… | |
… | |
58 | but can also be used to easily do operations in parallel that are |
58 | but can also be used to easily do operations in parallel that are |
59 | normally done sequentially, e.g. stat'ing many files, which is much |
59 | normally done sequentially, e.g. stat'ing many files, which is much |
60 | faster on a RAID volume or over NFS when you do a number of stat |
60 | faster on a RAID volume or over NFS when you do a number of stat |
61 | operations concurrently. |
61 | operations concurrently. |
62 | |
62 | |
63 | While this works on all types of file descriptors (for example sockets), |
63 | While most of this works on all types of file descriptors (for example |
64 | using these functions on file descriptors that support nonblocking |
64 | sockets), using these functions on file descriptors that support |
65 | operation (again, sockets, pipes etc.) is very inefficient. Use an event |
65 | nonblocking operation (again, sockets, pipes etc.) is very inefficient |
|
|
66 | or might not work (aio_read fails on sockets/pipes/fifos). Use an event |
66 | loop for that (such as the Event module): IO::AIO will naturally fit |
67 | loop for that (such as the Event module): IO::AIO will naturally fit |
67 | into such an event loop itself. |
68 | into such an event loop itself. |
68 | |
69 | |
69 | In this version, a number of threads are started that execute your |
70 | In this version, a number of threads are started that execute your |
70 | requests and signal their completion. You don't need thread support in |
71 | requests and signal their completion. You don't need thread support in |
… | |
… | |
167 | the actual aio request is severed and calling its methods will |
168 | the actual aio request is severed and calling its methods will |
168 | either do nothing or result in a runtime error). |
169 | either do nothing or result in a runtime error). |
169 | |
170 | |
170 | FUNCTIONS |
171 | FUNCTIONS |
171 | AIO REQUEST FUNCTIONS |
172 | AIO REQUEST FUNCTIONS |
172 | All the "aio_*" calls are more or less thin wrappers around the |
173 | All the "aio_*" calls are more or less thin wrappers around the syscall |
173 | syscall with the same name (sans "aio_"). The arguments are similar |
174 | with the same name (sans "aio_"). The arguments are similar or |
174 | or identical, and they all accept an additional (and optional) |
175 | identical, and they all accept an additional (and optional) $callback |
175 | $callback argument which must be a code reference. This code |
176 | argument which must be a code reference. This code reference will get |
176 | reference will get called with the syscall return code (e.g. most |
177 | called with the syscall return code (e.g. most syscalls return -1 on |
177 | syscalls return -1 on error, unlike perl, which usually delivers |
178 | error, unlike perl, which usually delivers "false") as it's sole |
178 | "false") as it's sole argument when the given syscall has been |
179 | argument when the given syscall has been executed asynchronously. |
179 | executed asynchronously. |
|
|
180 | |
180 | |
181 | All functions expecting a filehandle keep a copy of the filehandle |
181 | All functions expecting a filehandle keep a copy of the filehandle |
182 | internally until the request has finished. |
182 | internally until the request has finished. |
183 | |
183 | |
184 | All functions return request objects of type IO::AIO::REQ that allow |
184 | All functions return request objects of type IO::AIO::REQ that allow |
185 | further manipulation of those requests while they are in-flight. |
185 | further manipulation of those requests while they are in-flight. |
186 | |
186 | |
187 | The pathnames you pass to these routines *must* be absolute and |
187 | The pathnames you pass to these routines *must* be absolute and encoded |
188 | encoded as octets. The reason for the former is that at the time the |
188 | as octets. The reason for the former is that at the time the request is |
189 | request is being executed, the current working directory could have |
189 | being executed, the current working directory could have changed. |
190 | changed. Alternatively, you can make sure that you never change the |
190 | Alternatively, you can make sure that you never change the current |
191 | current working directory anywhere in the program and then use |
191 | working directory anywhere in the program and then use relative paths. |
192 | relative paths. |
|
|
193 | |
192 | |
194 | To encode pathnames as octets, either make sure you either: a) |
193 | To encode pathnames as octets, either make sure you either: a) always |
195 | always pass in filenames you got from outside (command line, readdir |
194 | pass in filenames you got from outside (command line, readdir etc.) |
196 | etc.) without tinkering, b) are ASCII or ISO 8859-1, c) use the |
195 | without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module |
197 | Encode module and encode your pathnames to the locale (or other) |
196 | and encode your pathnames to the locale (or other) encoding in effect in |
198 | encoding in effect in the user environment, d) use |
197 | the user environment, d) use Glib::filename_from_unicode on unicode |
199 | Glib::filename_from_unicode on unicode filenames or e) use something |
198 | filenames or e) use something else to ensure your scalar has the correct |
200 | else to ensure your scalar has the correct contents. |
199 | contents. |
201 | |
200 | |
202 | This works, btw. independent of the internal UTF-8 bit, which |
201 | This works, btw. independent of the internal UTF-8 bit, which IO::AIO |
203 | IO::AIO handles correctly wether it is set or not. |
202 | handles correctly wether it is set or not. |
204 | |
203 | |
205 | $prev_pri = aioreq_pri [$pri] |
204 | $prev_pri = aioreq_pri [$pri] |
206 | Returns the priority value that would be used for the next |
205 | Returns the priority value that would be used for the next request |
207 | request and, if $pri is given, sets the priority for the next |
206 | and, if $pri is given, sets the priority for the next aio request. |
208 | aio request. |
|
|
209 | |
207 | |
210 | The default priority is 0, the minimum and maximum priorities |
208 | The default priority is 0, the minimum and maximum priorities are -4 |
211 | are -4 and 4, respectively. Requests with higher priority will |
209 | and 4, respectively. Requests with higher priority will be serviced |
212 | be serviced first. |
210 | first. |
213 | |
211 | |
214 | The priority will be reset to 0 after each call to one of the |
212 | The priority will be reset to 0 after each call to one of the |
215 | "aio_*" functions. |
213 | "aio_*" functions. |
216 | |
214 | |
217 | Example: open a file with low priority, then read something from |
215 | Example: open a file with low priority, then read something from it |
218 | it with higher priority so the read request is serviced before |
216 | with higher priority so the read request is serviced before other |
219 | other low priority open requests (potentially spamming the |
217 | low priority open requests (potentially spamming the cache): |
220 | cache): |
|
|
221 | |
218 | |
|
|
219 | aioreq_pri -3; |
|
|
220 | aio_open ..., sub { |
|
|
221 | return unless $_[0]; |
|
|
222 | |
222 | aioreq_pri -3; |
223 | aioreq_pri -2; |
223 | aio_open ..., sub { |
|
|
224 | return unless $_[0]; |
|
|
225 | |
|
|
226 | aioreq_pri -2; |
|
|
227 | aio_read $_[0], ..., sub { |
224 | aio_read $_[0], ..., sub { |
228 | ... |
|
|
229 | }; |
|
|
230 | }; |
|
|
231 | |
|
|
232 | aioreq_nice $pri_adjust |
|
|
233 | Similar to "aioreq_pri", but subtracts the given value from the |
|
|
234 | current priority, so the effect is cumulative. |
|
|
235 | |
|
|
236 | aio_open $pathname, $flags, $mode, $callback->($fh) |
|
|
237 | Asynchronously open or create a file and call the callback with |
|
|
238 | a newly created filehandle for the file. |
|
|
239 | |
|
|
240 | The pathname passed to "aio_open" must be absolute. See API |
|
|
241 | NOTES, above, for an explanation. |
|
|
242 | |
|
|
243 | The $flags argument is a bitmask. See the "Fcntl" module for a |
|
|
244 | list. They are the same as used by "sysopen". |
|
|
245 | |
|
|
246 | Likewise, $mode specifies the mode of the newly created file, if |
|
|
247 | it didn't exist and "O_CREAT" has been given, just like perl's |
|
|
248 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
|
|
249 | create new files, and 0666 or 0777 if you do). |
|
|
