Fix race conditions in cctest/test-debug.

test/cctest/test-debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 20 matching lines @@
 
 #define V8_DISABLE_DEPRECATIONS 1
 #include "v8.h"
 
 #include "api.h"
 #include "cctest.h"
 #include "compilation-cache.h"
 #include "debug.h"
 #include "deoptimizer.h"
 #include "platform.h"
+#include "platform/condition-variable.h"
 #include "stub-cache.h"
 #include "utils.h"
 #undef V8_DISABLE_DEPRECATIONS
 
 
+using ::v8::internal::Mutex;
+using ::v8::internal::LockGuard;
+using ::v8::internal::ConditionVariable;
+using ::v8::internal::Semaphore;
 using ::v8::internal::EmbeddedVector;
 using ::v8::internal::Object;
 using ::v8::internal::OS;
 using ::v8::internal::Handle;
 using ::v8::internal::Heap;
 using ::v8::internal::JSGlobalProxy;
 using ::v8::internal::Code;
 using ::v8::internal::Debug;
 using ::v8::internal::Debugger;
 using ::v8::internal::CommandMessage;
@@ skipping 4604 matching lines @@
       "obj_mirror.property('a').value().value() == 1")->BooleanValue());
   CHECK(CompileRun(
       "obj_mirror.property('b').value().value() == 2")->BooleanValue());
 }
 
 
 // Multithreaded tests of JSON debugger protocol
 
 // Support classes
 
-// Provides synchronization between k threads, where k is an input to the
-// constructor.  The Wait() call blocks a thread until it is called for the
-// k'th time, then all calls return.  Each ThreadBarrier object can only
-// be used once.
-class ThreadBarrier {
+// Provides synchronization between N threads, where N is a template parameter.
+// The Wait() call blocks a thread until it is called for the Nth time, then all
+// calls return.  Each ThreadBarrier object can only be used once.
+template <int N>
+class ThreadBarrier V8_FINAL {
  public:
-  explicit ThreadBarrier(int num_threads);
-  ~ThreadBarrier();
-  void Wait();
+  ThreadBarrier() : num_blocked_(0) {}
+
+  ~ThreadBarrier() {
+    LockGuard<Mutex> lock_guard(&mutex_);
+    if (num_blocked_ != 0) {
+      CHECK_EQ(N, num_blocked_);
+    }
+  }
+
+  void Wait() {
+    LockGuard<Mutex> lock_guard(&mutex_);
+    CHECK_LT(num_blocked_, N);
+    num_blocked_++;
+    if (N == num_blocked_) {
+      // Signal and unblock all waiting threads.
+      cv_.NotifyAll();
+      printf("BARRIER\n\n");
+      fflush(stdout);
+    } else {  // Wait for the semaphore.
+      while (num_blocked_ < N) {
+        cv_.Wait(&mutex_);
+      }
+    }
+    CHECK_EQ(N, num_blocked_);
+  }
+
  private:
-  int num_threads_;
+  ConditionVariable cv_;
+  Mutex mutex_;
   int num_blocked_;
-  v8::internal::Mutex lock_;
-  v8::internal::Semaphore sem_;
-  bool invalid_;
+
+  STATIC_CHECK(N > 0);
+
+  DISALLOW_COPY_AND_ASSIGN(ThreadBarrier);
 };
 
-ThreadBarrier::ThreadBarrier(int num_threads)
-    : num_threads_(num_threads), num_blocked_(0), sem_(0) {
-  invalid_ = false;  // A barrier may only be used once.  Then it is invalid.
-}
-
-
-// Do not call, due to race condition with Wait().
-// Could be resolved with Pthread condition variables.
-ThreadBarrier::~ThreadBarrier() {
-}
-
-
-void ThreadBarrier::Wait() {
-  lock_.Lock();
-  CHECK(!invalid_);
-  if (num_blocked_ == num_threads_ - 1) {
-    // Signal and unblock all waiting threads.
-    for (int i = 0; i < num_threads_ - 1; ++i) {
-      sem_.Signal();
-    }
-    invalid_ = true;
-    printf("BARRIER\n\n");
-    fflush(stdout);
-    lock_.Unlock();
-  } else {  // Wait for the semaphore.
-    ++num_blocked_;
-    lock_.Unlock();  // Potential race condition with destructor because
-    sem_.Wait();  // these two lines are not atomic.
-  }
-}
-
 
