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e688fe6b7e
Previously, flushing on zlib streams was implemented through
stream 'drain' handlers. This has a number of downsides; in
particular, it is complex, and could lead to unpredictable
behaviour, since it meant that in a sequence like
```js
compressor.write('abc');
compressor.flush();
waitForMoreDataAsynchronously(() => {
compressor.write('def');
});
```
it was not fully deterministic whether the flush happens after
the second chunk is written or the first one.
This commit replaces this mechanism by one that piggy-backs
along the stream’s write queue, using a “special” `Buffer`
instance that signals that a flush is currently due.
PR-URL: https://github.com/nodejs/node/pull/23186
Reviewed-By: James M Snell <jasnell@gmail.com>
49 lines
926 B
JavaScript
49 lines
926 B
JavaScript
'use strict';
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require('../common');
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const assert = require('assert');
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const zlib = require('zlib');
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const bigData = Buffer.alloc(10240, 'x');
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const opts = {
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level: 0,
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highWaterMark: 16
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};
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const deflater = zlib.createDeflate(opts);
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// shim deflater.flush so we can count times executed
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let flushCount = 0;
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let drainCount = 0;
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const flush = deflater.flush;
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deflater.flush = function(kind, callback) {
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flushCount++;
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flush.call(this, kind, callback);
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};
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deflater.write(bigData);
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const ws = deflater._writableState;
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const beforeFlush = ws.needDrain;
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let afterFlush = ws.needDrain;
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deflater.flush(function(err) {
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afterFlush = ws.needDrain;
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});
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deflater.on('drain', function() {
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drainCount++;
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});
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process.once('exit', function() {
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assert.strictEqual(
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beforeFlush, true);
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assert.strictEqual(
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afterFlush, false);
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assert.strictEqual(
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drainCount, 1);
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assert.strictEqual(
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flushCount, 1);
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});
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