160 lines
2.6 KiB
JavaScript
160 lines
2.6 KiB
JavaScript
/*!
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* async.js - async object class for bcoin
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* Copyright (c) 2016-2017, Christopher Jeffrey (MIT License).
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* https://github.com/bcoin-org/bcoin
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*/
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'use strict';
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var util = require('./util');
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var co = require('./co');
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var Lock = require('./lock');
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var assert = require('assert');
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var EventEmitter = require('events').EventEmitter;
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/**
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* An abstract object that handles state and
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* provides recallable open and close methods.
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* @alias module:utils.AsyncObject
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* @constructor
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* @property {Boolean} loading
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* @property {Boolean} closing
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* @property {Boolean} loaded
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*/
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function AsyncObject() {
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assert(this instanceof AsyncObject);
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EventEmitter.call(this);
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this._asyncLock = new Lock();
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this.loading = false;
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this.closing = false;
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this.loaded = false;
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}
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util.inherits(AsyncObject, EventEmitter);
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/**
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* Open the object (recallable).
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* @method
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* @returns {Promise}
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*/
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AsyncObject.prototype.open = co(function* open() {
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var unlock = yield this._asyncLock.lock();
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try {
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return yield this.__open();
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} finally {
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unlock();
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}
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});
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/**
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* Open the object (without a lock).
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* @method
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* @private
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* @returns {Promise}
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*/
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AsyncObject.prototype.__open = co(function* open() {
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if (this.loaded)
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return;
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this.emit('preopen');
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this.loading = true;
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try {
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yield this._open();
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} catch (e) {
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this.loading = false;
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this.emit('error', e);
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throw e;
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}
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this.loading = false;
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this.loaded = true;
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this.emit('open');
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});
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/**
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* Close the object (recallable).
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* @method
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* @returns {Promise}
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*/
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AsyncObject.prototype.close = co(function* close() {
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var unlock = yield this._asyncLock.lock();
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try {
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return yield this.__close();
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} finally {
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unlock();
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}
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});
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/**
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* Close the object (without a lock).
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* @method
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* @private
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* @returns {Promise}
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*/
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AsyncObject.prototype.__close = co(function* close() {
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if (!this.loaded)
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return;
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this.emit('preclose');
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this.closing = true;
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try {
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yield this._close();
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} catch (e) {
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this.closing = false;
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this.emit('error', e);
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throw e;
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}
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this.closing = false;
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this.loaded = false;
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this.emit('close');
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});
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/**
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* Close the object (recallable).
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* @method
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* @returns {Promise}
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*/
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AsyncObject.prototype.destroy = AsyncObject.prototype.close;
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/**
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* Initialize the object.
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* @private
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* @returns {Promise}
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*/
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AsyncObject.prototype._open = function _open(callback) {
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throw new Error('Abstract method.');
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};
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/**
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* Close the object.
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* @private
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* @returns {Promise}
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*/
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AsyncObject.prototype._close = function _close(callback) {
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throw new Error('Abstract method.');
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};
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/*
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* Expose
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*/
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module.exports = AsyncObject;
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