[platform] Implement a worker pool

src/libplatform/default-platform.cc

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-#include "v8.h"
+#include "default-platform.h"
 
-#include "default-platform.h"
+#include <queue>
+
+// TODO(jochen): We should have our own version of checks.h.
+#include "../checks.h"
+// TODO(jochen): Why is cpu.h not in platform/?
+#include "../cpu.h"
+#include "worker-thread.h"
 
 namespace v8 {
 namespace internal {
 
 
-DefaultPlatform::DefaultPlatform() {}
+DefaultPlatform::DefaultPlatform()
+    : initialized_(false) {}
 
 
-DefaultPlatform::~DefaultPlatform() {}
+DefaultPlatform::~DefaultPlatform() {
+  LockGuard<Mutex> guard(&lock_);
+  if (initialized_) {
+    queue_.Terminate();
+    for (std::vector<WorkerThread*>::iterator i = thread_pool_.begin();
+         i != thread_pool_.end(); ++i) {
+      delete *i;
+    }
+  }
+}
+
+
+void DefaultPlatform::SetThreadPoolSize(int thread_pool_size) {
+  LockGuard<Mutex> guard(&lock_);
+  ASSERT(thread_pool_size >= 0);
+  if (initialized_) return;
+  initialized_ = true;
+  if (thread_pool_size < 1)
+    thread_pool_size = CPU::NumberOfProcessorsOnline();
+  thread_pool_size = Max(Min(thread_pool_size, kMaxThreadPoolSize), 1);
+
+  for (int i = 0; i < thread_pool_size; ++i)
+    thread_pool_.push_back(new WorkerThread(&queue_));
+}
 
 void DefaultPlatform::CallOnBackgroundThread(Task *task,
                                              ExpectedRuntime expected_runtime) {
-  // TODO(jochen): implement.
-  task->Run();
-  delete task;
+#ifdef DEBUG
+  {
+    LockGuard<Mutex> guard(&lock_);
+    ASSERT(initialized_);
+  }
+#endif
+  queue_.Append(task);
 }
 
 
 void DefaultPlatform::CallOnForegroundThread(v8::Isolate* isolate, Task* task) {
   // TODO(jochen): implement.
   task->Run();
   delete task;
 }
 
-
 } }  // namespace v8::internal