Annotation of embedaddon/libevent/evport.c, revision 1.1.1.1
1.1 misho 1: /*
2: * Submitted by David Pacheco (dp.spambait@gmail.com)
3: *
4: * Redistribution and use in source and binary forms, with or without
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: * 3. The name of the author may not be used to endorse or promote products
13: * derived from this software without specific prior written permission.
14: *
15: * THIS SOFTWARE IS PROVIDED BY SUN MICROSYSTEMS, INC. ``AS IS'' AND ANY
16: * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17: * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18: * DISCLAIMED. IN NO EVENT SHALL SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY
19: * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
20: * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
21: * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
22: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
24: * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
27: /*
28: * Copyright (c) 2007 Sun Microsystems. All rights reserved.
29: * Use is subject to license terms.
30: */
31:
32: /*
33: * evport.c: event backend using Solaris 10 event ports. See port_create(3C).
34: * This implementation is loosely modeled after the one used for select(2) (in
35: * select.c).
36: *
37: * The outstanding events are tracked in a data structure called evport_data.
38: * Each entry in the ed_fds array corresponds to a file descriptor, and contains
39: * pointers to the read and write events that correspond to that fd. (That is,
40: * when the file is readable, the "read" event should handle it, etc.)
41: *
42: * evport_add and evport_del update this data structure. evport_dispatch uses it
43: * to determine where to callback when an event occurs (which it gets from
44: * port_getn).
45: *
46: * Helper functions are used: grow() grows the file descriptor array as
47: * necessary when large fd's come in. reassociate() takes care of maintaining
48: * the proper file-descriptor/event-port associations.
49: *
50: * As in the select(2) implementation, signals are handled by evsignal.
51: */
52:
53: #ifdef HAVE_CONFIG_H
54: #include "config.h"
55: #endif
56:
57: #include <sys/time.h>
58: #include <assert.h>
59: #include <sys/queue.h>
60: #include <errno.h>
61: #include <poll.h>
62: #include <port.h>
63: #include <signal.h>
64: #include <stdio.h>
65: #include <stdlib.h>
66: #include <string.h>
67: #include <time.h>
68: #include <unistd.h>
69: #ifdef CHECK_INVARIANTS
70: #include <assert.h>
71: #endif
72:
73: #include "event.h"
74: #include "event-internal.h"
75: #include "log.h"
76: #include "evsignal.h"
77:
78:
79: /*
80: * Default value for ed_nevents, which is the maximum file descriptor number we
81: * can handle. If an event comes in for a file descriptor F > nevents, we will
82: * grow the array of file descriptors, doubling its size.
83: */
84: #define DEFAULT_NFDS 16
85:
86:
87: /*
88: * EVENTS_PER_GETN is the maximum number of events to retrieve from port_getn on
89: * any particular call. You can speed things up by increasing this, but it will
90: * (obviously) require more memory.
91: */
92: #define EVENTS_PER_GETN 8
93:
94: /*
95: * Per-file-descriptor information about what events we're subscribed to. These
96: * fields are NULL if no event is subscribed to either of them.
97: */
98:
99: struct fd_info {
100: struct event* fdi_revt; /* the event responsible for the "read" */
101: struct event* fdi_wevt; /* the event responsible for the "write" */
102: };
103:
104: #define FDI_HAS_READ(fdi) ((fdi)->fdi_revt != NULL)
105: #define FDI_HAS_WRITE(fdi) ((fdi)->fdi_wevt != NULL)
106: #define FDI_HAS_EVENTS(fdi) (FDI_HAS_READ(fdi) || FDI_HAS_WRITE(fdi))
107: #define FDI_TO_SYSEVENTS(fdi) (FDI_HAS_READ(fdi) ? POLLIN : 0) | \
108: (FDI_HAS_WRITE(fdi) ? POLLOUT : 0)
109:
110: struct evport_data {
111: int ed_port; /* event port for system events */
112: int ed_nevents; /* number of allocated fdi's */
113: struct fd_info *ed_fds; /* allocated fdi table */
114: /* fdi's that we need to reassoc */
115: int ed_pending[EVENTS_PER_GETN]; /* fd's with pending events */
116: };
117:
118: static void* evport_init (struct event_base *);
119: static int evport_add (void *, struct event *);
120: static int evport_del (void *, struct event *);
121: static int evport_dispatch (struct event_base *, void *, struct timeval *);
122: static void evport_dealloc (struct event_base *, void *);
123:
124: const struct eventop evportops = {
125: "evport",
126: evport_init,
127: evport_add,
128: evport_del,
129: evport_dispatch,
130: evport_dealloc,
131: 1 /* need reinit */
132: };
133:
134: /*
135: * Initialize the event port implementation.