250 | |
|
|
251 | Example: |
|
|
252 | |
|
|
253 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
|
|
254 | if ($_[0]) { |
|
|
255 | print "open successful, fh is $_[0]\n"; |
|
|
256 | ... |
|
|
257 | } else { |
|
|
258 | die "open failed: $!\n"; |
|
|
259 | } |
|
|
260 | }; |
|
|
261 | |
|
|
262 | aio_close $fh, $callback->($status) |
|
|
263 | Asynchronously close a file and call the callback with the |
|
|
264 | result code. *WARNING:* although accepted, you should not pass |
|
|
265 | in a perl filehandle here, as perl will likely close the file |
|
|
266 | descriptor another time when the filehandle is destroyed. |
|
|
267 | Normally, you can safely call perls "close" or just let |
|
|
268 | filehandles go out of scope. |
|
|
269 | |
|
|
270 | This is supposed to be a bug in the API, so that might change. |
|
|
271 | It's therefore best to avoid this function. |
|
|
272 | |
|
|
273 | aio_read $fh,$offset,$length, $data,$dataoffset, |
|
|
274 | $callback->($retval) |
|
|
275 | aio_write $fh,$offset,$length, $data,$dataoffset, |
|
|
276 | $callback->($retval) |
|
|
277 | Reads or writes "length" bytes from the specified "fh" and |
|
|
278 | "offset" into the scalar given by "data" and offset "dataoffset" |
|
|
279 | and calls the callback without the actual number of bytes read |
|
|
280 | (or -1 on error, just like the syscall). |
|
|
281 | |
|
|
282 | The $data scalar *MUST NOT* be modified in any way while the |
|
|
283 | request is outstanding. Modifying it can result in segfaults or |
|
|
284 | WW3 (if the necessary/optional hardware is installed). |
|
|
285 | |
|
|
286 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting |
|
|
287 | at offset 0 within the scalar: |
|
|
288 | |
|
|
289 | aio_read $fh, 7, 15, $buffer, 0, sub { |
|
|
290 | $_[0] > 0 or die "read error: $!"; |
|
|
291 | print "read $_[0] bytes: <$buffer>\n"; |
|
|
292 | }; |
|
|
293 | |
|
|
294 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, |
|
|
295 | $callback->($retval) |
|
|
296 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
|
|
297 | reading at byte offset $in_offset, and starts writing at the |
|
|
298 | current file offset of $out_fh. Because of that, it is not safe |
|
|
299 | to issue more than one "aio_sendfile" per $out_fh, as they will |
|
|
300 | interfere with each other. |
|
|
301 | |
|
|
302 | This call tries to make use of a native "sendfile" syscall to |
|
|
303 | provide zero-copy operation. For this to work, $out_fh should |
|
|
304 | refer to a socket, and $in_fh should refer to mmap'able file. |
|
|
305 | |
|
|
306 | If the native sendfile call fails or is not implemented, it will |
|
|
307 | be emulated, so you can call "aio_sendfile" on any type of |
|
|
308 | filehandle regardless of the limitations of the operating |
|
|
309 | system. |
|
|
310 | |
|
|
311 | Please note, however, that "aio_sendfile" can read more bytes |
|
|
312 | from $in_fh than are written, and there is no way to find out |
|
|
313 | how many bytes have been read from "aio_sendfile" alone, as |
|
|
314 | "aio_sendfile" only provides the number of bytes written to |
|
|
315 | $out_fh. Only if the result value equals $length one can assume |
|
|
316 | that $length bytes have been read. |
|
|
317 | |
|
|
318 | aio_readahead $fh,$offset,$length, $callback->($retval) |
|
|
319 | "aio_readahead" populates the page cache with data from a file |
|
|
320 | so that subsequent reads from that file will not block on disk |
|
|
321 | I/O. The $offset argument specifies the starting point from |
|
|
322 | which data is to be read and $length specifies the number of |
|
|
323 | bytes to be read. I/O is performed in whole pages, so that |
|
|
324 | offset is effectively rounded down to a page boundary and bytes |
|
|
325 | are read up to the next page boundary greater than or equal to |
|
|
326 | (off-set+length). "aio_readahead" does not read beyond the end |
|
|
327 | of the file. The current file offset of the file is left |
|
|
328 | unchanged. |
|
|
329 | |
|
|
330 | If that syscall doesn't exist (likely if your OS isn't Linux) it |
|
|
331 | will be emulated by simply reading the data, which would have a |
|
|
332 | similar effect. |
|
|
333 | |
|
|
334 | aio_stat $fh_or_path, $callback->($status) |
|
|
335 | aio_lstat $fh, $callback->($status) |
|
|
336 | Works like perl's "stat" or "lstat" in void context. The |
|
|
337 | callback will be called after the stat and the results will be |
|
|
338 | available using "stat _" or "-s _" etc... |
|
|
339 | |
|
|
340 | The pathname passed to "aio_stat" must be absolute. See API |
|
|
341 | NOTES, above, for an explanation. |
|
|
342 | |
|
|
343 | Currently, the stats are always 64-bit-stats, i.e. instead of |
|
|
344 | returning an error when stat'ing a large file, the results will |
|
|
345 | be silently truncated unless perl itself is compiled with large |
|
|
346 | file support. |
|
|
347 | |
|
|
348 | Example: Print the length of /etc/passwd: |
|
|
349 | |
|
|
350 | aio_stat "/etc/passwd", sub { |
|
|
351 | $_[0] and die "stat failed: $!"; |
|
|
352 | print "size is ", -s _, "\n"; |
|
|
353 | }; |
|
|
354 | |
|
|
355 | aio_unlink $pathname, $callback->($status) |
|
|
356 | Asynchronously unlink (delete) a file and call the callback with |
|
|
357 | the result code. |
|
|
358 | |
|
|
359 | aio_mknod $path, $mode, $dev, $callback->($status) |
|
|
360 | [EXPERIMENTAL] |
|
|
361 | |
|
|
362 | Asynchronously create a device node (or fifo). See mknod(2). |
|
|
363 | |
|
|
364 | The only (POSIX-) portable way of calling this function is: |
|
|
365 | |
|
|
366 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
|
|
367 | |
|
|
368 | aio_link $srcpath, $dstpath, $callback->($status) |
|
|
369 | Asynchronously create a new link to the existing object at |
|
|
370 | $srcpath at the path $dstpath and call the callback with the |
|
|
371 | result code. |
|
|
372 | |
|
|
373 | aio_symlink $srcpath, $dstpath, $callback->($status) |
|
|
374 | Asynchronously create a new symbolic link to the existing object |
|
|
375 | at $srcpath at the path $dstpath and call the callback with the |
|
|
376 | result code. |
|
|
377 | |
|
|
378 | aio_rename $srcpath, $dstpath, $callback->($status) |
|
|
379 | Asynchronously rename the object at $srcpath to $dstpath, just |
|
|
380 | as rename(2) and call the callback with the result code. |
|
|
381 | |
|
|
382 | aio_rmdir $pathname, $callback->($status) |
|
|
383 | Asynchronously rmdir (delete) a directory and call the callback |
|
|
384 | with the result code. |
|
|
385 | |
|
|
386 | aio_readdir $pathname, $callback->($entries) |
|
|
387 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
|
|
388 | entire directory (i.e. opendir + readdir + closedir). The |
|
|
389 | entries will not be sorted, and will NOT include the "." and |
|
|
390 | ".." entries. |
|
|
391 | |
|
|
392 | The callback a single argument which is either "undef" or an |
|
|
393 | array-ref with the filenames. |
|
|
394 | |
|
|
395 | aio_copy $srcpath, $dstpath, $callback->($status) |
|
|
396 | Try to copy the *file* (directories not supported as either |
|
|
397 | source or destination) from $srcpath to $dstpath and call the |
|
|
398 | callback with the 0 (error) or -1 ok. |
|
|
399 | |
|
|
400 | This is a composite request that it creates the destination file |
|
|
401 | with mode 0200 and copies the contents of the source file into |
|
|
402 | it using "aio_sendfile", followed by restoring atime, mtime, |
|
|
403 | access mode and uid/gid, in that order. |
|
|
404 | |
|
|
405 | If an error occurs, the partial destination file will be |
|
|
406 | unlinked, if possible, except when setting atime, mtime, access |
|
|
407 | mode and uid/gid, where errors are being ignored. |
|
|
408 | |
|
|
409 | aio_move $srcpath, $dstpath, $callback->($status) |
|
|
410 | Try to move the *file* (directories not supported as either |
|
|
411 | source or destination) from $srcpath to $dstpath and call the |
|
|
412 | callback with the 0 (error) or -1 ok. |
|
|
413 | |
|
|
414 | This is a composite request that tries to rename(2) the file |
|
|
415 | first. If rename files with "EXDEV", it copies the file with |
|
|
416 | "aio_copy" and, if that is successful, unlinking the $srcpath. |
|
|
417 | |
|
|
418 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
|
|
419 | Scans a directory (similar to "aio_readdir") but additionally |
|
|
420 | tries to efficiently separate the entries of directory $path |
|
|
421 | into two sets of names, directories you can recurse into |
