v8,src: expose statistics about heap spaces

Provide means to inspect information about the separate heap spaces
via a callable API. This is helpful to analyze memory issues.

Fixes: https://github.com/nodejs/node/issues/2079
PR-URL: https://github.com/nodejs/node/pull/4463
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>

1 files changed, 86 insertions, 1 deletions

diff --git a/src/node_v8.cc b/src/node_v8.cc
index 9f456daec4..a1122e57f1 100644
--- a/src/node_v8.cc
+++ b/src/node_v8.cc
@@ -7,13 +7,16 @@
 
 namespace node {
 
+using v8::Array;
 using v8::ArrayBuffer;
 using v8::Context;
 using v8::Function;
 using v8::FunctionCallbackInfo;
+using v8::HeapSpaceStatistics;
 using v8::HeapStatistics;
 using v8::Isolate;
 using v8::Local;
+using v8::NewStringType;
 using v8::Object;
 using v8::String;
 using v8::Uint32;
@@ -34,6 +37,21 @@ static const size_t kHeapStatisticsPropertiesCount =
     HEAP_STATISTICS_PROPERTIES(V);
 #undef V
 
+#define HEAP_SPACE_STATISTICS_PROPERTIES(V)                                   \
+  V(0, space_size, kSpaceSizeIndex)                                           \
+  V(1, space_used_size, kSpaceUsedSizeIndex)                                  \
+  V(2, space_available_size, kSpaceAvailableSizeIndex)                        \
+  V(3, physical_space_size, kPhysicalSpaceSizeIndex)
+
+#define V(a, b, c) +1
+static const size_t kHeapSpaceStatisticsPropertiesCount =
+    HEAP_SPACE_STATISTICS_PROPERTIES(V);
+#undef V
+
+// Will be populated in InitializeV8Bindings.
+static size_t number_of_heap_spaces = 0;
+
+
 void UpdateHeapStatisticsArrayBuffer(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   HeapStatistics s;
@@ -45,6 +63,23 @@ void UpdateHeapStatisticsArrayBuffer(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+void UpdateHeapSpaceStatisticsBuffer(const FunctionCallbackInfo<Value>& args) {
+  Environment* env = Environment::GetCurrent(args);
+  HeapSpaceStatistics s;
+  Isolate* const isolate = env->isolate();
+  uint32_t* buffer = env->heap_space_statistics_buffer();
+
+  for (size_t i = 0; i < number_of_heap_spaces; i++) {
+    isolate->GetHeapSpaceStatistics(&s, i);
+    size_t const property_offset = i * kHeapSpaceStatisticsPropertiesCount;
+#define V(index, name, _) buffer[property_offset + index] = \
+                              static_cast<uint32_t>(s.name());
+      HEAP_SPACE_STATISTICS_PROPERTIES(V)
+#undef V
+  }
+}
+
+
 void SetFlagsFromString(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
 
@@ -62,10 +97,10 @@ void InitializeV8Bindings(Local<Object> target,
                           Local<Value> unused,
                           Local<Context> context) {
   Environment* env = Environment::GetCurrent(context);
+
   env->SetMethod(target,
                  "updateHeapStatisticsArrayBuffer",
                  UpdateHeapStatisticsArrayBuffer);
-  env->SetMethod(target, "setFlagsFromString", SetFlagsFromString);
 
   env->set_heap_statistics_buffer(new uint32_t[kHeapStatisticsPropertiesCount]);
 
@@ -84,6 +119,56 @@ void InitializeV8Bindings(Local<Object> target,
 
   HEAP_STATISTICS_PROPERTIES(V)
 #undef V
+
+  target->Set(FIXED_ONE_BYTE_STRING(env->isolate(),
+                                    "kHeapSpaceStatisticsPropertiesCount"),
+              Uint32::NewFromUnsigned(env->isolate(),
+                                      kHeapSpaceStatisticsPropertiesCount));
+
+  number_of_heap_spaces = env->isolate()->NumberOfHeapSpaces();
+
+  // Heap space names are extracted once and exposed to JavaScript to
+  // avoid excessive creation of heap space name Strings.
+  HeapSpaceStatistics s;
+  const Local<Array> heap_spaces = Array::New(env->isolate(),
+                                              number_of_heap_spaces);
+  for (size_t i = 0; i < number_of_heap_spaces; i++) {
+    env->isolate()->GetHeapSpaceStatistics(&s, i);
+    Local<String> heap_space_name = String::NewFromUtf8(env->isolate(),
+                                                        s.space_name(),
+                                                        NewStringType::kNormal)
+                                        .ToLocalChecked();
+    heap_spaces->Set(i, heap_space_name);
+  }
+  target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), "kHeapSpaces"),
+              heap_spaces);
+
+  env->SetMethod(target,
+                 "updateHeapSpaceStatisticsArrayBuffer",
+                 UpdateHeapSpaceStatisticsBuffer);
+
+  env->set_heap_space_statistics_buffer(
+    new uint32_t[kHeapSpaceStatisticsPropertiesCount * number_of_heap_spaces]);
+
+  const size_t heap_space_statistics_buffer_byte_length =
+      sizeof(*env->heap_space_statistics_buffer()) *
+      kHeapSpaceStatisticsPropertiesCount *
+      number_of_heap_spaces;
+
+  target->Set(FIXED_ONE_BYTE_STRING(env->isolate(),
+                                    "heapSpaceStatisticsArrayBuffer"),
+              ArrayBuffer::New(env->isolate(),
+                               env->heap_space_statistics_buffer(),
+                               heap_space_statistics_buffer_byte_length));
+
+#define V(i, _, name)                                                         \
+  target->Set(FIXED_ONE_BYTE_STRING(env->isolate(), #name),                   \
+              Uint32::NewFromUnsigned(env->isolate(), i));
+
+  HEAP_SPACE_STATISTICS_PROPERTIES(V)
+#undef V
+
+  env->SetMethod(target, "setFlagsFromString", SetFlagsFromString);
 }
 
 }  // namespace node