static void bev_async_consider_reading(struct bufferevent_async *beva) { size_t cur_size; size_t read_high; size_t at_most; int limit; struct bufferevent *bev = &beva->bev.bev; /* Don't read if there is a read in progress, or we do not * want to read. */ if (beva->read_in_progress || beva->bev.connecting) return; if (!beva->ok || !(bev->enabled&EV_READ)) { bev_async_del_read(beva); return; } /* Don't read if we're full */ cur_size = evbuffer_get_length(bev->input); read_high = bev->wm_read.high; if (read_high) { if (cur_size >= read_high) { bev_async_del_read(beva); return; } at_most = read_high - cur_size; } else { at_most = 16384; /* FIXME totally magic. */ } /* XXXX This over-commits. */ /* XXXX see also not above on cast on _bufferevent_get_write_max() */ limit = (int)_bufferevent_get_read_max(&beva->bev); if (at_most >= (size_t)limit && limit >= 0) at_most = limit; if (beva->bev.read_suspended) { bev_async_del_read(beva); return; } bufferevent_incref(bev); if (evbuffer_launch_read(bev->input, at_most, &beva->read_overlapped)) { beva->ok = 0; _bufferevent_run_eventcb(bev, BEV_EVENT_ERROR); bufferevent_decref(bev); } else { beva->read_in_progress = at_most; _bufferevent_decrement_read_buckets(&beva->bev, at_most); bev_async_add_read(beva); } return; }
static void bev_async_consider_reading(struct bufferevent_async *b) { size_t cur_size; size_t read_high; size_t at_most; int limit; /* Don't read if there is a read in progress, or we do not * want to read. */ if (!b->ok || b->read_in_progress || !(b->bev.bev.enabled&EV_READ)) return; /* Don't read if we're full */ cur_size = evbuffer_get_length(b->bev.bev.input); read_high = b->bev.bev.wm_read.high; if (read_high) { if (cur_size >= read_high) return; at_most = read_high - cur_size; } else { at_most = 16384; /* FIXME totally magic. */ } /* XXXX This over-commits. */ limit = _bufferevent_get_read_max(&b->bev); if (at_most >= limit) at_most = limit; if (b->bev.read_suspended) return; if (evbuffer_launch_read(b->bev.bev.input, at_most, &b->read_overlapped)) { EVUTIL_ASSERT(0); } else { b->read_in_progress = 1; } }
static void bufferevent_readcb(evutil_socket_t fd, short event, void *arg) { struct bufferevent *bufev = arg; struct bufferevent_private *bufev_p = EVUTIL_UPCAST(bufev, struct bufferevent_private, bev); struct evbuffer *input; int res = 0; short what = BEV_EVENT_READING; ev_ssize_t howmuch = -1, readmax=-1; _bufferevent_incref_and_lock(bufev); if (event == EV_TIMEOUT) { /* Note that we only check for event==EV_TIMEOUT. If * event==EV_TIMEOUT|EV_READ, we can safely ignore the * timeout, since a read has occurred */ what |= BEV_EVENT_TIMEOUT; goto error; } input = bufev->input; /* * If we have a high watermark configured then we don't want to * read more data than would make us reach the watermark. */ if (bufev->wm_read.high != 0) { howmuch = bufev->wm_read.high - evbuffer_get_length(input); /* 缓冲区超过高水位,挂起读。 */ if (howmuch <= 0) { bufferevent_wm_suspend_read(bufev); goto done; } } //因为用户可以限速,所以这么要检测最大的可读大小。 //如果没有限速的话,那么将返回16384字节,即16K //默认情况下是没有限速的。 readmax = _bufferevent_get_read_max(bufev_p); if (howmuch < 0 || howmuch > readmax) /* The use of -1 for "unlimited" * uglifies this code. XXXX */ howmuch = readmax; if (bufev_p->read_suspended) goto done; evbuffer_unfreeze(input, 0); res = evbuffer_read(input, fd, (int)howmuch); /* XXXX evbuffer_read would do better to take and return ev_ssize_t */ evbuffer_freeze(input, 0); if (res == -1) { int err = evutil_socket_geterror(fd); if (EVUTIL_ERR_RW_RETRIABLE(err)) //EINTER or EAGAIN goto reschedule; /* error case */ what |= BEV_EVENT_ERROR; } else if (res == 0) { /* eof case */ what |= BEV_EVENT_EOF; } if (res <= 0) goto error; _bufferevent_decrement_read_buckets(bufev_p, res); /* 数据大于低水平,调用用户设置的回调。 */ if (evbuffer_get_length(input) >= bufev->wm_read.low) _bufferevent_run_readcb(bufev); goto done; reschedule: goto done; error: bufferevent_disable(bufev, EV_READ); _bufferevent_run_eventcb(bufev, what); done: _bufferevent_decref_and_unlock(bufev); }
static void bufferevent_readcb(evutil_socket_t fd, short event, void *arg) { struct bufferevent *bufev = arg; struct bufferevent_private *bufev_p = EVUTIL_UPCAST(bufev, struct bufferevent_private, bev); struct evbuffer *input; int res = 0; short what = BEV_EVENT_READING; int howmuch = -1, readmax=-1; _bufferevent_incref_and_lock(bufev); if (event == EV_TIMEOUT) { what |= BEV_EVENT_TIMEOUT; goto error; } input = bufev->input; /* * If we have a high watermark configured then we don't want to * read more data than would make us reach the watermark. */ if (bufev->wm_read.high != 0) { howmuch = bufev->wm_read.high - evbuffer_get_length(input); /* we somehow lowered the watermark, stop reading */ if (howmuch <= 0) { bufferevent_wm_suspend_read(bufev); goto done; } } readmax = _bufferevent_get_read_max(bufev_p); if (howmuch < 0 || howmuch > readmax) /* The use of -1 for "unlimited" * uglifies this code. */ howmuch = readmax; if (bufev_p->read_suspended) goto done; evbuffer_unfreeze(input, 0); res = evbuffer_read(input, fd, howmuch); evbuffer_freeze(input, 0); if (res == -1) { int err = evutil_socket_geterror(fd); if (EVUTIL_ERR_RW_RETRIABLE(err)) goto reschedule; /* error case */ what |= BEV_EVENT_ERROR; } else if (res == 0) { /* eof case */ what |= BEV_EVENT_EOF; } if (res <= 0) goto error; _bufferevent_decrement_read_buckets(bufev_p, res); /* Invoke the user callback - must always be called last */ if (evbuffer_get_length(input) >= bufev->wm_read.low) _bufferevent_run_readcb(bufev); goto done; reschedule: goto done; error: bufferevent_disable(bufev, EV_READ); _bufferevent_run_eventcb(bufev, what); done: _bufferevent_decref_and_unlock(bufev); }