tor-browser

commit 0d00dcebfc31aec0a6b157700029528ba2806b97
parent 821c617b840ccd2fee25fef090fcf6045e8e1f0f
Author: Nazım Can Altınova <canaltinova@gmail.com>
Date:   Tue, 21 Oct 2025 21:15:35 +0000

Bug 1979114 - Stream SourceTable for each process r=mstange,profiler-reviewers

This table keeps [uuid, filename] mapping for each source, and each
location string will include the index into source table for the
individual source for the JS frames.

Differential Revision: https://phabricator.services.mozilla.com/D266234

Diffstat:
M
tools/profiler/core/ProfileBuffer.h
 | 
9
+++++++++
M
tools/profiler/core/ProfileBufferEntry.cpp
 | 
48
++++++++++++++++++++++++++++++++++++++++++++++++
M
tools/profiler/core/ProfileBufferEntry.h
 | 
5
+++++
M
tools/profiler/core/platform.cpp
 | 
8
++++++++

4 files changed, 70 insertions(+), 0 deletions(-)
diff --git a/tools/profiler/core/ProfileBuffer.h b/tools/profiler/core/ProfileBuffer.h
@@ -13,10 +13,13 @@
 #include "mozilla/PowerOfTwo.h"
 #include "mozilla/ProfileBufferChunkManagerSingle.h"
 #include "mozilla/ProfileChunkedBuffer.h"
+#include "nsTHashMap.h"
 
 class ProcessStreamingContext;
 class RunningTimes;
 
+struct ProfilerJSSourceData;
+
 // Class storing most profiling data in a ProfileChunkedBuffer.
 //
 // This class is used as a queue of entries which, after construction, never
@@ -96,6 +99,12 @@ class ProfileBuffer final {
                             double aSinceTime,
                             mozilla::ProgressLogger aProgressLogger) const;
 
+  // Stream JavaScript source table to JSON and return mapping from sourceId
+  // to index into source table.
+  nsTHashMap<SourceId, IndexIntoSourceTable> StreamSourceTableToJSON(
+      SpliceableJSONWriter& aWriter,
+      const nsTArray<mozilla::JSSourceEntry>& aJSSourceEntries) const;
+
   // Find (via |aLastSample|) the most recent sample for the thread denoted by
   // |aThreadId| and clone it, patching in the current time as appropriate.
   // Mutate |aLastSample| to point to the newly inserted sample.
diff --git a/tools/profiler/core/ProfileBufferEntry.cpp b/tools/profiler/core/ProfileBufferEntry.cpp
@@ -2512,5 +2512,53 @@ void ProfileBuffer::DiscardSamplesBeforeTime(double aTime) {
   (void)aTime;
 }
 
+nsTHashMap<SourceId, IndexIntoSourceTable>
+ProfileBuffer::StreamSourceTableToJSON(
+    SpliceableJSONWriter& aWriter,
+    const nsTArray<mozilla::JSSourceEntry>& aJSSourceEntries) const {
+  enum Schema : uint32_t { UUID = 0, FILENAME = 1 };
+  nsTHashMap<SourceId, IndexIntoSourceTable> sourceIdToIndexMap;
+
+  aWriter.StartObjectProperty("sources");
+  {
+    // Write the schema
+    {
+      JSONSchemaWriter schema(aWriter);
+      schema.WriteField("uuid");
+      schema.WriteField("filename");
+    }
+
+    // Write data array and build sourceId-to-index mapping
+    aWriter.StartArrayProperty("data");
+    uint32_t index = 0;
+    for (const auto& entry : aJSSourceEntries) {
+      // Build sourceId-to-index mapping
+      if (entry.sourceData.sourceId() != 0) {
+        MOZ_ASSERT(!sourceIdToIndexMap.Contains(entry.sourceData.sourceId()),
+                   "Duplicate sourceId detected! This indicates sourceId "
+                   "collision between different sources.");
+        sourceIdToIndexMap.InsertOrUpdate(entry.sourceData.sourceId(), index);
+      }
+
+      // Write [uuid, filename] entry
+      aWriter.StartArrayElement();
+      {
+        // TODO: Use AutoArraySchemaWithStringsWriter to write string indexes
+        // into string table once we have "process global" string table.
+        // Currently string tables are per-thread.
+        aWriter.StringElement(MakeStringSpan(entry.uuid.get()));
+        aWriter.StringElement(MakeStringSpan(entry.sourceData.filePath()));
+      }
+      aWriter.EndArray();
+
+      index++;
+    }
+    aWriter.EndArray();
+  }
+  aWriter.EndObject();
+
+  return sourceIdToIndexMap;
+}
+
 // END ProfileBuffer
 ////////////////////////////////////////////////////////////////////////
diff --git a/tools/profiler/core/ProfileBufferEntry.h b/tools/profiler/core/ProfileBufferEntry.h
@@ -29,6 +29,11 @@
 class ProfilerCodeAddressService;
 struct JSContext;
 
+// Typedef for process-global identifiers for JS script sources.
+using SourceId = uint32_t;
+// Typedef for indexes into the source table array.
+using IndexIntoSourceTable = uint32_t;
+
 class ProfileBufferEntry {
  public:
   using KindUnderlyingType =
diff --git a/tools/profiler/core/platform.cpp b/tools/profiler/core/platform.cpp
@@ -3874,6 +3874,14 @@ locked_profiler_stream_json_for_this_process(
   nsTArray<mozilla::JSSourceEntry> jsSourceEntries =
       ActivePS::GatherJSSources(aLock);
 
+  // If there are sources, stream the sources table that is shared between the
+  // threads, and get the UUID to index mappings needed for frame serialization.
+  Maybe<nsTHashMap<SourceId, IndexIntoSourceTable>> sourceIdToIndexMap;
+  if (!jsSourceEntries.IsEmpty()) {
+    sourceIdToIndexMap.emplace(
+        buffer.StreamSourceTableToJSON(aWriter, jsSourceEntries));
+  }
+
   // Lists the samples for each thread profile
   aWriter.StartArrayProperty("threads");
   {