Bug 1745318 - In the parent process, assert that profiles are only generated on the main thread - r=mstange

This is to avoid situations where a developer may call this from another thread, and get a confusingly incomplete profile.

Differential Revision: https://phabricator.services.mozilla.com/D133478

tools/profiler/core/platform.cpp

@@ -3085,7 +3085,8 @@ static void locked_profiler_stream_json_for_this_process(
   buffer.AddEntry(ProfileBufferEntry::CollectionEnd(collectionEndMs));
 }
 
-bool profiler_stream_json_for_this_process(
+// Keep this internal function non-static, so it may be used by tests.
+bool do_profiler_stream_json_for_this_process(
     SpliceableJSONWriter& aWriter, double aSinceTime, bool aIsShuttingDown,
     ProfilerCodeAddressService* aService) {
   LOG("profiler_stream_json_for_this_process");
@@ -3110,6 +3111,17 @@ bool profiler_stream_json_for_this_process(
   return true;
 }
 
+bool profiler_stream_json_for_this_process(
+    SpliceableJSONWriter& aWriter, double aSinceTime, bool aIsShuttingDown,
+    ProfilerCodeAddressService* aService) {
+  MOZ_RELEASE_ASSERT(
+      !XRE_IsParentProcess() || NS_IsMainThread(),
+      "In the parent process, profiles should only be generated from the main "
+      "thread, otherwise they will be incomplete.");
+  return do_profiler_stream_json_for_this_process(aWriter, aSinceTime,
+                                                  aIsShuttingDown, aService);
+}
+
 // END saving/streaming code
 ////////////////////////////////////////////////////////////////////////
 

tools/profiler/tests/gtest/GeckoProfiler.cpp

@@ -3572,6 +3572,13 @@ TEST(GeckoProfiler, StreamJSONForThisProcess)
   ASSERT_TRUE(!::profiler_stream_json_for_this_process(w));
 }
 
+// Internal version of profiler_stream_json_for_this_process, which allows being
+// called from a non-main thread of the parent process, at the risk of getting
+// an incomplete profile.
+bool do_profiler_stream_json_for_this_process(
+    SpliceableJSONWriter& aWriter, double aSinceTime, bool aIsShuttingDown,
+    ProfilerCodeAddressService* aService);
+
 TEST(GeckoProfiler, StreamJSONForThisProcessThreaded)
 {
   // Same as the previous test, but calling some things on background threads.
@@ -3595,7 +3602,10 @@ TEST(GeckoProfiler, StreamJSONForThisProcessThreaded)
           "GeckoProfiler_StreamJSONForThisProcessThreaded_Test::TestBody",
           [&]() {
             w.Start();
-            ASSERT_TRUE(::profiler_stream_json_for_this_process(w));
+            ASSERT_TRUE(::do_profiler_stream_json_for_this_process(
+                w, /* double aSinceTime */ 0.0,
+                /* bool aIsShuttingDown */ false,
+                /* ProfilerCodeAddressService* aService */ nullptr));
             w.End();
           }),
       NS_DISPATCH_SYNC);
@@ -3611,7 +3621,10 @@ TEST(GeckoProfiler, StreamJSONForThisProcessThreaded)
           "GeckoProfiler_StreamJSONForThisProcessThreaded_Test::TestBody",
           [&]() {
             profiler_stop();
-            ASSERT_TRUE(!::profiler_stream_json_for_this_process(w));
+            ASSERT_TRUE(!::do_profiler_stream_json_for_this_process(
+                w, /* double aSinceTime */ 0.0,
+                /* bool aIsShuttingDown */ false,
+                /* ProfilerCodeAddressService* aService */ nullptr));
           }),
       NS_DISPATCH_SYNC);
   thread->Shutdown();