|
|
422 | (directories), and ones you cannot recurse into (everything |
|
|
423 | else, including symlinks to directories). |
|
|
424 | |
|
|
425 | "aio_scandir" is a composite request that creates of many sub |
|
|
426 | requests_ $maxreq specifies the maximum number of outstanding |
|
|
427 | aio requests that this function generates. If it is "<= 0", then |
|
|
428 | a suitable default will be chosen (currently 4). |
|
|
429 | |
|
|
430 | On error, the callback is called without arguments, otherwise it |
|
|
431 | receives two array-refs with path-relative entry names. |
|
|
432 | |
|
|
433 | Example: |
|
|
434 | |
|
|
435 | aio_scandir $dir, 0, sub { |
|
|
436 | my ($dirs, $nondirs) = @_; |
|
|
437 | print "real directories: @$dirs\n"; |
|
|
438 | print "everything else: @$nondirs\n"; |
|
|
439 | }; |
|
|
440 | |
|
|
441 | Implementation notes. |
|
|
442 | |
|
|
443 | The "aio_readdir" cannot be avoided, but "stat()"'ing every |
|
|
444 | entry can. |
|
|
445 | |
|
|
446 | After reading the directory, the modification time, size etc. of |
|
|
447 | the directory before and after the readdir is checked, and if |
|
|
448 | they match (and isn't the current time), the link count will be |
|
|
449 | used to decide how many entries are directories (if >= 2). |
|
|
450 | Otherwise, no knowledge of the number of subdirectories will be |
|
|
451 | assumed. |
|
|
452 | |
|
|
453 | Then entries will be sorted into likely directories (everything |
|
|
454 | without a non-initial dot currently) and likely non-directories |
|
|
455 | (everything else). Then every entry plus an appended "/." will |
|
|
456 | be "stat"'ed, likely directories first. If that succeeds, it |
|
|
457 | assumes that the entry is a directory or a symlink to directory |
|
|
458 | (which will be checked seperately). This is often faster than |
|
|
459 | stat'ing the entry itself because filesystems might detect the |
|
|
460 | type of the entry without reading the inode data (e.g. ext2fs |
|
|
461 | filetype feature). |
|
|
462 | |
|
|
463 | If the known number of directories (link count - 2) has been |
|
|
464 | reached, the rest of the entries is assumed to be |
|
|
465 | non-directories. |
|
|
466 | |
|
|
467 | This only works with certainty on POSIX (= UNIX) filesystems, |
|
|
468 | which fortunately are the vast majority of filesystems around. |
|
|
469 | |
|
|
470 | It will also likely work on non-POSIX filesystems with reduced |
|
|
471 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
472 | disables the directory counting heuristic. |
|
|
473 | |
|
|
474 | aio_fsync $fh, $callback->($status) |
|
|
475 | Asynchronously call fsync on the given filehandle and call the |
|
|
476 | callback with the fsync result code. |
|
|
477 | |
|
|
478 | aio_fdatasync $fh, $callback->($status) |
|
|
479 | Asynchronously call fdatasync on the given filehandle and call |
|
|
480 | the callback with the fdatasync result code. |
|
|
481 | |
|
|
482 | If this call isn't available because your OS lacks it or it |
|
|
483 | couldn't be detected, it will be emulated by calling "fsync" |
|
|
484 | instead. |
|
|
485 | |
|
|
486 | aio_group $callback->(...) |
|
|
487 | This is a very special aio request: Instead of doing something, |
|
|
488 | it is a container for other aio requests, which is useful if you |
|
|
489 | want to bundle many requests into a single, composite, request |
|
|
490 | with a definite callback and the ability to cancel the whole |
|
|
491 | request with its subrequests. |
|
|
492 | |
|
|
493 | Returns an object of class IO::AIO::GRP. See its documentation |
|
|
494 | below for more info. |
|
|
495 | |
|
|
496 | Example: |
|
|
497 | |
|
|
498 | my $grp = aio_group sub { |
|
|
499 | print "all stats done\n"; |
|
|
500 | }; |
|
|
501 | |
|
|
502 | add $grp |
|
|
503 | (aio_stat ...), |
|
|
504 | (aio_stat ...), |
|
|
505 | ...; |
225 | ... |
506 | |
|
|
507 | aio_nop $callback->() |
|
|
508 | This is a special request - it does nothing in itself and is |
|
|
509 | only used for side effects, such as when you want to add a dummy |
|
|
510 | request to a group so that finishing the requests in the group |
|
|
511 | depends on executing the given code. |
|
|
512 | |
|
|
513 | While this request does nothing, it still goes through the |
|
|
514 | execution phase and still requires a worker thread. Thus, the |
|
|
515 | callback will not be executed immediately but only after other |
|
|
516 | requests in the queue have entered their execution phase. This |
|
|
517 | can be used to measure request latency. |
|
|
518 | |
|
|
519 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
|
|
520 | Mainly used for debugging and benchmarking, this aio request |
|
|
521 | puts one of the request workers to sleep for the given time. |
|
|
522 | |
|
|
523 | While it is theoretically handy to have simple I/O scheduling |
|
|
524 | requests like sleep and file handle readable/writable, the |
|
|
525 | overhead this creates is immense (it blocks a thread for a long |
|
|
526 | time) so do not use this function except to put your application |
|
|
527 | under artificial I/O pressure. |
|
|
528 | |
|
|
529 | IO::AIO::REQ CLASS |
|
|
530 | All non-aggregate "aio_*" functions return an object of this class |
|
|
531 | when called in non-void context. |
|
|
532 | |
|
|
533 | cancel $req |
|
|
534 | Cancels the request, if possible. Has the effect of skipping |
|
|
535 | execution when entering the execute state and skipping calling |
|
|
536 | the callback when entering the the result state, but will leave |
|
|
537 | the request otherwise untouched. That means that requests that |
|
|
538 | currently execute will not be stopped and resources held by the |
|
|
539 | request will not be freed prematurely. |
|
|
540 | |
|
|
541 | cb $req $callback->(...) |
|
|
542 | Replace (or simply set) the callback registered to the request. |
|
|
543 | |
|
|
544 | IO::AIO::GRP CLASS |
|
|
545 | This class is a subclass of IO::AIO::REQ, so all its methods apply |
|
|
546 | to objects of this class, too. |
|
|
547 | |
|
|
548 | A IO::AIO::GRP object is a special request that can contain multiple |
|
|
549 | other aio requests. |
|
|
550 | |
|
|
551 | You create one by calling the "aio_group" constructing function with |
|
|
552 | a callback that will be called when all contained requests have |
|
|
553 | entered the "done" state: |
|
|
554 | |
|
|
555 | my $grp = aio_group sub { |
|
|
556 | print "all requests are done\n"; |
|
|
557 | }; |
|
|
558 | |
|
|
559 | You add requests by calling the "add" method with one or more |
|
|
560 | "IO::AIO::REQ" objects: |
|
|
561 | |
|
|
562 | $grp->add (aio_unlink "..."); |
|
|
563 | |
|
|
564 | add $grp aio_stat "...", sub { |
|
|
565 | $_[0] or return $grp->result ("error"); |
|
|
566 | |
|
|
567 | # add another request dynamically, if first succeeded |
|
|
568 | add $grp aio_open "...", sub { |
|
|
569 | $grp->result ("ok"); |
|
|
570 | }; |
226 | }; |
571 | }; |
227 | }; |
572 | |
228 | |
|
|
229 | aioreq_nice $pri_adjust |
|
|
230 | Similar to "aioreq_pri", but subtracts the given value from the |
|
|
231 | current priority, so the effect is cumulative. |
|
|
232 | |
|
|
233 | aio_open $pathname, $flags, $mode, $callback->($fh) |
|
|
234 | Asynchronously open or create a file and call the callback with a |
|
|
235 | newly created filehandle for the file. |
|
|
236 | |
|
|
237 | The pathname passed to "aio_open" must be absolute. See API NOTES, |
|
|
238 | above, for an explanation. |
|
|
239 | |
|
|
240 | The $flags argument is a bitmask. See the "Fcntl" module for a list. |
|
|
241 | They are the same as used by "sysopen". |
|
|
242 | |
|
|
243 | Likewise, $mode specifies the mode of the newly created file, if it |
|
|
244 | didn't exist and "O_CREAT" has been given, just like perl's |
|
|
245 | "sysopen", except that it is mandatory (i.e. use 0 if you don't |
|
|
246 | create new files, and 0666 or 0777 if you do). |
|
|
247 | |
|
|
248 | Example: |
|
|
249 | |
|
|
250 | aio_open "/etc/passwd", O_RDONLY, 0, sub { |
|
|
251 | if ($_[0]) { |
|
|
252 | print "open successful, fh is $_[0]\n"; |
|
|
253 | ... |
|
|
254 | } else { |
|
|
255 | die "open failed: $!\n"; |
|
|
256 | } |
|
|
257 | }; |
|
|
258 | |
|
|
259 | aio_close $fh, $callback->($status) |
|
|
260 | Asynchronously close a file and call the callback with the result |
|
|
261 | code. *WARNING:* although accepted, you should not pass in a perl |
|
|
