Use CPU time instead of wall time for time limit

Zend PHP does not count in sleeping time into scripts time
limit, HHVM does. Change that for parity reasons.

Closes #1279
Closes #1287

Reviewed By: @markw65

Differential Revision: D1066797

Author: scannell

hphp/doc/options.compiled

@@ -729,6 +729,8 @@ users can use the same machine serving their own source files.
       }
     }
 
+    TimeoutsUseWallTime = true
+
     # experimental, please ignore
     BytecodeInterpreter = false
     DumpBytecode = false
@@ -744,6 +746,11 @@ includes/requires and loading code. This is enabled by default for parity with
 the reference implementation. If not needed for a particular application and/or
 configuration, disable this when tuning.
 
+- TimeoutsUseWallTime
+
+Determines whether or not to interpret set_time_limit timeouts as wall time or
+CPU time (which the reference implementation uses.) Defaults to wall time.
+
 = MySQL
 
   MySQL {

hphp/runtime/base/runtime-option.cpp

@@ -343,6 +343,7 @@ int RuntimeOption::MaxUserFunctionId = (2 * 65536);
 bool RuntimeOption::EnableFinallyStatement = false;
 bool RuntimeOption::EnableArgsInBacktraces = true;
 bool RuntimeOption::EnableZendCompat = false;
+bool RuntimeOption::TimeoutsUseWallTime = true;
 
 int RuntimeOption::GetScannerType() {
   int type = 0;
@@ -1105,6 +1106,7 @@ void RuntimeOption::Load(Hdf &config, StringVec *overwrites /* = NULL */,
     EnableAspTags = eval["EnableAspTags"].getBool();
     EnableXHP = eval["EnableXHP"].getBool(false);
     EnableZendCompat = eval["EnableZendCompat"].getBool(false);
+    TimeoutsUseWallTime = eval["TimeoutsUseWallTime"].getBool(true);
 
     if (EnableHipHopSyntax) {
       // If EnableHipHopSyntax is true, it forces EnableXHP to true

hphp/runtime/base/runtime-option.h

@@ -337,6 +337,7 @@ class RuntimeOption {
   static bool EnableFinallyStatement;
   static bool EnableArgsInBacktraces;
   static bool EnableZendCompat;
+  static bool TimeoutsUseWallTime;
 
   static int GetScannerType();
 

hphp/runtime/base/thread-info.cpp

@@ -145,7 +145,10 @@ void RequestInjectionData::setTimeout(int seconds) {
     sev.sigev_notify = SIGEV_SIGNAL;
     sev.sigev_signo = SIGVTALRM;
     sev.sigev_value.sival_ptr = this;
-    if (timer_create(CLOCK_REALTIME, &sev, &m_timer_id)) {
+    auto const& clockType =
+      RuntimeOption::TimeoutsUseWallTime ? CLOCK_REALTIME :
+                                           CLOCK_THREAD_CPUTIME_ID;
+    if (timer_create(clockType, &sev, &m_timer_id)) {
       raise_error("Failed to set timeout: %s", folly::errnoStr(errno).c_str());
     }
     m_hasTimer = true;