Bug 1145306 - Expose circular buffer status from profiler. r=mstange

tools/profiler/GeckoProfiler.h

@@ -170,6 +170,22 @@ static inline void profiler_save_profile_to_file(char* aFilename) { }
 // Returns a null terminated char* array.
 static inline char** profiler_get_features() { return nullptr; }
 
+// Get information about the current buffer status.
+// Retursn (using outparams) the current write position in the buffer,
+// the total size of the buffer, and the generation of the buffer.
+// This information may be useful to a user-interface displaying the
+// current status of the profiler, allowing the user to get a sense
+// for how fast the buffer is being written to, and how much
+// data is visible.
+static inline void profiler_get_buffer_info(uint32_t *aCurrentPosition,
+                                            uint32_t *aTotalSize,
+                                            uint32_t *aGeneration)
+{
+  *aCurrentPosition = 0;
+  *aTotalSize = 0;
+  *aGeneration = 0;
+}
+
 // Discard the profile, throw away the profile and notify 'profiler-locked'.
 // This function is to be used when entering private browsing to prevent
 // the profiler from collecting sensitive data.

tools/profiler/GeckoProfilerFunc.h

@@ -65,6 +65,9 @@ extern "C" {
 
 const char** mozilla_sampler_get_features();
 
+void mozilla_sampler_get_buffer_info(uint32_t *aCurrentPosition, uint32_t *aTotalSize,
+                                     uint32_t *aGeneration);
+
 void mozilla_sampler_init(void* stackTop);
 
 void mozilla_sampler_shutdown();

tools/profiler/GeckoProfilerImpl.h

@@ -167,6 +167,13 @@ const char** profiler_get_features()
   return mozilla_sampler_get_features();
 }
 
+static inline
+void profiler_get_buffer_info(uint32_t *aCurrentPosition, uint32_t *aTotalSize,
+                              uint32_t *aGeneration)
+{
+  return mozilla_sampler_get_buffer_info(aCurrentPosition, aTotalSize, aGeneration);
+}
+
 static inline
 void profiler_lock()
 {

tools/profiler/TableTicker.cpp

@@ -1079,3 +1079,11 @@ SyncProfile* TableTicker::GetBacktrace()
 
   return profile;
 }
+
+void
+TableTicker::GetBufferInfo(uint32_t *aCurrentPosition, uint32_t *aTotalSize, uint32_t *aGeneration)
+{
+  *aCurrentPosition = mBuffer->mWritePos;
+  *aTotalSize = mBuffer->mEntrySize;
+  *aGeneration = mBuffer->mGeneration;
+}

tools/profiler/TableTicker.h

@@ -210,6 +210,8 @@ class TableTicker: public Sampler {
   bool DisplayListDump() const { return mDisplayListDump; }
   bool ProfileRestyle() const { return mProfileRestyle; }
 
+  void GetBufferInfo(uint32_t *aCurrentPosition, uint32_t *aTotalSize, uint32_t *aGeneration);
+
 protected:
   // Called within a signal. This function must be reentrant
   virtual void InplaceTick(TickSample* sample);

tools/profiler/nsIProfiler.idl

@@ -12,7 +12,7 @@ class nsCString;
 
 [ref] native StringArrayRef(const nsTArray<nsCString>);
 
-[scriptable, uuid(42d1e0e3-303a-424f-89ea-4f15c699d767)]
+[scriptable, uuid(edd65f3f-c2a2-4217-a2e2-40347ba4a2b3)]
 interface nsIProfiler : nsISupports
 {
   void StartProfiler(in uint32_t aEntries, in double aInterval,
@@ -31,6 +31,9 @@ interface nsIProfiler : nsISupports
   boolean IsActive();
   void GetFeatures(out uint32_t aCount, [retval, array, size_is(aCount)] out string aFeatures);
 
+  void GetBufferInfo(out uint32_t aCurrentPosition, out uint32_t aTotalSize,
+                     out uint32_t aGeneration);
+
   /**
    * Returns a JSON string of an array of shared library objects.
    * Every object has three properties: start, end, and name.

tools/profiler/nsProfiler.cpp

@@ -248,3 +248,13 @@ nsProfiler::GetFeatures(uint32_t *aCount, char ***aFeatures)
   *aCount = len;
   return NS_OK;
 }
+
+NS_IMETHODIMP
+nsProfiler::GetBufferInfo(uint32_t *aCurrentPosition, uint32_t *aTotalSize, uint32_t *aGeneration)
+{
+  MOZ_ASSERT(aCurrentPosition);
+  MOZ_ASSERT(aTotalSize);
+  MOZ_ASSERT(aGeneration);
+  profiler_get_buffer_info(aCurrentPosition, aTotalSize, aGeneration);
+  return NS_OK;
+}

tools/profiler/platform.cpp

@@ -650,6 +650,23 @@ const char** mozilla_sampler_get_features()
   return features;
 }
 
+void mozilla_sampler_get_buffer_info(uint32_t *aCurrentPosition, uint32_t *aTotalSize,
+                                     uint32_t *aGeneration)
+{
+  *aCurrentPosition = 0;
+  *aTotalSize = 0;
+  *aGeneration = 0;
+
+  if (!stack_key_initialized)
+    return;
+
+  TableTicker *t = tlsTicker.get();
+  if (!t)
+    return;
+
+  t->GetBufferInfo(aCurrentPosition, aTotalSize, aGeneration);
+}
+
 // Values are only honored on the first start
 void mozilla_sampler_start(int aProfileEntries, double aInterval,
                            const char** aFeatures, uint32_t aFeatureCount,