tswatch/ts/tswatch.classes.watcher.ts

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import * as plugins from './tswatch.plugins';
import { logger } from './tswatch.logging';
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export type TCommandFunction = () => Promise<void>;
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export interface IWatcherConstructorOptions {
filePathToWatch: string;
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commandToExecute: string | TCommandFunction;
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timeout?: number;
}
/**
* A watcher keeps track of one child execution
*/
export class Watcher {
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/**
* used to execute shell commands
*/
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private smartshellInstance = new plugins.smartshell.Smartshell({
executor: 'bash'
});
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/**
* used to execute
*/
private executionTask: plugins.taskbuffer.Task = new plugins.taskbuffer.Task({
name: 'watcherCommandFunctionTask',
taskFunction: async () => {
if (typeof this.options.commandToExecute === 'string') {
throw new Error('cannot execute string as task');
}
await this.options.commandToExecute();
},
buffered: true,
bufferMax: 1
});
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private currentExecution: plugins.smartshell.IExecResultStreaming;
private smartchokWatcher = new plugins.smartchok.Smartchok([], {});
private options: IWatcherConstructorOptions;
constructor(optionsArg: IWatcherConstructorOptions) {
this.options = optionsArg;
}
/**
* start the file
*/
public async start() {
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await this.setupCleanup();
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console.log(`Looking at ${this.options.filePathToWatch} for changes`);
this.smartchokWatcher.add([this.options.filePathToWatch]); // __dirname refers to the directory of this very file
await this.smartchokWatcher.start();
const changeObservable = await this.smartchokWatcher.getObservableFor('change');
changeObservable.subscribe(() => {
this.updateCurrentExecution();
});
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await this.updateCurrentExecution();
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}
/**
* updates the current execution
*/
private async updateCurrentExecution() {
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if (typeof this.options.commandToExecute === 'string') {
if (this.currentExecution) {
logger.log('ok', `reexecuting ${this.options.commandToExecute}`);
process.kill(-this.currentExecution.childProcess.pid);
} else {
logger.log('ok', `executing ${this.options.commandToExecute} for the first time`);
}
this.currentExecution = await this.smartshellInstance.execStreaming(
this.options.commandToExecute
);
this.currentExecution = null;
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} else {
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await this.executionTask.trigger();
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}
}
/**
* this method sets up a clean exit strategy
*/
private async setupCleanup() {
const cleanup = () => {
if (this.currentExecution) {
process.kill(-this.currentExecution.childProcess.pid);
}
};
process.on('exit', () => {
console.log('');
console.log('now exiting!');
cleanup();
process.exit(0);
});
process.on('SIGINT', () => {
console.log('');
console.log('ok! got SIGINT We are exiting! Just cleaning up to exit neatly :)');
cleanup();
process.exit(0);
});
// handle timeout
if (this.options.timeout) {
plugins.smartdelay.delayFor(this.options.timeout).then(() => {
console.log(`timed out afer ${this.options.timeout} milliseconds! exiting!`);
cleanup();
process.exit(0);
});
}
}
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/**
* stops the watcher
*/
public async stop() {
await this.smartchokWatcher.stop();
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if (this.currentExecution && !this.currentExecution.childProcess.killed) {
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process.kill(-this.currentExecution.childProcess.pid);
}
}
}