262 | filehandle here, as perl will likely close the file descriptor |
|
|
263 | another time when the filehandle is destroyed. Normally, you can |
|
|
264 | safely call perls "close" or just let filehandles go out of scope. |
|
|
265 | |
|
|
266 | This is supposed to be a bug in the API, so that might change. It's |
|
|
267 | therefore best to avoid this function. |
|
|
268 | |
|
|
269 | aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
|
|
270 | aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval) |
|
|
271 | Reads or writes "length" bytes from the specified "fh" and "offset" |
|
|
272 | into the scalar given by "data" and offset "dataoffset" and calls |
|
|
273 | the callback without the actual number of bytes read (or -1 on |
|
|
274 | error, just like the syscall). |
|
|
275 | |
|
|
276 | The $data scalar *MUST NOT* be modified in any way while the request |
|
|
277 | is outstanding. Modifying it can result in segfaults or WW3 (if the |
|
|
278 | necessary/optional hardware is installed). |
|
|
279 | |
|
|
280 | Example: Read 15 bytes at offset 7 into scalar $buffer, starting at |
|
|
281 | offset 0 within the scalar: |
|
|
282 | |
|
|
283 | aio_read $fh, 7, 15, $buffer, 0, sub { |
|
|
284 | $_[0] > 0 or die "read error: $!"; |
|
|
285 | print "read $_[0] bytes: <$buffer>\n"; |
|
|
286 | }; |
|
|
287 | |
|
|
288 | aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval) |
|
|
289 | Tries to copy $length bytes from $in_fh to $out_fh. It starts |
|
|
290 | reading at byte offset $in_offset, and starts writing at the current |
|
|
291 | file offset of $out_fh. Because of that, it is not safe to issue |
|
|
292 | more than one "aio_sendfile" per $out_fh, as they will interfere |
|
|
293 | with each other. |
|
|
294 | |
|
|
295 | This call tries to make use of a native "sendfile" syscall to |
|
|
296 | provide zero-copy operation. For this to work, $out_fh should refer |
|
|
297 | to a socket, and $in_fh should refer to mmap'able file. |
|
|
298 | |
|
|
299 | If the native sendfile call fails or is not implemented, it will be |
|
|
300 | emulated, so you can call "aio_sendfile" on any type of filehandle |
|
|
301 | regardless of the limitations of the operating system. |
|
|
302 | |
|
|
303 | Please note, however, that "aio_sendfile" can read more bytes from |
|
|
304 | $in_fh than are written, and there is no way to find out how many |
|
|
305 | bytes have been read from "aio_sendfile" alone, as "aio_sendfile" |
|
|
306 | only provides the number of bytes written to $out_fh. Only if the |
|
|
307 | result value equals $length one can assume that $length bytes have |
|
|
308 | been read. |
|
|
309 | |
|
|
310 | aio_readahead $fh,$offset,$length, $callback->($retval) |
|
|
311 | "aio_readahead" populates the page cache with data from a file so |
|
|
312 | that subsequent reads from that file will not block on disk I/O. The |
|
|
313 | $offset argument specifies the starting point from which data is to |
|
|
314 | be read and $length specifies the number of bytes to be read. I/O is |
|
|
315 | performed in whole pages, so that offset is effectively rounded down |
|
|
316 | to a page boundary and bytes are read up to the next page boundary |
|
|
317 | greater than or equal to (off-set+length). "aio_readahead" does not |
|
|
318 | read beyond the end of the file. The current file offset of the file |
|
|
319 | is left unchanged. |
|
|
320 | |
|
|
321 | If that syscall doesn't exist (likely if your OS isn't Linux) it |
|
|
322 | will be emulated by simply reading the data, which would have a |
|
|
323 | similar effect. |
|
|
324 | |
|
|
325 | aio_stat $fh_or_path, $callback->($status) |
|
|
326 | aio_lstat $fh, $callback->($status) |
|
|
327 | Works like perl's "stat" or "lstat" in void context. The callback |
|
|
328 | will be called after the stat and the results will be available |
|
|
329 | using "stat _" or "-s _" etc... |
|
|
330 | |
|
|
331 | The pathname passed to "aio_stat" must be absolute. See API NOTES, |
|
|
332 | above, for an explanation. |
|
|
333 | |
|
|
334 | Currently, the stats are always 64-bit-stats, i.e. instead of |
|
|
335 | returning an error when stat'ing a large file, the results will be |
|
|
336 | silently truncated unless perl itself is compiled with large file |
|
|
337 | support. |
|
|
338 | |
|
|
339 | Example: Print the length of /etc/passwd: |
|
|
340 | |
|
|
341 | aio_stat "/etc/passwd", sub { |
|
|
342 | $_[0] and die "stat failed: $!"; |
|
|
343 | print "size is ", -s _, "\n"; |
|
|
344 | }; |
|
|
345 | |
|
|
346 | aio_unlink $pathname, $callback->($status) |
|
|
347 | Asynchronously unlink (delete) a file and call the callback with the |
|
|
348 | result code. |
|
|
349 | |
|
|
350 | aio_mknod $path, $mode, $dev, $callback->($status) |
|
|
351 | [EXPERIMENTAL] |
|
|
352 | |
|
|
353 | Asynchronously create a device node (or fifo). See mknod(2). |
|
|
354 | |
|
|
355 | The only (POSIX-) portable way of calling this function is: |
|
|
356 | |
|
|
357 | aio_mknod $path, IO::AIO::S_IFIFO | $mode, 0, sub { ... |
|
|
358 | |
|
|
359 | aio_link $srcpath, $dstpath, $callback->($status) |
|
|
360 | Asynchronously create a new link to the existing object at $srcpath |
|
|
361 | at the path $dstpath and call the callback with the result code. |
|
|
362 | |
|
|
363 | aio_symlink $srcpath, $dstpath, $callback->($status) |
|
|
364 | Asynchronously create a new symbolic link to the existing object at |
|
|
365 | $srcpath at the path $dstpath and call the callback with the result |
|
|
366 | code. |
|
|
367 | |
|
|
368 | aio_readlink $path, $callback->($link) |
|
|
369 | Asynchronously read the symlink specified by $path and pass it to |
|
|
370 | the callback. If an error occurs, nothing or undef gets passed to |
|
|
371 | the callback. |
|
|
372 | |
|
|
373 | aio_rename $srcpath, $dstpath, $callback->($status) |
|
|
374 | Asynchronously rename the object at $srcpath to $dstpath, just as |
|
|
375 | rename(2) and call the callback with the result code. |
|
|
376 | |
|
|
377 | aio_rmdir $pathname, $callback->($status) |
|
|
378 | Asynchronously rmdir (delete) a directory and call the callback with |
|
|
379 | the result code. |
|
|
380 | |
|
|
381 | aio_readdir $pathname, $callback->($entries) |
|
|
382 | Unlike the POSIX call of the same name, "aio_readdir" reads an |
|
|
383 | entire directory (i.e. opendir + readdir + closedir). The entries |
|
|
384 | will not be sorted, and will NOT include the "." and ".." entries. |
|
|
385 | |
|
|
386 | The callback a single argument which is either "undef" or an |
|
|
387 | array-ref with the filenames. |
|
|
388 | |
|
|
389 | aio_copy $srcpath, $dstpath, $callback->($status) |
|
|
390 | Try to copy the *file* (directories not supported as either source |
|
|
391 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
392 | the 0 (error) or -1 ok. |
|
|
393 | |
|
|
394 | This is a composite request that it creates the destination file |
|
|
395 | with mode 0200 and copies the contents of the source file into it |
|
|
396 | using "aio_sendfile", followed by restoring atime, mtime, access |
|
|
397 | mode and uid/gid, in that order. |
|
|
398 | |
|
|
399 | If an error occurs, the partial destination file will be unlinked, |
|
|
400 | if possible, except when setting atime, mtime, access mode and |
|
|
401 | uid/gid, where errors are being ignored. |
|
|
402 | |
|
|
403 | aio_move $srcpath, $dstpath, $callback->($status) |
|
|
404 | Try to move the *file* (directories not supported as either source |
|
|
405 | or destination) from $srcpath to $dstpath and call the callback with |
|
|
406 | the 0 (error) or -1 ok. |
|
|
407 | |
|
|
408 | This is a composite request that tries to rename(2) the file first. |
|
|
409 | If rename files with "EXDEV", it copies the file with "aio_copy" |
|
|
410 | and, if that is successful, unlinking the $srcpath. |
|
|
411 | |
|
|
412 | aio_scandir $path, $maxreq, $callback->($dirs, $nondirs) |
|
|
413 | Scans a directory (similar to "aio_readdir") but additionally tries |
|
|
414 | to efficiently separate the entries of directory $path into two sets |
|
|
415 | of names, directories you can recurse into (directories), and ones |
|
|
416 | you cannot recurse into (everything else, including symlinks to |
|
|
417 | directories). |
|
|
418 | |
|
|
419 | "aio_scandir" is a composite request that creates of many sub |
|
|
420 | requests_ $maxreq specifies the maximum number of outstanding aio |
|
|
421 | requests that this function generates. If it is "<= 0", then a |
|
|