136: */
137:
138: static void*
139: evport_init(struct event_base *base)
140: {
141: struct evport_data *evpd;
142: int i;
143: /*
144: * Disable event ports when this environment variable is set
145: */
146: if (evutil_getenv("EVENT_NOEVPORT"))
147: return (NULL);
148:
149: if (!(evpd = calloc(1, sizeof(struct evport_data))))
150: return (NULL);
151:
152: if ((evpd->ed_port = port_create()) == -1) {
153: free(evpd);
154: return (NULL);
155: }
156:
157: /*
158: * Initialize file descriptor structure
159: */
160: evpd->ed_fds = calloc(DEFAULT_NFDS, sizeof(struct fd_info));
161: if (evpd->ed_fds == NULL) {
162: close(evpd->ed_port);
163: free(evpd);
164: return (NULL);
165: }
166: evpd->ed_nevents = DEFAULT_NFDS;
167: for (i = 0; i < EVENTS_PER_GETN; i++)
168: evpd->ed_pending[i] = -1;
169:
170: evsignal_init(base);
171:
172: return (evpd);
173: }
174:
175: #ifdef CHECK_INVARIANTS
176: /*
177: * Checks some basic properties about the evport_data structure. Because it
178: * checks all file descriptors, this function can be expensive when the maximum
179: * file descriptor ever used is rather large.
180: */
181:
182: static void
183: check_evportop(struct evport_data *evpd)
184: {
185: assert(evpd);
186: assert(evpd->ed_nevents > 0);
187: assert(evpd->ed_port > 0);
188: assert(evpd->ed_fds > 0);
189:
190: /*
191: * Verify the integrity of the fd_info struct as well as the events to
192: * which it points (at least, that they're valid references and correct
193: * for their position in the structure).
194: */
195: int i;
196: for (i = 0; i < evpd->ed_nevents; ++i) {
197: struct event *ev;
198: struct fd_info *fdi;
199:
200: fdi = &evpd->ed_fds[i];
201: if ((ev = fdi->fdi_revt) != NULL) {
202: assert(ev->ev_fd == i);
203: }
204: if ((ev = fdi->fdi_wevt) != NULL) {
205: assert(ev->ev_fd == i);
206: }
207: }
208: }
209:
210: /*
211: * Verifies very basic integrity of a given port_event.
212: */
213: static void
214: check_event(port_event_t* pevt)
215: {
216: /*
217: * We've only registered for PORT_SOURCE_FD events. The only
218: * other thing we can legitimately receive is PORT_SOURCE_ALERT,
219: * but since we're not using port_alert either, we can assume
220: * PORT_SOURCE_FD.
221: */
222: assert(pevt->portev_source == PORT_SOURCE_FD);
223: assert(pevt->portev_user == NULL);
224: }
225:
226: #else
227: #define check_evportop(epop)
228: #define check_event(pevt)
229: #endif /* CHECK_INVARIANTS */
230:
231: /*
232: * Doubles the size of the allocated file descriptor array.
233: */
234: static int
235: grow(struct evport_data *epdp, int factor)
236: {
237: struct fd_info *tmp;
238: int oldsize = epdp->ed_nevents;
239: int newsize = factor * oldsize;
240: assert(factor > 1);
241:
242: check_evportop(epdp);
243:
244: tmp = realloc(epdp->ed_fds, sizeof(struct fd_info) * newsize);
245: if (NULL == tmp)
246: return -1;
247: epdp->ed_fds = tmp;
248: memset((char*) (epdp->ed_fds + oldsize), 0,
249: (newsize - oldsize)*sizeof(struct fd_info));
250: epdp->ed_nevents = newsize;
251:
252: check_evportop(epdp);
253:
254: return 0;
255: }
256:
257:
258: /*
259: * (Re)associates the given file descriptor with the event port. The OS events
260: * are specified (implicitly) from the fd_info struct.
