Add V8 heap info to process.memoryUsage()

doc/api.txt

@@ -110,7 +110,18 @@ The PID of the process.
 What platform you're running on. +"linux2"+, +"darwin"+, etc.
 
 +process.memoryUsage()+ ::
-Returns the memory usage of the Node process: e.g. +{"rss":5828608,"vsize":3112529920}+
+Returns the memory usage of the Node process. It looks like this
++
+----------------------
+{
+ "rss": 4935680,
+ "vsize": 41893888,
+ "heapTotal": 1826816,
+ "heapUsed": 650472
+}
+----------------------
++
++heapTotal+ and +heapUsed+ refer to V8's memory usage.
 
 +process.exit(code=0)+::
 Ends the process with the specified code. By default it exits with the

src/node.cc

@@ -513,6 +513,14 @@ v8::Handle<v8::Value> MemoryUsage(const v8::Arguments& args) {
   info->Set(String::NewSymbol("rss"), Integer::NewFromUnsigned(rss));
   info->Set(String::NewSymbol("vsize"), Integer::NewFromUnsigned(vsize));
 
+  // V8 memory usage
+  HeapStatistics v8_heap_stats;
+  V8::GetHeapStatistics(&v8_heap_stats);
+  info->Set(String::NewSymbol("heapTotal"),
+            Integer::NewFromUnsigned(v8_heap_stats.total_heap_size()));
+  info->Set(String::NewSymbol("heapUsed"),
+            Integer::NewFromUnsigned(v8_heap_stats.used_heap_size()));
+
   return scope.Close(info);
 #endif
 }