422 | suitable default will be chosen (currently 4). |
|
|
423 | |
|
|
424 | On error, the callback is called without arguments, otherwise it |
|
|
425 | receives two array-refs with path-relative entry names. |
|
|
426 | |
|
|
427 | Example: |
|
|
428 | |
|
|
429 | aio_scandir $dir, 0, sub { |
|
|
430 | my ($dirs, $nondirs) = @_; |
|
|
431 | print "real directories: @$dirs\n"; |
|
|
432 | print "everything else: @$nondirs\n"; |
|
|
433 | }; |
|
|
434 | |
|
|
435 | Implementation notes. |
|
|
436 | |
|
|
437 | The "aio_readdir" cannot be avoided, but "stat()"'ing every entry |
|
|
438 | can. |
|
|
439 | |
|
|
440 | After reading the directory, the modification time, size etc. of the |
|
|
441 | directory before and after the readdir is checked, and if they match |
|
|
442 | (and isn't the current time), the link count will be used to decide |
|
|
443 | how many entries are directories (if >= 2). Otherwise, no knowledge |
|
|
444 | of the number of subdirectories will be assumed. |
|
|
445 | |
|
|
446 | Then entries will be sorted into likely directories (everything |
|
|
447 | without a non-initial dot currently) and likely non-directories |
|
|
448 | (everything else). Then every entry plus an appended "/." will be |
|
|
449 | "stat"'ed, likely directories first. If that succeeds, it assumes |
|
|
450 | that the entry is a directory or a symlink to directory (which will |
|
|
451 | be checked seperately). This is often faster than stat'ing the entry |
|
|
452 | itself because filesystems might detect the type of the entry |
|
|
453 | without reading the inode data (e.g. ext2fs filetype feature). |
|
|
454 | |
|
|
455 | If the known number of directories (link count - 2) has been |
|
|
456 | reached, the rest of the entries is assumed to be non-directories. |
|
|
457 | |
|
|
458 | This only works with certainty on POSIX (= UNIX) filesystems, which |
|
|
459 | fortunately are the vast majority of filesystems around. |
|
|
460 | |
|
|
461 | It will also likely work on non-POSIX filesystems with reduced |
|
|
462 | efficiency as those tend to return 0 or 1 as link counts, which |
|
|
463 | disables the directory counting heuristic. |
|
|
464 | |
|
|
465 | aio_fsync $fh, $callback->($status) |
|
|
466 | Asynchronously call fsync on the given filehandle and call the |
|
|
467 | callback with the fsync result code. |
|
|
468 | |
|
|
469 | aio_fdatasync $fh, $callback->($status) |
|
|
470 | Asynchronously call fdatasync on the given filehandle and call the |
|
|
471 | callback with the fdatasync result code. |
|
|
472 | |
|
|
473 | If this call isn't available because your OS lacks it or it couldn't |
|
|
474 | be detected, it will be emulated by calling "fsync" instead. |
|
|
475 | |
|
|
476 | aio_group $callback->(...) |
|
|
477 | This is a very special aio request: Instead of doing something, it |
|
|
478 | is a container for other aio requests, which is useful if you want |
|
|
479 | to bundle many requests into a single, composite, request with a |
|
|
480 | definite callback and the ability to cancel the whole request with |
|
|
481 | its subrequests. |
|
|
482 | |
|
|
483 | Returns an object of class IO::AIO::GRP. See its documentation below |
|
|
484 | for more info. |
|
|
485 | |
|
|
486 | Example: |
|
|
487 | |
|
|
488 | my $grp = aio_group sub { |
|
|
489 | print "all stats done\n"; |
|
|
490 | }; |
|
|
491 | |
|
|
492 | add $grp |
|
|
493 | (aio_stat ...), |
|
|
494 | (aio_stat ...), |
|
|
495 | ...; |
|
|
496 | |
|
|
497 | aio_nop $callback->() |
|
|
498 | This is a special request - it does nothing in itself and is only |
|
|
499 | used for side effects, such as when you want to add a dummy request |
|
|
500 | to a group so that finishing the requests in the group depends on |
|
|
501 | executing the given code. |
|
|
502 | |
|
|
503 | While this request does nothing, it still goes through the execution |
|
|
504 | phase and still requires a worker thread. Thus, the callback will |
|
|
505 | not be executed immediately but only after other requests in the |
|
|
506 | queue have entered their execution phase. This can be used to |
|
|
507 | measure request latency. |
|
|
508 | |
|
|
509 | IO::AIO::aio_busy $fractional_seconds, $callback->() *NOT EXPORTED* |
|
|
510 | Mainly used for debugging and benchmarking, this aio request puts |
|
|
511 | one of the request workers to sleep for the given time. |
|
|
512 | |
|
|
513 | While it is theoretically handy to have simple I/O scheduling |
|
|
514 | requests like sleep and file handle readable/writable, the overhead |
|
|
515 | this creates is immense (it blocks a thread for a long time) so do |
|
|
516 | not use this function except to put your application under |
|
|
517 | artificial I/O pressure. |
|
|
518 | |
|
|
519 | IO::AIO::REQ CLASS |
|
|
520 | All non-aggregate "aio_*" functions return an object of this class when |
|
|
521 | called in non-void context. |
|
|
522 | |
|
|
523 | cancel $req |
|
|
524 | Cancels the request, if possible. Has the effect of skipping |
|
|
525 | execution when entering the execute state and skipping calling the |
|
|
526 | callback when entering the the result state, but will leave the |
|
|
527 | request otherwise untouched. That means that requests that currently |
|
|
528 | execute will not be stopped and resources held by the request will |
|
|
529 | not be freed prematurely. |
|
|
530 | |
|
|
531 | cb $req $callback->(...) |
|
|
532 | Replace (or simply set) the callback registered to the request. |
|
|
533 | |
|
|
534 | IO::AIO::GRP CLASS |
|
|
535 | This class is a subclass of IO::AIO::REQ, so all its methods apply to |
|
|
536 | objects of this class, too. |
|
|
537 | |
|
|
538 | A IO::AIO::GRP object is a special request that can contain multiple |
|
|
539 | other aio requests. |
|
|
540 | |
|
|
541 | You create one by calling the "aio_group" constructing function with a |
|
|
542 | callback that will be called when all contained requests have entered |
|
|
543 | the "done" state: |
|
|
544 | |
|
|
545 | my $grp = aio_group sub { |
|
|
546 | print "all requests are done\n"; |
|
|
547 | }; |
|
|
548 | |
|
|
549 | You add requests by calling the "add" method with one or more |
|
|
550 | "IO::AIO::REQ" objects: |
|
|
551 | |
|
|
552 | $grp->add (aio_unlink "..."); |
|
|
553 | |
|
|
554 | add $grp aio_stat "...", sub { |
|
|
555 | $_[0] or return $grp->result ("error"); |
|
|
556 | |
|
|
557 | # add another request dynamically, if first succeeded |
|
|
558 | add $grp aio_open "...", sub { |
|
|
559 | $grp->result ("ok"); |
|
|
560 | }; |
|
|
561 | }; |
|
|
562 | |
573 | This makes it very easy to create composite requests (see the source |
563 | This makes it very easy to create composite requests (see the source of |
574 | of "aio_move" for an application) that work and feel like simple |
564 | "aio_move" for an application) that work and feel like simple requests. |
575 | requests. |
|
|
576 | |
565 | |
577 | * The IO::AIO::GRP objects will be cleaned up during calls to |
566 | * The IO::AIO::GRP objects will be cleaned up during calls to |
578 | "IO::AIO::poll_cb", just like any other request. |
567 | "IO::AIO::poll_cb", just like any other request. |
579 | * They can be canceled like any other request. Canceling will cancel |
568 | * They can be canceled like any other request. Canceling will cancel not |
580 | not only the request itself, but also all requests it contains. |
569 | only the request itself, but also all requests it contains. |
581 | * They can also can also be added to other IO::AIO::GRP objects. |
570 | * They can also can also be added to other IO::AIO::GRP objects. |
582 | * You must not add requests to a group from within the group |
571 | * You must not add requests to a group from within the group callback |
583 | callback (or any later time). |
572 | (or any later time). |
584 | |
573 | |
585 | Their lifetime, simplified, looks like this: when they are empty, |
574 | Their lifetime, simplified, looks like this: when they are empty, they |
586 | they will finish very quickly. If they contain only requests that |
575 | will finish very quickly. If they contain only requests that are in the |
587 | are in the "done" state, they will also finish. Otherwise they will |
576 | "done" state, they will also finish. Otherwise they will continue to |
588 | continue to exist. |
577 | exist. |
589 | |
578 | |
590 | That means after creating a group you have some time to add |
579 | That means after creating a group you have some time to add requests. |
