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

util/synchronization/semaphore_test.cc

Index: util/synchronization/semaphore_test.cc
diff --git a/util/synchronization/semaphore_test.cc b/util/synchronization/semaphore_test.cc
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index 0000000000000000000000000000000000000000..3eb53da7ac6318847451115743f61734d2f93a8e
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+++ b/util/synchronization/semaphore_test.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 <pthread.h>
+
+#include "gtest/gtest.h"
+
+namespace {
+
+using namespace crashpad;
+
+TEST(Semaphore, Simple) {
+  Semaphore semaphore(1);
+  semaphore.Wait();
+  semaphore.Signal();
+}
+
+struct ThreadMainInfo {
+  pthread_t pthread;
+  Semaphore* semaphore;
+  size_t iterations;
+};
+
+void* ThreadMain(void* argument) {
+  ThreadMainInfo* info = reinterpret_cast<ThreadMainInfo*>(argument);
+  for (size_t iteration = 0; iteration < info->iterations; ++iteration) {
+    info->semaphore->Wait();
+  }
+  return NULL;
+}
+
+TEST(Semaphore, Threaded) {
+  Semaphore semaphore(0);
+  ThreadMainInfo info;
+  info.semaphore = &semaphore;
+  info.iterations = 1;
+
+  int rv = pthread_create(&info.pthread, NULL, ThreadMain, &info);
+  ASSERT_EQ(0, rv) << "pthread_create";
+
+  semaphore.Signal();
+
+  rv = pthread_join(info.pthread, NULL);
+  ASSERT_EQ(0, rv) << "pthread_join";
+}
+
+TEST(Semaphore, TenThreaded) {
+  // This test has a smaller initial value (5) than threads contending for these
+  // resources (10), and the threads each try to obtain the resource a different
+  // number of times.
+  Semaphore semaphore(5);
+  const size_t kThreads = 10;
+  ThreadMainInfo info[kThreads];
+  size_t iterations = 0;
+  int rv;
+  for (size_t index = 0; index < kThreads; ++index) {
+    info[index].semaphore = &semaphore;
+    info[index].iterations = index;
+    iterations += info[index].iterations;
+
+    rv = pthread_create(&info[index].pthread, NULL, ThreadMain, &info[index]);
+    ASSERT_EQ(0, rv) << "pthread_create";
+  }
+
+  for (size_t iteration = 0; iteration < iterations; ++iteration) {
+    semaphore.Signal();
+  }
+
+  for (size_t index = 0; index < kThreads; ++index) {
+    rv = pthread_join(info[index].pthread, NULL);
+    ASSERT_EQ(0, rv) << "pthread_join";
+  }
+}
+
+}  // namespace