Fix end_to_end_test performance regression caused by using mutexes

net/tools/quic/test_tools/server_thread.cc

Index: net/tools/quic/test_tools/server_thread.cc
diff --git a/net/tools/quic/test_tools/server_thread.cc b/net/tools/quic/test_tools/server_thread.cc
index ecc8ccdd61c8a2a80ef59763d122b51831760a39..e2b6506d17aae2931b1e2939b6017b021d348b78 100644
--- a/net/tools/quic/test_tools/server_thread.cc
+++ b/net/tools/quic/test_tools/server_thread.cc
@@ -15,33 +15,48 @@ ServerThread::ServerThread(IPEndPoint address,
                            const QuicVersionVector& supported_versions,
                            bool strike_register_no_startup_period)
     : SimpleThread("server_thread"),
-      listening_(true, false),
       confirmed_(true, false),
+      pause_(true, false),
+      paused_(true, false),
+      resume_(true, false),
       quit_(true, false),
       server_(config, supported_versions),
       address_(address),
-      port_(0) {
+      port_(0),
+      initialized_(false) {
   if (strike_register_no_startup_period) {
     server_.SetStrikeRegisterNoStartupPeriod();
   }
 }
 
-ServerThread::~ServerThread() {
-}
+ServerThread::~ServerThread() {}
+
+void ServerThread::Initialize() {
+  if (initialized_) {
+    return;
+  }
 
-void ServerThread::Run() {
   server_.Listen(address_);
 
   port_lock_.Acquire();
   port_ = server_.port();
   port_lock_.Release();
 
-  listening_.Signal();
+  initialized_ = true;
+}
+
+void ServerThread::Run() {
+  if (!initialized_) {
+    Initialize();
+  }
+
   while (!quit_.IsSignaled()) {
-    event_loop_mu_.Acquire();
+    if (pause_.IsSignaled() && !resume_.IsSignaled()) {
+      paused_.Signal();
+      resume_.Wait();
+    }
     server_.WaitForEvents();
     MaybeNotifyOfHandshakeConfirmation();
-    event_loop_mu_.Release();
   }
 
   server_.Shutdown();
@@ -51,11 +66,7 @@ int ServerThread::GetPort() {
   port_lock_.Acquire();
   int rc = port_;
   port_lock_.Release();
-    return rc;
-}
-
-void ServerThread::WaitForServerStartup() {
-  listening_.Wait();
+  return rc;
 }
 
 void ServerThread::WaitForCryptoHandshakeConfirmed() {
@@ -63,15 +74,21 @@ void ServerThread::WaitForCryptoHandshakeConfirmed() {
 }
 
 void ServerThread::Pause() {
-  event_loop_mu_.Acquire();
+  DCHECK(!pause_.IsSignaled());
+  pause_.Signal();
+  paused_.Wait();
 }
 
 void ServerThread::Resume() {
-  event_loop_mu_.AssertAcquired();  // Checks the calling thread only!
-  event_loop_mu_.Release();
+  DCHECK(!resume_.IsSignaled());
+  DCHECK(pause_.IsSignaled());
+  resume_.Signal();
 }
 
 void ServerThread::Quit() {
+  if (pause_.IsSignaled() && !resume_.IsSignaled()) {
+    resume_.Signal();
+  }
   quit_.Signal();
 }