76 lines
2.3 KiB
JavaScript
76 lines
2.3 KiB
JavaScript
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'use strict';
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const common = require('../common');
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const stream = require('stream');
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const assert = require('assert');
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// A consumer stream with a very low highWaterMark, which starts in a state
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// where it buffers the chunk it receives rather than indicating that they
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// have been consumed.
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const writable = new stream.Writable({
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highWaterMark: 5
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});
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let isCurrentlyBufferingWrites = true;
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const queue = [];
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writable._write = (chunk, encoding, cb) => {
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if (isCurrentlyBufferingWrites)
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queue.push({ chunk, cb });
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else
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cb();
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};
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const readable = new stream.Readable({
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read() {}
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});
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readable.pipe(writable);
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readable.once('pause', common.mustCall(() => {
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assert.strictEqual(
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readable._readableState.awaitDrainWriters,
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writable,
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'Expected awaitDrainWriters to be a Writable but instead got ' +
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`${readable._readableState.awaitDrainWriters}`
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);
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// First pause, resume manually. The next write() to writable will still
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// return false, because chunks are still being buffered, so it will increase
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// the awaitDrain counter again.
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process.nextTick(common.mustCall(() => {
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readable.resume();
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}));
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readable.once('pause', common.mustCall(() => {
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assert.strictEqual(
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readable._readableState.awaitDrainWriters,
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writable,
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'.resume() should not reset the awaitDrainWriters, but instead got ' +
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`${readable._readableState.awaitDrainWriters}`
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);
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// Second pause, handle all chunks from now on. Once all callbacks that
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// are currently queued up are handled, the awaitDrain drain counter should
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// fall back to 0 and all chunks that are pending on the readable side
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// should be flushed.
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isCurrentlyBufferingWrites = false;
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for (const queued of queue)
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queued.cb();
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}));
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}));
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readable.push(Buffer.alloc(100)); // Fill the writable HWM, first 'pause'.
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readable.push(Buffer.alloc(100)); // Second 'pause'.
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readable.push(Buffer.alloc(100)); // Should get through to the writable.
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readable.push(null);
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writable.on('finish', common.mustCall(() => {
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assert.strictEqual(
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readable._readableState.awaitDrainWriters,
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null,
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`awaitDrainWriters should be reset to null
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after all chunks are written but instead got
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${readable._readableState.awaitDrainWriters}`
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);
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// Everything okay, all chunks were written.
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}));
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