flow like the river

VISUALIZACION/node_modules/parcel-bundler/lib/workerfarm/WorkerFarm.js

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+'use strict';
+
+function _asyncToGenerator(fn) { return function () { var gen = fn.apply(this, arguments); return new Promise(function (resolve, reject) { function step(key, arg) { try { var info = gen[key](arg); var value = info.value; } catch (error) { reject(error); return; } if (info.done) { resolve(value); } else { return Promise.resolve(value).then(function (value) { step("next", value); }, function (err) { step("throw", err); }); } } return step("next"); }); }; }
+
+var _require = require('events');
+
+const EventEmitter = _require.EventEmitter;
+
+const os = require('os');
+const errorUtils = require('./errorUtils');
+const Worker = require('./Worker');
+
+let shared = null;
+class WorkerFarm extends EventEmitter {
+  constructor(options, farmOptions = {}) {
+    super();
+    this.options = Object.assign({
+      maxConcurrentWorkers: WorkerFarm.getNumWorkers(),
+      maxConcurrentCallsPerWorker: 10,
+      forcedKillTime: 100,
+      warmWorkers: true,
+      useLocalWorker: true,
+      workerPath: '../worker'
+    }, farmOptions);
+
+    this.started = false;
+    this.warmWorkers = 0;
+    this.children = new Map();
+    this.callQueue = [];
+
+    this.localWorker = require(this.options.workerPath);
+    this.run = this.mkhandle('run');
+
+    this.init(options);
+  }
+
+  warmupWorker(method, args) {
+    // Workers have started, but are not warmed up yet.
+    // Send the job to a remote worker in the background,
+    // but use the result from the local worker - it will be faster.
+    if (this.started) {
+      let promise = this.addCall(method, [...args, true]);
+      if (promise) {
+        promise.then(() => {
+          this.warmWorkers++;
+          if (this.warmWorkers >= this.children.size) {
+            this.emit('warmedup');
+          }
+        }).catch(() => {});
+      }
+    }
+  }
+
+  mkhandle(method) {
+    return function (...args) {
+      // Child process workers are slow to start (~600ms).
+      // While we're waiting, just run on the main thread.
+      // This significantly speeds up startup time.
+      if (this.shouldUseRemoteWorkers()) {
+        return this.addCall(method, [...args, false]);
+      } else {
+        if (this.options.warmWorkers) {
+          this.warmupWorker(method, args);
+        }
+
+        return this.localWorker[method](...args, false);
+      }
+    }.bind(this);
+  }
+
+  onError(error, childId) {
+    // Handle ipc errors
+    if (error.code === 'ERR_IPC_CHANNEL_CLOSED') {
+      return this.stopChild(childId);
+    }
+  }
+
+  onExit(childId) {
+    // delay this to give any sends a chance to finish
+    setTimeout(() => {
+      let doQueue = false;
+      let child = this.children.get(childId);
+      if (child && child.calls.size) {
+        var _iteratorNormalCompletion = true;
+        var _didIteratorError = false;
+        var _iteratorError = undefined;
+
+        try {
+          for (var _iterator = child.calls.values()[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
+            let call = _step.value;
+
+            call.retries++;
+            this.callQueue.unshift(call);
+            doQueue = true;
+          }
+        } catch (err) {
+          _didIteratorError = true;
+          _iteratorError = err;
+        } finally {
+          try {
+            if (!_iteratorNormalCompletion && _iterator.return) {
+              _iterator.return();
+            }
+          } finally {
+            if (_didIteratorError) {
+              throw _iteratorError;
+            }
+          }
+        }
+      }
+      this.stopChild(childId);
+      if (doQueue) {
+        this.processQueue();
+      }
+    }, 10);
+  }
+
+  startChild() {
+    let worker = new Worker(this.options.workerPath, this.options);
+
+    worker.on('request', data => {
+      this.processRequest(data, worker);
+    });
+
+    worker.on('response', () => {
+      // allow any outstanding calls to be processed
+      this.processQueue();
+    });
+
+    worker.once('exit', () => {
+      this.onExit(worker.id);
+    });
+
+    worker.on('error', err => {
+      this.onError(err, worker.id);
+    });
+
+    this.children.set(worker.id, worker);
+  }
+
+  stopChild(childId) {
+    let child = this.children.get(childId);
+    if (child) {
+      child.stop();
+      this.children.delete(childId);
+    }
+  }
+
+  processQueue() {
+    var _this = this;
+
+    return _asyncToGenerator(function* () {
+      if (_this.ending || !_this.callQueue.length) return;
+
+      if (_this.children.size < _this.options.maxConcurrentWorkers) {
+        _this.startChild();
+      }
+
+      var _iteratorNormalCompletion2 = true;
+      var _didIteratorError2 = false;
+      var _iteratorError2 = undefined;
+
+      try {
+        for (var _iterator2 = _this.children.values()[Symbol.iterator](), _step2; !(_iteratorNormalCompletion2 = (_step2 = _iterator2.next()).done); _iteratorNormalCompletion2 = true) {
+          let child = _step2.value;
+
+          if (!_this.callQueue.length) {
+            break;
