137 lines
3.2 KiB
JavaScript
137 lines
3.2 KiB
JavaScript
var stream = require("stream"),
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constants = require("./constants"),
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util = require("util");
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var ReadableStreamBuffer = module.exports = function(opts) {
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var that = this;
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stream.Stream.call(this);
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opts = opts || {};
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var frequency = opts.hasOwnProperty("frequency") ? opts.frequency : constants.DEFAULT_FREQUENCY;
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var chunkSize = opts.chunkSize || constants.DEFAULT_CHUNK_SIZE;
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var initialSize = opts.initialSize || constants.DEFAULT_INITIAL_SIZE;
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var incrementAmount = opts.incrementAmount || constants.DEFAULT_INCREMENT_AMOUNT;
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var size = 0;
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var buffer = new Buffer(initialSize);
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var encoding = null;
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this.readable = true;
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this.writable = false;
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var sendData = function() {
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var amount = Math.min(chunkSize, size);
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if (amount > 0) {
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var chunk = null;
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if(encoding) {
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chunk = buffer.toString(encoding, 0, amount);
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}
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else {
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chunk = new Buffer(amount);
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buffer.copy(chunk, 0, 0, amount);
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}
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that.emit("data", chunk);
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if(amount < buffer.length)
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buffer.copy(buffer, 0, amount, size);
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size -= amount;
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}
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if(size === 0 && !that.readable) {
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that.emit("end");
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that.emit("close");
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if (sendData && sendData.interval) {
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clearInterval(sendData.interval);
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sendData.interval = null;
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}
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}
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};
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this.size = function() {
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return size;
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};
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this.maxSize = function() {
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return buffer.length;
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};
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var increaseBufferIfNecessary = function(incomingDataSize) {
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if((buffer.length - size) < incomingDataSize) {
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var factor = Math.ceil((incomingDataSize - (buffer.length - size)) / incrementAmount);
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var newBuffer = new Buffer(buffer.length + (incrementAmount * factor));
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buffer.copy(newBuffer, 0, 0, size);
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buffer = newBuffer;
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}
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};
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this.put = function(data, encoding) {
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if(!that.readable) return;
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var wasEmpty = size === 0;
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if(Buffer.isBuffer(data)) {
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increaseBufferIfNecessary(data.length);
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data.copy(buffer, size, 0);
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size += data.length;
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}
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else {
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data = data + "";
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var dataSizeInBytes = Buffer.byteLength(data);
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increaseBufferIfNecessary(dataSizeInBytes);
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buffer.write(data, size, encoding || "utf8");
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size += dataSizeInBytes;
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}
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if (wasEmpty && size > 0) {
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this.emit('readable')
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}
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if (!this.isPaused && !frequency) {
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while (size > 0) {
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sendData();
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}
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}
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};
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this.pause = function() {
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this.isPaused = true;
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if(sendData && sendData.interval) {
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clearInterval(sendData.interval);
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delete sendData.interval;
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}
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};
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this.resume = function() {
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this.isPaused = false;
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if(sendData && !sendData.interval && frequency > 0) {
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sendData.interval = setInterval(sendData, frequency);
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}
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};
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this.destroy = function() {
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that.emit("end");
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if(sendData.interval) clearInterval(sendData.interval);
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sendData = null;
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that.readable = false;
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that.emit("close");
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};
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this.destroySoon = function() {
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that.readable = false;
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if (!sendData.interval) {
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that.emit("end");
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that.emit("close");
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}
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};
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this.setEncoding = function(_encoding) {
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encoding = _encoding;
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};
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this.resume();
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};
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util.inherits(ReadableStreamBuffer, stream.Stream);
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