Annotation of embedaddon/libevent/evbuffer.c, revision 1.1.1.1

1.1       misho       1: /*
                      2:  * Copyright (c) 2002-2004 Niels Provos <provos@citi.umich.edu>
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms, with or without
                      6:  * modification, are permitted provided that the following conditions
                      7:  * are met:
                      8:  * 1. Redistributions of source code must retain the above copyright
                      9:  *    notice, this list of conditions and the following disclaimer.
                     10:  * 2. Redistributions in binary form must reproduce the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer in the
                     12:  *    documentation and/or other materials provided with the distribution.
                     13:  * 3. The name of the author may not be used to endorse or promote products
                     14:  *    derived from this software without specific prior written permission.
                     15:  *
                     16:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
                     17:  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
                     18:  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
                     19:  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
                     20:  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
                     21:  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
                     22:  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
                     23:  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
                     24:  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
                     25:  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
                     26:  */
                     27: 
                     28: #include <sys/types.h>
                     29: 
                     30: #ifdef HAVE_CONFIG_H
                     31: #include "config.h"
                     32: #endif
                     33: 
                     34: #ifdef HAVE_SYS_TIME_H
                     35: #include <sys/time.h>
                     36: #endif
                     37: 
                     38: #include <errno.h>
                     39: #include <stdio.h>
                     40: #include <stdlib.h>
                     41: #include <string.h>
                     42: #ifdef HAVE_STDARG_H
                     43: #include <stdarg.h>
                     44: #endif
                     45: 
                     46: #ifdef WIN32
                     47: #include <winsock2.h>
                     48: #endif
                     49: 
                     50: #include "evutil.h"
                     51: #include "event.h"
                     52: 
                     53: /* prototypes */
                     54: 
                     55: void bufferevent_read_pressure_cb(struct evbuffer *, size_t, size_t, void *);
                     56: 
                     57: static int
                     58: bufferevent_add(struct event *ev, int timeout)
                     59: {
                     60:        struct timeval tv, *ptv = NULL;
                     61: 
                     62:        if (timeout) {
                     63:                evutil_timerclear(&tv);
                     64:                tv.tv_sec = timeout;
                     65:                ptv = &tv;
                     66:        }
                     67: 
                     68:        return (event_add(ev, ptv));
                     69: }
                     70: 
                     71: /* 
                     72:  * This callback is executed when the size of the input buffer changes.
                     73:  * We use it to apply back pressure on the reading side.
                     74:  */
                     75: 
                     76: void
                     77: bufferevent_read_pressure_cb(struct evbuffer *buf, size_t old, size_t now,
                     78:     void *arg) {
                     79:        struct bufferevent *bufev = arg;
                     80:        /* 
                     81:         * If we are below the watermark then reschedule reading if it's
                     82:         * still enabled.
                     83:         */
                     84:        if (bufev->wm_read.high == 0 || now < bufev->wm_read.high) {
                     85:                evbuffer_setcb(buf, NULL, NULL);
                     86: 
                     87:                if (bufev->enabled & EV_READ)
                     88:                        bufferevent_add(&bufev->ev_read, bufev->timeout_read);
                     89:        }
                     90: }
                     91: 
                     92: static void
                     93: bufferevent_readcb(int fd, short event, void *arg)
                     94: {
                     95:        struct bufferevent *bufev = arg;
                     96:        int res = 0;
                     97:        short what = EVBUFFER_READ;
                     98:        size_t len;
                     99:        int howmuch = -1;
                    100: 
                    101:        if (event == EV_TIMEOUT) {
                    102:                what |= EVBUFFER_TIMEOUT;
                    103:                goto error;
                    104:        }
                    105: 
                    106:        /*
                    107:         * If we have a high watermark configured then we don't want to
                    108:         * read more data than would make us reach the watermark.