591 | requests. And in the callbacks of those requests, you can add |
580 | And in the callbacks of those requests, you can add further requests to |
592 | further requests to the group. And only when all those requests have |
581 | the group. And only when all those requests have finished will the the |
593 | finished will the the group itself finish. |
582 | group itself finish. |
594 | |
583 | |
595 | add $grp ... |
584 | add $grp ... |
596 | $grp->add (...) |
585 | $grp->add (...) |
597 | Add one or more requests to the group. Any type of IO::AIO::REQ |
586 | Add one or more requests to the group. Any type of IO::AIO::REQ can |
598 | can be added, including other groups, as long as you do not |
587 | be added, including other groups, as long as you do not create |
599 | create circular dependencies. |
588 | circular dependencies. |
600 | |
589 | |
601 | Returns all its arguments. |
590 | Returns all its arguments. |
602 | |
591 | |
603 | $grp->cancel_subs |
592 | $grp->cancel_subs |
604 | Cancel all subrequests and clears any feeder, but not the group |
593 | Cancel all subrequests and clears any feeder, but not the group |
605 | request itself. Useful when you queued a lot of events but got a |
594 | request itself. Useful when you queued a lot of events but got a |
606 | result early. |
595 | result early. |
607 | |
596 | |
608 | $grp->result (...) |
597 | $grp->result (...) |
609 | Set the result value(s) that will be passed to the group |
598 | Set the result value(s) that will be passed to the group callback |
610 | callback when all subrequests have finished and set thre groups |
599 | when all subrequests have finished and set thre groups errno to the |
611 | errno to the current value of errno (just like calling "errno" |
600 | current value of errno (just like calling "errno" without an error |
612 | without an error number). By default, no argument will be passed |
601 | number). By default, no argument will be passed and errno is zero. |
613 | and errno is zero. |
|
|
614 | |
602 | |
615 | $grp->errno ([$errno]) |
603 | $grp->errno ([$errno]) |
616 | Sets the group errno value to $errno, or the current value of |
604 | Sets the group errno value to $errno, or the current value of errno |
617 | errno when the argument is missing. |
605 | when the argument is missing. |
618 | |
606 | |
619 | Every aio request has an associated errno value that is restored |
607 | Every aio request has an associated errno value that is restored |
620 | when the callback is invoked. This method lets you change this |
608 | when the callback is invoked. This method lets you change this value |
621 | value from its default (0). |
609 | from its default (0). |
622 | |
610 | |
623 | Calling "result" will also set errno, so make sure you either |
611 | Calling "result" will also set errno, so make sure you either set $! |
624 | set $! before the call to "result", or call c<errno> after it. |
612 | before the call to "result", or call c<errno> after it. |
625 | |
613 | |
626 | feed $grp $callback->($grp) |
614 | feed $grp $callback->($grp) |
627 | Sets a feeder/generator on this group: every group can have an |
615 | Sets a feeder/generator on this group: every group can have an |
628 | attached generator that generates requests if idle. The idea |
616 | attached generator that generates requests if idle. The idea behind |
629 | behind this is that, although you could just queue as many |
617 | this is that, although you could just queue as many requests as you |
630 | requests as you want in a group, this might starve other |
618 | want in a group, this might starve other requests for a potentially |
631 | requests for a potentially long time. For example, "aio_scandir" |
619 | long time. For example, "aio_scandir" might generate hundreds of |
632 | might generate hundreds of thousands "aio_stat" requests, |
620 | thousands "aio_stat" requests, delaying any later requests for a |
633 | delaying any later requests for a long time. |
621 | long time. |
634 | |
622 | |
635 | To avoid this, and allow incremental generation of requests, you |
623 | To avoid this, and allow incremental generation of requests, you can |
636 | can instead a group and set a feeder on it that generates those |
624 | instead a group and set a feeder on it that generates those |
637 | requests. The feed callback will be called whenever there are |
625 | requests. The feed callback will be called whenever there are few |
638 | few enough (see "limit", below) requests active in the group |
626 | enough (see "limit", below) requests active in the group itself and |
639 | itself and is expected to queue more requests. |
627 | is expected to queue more requests. |
640 | |
628 | |
641 | The feed callback can queue as many requests as it likes (i.e. |
629 | The feed callback can queue as many requests as it likes (i.e. "add" |
642 | "add" does not impose any limits). |
630 | does not impose any limits). |
643 | |
631 | |
644 | If the feed does not queue more requests when called, it will be |
632 | If the feed does not queue more requests when called, it will be |
645 | automatically removed from the group. |
633 | automatically removed from the group. |
646 | |
634 | |
647 | If the feed limit is 0, it will be set to 2 automatically. |
635 | If the feed limit is 0, it will be set to 2 automatically. |
648 | |
636 | |
649 | Example: |
637 | Example: |
650 | |
638 | |
651 | # stat all files in @files, but only ever use four aio requests concurrently: |
639 | # stat all files in @files, but only ever use four aio requests concurrently: |
652 | |
640 | |
653 | my $grp = aio_group sub { print "finished\n" }; |
641 | my $grp = aio_group sub { print "finished\n" }; |
654 | limit $grp 4; |
642 | limit $grp 4; |
655 | feed $grp sub { |
643 | feed $grp sub { |
656 | my $file = pop @files |
644 | my $file = pop @files |
657 | or return; |
645 | or return; |
658 | |
646 | |
659 | add $grp aio_stat $file, sub { ... }; |
647 | add $grp aio_stat $file, sub { ... }; |
660 | }; |
648 | }; |
661 | |
649 | |
662 | limit $grp $num |
650 | limit $grp $num |
663 | Sets the feeder limit for the group: The feeder will be called |
651 | Sets the feeder limit for the group: The feeder will be called |
664 | whenever the group contains less than this many requests. |
652 | whenever the group contains less than this many requests. |
665 | |
653 | |
666 | Setting the limit to 0 will pause the feeding process. |
654 | Setting the limit to 0 will pause the feeding process. |
667 | |
655 | |
668 | SUPPORT FUNCTIONS |
656 | SUPPORT FUNCTIONS |
669 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
657 | EVENT PROCESSING AND EVENT LOOP INTEGRATION |
670 | $fileno = IO::AIO::poll_fileno |
658 | $fileno = IO::AIO::poll_fileno |
671 | Return the *request result pipe file descriptor*. This |
659 | Return the *request result pipe file descriptor*. This filehandle |
672 | filehandle must be polled for reading by some mechanism outside |
660 | must be polled for reading by some mechanism outside this module |
673 | this module (e.g. Event or select, see below or the SYNOPSIS). |
661 | (e.g. Event or select, see below or the SYNOPSIS). If the pipe |
674 | If the pipe becomes readable you have to call "poll_cb" to check |
662 | becomes readable you have to call "poll_cb" to check the results. |
675 | the results. |
|
|
676 | |
663 | |
677 | See "poll_cb" for an example. |
664 | See "poll_cb" for an example. |
678 | |
665 | |
679 | IO::AIO::poll_cb |
666 | IO::AIO::poll_cb |
680 | Process some outstanding events on the result pipe. You have to |
667 | Process some outstanding events on the result pipe. You have to call |
681 | call this regularly. Returns the number of events processed. |
668 | this regularly. Returns the number of events processed. Returns |
682 | Returns immediately when no events are outstanding. The amount |
669 | immediately when no events are outstanding. The amount of events |
683 | of events processed depends on the settings of |
670 | processed depends on the settings of "IO::AIO::max_poll_req" and |
684 | "IO::AIO::max_poll_req" and "IO::AIO::max_poll_time". |
671 | "IO::AIO::max_poll_time". |
685 | |
672 | |
686 | If not all requests were processed for whatever reason, the |
673 | If not all requests were processed for whatever reason, the |
687 | filehandle will still be ready when "poll_cb" returns. |
674 | filehandle will still be ready when "poll_cb" returns. |
688 | |
