Unify Sampler implementation across platforms using signals to suspend thread

src/sampler.cc

 // Copyright 2013 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 51 matching lines @@
 #include "log.h"
 #include "platform.h"
 #include "simulator.h"
 #include "v8threads.h"
 
 
 namespace v8 {
 namespace internal {
 
 
-#if defined(__linux__) || defined(__FreeBSD__) || defined(__OpenBSD__) \
-    || defined(__NetBSD__) || defined(__sun) || defined(__ANDROID__)
+#if defined(USE_SIGNALS)
 
 #if defined(__ANDROID__) && !defined(__BIONIC_HAVE_UCONTEXT_T)
 
 // Not all versions of Android's C library provide ucontext_t.
 // Detect this and provide custom but compatible definitions. Note that these
 // follow the GLibc naming convention to access register values from
 // mcontext_t.
 //
 // See http://code.google.com/p/android/issues/detail?id=34784
 
@@ skipping 56 matching lines @@
   stack_t uc_stack;
   mcontext_t uc_mcontext;
   // Other fields are not used by V8, don't define them here.
 } ucontext_t;
 enum { REG_EBP = 6, REG_ESP = 7, REG_EIP = 14 };
 #endif
 
 #endif  // __ANDROID__ && !defined(__BIONIC_HAVE_UCONTEXT_T)
 
 
-static pthread_t GetThreadID() {
-#if defined(__ANDROID__)
-  // Android's C library provides gettid(2).
-  return gettid();
-#elif defined(__linux__)
-  // Glibc doesn't provide a wrapper for gettid(2).
-  return syscall(SYS_gettid);
-#elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) \
-    || defined(__sun)
-  return pthread_self();
-#endif
-}
-
-
 class Sampler::PlatformData : public Malloced {
  public:
   PlatformData()
-      : vm_tid_(GetThreadID()),
-        vm_tgid_(getpid()),
+      : vm_tid_(pthread_self()),
         profiled_thread_id_(ThreadId::Current()) {}
 
   pthread_t vm_tid() const { return vm_tid_; }
-  int vm_tgid() const { return vm_tgid_; }
   ThreadId profiled_thread_id() { return profiled_thread_id_; }
 
  private:
   pthread_t vm_tid_;
-  const int vm_tgid_;
   ThreadId profiled_thread_id_;
 };
 
 
 static void ProfilerSignalHandler(int signal, siginfo_t* info, void* context) {
 #if defined(__native_client__)
   // As Native Client does not support signal handling, profiling
   // is disabled.
   return;
 #else
@@ skipping 245 matching lines @@
       if (state == SamplerRegistry::HAS_CPU_PROFILING_SAMPLERS) {
 #if defined(USE_SIGNALS)
         if (!signal_handler_installed_) InstallSignalHandler();
 #endif
         SamplerRegistry::IterateActiveSamplers(&DoCpuProfile, this);
       } else {
 #if defined(USE_SIGNALS)
         if (signal_handler_installed_) RestoreSignalHandler();
 #endif
       }
-      Sleep();  // TODO(svenpanne) Figure out if OS:Sleep(interval_) is enough.
+      OS::Sleep(interval_);
     }
   }
 
   static void DoCpuProfile(Sampler* sampler, void* raw_sender) {
     if (!sampler->isolate()->IsInitialized()) return;
     if (!sampler->IsProfiling()) return;
     SamplerThread* sender = reinterpret_cast<SamplerThread*>(raw_sender);
     sender->SampleContext(sampler);
   }
 
 #if defined(USE_SIGNALS)
+
   void SampleContext(Sampler* sampler) {
     if (!signal_handler_installed_) return;
-    Sampler::PlatformData* platform_data = sampler->platform_data();
-    int tid = platform_data->vm_tid();
-    // Glibc doesn't provide a wrapper for tgkill(2).
-#if defined(ANDROID)
-    syscall(__NR_tgkill, platform_data->vm_tgid(), tid, SIGPROF);
-#elif defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__NetBSD__) \
-    || defined(__sun)
-    pthread_kill(tid, SIGPROF);
-#else
-    int result = syscall(SYS_tgkill, platform_data->vm_tgid(), tid, SIGPROF);
+    pthread_t tid = sampler->platform_data()->vm_tid();
+    int result = pthread_kill(tid, SIGPROF);
     USE(result);
     ASSERT(result == 0);
-#endif
-  }
-
-  void Sleep() {
-    // Convert ms to us and subtract 100 us to compensate delays
-    // occuring during signal delivery.
-    useconds_t interval = interval_ * 1000 - 100;
-#if defined(ANDROID)
-    usleep(interval);
-#else
-    int result = usleep(interval);
-#ifdef DEBUG
-    if (result != 0 && errno != EINTR) {
-      fprintf(stderr,
-              "SamplerThread usleep error; interval = %u, errno = %d\n",
-              interval,
-              errno);
-      ASSERT(result == 0 || errno == EINTR);
-    }
-#endif  // DEBUG
-    USE(result);
-#endif  // ANDROID
   }
 
 #elif defined(__MACH__)
 
   void SampleContext(Sampler* sampler) {
     thread_act_t profiled_thread = sampler->platform_data()->profiled_thread();
     Isolate* isolate = sampler->isolate();
 #if defined(USE_SIMULATOR)
 #if V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_MIPS
     ThreadId thread_id = sampler->platform_data()->profiled_thread_id();
@@ skipping 53 matching lines @@
       sample->sp = reinterpret_cast<Address>(state.REGISTER_FIELD(sp));
       sample->fp = reinterpret_cast<Address>(state.REGISTER_FIELD(bp));
 #endif  // USE_SIMULATOR
 #undef REGISTER_FIELD
       sampler->SampleStack(sample);
       sampler->Tick(sample);
     }
     thread_resume(profiled_thread);
   }
 
-  void Sleep() {
-    OS::Sleep(interval_);
-  }
-
 #elif defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
 
   void SampleContext(Sampler* sampler) {
     HANDLE profiled_thread = sampler->platform_data()->profiled_thread();
     if (profiled_thread == NULL) return;
 
     // Context used for sampling the register state of the profiled thread.
     CONTEXT context;
     memset(&context, 0, sizeof(context));
 
@@ skipping 39 matching lines @@
       sample->sp = reinterpret_cast<Address>(context.Esp);
       sample->fp = reinterpret_cast<Address>(context.Ebp);
 #endif
 #endif  // USE_SIMULATOR
       sampler->SampleStack(sample);
       sampler->Tick(sample);
     }
     ResumeThread(profiled_thread);
   }
 
-  void Sleep() {
-    OS::Sleep(interval_);
-  }
-
 #endif  // USE_SIGNALS
 
   const int interval_;
 
   // Protects the process wide state below.
   static Mutex* mutex_;
   static SamplerThread* instance_;
 #if defined(USE_SIGNALS)
   static bool signal_handler_installed_;
   static struct sigaction old_signal_handler_;
@@ skipping 49 matching lines @@
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 void Sampler::SampleStack(TickSample* sample) {
   StackTracer::Trace(isolate_, sample);
   if (++samples_taken_ < 0) samples_taken_ = 0;
 }
 
 } }  // namespace v8::internal