… | |
… | |
124 | =back |
124 | =back |
125 | |
125 | |
126 | For libev, you would typically use an C<ev_async> watcher: the |
126 | For libev, you would typically use an C<ev_async> watcher: the |
127 | C<want_poll> callback would invoke C<ev_async_send> to wake up the event |
127 | C<want_poll> callback would invoke C<ev_async_send> to wake up the event |
128 | loop. Inside the callback set for the watcher, one would call C<eio_poll |
128 | loop. Inside the callback set for the watcher, one would call C<eio_poll |
129 | ()> (followed by C<ev_async_send> again if C<eio_poll> indicates that not |
129 | ()>. |
130 | all requests have been handled yet). The race is taken care of because |
130 | |
131 | libev resets/rearms the async watcher before calling your callback, |
131 | If C<eio_poll ()> is configured to not handle all results in one go |
132 | and therefore, before calling C<eio_poll>. This might result in (some) |
132 | (i.e. it returns C<-1>) then you should start an idle watcher that calls |
133 | spurious wake-ups, but is generally harmless. |
133 | C<eio_poll> until it returns something C<!= -1>. |
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134 | |
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135 | A full-featured conenctor between libeio and libev would look as follows |
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136 | (if C<eio_poll> is handling all requests, it can of course be simplified a |
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137 | lot by removing the idle watcher logic): |
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138 | |
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139 | static struct ev_loop *loop; |
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140 | static ev_idle repeat_watcher; |
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141 | static ev_async ready_watcher; |
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142 | |
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143 | /* idle watcher callback, only used when eio_poll */ |
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144 | /* didn't handle all results in one call */ |
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145 | static void |
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146 | repeat (EV_P_ ev_idle *w, int revents) |
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147 | { |
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148 | if (eio_poll () != -1) |
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149 | ev_idle_stop (EV_A_ w); |
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150 | } |
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151 | |
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152 | /* eio has some results, process them */ |
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153 | static void |
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154 | ready (EV_P_ ev_async *w, int revents) |
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155 | { |
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156 | if (eio_poll () == -1) |
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157 | ev_idle_start (EV_A_ &repeat_watcher); |
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158 | } |
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159 | |
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160 | /* wake up the event loop */ |
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161 | static void |
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162 | want_poll (void) |
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163 | { |
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164 | ev_async_send (loop, &ready_watcher) |
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165 | } |
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166 | |
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167 | void |
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168 | my_init_eio () |
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169 | { |
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170 | loop = EV_DEFAULT; |
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171 | |
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172 | ev_idle_init (&repeat_watcher, repeat); |
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173 | ev_async_init (&ready_watcher, ready); |
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174 | ev_async_start (loop &watcher); |
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175 | |
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176 | eio_init (want_poll, 0); |
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177 | } |
134 | |
178 | |
135 | For most other event loops, you would typically use a pipe - the event |
179 | For most other event loops, you would typically use a pipe - the event |
136 | loop should be told to wait for read readiness on the read end. In |
180 | loop should be told to wait for read readiness on the read end. In |
137 | C<want_poll> you would write a single byte, in C<done_poll> you would try |
181 | C<want_poll> you would write a single byte, in C<done_poll> you would try |
138 | to read that byte, and in the callback for the read end, you would call |
