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/*
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* QEMU aio implementation
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*
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* Copyright IBM, Corp. 2008
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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* Contributions after 2012-01-13 are licensed under the terms of the
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* GNU GPL, version 2 or (at your option) any later version.
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*/
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#include "qemu-common.h" |
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#include "block/block.h" |
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#include "qemu/queue.h" |
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#include "qemu/sockets.h" |
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struct AioHandler
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{ |
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GPollFD pfd; |
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IOHandler *io_read; |
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IOHandler *io_write; |
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AioFlushHandler *io_flush; |
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int deleted;
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int pollfds_idx;
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void *opaque;
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QLIST_ENTRY(AioHandler) node; |
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}; |
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static AioHandler *find_aio_handler(AioContext *ctx, int fd) |
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{ |
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AioHandler *node; |
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QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
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if (node->pfd.fd == fd)
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if (!node->deleted)
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return node;
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} |
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return NULL; |
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} |
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void aio_set_fd_handler(AioContext *ctx,
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int fd,
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IOHandler *io_read, |
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IOHandler *io_write, |
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AioFlushHandler *io_flush, |
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void *opaque)
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{ |
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AioHandler *node; |
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node = find_aio_handler(ctx, fd); |
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/* Are we deleting the fd handler? */
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if (!io_read && !io_write) {
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if (node) {
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g_source_remove_poll(&ctx->source, &node->pfd); |
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/* If the lock is held, just mark the node as deleted */
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if (ctx->walking_handlers) {
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node->deleted = 1;
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node->pfd.revents = 0;
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} else {
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/* Otherwise, delete it for real. We can't just mark it as
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* deleted because deleted nodes are only cleaned up after
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* releasing the walking_handlers lock.
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*/
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QLIST_REMOVE(node, node); |
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g_free(node); |
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} |
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} |
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} else {
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if (node == NULL) { |
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/* Alloc and insert if it's not already there */
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node = g_malloc0(sizeof(AioHandler));
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node->pfd.fd = fd; |
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QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node); |
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g_source_add_poll(&ctx->source, &node->pfd); |
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} |
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/* Update handler with latest information */
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node->io_read = io_read; |
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node->io_write = io_write; |
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node->io_flush = io_flush; |
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node->opaque = opaque; |
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node->pollfds_idx = -1;
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node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0);
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node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0);
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} |
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aio_notify(ctx); |
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} |
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void aio_set_event_notifier(AioContext *ctx,
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EventNotifier *notifier, |
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EventNotifierHandler *io_read, |
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AioFlushEventNotifierHandler *io_flush) |
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{ |
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aio_set_fd_handler(ctx, event_notifier_get_fd(notifier), |
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(IOHandler *)io_read, NULL,
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(AioFlushHandler *)io_flush, notifier); |
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} |
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bool aio_pending(AioContext *ctx)
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{ |
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AioHandler *node; |
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QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
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int revents;
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revents = node->pfd.revents & node->pfd.events; |
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if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
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return true; |
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} |
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if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
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return true; |
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} |
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} |
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return false; |
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} |
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static bool aio_dispatch(AioContext *ctx) |
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{ |
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AioHandler *node; |
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bool progress = false; |
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/*
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* We have to walk very carefully in case qemu_aio_set_fd_handler is
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* called while we're walking.
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*/
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node = QLIST_FIRST(&ctx->aio_handlers); |
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while (node) {
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AioHandler *tmp; |
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int revents;
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ctx->walking_handlers++; |
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revents = node->pfd.revents & node->pfd.events; |
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node->pfd.revents = 0;
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if (!node->deleted &&
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(revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) && |
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node->io_read) { |
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node->io_read(node->opaque); |
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progress = true;
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} |
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if (!node->deleted &&
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(revents & (G_IO_OUT | G_IO_ERR)) && |
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node->io_write) { |
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node->io_write(node->opaque); |
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progress = true;
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} |
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tmp = node; |
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node = QLIST_NEXT(node, node); |
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ctx->walking_handlers--; |
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if (!ctx->walking_handlers && tmp->deleted) {
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QLIST_REMOVE(tmp, node); |
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g_free(tmp); |
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} |
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} |
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return progress;
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} |
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bool aio_poll(AioContext *ctx, bool blocking) |
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{ |
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AioHandler *node; |
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int ret;
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bool busy, progress;
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progress = false;
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/*
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* If there are callbacks left that have been queued, we need to call them.
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* Do not call select in this case, because it is possible that the caller
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* does not need a complete flush (as is the case for qemu_aio_wait loops).
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*/
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if (aio_bh_poll(ctx)) {
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blocking = false;
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progress = true;
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} |
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if (aio_dispatch(ctx)) {
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progress = true;
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} |
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if (progress && !blocking) {
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return true; |
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} |
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ctx->walking_handlers++; |
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g_array_set_size(ctx->pollfds, 0);
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/* fill pollfds */
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busy = false;
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QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
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node->pollfds_idx = -1;
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/* If there aren't pending AIO operations, don't invoke callbacks.
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* Otherwise, if there are no AIO requests, qemu_aio_wait() would
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* wait indefinitely.
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*/
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if (!node->deleted && node->io_flush) {
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if (node->io_flush(node->opaque) == 0) { |
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continue;
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} |
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busy = true;
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} |
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if (!node->deleted && node->pfd.events) {
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GPollFD pfd = { |
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.fd = node->pfd.fd, |
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.events = node->pfd.events, |
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}; |
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node->pollfds_idx = ctx->pollfds->len; |
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g_array_append_val(ctx->pollfds, pfd); |
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} |
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} |
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ctx->walking_handlers--; |
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/* No AIO operations? Get us out of here */
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if (!busy) {
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return progress;
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} |
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/* wait until next event */
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ret = g_poll((GPollFD *)ctx->pollfds->data, |
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ctx->pollfds->len, |
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blocking ? -1 : 0); |
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/* if we have any readable fds, dispatch event */
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if (ret > 0) { |
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QLIST_FOREACH(node, &ctx->aio_handlers, node) { |
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if (node->pollfds_idx != -1) { |
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GPollFD *pfd = &g_array_index(ctx->pollfds, GPollFD, |
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node->pollfds_idx); |
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node->pfd.revents = pfd->revents; |
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} |
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} |
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if (aio_dispatch(ctx)) {
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progress = true;
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} |
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} |
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assert(progress || busy); |
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return true; |
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} |