+++ /dev/null
-
-/**
- * Copyright (c) 2019 The xterm.js authors. All rights reserved.
- * @license MIT
- */
-
-declare const setTimeout: (handler: () => void, timeout?: number) => void;
-
-/**
- * Safety watermark to avoid memory exhaustion and browser engine crash on fast data input.
- * Enable flow control to avoid this limit and make sure that your backend correctly
- * propagates this to the underlying pty. (see docs for further instructions)
- * Since this limit is meant as a safety parachute to prevent browser crashs,
- * it is set to a very high number. Typically xterm.js gets unresponsive with
- * a 100 times lower number (>500 kB).
- */
-const DISCARD_WATERMARK = 50000000; // ~50 MB
-
-/**
- * The max number of ms to spend on writes before allowing the renderer to
- * catch up with a 0ms setTimeout. A value of < 33 to keep us close to
- * 30fps, and a value of < 16 to try to run at 60fps. Of course, the real FPS
- * depends on the time it takes for the renderer to draw the frame.
- */
-const WRITE_TIMEOUT_MS = 12;
-
-/**
- * Threshold of max held chunks in the write buffer, that were already processed.
- * This is a tradeoff between extensive write buffer shifts (bad runtime) and high
- * memory consumption by data thats not used anymore.
- */
-const WRITE_BUFFER_LENGTH_THRESHOLD = 50;
-
-export class WriteBuffer {
- private _writeBuffer: (string | Uint8Array)[] = [];
- private _callbacks: ((() => void) | undefined)[] = [];
- private _pendingData = 0;
- private _bufferOffset = 0;
-
- constructor(private _action: (data: string | Uint8Array) => void) { }
-
- public writeSync(data: string | Uint8Array): void {
- // force sync processing on pending data chunks to avoid in-band data scrambling
- // does the same as innerWrite but without event loop
- if (this._writeBuffer.length) {
- for (let i = this._bufferOffset; i < this._writeBuffer.length; ++i) {
- const data = this._writeBuffer[i];
- const cb = this._callbacks[i];
- this._action(data);
- if (cb) cb();
- }
- // reset all to avoid reprocessing of chunks with scheduled innerWrite call
- this._writeBuffer = [];
- this._callbacks = [];
- this._pendingData = 0;
- // stop scheduled innerWrite by offset > length condition
- this._bufferOffset = 0x7FFFFFFF;
- }
- // handle current data chunk
- this._action(data);
- }
-
- public write(data: string | Uint8Array, callback?: () => void): void {
- if (this._pendingData > DISCARD_WATERMARK) {
- throw new Error('write data discarded, use flow control to avoid losing data');
- }
-
- // schedule chunk processing for next event loop run
- if (!this._writeBuffer.length) {
- this._bufferOffset = 0;
- setTimeout(() => this._innerWrite());
- }
-
- this._pendingData += data.length;
- this._writeBuffer.push(data);
- this._callbacks.push(callback);
- }
-
- protected _innerWrite(): void {
- const startTime = Date.now();
- while (this._writeBuffer.length > this._bufferOffset) {
- const data = this._writeBuffer[this._bufferOffset];
- const cb = this._callbacks[this._bufferOffset];
- this._bufferOffset++;
-
- this._action(data);
- this._pendingData -= data.length;
- if (cb) cb();
-
- if (Date.now() - startTime >= WRITE_TIMEOUT_MS) {
- break;
- }
- }
- if (this._writeBuffer.length > this._bufferOffset) {
- // Allow renderer to catch up before processing the next batch
- // trim already processed chunks if we are above threshold
- if (this._bufferOffset > WRITE_BUFFER_LENGTH_THRESHOLD) {
- this._writeBuffer = this._writeBuffer.slice(this._bufferOffset);
- this._callbacks = this._callbacks.slice(this._bufferOffset);
- this._bufferOffset = 0;
- }
- setTimeout(() => this._innerWrite(), 0);
- } else {
- this._writeBuffer = [];
- this._callbacks = [];
- this._pendingData = 0;
- this._bufferOffset = 0;
- }
- }
-}