Unified worker

core/lib/common/workers/graphics.ts

@@ -0,0 +1,162 @@
+import { ChildProcess, spawn } from 'child_process';
+import { ensureDir, remove } from 'fs-extra';
+import { fs } from 'mz';
+import { connect } from 'net';
+
+// This class is awrapper around a simple gstreamer pipe to capture a source into individual frames
+export default class ScreenCapture {
+	private proc?: ChildProcess;
+	private exit: {
+		reason?: string;
+		details: {
+			error?: Error;
+			stdout: string;
+			stderr: string;
+			code: number | null;
+		};
+	};
+
+	constructor(
+		public source: { type: string; options?: any },
+		public destination: string,
+	) {
+		this.exit = {
+			details: {
+				stdout: '',
+				stderr: '',
+				code: null,
+			},
+		};
+	}
+
+	public async startCapture(): Promise<void> {
+		await ensureDir(this.destination);
+
+		const gstreamerHandle = () => {
+			this.proc = spawn(
+				'gst-launch-1.0',
+				[
+					`${this.parseSource()} ! jpegenc quality=10 ! multifilesink location="${
+						this.destination
+					}/%06d.jpg"`,
+				],
+				{
+					shell: '/bin/bash',
+				},
+			);
+			this.proc.stdout!.on('data', (data) => {
+				this.exit.details.stdout += `${data.toString('utf-8')}\n`;
+			});
+			this.proc.stderr!.on('data', (data) => {
+				this.exit.details.stderr += `${data.toString('utf-8')}\n`;
+			});
+			this.proc.on('exit', (code) => {
+				this.exit.details.code = code;
+				this.proc = undefined;
+			});
+			this.proc.on('error', (error) => {
+				this.exit.reason = 'Could not start gstreamer pipeline';
+				this.exit.details.error = error;
+				this.proc = undefined;
+			});
+		};
+
+		if (this.source.type === 'rfbsrc') {
+			if (
+				this.source.options.host == null ||
+				this.source.options.port == null
+			) {
+				throw new Error('Missing critical configuration of the VNC server');
+			}
+			// A little retry mechanism
+			const waitForSocket = (tries = 0) => {
+				if (tries > 20) {
+					this.exit.reason = `Timeout: Could not connect to VNC server ${this.source.options.host}:${this.source.options.port}`;
+					return;
+				}
+
+				const handleRetry = () => {
+					setTimeout(waitForSocket, 3000, tries++);
+				};
+
+				const socket = connect(
+					this.source.options.port,
+					this.source.options.host,
+					() => {
+						socket.removeListener('error', handleRetry);
+						gstreamerHandle();
+					},
+				);
+				socket.once('error', handleRetry);
+			};
+			waitForSocket();
+		} else {
+			gstreamerHandle();
+		}
+	}
+
+	public stopCapture(): Promise<void> {
+		return new Promise(async (resolve, reject) => {
+			if (this.proc != null) {
+				const clean = () => {
+					if (timeout != null) {
+						clearTimeout(timeout);
+					}
+					if (interval != null) {
+						clearInterval(interval);
+					}
+					this.proc = undefined;
+				};
+				const exitHandler = () => {
+					clean();
+					resolve();
+				};
+
+				// For an unknown reason the gst process sometimes refuses to die, so let's check
+				// if it has not periodaclly and retry
+				const interval = setInterval(async () => {
+					if (this.proc != null) {
+						const procInfo = (
+							await fs.readFile('/proc/' + this.proc.pid + '/status')
+						).toString();
+
+						if (procInfo.match(/State:\s+[RSDT]/)) {
+							this.proc.kill('SIGINT');
+						} else {
+							this.proc.removeListener('exit', exitHandler);
+							exitHandler();
+						}
+					}
+				}, 2000);
+				const timeout = setTimeout(() => {
+					if (this.proc != null) {
+						this.proc.removeListener('exit', exitHandler);
+					}
+					reject(new Error('Could not stop gstreamer pipeline.'));
+				}, 30000);
+				this.proc.on('exit', exitHandler);
+			} else {
+				reject(new Error(JSON.stringify(this.exit)));
+			}
+		});
+	}
+
+	private parseSource(): string {
+		switch (this.source.type) {
+			case 'rfbsrc':
+				return `${this.source.type} host=${this.source.options.host} port=${this.source.options.port} view-only=true`;
+			case 'v4l2src':
+				// With our catpture HW there is an error when negotiating the resolution, so we crop the extra manually
+				return `${this.source.type} ! decodebin ! videocrop left=90 right=90 bottom=70 top=70`;
+			default:
+				return this.source.options.type;
+		}
+	}
+	public async teardown(): Promise<void> {
+		if (this.proc != null) {
+			this.proc.kill('SIGINT');
+			this.proc = undefined;
+		}
+		await remove(this.destination);
+	}
+}