src: replace heap_utils.createHeapSnapshot with v8.getHeapSnapshot

Remove the internal testing utility and use the public API instead.

PR-URL: #26671
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: joyeecheung

lib/internal/test/heap.js

@@ -179,7 +179,6 @@
       'lib/internal/repl/utils.js',
       'lib/internal/socket_list.js',
       'lib/internal/test/binding.js',
-      'lib/internal/test/heap.js',
       'lib/internal/timers.js',
       'lib/internal/tls.js',
       'lib/internal/trace_events_async_hooks.js',

node.gyp

@@ -200,40 +200,6 @@ void BuildEmbedderGraph(const FunctionCallbackInfo<Value>& args) {
     args.GetReturnValue().Set(ret);
 }
 
-
-class BufferOutputStream : public v8::OutputStream {
- public:
-  BufferOutputStream() : buffer_(new JSString()) {}
-
-  void EndOfStream() override {}
-  int GetChunkSize() override { return 1024 * 1024; }
-  WriteResult WriteAsciiChunk(char* data, int size) override {
-    buffer_->Append(data, size);
-    return kContinue;
-  }
-
-  Local<String> ToString(Isolate* isolate) {
-    return String::NewExternalOneByte(isolate,
-                                      buffer_.release()).ToLocalChecked();
-  }
-
- private:
-  class JSString : public String::ExternalOneByteStringResource {
-   public:
-    void Append(char* data, size_t count) {
-      store_.append(data, count);
-    }
-
-    const char* data() const override { return store_.data(); }
-    size_t length() const override { return store_.size(); }
-
-   private:
-    std::string store_;
-  };
-
-  std::unique_ptr<JSString> buffer_;
-};
-
 namespace {
 class FileOutputStream : public v8::OutputStream {
  public:
@@ -370,17 +336,6 @@ inline bool WriteSnapshot(Isolate* isolate, const char* filename) {
 
 }  // namespace
 
-void CreateHeapSnapshot(const FunctionCallbackInfo<Value>& args) {
-  Isolate* isolate = args.GetIsolate();
-  BufferOutputStream out;
-  TakeSnapshot(isolate, &out);
-  Local<Value> ret;
-  if (JSON::Parse(isolate->GetCurrentContext(),
-                  out.ToString(isolate)).ToLocal(&ret)) {
-    args.GetReturnValue().Set(ret);
-  }
-}
-
 void CreateHeapSnapshotStream(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   HandleScope scope(env->isolate());
@@ -430,9 +385,6 @@ void Initialize(Local<Object> target,
   env->SetMethodNoSideEffect(target,
                              "buildEmbedderGraph",
                              BuildEmbedderGraph);
-  env->SetMethodNoSideEffect(target,
-                             "createHeapSnapshot",
-                             CreateHeapSnapshot);
   env->SetMethodNoSideEffect(target,
                              "triggerHeapSnapshot",
                              TriggerHeapSnapshot);

src/heap_utils.cc

@@ -3,14 +3,88 @@
 const assert = require('assert');
 const util = require('util');
 
-let internalTestHeap;
+let internalBinding;
 try {
-  internalTestHeap = require('internal/test/heap');
+  internalBinding = require('internal/test/binding').internalBinding;
 } catch (e) {
   console.log('using `test/common/heap.js` requires `--expose-internals`');
   throw e;
 }
-const { createJSHeapSnapshot, buildEmbedderGraph } = internalTestHeap;
+
+const { buildEmbedderGraph } = internalBinding('heap_utils');
+const { getHeapSnapshot } = require('v8');
+
+function createJSHeapSnapshot() {
+  const stream = getHeapSnapshot();
+  stream.pause();
+  const dump = JSON.parse(stream.read());
+  const meta = dump.snapshot.meta;
+
+  const nodes =
+    readHeapInfo(dump.nodes, meta.node_fields, meta.node_types, dump.strings);
+  const edges =
+    readHeapInfo(dump.edges, meta.edge_fields, meta.edge_types, dump.strings);
+
+  for (const node of nodes) {
+    node.incomingEdges = [];
+    node.outgoingEdges = [];
+  }
+
+  let fromNodeIndex = 0;
+  let edgeIndex = 0;
+  for (const { type, name_or_index, to_node } of edges) {
+    while (edgeIndex === nodes[fromNodeIndex].edge_count) {
+      edgeIndex = 0;
+      fromNodeIndex++;
+    }
+    const toNode = nodes[to_node / meta.node_fields.length];
+    const fromNode = nodes[fromNodeIndex];
+    const edge = {
+      type,
+      to: toNode,
+      from: fromNode,
+      name: typeof name_or_index === 'string' ? name_or_index : null
+    };
+    toNode.incomingEdges.push(edge);
+    fromNode.outgoingEdges.push(edge);
+    edgeIndex++;
+  }
+
+  for (const node of nodes) {
+    assert.strictEqual(node.edge_count, node.outgoingEdges.length,
+                       `${node.edge_count} !== ${node.outgoingEdges.length}`);
+  }
+  return nodes;
+}
+
+function readHeapInfo(raw, fields, types, strings) {
+  const items = [];
+
+  for (let i = 0; i < raw.length; i += fields.length) {
+    const item = {};
+    for (let j = 0; j < fields.length; j++) {
+      const name = fields[j];
+      let type = types[j];
+      if (Array.isArray(type)) {
+        item[name] = type[raw[i + j]];
+      } else if (name === 'name_or_index') {  // type === 'string_or_number'
+        if (item.type === 'element' || item.type === 'hidden')
+          type = 'number';
+        else
+          type = 'string';
+      }
+
+      if (type === 'string') {
+        item[name] = strings[raw[i + j]];
+      } else if (type === 'number' || type === 'node') {
+        item[name] = raw[i + j];
+      }
+    }
+    items.push(item);
+  }
+
+  return items;
+}
 
 function inspectNode(snapshot) {
   return util.inspect(snapshot, { depth: 4 });