 // A set containing enough barriers and semaphores for any of the tests.
 class Barriers {
  public:
-  Barriers();
-  void Initialize();
-  ThreadBarrier barrier_1;
-  ThreadBarrier barrier_2;
-  ThreadBarrier barrier_3;
-  ThreadBarrier barrier_4;
-  ThreadBarrier barrier_5;
-  v8::internal::Semaphore* semaphore_1;
-  v8::internal::Semaphore* semaphore_2;
+  Barriers() : semaphore_1(0), semaphore_2(0) {}
+  ThreadBarrier<2> barrier_1;
+  ThreadBarrier<2> barrier_2;
+  ThreadBarrier<2> barrier_3;
+  ThreadBarrier<2> barrier_4;
+  ThreadBarrier<2> barrier_5;
+  v8::internal::Semaphore semaphore_1;
+  v8::internal::Semaphore semaphore_2;
 };
 
-Barriers::Barriers() : barrier_1(2), barrier_2(2),
-    barrier_3(2), barrier_4(2), barrier_5(2) {}
-
-void Barriers::Initialize() {
-  semaphore_1 = new v8::internal::Semaphore(0);
-  semaphore_2 = new v8::internal::Semaphore(0);
-}
-
 
 // We match parts of the message to decide if it is a break message.
 bool IsBreakEventMessage(char *message) {
   const char* type_event = "\"type\":\"event\"";
   const char* event_break = "\"event\":\"break\"";
   // Does the message contain both type:event and event:break?
   return strstr(message, type_event) != NULL &&
          strstr(message, event_break) != NULL;
 }
 
@@ skipping 91 matching lines @@
   void Run();
 };
 
 
 static void MessageHandler(const v8::Debug::Message& message) {
   v8::Handle<v8::String> json = message.GetJSON();
   v8::String::AsciiValue ascii(json);
   if (IsBreakEventMessage(*ascii)) {
     // Lets test script wait until break occurs to send commands.
     // Signals when a break is reported.
-    message_queue_barriers.semaphore_2->Signal();
+    message_queue_barriers.semaphore_2.Signal();
   }
 
   // Allow message handler to block on a semaphore, to test queueing of
   // messages while blocked.
-  message_queue_barriers.semaphore_1->Wait();
+  message_queue_barriers.semaphore_1.Wait();
 }
 
 
 void MessageQueueDebuggerThread::Run() {
   const int kBufferSize = 1000;
   uint16_t buffer_1[kBufferSize];
   uint16_t buffer_2[kBufferSize];
   const char* command_1 =
       "{\"seq\":117,"
        "\"type\":\"request\","
@@ skipping 14 matching lines @@
      "\"type\":\"request\","
      "\"command\":\"continue\"}";
   const char* command_single_step =
     "{\"seq\":107,"
      "\"type\":\"request\","
      "\"command\":\"continue\","
      "\"arguments\":{\"stepaction\":\"next\"}}";
 
