Add option to extend the time we'll wait before dropping into the dummy sandbox on debugger signals

When the proxy's signal polling thread gets a signal from the debugger client, it would normally wait one second for another thread to recognize and consume the signal. This is pretty reasonable, but with a debug build on a heavily loaded system it's very rarely possible for one second to not be long enough. Added a runtime option to extend this, and set it to 3s for the existing debugger server tests.

hphp/runtime/base/runtime_option.cpp

@@ -451,6 +451,7 @@ std::string RuntimeOption::DebuggerRpcHostDomain;
 int RuntimeOption::DebuggerDefaultRpcTimeout = 30;
 std::string RuntimeOption::DebuggerDefaultSandboxPath;
 std::string RuntimeOption::DebuggerStartupDocument;
+int RuntimeOption::DebuggerSignalTimeout = 1;
 
 std::string RuntimeOption::SendmailPath;
 std::string RuntimeOption::MailForceExtraParameters;
@@ -1202,6 +1203,7 @@ void RuntimeOption::Load(Hdf &config, StringVec *overwrites /* = NULL */,
       DebuggerServerPort = debugger["Port"].getUInt16(8089);
       DebuggerDefaultSandboxPath = debugger["DefaultSandboxPath"].getString();
       DebuggerStartupDocument = debugger["StartupDocument"].getString();
+      DebuggerSignalTimeout = debugger["SignalTimeout"].getInt32(1);
 
       DebuggerDefaultRpcPort = debugger["RPC.DefaultPort"].getUInt16(8083);
       DebuggerDefaultRpcAuth = debugger["RPC.DefaultAuth"].getString();

hphp/runtime/base/runtime_option.h

@@ -508,6 +508,7 @@ public:
   static int DebuggerDefaultRpcTimeout;
   static std::string DebuggerDefaultSandboxPath;
   static std::string DebuggerStartupDocument;
+  static int DebuggerSignalTimeout;
 
   // Mail options
   static std::string SendmailPath;

hphp/runtime/debugger/debugger_proxy.cpp

@@ -306,14 +306,15 @@ void DebuggerProxy::startSignalThread() {
 // it will be passed to the dummy sandbox instead.
 void DebuggerProxy::pollSignal() {
   TRACE_RB(2, "DebuggerProxy::pollSignal: starting\n");
+  int signalTimeout = RuntimeOption::DebuggerSignalTimeout;
   while (!m_stopped) {
     sleep(1);
 
-    // after 1 second that no active thread picks up the signal, we send it
-    // to dummy sandbox
-    if (m_signum != CmdSignal::SignalNone && m_dummySandbox) {
+    // After DebuggerSignalTimeout seconds that no active thread picks
+    // up the signal, we send it to dummy sandbox.
+    if ((m_signum != CmdSignal::SignalNone) && m_dummySandbox) {
       Lock lock(m_signumMutex);
-      if (m_signum != CmdSignal::SignalNone) {
+      if ((m_signum != CmdSignal::SignalNone) && (--signalTimeout <= 0)) {
         TRACE_RB(2, "DebuggerProxy::pollSignal: sending to dummy sandbox\n");
         m_dummySandbox->notifySignal(m_signum);
         m_signum = CmdSignal::SignalNone;
@@ -362,11 +363,13 @@ void DebuggerProxy::pollSignal() {
       break;
     }
 
-    m_signum = sig->getSignal();
+    auto newSignum = sig->getSignal();
 
-    if (m_signum != CmdSignal::SignalNone) {
+    if (newSignum != CmdSignal::SignalNone) {
       TRACE_RB(2, "DebuggerProxy::pollSignal: "
                "got interrupt signal from client\n");
+      m_signum = newSignum;
+      signalTimeout = RuntimeOption::DebuggerSignalTimeout;
       Debugger::RequestInterrupt(shared_from_this());
     }
   }

hphp/test/ext/config-debugger-server.hdf

@@ -15,6 +15,7 @@ Eval {
     EnableDebugger = true
     EnableDebuggerServer = true
     StartupDocument = hphpd_startup.php
+    SignalTimeout = 3
   }
 }