Merge the Merlin heap tracing to top-of-trunk.

runtime/bin/main.cc

Index: runtime/bin/main.cc
diff --git a/runtime/bin/main.cc b/runtime/bin/main.cc
index 7505ad1c252bce5910c4c79fb80b5ffddbb201a5..5e72cc3ee2d574504dc099ac9a5652d9a0d1ed1a 100644
--- a/runtime/bin/main.cc
+++ b/runtime/bin/main.cc
@@ -32,6 +32,15 @@ extern const uint8_t* snapshot_buffer;
 static File* perf_events_symbols_file = NULL;
 
 
+// Global state that indicates whether heap tracing is on.
+static bool heap_trace = false;
+
+
+// Global state that indicates the file name prefix to use for heap
+// trace output files.
+static const char* heap_trace_file_prefix = "dart_heap_trace";
+
+
 // Global state that indicates whether pprof symbol information is
 // to be generated or not.
 static const char* generate_pprof_symbols_filename = NULL;
@@ -180,6 +189,20 @@ static bool ProcessPprofOption(const char* filename) {
 }
 
 
+static bool ProcessHeapTraceOption(const char* heap_trace_option) {
+  heap_trace = true;
+  return true;
+}
+
+
+static bool ProcessHeapTraceFilePrefixOption(
+    const char* heap_trace_file_prefix_option) {
+  ASSERT(heap_trace_file_prefix_option != NULL);
+  heap_trace_file_prefix = heap_trace_file_prefix_option;
+  return true;
+}
+
+
 static bool ProcessScriptSnapshotOption(const char* filename) {
   if (filename != NULL && strlen(filename) != 0) {
     use_script_snapshot = true;
@@ -207,6 +230,8 @@ static struct {
   { "--debug", ProcessDebugOption },
   { "--generate_perf_events_symbols", ProcessPerfEventsOption },
   { "--generate_pprof_symbols=", ProcessPprofOption },
+  { "--heap_trace", ProcessHeapTraceOption },
+  { "--heap_trace_file_prefix=", ProcessHeapTraceFilePrefixOption },
   { "--use_script_snapshot=", ProcessScriptSnapshotOption },
   { NULL, NULL }
 };
@@ -232,6 +257,34 @@ static void WriteToPerfEventsFile(const char* buffer, int64_t num_bytes) {
   perf_events_symbols_file->WriteFully(buffer, num_bytes);
 }
 
+
+// This function used by the heap trace to open new trace files, one
+// file per isolate.
+static void* OpenHeapTraceFile(const char* name) {
+  File* file = File::Open(name, File::kWriteTruncate);
+  ASSERT(file != NULL);
+  return reinterpret_cast<void*>(file);
+}
+
+
+// Function used by the heap trace to write to trace files.
+static void WriteToHeapTraceFile(const void* buffer,
+                                 intptr_t num_bytes,
+                                 void* stream) {
+  ASSERT(stream != NULL);
+  File* file_stream = reinterpret_cast<File*>(stream);
+  bool bytes_written = file_stream->WriteFully(buffer, num_bytes);
+  ASSERT(bytes_written);
+}
+
+
+// Function used by the heap trace to close trace files.
+static void CloseHeapTraceFile(void* stream) {
+  File* file_stream = reinterpret_cast<File*>(stream);
+  delete file_stream;  // Closes the file.
+}
+
+
 // Convert all the arguments to UTF8. On Windows, the arguments are
 // encoded in the current code page and not UTF8.
 //
@@ -298,6 +351,13 @@ static int ParseArguments(int argc,
     Dart_InitPprofSupport();
   }
 
+  if (heap_trace) {
+    Dart_InitHeapTrace(&OpenHeapTraceFile,
+                       &WriteToHeapTraceFile,
+                       &CloseHeapTraceFile,
+                       heap_trace_file_prefix);
+  }
+
   // Get the script name.
   if (i < argc) {
     *script_name = argv[i];