Allow releasing the lock in the middle of close/error steps

index.bs

@@ -2586,9 +2586,10 @@ the {{ReadableStream}}'s public API.
  1. Perform ! [$ReadableStreamClose$](|stream|).
  1. Let |reader| be |stream|.[=ReadableStream/[[reader]]=].
  1. If |reader| is not undefined and |reader| [=implements=] {{ReadableStreamBYOBReader}},
-  1. [=list/For each=] |readIntoRequest| of |reader|.[=ReadableStreamBYOBReader/[[readIntoRequests]]=],
-   1. Perform |readIntoRequest|'s [=read-into request/close steps=], given undefined.
+  1. Let |readIntoRequests| be |reader|.[=ReadableStreamBYOBReader/[[readIntoRequests]]=].
   1. Set |reader|.[=ReadableStreamBYOBReader/[[readIntoRequests]]=] to an empty [=list=].
+  1. [=list/For each=] |readIntoRequest| of |readIntoRequests|,
+   1. Perform |readIntoRequest|'s [=read-into request/close steps=], given undefined.
  1. Let |sourceCancelPromise| be !
     |stream|.[=ReadableStream/[[controller]]=].[$ReadableStreamController/[[CancelSteps]]$](|reason|).
  1. Return the result of [=reacting=] to |sourceCancelPromise| with a fulfillment step that returns
@@ -2605,9 +2606,10 @@ the {{ReadableStream}}'s public API.
  1. If |reader| is undefined, return.
  1. [=Resolve=] |reader|.[=ReadableStreamGenericReader/[[closedPromise]]=] with undefined.
  1. If |reader| [=implements=] {{ReadableStreamDefaultReader}},
-  1. [=list/For each=] |readRequest| of |reader|.[=ReadableStreamDefaultReader/[[readRequests]]=],
-   1. Perform |readRequest|'s [=read request/close steps=].
+  1. Let |readRequests| be |reader|.[=ReadableStreamDefaultReader/[[readRequests]]=].
   1. Set |reader|.[=ReadableStreamDefaultReader/[[readRequests]]=] to an empty [=list=].
+  1. [=list/For each=] |readRequest| of |readRequests|,
+   1. Perform |readRequest|'s [=read request/close steps=].
 </div>
 
 <div algorithm>
@@ -2622,15 +2624,16 @@ the {{ReadableStream}}'s public API.
  1. [=Reject=] |reader|.[=ReadableStreamGenericReader/[[closedPromise]]=] with |e|.
  1. Set |reader|.[=ReadableStreamGenericReader/[[closedPromise]]=].\[[PromiseIsHandled]] to true.
  1. If |reader| [=implements=] {{ReadableStreamDefaultReader}},
-  1. [=list/For each=] |readRequest| of |reader|.[=ReadableStreamDefaultReader/[[readRequests]]=],
-    1. Perform |readRequest|'s [=read request/error steps=], given |e|.
+  1. Let |readRequests| be |reader|.[=ReadableStreamDefaultReader/[[readRequests]]=].
   1. Set |reader|.[=ReadableStreamDefaultReader/[[readRequests]]=] to a new empty [=list=].
+  1. [=list/For each=] |readRequest| of |readRequests|,
+    1. Perform |readRequest|'s [=read request/error steps=], given |e|.
  1. Otherwise,
    1. Assert: |reader| [=implements=] {{ReadableStreamBYOBReader}}.
-   1. [=list/For each=] |readIntoRequest| of
-      |reader|.[=ReadableStreamBYOBReader/[[readIntoRequests]]=],
-    1. Perform |readIntoRequest|'s [=read-into request/error steps=], given |e|.
+   1. Let |readIntoRequests| be |reader|.[=ReadableStreamBYOBReader/[[readIntoRequests]]=].
    1. Set |reader|.[=ReadableStreamBYOBReader/[[readIntoRequests]]=] to a new empty [=list=].
+   1. [=list/For each=] |readIntoRequest| of |readIntoRequests|,
+    1. Perform |readIntoRequest|'s [=read-into request/error steps=], given |e|.
 </div>
 
 <div algorithm>

reference-implementation/lib/abstract-ops/readable-streams.js

@@ -745,10 +745,11 @@ function ReadableStreamCancel(stream, reason) {
 
   const reader = stream._reader;
   if (reader !== undefined && ReadableStreamBYOBReader.isImpl(reader)) {
-    for (const readIntoRequest of reader._readIntoRequests) {
+    const readIntoRequests = reader._readIntoRequests;
+    reader._readIntoRequests = [];
+    for (const readIntoRequest of readIntoRequests) {
       readIntoRequest.closeSteps(undefined);
     }
-    reader._readIntoRequests = [];
   }
 
   const sourceCancelPromise = stream._controller[CancelSteps](reason);
@@ -769,10 +770,11 @@ function ReadableStreamClose(stream) {
   resolvePromise(reader._closedPromise, undefined);
 
   if (ReadableStreamDefaultReader.isImpl(reader)) {
-    for (const readRequest of reader._readRequests) {
+    const readRequests = reader._readRequests;
+    reader._readRequests = [];
+    for (const readRequest of readRequests) {
       readRequest.closeSteps();
     }
-    reader._readRequests = [];
   }
 }
 
@@ -792,19 +794,19 @@ function ReadableStreamError(stream, e) {
   setPromiseIsHandledToTrue(reader._closedPromise);
 
   if (ReadableStreamDefaultReader.isImpl(reader)) {
-    for (const readRequest of reader._readRequests) {
+    const readRequests = reader._readRequests;
+    reader._readRequests = [];
+    for (const readRequest of readRequests) {
       readRequest.errorSteps(e);
     }
-
-    reader._readRequests = [];
   } else {
     assert(ReadableStreamBYOBReader.isImpl(reader));
 
-    for (const readIntoRequest of reader._readIntoRequests) {
+    const readIntoRequests = reader._readIntoRequests;
+    reader._readIntoRequests = [];
+    for (const readIntoRequest of readIntoRequests) {
       readIntoRequest.errorSteps(e);
     }
-
-    reader._readIntoRequests = [];
   }
 }