                    109:         */
                    110:        if (bufev->wm_read.high != 0) {
                    111:                howmuch = bufev->wm_read.high - EVBUFFER_LENGTH(bufev->input);
                    112:                /* we might have lowered the watermark, stop reading */
                    113:                if (howmuch <= 0) {
                    114:                        struct evbuffer *buf = bufev->input;
                    115:                        event_del(&bufev->ev_read);
                    116:                        evbuffer_setcb(buf,
                    117:                            bufferevent_read_pressure_cb, bufev);
                    118:                        return;
                    119:                }
                    120:        }
                    121: 
                    122:        res = evbuffer_read(bufev->input, fd, howmuch);
                    123:        if (res == -1) {
                    124:                if (errno == EAGAIN || errno == EINTR)
                    125:                        goto reschedule;
                    126:                /* error case */
                    127:                what |= EVBUFFER_ERROR;
                    128:        } else if (res == 0) {
                    129:                /* eof case */
                    130:                what |= EVBUFFER_EOF;
                    131:        }
                    132: 
                    133:        if (res <= 0)
                    134:                goto error;
                    135: 
                    136:        bufferevent_add(&bufev->ev_read, bufev->timeout_read);
                    137: 
                    138:        /* See if this callbacks meets the water marks */
                    139:        len = EVBUFFER_LENGTH(bufev->input);
                    140:        if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
                    141:                return;
                    142:        if (bufev->wm_read.high != 0 && len >= bufev->wm_read.high) {
                    143:                struct evbuffer *buf = bufev->input;
                    144:                event_del(&bufev->ev_read);
                    145: 
                    146:                /* Now schedule a callback for us when the buffer changes */
                    147:                evbuffer_setcb(buf, bufferevent_read_pressure_cb, bufev);
                    148:        }
                    149: 
                    150:        /* Invoke the user callback - must always be called last */
                    151:        if (bufev->readcb != NULL)
                    152:                (*bufev->readcb)(bufev, bufev->cbarg);
                    153:        return;
                    154: 
                    155:  reschedule:
                    156:        bufferevent_add(&bufev->ev_read, bufev->timeout_read);
                    157:        return;
                    158: 
                    159:  error:
                    160:        (*bufev->errorcb)(bufev, what, bufev->cbarg);
                    161: }
                    162: 
                    163: static void
                    164: bufferevent_writecb(int fd, short event, void *arg)
                    165: {
                    166:        struct bufferevent *bufev = arg;
                    167:        int res = 0;
                    168:        short what = EVBUFFER_WRITE;
                    169: 
                    170:        if (event == EV_TIMEOUT) {
                    171:                what |= EVBUFFER_TIMEOUT;
                    172:                goto error;
                    173:        }
                    174: 
                    175:        if (EVBUFFER_LENGTH(bufev->output)) {
                    176:            res = evbuffer_write(bufev->output, fd);
                    177:            if (res == -1) {
                    178: #ifndef WIN32
                    179: /*todo. evbuffer uses WriteFile when WIN32 is set. WIN32 system calls do not
                    180:  *set errno. thus this error checking is not portable*/
                    181:                    if (errno == EAGAIN ||
                    182:                        errno == EINTR ||
                    183:                        errno == EINPROGRESS)
                    184:                            goto reschedule;
                    185:                    /* error case */
                    186:                    what |= EVBUFFER_ERROR;
                    187: 
                    188: #else
                    189:                                goto reschedule;
                    190: #endif
                    191: 
                    192:            } else if (res == 0) {
                    193:                    /* eof case */
                    194:                    what |= EVBUFFER_EOF;
                    195:            }
                    196:            if (res <= 0)
                    197:                    goto error;
                    198:        }
                    199: 
                    200:        if (EVBUFFER_LENGTH(bufev->output) != 0)
                    201:                bufferevent_add(&bufev->ev_write, bufev->timeout_write);
                    202: 
                    203:        /*
                    204:         * Invoke the user callback if our buffer is drained or below the
                    205:         * low watermark.
                    206:         */
                    207:        if (bufev->writecb != NULL &&
                    208:            EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
                    209:                (*bufev->writecb)(bufev, bufev->cbarg);
                    210: 
                    211:        return;
                    212: 
                    213:  reschedule:
                    214:        if (EVBUFFER_LENGTH(bufev->output) != 0)
                    215:                bufferevent_add(&bufev->ev_write, bufev->timeout_write);
                    216:        return;
                    217: 
                    218:  error:
                    219:        (*bufev->errorcb)(bufev, what, bufev->cbarg);
                    220: }
                    221: 
                    222: /*
                    223:  * Create a new buffered event object.
                    224:  *
                    225:  * The read callback is invoked whenever we read new data.
                    226:  * The write callback is invoked whenever the output buffer is drained.
                    227:  * The error callback is invoked on a write/read error or on EOF.
