Optimize the message queue for many active ports with few messages.

runtime/vm/message_handler_test.cc

Index: runtime/vm/message_handler_test.cc
diff --git a/runtime/vm/message_handler_test.cc b/runtime/vm/message_handler_test.cc
index 57eeb342a71ef401a4b75a317be6d887053d46c8..c2724118f38234b5f4b1e3b314d44ed13eb53336 100644
--- a/runtime/vm/message_handler_test.cc
+++ b/runtime/vm/message_handler_test.cc
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/message_handler.h"
+#include "vm/port.h"
 #include "vm/unit_test.h"
 
 namespace dart {
@@ -32,14 +33,17 @@ class MessageHandlerTestPeer {
 class TestMessageHandler : public MessageHandler {
  public:
   TestMessageHandler()
-      : port_buffer_(strdup("")),
+      : port_buffer_(NULL),
+        port_buffer_size_(0),
         notify_count_(0),
         message_count_(0),
+        start_called_(false),
+        end_called_(false),
         result_(true) {
   }
 
   ~TestMessageHandler() {
-    free(port_buffer_);
+    delete[] port_buffer_;
   }
 
   void MessageNotify(Message::Priority priority) {
@@ -47,55 +51,51 @@ class TestMessageHandler : public MessageHandler {
   }
 
   bool HandleMessage(Message* message) {
-    // For testing purposes, keep a string with a list of the ports
+    // For testing purposes, keep a list of the ports
     // for all messages we receive.
-    intptr_t len =
-        OS::SNPrint(NULL, 0, "%s %"Pd64"",
-                    port_buffer_,
-                    message->dest_port()) + 1;
-    char* buffer = reinterpret_cast<char*>(malloc(len));
-    OS::SNPrint(buffer, len, "%s %"Pd64"",
-                port_buffer_,
-                message->dest_port());
-    free(port_buffer_);
-    port_buffer_ = buffer;
+    AddPortToBuffer(message->dest_port());
     delete message;
     message_count_++;
     return result_;
   }
 
-
   bool Start() {
-    intptr_t len =
-        OS::SNPrint(NULL, 0, "%s start", port_buffer_) + 1;
-    char* buffer = reinterpret_cast<char*>(malloc(len));
-    OS::SNPrint(buffer, len, "%s start", port_buffer_);
-    free(port_buffer_);
-    port_buffer_ = buffer;
+    start_called_ = true;
     return true;
   }
 
-
   void End() {
-    intptr_t len =
-        OS::SNPrint(NULL, 0, "%s end", port_buffer_) + 1;
-    char* buffer = reinterpret_cast<char*>(malloc(len));
-    OS::SNPrint(buffer, len, "%s end", port_buffer_);
-    free(port_buffer_);
-    port_buffer_ = buffer;
+    end_called_ = true;
+    AddPortToBuffer(-2);
   }
 
-
-  const char* port_buffer() const { return port_buffer_; }
+  Dart_Port* port_buffer() const { return port_buffer_; }
   int notify_count() const { return notify_count_; }
   int message_count() const { return message_count_; }
+  bool start_called() const { return start_called_; }
+  bool end_called() const { return end_called_; }
 
   void set_result(bool result) { result_ = result; }
 
  private:
-  char* port_buffer_;
+  void AddPortToBuffer(Dart_Port port) {
+    if (port_buffer_ == NULL) {
+      port_buffer_ = new Dart_Port[10];
+      port_buffer_size_ = 10;
+    } else if (message_count_ == port_buffer_size_) {
+      port_buffer_size_ = 2 * port_buffer_size_;
+      delete[] port_buffer_;
+      port_buffer_ = new Dart_Port[port_buffer_size_];
+    }
+    port_buffer_[message_count_] = port;
+  }
+
+  Dart_Port* port_buffer_;
+  int port_buffer_size_;
   int notify_count_;
   int message_count_;
+  bool start_called_;
+  bool end_called_;
   bool result_;
 
   DISALLOW_COPY_AND_ASSIGN(TestMessageHandler);
@@ -153,9 +153,10 @@ UNIT_TEST_CASE(MessageHandler_ClosePort) {
 
   handler_peer.ClosePort(1);
 
-  // The message on port 1 is dropped from the queue.
+  // Closing the port does not drop the messages from the queue.
+  EXPECT(message1 == handler_peer.queue()->Dequeue());
   EXPECT(message2 == handler_peer.queue()->Dequeue());
-  EXPECT(NULL == handler_peer.queue()->Dequeue());
+  delete message1;
   delete message2;
 }
 
@@ -178,43 +179,58 @@ UNIT_TEST_CASE(MessageHandler_CloseAllPorts) {
 UNIT_TEST_CASE(MessageHandler_HandleNextMessage) {
   TestMessageHandler handler;
   MessageHandlerTestPeer handler_peer(&handler);
-  Message* message1 = new Message(1, 0, NULL, 0, Message::kNormalPriority);
+  Dart_Port port1 = PortMap::CreatePort(&handler);
+  Dart_Port port2 = PortMap::CreatePort(&handler);
+  Dart_Port port3 = PortMap::CreatePort(&handler);
+  Message* message1 = new Message(port1, 0, NULL, 0, Message::kNormalPriority);
   handler_peer.PostMessage(message1);
-  Message* oob_message1 = new Message(3, 0, NULL, 0, Message::kOOBPriority);
+  Message* oob_message1 = new Message(port2, 0, NULL, 0, Message::kOOBPriority);
   handler_peer.PostMessage(oob_message1);
-  Message* message2 = new Message(2, 0, NULL, 0, Message::kNormalPriority);
+  Message* message2 = new Message(port2, 0, NULL, 0, Message::kNormalPriority);
   handler_peer.PostMessage(message2);
-  Message* oob_message2 = new Message(4, 0, NULL, 0, Message::kOOBPriority);
+  Message* oob_message2 = new Message(port3, 0, NULL, 0, Message::kOOBPriority);
   handler_peer.PostMessage(oob_message2);
 