261: */
262: static int
263: reassociate(struct evport_data *epdp, struct fd_info *fdip, int fd)
264: {
265: int sysevents = FDI_TO_SYSEVENTS(fdip);
266:
267: if (sysevents != 0) {
268: if (port_associate(epdp->ed_port, PORT_SOURCE_FD,
269: fd, sysevents, NULL) == -1) {
270: event_warn("port_associate");
271: return (-1);
272: }
273: }
274:
275: check_evportop(epdp);
276:
277: return (0);
278: }
279:
280: /*
281: * Main event loop - polls port_getn for some number of events, and processes
282: * them.
283: */
284:
285: static int
286: evport_dispatch(struct event_base *base, void *arg, struct timeval *tv)
287: {
288: int i, res;
289: struct evport_data *epdp = arg;
290: port_event_t pevtlist[EVENTS_PER_GETN];
291:
292: /*
293: * port_getn will block until it has at least nevents events. It will
294: * also return how many it's given us (which may be more than we asked
295: * for, as long as it's less than our maximum (EVENTS_PER_GETN)) in
296: * nevents.
297: */
298: int nevents = 1;
299:
300: /*
301: * We have to convert a struct timeval to a struct timespec
302: * (only difference is nanoseconds vs. microseconds). If no time-based
303: * events are active, we should wait for I/O (and tv == NULL).
304: */
305: struct timespec ts;
306: struct timespec *ts_p = NULL;
307: if (tv != NULL) {
308: ts.tv_sec = tv->tv_sec;
309: ts.tv_nsec = tv->tv_usec * 1000;
310: ts_p = &ts;
311: }
312:
313: /*
314: * Before doing anything else, we need to reassociate the events we hit
315: * last time which need reassociation. See comment at the end of the
316: * loop below.
317: */
318: for (i = 0; i < EVENTS_PER_GETN; ++i) {
319: struct fd_info *fdi = NULL;
320: if (epdp->ed_pending[i] != -1) {
321: fdi = &(epdp->ed_fds[epdp->ed_pending[i]]);
322: }
323:
324: if (fdi != NULL && FDI_HAS_EVENTS(fdi)) {
325: int fd = FDI_HAS_READ(fdi) ? fdi->fdi_revt->ev_fd :
326: fdi->fdi_wevt->ev_fd;
327: reassociate(epdp, fdi, fd);
328: epdp->ed_pending[i] = -1;
329: }
330: }
331:
332: if ((res = port_getn(epdp->ed_port, pevtlist, EVENTS_PER_GETN,
333: (unsigned int *) &nevents, ts_p)) == -1) {
334: if (errno == EINTR || errno == EAGAIN) {
335: evsignal_process(base);
336: return (0);
337: } else if (errno == ETIME) {
338: if (nevents == 0)
339: return (0);
340: } else {
341: event_warn("port_getn");
342: return (-1);
343: }
344: } else if (base->sig.evsignal_caught) {
345: evsignal_process(base);
346: }
347:
348: event_debug(("%s: port_getn reports %d events", __func__, nevents));
349:
350: for (i = 0; i < nevents; ++i) {
351: struct event *ev;
352: struct fd_info *fdi;
353: port_event_t *pevt = &pevtlist[i];
354: int fd = (int) pevt->portev_object;
355:
356: check_evportop(epdp);
357: check_event(pevt);
358: epdp->ed_pending[i] = fd;
359:
360: /*
361: * Figure out what kind of event it was
362: * (because we have to pass this to the callback)
363: */
364: res = 0;
365: if (pevt->portev_events & POLLIN)
366: res |= EV_READ;
367: if (pevt->portev_events & POLLOUT)
368: res |= EV_WRITE;
369:
370: assert(epdp->ed_nevents > fd);
371: fdi = &(epdp->ed_fds[fd]);
372:
373: /*
374: * We now check for each of the possible events (READ
375: * or WRITE). Then, we activate the event (which will
376: * cause its callback to be executed).