                    228:  *
                    229:  * Both read and write callbacks maybe NULL.  The error callback is not
                    230:  * allowed to be NULL and have to be provided always.
                    231:  */
                    232: 
                    233: struct bufferevent *
                    234: bufferevent_new(int fd, evbuffercb readcb, evbuffercb writecb,
                    235:     everrorcb errorcb, void *cbarg)
                    236: {
                    237:        struct bufferevent *bufev;
                    238: 
                    239:        if ((bufev = calloc(1, sizeof(struct bufferevent))) == NULL)
                    240:                return (NULL);
                    241: 
                    242:        if ((bufev->input = evbuffer_new()) == NULL) {
                    243:                free(bufev);
                    244:                return (NULL);
                    245:        }
                    246: 
                    247:        if ((bufev->output = evbuffer_new()) == NULL) {
                    248:                evbuffer_free(bufev->input);
                    249:                free(bufev);
                    250:                return (NULL);
                    251:        }
                    252: 
                    253:        event_set(&bufev->ev_read, fd, EV_READ, bufferevent_readcb, bufev);
                    254:        event_set(&bufev->ev_write, fd, EV_WRITE, bufferevent_writecb, bufev);
                    255: 
                    256:        bufferevent_setcb(bufev, readcb, writecb, errorcb, cbarg);
                    257: 
                    258:        /*
                    259:         * Set to EV_WRITE so that using bufferevent_write is going to
                    260:         * trigger a callback.  Reading needs to be explicitly enabled
                    261:         * because otherwise no data will be available.
                    262:         */
                    263:        bufev->enabled = EV_WRITE;
                    264: 
                    265:        return (bufev);
                    266: }
                    267: 
                    268: void
                    269: bufferevent_setcb(struct bufferevent *bufev,
                    270:     evbuffercb readcb, evbuffercb writecb, everrorcb errorcb, void *cbarg)
                    271: {
                    272:        bufev->readcb = readcb;
                    273:        bufev->writecb = writecb;
                    274:        bufev->errorcb = errorcb;
                    275: 
                    276:        bufev->cbarg = cbarg;
                    277: }
                    278: 
                    279: void
                    280: bufferevent_setfd(struct bufferevent *bufev, int fd)
                    281: {
                    282:        event_del(&bufev->ev_read);
                    283:        event_del(&bufev->ev_write);
                    284: 
                    285:        event_set(&bufev->ev_read, fd, EV_READ, bufferevent_readcb, bufev);
                    286:        event_set(&bufev->ev_write, fd, EV_WRITE, bufferevent_writecb, bufev);
                    287:        if (bufev->ev_base != NULL) {
                    288:                event_base_set(bufev->ev_base, &bufev->ev_read);
                    289:                event_base_set(bufev->ev_base, &bufev->ev_write);
                    290:        }
                    291: 
                    292:        /* might have to manually trigger event registration */
                    293: }
                    294: 
                    295: int
                    296: bufferevent_priority_set(struct bufferevent *bufev, int priority)
                    297: {
                    298:        if (event_priority_set(&bufev->ev_read, priority) == -1)
                    299:                return (-1);
                    300:        if (event_priority_set(&bufev->ev_write, priority) == -1)
                    301:                return (-1);
                    302: 
                    303:        return (0);
                    304: }
                    305: 
                    306: /* Closing the file descriptor is the responsibility of the caller */
                    307: 
                    308: void
                    309: bufferevent_free(struct bufferevent *bufev)
                    310: {
                    311:        event_del(&bufev->ev_read);
                    312:        event_del(&bufev->ev_write);
                    313: 
                    314:        evbuffer_free(bufev->input);
                    315:        evbuffer_free(bufev->output);
                    316: 
                    317:        free(bufev);
                    318: }
                    319: 
                    320: /*
                    321:  * Returns 0 on success;
                    322:  *        -1 on failure.