675 | |
689 | Example: Install an Event watcher that automatically calls |
676 | Example: Install an Event watcher that automatically calls |
690 | IO::AIO::poll_cb with high priority: |
677 | IO::AIO::poll_cb with high priority: |
691 | |
678 | |
692 | Event->io (fd => IO::AIO::poll_fileno, |
679 | Event->io (fd => IO::AIO::poll_fileno, |
693 | poll => 'r', async => 1, |
680 | poll => 'r', async => 1, |
694 | cb => \&IO::AIO::poll_cb); |
681 | cb => \&IO::AIO::poll_cb); |
695 | |
682 | |
696 | IO::AIO::max_poll_reqs $nreqs |
683 | IO::AIO::max_poll_reqs $nreqs |
697 | IO::AIO::max_poll_time $seconds |
684 | IO::AIO::max_poll_time $seconds |
698 | These set the maximum number of requests (default 0, meaning |
685 | These set the maximum number of requests (default 0, meaning |
699 | infinity) that are being processed by "IO::AIO::poll_cb" in one |
686 | infinity) that are being processed by "IO::AIO::poll_cb" in one |
700 | call, respectively the maximum amount of time (default 0, |
687 | call, respectively the maximum amount of time (default 0, meaning |
701 | meaning infinity) spent in "IO::AIO::poll_cb" to process |
688 | infinity) spent in "IO::AIO::poll_cb" to process requests (more |
702 | requests (more correctly the mininum amount of time "poll_cb" is |
689 | correctly the mininum amount of time "poll_cb" is allowed to use). |
703 | allowed to use). |
|
|
704 | |
690 | |
|
|
691 | Setting "max_poll_time" to a non-zero value creates an overhead of |
|
|
692 | one syscall per request processed, which is not normally a problem |
|
|
693 | unless your callbacks are really really fast or your OS is really |
|
|
694 | really slow (I am not mentioning Solaris here). Using |
|
|
695 | "max_poll_reqs" incurs no overhead. |
|
|
696 | |
705 | Setting these is useful if you want to ensure some level of |
697 | Setting these is useful if you want to ensure some level of |
706 | interactiveness when perl is not fast enough to process all |
698 | interactiveness when perl is not fast enough to process all requests |
707 | requests in time. |
699 | in time. |
708 | |
700 | |
709 | For interactive programs, values such as 0.01 to 0.1 should be |
701 | For interactive programs, values such as 0.01 to 0.1 should be fine. |
710 | fine. |
|
|
711 | |
702 | |
712 | Example: Install an Event watcher that automatically calls |
703 | Example: Install an Event watcher that automatically calls |
713 | IO::AIO::poll_some with low priority, to ensure that other parts |
704 | IO::AIO::poll_cb with low priority, to ensure that other parts of |
714 | of the program get the CPU sometimes even under high AIO load. |
705 | the program get the CPU sometimes even under high AIO load. |
715 | |
706 | |
716 | # try not to spend much more than 0.1s in poll_cb |
707 | # try not to spend much more than 0.1s in poll_cb |
717 | IO::AIO::max_poll_time 0.1; |
708 | IO::AIO::max_poll_time 0.1; |
718 | |
709 | |
719 | # use a low priority so other tasks have priority |
710 | # use a low priority so other tasks have priority |
720 | Event->io (fd => IO::AIO::poll_fileno, |
711 | Event->io (fd => IO::AIO::poll_fileno, |
721 | poll => 'r', nice => 1, |
712 | poll => 'r', nice => 1, |
722 | cb => &IO::AIO::poll_cb); |
713 | cb => &IO::AIO::poll_cb); |
723 | |
714 | |
724 | IO::AIO::poll_wait |
715 | IO::AIO::poll_wait |
725 | Wait till the result filehandle becomes ready for reading |
716 | Wait till the result filehandle becomes ready for reading (simply |
726 | (simply does a "select" on the filehandle. This is useful if you |
717 | does a "select" on the filehandle. This is useful if you want to |
727 | want to synchronously wait for some requests to finish). |
718 | synchronously wait for some requests to finish). |
728 | |
719 | |
729 | See "nreqs" for an example. |
720 | See "nreqs" for an example. |
730 | |
721 | |
731 | IO::AIO::poll |
722 | IO::AIO::poll |
732 | Waits until some requests have been handled. |
723 | Waits until some requests have been handled. |
733 | |
724 | |
734 | Strictly equivalent to: |
725 | Strictly equivalent to: |
735 | |
726 | |
736 | IO::AIO::poll_wait, IO::AIO::poll_cb |
727 | IO::AIO::poll_wait, IO::AIO::poll_cb |
737 | if IO::AIO::nreqs; |
728 | if IO::AIO::nreqs; |
738 | |
729 | |
739 | IO::AIO::flush |
730 | IO::AIO::flush |
740 | Wait till all outstanding AIO requests have been handled. |
731 | Wait till all outstanding AIO requests have been handled. |
741 | |
732 | |
742 | Strictly equivalent to: |
733 | Strictly equivalent to: |
743 | |
734 | |
744 | IO::AIO::poll_wait, IO::AIO::poll_cb |
735 | IO::AIO::poll_wait, IO::AIO::poll_cb |
745 | while IO::AIO::nreqs; |
736 | while IO::AIO::nreqs; |
746 | |
737 | |
747 | CONTROLLING THE NUMBER OF THREADS |
738 | CONTROLLING THE NUMBER OF THREADS |
748 | IO::AIO::min_parallel $nthreads |
739 | IO::AIO::min_parallel $nthreads |
749 | Set the minimum number of AIO threads to $nthreads. The current |
740 | Set the minimum number of AIO threads to $nthreads. The current |
750 | default is 8, which means eight asynchronous operations can |
741 | default is 8, which means eight asynchronous operations can execute |
751 | execute concurrently at any one time (the number of outstanding |
742 | concurrently at any one time (the number of outstanding requests, |
752 | requests, however, is unlimited). |
743 | however, is unlimited). |
753 | |
744 | |
754 | IO::AIO starts threads only on demand, when an AIO request is |
745 | IO::AIO starts threads only on demand, when an AIO request is queued |
755 | queued and no free thread exists. Please note that queueing up a |
746 | and no free thread exists. Please note that queueing up a hundred |
756 | hundred requests can create demand for a hundred threads, even |
747 | requests can create demand for a hundred threads, even if it turns |
757 | if it turns out that everything is in the cache and could have |
748 | out that everything is in the cache and could have been processed |
758 | been processed faster by a single thread. |
749 | faster by a single thread. |
759 | |
750 | |
760 | It is recommended to keep the number of threads relatively low, |
751 | It is recommended to keep the number of threads relatively low, as |
761 | as some Linux kernel versions will scale negatively with the |
752 | some Linux kernel versions will scale negatively with the number of |
762 | number of threads (higher parallelity => MUCH higher latency). |
753 | threads (higher parallelity => MUCH higher latency). With current |
763 | With current Linux 2.6 versions, 4-32 threads should be fine. |
754 | Linux 2.6 versions, 4-32 threads should be fine. |
764 | |
755 | |
765 | Under most circumstances you don't need to call this function, |
756 | Under most circumstances you don't need to call this function, as |
766 | as the module selects a default that is suitable for low to |
757 | the module selects a default that is suitable for low to moderate |
767 | moderate load. |
758 | load. |
768 | |
759 | |
769 | IO::AIO::max_parallel $nthreads |
760 | IO::AIO::max_parallel $nthreads |
770 | Sets the maximum number of AIO threads to $nthreads. If more |
761 | Sets the maximum number of AIO threads to $nthreads. If more than |
771 | than the specified number of threads are currently running, this |
762 | the specified number of threads are currently running, this function |
772 | function kills them. This function blocks until the limit is |
763 | kills them. This function blocks until the limit is reached. |
773 | reached. |
|
|
774 | |
764 | |
775 | While $nthreads are zero, aio requests get queued but not |
765 | While $nthreads are zero, aio requests get queued but not executed |
776 | executed until the number of threads has been increased again. |
766 | until the number of threads has been increased again. |
777 | |
767 | |
778 | This module automatically runs "max_parallel 0" at program end, |
768 | This module automatically runs "max_parallel 0" at program end, to |
779 | to ensure that all threads are killed and that there are no |
769 | ensure that all threads are killed and that there are no outstanding |
780 | outstanding requests. |
770 | requests. |
781 | |
771 | |
782 | Under normal circumstances you don't need to call this function. |
772 | Under normal circumstances you don't need to call this function. |
783 | |
773 | |
784 | IO::AIO::max_idle $nthreads |
774 | IO::AIO::max_idle $nthreads |
785 | Limit the number of threads (default: 4) that are allowed to |
