worker: use engine-provided deleter for SharedArrayBuffers

src/sharedarraybuffer_metadata.cc

@@ -89,8 +89,7 @@ SharedArrayBufferMetadata::ForSharedArrayBuffer(
  }
 
  SharedArrayBuffer::Contents contents = source->Externalize();
- SharedArrayBufferMetadataReference r(new SharedArrayBufferMetadata(
- contents.Data(), contents.ByteLength()));
+ SharedArrayBufferMetadataReference r(new SharedArrayBufferMetadata(contents));
  if (r->AssignToSharedArrayBuffer(env, context, source).IsNothing())
  return nullptr;
  return r;
@@ -111,17 +110,22 @@ Maybe<bool> SharedArrayBufferMetadata::AssignToSharedArrayBuffer(
  obj);
 }
 
-SharedArrayBufferMetadata::SharedArrayBufferMetadata(void* data, size_t size)
- : data(data), size(size) { }
+SharedArrayBufferMetadata::SharedArrayBufferMetadata(
+ const SharedArrayBuffer::Contents& contents)
+ : contents_(contents) { }
 
 SharedArrayBufferMetadata::~SharedArrayBufferMetadata() {
- free(data);
+ contents_.Deleter()(contents_.Data(),
+ contents_.ByteLength(),
+ contents_.DeleterData());
 }
 
 MaybeLocal<SharedArrayBuffer> SharedArrayBufferMetadata::GetSharedArrayBuffer(
  Environment* env, Local<Context> context) {
  Local<SharedArrayBuffer> obj =
- SharedArrayBuffer::New(env->isolate(), data, size);
+ SharedArrayBuffer::New(env->isolate(),
+ contents_.Data(),
+ contents_.ByteLength());
 
  if (AssignToSharedArrayBuffer(env, context, obj).IsNothing())
  return MaybeLocal<SharedArrayBuffer>();

src/sharedarraybuffer_metadata.h

@@ -46,16 +46,15 @@ class SharedArrayBufferMetadata
  SharedArrayBufferMetadata(const SharedArrayBufferMetadata&) = delete;
 
  private:
- explicit SharedArrayBufferMetadata(void* data, size_t size);
+ explicit SharedArrayBufferMetadata(const v8::SharedArrayBuffer::Contents&);
 
  // Attach a lifetime tracker object with a reference count to `target`.
  v8::Maybe<bool> AssignToSharedArrayBuffer(
  Environment* env,
  v8::Local<v8::Context> context,
  v8::Local<v8::SharedArrayBuffer> target);
 
- void* data = nullptr;
- size_t size = 0;
+ v8::SharedArrayBuffer::Contents contents_;
 };
 
 } // namespace worker

test/fixtures/wasm-threads-shared-memory.wat

@@ -0,0 +1,4 @@
+(module
+ (memory $mem 1 2 shared)
+ (export "memory" (memory $mem))
+)

test/parallel/test-worker-message-port-wasm-threads.js

@@ -0,0 +1,46 @@
+// Flags: --experimental-worker --experimental-wasm-threads
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { MessageChannel, Worker } = require('worker_threads');
+
+// Test that SharedArrayBuffer instances created from WASM are transferrable
+// through MessageChannels (without crashing).
+
+const fixtures = require('../common/fixtures');
+const wasmSource = fixtures.readSync('wasm-threads-shared-memory.wasm');
+const wasmModule = new WebAssembly.Module(wasmSource);
+const instance = new WebAssembly.Instance(wasmModule);
+
+const { buffer } = instance.exports.memory;
+assert(buffer instanceof SharedArrayBuffer);
+
+{
+ const { port1, port2 } = new MessageChannel();
+ port1.postMessage(buffer);
+ port2.once('message', common.mustCall((buffer2) => {
+ // Make sure serialized + deserialized buffer refer to the same memory.
+ const expected = 'Hello, world!';
+ const bytes = Buffer.from(buffer).write(expected);
+ const deserialized = Buffer.from(buffer2).toString('utf8', 0, bytes);
+ assert.deepStrictEqual(deserialized, expected);
+ }));
+}
+
+{
+ // Make sure we can free WASM memory originating from a thread that already
+ // stopped when we exit.
+ const worker = new Worker(`
+ const { parentPort } = require('worker_threads');
+ const wasmSource = new Uint8Array([${wasmSource.join(',')}]);
+ const wasmModule = new WebAssembly.Module(wasmSource);
+ const instance = new WebAssembly.Instance(wasmModule);
+ parentPort.postMessage(instance.exports.memory);
+ `, { eval: true });
+ worker.once('message', common.mustCall(({ buffer }) => {
+ assert(buffer instanceof SharedArrayBuffer);
+ worker.buf = buffer; // Basically just keep the reference to buffer alive.
+ }));
+ worker.once('exit', common.mustCall());
+ worker.postMessage({ wasmModule });
+}