Add Semaphore::TimedWait().

This also splits the per-OS Semaphore methods into their own files.

TEST=util_test Semaphore.*
R=rsesek@chromium.org, scottmg@chromium.org

Review URL: https://codereview.chromium.org/909263002

util/synchronization/semaphore.h

@@ -44,8 +44,21 @@ class Semaphore {
   //! Atomically decrements the value of the semaphore by 1. If the new value is
   //! negative, this function blocks and will not return until the semaphore’s
   //! value is incremented to 0 by Signal().
+  //!
+  //! \sa TimedWait()
   void Wait();
 
+  //! \brief Performs a timed wait (or “procure”) operation on the semaphore.
+  //!
+  //! \param[in] seconds The maximum number of seconds to wait for the operation
+  //!     to complete.
+  //!
+  //! \return `false` if the wait timed out, `true` otherwise.
+  //!
+  //! This method is simlar to Wait(), except that the amount of time that it
+  //! blocks is limited.
+  bool TimedWait(double seconds);
+
   //! \brief Performs the signal (or “post”) operation on the semaphore.
   //!
   //! Atomically increments the value of the semaphore by 1. If the new value is

util/synchronization/semaphore_mac.cc

@@ -0,0 +1,45 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/synchronization/semaphore.h"
+
+#include "base/logging.h"
+
+namespace crashpad {
+
+Semaphore::Semaphore(int value)
+    : semaphore_(dispatch_semaphore_create(value)) {
+  CHECK(semaphore_) << "dispatch_semaphore_create";
+}
+
+Semaphore::~Semaphore() {
+  dispatch_release(semaphore_);
+}
+
+void Semaphore::Wait() {
+  CHECK_EQ(dispatch_semaphore_wait(semaphore_, DISPATCH_TIME_FOREVER), 0);
+}
+
+bool Semaphore::TimedWait(double seconds) {
+  DCHECK_GE(seconds, 0.0);
+  const dispatch_time_t timeout =
+      dispatch_time(DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC);
+  return dispatch_semaphore_wait(semaphore_, timeout) == 0;
+}
+
+void Semaphore::Signal() {
+  dispatch_semaphore_signal(semaphore_);
+}
+
+}  // namespace crashpad

util/synchronization/semaphore_posix.cc

@@ -0,0 +1,57 @@
+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/synchronization/semaphore.h"
+
+#include <errno.h>
+
+#include <cmath>
+
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+
+namespace crashpad {
+
+#if !defined(OS_MACOSX)
+
+Semaphore::Semaphore(int value) {
+  PCHECK(sem_init(&semaphore_, 0, value) == 0) << "sem_init";
+}
+
+Semaphore::~Semaphore() {
+  PCHECK(sem_destroy(&semaphore_) == 0) << "sem_destroy";
+}
+
+void Semaphore::Wait() {
+  PCHECK(HANDLE_EINTR(sem_wait(&semaphore_)) == 0) << "sem_wait";
+}
+
+bool Semaphore::TimedWait(double seconds) {
+  DCHECK_GE(seconds, 0.0);
+  timespec timeout;
+  timeout.tv_sec = seconds;
+  timeout.tv_nsec = (seconds - trunc(seconds)) * 1E9;
+
+  int rv = HANDLE_EINTR(sem_timedwait(&semaphore_, &timeout));
+  PCHECK(rv == 0 || errno == ETIMEDOUT) << "sem_timedwait";
+  return rv == 0;
+}
+
+void Semaphore::Signal() {
+  PCHECK(sem_post(&semaphore_) == 0) << "sem_post";
+}
+
+#endif
+
+}  // namespace crashpad

util/synchronization/semaphore_test.cc

@@ -30,6 +30,17 @@ TEST(Semaphore, Simple) {
   semaphore.Signal();
 }
 
+TEST(Semaphore, TimedWait) {
+  Semaphore semaphore(0);
+  semaphore.Signal();
+  EXPECT_TRUE(semaphore.TimedWait(0.01));  // 10ms
+}
+
+TEST(Semaphore, TimedWaitTimeout) {
+  Semaphore semaphore(0);
+  EXPECT_FALSE(semaphore.TimedWait(0.01));  // 10ms
+}
+
 struct ThreadMainInfo {
 #if defined(OS_POSIX)
   pthread_t pthread;

util/synchronization/semaphore_win.cc

@@ -17,31 +17,9 @@
 #include <limits>
 
 #include "base/logging.h"
-#include "base/posix/eintr_wrapper.h"
 
 namespace crashpad {
 
-#if defined(OS_MACOSX)
-
-Semaphore::Semaphore(int value)
-    : semaphore_(dispatch_semaphore_create(value)) {
-  CHECK(semaphore_) << "dispatch_semaphore_create";
-}
-
-Semaphore::~Semaphore() {
-  dispatch_release(semaphore_);
-}
-
-void Semaphore::Wait() {
-  CHECK_EQ(dispatch_semaphore_wait(semaphore_, DISPATCH_TIME_FOREVER), 0);
-}
-
-void Semaphore::Signal() {
-  dispatch_semaphore_signal(semaphore_);
-}
-
-#elif defined(OS_WIN)
-
 Semaphore::Semaphore(int value)
     : semaphore_(CreateSemaphore(nullptr,
                                  value,
@@ -58,28 +36,15 @@ void Semaphore::Wait() {
   PCHECK(WaitForSingleObject(semaphore_, INFINITE) == WAIT_OBJECT_0);
 }
 
+bool Semaphore::TimedWait(double seconds) {
+  DCHECK_GE(seconds, 0.0);
+  DWORD rv = WaitForSingleObject(semaphore_, static_cast<DWORD>(seconds * 1E3));
+  PCHECK(rv == WAIT_OBJECT_0 || rv == WAIT_TIMEOUT) << "WaitForSingleObject";
+  return rv == WAIT_OBJECT_0;
+}
+
 void Semaphore::Signal() {
   PCHECK(ReleaseSemaphore(semaphore_, 1, nullptr));
 }
 
-#else
-
-Semaphore::Semaphore(int value) {
-  PCHECK(sem_init(&semaphore_, 0, value) == 0) << "sem_init";
-}
-
-Semaphore::~Semaphore() {
-  PCHECK(sem_destroy(&semaphore_)) << "sem_destroy";
-}
-
-void Semaphore::Wait() {
-  PCHECK(HANDLE_EINTR(sem_wait(&semaphore_))) << "sem_wait";
-}
-
-void Semaphore::Signal() {
-  PCHECK(sem_post(&semaphore_)) << "sem_post";
-}
-
-#endif
-
 }  // namespace crashpad

util/util.gyp

@@ -121,7 +121,9 @@
         'stdlib/strlcpy.h',
         'stdlib/strnlen.cc',
         'stdlib/strnlen.h',
-        'synchronization/semaphore.cc',
+        'synchronization/semaphore_mac.cc',
+        'synchronization/semaphore_posix.cc',
+        'synchronization/semaphore_win.cc',
         'synchronization/semaphore.h',
         'win/scoped_handle.cc',
         'win/scoped_handle.h',