377: */
378:
379: if ((res & EV_READ) && ((ev = fdi->fdi_revt) != NULL)) {
380: event_active(ev, res, 1);
381: }
382:
383: if ((res & EV_WRITE) && ((ev = fdi->fdi_wevt) != NULL)) {
384: event_active(ev, res, 1);
385: }
386: } /* end of all events gotten */
387:
388: check_evportop(epdp);
389:
390: return (0);
391: }
392:
393:
394: /*
395: * Adds the given event (so that you will be notified when it happens via
396: * the callback function).
397: */
398:
399: static int
400: evport_add(void *arg, struct event *ev)
401: {
402: struct evport_data *evpd = arg;
403: struct fd_info *fdi;
404: int factor;
405:
406: check_evportop(evpd);
407:
408: /*
409: * Delegate, if it's not ours to handle.
410: */
411: if (ev->ev_events & EV_SIGNAL)
412: return (evsignal_add(ev));
413:
414: /*
415: * If necessary, grow the file descriptor info table
416: */
417:
418: factor = 1;
419: while (ev->ev_fd >= factor * evpd->ed_nevents)
420: factor *= 2;
421:
422: if (factor > 1) {
423: if (-1 == grow(evpd, factor)) {
424: return (-1);
425: }
426: }
427:
428: fdi = &evpd->ed_fds[ev->ev_fd];
429: if (ev->ev_events & EV_READ)
430: fdi->fdi_revt = ev;
431: if (ev->ev_events & EV_WRITE)
432: fdi->fdi_wevt = ev;
433:
434: return reassociate(evpd, fdi, ev->ev_fd);
435: }
436:
437: /*
438: * Removes the given event from the list of events to wait for.
439: */
440:
441: static int
442: evport_del(void *arg, struct event *ev)
443: {
444: struct evport_data *evpd = arg;
445: struct fd_info *fdi;
446: int i;
447: int associated = 1;
448:
449: check_evportop(evpd);
450:
451: /*
452: * Delegate, if it's not ours to handle
453: */
454: if (ev->ev_events & EV_SIGNAL) {
455: return (evsignal_del(ev));
456: }
457:
458: if (evpd->ed_nevents < ev->ev_fd) {
459: return (-1);
460: }
461:
462: for (i = 0; i < EVENTS_PER_GETN; ++i) {
463: if (evpd->ed_pending[i] == ev->ev_fd) {
464: associated = 0;
465: break;
466: }
467: }
468:
469: fdi = &evpd->ed_fds[ev->ev_fd];
470: if (ev->ev_events & EV_READ)
471: fdi->fdi_revt = NULL;
472: if (ev->ev_events & EV_WRITE)
473: fdi->fdi_wevt = NULL;
474:
475: if (associated) {
476: if (!FDI_HAS_EVENTS(fdi) &&
477: port_dissociate(evpd->ed_port, PORT_SOURCE_FD,
478: ev->ev_fd) == -1) {
479: /*
480: * Ignre EBADFD error the fd could have been closed
481: * before event_del() was called.
482: */
483: if (errno != EBADFD) {
484: event_warn("port_dissociate");
485: return (-1);
486: }
487: } else {
488: if (FDI_HAS_EVENTS(fdi)) {
489: return (reassociate(evpd, fdi, ev->ev_fd));
490: }
491: }
492: } else {
493: if (fdi->fdi_revt == NULL && fdi->fdi_wevt == NULL) {
494: evpd->ed_pending[i] = -1;
495: }
496: }
497: return 0;
498: }
499:
500:
501: static void
502: evport_dealloc(struct event_base *base, void *arg)
503: {
504: struct evport_data *evpd = arg;
505:
506: evsignal_dealloc(base);
507:
508: close(evpd->ed_port);
509:
510: if (evpd->ed_fds)
511: free(evpd->ed_fds);
512: free(evpd);
513: }
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