Add VMMetric and some sample metrics

runtime/vm/json_stream.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/json_stream.h"
 #include "vm/message.h"
+#include "vm/metrics.h"
 #include "vm/object.h"
 #include "vm/unicode.h"
 
 
 namespace dart {
 
 DECLARE_FLAG(bool, trace_service);
 
 JSONStream::JSONStream(intptr_t buf_size)
     : open_objects_(0),
@@ skipping 231 matching lines @@
   bpt->PrintJSON(this);
 }
 
 
 void JSONStream::PrintValue(const DebuggerEvent* event) {
   PrintCommaIfNeeded();
   event->PrintJSON(this);
 }
 
 
+void JSONStream::PrintValue(Metric* metric) {
+  PrintCommaIfNeeded();
+  metric->PrintJSON(this);
+}
+
+
 void JSONStream::PrintValue(Isolate* isolate, bool ref) {
   PrintCommaIfNeeded();
   isolate->PrintJSON(this, ref);
 }
 
 
 void JSONStream::PrintPropertyBool(const char* name, bool b) {
   PrintPropertyName(name);
   PrintValueBool(b);
 }
@@ skipping 34 matching lines @@
   PrintValue(event);
 }
 
 
 void JSONStream::PrintProperty(const char* name, SourceBreakpoint* bpt) {
   PrintPropertyName(name);
   PrintValue(bpt);
 }
 
 
+void JSONStream::PrintProperty(const char* name, Metric* metric) {
+  PrintPropertyName(name);
+  PrintValue(metric);
+}
+
 void JSONStream::PrintProperty(const char* name, Isolate* isolate) {
   PrintPropertyName(name);
   PrintValue(isolate);
 }
 
 
 void JSONStream::PrintfProperty(const char* name, const char* format, ...) {
   PrintPropertyName(name);
   va_list args;
   va_start(args, format);
@@ skipping 63 matching lines @@
   intptr_t length = buffer_.length();
   if (length == 0) {
     return false;
   }
   char ch = buffer[length-1];
   return (ch != '[') && (ch != '{') && (ch != ':') && (ch != ',');
 }
 
 
 void JSONStream::AddEscapedUTF8String(const char* s) {
+  if (s == NULL) {
+    return;
+  }
   intptr_t len = strlen(s);
   const uint8_t* s8 = reinterpret_cast<const uint8_t*>(s);
   intptr_t i = 0;
   for (; i < len; ) {
     // Extract next UTF8 character.
     int32_t ch = 0;
     int32_t ch_len = Utf8::Decode(&s8[i], len - i, &ch);
     ASSERT(ch_len != 0);
     buffer_.AddEscapedChar(ch);
     // Move i forward.
@@ skipping 38 matching lines @@
   intptr_t len2 = OS::VSNPrint(p, len+1, format, args);
   va_end(args);
   ASSERT(len == len2);
   stream_->buffer_.AddChar('"');
   stream_->AddEscapedUTF8String(p);
   stream_->buffer_.AddChar('"');
   free(p);
 }
 
 }  // namespace dart