   /* Interleaved sequence of actions by the two threads:*/
   // Main thread compiles and runs source_1
-  message_queue_barriers.semaphore_1->Signal();
+  message_queue_barriers.semaphore_1.Signal();
   message_queue_barriers.barrier_1.Wait();
   // Post 6 commands, filling the command queue and making it expand.
   // These calls return immediately, but the commands stay on the queue
   // until the execution of source_2.
   // Note: AsciiToUtf16 executes before SendCommand, so command is copied
   // to buffer before buffer is sent to SendCommand.
   v8::Debug::SendCommand(buffer_1, AsciiToUtf16(command_1, buffer_1));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_2, buffer_2));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_3, buffer_2));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_3, buffer_2));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_3, buffer_2));
   message_queue_barriers.barrier_2.Wait();
   // Main thread compiles and runs source_2.
   // Queued commands are executed at the start of compilation of source_2(
   // beforeCompile event).
   // Free the message handler to process all the messages from the queue. 7
   // messages are expected: 2 afterCompile events and 5 responses.
   // All the commands added so far will fail to execute as long as call stack
   // is empty on beforeCompile event.
   for (int i = 0; i < 6 ; ++i) {
-    message_queue_barriers.semaphore_1->Signal();
+    message_queue_barriers.semaphore_1.Signal();
   }
   message_queue_barriers.barrier_3.Wait();
   // Main thread compiles and runs source_3.
   // Don't stop in the afterCompile handler.
-  message_queue_barriers.semaphore_1->Signal();
+  message_queue_barriers.semaphore_1.Signal();
   // source_3 includes a debugger statement, which causes a break event.
   // Wait on break event from hitting "debugger" statement
-  message_queue_barriers.semaphore_2->Wait();
+  message_queue_barriers.semaphore_2.Wait();
   // These should execute after the "debugger" statement in source_2
   v8::Debug::SendCommand(buffer_1, AsciiToUtf16(command_1, buffer_1));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_2, buffer_2));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_3, buffer_2));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_single_step, buffer_2));
   // Run after 2 break events, 4 responses.
   for (int i = 0; i < 6 ; ++i) {
-    message_queue_barriers.semaphore_1->Signal();
+    message_queue_barriers.semaphore_1.Signal();
   }
   // Wait on break event after a single step executes.
-  message_queue_barriers.semaphore_2->Wait();
+  message_queue_barriers.semaphore_2.Wait();
   v8::Debug::SendCommand(buffer_1, AsciiToUtf16(command_2, buffer_1));
   v8::Debug::SendCommand(buffer_2, AsciiToUtf16(command_continue, buffer_2));
   // Run after 2 responses.
   for (int i = 0; i < 2 ; ++i) {
-    message_queue_barriers.semaphore_1->Signal();
+    message_queue_barriers.semaphore_1.Signal();
   }
   // Main thread continues running source_3 to end, waits for this thread.
 }
 
 
 // This thread runs the v8 engine.
 TEST(MessageQueues) {
   MessageQueueDebuggerThread message_queue_debugger_thread;
 
   // Create a V8 environment
   DebugLocalContext env;
   v8::HandleScope scope(env->GetIsolate());
-  message_queue_barriers.Initialize();
   v8::Debug::SetMessageHandler2(MessageHandler);
   message_queue_debugger_thread.Start();
 
   const char* source_1 = "a = 3; b = 4; c = new Object(); c.d = 5;";
   const char* source_2 = "e = 17;";
   const char* source_3 = "a = 4; debugger; a = 5; a = 6; a = 7;";
 
   // See MessageQueueDebuggerThread::Run for interleaved sequence of
   // API calls and events in the two threads.
   CompileRun(source_1);
@@ skipping 215 matching lines @@
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_1, buffer));
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_2, buffer));
 }
 
 
 TEST(ThreadedDebugging) {
   DebuggerThread debugger_thread;
   V8Thread v8_thread;
 
   // Create a V8 environment
-  threaded_debugging_barriers.Initialize();
-
   v8_thread.Start();
   debugger_thread.Start();
 
   v8_thread.Join();
   debugger_thread.Join();
 }
 
 
 /* Test RecursiveBreakpoints */
 /* In this test, the debugger evaluates a function with a breakpoint, after
@@ skipping 25 matching lines @@
 int evaluate_int_result;
 
 static void BreakpointsMessageHandler(const v8::Debug::Message& message) {
   static char print_buffer[1000];
   v8::String::Value json(message.GetJSON());
   Utf16ToAscii(*json, json.length(), print_buffer);
 
   if (IsBreakEventMessage(print_buffer)) {
     break_event_breakpoint_id =
         GetBreakpointIdFromBreakEventMessage(print_buffer);
-    breakpoints_barriers->semaphore_1->Signal();
+    breakpoints_barriers->semaphore_1.Signal();
   } else if (IsEvaluateResponseMessage(print_buffer)) {
     evaluate_int_result = GetEvaluateIntResult(print_buffer);
-    breakpoints_barriers->semaphore_1->Signal();
+    breakpoints_barriers->semaphore_1.Signal();
   }
 }
 
 
 void BreakpointsV8Thread::Run() {
   const char* source_1 = "var y_global = 3;\n"
     "function cat( new_value ) {\n"
     "  var x = new_value;\n"
     "  y_global = y_global + 4;\n"
     "  x = 3 * x + 1;\n"
@@ skipping 88 matching lines @@
 
