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Import from old repository commit 61ef2b42a9c4ba8e1600f15bb0236765edc2ad45.

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Ben Pfaff
2009-07-08 13:19:16 -07:00
commit 064af42167
387 changed files with 75535 additions and 0 deletions
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lib/poll-loop.c Normal file
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/*
* Copyright (c) 2008, 2009 Nicira Networks.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <config.h>
#include "poll-loop.h"
#include <assert.h>
#include <errno.h>
#include <poll.h>
#include <stdlib.h>
#include <string.h>
#include "backtrace.h"
#include "coverage.h"
#include "dynamic-string.h"
#include "list.h"
#include "timeval.h"
#define THIS_MODULE VLM_poll_loop
#include "vlog.h"
/* An event that will wake the following call to poll_block(). */
struct poll_waiter {
/* Set when the waiter is created. */
struct list node; /* Element in global waiters list. */
int fd; /* File descriptor. */
short int events; /* Events to wait for (POLLIN, POLLOUT). */
poll_fd_func *function; /* Callback function, if any, or null. */
void *aux; /* Argument to callback function. */
struct backtrace *backtrace; /* Optionally, event that created waiter. */
/* Set only when poll_block() is called. */
struct pollfd *pollfd; /* Pointer to element of the pollfds array
(null if added from a callback). */
};
/* All active poll waiters. */
static struct list waiters = LIST_INITIALIZER(&waiters);
/* Number of elements in the waiters list. */
static size_t n_waiters;
/* Max time to wait in next call to poll_block(), in milliseconds, or -1 to
* wait forever. */
static int timeout = -1;
/* Backtrace of 'timeout''s registration, if debugging is enabled. */
static struct backtrace timeout_backtrace;
/* Callback currently running, to allow verifying that poll_cancel() is not
* being called on a running callback. */
#ifndef NDEBUG
static struct poll_waiter *running_cb;
#endif
static struct poll_waiter *new_waiter(int fd, short int events);
/* Registers 'fd' as waiting for the specified 'events' (which should be POLLIN
* or POLLOUT or POLLIN | POLLOUT). The following call to poll_block() will
* wake up when 'fd' becomes ready for one or more of the requested events.
*
* The event registration is one-shot: only the following call to poll_block()
* is affected. The event will need to be re-registered after poll_block() is
* called if it is to persist. */
struct poll_waiter *
poll_fd_wait(int fd, short int events)
{
COVERAGE_INC(poll_fd_wait);
return new_waiter(fd, events);
}
/* Causes the following call to poll_block() to block for no more than 'msec'
* milliseconds. If 'msec' is nonpositive, the following call to poll_block()
* will not block at all.
*
* The timer registration is one-shot: only the following call to poll_block()
* is affected. The timer will need to be re-registered after poll_block() is
* called if it is to persist. */
void
poll_timer_wait(int msec)
{
if (timeout < 0 || msec < timeout) {
timeout = MAX(0, msec);
if (VLOG_IS_DBG_ENABLED()) {
backtrace_capture(&timeout_backtrace);
}
}
}
/* Causes the following call to poll_block() to wake up immediately, without
* blocking. */
void
poll_immediate_wake(void)
{
poll_timer_wait(0);
}
static void PRINTF_FORMAT(2, 3)
log_wakeup(const struct backtrace *backtrace, const char *format, ...)
{
struct ds ds;
va_list args;
ds_init(&ds);
va_start(args, format);
ds_put_format_valist(&ds, format, args);
va_end(args);
if (backtrace) {
int i;
ds_put_char(&ds, ':');
for (i = 0; i < backtrace->n_frames; i++) {
ds_put_format(&ds, " 0x%x", backtrace->frames[i]);
}
}
VLOG_DBG("%s", ds_cstr(&ds));
ds_destroy(&ds);
}
/* Blocks until one or more of the events registered with poll_fd_wait()
* occurs, or until the minimum duration registered with poll_timer_wait()
* elapses, or not at all if poll_immediate_wake() has been called.
