libevent: fix race in the common case.

third_party/libevent/chromium.patch

 diff --git a/third_party/libevent/evdns.c b/third_party/libevent/evdns.c
 index f07ecc9..da6ea19 100644
 --- a/third_party/libevent/evdns.c
 +++ b/third_party/libevent/evdns.c
 @@ -134,7 +134,7 @@
  typedef ev_uint8_t u_char;
  typedef unsigned int uint;
  #endif
 -#include <event.h>
 +#include "event.h"
@@ skipping 63 matching lines @@
 +++ b/third_party/libevent/evutil.h
 @@ -38,7 +38,7 @@
  extern "C" {
  #endif
  
 -#include <event-config.h>
 +#include "event-config.h"
  #ifdef _EVENT_HAVE_SYS_TIME_H
  #include <sys/time.h>
  #endif
+diff --git a/third_party/libevent/event.c b/third_party/libevent/event.c
+index 1253352..598a98f 100644
+--- a/third_party/libevent/event.c
++++ b/third_party/libevent/event.c
+@@ -107,7 +107,7 @@ static const struct eventop *eventops[] = {
+ /* Global state */
+ struct event_base *current_base = NULL;
+ extern struct event_base *evsignal_base;
+-static int use_monotonic;
++static int no_monotonic_clock = 0;
+ 
+ /* Prototypes */
+ static void    event_queue_insert(struct event_base *, struct event *, int);
+@@ -120,17 +120,6 @@ static int timeout_next(struct event_base *, struct timeval **);
+ static void    timeout_process(struct event_base *);
+ static void    timeout_correct(struct event_base *, struct timeval *);
+ 
+-static void
+-detect_monotonic(void)
+-{
+-#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+-       struct timespec ts;
+-
+-       if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
+-               use_monotonic = 1;
+-#endif
+-}
+-
+ static int
+ gettime(struct event_base *base, struct timeval *tp)
+ {
+@@ -140,18 +129,18 @@ gettime(struct event_base *base, struct timeval *tp)
+        }
+ 
+ #if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+-       if (use_monotonic) {
+-               struct timespec ts;
+-
+-               if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
+-                       return (-1);
++       struct timespec ts;
+ 
++       if (no_monotonic_clock == 0 &&
++           clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
+                tp->tv_sec = ts.tv_sec;
+                tp->tv_usec = ts.tv_nsec / 1000;
+                return (0);
+        }
+ #endif
+ 
++       no_monotonic_clock = 1;
++
+        return (evutil_gettimeofday(tp, NULL));
+ }
+ 
+@@ -175,7 +164,6 @@ event_base_new(void)
+        if ((base = calloc(1, sizeof(struct event_base))) == NULL)
+                event_err(1, "%s: calloc", __func__);
+ 
+-       detect_monotonic();
+        gettime(base, &base->event_tv);
+        
+        min_heap_ctor(&base->timeheap);
+@@ -868,7 +856,7 @@ timeout_correct(struct event_base *base, struct timeval *tv)
+        unsigned int size;
+        struct timeval off;
+ 
+-       if (use_monotonic)
++       if (no_monotonic_clock == 0)
+                return;
+ 
+        /* Check if time is running backwards */