   // v8 thread initializes, runs source_1
   breakpoints_barriers->barrier_1.Wait();
   // 1:Set breakpoint in cat() (will get id 1).
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_1, buffer));
   // 2:Set breakpoint in dog() (will get id 2).
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_2, buffer));
   breakpoints_barriers->barrier_2.Wait();
   // V8 thread starts compiling source_2.
   // Automatic break happens, to run queued commands
-  // breakpoints_barriers->semaphore_1->Wait();
+  // breakpoints_barriers->semaphore_1.Wait();
   // Commands 1 through 3 run, thread continues.
   // v8 thread runs source_2 to breakpoint in cat().
   // message callback receives break event.
-  breakpoints_barriers->semaphore_1->Wait();
+  breakpoints_barriers->semaphore_1.Wait();
   // Must have hit breakpoint #1.
   CHECK_EQ(1, break_event_breakpoint_id);
   // 4:Evaluate dog() (which has a breakpoint).
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_3, buffer));
   // V8 thread hits breakpoint in dog().
-  breakpoints_barriers->semaphore_1->Wait();  // wait for break event
+  breakpoints_barriers->semaphore_1.Wait();  // wait for break event
   // Must have hit breakpoint #2.
   CHECK_EQ(2, break_event_breakpoint_id);
   // 5:Evaluate (x + 1).
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_4, buffer));
   // Evaluate (x + 1) finishes.
-  breakpoints_barriers->semaphore_1->Wait();
+  breakpoints_barriers->semaphore_1.Wait();
   // Must have result 108.
   CHECK_EQ(108, evaluate_int_result);
   // 6:Continue evaluation of dog().
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_5, buffer));
   // Evaluate dog() finishes.
-  breakpoints_barriers->semaphore_1->Wait();
+  breakpoints_barriers->semaphore_1.Wait();
   // Must have result 107.
   CHECK_EQ(107, evaluate_int_result);
   // 7:Continue evaluation of source_2, finish cat(17), hit breakpoint
   // in cat(19).
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_6, buffer));
   // Message callback gets break event.
-  breakpoints_barriers->semaphore_1->Wait();  // wait for break event
+  breakpoints_barriers->semaphore_1.Wait();  // wait for break event
   // Must have hit breakpoint #1.
   CHECK_EQ(1, break_event_breakpoint_id);
   // 8: Evaluate dog() with breaks disabled.
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_7, buffer));
   // Evaluate dog() finishes.
-  breakpoints_barriers->semaphore_1->Wait();
+  breakpoints_barriers->semaphore_1.Wait();
   // Must have result 116.
   CHECK_EQ(116, evaluate_int_result);
   // 9: Continue evaluation of source2, reach end.
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_8, buffer));
 }
 
 
 void TestRecursiveBreakpointsGeneric(bool global_evaluate) {
   i::FLAG_debugger_auto_break = true;
 
   BreakpointsDebuggerThread breakpoints_debugger_thread(global_evaluate);
   BreakpointsV8Thread breakpoints_v8_thread;
 
   // Create a V8 environment
   Barriers stack_allocated_breakpoints_barriers;
-  stack_allocated_breakpoints_barriers.Initialize();
   breakpoints_barriers = &stack_allocated_breakpoints_barriers;
 
   breakpoints_v8_thread.Start();
   breakpoints_debugger_thread.Start();
 
   breakpoints_v8_thread.Join();
   breakpoints_debugger_thread.Join();
 }
 
 
@@ skipping 372 matching lines @@
 Barriers* host_dispatch_barriers;
 
 static void HostDispatchMessageHandler(const v8::Debug::Message& message) {
   static char print_buffer[1000];
   v8::String::Value json(message.GetJSON());
   Utf16ToAscii(*json, json.length(), print_buffer);
 }
 
 
 static void HostDispatchDispatchHandler() {
-  host_dispatch_barriers->semaphore_1->Signal();
+  host_dispatch_barriers->semaphore_1.Signal();
 }
 
 
 void HostDispatchV8Thread::Run() {
   const char* source_1 = "var y_global = 3;\n"
     "function cat( new_value ) {\n"
     "  var x = new_value;\n"
     "  y_global = 4;\n"
     "  x = 3 * x + 1;\n"
     "  y_global = 5;\n"
@@ skipping 31 matching lines @@
 
