Bug 1673513 - profiler_get_profile_json(SpliceableChunkedJSONWriter&, ...) - r=florian

The main goal is to separate the profile generation (in a JSONWriter) from the final allocation needed to output the profile in one block.
This will be needed in the next patch, where the profile generation will be done in a new worker thread, but the shmem allocation *must* be done on the original "ProfilerChild" thread that handles IPC responses.

Differential Revision: https://phabricator.services.mozilla.com/D135483

tools/profiler/core/platform.cpp

@@ -5105,24 +5105,37 @@ UniquePtr<char[]> profiler_get_profile(double aSinceTime,
   return b.ChunkedWriteFunc().CopyData();
 }
 
+bool profiler_get_profile_json(
+    SpliceableChunkedJSONWriter& aSpliceableChunkedJSONWriter,
+    double aSinceTime, bool aIsShuttingDown,
+    mozilla::ProgressLogger aProgressLogger) {
+  LOG("profiler_get_profile_json");
+
+  UniquePtr<ProfilerCodeAddressService> service =
+      profiler_code_address_service_for_presymbolication();
+
+  return WriteProfileToJSONWriter(
+      aSpliceableChunkedJSONWriter, aSinceTime, aIsShuttingDown, service.get(),
+      aProgressLogger.CreateSubLoggerFromTo(
+          0.1_pc, "profiler_get_profile_json: WriteProfileToJSONWriter started",
+          99.9_pc, "profiler_get_profile_json: WriteProfileToJSONWriter done"));
+}
+
 void profiler_get_profile_json_into_lazily_allocated_buffer(
     const std::function<char*(size_t)>& aAllocator, double aSinceTime,
     bool aIsShuttingDown, mozilla::ProgressLogger aProgressLogger) {
   LOG("profiler_get_profile_json_into_lazily_allocated_buffer");
 
-  UniquePtr<ProfilerCodeAddressService> service =
-      profiler_code_address_service_for_presymbolication();
-
   SpliceableChunkedJSONWriter b;
-  if (!WriteProfileToJSONWriter(
-          b, aSinceTime, aIsShuttingDown, service.get(),
+  if (!profiler_get_profile_json(
+          b, aSinceTime, aIsShuttingDown,
           aProgressLogger.CreateSubLoggerFromTo(
               1_pc,
               "profiler_get_profile_json_into_lazily_allocated_buffer: "
-              "WriteProfileToJSONWriter started",
+              "profiler_get_profile_json started",
               98_pc,
               "profiler_get_profile_json_into_lazily_allocated_buffer: "
-              "WriteProfileToJSONWriter done"))) {
+              "profiler_get_profile_json done"))) {
     return;
   }
 

tools/profiler/core/platform.h

@@ -35,6 +35,7 @@
 #include "mozilla/Logging.h"
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/ProfileBufferEntrySerialization.h"
+#include "mozilla/ProfileJSONWriter.h"
 #include "mozilla/ProfilerUtils.h"
 #include "mozilla/ProgressLogger.h"
 #include "mozilla/TimeStamp.h"
@@ -84,9 +85,6 @@ typedef uint8_t* Address;
 // future sampling; this is not time critical, nor dependent on anything else.
 extern mozilla::Atomic<int, mozilla::MemoryOrdering::Relaxed> gSkipSampling;
 
-namespace mozilla {
-class JSONWriter;
-}
 void AppendSharedLibraries(mozilla::JSONWriter& aWriter);
 
 // Convert the array of strings to a bitfield.
@@ -94,6 +92,11 @@ uint32_t ParseFeaturesFromStringArray(const char** aFeatures,
                                       uint32_t aFeatureCount,
                                       bool aIsStartup = false);
 
+bool profiler_get_profile_json(
+    SpliceableChunkedJSONWriter& aSpliceableChunkedJSONWriter,
+    double aSinceTime, bool aIsShuttingDown,
+    mozilla::ProgressLogger aProgressLogger);
+
 void profiler_get_profile_json_into_lazily_allocated_buffer(
     const std::function<char*(size_t)>& aAllocator, double aSinceTime,
     bool aIsShuttingDown, mozilla::ProgressLogger aProgressLogger);