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stream: refactor clearBuffer and writableState #45682

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stream: refactor clearBuffer and writableState #45682

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f686b69
stream: refactor clearBuffer
anonrig Nov 29, 2022
3409df7
stream: remove isDuplex check on writable state
anonrig Nov 29, 2022
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20 changes: 7 additions & 13 deletions lib/internal/streams/writable.js
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Original file line number Diff line number Diff line change
Expand Up @@ -75,14 +75,6 @@ function nop() {}
const kOnFinished = Symbol('kOnFinished');

function WritableState(options, stream, isDuplex) {
// Duplex streams are both readable and writable, but share
// the same options object.
// However, some cases require setting options to different
// values for the readable and the writable sides of the duplex stream,
// e.g. options.readableObjectMode vs. options.writableObjectMode, etc.
if (typeof isDuplex !== 'boolean')
isDuplex = stream instanceof Stream.Duplex;

// Object stream flag to indicate whether or not this stream
// contains buffers or objects.
this.objectMode = !!(options && options.objectMode);
Expand Down Expand Up @@ -537,16 +529,18 @@ function clearBuffer(stream, state) {
return;
}

state.bufferProcessing = true;
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I don't understand why this is better?

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Unnecessary length operation was done before state.bufferProcessing assignment is done. This change eliminates that.

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I still don't see it. This is actually slower for the case where bufferedLength is 0... since it unnecessarily sets and unsets bufferProcessing.


const { buffered, bufferedIndex, objectMode } = state;
const bufferedLength = buffered.length - bufferedIndex;

if (!bufferedLength) {
if (bufferedLength === 0) {
state.bufferProcessing = false;
return;
}

let i = bufferedIndex;

state.bufferProcessing = true;
if (bufferedLength > 1 && stream._writev) {
state.pendingcb -= bufferedLength - 1;

Expand All @@ -565,12 +559,12 @@ function clearBuffer(stream, state) {

resetBuffer(state);
} else {
do {
for (; i < buffered.length && !state.writing; i++) {
const { chunk, encoding, callback } = buffered[i];
buffered[i++] = null;
buffered[i] = null;
const len = objectMode ? 1 : chunk.length;
doWrite(stream, state, false, len, chunk, encoding, callback);
} while (i < buffered.length && !state.writing);
}
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This is unnecessary change


if (i === buffered.length) {
resetBuffer(state);
Expand Down