   // v8 thread initializes, runs source_1
   host_dispatch_barriers->barrier_1.Wait();
   // 1: Set breakpoint in cat().
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_1, buffer));
 
   host_dispatch_barriers->barrier_2.Wait();
   // v8 thread starts compiling source_2.
   // Break happens, to run queued commands and host dispatches.
   // Wait for host dispatch to be processed.
-  host_dispatch_barriers->semaphore_1->Wait();
+  host_dispatch_barriers->semaphore_1.Wait();
   // 2: Continue evaluation
   v8::Debug::SendCommand(buffer, AsciiToUtf16(command_2, buffer));
 }
 
 
 TEST(DebuggerHostDispatch) {
   HostDispatchDebuggerThread host_dispatch_debugger_thread;
   HostDispatchV8Thread host_dispatch_v8_thread;
   i::FLAG_debugger_auto_break = true;
 
   // Create a V8 environment
   Barriers stack_allocated_host_dispatch_barriers;
-  stack_allocated_host_dispatch_barriers.Initialize();
   host_dispatch_barriers = &stack_allocated_host_dispatch_barriers;
 
   host_dispatch_v8_thread.Start();
   host_dispatch_debugger_thread.Start();
 
   host_dispatch_v8_thread.Join();
   host_dispatch_debugger_thread.Join();
 }
 
 
@@ skipping 13 matching lines @@
  public:
   DebugMessageDispatchDebuggerThread()
       : Thread("DebugMessageDispatchDebuggerThread") { }
   void Run();
 };
 
 Barriers* debug_message_dispatch_barriers;
 
 
 static void DebugMessageHandler() {
-  debug_message_dispatch_barriers->semaphore_1->Signal();
+  debug_message_dispatch_barriers->semaphore_1.Signal();
 }
 
 
 void DebugMessageDispatchV8Thread::Run() {
   v8::V8::Initialize();
   DebugLocalContext env;
   v8::HandleScope scope(env->GetIsolate());
 
   // Set up debug message dispatch handler.
   v8::Debug::SetDebugMessageDispatchHandler(DebugMessageHandler);
 
   CompileRun("var y = 1 + 2;\n");
   debug_message_dispatch_barriers->barrier_1.Wait();
-  debug_message_dispatch_barriers->semaphore_1->Wait();
+  debug_message_dispatch_barriers->semaphore_1.Wait();
   debug_message_dispatch_barriers->barrier_2.Wait();
 }
 
 
 void DebugMessageDispatchDebuggerThread::Run() {
   debug_message_dispatch_barriers->barrier_1.Wait();
   SendContinueCommand();
   debug_message_dispatch_barriers->barrier_2.Wait();
 }
 
 
 TEST(DebuggerDebugMessageDispatch) {
   DebugMessageDispatchDebuggerThread debug_message_dispatch_debugger_thread;
   DebugMessageDispatchV8Thread debug_message_dispatch_v8_thread;
 
   i::FLAG_debugger_auto_break = true;
 
   // Create a V8 environment
   Barriers stack_allocated_debug_message_dispatch_barriers;
-  stack_allocated_debug_message_dispatch_barriers.Initialize();
   debug_message_dispatch_barriers =
       &stack_allocated_debug_message_dispatch_barriers;
 
   debug_message_dispatch_v8_thread.Start();
   debug_message_dispatch_debugger_thread.Start();
 
   debug_message_dispatch_v8_thread.Join();
   debug_message_dispatch_debugger_thread.Join();
 }
 
@@ skipping 1615 matching lines @@
 TEST(LiveEditDisabled) {
   v8::internal::FLAG_allow_natives_syntax = true;
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());
   v8::Debug::SetLiveEditEnabled(false);
   CompileRun("%LiveEditCompareStrings('', '')");
 }
 
 
 #endif  // ENABLE_DEBUGGER_SUPPORT