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'use strict';
const common = require('../common');
const stream = require('stream');
const assert = require('assert');
const awaitDrainStates = [
1, // after first chunk before callback
1, // after second chunk before callback
0 // resolving chunk pushed after first chunk, awaitDrain is decreased
];
// A writable stream which pushes data onto the stream which pipes into it,
// but only the first time it's written to. Since it's not paused at this time,
// a second write will occur. If the pipe increases awaitDrain twice, we'll
// never get subsequent chunks because 'drain' is only emitted once.
const writable = new stream.Writable({
write: common.mustCall(function(chunk, encoding, cb) {
if (chunk.length === 32 * 1024) { // first chunk
const beforePush = readable._readableState.awaitDrain;
readable.push(Buffer.alloc(34 * 1024)); // above hwm
// We should check if awaitDrain counter is increased.
const afterPush = readable._readableState.awaitDrain;
assert.strictEqual(afterPush - beforePush, 1,
'Counter is not increased for awaitDrain');
}
assert.strictEqual(
awaitDrainStates.shift(),
readable._readableState.awaitDrain,
'State variable awaitDrain is not correct.'
);
cb();
}, 3)
});
// A readable stream which produces two buffers.
const bufs = [Buffer.alloc(32 * 1024), Buffer.alloc(33 * 1024)]; // above hwm
const readable = new stream.Readable({
read: function() {
while (bufs.length > 0) {
this.push(bufs.shift());
}
}
});
readable.pipe(writable);
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