Add callstats.py run --refresh flag

src/runtime/runtime-internal.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/ast/prettyprinter.h"
 #include "src/bootstrapper.h"
 #include "src/conversions.h"
@@ skipping 532 matching lines @@
   if (args.length() == 0) {
     // Without arguments, the result is returned as a string.
     DCHECK_EQ(0, args.length());
     std::stringstream stats_stream;
     isolate->counters()->runtime_call_stats()->Print(stats_stream);
     Handle<String> result = isolate->factory()->NewStringFromAsciiChecked(
         stats_stream.str().c_str());
     isolate->counters()->runtime_call_stats()->Reset();
     return *result;
   } else {
-    DCHECK_EQ(1, args.length());
+    DCHECK_LE(args.length(), 2);
     std::FILE* f;
     if (args[0]->IsString()) {
       // With a string argument, the results are appended to that file.
       CONVERT_ARG_HANDLE_CHECKED(String, arg0, 0);
       String::FlatContent flat = arg0->GetFlatContent();
       const char* filename =
           reinterpret_cast<const char*>(&(flat.ToOneByteVector()[0]));
       f = std::fopen(filename, "a");
       DCHECK_NOT_NULL(f);
     } else {
       // With an integer argument, the results are written to stdout/stderr.
       CONVERT_SMI_ARG_CHECKED(fd, 0);
       DCHECK(fd == 1 || fd == 2);
       f = fd == 1 ? stdout : stderr;
     }
+    // The second argument (if any) is a message header to be printed.
+    if (args.length() >= 2) {
+      CONVERT_ARG_HANDLE_CHECKED(String, arg1, 1);
+      arg1->PrintOn(f);
+      std::fputc('\n', f);
+      std::fflush(f);
+    }
     OFStream stats_stream(f);
     isolate->counters()->runtime_call_stats()->Print(stats_stream);
     isolate->counters()->runtime_call_stats()->Reset();
     if (args[0]->IsString())
       std::fclose(f);
     else
       std::fflush(f);
     return isolate->heap()->undefined_value();
   }
 }
 
 RUNTIME_FUNCTION(Runtime_EnqueueMicrotask) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, microtask, 0);
   isolate->EnqueueMicrotask(microtask);
   return isolate->heap()->undefined_value();
 }
 
 RUNTIME_FUNCTION(Runtime_RunMicrotasks) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 0);
   isolate->RunMicrotasks();
   return isolate->heap()->undefined_value();
 }
 }  // namespace internal
 }  // namespace v8