                    323:  */
                    324: 
                    325: int
                    326: bufferevent_write(struct bufferevent *bufev, const void *data, size_t size)
                    327: {
                    328:        int res;
                    329: 
                    330:        res = evbuffer_add(bufev->output, data, size);
                    331: 
                    332:        if (res == -1)
                    333:                return (res);
                    334: 
                    335:        /* If everything is okay, we need to schedule a write */
                    336:        if (size > 0 && (bufev->enabled & EV_WRITE))
                    337:                bufferevent_add(&bufev->ev_write, bufev->timeout_write);
                    338: 
                    339:        return (res);
                    340: }
                    341: 
                    342: int
                    343: bufferevent_write_buffer(struct bufferevent *bufev, struct evbuffer *buf)
                    344: {
                    345:        int res;
                    346: 
                    347:        res = bufferevent_write(bufev, buf->buffer, buf->off);
                    348:        if (res != -1)
                    349:                evbuffer_drain(buf, buf->off);
                    350: 
                    351:        return (res);
                    352: }
                    353: 
                    354: size_t
                    355: bufferevent_read(struct bufferevent *bufev, void *data, size_t size)
                    356: {
                    357:        struct evbuffer *buf = bufev->input;
                    358: 
                    359:        if (buf->off < size)
                    360:                size = buf->off;
                    361: 
                    362:        /* Copy the available data to the user buffer */
                    363:        memcpy(data, buf->buffer, size);
                    364: 
                    365:        if (size)
                    366:                evbuffer_drain(buf, size);
                    367: 
                    368:        return (size);
                    369: }
                    370: 
                    371: int
                    372: bufferevent_enable(struct bufferevent *bufev, short event)
                    373: {
                    374:        if (event & EV_READ) {
                    375:                if (bufferevent_add(&bufev->ev_read, bufev->timeout_read) == -1)
                    376:                        return (-1);
                    377:        }
                    378:        if (event & EV_WRITE) {
                    379:                if (bufferevent_add(&bufev->ev_write, bufev->timeout_write) == -1)
                    380:                        return (-1);
                    381:        }
                    382: 
                    383:        bufev->enabled |= event;
                    384:        return (0);
                    385: }
                    386: 
                    387: int
                    388: bufferevent_disable(struct bufferevent *bufev, short event)
                    389: {
                    390:        if (event & EV_READ) {
                    391:                if (event_del(&bufev->ev_read) == -1)
                    392:                        return (-1);
                    393:        }
                    394:        if (event & EV_WRITE) {
                    395:                if (event_del(&bufev->ev_write) == -1)
                    396:                        return (-1);
                    397:        }
                    398: 
                    399:        bufev->enabled &= ~event;
                    400:        return (0);
                    401: }
                    402: 
                    403: /*
                    404:  * Sets the read and write timeout for a buffered event.
                    405:  */
                    406: 
                    407: void
                    408: bufferevent_settimeout(struct bufferevent *bufev,
                    409:     int timeout_read, int timeout_write) {
                    410:        bufev->timeout_read = timeout_read;
                    411:        bufev->timeout_write = timeout_write;
                    412: 
                    413:        if (event_pending(&bufev->ev_read, EV_READ, NULL))
                    414:                bufferevent_add(&bufev->ev_read, timeout_read);
                    415:        if (event_pending(&bufev->ev_write, EV_WRITE, NULL))
                    416:                bufferevent_add(&bufev->ev_write, timeout_write);
                    417: }
                    418: 
                    419: /*
                    420:  * Sets the water marks
                    421:  */
                    422: 
                    423: void
                    424: bufferevent_setwatermark(struct bufferevent *bufev, short events,
                    425:     size_t lowmark, size_t highmark)
                    426: {
                    427:        if (events & EV_READ) {
                    428:                bufev->wm_read.low = lowmark;
                    429:                bufev->wm_read.high = highmark;
                    430:        }
                    431: 
                    432:        if (events & EV_WRITE) {
                    433:                bufev->wm_write.low = lowmark;
                    434:                bufev->wm_write.high = highmark;
                    435:        }
                    436: 
                    437:        /* If the watermarks changed then see if we should call read again */
                    438:        bufferevent_read_pressure_cb(bufev->input,
                    439:            0, EVBUFFER_LENGTH(bufev->input), bufev);
                    440: }
                    441: 
                    442: int
                    443: bufferevent_base_set(struct event_base *base, struct bufferevent *bufev)
                    444: {
                    445:        int res;
                    446: 
                    447:        bufev->ev_base = base;
                    448: 
                    449:        res = event_base_set(base, &bufev->ev_read);
                    450:        if (res == -1)
                    451:                return (res);
                    452: 
                    453:        res = event_base_set(base, &bufev->ev_write);
                    454:        return (res);
                    455: }

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