Add Semaphore and its test, and use it where semaphores are needed

util/synchronization/semaphore.cc

Index: util/synchronization/semaphore.cc
diff --git a/util/synchronization/semaphore.cc b/util/synchronization/semaphore.cc
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index 0000000000000000000000000000000000000000..d513fa0dd43981acc72b1ff155fa2d1e77616388
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+++ b/util/synchronization/semaphore.cc
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+// 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"
+#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_);
+}
+
+#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