, otherwise the return value of "mprotect". |
| 1143 | |
1287 | |
| 1144 | IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
1288 | IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset] |
| 1145 | Memory-maps a file (or anonymous memory range) and attaches it to |
1289 | Memory-maps a file (or anonymous memory range) and attaches it to |
| 1146 | the given $scalar, which will act like a string scalar. |
1290 | the given $scalar, which will act like a string scalar. |
| 1147 | |
1291 | |
| … | |
… | |
| 1192 | my $fast_md5 = md5 $data; |
1336 | my $fast_md5 = md5 $data; |
| 1193 | |
1337 | |
| 1194 | IO::AIO::munmap $scalar |
1338 | IO::AIO::munmap $scalar |
| 1195 | Removes a previous mmap and undefines the $scalar. |
1339 | Removes a previous mmap and undefines the $scalar. |
| 1196 | |
1340 | |
| 1197 | IO::AIO::mlockall $flags |
1341 | IO::AIO::munlock $scalar, $offset = 0, $length = undef |
| 1198 | Calls the "mlockall" function with the given $flags (a combination |
1342 | Calls the "munlock" function, undoing the effects of a previous |
| 1199 | of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL__FUTURE"). |
1343 | "aio_mlock" call (see its description for details). |
| 1200 | |
|
|
| 1201 | On systems that do not implement "mlockall", this function returns |
|
|
| 1202 | ENOSYS, otherwise the return value of "mlockall". |
|
|
| 1203 | |
1344 | |
| 1204 | IO::AIO::munlockall |
1345 | IO::AIO::munlockall |
| 1205 | Calls the "munlockall" function. |
1346 | Calls the "munlockall" function. |
| 1206 | |
1347 | |
| 1207 | On systems that do not implement "munlockall", this function returns |
1348 | On systems that do not implement "munlockall", this function returns |
| … | |
… | |
| 1236 | # Danga::Socket integration |
1377 | # Danga::Socket integration |
| 1237 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
1378 | Danga::Socket->AddOtherFds (IO::AIO::poll_fileno => |
| 1238 | \&IO::AIO::poll_cb); |
1379 | \&IO::AIO::poll_cb); |
| 1239 | |
1380 | |
| 1240 | FORK BEHAVIOUR |
1381 | FORK BEHAVIOUR |
| 1241 | This module should do "the right thing" when the process using it forks: |
1382 | Usage of pthreads in a program changes the semantics of fork |
|
|
1383 | considerably. Specifically, only async-safe functions can be called |
|
|
1384 | after fork. Perl doesn't know about this, so in general, you cannot call |
|
|
1385 | fork with defined behaviour in perl if pthreads are involved. IO::AIO |
|
|
1386 | uses pthreads, so this applies, but many other extensions and (for |
|
|
1387 | inexplicable reasons) perl itself often is linked against pthreads, so |
|
|
1388 | this limitation applies to quite a lot of perls. |
| 1242 | |
1389 | |
| 1243 | Before the fork, IO::AIO enters a quiescent state where no requests can |
1390 | This module no longer tries to fight your OS, or POSIX. That means |
| 1244 | be added in other threads and no results will be processed. After the |
1391 | IO::AIO only works in the process that loaded it. Forking is fully |
| 1245 | fork the parent simply leaves the quiescent state and continues |
1392 | supported, but using IO::AIO in the child is not. |
| 1246 | request/result processing, while the child frees the request/result |
|
|
| 1247 | queue (so that the requests started before the fork will only be handled |
|
|
| 1248 | in the parent). Threads will be started on demand until the limit set in |
|
|
| 1249 | the parent process has been reached again. |
|
|
| 1250 | |
1393 | |
| 1251 | In short: the parent will, after a short pause, continue as if fork had |
1394 | You might get around by not *using* IO::AIO before (or after) forking. |
| 1252 | not been called, while the child will act as if IO::AIO has not been |
1395 | You could also try to call the IO::AIO::reinit function in the child: |
| 1253 | used yet. |
1396 | |
|
|
1397 | IO::AIO::reinit |
|
|
1398 | Abondons all current requests and I/O threads and simply |
|
|
1399 | reinitialises all data structures. This is not an operation |
|
|
1400 | suppported by any standards, but happens to work on GNU/Linux and |
|
|
1401 | some newer BSD systems. |
|
|
1402 | |
|
|
1403 | The only reasonable use for this function is to call it after |
|
|
1404 | forking, if "IO::AIO" was used in the parent. Calling it while |
|
|
1405 | IO::AIO is active in the process will result in undefined behaviour. |
|
|
1406 | Calling it at any time will also result in any undefined (by POSIX) |
|
|
1407 | behaviour. |
| 1254 | |
1408 | |
| 1255 | MEMORY USAGE |
1409 | MEMORY USAGE |
| 1256 | Per-request usage: |
1410 | Per-request usage: |
| 1257 | |
1411 | |
| 1258 | Each aio request uses - depending on your architecture - around 100-200 |
1412 | Each aio request uses - depending on your architecture - around 100-200 |
