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https://github.com/cuberite/libevent.git
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Merge branch '21_choose_monotonic'
This commit is contained in:
Nick Mathewson
commit
5595a79ff1
@ -36,6 +36,10 @@ extern "C" {
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#include <time.h>
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#include <sys/queue.h>
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#ifdef EVENT__HAVE_MACH_MACH_TIME_H
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/* For mach_timebase_info */
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#include <mach/mach_time.h>
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#endif
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#include "event2/event_struct.h"
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#include "minheap-internal.h"
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#include "evsignal-internal.h"
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@ -64,6 +68,8 @@ extern "C" {
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#define HAVE_ANY_MONOTONIC 1
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#elif defined(EVENT__HAVE_MACH_ABSOLUTE_TIME)
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#define HAVE_ANY_MONOTONIC 1
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#elif defined(_WIN32)
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#define HAVE_ANY_MONOTONIC 1
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#endif
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/** Structure to define the backend of a given event_base. */
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@ -251,7 +257,21 @@ struct event_base {
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* too often. */
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struct timeval tv_cache;
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#if defined(EVENT__HAVE_MACH_ABSOLUTE_TIME)
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struct mach_timebase_info mach_timebase_units;
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#endif
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#if defined(EVENT__HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC) && defined(CLOCK_MONOTONIC_COARSE)
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#define CLOCK_IS_SELECTED
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int monotonic_clock;
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#endif
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#ifdef _WIN32
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DWORD last_tick_count;
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struct timeval adjust_tick_count;
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#endif
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#if defined(HAVE_ANY_MONOTONIC)
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/** True iff we should use our system's monotonic time implementation */
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/* TODO: Support systems where we don't need to detct monotonic time */
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int use_monotonic;
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/** Difference between internal time (maybe from clock_gettime) and
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* gettimeofday. */
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struct timeval tv_clock_diff;
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74
event.c
74
event.c
@ -46,9 +46,6 @@
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#ifdef EVENT__HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#ifdef EVENT__HAVE_MACH_MACH_TIME_H
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#include <mach/mach_time.h>
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#endif
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#include <ctype.h>
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#include <errno.h>
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#include <signal.h>
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@ -131,10 +128,6 @@ struct event_base *event_global_current_base_ = NULL;
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/* Global state */
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#ifdef HAVE_ANY_MONOTONIC
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static int use_monotonic;
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#endif
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static void *event_self_cbarg_ptr_ = NULL;
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/* Prototypes */
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@ -345,19 +338,11 @@ HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
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#define EVENT_BASE_ASSERT_LOCKED(base) \
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EVLOCK_ASSERT_LOCKED((base)->th_base_lock)
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#if defined(EVENT__HAVE_MACH_ABSOLUTE_TIME)
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struct mach_timebase_info mach_timebase_units;
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#endif
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/* The first time this function is called, it sets use_monotonic to 1
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* if we have a clock function that supports monotonic time */
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/* Set base->use_monotonic to 1 if we have a clock function that supports
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* monotonic time */
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static void
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detect_monotonic(void)
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detect_monotonic(struct event_base *base, const struct event_config *cfg)
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{
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static int use_monotonic_initialized = 0;
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if (use_monotonic_initialized)
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return;
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#if defined(EVENT__HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
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{
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/* CLOCK_MONOTONIC exists on FreeBSD, Linux, and Solaris.