182 | to read that byte, and in the callback for the read end, you would call |
139 | C<eio_poll>. The race is avoided here because the event loop should invoke |
183 | C<eio_poll>. |
140 | your callback again and again until the byte has been read (as the pipe |
184 | |
141 | read callback does not read it, only C<done_poll>). |
185 | You don't have to take special care in the case C<eio_poll> doesn't handle |
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186 | all requests, as the done callback will not be invoked, so the event loop |
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187 | will still signal readyness for the pipe until I<all> results have been |
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188 | processed. |
142 | |
189 | |
143 | |
190 | |
144 | =head1 HIGH LEVEL REQUEST API |
191 | =head1 HIGH LEVEL REQUEST API |
145 | |
192 | |
146 | Libeio has both a high-level API, which consists of calling a request |
193 | Libeio has both a high-level API, which consists of calling a request |
… | |
… | |
153 | |
200 | |
154 | You submit a request by calling the relevant C<eio_TYPE> function with the |
201 | You submit a request by calling the relevant C<eio_TYPE> function with the |
155 | required parameters, a callback of type C<int (*eio_cb)(eio_req *req)> |
202 | required parameters, a callback of type C<int (*eio_cb)(eio_req *req)> |
156 | (called C<eio_cb> below) and a freely usable C<void *data> argument. |
203 | (called C<eio_cb> below) and a freely usable C<void *data> argument. |
157 | |
204 | |
158 | The return value will either be 0 |
205 | The return value will either be 0, in case something went really wrong |
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206 | (which can basically only happen on very fatal errors, such as C<malloc> |
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207 | returning 0, which is rather unlikely), or a pointer to the newly-created |
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208 | and submitted C<eio_req *>. |
159 | |
209 | |
160 | The callback will be called with an C<eio_req *> which contains the |
210 | The callback will be called with an C<eio_req *> which contains the |
161 | results of the request. The members you can access inside that structure |
211 | results of the request. The members you can access inside that structure |
162 | vary from request to request, except for: |
212 | vary from request to request, except for: |
163 | |
213 | |
… | |
… | |
226 | custom data value as C<data>. |
276 | custom data value as C<data>. |
227 | |
277 | |
228 | =head3 POSIX API WRAPPERS |
278 | =head3 POSIX API WRAPPERS |
229 | |
279 | |
230 | These requests simply wrap the POSIX call of the same name, with the same |
280 | These requests simply wrap the POSIX call of the same name, with the same |
231 | arguments: |
281 | arguments. If a function is not implemented by the OS and cannot be emulated |
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282 | in some way, then all of these return C<-1> and set C<errorno> to C<ENOSYS>. |
232 | |
283 | |
233 | =over 4 |
284 | =over 4 |
234 | |
285 | |
235 | =item eio_open (const char *path, int flags, mode_t mode, int pri, eio_cb cb, void *data) |
286 | =item eio_open (const char *path, int flags, mode_t mode, int pri, eio_cb cb, void *data) |
236 | |
287 | |
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288 | =item eio_truncate (const char *path, off_t offset, int pri, eio_cb cb, void *data) |
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289 | |
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290 | =item eio_chown (const char *path, uid_t uid, gid_t gid, int pri, eio_cb cb, void *data) |
|
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291 | |
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292 | =item eio_chmod (const char *path, mode_t mode, int pri, eio_cb cb, void *data) |
|
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293 | |
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294 | =item eio_mkdir (const char *path, mode_t mode, int pri, eio_cb cb, void *data) |
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295 | |
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296 | =item eio_rmdir (const char *path, int pri, eio_cb cb, void *data) |
|
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297 | |
|
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298 | =item eio_unlink (const char *path, int pri, eio_cb cb, void *data) |
|
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299 | |
237 | =item eio_utime (const char *path, eio_tstamp atime, eio_tstamp mtime, int pri, eio_cb cb, void *data) |
300 | =item eio_utime (const char *path, eio_tstamp atime, eio_tstamp mtime, int pri, eio_cb cb, void *data) |
238 | |
301 | |
239 | =item eio_truncate (const char *path, off_t offset, int pri, eio_cb cb, void *data) |
|
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240 | |
|
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241 | =item eio_chown (const char *path, uid_t uid, gid_t gid, int pri, eio_cb cb, void *data) |
|
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242 | |
|
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243 | =item eio_chmod (const char *path, mode_t mode, int pri, eio_cb cb, void *data) |
