Javier Goizueta
c647f852d6
Also fixed bug where sampling query generation needed results of count queries
92 lines
2.8 KiB
JavaScript
92 lines
2.8 KiB
JavaScript
/**
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* PhasedExecution handles the execution of async tasks (via Promises)
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* which have dependencies between them in a simplified manner.
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* Instead of using the complete task dependency graph, tasks
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* are organized into execution phases. So that tasks from a latter
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* phase will be initialized after tasks from previous phases have
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* finished.
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*
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* All tasks place their results in a shared object to make them
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* available to tasks of latter phases.
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*
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* Each phase is defined by a function that defines its tasks.
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*
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* Example:
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*
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* let p = new PhasedExecution();
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* // Define first phase with tasks 1 & 2
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* p.phase(() => {
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* p.results.phase1 = 1
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* p.task(new Promise((resolve) => {
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* setTimeout( () => {
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* console.log('At 1:', p.results);
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* p.results.task1 = 100;
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* resolve();
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* }, 400);
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* }));
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* p.task(new Promise((resolve) => {
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* setTimeout( () => {
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* console.log('At 2:', p.results);
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* p.results.task2 = 200;
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* resolve();
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* }, 100);
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* }));
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* });
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* // Define second phase with tasks 3 & 4
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* p.phase(() => {
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* p.results.phase2 = 2
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* p.task(new Promise((resolve) => {
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* setTimeout( () => {
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* console.log('At 3:', p.results);
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* p.results.task3 = 300;
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* resolve();
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* }, 50);
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* }));
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* p.task(new Promise((resolve) => {
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* setTimeout( () => {
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* console.log('At 4:', p.results);
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* p.results.task4 = 400;
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* resolve();
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* }, 100);
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* }));
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* });
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* // Define third phase with task 5
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* p.phase(() => {
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* p.results.phase3 = 3
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* p.task(new Promise((resolve) => {
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* setTimeout( () => {
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* console.log('At 5:', p.results);
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* p.results.task5 = 500;
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* resolve();
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* }, 50);
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* }));
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* });
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* // Execute all tasks
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* p.run(() => {
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* console.log("RESULTS:", p.results);
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* });
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*/
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module.exports = class PhasedExecution {
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constructor() {
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this.results = {};
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this.phases = [];
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}
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phase(phasegenerator) {
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this.phases.push(phasegenerator);
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}
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task(promise) {
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this.tasks.push(promise);
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}
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run(callback) {
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this.tasks = [];
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let phase = this.phases.shift();
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if (phase) {
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phase(this);
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return Promise.all(this.tasks)
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.then(this.run())
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.then(() => { if (callback) { callback(this.results); } });
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}
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}
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};
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// TODO: error handling
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