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@ -365,25 +350,34 @@ detect_monotonic(void)
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* versions won't have it working. */
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struct timespec ts;
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if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
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use_monotonic = 1;
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if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
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base->use_monotonic = 1;
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#ifdef CLOCK_IS_SELECTED
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base->monotonic_clock = CLOCK_MONOTONIC;
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if (cfg == NULL ||
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!(cfg->flags & EVENT_BASE_FLAG_PRECISE_TIMER)) {
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if (clock_gettime(CLOCK_MONOTONIC_COARSE, &ts) == 0)
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base->monotonic_clock = CLOCK_MONOTONIC_COARSE;
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}
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#endif
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}
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}
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#elif defined(EVENT__HAVE_MACH_ABSOLUTE_TIME)
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{
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struct mach_timebase_info mi;
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/* OSX has mach_absolute_time() */
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if (mach_timebase_info(&mi) == 0 && mach_absolute_time() != 0) {
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use_monotonic = 1;
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base->use_monotonic = 1;
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/* mach_timebase_info tells us how to convert
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* mach_absolute_time() into nanoseconds, but we
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* want to use microseconds instead. */
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mi.denom *= 1000;
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memcpy(&mach_timebase_units, &mi, sizeof(mi));
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memcpy(&base->mach_timebase_units, &mi, sizeof(mi));
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}
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}
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#elif defined(_WIN32)
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base->use_monotonic = 1;
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#endif
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use_monotonic_initialized = 1;
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}
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/* How often (in seconds) do we check for changes in wall clock time relative
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@ -406,21 +400,43 @@ gettime(struct event_base *base, struct timeval *tp)
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}
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#ifdef HAVE_ANY_MONOTONIC
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if (use_monotonic) {
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if (base->use_monotonic) {
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#if defined(EVENT__HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
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struct timespec ts;
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#ifdef CLOCK_IS_SELECTED
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if (clock_gettime(base->monotonic_clock, &ts) == -1)
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return (-1);
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#else
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if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
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return (-1);
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#endif
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tp->tv_sec = ts.tv_sec;
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tp->tv_usec = ts.tv_nsec / 1000;
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#elif defined(EVENT__HAVE_MACH_ABSOLUTE_TIME)
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uint64_t abstime = mach_absolute_time();
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uint64_t usec;
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usec = (abstime * mach_timebase_units.numer)
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/ (mach_timebase_units.denom);
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usec = (abstime * base->mach_timebase_units.numer)
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/ (base->mach_timebase_units.denom);
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tp->tv_sec = usec / 1000000;
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tp->tv_usec = usec % 1000000;
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#elif defined(_WIN32)
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/* TODO: Support GetTickCount64. */
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/* TODO: Support alternate timer backends if the user asked
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* for a high-precision timer. QueryPerformanceCounter is
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* possibly a good idea, but it is also supposed to have
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* reliability issues under various circumstances. */
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DWORD ticks = GetTickCount();
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if (ticks < base->last_tick_count) {
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/* The 32-bit timer rolled over. Let's assume it only
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* happened once. Add 2**32 msec to adjust_tick_count. */
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const struct timeval tv_rollover = { 4294967, 296000 };
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evutil_timeradd(&tv_rollover, &base->adjust_tick_count, &base->adjust_tick_count);
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}
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base->last_tick_count = ticks;
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tp->tv_sec = ticks / 1000;
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tp->tv_usec = (ticks % 1000) * 1000;
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evutil_timeradd(tp, &base->adjust_tick_count, tp);
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#else
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#error "Missing monotonic time implementation."
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#endif
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@ -631,7 +647,7 @@ event_base_new_with_config(const struct event_config *cfg)
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event_warn("%s: calloc", __func__);
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return NULL;
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}
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detect_monotonic();
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detect_monotonic(base, cfg);
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gettime(base, &base->event_tv);
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min_heap_ctor_(&base->timeheap);
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@ -2621,7 +2637,7 @@ timeout_correct(struct event_base *base, struct timeval *tv)
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int i;
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#ifdef HAVE_ANY_MONOTONIC
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if (use_monotonic)
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if (base->use_monotonic)
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return;
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#endif
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@ -481,7 +481,14 @@ enum event_base_config_flag {
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This flag has no effect if you wind up using a backend other than
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epoll.
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*/
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EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST = 0x10
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EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST = 0x10,
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/** Ordinarily, Libevent implements its time and timeout code using
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the fastest monotonic timer that we have. If this flag is set,
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however, we use less efficient more precise timer, assuming one is
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present.
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*/
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EVENT_BASE_FLAG_PRECISE_TIMER = 0x20
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};
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/**
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