|
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244 | |
|
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245 | =item eio_mkdir (const char *path, mode_t mode, int pri, eio_cb cb, void *data) |
|
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246 | |
|
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247 | =item eio_rmdir (const char *path, int pri, eio_cb cb, void *data) |
|
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248 | |
|
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249 | =item eio_unlink (const char *path, int pri, eio_cb cb, void *data) |
|
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250 | |
|
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251 | =item eio_readlink (const char *path, int pri, eio_cb cb, void *data) /* result=ptr2 allocated dynamically */ |
|
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252 | |
|
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253 | =item eio_stat (const char *path, int pri, eio_cb cb, void *data) /* stat buffer=ptr2 allocated dynamically */ |
|
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254 | |
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255 | =item eio_lstat (const char *path, int pri, eio_cb cb, void *data) /* stat buffer=ptr2 allocated dynamically */ |
|
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256 | |
|
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257 | =item eio_statvfs (const char *path, int pri, eio_cb cb, void *data) /* stat buffer=ptr2 allocated dynamically */ |
|
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258 | |
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259 | =item eio_mknod (const char *path, mode_t mode, dev_t dev, int pri, eio_cb cb, void *data) |
302 | =item eio_mknod (const char *path, mode_t mode, dev_t dev, int pri, eio_cb cb, void *data) |
260 | |
303 | |
261 | =item eio_link (const char *path, const char *new_path, int pri, eio_cb cb, void *data) |
304 | =item eio_link (const char *path, const char *new_path, int pri, eio_cb cb, void *data) |
262 | |
305 | |
263 | =item eio_symlink (const char *path, const char *new_path, int pri, eio_cb cb, void *data) |
306 | =item eio_symlink (const char *path, const char *new_path, int pri, eio_cb cb, void *data) |
264 | |
307 | |
265 | =item eio_rename (const char *path, const char *new_path, int pri, eio_cb cb, void *data) |
308 | =item eio_rename (const char *path, const char *new_path, int pri, eio_cb cb, void *data) |
266 | |
309 | |
267 | =item eio_msync (void *addr, size_t length, int flags, int pri, eio_cb cb, void *data) |
|
|
268 | |
|
|
269 | =item eio_mlock (void *addr, size_t length, int pri, eio_cb cb, void *data) |
310 | =item eio_mlock (void *addr, size_t length, int pri, eio_cb cb, void *data) |
270 | |
|
|
271 | =item eio_mlockall (int flags, int pri, eio_cb cb, void *data) |
|
|
272 | |
311 | |
273 | =item eio_close (int fd, int pri, eio_cb cb, void *data) |
312 | =item eio_close (int fd, int pri, eio_cb cb, void *data) |
274 | |
313 | |
275 | =item eio_sync (int pri, eio_cb cb, void *data) |
314 | =item eio_sync (int pri, eio_cb cb, void *data) |
276 | |
315 | |
… | |
… | |
305 | |
344 | |
306 | Not surprisingly, pread and pwrite are not thread-safe on Darwin (OS/X), |
345 | Not surprisingly, pread and pwrite are not thread-safe on Darwin (OS/X), |
307 | so it is advised not to submit multiple requests on the same fd on this |
346 | so it is advised not to submit multiple requests on the same fd on this |
308 | horrible pile of garbage. |
347 | horrible pile of garbage. |
309 | |
348 | |
|
|
349 | =item eio_mlockall (int flags, int pri, eio_cb cb, void *data) |
|
|
350 | |
|
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351 | Like C<mlockall>, but the flag value constants are called |
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352 | C<EIO_MCL_CURRENT> and C<EIO_MCL_FUTURE>. |
|
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353 | |
|
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354 | =item eio_msync (void *addr, size_t length, int flags, int pri, eio_cb cb, void *data) |
|
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355 | |
|
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356 | Just like msync, except that the flag values are called C<EIO_MS_ASYNC>, |
|
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357 | C<EIO_MS_INVALIDATE> and C<EIO_MS_SYNC>. |
|
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358 | |
|
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359 | =item eio_readlink (const char *path, int pri, eio_cb cb, void *data) |
|
|
360 | |
|
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361 | If successful, the path read by C<readlink(2)> can be accessed via C<< |
|
|
362 | req->ptr2 >> and is I<NOT> null-terminated, with the length specified as |
|
|
363 | C<< req->result >>. |
|
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364 | |
|
|
365 | if (req->result >= 0) |
|
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366 | { |
|
|
367 | char *target = strndup ((char *)req->ptr2, req->result); |
|
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368 | |
|
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369 | free (target); |
|
|
370 | } |
|
|
371 | |
|
|
