Add multithreading test for SamplingCircularQueue, fix implementation.

test/cctest/test-circular-queue.cc

Index: test/cctest/test-circular-queue.cc
diff --git a/test/cctest/test-circular-queue.cc b/test/cctest/test-circular-queue.cc
index bb69c1bc0245f059a455ce98617094c132115e74..3fa49bfaf3d2cdef923ee7d6a7fc07027fc34158 100644
--- a/test/cctest/test-circular-queue.cc
+++ b/test/cctest/test-circular-queue.cc
@@ -61,8 +61,6 @@ TEST(SamplingCircularQueue) {
   SamplingCircularQueue scq(sizeof(Record),
                             kRecordsPerChunk * sizeof(Record),
                             3);
-  scq.SetUpProducer();
-  scq.SetUpConsumer();
 
   // Check that we are using non-reserved values.
   CHECK_NE(SamplingCircularQueue::kClear, 1);
@@ -121,7 +119,103 @@ TEST(SamplingCircularQueue) {
   // Consumption must still be possible as the first cell of the
   // last chunk is not clean.
   CHECK_NE(NULL, scq.StartDequeue());
+}
+
+
+namespace {
+
+class ProducerThread: public i::Thread {
+ public:
+  typedef SamplingCircularQueue::Cell Record;
+
+  ProducerThread(SamplingCircularQueue* scq,
+                 int records_per_chunk,
+                 Record value,
+                 i::Semaphore* finished)
+      : scq_(scq),
+        records_per_chunk_(records_per_chunk),
+        value_(value),
+        finished_(finished) { }
+
+  virtual void Run() {
+    for (Record i = value_; i < value_ + records_per_chunk_; ++i) {
+      Record* rec = reinterpret_cast<Record*>(scq_->Enqueue());
+      CHECK_NE(NULL, rec);
+      *rec = i;
+    }
+
+    finished_->Signal();
+  }
+
+ private:
+  SamplingCircularQueue* scq_;
+  const int records_per_chunk_;
+  Record value_;
+  i::Semaphore* finished_;
+};
+
+}  // namespace
+
+TEST(SamplingCircularQueueMultithreading) {
+  // Emulate multiple VM threads working 'one thread at a time.'
+  // This test enqueues data from different threads. This corresponds
+  // to the case of profiling under Linux, where signal handler that
+  // does sampling is called in the context of different VM threads.
+
+  typedef ProducerThread::Record Record;
+  const int kRecordsPerChunk = 4;
+  SamplingCircularQueue scq(sizeof(Record),
+                            kRecordsPerChunk * sizeof(Record),
+                            3);
+  i::Semaphore* semaphore = i::OS::CreateSemaphore(0);
+  // Don't poll ahead, making possible to check data in the buffer
+  // immediately after enqueuing.
+  scq.FlushResidualRecords();
+
+  // Check that we are using non-reserved values.
+  CHECK_NE(SamplingCircularQueue::kClear, 1);
+  CHECK_NE(SamplingCircularQueue::kEnd, 1);
+  ProducerThread producer1(&scq, kRecordsPerChunk, 1, semaphore);
+  ProducerThread producer2(&scq, kRecordsPerChunk, 10, semaphore);
+  ProducerThread producer3(&scq, kRecordsPerChunk, 20, semaphore);
+
+  CHECK_EQ(NULL, scq.StartDequeue());
+  producer1.Start();
+  semaphore->Wait();
+  for (Record i = 1; i < 1 + kRecordsPerChunk; ++i) {
+    Record* rec = reinterpret_cast<Record*>(scq.StartDequeue());
+    CHECK_NE(NULL, rec);
+    CHECK_EQ(static_cast<int64_t>(i), static_cast<int64_t>(*rec));
+    CHECK_EQ(rec, reinterpret_cast<Record*>(scq.StartDequeue()));
+    scq.FinishDequeue();
+    CHECK_NE(rec, reinterpret_cast<Record*>(scq.StartDequeue()));
+  }
+
+  CHECK_EQ(NULL, scq.StartDequeue());
+  producer2.Start();
+  semaphore->Wait();
+  for (Record i = 10; i < 10 + kRecordsPerChunk; ++i) {
+    Record* rec = reinterpret_cast<Record*>(scq.StartDequeue());
+    CHECK_NE(NULL, rec);
+    CHECK_EQ(static_cast<int64_t>(i), static_cast<int64_t>(*rec));
+    CHECK_EQ(rec, reinterpret_cast<Record*>(scq.StartDequeue()));
+    scq.FinishDequeue();
+    CHECK_NE(rec, reinterpret_cast<Record*>(scq.StartDequeue()));
+  }
+
+  CHECK_EQ(NULL, scq.StartDequeue());
+  producer3.Start();
+  semaphore->Wait();
+  for (Record i = 20; i < 20 + kRecordsPerChunk; ++i) {
+    Record* rec = reinterpret_cast<Record*>(scq.StartDequeue());
+    CHECK_NE(NULL, rec);
+    CHECK_EQ(static_cast<int64_t>(i), static_cast<int64_t>(*rec));
+    CHECK_EQ(rec, reinterpret_cast<Record*>(scq.StartDequeue()));
+    scq.FinishDequeue();
+    CHECK_NE(rec, reinterpret_cast<Record*>(scq.StartDequeue()));
+  }
+
+  CHECK_EQ(NULL, scq.StartDequeue());
 
-  scq.TearDownConsumer();
-  scq.TearDownProducer();
+  delete semaphore;
 }