net: allow reading data into a static buffer

Co-Authored-By: Anna Henningsen <anna@addaleax.net>

PR-URL: https://github.com/nodejs/node/pull/25436
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 26 insertions, 5 deletions

diff --git a/lib/internal/stream_base_commons.js b/lib/internal/stream_base_commons.js
index 88896083f19..eb2e53963d8 100644
--- a/lib/internal/stream_base_commons.js
+++ b/lib/internal/stream_base_commons.js
@@ -23,6 +23,7 @@ const {
   setUnrefTimeout,
   getTimerDuration
 } = require('internal/timers');
+const { isUint8Array } = require('internal/util/types');
 const { clearTimeout } = require('timers');
 
 const kMaybeDestroy = Symbol('kMaybeDestroy');
@@ -32,6 +33,9 @@ const kHandle = Symbol('kHandle');
 const kSession = Symbol('kSession');
 
 const debug = require('internal/util/debuglog').debuglog('stream');
+const kBuffer = Symbol('kBuffer');
+const kBufferGen = Symbol('kBufferGen');
+const kBufferCb = Symbol('kBufferCb');
 
 function handleWriteReq(req, data, encoding) {
   const { handle } = req;
@@ -161,9 +165,23 @@ function onStreamRead(arrayBuffer) {
   stream[kUpdateTimer]();
 
   if (nread > 0 && !stream.destroyed) {
-    const offset = streamBaseState[kArrayBufferOffset];
-    const buf = new FastBuffer(arrayBuffer, offset, nread);
-    if (!stream.push(buf)) {
+    let ret;
+    let result;
+    const userBuf = stream[kBuffer];
+    if (userBuf) {
+      result = (stream[kBufferCb](nread, userBuf) !== false);
+      const bufGen = stream[kBufferGen];
+      if (bufGen !== null) {
+        const nextBuf = bufGen();
+        if (isUint8Array(nextBuf))
+          stream[kBuffer] = ret = nextBuf;
+      }
+    } else {
+      const offset = streamBaseState[kArrayBufferOffset];
+      const buf = new FastBuffer(arrayBuffer, offset, nread);
+      result = stream.push(buf);
+    }
+    if (!result) {
       handle.reading = false;
       if (!stream.destroyed) {
         const err = handle.readStop();
@@ -172,7 +190,7 @@ function onStreamRead(arrayBuffer) {
       }
     }
 
-    return;
+    return ret;
   }
 
   if (nread === 0) {
@@ -241,5 +259,8 @@ module.exports = {
   kUpdateTimer,
   kHandle,
   kSession,
-  setStreamTimeout
+  setStreamTimeout,
+  kBuffer,
+  kBufferCb,
+  kBufferGen
 };