372 | =item eio_realpath (const char *path, int pri, eio_cb cb, void *data) |
|
|
373 | |
|
|
374 | Similar to the realpath libc function, but unlike that one, result is |
|
|
375 | C<-1> on failure and the length of the returned path in C<ptr2> (which is |
|
|
376 | not 0-terminated) - this is similar to readlink. |
|
|
377 | |
|
|
378 | =item eio_stat (const char *path, int pri, eio_cb cb, void *data) |
|
|
379 | |
|
|
380 | =item eio_lstat (const char *path, int pri, eio_cb cb, void *data) |
|
|
381 | |
310 | =item eio_fstat (int fd, int pri, eio_cb cb, void *data) |
382 | =item eio_fstat (int fd, int pri, eio_cb cb, void *data) |
311 | |
383 | |
312 | Stats a file - if C<< req->result >> indicates success, then you can |
384 | Stats a file - if C<< req->result >> indicates success, then you can |
313 | access the C<struct stat>-like structure via C<< req->ptr2 >>: |
385 | access the C<struct stat>-like structure via C<< req->ptr2 >>: |
314 | |
386 | |
315 | EIO_STRUCT_STAT *statdata = (EIO_STRUCT_STAT *)req->ptr2; |
387 | EIO_STRUCT_STAT *statdata = (EIO_STRUCT_STAT *)req->ptr2; |
316 | |
388 | |
317 | =item eio_fstatvfs (int fd, int pri, eio_cb cb, void *data) /* stat buffer=ptr2 allocated dynamically */ |
389 | =item eio_statvfs (const char *path, int pri, eio_cb cb, void *data) |
|
|
390 | |
|
|
391 | =item eio_fstatvfs (int fd, int pri, eio_cb cb, void *data) |
318 | |
392 | |
319 | Stats a filesystem - if C<< req->result >> indicates success, then you can |
393 | Stats a filesystem - if C<< req->result >> indicates success, then you can |
320 | access the C<struct statvfs>-like structure via C<< req->ptr2 >>: |
394 | access the C<struct statvfs>-like structure via C<< req->ptr2 >>: |
321 | |
395 | |
322 | EIO_STRUCT_STATVFS *statdata = (EIO_STRUCT_STATVFS *)req->ptr2; |
396 | EIO_STRUCT_STATVFS *statdata = (EIO_STRUCT_STATVFS *)req->ptr2; |
… | |
… | |
338 | (via the C<opendir>, C<readdir> and C<closedir> calls) and returns either |
412 | (via the C<opendir>, C<readdir> and C<closedir> calls) and returns either |
339 | the names or an array of C<struct eio_dirent>, depending on the C<flags> |
413 | the names or an array of C<struct eio_dirent>, depending on the C<flags> |
340 | argument. |
414 | argument. |
341 | |
415 | |
342 | The C<< req->result >> indicates either the number of files found, or |
416 | The C<< req->result >> indicates either the number of files found, or |
343 | C<-1> on error. On success, zero-terminated names can be found as C<< req->ptr2 >>, |
417 | C<-1> on error. On success, null-terminated names can be found as C<< req->ptr2 >>, |
344 | and C<struct eio_dirents>, if requested by C<flags>, can be found via C<< |
418 | and C<struct eio_dirents>, if requested by C<flags>, can be found via C<< |
345 | req->ptr1 >>. |
419 | req->ptr1 >>. |
346 | |
420 | |
347 | Here is an example that prints all the names: |
421 | Here is an example that prints all the names: |
348 | |
422 | |
… | |
… | |
480 | =item eio_sync_file_range (int fd, off_t offset, size_t nbytes, unsigned int flags, int pri, eio_cb cb, void *data) |
554 | =item eio_sync_file_range (int fd, off_t offset, size_t nbytes, unsigned int flags, int pri, eio_cb cb, void *data) |
481 | |
555 | |
482 | Calls C<sync_file_range>. If the syscall is missing, then this is the same |
556 | Calls C<sync_file_range>. If the syscall is missing, then this is the same |
483 | as calling C<fdatasync>. |
557 | as calling C<fdatasync>. |
484 | |
558 | |
|
|
559 | Flags can be any combination of C<EIO_SYNC_FILE_RANGE_WAIT_BEFORE>, |
|
|
560 | C<EIO_SYNC_FILE_RANGE_WRITE> and C<EIO_SYNC_FILE_RANGE_WAIT_AFTER>. |
|
|
561 | |
485 | =back |
562 | =back |
486 | |
563 | |
487 | =head3 LIBEIO-SPECIFIC REQUESTS |
564 | =head3 LIBEIO-SPECIFIC REQUESTS |
488 | |
565 | |
489 | These requests are specific to libeio and do not correspond to any OS call. |
566 | These requests are specific to libeio and do not correspond to any OS call. |
… | |
… | |
547 | |
624 | |
548 | =back |
625 | =back |
549 | |
626 | |
550 | =head3 GROUPING AND LIMITING REQUESTS |
627 | =head3 GROUPING AND LIMITING REQUESTS |
551 | |
628 | |
|
|
629 | There is one more rather special request, C<eio_grp>. It is a very special |
|
|
630 | aio request: Instead of doing something, it is a container for other eio |
|
|
631 | requests. |
|
|
632 | |
|
|
633 | There are two primary use cases for this: a) bundle many requests into a |
|
|
634 | single, composite, request with a definite callback and the ability to |
|
|
635 | cancel the whole request with its subrequests and b) limiting the number |
|
|
636 | of "active" requests. |
|
|
637 | |
|
|
638 | Further below you will find more dicussion of these topics - first follows |
|
|
639 | the reference section detailing the request generator and other methods. |
|
|
640 | |
|
|
641 | =over 4 |
|
|
642 | |
|
|
643 | =item eio_grp (eio_cb cb, void *data) |
|
|
644 | |
|
|
645 | Creates and submits a group request. |
|
|
646 | |
|
|
647 | =back |
|
|
648 | |
|
|
649 | |
|
|
650 | |
552 | #TODO |
651 | #TODO |
553 | |
652 | |
554 | /*****************************************************************************/ |
653 | /*****************************************************************************/ |
555 | /* groups */ |
654 | /* groups */ |
556 | |
655 | |