775 | Limit the number of threads (default: 4) that are allowed to idle |
786 | idle (i.e., threads that did not get a request to process within |
776 | (i.e., threads that did not get a request to process within 10 |
787 | 10 seconds). That means if a thread becomes idle while $nthreads |
777 | seconds). That means if a thread becomes idle while $nthreads other |
788 | other threads are also idle, it will free its resources and |
778 | threads are also idle, it will free its resources and exit. |
789 | exit. |
|
|
790 | |
779 | |
791 | This is useful when you allow a large number of threads (e.g. |
780 | This is useful when you allow a large number of threads (e.g. 100 or |
792 | 100 or 1000) to allow for extremely high load situations, but |
781 | 1000) to allow for extremely high load situations, but want to free |
793 | want to free resources under normal circumstances (1000 threads |
782 | resources under normal circumstances (1000 threads can easily |
794 | can easily consume 30MB of RAM). |
783 | consume 30MB of RAM). |
795 | |
784 | |
796 | The default is probably ok in most situations, especially if |
785 | The default is probably ok in most situations, especially if thread |
797 | thread creation is fast. If thread creation is very slow on your |
786 | creation is fast. If thread creation is very slow on your system you |
798 | system you might want to use larger values. |
787 | might want to use larger values. |
799 | |
788 | |
800 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
789 | $oldmaxreqs = IO::AIO::max_outstanding $maxreqs |
801 | This is a very bad function to use in interactive programs |
790 | This is a very bad function to use in interactive programs because |
802 | because it blocks, and a bad way to reduce concurrency because |
791 | it blocks, and a bad way to reduce concurrency because it is |
803 | it is inexact: Better use an "aio_group" together with a feed |
792 | inexact: Better use an "aio_group" together with a feed callback. |
804 | callback. |
|
|
805 | |
793 | |
806 | Sets the maximum number of outstanding requests to $nreqs. If |
794 | Sets the maximum number of outstanding requests to $nreqs. If you to |
807 | you to queue up more than this number of requests, the next call |
795 | queue up more than this number of requests, the next call to the |
808 | to the "poll_cb" (and "poll_some" and other functions calling |
796 | "poll_cb" (and "poll_some" and other functions calling "poll_cb") |
809 | "poll_cb") function will block until the limit is no longer |
797 | function will block until the limit is no longer exceeded. |
810 | exceeded. |
|
|
811 | |
798 | |
812 | The default value is very large, so there is no practical limit |
799 | The default value is very large, so there is no practical limit on |
813 | on the number of outstanding requests. |
800 | the number of outstanding requests. |
814 | |
801 | |
815 | You can still queue as many requests as you want. Therefore, |
802 | You can still queue as many requests as you want. Therefore, |
816 | "max_oustsanding" is mainly useful in simple scripts (with low |
803 | "max_oustsanding" is mainly useful in simple scripts (with low |
817 | values) or as a stop gap to shield against fatal memory overflow |
804 | values) or as a stop gap to shield against fatal memory overflow |
818 | (with large values). |
805 | (with large values). |
819 | |
806 | |
820 | STATISTICAL INFORMATION |
807 | STATISTICAL INFORMATION |
821 | IO::AIO::nreqs |
808 | IO::AIO::nreqs |
822 | Returns the number of requests currently in the ready, execute |
809 | Returns the number of requests currently in the ready, execute or |
823 | or pending states (i.e. for which their callback has not been |
810 | pending states (i.e. for which their callback has not been invoked |
824 | invoked yet). |
811 | yet). |
825 | |
812 | |
826 | Example: wait till there are no outstanding requests anymore: |
813 | Example: wait till there are no outstanding requests anymore: |
827 | |
814 | |
828 | IO::AIO::poll_wait, IO::AIO::poll_cb |
815 | IO::AIO::poll_wait, IO::AIO::poll_cb |
829 | while IO::AIO::nreqs; |
816 | while IO::AIO::nreqs; |
830 | |
817 | |
831 | IO::AIO::nready |
818 | IO::AIO::nready |
832 | Returns the number of requests currently in the ready state (not |
819 | Returns the number of requests currently in the ready state (not yet |
833 | yet executed). |
820 | executed). |
834 | |
821 | |
835 | IO::AIO::npending |
822 | IO::AIO::npending |
836 | Returns the number of requests currently in the pending state |
823 | Returns the number of requests currently in the pending state |
837 | (executed, but not yet processed by poll_cb). |
824 | (executed, but not yet processed by poll_cb). |
838 | |
825 | |
839 | FORK BEHAVIOUR |
826 | FORK BEHAVIOUR |
840 | This module should do "the right thing" when the process using it |
827 | This module should do "the right thing" when the process using it forks: |
841 | forks: |
|
|
842 | |
828 | |
843 | Before the fork, IO::AIO enters a quiescent state where no requests |
829 | Before the fork, IO::AIO enters a quiescent state where no requests can |
844 | can be added in other threads and no results will be processed. |
830 | be added in other threads and no results will be processed. After the |
845 | After the fork the parent simply leaves the quiescent state and |
831 | fork the parent simply leaves the quiescent state and continues |
846 | continues request/result processing, while the child frees the |
832 | request/result processing, while the child frees the request/result |
847 | request/result queue (so that the requests started before the fork |
833 | queue (so that the requests started before the fork will only be handled |
848 | will only be handled in the parent). Threads will be started on |
834 | in the parent). Threads will be started on demand until the limit set in |
849 | demand until the limit set in the parent process has been reached |
835 | the parent process has been reached again. |
850 | again. |
|
|
851 | |
836 | |
852 | In short: the parent will, after a short pause, continue as if fork |
837 | In short: the parent will, after a short pause, continue as if fork had |
853 | had not been called, while the child will act as if IO::AIO has not |
838 | not been called, while the child will act as if IO::AIO has not been |
854 | been used yet. |
839 | used yet. |
855 | |
840 | |
856 | MEMORY USAGE |
841 | MEMORY USAGE |
857 | Per-request usage: |
842 | Per-request usage: |
858 | |
843 | |
859 | Each aio request uses - depending on your architecture - around |
844 | Each aio request uses - depending on your architecture - around 100-200 |
860 | 100-200 bytes of memory. In addition, stat requests need a stat |
845 | bytes of memory. In addition, stat requests need a stat buffer (possibly |
861 | buffer (possibly a few hundred bytes), readdir requires a result |
846 | a few hundred bytes), readdir requires a result buffer and so on. Perl |
862 | buffer and so on. Perl scalars and other data passed into aio |
847 | scalars and other data passed into aio requests will also be locked and |
863 | requests will also be locked and will consume memory till the |
848 | will consume memory till the request has entered the done state. |
864 | request has entered the done state. |
|
|
865 | |
849 | |
866 | This is now awfully much, so queuing lots of requests is not usually |
850 | This is now awfully much, so queuing lots of requests is not usually a |
867 | a problem. |
851 | problem. |
868 | |
852 | |
869 | Per-thread usage: |
853 | Per-thread usage: |
870 | |
854 | |
871 | In the execution phase, some aio requests require more memory for |
855 | In the execution phase, some aio requests require more memory for |
872 | temporary buffers, and each thread requires a stack and other data |
856 | temporary buffers, and each thread requires a stack and other data |
873 | structures (usually around 16k-128k, depending on the OS). |
857 | structures (usually around 16k-128k, depending on the OS). |
874 | |
858 | |
875 | KNOWN BUGS |
859 | KNOWN BUGS |
876 | Known bugs will be fixed in the next release. |
860 | Known bugs will be fixed in the next release. |
877 | |
861 | |
878 | SEE ALSO |
862 | SEE ALSO |
879 | Coro::AIO. |
863 | Coro::AIO. |
880 | |
864 | |
881 | AUTHOR |
865 | AUTHOR |
882 | Marc Lehmann <schmorp@schmorp.de> |
866 | Marc Lehmann <schmorp@schmorp.de> |
883 | http://home.schmorp.de/ |
867 | http://home.schmorp.de/ |
884 | |
868 | |