Bug 1569506 - SamplerThread can own a Sampler instead of being one - r=canaltinova

`SamplerThread` inheriting from `Sampler` was a bit confusing, and scary with no
virtual destructor&functions.
`SamplerThread` only uses `Sampler`'s `Disable()` and
`SuspendAndSampleAndResumeThread()` functions, and `SamplerThread` is never
accessed through a `Sampler` reference/pointer.
So `SamplerThread` can just own a `Sampler` to make that relationship clearer.

Differential Revision: https://phabricator.services.mozilla.com/D39640

--HG--
extra : moz-landing-system : lando

mozglue/baseprofiler/core/platform-linux-android.cpp

@@ -387,7 +387,7 @@ static void* ThreadEntry(void* aArg) {
 
 SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                              double aIntervalMilliseconds)
-    : Sampler(aLock),
+    : mSampler(aLock),
       mActivityGeneration(aActivityGeneration),
       mIntervalMicroseconds(
           std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))) {
@@ -451,7 +451,7 @@ void SamplerThread::Stop(PSLockRef aLock) {
   // though this SamplerThread is still alive, because the next time the main
   // loop of Run() iterates it won't get past the mActivityGeneration check,
   // and so won't send any signals.
-  Sampler::Disable(aLock);
+  mSampler.Disable(aLock);
 }
 
 // END SamplerThread target specifics

mozglue/baseprofiler/core/platform-macos.cpp

@@ -153,7 +153,7 @@ static void* ThreadEntry(void* aArg) {
 
 SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                              double aIntervalMilliseconds)
-    : Sampler(aLock),
+    : mSampler(aLock),
       mActivityGeneration(aActivityGeneration),
       mIntervalMicroseconds(
           std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))),
@@ -174,7 +174,7 @@ void SamplerThread::SleepMicro(uint32_t aMicroseconds) {
   // case where the usleep call is interrupted by a signal.
 }
 
-void SamplerThread::Stop(PSLockRef aLock) { Sampler::Disable(aLock); }
+void SamplerThread::Stop(PSLockRef aLock) { mSampler.Disable(aLock); }
 
 // END SamplerThread target specifics
 ////////////////////////////////////////////////////////////////////////

mozglue/baseprofiler/core/platform-win32.cpp

@@ -200,7 +200,7 @@ static unsigned int __stdcall ThreadEntry(void* aArg) {
 
 SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                              double aIntervalMilliseconds)
-    : Sampler(aLock),
+    : mSampler(aLock),
       mActivityGeneration(aActivityGeneration),
       mIntervalMicroseconds(
           std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))) {
@@ -267,7 +267,7 @@ void SamplerThread::Stop(PSLockRef aLock) {
     ::timeEndPeriod(mIntervalMicroseconds / 1000);
   }
 
-  Sampler::Disable(aLock);
+  mSampler.Disable(aLock);
 }
 
 // END SamplerThread target specifics

mozglue/baseprofiler/core/platform.cpp

@@ -983,8 +983,8 @@ class Registers {
   void Clear() { memset(this, 0, sizeof(*this)); }
 
   // These fields are filled in by
-  // SamplerThread::SuspendAndSampleAndResumeThread() for periodic and
-  // backtrace samples, and by SyncPopulate() for synchronous samples.
+  // Sampler::SuspendAndSampleAndResumeThread() for periodic and backtrace
+  // samples, and by SyncPopulate() for synchronous samples.
   Address mPC;  // Instruction pointer.
   Address mSP;  // Stack pointer.
   Address mFP;  // Frame pointer.
@@ -1885,7 +1885,7 @@ class Sampler {
 // active. It periodically runs through all registered threads, finds those
 // that should be sampled, then pauses and samples them.
 
-class SamplerThread : public Sampler {
+class SamplerThread {
  public:
   // Creates a sampler thread, but doesn't start it.
   SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
@@ -1903,6 +1903,9 @@ class SamplerThread : public Sampler {
   // Best effort timing.
   void SleepMicro(uint32_t aMicroseconds);
 
+  // The sampler used to suspend and sample threads.
+  Sampler mSampler;
+
   // The activity generation, for detecting when the sampler thread must stop.
   const uint32_t mActivityGeneration;
 
