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less memory leak #9

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less memory leak #9

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73 changes: 23 additions & 50 deletions index.js
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
const { Transform } = require('stream');
const { Transform } = require("stream");

/**
* The ReadlineTransform is reading String or Buffer content from a Readable stream
Expand All @@ -8,64 +8,37 @@ const { Transform } = require('stream');
* @param {Boolean} opts.ignoreEndOfBreak - if content ends with line break, ignore last empty line (default: true)
* @param {Boolean} opts.skipEmpty - if line is empty string, skip it (default: false)
*/
const NEWLINE = 0x0a;
class ReadlineTransform extends Transform {
constructor(options) {
const opts = options || {};
opts.objectMode = true;
super(opts);
this._brRe = opts.breakMatcher || /\r?\n/;
this._ignoreEndOfBreak = 'ignoreEndOfBreak' in opts ? Boolean(opts.ignoreEndOfBreak) : true;
this._skipEmpty = Boolean(opts.skipEmpty);
this._buf = null;
constructor() {
super();
this._buf = Buffer.alloc(1024);
this.wptr = 0;
}

_transform(chunk, encoding, cb) {
let str;
if (Buffer.isBuffer(chunk) || encoding === 'buffer') {
str = chunk.toString('utf8');
} else {
str = chunk;
_transform(chunk, enc, cb) {
let lb;
while ((lb = chunk.indexOf(NEWLINE)) >= 0 && chunk.length) {
this._emitData(chunk.slice(0, lb + 1));
chunk = chunk.slice(lb + 1);
}

try {
if (this._buf !== null) {
this._buf += str;
} else {
this._buf = str;
}

const lines = this._buf.split(this._brRe);
const lastIndex = lines.length - 1;
for (let i = 0; i < lastIndex; i++) {
this._writeItem(lines[i]);
}

const lastLine = lines[lastIndex];
if (lastLine.length) {
this._buf = lastLine;
} else if (!this._ignoreEndOfBreak) {
this._buf = '';
} else {
this._buf = null;
}
cb();
} catch(err) {
cb(err); // invalid data type;
if (chunk.length) {
chunk.copy(this._buf, this.wptr, 0, chunk.length);
this.wptr += chunk.length;
}
cb(null, null);
}

_flush(cb) {
if (this._buf !== null) {
this._writeItem(this._buf);
this._buf = null;
_emitData(slice) {
if (this.wptr) {
this.emit("data", Buffer.concat([this._buf.slice(0, this.wptr), slice]));
this.wptr = 0;
} else {
this.emit("data", slice);
}
cb();
}

_writeItem(line) {
if (line.length > 0 || !this._skipEmpty) {
this.push(line);
}
_flush(cb) {
cb(this._buf.slice(0, this.wptr));
}
}

Expand Down
178 changes: 42 additions & 136 deletions test/index.test.js
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Original file line number Diff line number Diff line change
@@ -1,139 +1,45 @@
const assert = require('assert');
const { PassThrough } = require('stream');
const ReadlineTransform = require('../');
const MemoryWriteStream = require('./memory_write_stream');

describe('ReadlineTransform', () => {

context('data ends without line break', () => {
it('transforms all lines', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform();
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['foo', 'bar', 'baz']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write(Buffer.from('foo\nba'));
readStream.write('r\r');
readStream.end(Buffer.from('\nbaz'));
});

context('data contains empty lines and skipEmpty option is true', () => {
it('transforms with dropping empty lines', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform({ skipEmpty: true });
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['foo', 'bar', 'baz']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write('foo\nba');
readStream.write(Buffer.from('r\r\n\n\r'));
readStream.end(Buffer.from('\nbaz'));
});
})
})

context('data ends with line break', () => {
it('transforms all lines except last empty line', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform();
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['foo', 'bar', '', 'baz']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write(Buffer.from('foo\r\nbar\n'));
readStream.end('\r\nbaz\r\n');
const assert = require("assert");
const { PassThrough } = require("stream");
const ReadlineTransform = require("../");
const MemoryWriteStream = require("./memory_write_stream");

// let describe = (str, cb) => console.log(str) && cb();
// let it = (str, cb) => console.log(str) && cb();

describe("ReadlineTransform", () => {
it("should work", () => {
const { Transform, Stream } = require("stream");
let t = new Stream.PassThrough();
const g = new ReadlineTransform();
const quote = Buffer.from('"');

const inputFormatter = new Transform({
transform: (buf, enc, cb) => {
cb(
null,
Buffer.from('\ninput: "' + buf.toString().replace("\n", "\\n") + '"')
);
},
});

context('ignoreEndOfBreak is false', () => {
it('transforms all lines', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform({ ignoreEndOfBreak: false });
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['foo', 'bar', '', 'baz', '']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write(Buffer.from('foo\r\nbar\n'));
readStream.end('\r\nbaz\r\n');
});
})

context('skipEmpty option is true', () => {
it('transforms with dropping empty lines', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform({ skipEmpty: true });
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['foo', 'bar', 'baz']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write('foo\r\nbar\n');
readStream.end(Buffer.from('\r\nbaz\r\n'));
});
})

context('ignoreEndOfBreak is false and skipEmpty option is true', () => {
it('works with dropping all empty lines', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform({ ignoreEndOfBreak: false, skipEmpty: true });
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['foo', ' ', 'bar']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write(Buffer.from('foo\n \n'));
readStream.write('\n\n');
readStream.write(Buffer.from('bar\n'));
readStream.end();
});
})

})

context('line break is special', () => {
it('transforms with dropping last empty line', (done) => {
const readStream = new PassThrough();
const transform = new ReadlineTransform({ breakMatcher: '_\n' });
const writeStream = new MemoryWriteStream();

writeStream.on('finish', () => {
assert.deepEqual(writeStream.data, ['', 'foo', 'bar', 'baz', '']);
done();
});

readStream.pipe(transform).pipe(writeStream);

readStream.write(Buffer.from('_\nfoo_\nbar_\nbaz_\n_\n'));
readStream.end();
const outputFormatter = new Transform({
transform: (buf, enc, cb) => {
cb(
null,
Buffer.from('\nOutput: "' + buf.toString().replace("\n", "\\n") + '"')
);
},
});
})

})
t.pipe(inputFormatter).pipe(process.stdout);
t.pipe(g).pipe(outputFormatter).pipe(process.stdout);
t.write("line1 hello!\n");
console.log("buf:" + g._buf);
t.write("line2 \n line3 yadayada");
console.log("buf:" + g._buf);

t.write("yada \n line4");
console.log("buf:" + g._buf);
console.log("flushing");
g._flush(console.log);
});
});