Added a wait with timeout to the platform semaphore class.

The code has been compiled and tested on Windows, Linux and Mac OS.

The FreeBSD version is a copy of the Linux version which should work on FreeBSD as well. According to the FreeBSD documentation clock_gettime is part of the standard C library so the assumption is that no additional link libraries is required for FreeBSD.
Review URL: http://codereview.chromium.org/48123

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1526 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

SConstruct

@@ -151,7 +151,7 @@ V8_EXTRA_FLAGS = {
 MKSNAPSHOT_EXTRA_FLAGS = {
   'gcc': {
     'os:linux': {
-      'LIBS': ['pthread'],
+      'LIBS': ['pthread', 'rt'],
     },
     'os:macos': {
       'LIBS': ['pthread'],
@@ -195,7 +195,7 @@ CCTEST_EXTRA_FLAGS = {
       'LIBPATH': [abspath('.')]
     },
     'os:linux': {
-      'LIBS':         ['pthread'],
+      'LIBS':         ['pthread', 'rt'],
     },
     'os:macos': {
       'LIBS':         ['pthread'],
@@ -233,7 +233,7 @@ SAMPLE_FLAGS = {
       'LIBPATH': ['.']
     },
     'os:linux': {
-      'LIBS':         ['pthread'],
+      'LIBS':         ['pthread', 'rt'],
     },
     'os:macos': {
       'LIBS':         ['pthread'],
@@ -301,7 +301,7 @@ D8_FLAGS = {
       'LIBS': ['readline']
     },
     'os:linux': {
-      'LIBS': ['pthread'],
+      'LIBS': ['pthread', 'rt'],
     },
     'os:macos': {
       'LIBS': ['pthread'],

src/platform-freebsd.cc

@@ -608,11 +608,13 @@ class FreeBSDSemaphore : public Semaphore {
   virtual ~FreeBSDSemaphore() { sem_destroy(&sem_); }
 
   virtual void Wait();
+  virtual bool Wait(int timeout);
   virtual void Signal() { sem_post(&sem_); }
  private:
   sem_t sem_;
 };
 
+
 void FreeBSDSemaphore::Wait() {
   while (true) {
     int result = sem_wait(&sem_);
@@ -621,6 +623,39 @@ void FreeBSDSemaphore::Wait() {
   }
 }
 
+
+bool FreeBSDSemaphore::Wait(int timeout) {
+  const long kOneSecondMicros = 1000000;  // NOLINT
+  const long kOneSecondNanos = 1000000000;  // NOLINT
+
+  // Split timeout into second and nanosecond parts.
+  long nanos = (timeout % kOneSecondMicros) * 1000;  // NOLINT
+  time_t secs = timeout / kOneSecondMicros;
+
+  // Get the current real time clock.
+  struct timespec ts;
+  if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
+    return false;
+  }
+
+  // Calculate realtime for end of timeout.
+  ts.tv_nsec += nanos;
+  if (ts.tv_nsec >= kOneSecondNanos) {
+    ts.tv_nsec -= kOneSecondNanos;
+    ts.tv_nsec++;
+  }
+  ts.tv_sec += secs;
+
+  // Wait for semaphore signalled or timeout.
+  while (true) {
+    int result = sem_timedwait(&sem_, &ts);
+    if (result == 0) return true;  // Successfully got semaphore.
+    if (result == -1 && errno == ETIMEDOUT) return false;  // Timeout.
+    CHECK(result == -1 && errno == EINTR);  // Signal caused spurious wakeup.
+  }
+}
+
+
 Semaphore* OS::CreateSemaphore(int count) {
   return new FreeBSDSemaphore(count);
 }

src/platform-linux.cc

@@ -592,11 +592,13 @@ class LinuxSemaphore : public Semaphore {
   virtual ~LinuxSemaphore() { sem_destroy(&sem_); }
 
   virtual void Wait();
+  virtual bool Wait(int timeout);
   virtual void Signal() { sem_post(&sem_); }
  private:
   sem_t sem_;
 };
 
+
 void LinuxSemaphore::Wait() {
   while (true) {
     int result = sem_wait(&sem_);
@@ -605,6 +607,39 @@ void LinuxSemaphore::Wait() {
   }
 }
 
