stream: implement finished() for ReadableStream and WritableStream

lib/internal/streams/end-of-stream.js

@@ -22,20 +22,23 @@ const {
   validateBoolean
 } = require('internal/validators');
 
-const { Promise } = primordials;
+const { Promise, PromisePrototypeThen } = primordials;
 
 const {
   isClosed,
   isReadable,
   isReadableNodeStream,
+  isReadableStream,
   isReadableFinished,
   isReadableErrored,
   isWritable,
   isWritableNodeStream,
+  isWritableStream,
   isWritableFinished,
   isWritableErrored,
   isNodeStream,
   willEmitClose: _willEmitClose,
+  kIsClosedPromise,
 } = require('internal/streams/utils');
 
 function isRequest(stream) {
@@ -58,14 +61,17 @@ function eos(stream, options, callback) {
 
   callback = once(callback);
 
-  const readable = options.readable ?? isReadableNodeStream(stream);
-  const writable = options.writable ?? isWritableNodeStream(stream);
+  if (isReadableStream(stream) || isWritableStream(stream)) {
+    return eosWeb(stream, options, callback);
+  }
 
   if (!isNodeStream(stream)) {
-    // TODO: Webstreams.
-    throw new ERR_INVALID_ARG_TYPE('stream', 'Stream', stream);
+    throw new ERR_INVALID_ARG_TYPE('stream', ['ReadableStream', 'WritableStream', 'Stream'], stream);
   }
 
+  const readable = options.readable ?? isReadableNodeStream(stream);
+  const writable = options.writable ?? isWritableNodeStream(stream);
+
   const wState = stream._writableState;
   const rState = stream._readableState;
 
@@ -255,6 +261,15 @@ function eos(stream, options, callback) {
   return cleanup;
 }
 
+function eosWeb(stream, opts, callback) {
+  PromisePrototypeThen(
+    stream[kIsClosedPromise].promise,
+    () => process.nextTick(() => callback.call(stream)),
+    (err) => process.nextTick(() => callback.call(stream, err)),
+  );
+  return nop;
+}
+
 function finished(stream, opts) {
   let autoCleanup = false;
   if (opts === null) {

lib/internal/streams/utils.js

@@ -4,13 +4,16 @@ const {
   Symbol,
   SymbolAsyncIterator,
   SymbolIterator,
+  SymbolFor,
 } = primordials;
 
 const kDestroyed = Symbol('kDestroyed');
 const kIsErrored = Symbol('kIsErrored');
 const kIsReadable = Symbol('kIsReadable');
 const kIsDisturbed = Symbol('kIsDisturbed');
 
+const kIsClosedPromise = SymbolFor('nodejs.webstream.isClosedPromise');
+
 function isReadableNodeStream(obj, strict = false) {
   return !!(
     obj &&
@@ -55,6 +58,25 @@ function isNodeStream(obj) {
   );
 }
 
+function isReadableStream(obj) {
+  return !!(
+    obj &&
+    !isNodeStream(obj) &&
+    typeof obj.pipeThrough === 'function' &&
+    typeof obj.getReader === 'function' &&
+    typeof obj.cancel === 'function'
+  );
+}
+
+function isWritableStream(obj) {
+  return !!(
+    obj &&
+    !isNodeStream(obj) &&
+    typeof obj.getWriter === 'function' &&
+    typeof obj.abort === 'function'
+  );
+}
+
 function isIterable(obj, isAsync) {
   if (obj == null) return false;
   if (isAsync === true) return typeof obj[SymbolAsyncIterator] === 'function';
@@ -269,18 +291,21 @@ module.exports = {
   kIsErrored,
   isReadable,
   kIsReadable,
+  kIsClosedPromise,
   isClosed,
   isDestroyed,
   isDuplexNodeStream,
   isFinished,
   isIterable,
   isReadableNodeStream,
+  isReadableStream,
   isReadableEnded,
   isReadableFinished,
   isReadableErrored,
   isNodeStream,
   isWritable,
   isWritableNodeStream,
+  isWritableStream,
   isWritableEnded,
   isWritableFinished,
   isWritableErrored,

lib/internal/webstreams/readablestream.js

@@ -84,6 +84,7 @@ const {
   kIsDisturbed,
   kIsErrored,
   kIsReadable,
+  kIsClosedPromise,
 } = require('internal/streams/utils');
 
 const {
@@ -231,9 +232,11 @@ class ReadableStream {
         port1: undefined,
         port2: undefined,
         promise: undefined,
-      }
+      },
     };
 
+    this[kIsClosedPromise] = createDeferredPromise();
+
     // The spec requires handling of the strategy first
     // here. Specifically, if getting the size and
     // highWaterMark from the strategy fail, that has
@@ -625,8 +628,9 @@ function TransferredReadableStream() {
           writable: undefined,
           port: undefined,
           promise: undefined,
-        }
+        },
       };
+      this[kIsClosedPromise] = createDeferredPromise();
     },
     [], ReadableStream));
 }
@@ -1195,8 +1199,9 @@ function createTeeReadableStream(start, pull, cancel) {
           writable: undefined,
           port: undefined,
           promise: undefined,
-        }
+        },
       };
+      this[kIsClosedPromise] = createDeferredPromise();
       setupReadableStreamDefaultControllerFromSource(
         this,
         ObjectCreate(null, {
@@ -1869,6 +1874,7 @@ function readableStreamCancel(stream, reason) {
 function readableStreamClose(stream) {
   assert(stream[kState].state === 'readable');
   stream[kState].state = 'closed';
+  stream[kIsClosedPromise].resolve();
 
   const {
     reader,
@@ -1890,6 +1896,8 @@ function readableStreamError(stream, error) {
   assert(stream[kState].state === 'readable');
   stream[kState].state = 'errored';
   stream[kState].storedError = error;
+  stream[kIsClosedPromise].reject(error);
+  setPromiseHandled(stream[kIsClosedPromise].promise);
 
   const {
     reader

lib/internal/webstreams/writablestream.js

@@ -67,6 +67,10 @@ const {
   kState,
 } = require('internal/webstreams/util');
 
+const {
+  kIsClosedPromise,
+} = require('internal/streams/utils');
+
 const {
   AbortController,
 } = require('internal/abort_controller');
@@ -175,9 +179,11 @@ class WritableStream {
         port1: undefined,
         port2: undefined,
         promise: undefined,
-      }
+      },
     };
 
+    this[kIsClosedPromise] = createDeferredPromise();
+
     const size = extractSizeAlgorithm(strategy?.size);
     const highWaterMark = extractHighWaterMark(strategy?.highWaterMark, 1);
 
@@ -347,6 +353,7 @@ function TransferredWritableStream() {
           readable: undefined,
         },
       };
+      this[kIsClosedPromise] = createDeferredPromise();
     },
     [], WritableStream));
 }
@@ -726,6 +733,10 @@ function writableStreamRejectCloseAndClosedPromiseIfNeeded(stream) {
       resolve: undefined,
     };
   }
+
+  stream[kIsClosedPromise].reject(stream[kState]?.storedError);
+  setPromiseHandled(stream[kIsClosedPromise].promise);
+
   const {
     writer,
   } = stream[kState];
@@ -839,6 +850,7 @@ function writableStreamFinishInFlightClose(stream) {
   stream[kState].state = 'closed';
   if (stream[kState].writer !== undefined)
     stream[kState].writer[kState].close.resolve?.();
+  stream[kIsClosedPromise].resolve?.();
   assert(stream[kState].pendingAbortRequest.abort.promise === undefined);
   assert(stream[kState].storedError === undefined);
 }