*
* Also executes any autonomous subroutines registered with poll_fd_callback(),
* if their file descriptors have become ready. */
void
poll_block(void)
{
static struct pollfd *pollfds;
static size_t max_pollfds;
struct poll_waiter *pw;
struct list *node;
int n_pollfds;
int retval;
assert(!running_cb);
if (max_pollfds < n_waiters) {
max_pollfds = n_waiters;
pollfds = xrealloc(pollfds, max_pollfds * sizeof *pollfds);
}
n_pollfds = 0;
LIST_FOR_EACH (pw, struct poll_waiter, node, &waiters) {
pw->pollfd = &pollfds[n_pollfds];
pollfds[n_pollfds].fd = pw->fd;
pollfds[n_pollfds].events = pw->events;
pollfds[n_pollfds].revents = 0;
n_pollfds++;
}
if (!timeout) {
COVERAGE_INC(poll_zero_timeout);
}
retval = time_poll(pollfds, n_pollfds, timeout);
if (retval < 0) {
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
VLOG_ERR_RL(&rl, "poll: %s", strerror(-retval));
} else if (!retval && VLOG_IS_DBG_ENABLED()) {
log_wakeup(&timeout_backtrace, "%d-ms timeout", timeout);
}
for (node = waiters.next; node != &waiters; ) {
pw = CONTAINER_OF(node, struct poll_waiter, node);
if (!pw->pollfd || !pw->pollfd->revents) {
if (pw->function) {
node = node->next;
continue;
}
} else {
if (VLOG_IS_DBG_ENABLED()) {
log_wakeup(pw->backtrace, "%s%s%s%s%s on fd %d",
pw->pollfd->revents & POLLIN ? "[POLLIN]" : "",
pw->pollfd->revents & POLLOUT ? "[POLLOUT]" : "",
pw->pollfd->revents & POLLERR ? "[POLLERR]" : "",
pw->pollfd->revents & POLLHUP ? "[POLLHUP]" : "",
pw->pollfd->revents & POLLNVAL ? "[POLLNVAL]" : "",
pw->fd);
}
if (pw->function) {
#ifndef NDEBUG
running_cb = pw;
#endif
pw->function(pw->fd, pw->pollfd->revents, pw->aux);
#ifndef NDEBUG
running_cb = NULL;
#endif
}
}
node = node->next;
poll_cancel(pw);
}
timeout = -1;
timeout_backtrace.n_frames = 0;
}
/* Registers 'function' to be called with argument 'aux' by poll_block() when
* 'fd' becomes ready for one of the events in 'events', which should be POLLIN
* or POLLOUT or POLLIN | POLLOUT.
*
* The callback registration persists until the event actually occurs. At that
* point, it is automatically de-registered. The callback function must
* re-register the event by calling poll_fd_callback() again within the
* callback, if it wants to be called back again later. */
struct poll_waiter *
poll_fd_callback(int fd, short int events, poll_fd_func *function, void *aux)
{
struct poll_waiter *pw = new_waiter(fd, events);
pw->function = function;
pw->aux = aux;
return pw;
}
/* Cancels the file descriptor event registered with poll_fd_wait() or
* poll_fd_callback(). 'pw' must be the struct poll_waiter returned by one of
* those functions.
*
* An event registered with poll_fd_wait() may be canceled from its time of
* registration until the next call to poll_block(). At that point, the event
* is automatically canceled by the system and its poll_waiter is freed.
*
* An event registered with poll_fd_callback() may be canceled from its time of
* registration until its callback is actually called. At that point, the
* event is automatically canceled by the system and its poll_waiter is
* freed. */
void
poll_cancel(struct poll_waiter *pw)
{
if (pw) {
assert(pw != running_cb);
list_remove(&pw->node);
free(pw->backtrace);
free(pw);
n_waiters--;
}
}
/* Creates and returns a new poll_waiter for 'fd' and 'events'. */
static struct poll_waiter *
new_waiter(int fd, short int events)
{
struct poll_waiter *waiter = xcalloc(1, sizeof *waiter);
assert(fd >= 0);
waiter->fd = fd;
waiter->events = events;
if (VLOG_IS_DBG_ENABLED()) {
waiter->backtrace = xmalloc(sizeof *waiter->backtrace);
backtrace_capture(waiter->backtrace);
}
list_push_back(&waiters, &waiter->node);
n_waiters++;
return waiter;
}