+
+bool LinuxSemaphore::Wait(int timeout) {
+  const long kOneSecondMicros = 1000000;  // NOLINT
+  const long kOneSecondNanos = 1000000000;  // NOLINT
+
+  // Split timeout into second and nanosecond parts.
+  long nanos = (timeout % kOneSecondMicros) * 1000;  // NOLINT
+  time_t secs = timeout / kOneSecondMicros;
+
+  // Get the current realtime clock.
+  struct timespec ts;
+  if (clock_gettime(CLOCK_REALTIME, &ts) == -1) {
+    return false;
+  }
+
+  // Calculate real time for end of timeout.
+  ts.tv_nsec += nanos;
+  if (ts.tv_nsec >= kOneSecondNanos) {
+    ts.tv_nsec -= kOneSecondNanos;
+    ts.tv_nsec++;
+  }
+  ts.tv_sec += secs;
+
+  // Wait for semaphore signalled or timeout.
+  while (true) {
+    int result = sem_timedwait(&sem_, &ts);
+    if (result == 0) return true;  // Successfully got semaphore.
+    if (result == -1 && errno == ETIMEDOUT) return false;  // Timeout.
+    CHECK(result == -1 && errno == EINTR);  // Signal caused spurious wakeup.
+  }
+}
+
+
 Semaphore* OS::CreateSemaphore(int count) {
   return new LinuxSemaphore(count);
 }

src/platform-macos.cc

@@ -565,6 +565,8 @@ class MacOSSemaphore : public Semaphore {
   // platform is not needed here.
   void Wait() { semaphore_wait(semaphore_); }
 
+  bool Wait(int timeout);
+
   void Signal() { semaphore_signal(semaphore_); }
 
  private:
@@ -572,6 +574,14 @@ class MacOSSemaphore : public Semaphore {
 };
 
 
+bool MacOSSemaphore::Wait(int timeout) {
+  mach_timespec_t ts;
+  ts.tv_sec = timeout / 1000000;
+  ts.tv_nsec = (timeout % 1000000) * 1000;
+  return semaphore_timedwait(semaphore_, ts) != KERN_OPERATION_TIMED_OUT;
+}
+
+
 Semaphore* OS::CreateSemaphore(int count) {
   return new MacOSSemaphore(count);
 }

src/platform-win32.cc

@@ -1538,6 +1538,12 @@ class Win32Semaphore : public Semaphore {
     WaitForSingleObject(sem, INFINITE);
   }
 
+  bool Wait(int timeout) {
+    // Timeout in Windows API is in milliseconds.
+    DWORD millis_timeout = timeout / 1000;
+    return WaitForSingleObject(sem, millis_timeout) != WAIT_TIMEOUT;
+  }
+
   void Signal() {
     LONG dummy;
     ReleaseSemaphore(sem, 1, &dummy);

src/platform.h

@@ -410,10 +410,16 @@ class Semaphore {
  public:
   virtual ~Semaphore() {}
 
-  // Suspends the calling thread until the counter is non zero
+  // Suspends the calling thread until the semaphore counter is non zero
   // and then decrements the semaphore counter.
   virtual void Wait() = 0;
 
+  // Suspends the calling thread until the counter is non zero or the timeout
+  // time has passsed. If timeout happens the return value is false and the
+  // counter is unchanged. Otherwise the semaphore counter is decremented and
+  // true is returned. The timeout value is specified in microseconds.
+  virtual bool Wait(int timeout) = 0;
+
   // Increments the semaphore counter.
   virtual void Signal() = 0;
 };

test/cctest/test-lock.cc

@@ -38,3 +38,26 @@ TEST(ShallowLock) {
   CHECK_EQ(0, mutex->Unlock());
   delete mutex;
 }
+
+
+TEST(SemaphoreTimeout) {
+  bool ok;
+  Semaphore* sem = OS::CreateSemaphore(0);
+
+  // Semaphore not signalled - timeout.
+  ok = sem->Wait(0);
+  CHECK(!ok);
+  ok = sem->Wait(100);
+  CHECK(!ok);
+  ok = sem->Wait(1000);
+  CHECK(!ok);
+
+  // Semaphore signalled - no timeout.
+  sem->Signal();
+  ok = sem->Wait(0);
+  sem->Signal();
+  ok = sem->Wait(100);
+  sem->Signal();
+  ok = sem->Wait(1000);
+  CHECK(ok);
+}