mirror of
https://github.com/openvswitch/ovs
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283 lines
8.8 KiB
C
283 lines
8.8 KiB
C
/*
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* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <config.h>
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#include "poll-loop.h"
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#include <errno.h>
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#include <inttypes.h>
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#include <poll.h>
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#include <stdlib.h>
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#include <string.h>
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#include "coverage.h"
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#include "dynamic-string.h"
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#include "fatal-signal.h"
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#include "list.h"
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#include "ovs-thread.h"
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#include "socket-util.h"
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#include "timeval.h"
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#include "vlog.h"
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VLOG_DEFINE_THIS_MODULE(poll_loop);
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COVERAGE_DEFINE(poll_fd_wait);
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COVERAGE_DEFINE(poll_zero_timeout);
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struct poll_loop {
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/* All active poll waiters. */
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struct pollfd *pollfds; /* Events to pass to poll(). */
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const char **where; /* Where each pollfd was created. */
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size_t n_waiters; /* Number of elems in 'where' and 'pollfds'. */
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size_t allocated_waiters; /* Allocated elems in 'where' and 'pollfds'. */
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/* Time at which to wake up the next call to poll_block(), LLONG_MIN to
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* wake up immediately, or LLONG_MAX to wait forever. */
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long long int timeout_when; /* In msecs as returned by time_msec(). */
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const char *timeout_where; /* Where 'timeout_when' was set. */
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};
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static struct poll_loop *poll_loop(void);
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/* Registers 'fd' as waiting for the specified 'events' (which should be POLLIN
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* or POLLOUT or POLLIN | POLLOUT). The following call to poll_block() will
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* wake up when 'fd' becomes ready for one or more of the requested events.
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*
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* The event registration is one-shot: only the following call to poll_block()
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* is affected. The event will need to be re-registered after poll_block() is
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* called if it is to persist.
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*
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* ('where' is used in debug logging. Commonly one would use poll_fd_wait() to
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* automatically provide the caller's source file and line number for
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* 'where'.) */
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void
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poll_fd_wait_at(int fd, short int events, const char *where)
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{
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struct poll_loop *loop = poll_loop();
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COVERAGE_INC(poll_fd_wait);
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if (loop->n_waiters >= loop->allocated_waiters) {
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loop->where = x2nrealloc(loop->where, &loop->allocated_waiters,
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sizeof *loop->where);
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loop->pollfds = xrealloc(loop->pollfds,
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(loop->allocated_waiters
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* sizeof *loop->pollfds));
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}
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loop->where[loop->n_waiters] = where;
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loop->pollfds[loop->n_waiters].fd = fd;
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loop->pollfds[loop->n_waiters].events = events;
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loop->n_waiters++;
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}
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/* Causes the following call to poll_block() to block for no more than 'msec'
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* milliseconds. If 'msec' is nonpositive, the following call to poll_block()
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* will not block at all.
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*
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* The timer registration is one-shot: only the following call to poll_block()
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* is affected. The timer will need to be re-registered after poll_block() is
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* called if it is to persist.
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*
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* ('where' is used in debug logging. Commonly one would use poll_timer_wait()
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* to automatically provide the caller's source file and line number for
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* 'where'.) */
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void
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poll_timer_wait_at(long long int msec, const char *where)
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{
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long long int now = time_msec();
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long long int when;
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if (msec <= 0) {
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/* Wake up immediately. */
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when = LLONG_MIN;
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} else if ((unsigned long long int) now + msec <= LLONG_MAX) {
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/* Normal case. */
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when = now + msec;
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} else {
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/* now + msec would overflow. */
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when = LLONG_MAX;
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}
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poll_timer_wait_until_at(when, where);
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}
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/* Causes the following call to poll_block() to wake up when the current time,
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* as returned by time_msec(), reaches 'when' or later. If 'when' is earlier
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* than the current time, the following call to poll_block() will not block at
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* all.
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*
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* The timer registration is one-shot: only the following call to poll_block()
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* is affected. The timer will need to be re-registered after poll_block() is
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* called if it is to persist.
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*
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* ('where' is used in debug logging. Commonly one would use
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* poll_timer_wait_until() to automatically provide the caller's source file
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* and line number for 'where'.) */
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void
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poll_timer_wait_until_at(long long int when, const char *where)
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{
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struct poll_loop *loop = poll_loop();
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if (when < loop->timeout_when) {
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loop->timeout_when = when;
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loop->timeout_where = where;
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}
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}
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/* Causes the following call to poll_block() to wake up immediately, without
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* blocking.
