Use mutex/condition variables to synchronize threads

src/optimizing-compiler-thread.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_OPTIMIZING_COMPILER_THREAD_H_
 #define V8_OPTIMIZING_COMPILER_THREAD_H_
 
 #include "src/base/atomicops.h"
+#include "src/base/platform/condition-variable.h"
 #include "src/base/platform/mutex.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/time.h"
 #include "src/flags.h"
 #include "src/list.h"
 #include "src/unbound-queue-inl.h"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 12 matching lines @@
         stop_semaphore_(0),
         input_queue_semaphore_(0),
         input_queue_capacity_(FLAG_concurrent_recompilation_queue_length),
         input_queue_length_(0),
         input_queue_shift_(0),
         osr_buffer_capacity_(FLAG_concurrent_recompilation_queue_length + 4),
         osr_buffer_cursor_(0),
         osr_hits_(0),
         osr_attempts_(0),
         blocked_jobs_(0),
-        ref_count_(1),
+        ref_count_(0),
         tracing_enabled_(FLAG_trace_concurrent_recompilation),
         job_based_recompilation_(FLAG_job_based_recompilation),
         recompilation_delay_(FLAG_concurrent_recompilation_delay) {
     base::NoBarrier_Store(&stop_thread_,
                           static_cast<base::AtomicWord>(CONTINUE));
     input_queue_ = NewArray<OptimizedCompileJob*>(input_queue_capacity_);
     if (FLAG_concurrent_osr) {
       // Allocate and mark OSR buffer slots as empty.
       osr_buffer_ = NewArray<OptimizedCompileJob*>(osr_buffer_capacity_);
       for (int i = 0; i < osr_buffer_capacity_; i++) osr_buffer_[i] = NULL;
@@ skipping 37 matching lines @@
 
  private:
   class CompileTask;
 
   enum StopFlag { CONTINUE, STOP, FLUSH };
 
   void FlushInputQueue(bool restore_function_code);
   void FlushOutputQueue(bool restore_function_code);
   void FlushOsrBuffer(bool restore_function_code);
   void CompileNext(OptimizedCompileJob* job);
-  OptimizedCompileJob* NextInput(StopFlag* flag = NULL);
+  OptimizedCompileJob* NextInput(bool check_if_flushing = false);
 
   // Add a recompilation task for OSR to the cyclic buffer, awaiting OSR entry.
   // Tasks evicted from the cyclic buffer are discarded.
   void AddToOsrBuffer(OptimizedCompileJob* compiler);
 
   inline int InputQueueIndex(int i) {
     int result = (i + input_queue_shift_) % input_queue_capacity_;
     DCHECK_LE(0, result);
     DCHECK_LT(result, input_queue_capacity_);
     return result;
@@ skipping 28 matching lines @@
 
   volatile base::AtomicWord stop_thread_;
   base::TimeDelta time_spent_compiling_;
   base::TimeDelta time_spent_total_;
 
   int osr_hits_;
   int osr_attempts_;
 
   int blocked_jobs_;
 
-  volatile base::AtomicWord ref_count_;
+  int ref_count_;
+  base::Mutex ref_count_mutex_;
+  base::ConditionVariable ref_count_zero_;
 
   // Copies of FLAG_trace_concurrent_recompilation,
   // FLAG_concurrent_recompilation_delay and
   // FLAG_job_based_recompilation that will be used from the background thread.
   //
   // Since flags might get modified while the background thread is running, it
   // is not safe to access them directly.
   bool tracing_enabled_;
   bool job_based_recompilation_;
   int recompilation_delay_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OPTIMIZING_COMPILER_THREAD_H_