@@ -2010,7 +2013,7 @@ void SamplerThread::Run() {
           }
 
           now = TimeStamp::NowUnfuzzed();
-          SuspendAndSampleAndResumeThread(
+          mSampler.SuspendAndSampleAndResumeThread(
               lock, *registeredThread, [&](const Registers& aRegs) {
                 DoPeriodicSample(lock, *registeredThread, *profiledThreadData,
                                  now, aRegs);

tools/profiler/core/platform-linux-android.cpp

@@ -378,7 +378,7 @@ static void* ThreadEntry(void* aArg) {
 
 SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                              double aIntervalMilliseconds)
-    : Sampler(aLock),
+    : mSampler(aLock),
       mActivityGeneration(aActivityGeneration),
       mIntervalMicroseconds(
           std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))) {
@@ -442,7 +442,7 @@ void SamplerThread::Stop(PSLockRef aLock) {
   // though this SamplerThread is still alive, because the next time the main
   // loop of Run() iterates it won't get past the mActivityGeneration check,
   // and so won't send any signals.
-  Sampler::Disable(aLock);
+  mSampler.Disable(aLock);
 }
 
 // END SamplerThread target specifics

tools/profiler/core/platform-macos.cpp

@@ -148,7 +148,7 @@ static void* ThreadEntry(void* aArg) {
 
 SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                              double aIntervalMilliseconds)
-    : Sampler(aLock),
+    : mSampler(aLock),
       mActivityGeneration(aActivityGeneration),
       mIntervalMicroseconds(
           std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))),
@@ -169,7 +169,7 @@ void SamplerThread::SleepMicro(uint32_t aMicroseconds) {
   // case where the usleep call is interrupted by a signal.
 }
 
-void SamplerThread::Stop(PSLockRef aLock) { Sampler::Disable(aLock); }
+void SamplerThread::Stop(PSLockRef aLock) { mSampler.Disable(aLock); }
 
 // END SamplerThread target specifics
 ////////////////////////////////////////////////////////////////////////

tools/profiler/core/platform-win32.cpp

@@ -185,7 +185,7 @@ static unsigned int __stdcall ThreadEntry(void* aArg) {
 
 SamplerThread::SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
                              double aIntervalMilliseconds)
-    : Sampler(aLock),
+    : mSampler(aLock),
       mActivityGeneration(aActivityGeneration),
       mIntervalMicroseconds(
           std::max(1, int(floor(aIntervalMilliseconds * 1000 + 0.5)))) {
@@ -252,7 +252,7 @@ void SamplerThread::Stop(PSLockRef aLock) {
     ::timeEndPeriod(mIntervalMicroseconds / 1000);
   }
 
-  Sampler::Disable(aLock);
+  mSampler.Disable(aLock);
 }
 
 // END SamplerThread target specifics

tools/profiler/core/platform.cpp

@@ -1083,8 +1083,8 @@ class Registers {
   void Clear() { memset(this, 0, sizeof(*this)); }
 
   // These fields are filled in by
-  // SamplerThread::SuspendAndSampleAndResumeThread() for periodic and
-  // backtrace samples, and by SyncPopulate() for synchronous samples.
+  // Sampler::SuspendAndSampleAndResumeThread() for periodic and backtrace
+  // samples, and by SyncPopulate() for synchronous samples.
   Address mPC;  // Instruction pointer.
   Address mSP;  // Stack pointer.
   Address mFP;  // Frame pointer.
@@ -2431,7 +2431,7 @@ class Sampler {
 // active. It periodically runs through all registered threads, finds those
 // that should be sampled, then pauses and samples them.
 
-class SamplerThread : public Sampler {
+class SamplerThread {
  public:
   // Creates a sampler thread, but doesn't start it.
   SamplerThread(PSLockRef aLock, uint32_t aActivityGeneration,
@@ -2449,6 +2449,9 @@ class SamplerThread : public Sampler {
   // Best effort timing.
   void SleepMicro(uint32_t aMicroseconds);
 
+  // The sampler used to suspend and sample threads.
+  Sampler mSampler;
+
   // The activity generation, for detecting when the sampler thread must stop.
   const uint32_t mActivityGeneration;
 
@@ -2578,7 +2581,7 @@ void SamplerThread::Run() {
           }
 
           now = TimeStamp::NowUnfuzzed();
-          SuspendAndSampleAndResumeThread(
+          mSampler.SuspendAndSampleAndResumeThread(
               lock, *registeredThread, [&](const Registers& aRegs) {
                 DoPeriodicSample(lock, *registeredThread, *profiledThreadData,
                                  now, aRegs);