   // We handle both oob messages and a single normal message.
   EXPECT(handler.HandleNextMessage());
-  EXPECT_STREQ(" 3 4 1", handler.port_buffer());
-  handler_peer.CloseAllPorts();
+  EXPECT_EQ(3, handler.message_count());
+  Dart_Port* ports = handler.port_buffer();
+  EXPECT_EQ(port2, ports[0]);
+  EXPECT_EQ(port3, ports[1]);
+  EXPECT_EQ(port1, ports[2]);
+  PortMap::ClosePorts(&handler);
 }
 
 
 UNIT_TEST_CASE(MessageHandler_HandleOOBMessages) {
   TestMessageHandler handler;
   MessageHandlerTestPeer handler_peer(&handler);
-  Message* message1 = new Message(1, 0, NULL, 0, Message::kNormalPriority);
+  Dart_Port port1 = PortMap::CreatePort(&handler);
+  Dart_Port port2 = PortMap::CreatePort(&handler);
+  Dart_Port port3 = PortMap::CreatePort(&handler);
+  Dart_Port port4 = PortMap::CreatePort(&handler);
+  Message* message1 = new Message(port1, 0, NULL, 0, Message::kNormalPriority);
   handler_peer.PostMessage(message1);
-  Message* message2 = new Message(2, 0, NULL, 0, Message::kNormalPriority);
+  Message* message2 = new Message(port2, 0, NULL, 0, Message::kNormalPriority);
   handler_peer.PostMessage(message2);
-  Message* oob_message1 = new Message(3, 0, NULL, 0, Message::kOOBPriority);
+  Message* oob_message1 = new Message(port3, 0, NULL, 0, Message::kOOBPriority);
   handler_peer.PostMessage(oob_message1);
-  Message* oob_message2 = new Message(4, 0, NULL, 0, Message::kOOBPriority);
+  Message* oob_message2 = new Message(port4, 0, NULL, 0, Message::kOOBPriority);
   handler_peer.PostMessage(oob_message2);
 
   // We handle both oob messages but no normal messages.
   EXPECT(handler.HandleOOBMessages());
-  EXPECT_STREQ(" 3 4", handler.port_buffer());
+  EXPECT_EQ(2, handler.message_count());
+  Dart_Port* ports = handler.port_buffer();
+  EXPECT_EQ(port3, ports[0]);
+  EXPECT_EQ(port4, ports[1]);
   handler_peer.CloseAllPorts();
 }
 
 
 struct ThreadStartInfo {
   MessageHandler* handler;
+  Dart_Port* ports;
   int count;
 };
 
@@ -224,7 +240,8 @@ static void SendMessages(uword param) {
   MessageHandler* handler = info->handler;
   MessageHandlerTestPeer handler_peer(handler);
   for (int i = 0; i < info->count; i++) {
-    Message* message = new Message(i + 1, 0, NULL, 0, Message::kNormalPriority);
+    Message* message =
+        new Message(info->ports[i], 0, NULL, 0, Message::kNormalPriority);
     handler_peer.PostMessage(message);
   }
 }
@@ -244,7 +261,8 @@ UNIT_TEST_CASE(MessageHandler_Run) {
               TestStartFunction,
               TestEndFunction,
               reinterpret_cast<uword>(&handler));
-  Message* message = new Message(100, 0, NULL, 0, Message::kNormalPriority);
+  Dart_Port port = PortMap::CreatePort(&handler);
+  Message* message = new Message(port, 0, NULL, 0, Message::kNormalPriority);
   handler_peer.PostMessage(message);
 
   // Wait for the first message to be handled.
@@ -252,21 +270,36 @@ UNIT_TEST_CASE(MessageHandler_Run) {
     OS::Sleep(10);
     sleep += 10;
   }
-  EXPECT_STREQ(" start 100", handler.port_buffer());
+  EXPECT_EQ(1, handler.message_count());
+  EXPECT(handler.start_called());
+  EXPECT(!handler.end_called());
+  Dart_Port* handler_ports = handler.port_buffer();
+  EXPECT_EQ(port, handler_ports[0]);
 
   // Start a thread which sends more messages.
+  Dart_Port* ports = new Dart_Port[10];
+  for (int i = 0; i < 10; i++) {
+    ports[i] = PortMap::CreatePort(&handler);
+  }
   ThreadStartInfo info;
   info.handler = &handler;
+  info.ports = ports;
   info.count = 10;
   Thread::Start(SendMessages, reinterpret_cast<uword>(&info));
   while (sleep < kMaxSleep && handler.message_count() < 11) {
     OS::Sleep(10);
     sleep += 10;
   }
-  EXPECT_STREQ(" start 100 1 2 3 4 5 6 7 8 9 10", handler.port_buffer());
-
+  EXPECT_EQ(11, handler.message_count());
+  EXPECT(handler.start_called());
+  EXPECT(!handler.end_called());
+  EXPECT_EQ(port, handler_ports[0]);
+  for (int i = 1; i < 11; i++) {
+    EXPECT_EQ(ports[i - 1], handler_ports[i]);
+  }
   handler_peer.decrement_live_ports();
   EXPECT(!handler.HasLivePorts());
+  PortMap::ClosePorts(&handler);
 }
 
 }  // namespace dart