stream: make readable & writable computed

This makes readable and writable automatically computed based
on the stream state.

Effectivly deprecating/discouraging manual management of this.

Makes the properties  more consistent and easier to reason about.

Fixes: https://github.com/nodejs/node/issues/29377

PR-URL: https://github.com/nodejs/node/pull/31197
Refs: https://github.com/nodejs/node/issues/29377
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

1 files changed, 15 insertions, 4 deletions

diff --git a/lib/_stream_readable.js b/lib/_stream_readable.js
index 6fa3540057..4c64fd1b4f 100644
--- a/lib/_stream_readable.js
+++ b/lib/_stream_readable.js
@@ -23,6 +23,7 @@
 
 const {
   ArrayIsArray,
+  Boolean,
   NumberIsInteger,
   NumberIsNaN,
   ObjectDefineProperties,
@@ -181,9 +182,6 @@ function Readable(options) {
 
   this._readableState = new ReadableState(options, this, isDuplex);
 
-  // legacy
-  this.readable = true;
-
   if (options) {
     if (typeof options.read === 'function')
       this._read = options.read;
@@ -1057,6 +1055,20 @@ Readable.prototype[SymbolAsyncIterator] = function() {
 // because otherwise some prototype manipulation in
 // userland will fail
 ObjectDefineProperties(Readable.prototype, {
+  readable: {
+    get() {
+      const r = this._readableState;
+      if (!r) return false;
+      if (r.readable !== undefined) return r.readable && !r.endEmitted;
+      return Boolean(!r.destroyed && !r.errorEmitted && !r.endEmitted);
+    },
+    set(val) {
+      // Backwards compat.
+      if (this._readableState) {
+        this._readableState.readable = !!val;
+      }
+    }
+  },
 
   readableHighWaterMark: {
     enumerable: false,
@@ -1198,7 +1210,6 @@ function endReadableNT(state, stream) {
   // Check that we didn't get one last unshift.
   if (!state.errorEmitted && !state.endEmitted && state.length === 0) {
     state.endEmitted = true;
-    stream.readable = false;
     stream.emit('end');
 
     if (state.autoDestroy) {