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*
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* ('where' is used in debug logging. Commonly one would use
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* poll_immediate_wake() to automatically provide the caller's source file and
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* line number for 'where'.) */
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void
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poll_immediate_wake_at(const char *where)
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{
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poll_timer_wait_at(0, where);
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}
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/* Logs, if appropriate, that the poll loop was awakened by an event
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* registered at 'where' (typically a source file and line number). The other
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* arguments have two possible interpretations:
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*
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* - If 'pollfd' is nonnull then it should be the "struct pollfd" that caused
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* the wakeup. 'timeout' is ignored.
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*
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* - If 'pollfd' is NULL then 'timeout' is the number of milliseconds after
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* which the poll loop woke up.
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*/
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static void
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log_wakeup(const char *where, const struct pollfd *pollfd, int timeout)
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{
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static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(10, 10);
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enum vlog_level level;
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int cpu_usage;
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struct ds s;
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cpu_usage = get_cpu_usage();
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if (VLOG_IS_DBG_ENABLED()) {
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level = VLL_DBG;
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} else if (cpu_usage > 50 && !VLOG_DROP_INFO(&rl)) {
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level = VLL_INFO;
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} else {
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return;
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}
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ds_init(&s);
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ds_put_cstr(&s, "wakeup due to ");
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if (pollfd) {
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char *description = describe_fd(pollfd->fd);
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if (pollfd->revents & POLLIN) {
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ds_put_cstr(&s, "[POLLIN]");
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}
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if (pollfd->revents & POLLOUT) {
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ds_put_cstr(&s, "[POLLOUT]");
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}
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if (pollfd->revents & POLLERR) {
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ds_put_cstr(&s, "[POLLERR]");
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}
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if (pollfd->revents & POLLHUP) {
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ds_put_cstr(&s, "[POLLHUP]");
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}
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if (pollfd->revents & POLLNVAL) {
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ds_put_cstr(&s, "[POLLNVAL]");
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}
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ds_put_format(&s, " on fd %d (%s)", pollfd->fd, description);
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free(description);
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} else {
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ds_put_format(&s, "%d-ms timeout", timeout);
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}
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if (where) {
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ds_put_format(&s, " at %s", where);
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}
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if (cpu_usage >= 0) {
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ds_put_format(&s, " (%d%% CPU usage)", cpu_usage);
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}
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VLOG(level, "%s", ds_cstr(&s));
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ds_destroy(&s);
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}
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/* Blocks until one or more of the events registered with poll_fd_wait()
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* occurs, or until the minimum duration registered with poll_timer_wait()
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* elapses, or not at all if poll_immediate_wake() has been called. */
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void
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poll_block(void)
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{
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struct poll_loop *loop = poll_loop();
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int elapsed;
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int retval;
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/* Register fatal signal events before actually doing any real work for
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* poll_block. */
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fatal_signal_wait();
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if (loop->timeout_when == LLONG_MIN) {
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COVERAGE_INC(poll_zero_timeout);
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}
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retval = time_poll(loop->pollfds, loop->n_waiters,
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loop->timeout_when, &elapsed);
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if (retval < 0) {
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static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
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VLOG_ERR_RL(&rl, "poll: %s", ovs_strerror(-retval));
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} else if (!retval) {
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log_wakeup(loop->timeout_where, NULL, elapsed);
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} else if (get_cpu_usage() > 50 || VLOG_IS_DBG_ENABLED()) {
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size_t i;
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for (i = 0; i < loop->n_waiters; i++) {
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if (loop->pollfds[i].revents) {
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log_wakeup(loop->where[i], &loop->pollfds[i], 0);
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}
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}
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}
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loop->timeout_when = LLONG_MAX;
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loop->timeout_where = NULL;
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loop->n_waiters = 0;
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/* Handle any pending signals before doing anything else. */
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fatal_signal_run();
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}
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static void
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free_poll_loop(void *loop_)
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{
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struct poll_loop *loop = loop_;
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free(loop->pollfds);
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free(loop->where);
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free(loop);
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}
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static struct poll_loop *
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poll_loop(void)
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{
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static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
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static pthread_key_t key;
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struct poll_loop *loop;
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if (ovsthread_once_start(&once)) {
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xpthread_key_create(&key, free_poll_loop);
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ovsthread_once_done(&once);
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}
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loop = pthread_getspecific(key);
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if (!loop) {
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loop = xzalloc(sizeof *loop);
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xpthread_setspecific(key, loop);
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}
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return loop;
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}
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