+          }
+
+          if (child.calls.size < _this.options.maxConcurrentCallsPerWorker) {
+            child.call(_this.callQueue.shift());
+          }
+        }
+      } catch (err) {
+        _didIteratorError2 = true;
+        _iteratorError2 = err;
+      } finally {
+        try {
+          if (!_iteratorNormalCompletion2 && _iterator2.return) {
+            _iterator2.return();
+          }
+        } finally {
+          if (_didIteratorError2) {
+            throw _iteratorError2;
+          }
+        }
+      }
+    })();
+  }
+
+  processRequest(data, child = false) {
+    return _asyncToGenerator(function* () {
+      let result = {
+        idx: data.idx,
+        type: 'response'
+      };
+
+      let method = data.method;
+      let args = data.args;
+      let location = data.location;
+      let awaitResponse = data.awaitResponse;
+
+      if (!location) {
+        throw new Error('Unknown request');
+      }
+
+      const mod = require(location);
+      try {
+        let func;
+        if (method) {
+          func = mod[method];
+        } else {
+          func = mod;
+        }
+        result.contentType = 'data';
+        result.content = yield func(...args);
+      } catch (e) {
+        result.contentType = 'error';
+        result.content = errorUtils.errorToJson(e);
+      }
+
+      if (awaitResponse) {
+        if (child) {
+          child.send(result);
+        } else {
+          return result;
+        }
+      }
+    })();
+  }
+
+  addCall(method, args) {
+    if (this.ending) return; // don't add anything new to the queue
+
+    return new Promise((resolve, reject) => {
+      this.callQueue.push({
+        method,
+        args: args,
+        retries: 0,
+        resolve,
+        reject
+      });
+      this.processQueue();
+    });
+  }
+
+  end() {
+    var _this2 = this;
+
+    return _asyncToGenerator(function* () {
+      _this2.ending = true;
+      var _iteratorNormalCompletion3 = true;
+      var _didIteratorError3 = false;
+      var _iteratorError3 = undefined;
+
+      try {
+        for (var _iterator3 = _this2.children.keys()[Symbol.iterator](), _step3; !(_iteratorNormalCompletion3 = (_step3 = _iterator3.next()).done); _iteratorNormalCompletion3 = true) {
+          let childId = _step3.value;
+
+          _this2.stopChild(childId);
+        }
+      } catch (err) {
+        _didIteratorError3 = true;
+        _iteratorError3 = err;
+      } finally {
+        try {
+          if (!_iteratorNormalCompletion3 && _iterator3.return) {
+            _iterator3.return();
+          }
+        } finally {
+          if (_didIteratorError3) {
+            throw _iteratorError3;
+          }
+        }
+      }
+
+      _this2.ending = false;
+      shared = null;
+    })();
+  }
+
+  init(options) {
+    this.localWorker.init(options, true);
+    this.initRemoteWorkers(options);
+  }
+
+  initRemoteWorkers(options) {
+    var _this3 = this;
+
+    return _asyncToGenerator(function* () {
+      _this3.started = false;
+      _this3.warmWorkers = 0;
+
+      // Start workers if there isn't enough workers already
+      for (let i = _this3.children.size; i < _this3.options.maxConcurrentWorkers; i++) {
+        _this3.startChild();
+      }
+
+      // Reliable way of initialising workers
+      let promises = [];
+      var _iteratorNormalCompletion4 = true;
+      var _didIteratorError4 = false;
+      var _iteratorError4 = undefined;
+
+      try {
+        for (var _iterator4 = _this3.children.values()[Symbol.iterator](), _step4; !(_iteratorNormalCompletion4 = (_step4 = _iterator4.next()).done); _iteratorNormalCompletion4 = true) {
+          let child = _step4.value;
+
+          promises.push(new Promise(function (resolve, reject) {
+            child.call({
+              method: 'init',
+              args: [options],
+              retries: 0,
+              resolve,
+              reject
+            });
+          }));
+        }
+      } catch (err) {
+        _didIteratorError4 = true;
+        _iteratorError4 = err;
+      } finally {
+        try {
+          if (!_iteratorNormalCompletion4 && _iterator4.return) {
+            _iterator4.return();
+          }
+        } finally {
+          if (_didIteratorError4) {
+            throw _iteratorError4;
+          }
+        }
+      }
+
+      yield Promise.all(promises);
+      if (_this3.options.maxConcurrentWorkers > 0) {
+        _this3.started = true;
+        _this3.emit('started');
+      }
+    })();
+  }
+
+  shouldUseRemoteWorkers() {
+    return !this.options.useLocalWorker || this.started && (this.warmWorkers >= this.children.size || !this.options.warmWorkers);
+  }
+
+  static getShared(options) {
+    if (!shared) {
+      shared = new WorkerFarm(options);
+    } else if (options) {
+      shared.init(options);
+    }
+
+    return shared;
+  }
+
+  static getNumWorkers() {
+    if (process.env.PARCEL_WORKERS) {
+      return parseInt(process.env.PARCEL_WORKERS, 10);
+    }
+
+    let cores;
+    try {
+      cores = require('physical-cpu-count');
+    } catch (err) {
+      cores = os.cpus().length;
+    }
+    return cores || 1;
+  }
+}
+
+module.exports = WorkerFarm;