mirror of
https://github.com/facebook/react.git
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Paul O’Shannessy
253 lines
9.3 KiB
JavaScript
253 lines
9.3 KiB
JavaScript
/**
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* Copyright 2013 Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* @providesModule Transaction
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*/
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"use strict";
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var throwIf = require('throwIf');
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var DUAL_TRANSACTION = 'DUAL_TRANSACTION';
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var MISSING_TRANSACTION = 'MISSING_TRANSACTION';
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if (__DEV__) {
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DUAL_TRANSACTION =
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'Cannot initialize transaction when there is already an outstanding ' +
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'transaction. Common causes of this are trying to render a component ' +
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'when you are already rendering a component or attempting a state ' +
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'transition while in a render function. Another possibility is that ' +
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'you are rendering new content (or state transitioning) in a ' +
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'componentDidRender callback. If this is not the case, please report the ' +
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'issue immediately.';
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MISSING_TRANSACTION =
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'Cannot close transaction when there is none open.';
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}
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/**
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* `Transaction` creates a black box that is able to wrap any method such that
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* certain invariants are maintained before and after the method is invoked
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* (Even if an exception is thrown while invoking the wrapped method). Whoever
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* instantiates a transaction can provide enforcers of the invariants at
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* creation time. The `Transaction` class itself will supply one additional
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* automatic invariant for you - the invariant that any transaction instance
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* should not be ran while it is already being ran. You would typically create a
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* single instance of a `Transaction` for reuse multiple times, that potentially
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* is used to wrap several different methods. Wrappers are extremely simple -
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* they only require implementing two methods.
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*
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* <pre>
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* wrappers (injected at creation time)
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* + +
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* | |
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* +-----------------|--------|--------------+
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* | v | |
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* | +---------------+ | |
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* | +--| wrapper1 |---|----+ |
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* | | +---------------+ v | |
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* | | +-------------+ | |
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* | | +----| wrapper2 |--------+ |
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* | | | +-------------+ | | |
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* | | | | | |
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* | v v v v | wrapper
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* | +---+ +---+ +---------+ +---+ +---+ | invariants
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* perform(anyMethod) | | | | | | | | | | | | maintained
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* +----------------->|-|---|-|---|-->|anyMethod|---|---|-|---|-|-------->
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* | | | | | | | | | | | |
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* | | | | | | | | | | | |
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* | | | | | | | | | | | |
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* | +---+ +---+ +---------+ +---+ +---+ |
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* | initialize close |
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* +-----------------------------------------+
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* </pre>
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*
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* Bonus:
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* - Reports timing metrics by method name and wrapper index.
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*
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* Use cases:
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* - Preserving the input selection ranges before/after reconciliation.
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* Restoring selection even in the event of an unexpected error.
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* - Deactivating events while rearranging the DOM, preventing blurs/focuses,
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* while guaranteeing that afterwards, the event system is reactivated.
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* - Flushing a queue of collected DOM mutations to the main UI thread after a
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* reconciliation takes place in a worker thread.
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* - Invoking any collected `componentDidRender` callbacks after rendering new
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* content.
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* - (Future use case): Wrapping particular flushes of the `ReactWorker` queue
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* to preserve the `scrollTop` (an automatic scroll aware DOM).
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* - (Future use case): Layout calculations before and after DOM upates.
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*
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* Transactional plugin API:
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* - A module that has an `initialize` method that returns any precomputation.
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* - and a `close` method that accepts the precomputation. `close` is invoked
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* when the wrapped process is completed, or has failed.
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*
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* @param {Array<TransactionalWrapper>} transactionWrapper Wrapper modules
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* that implement `initialize` and `close`.
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* @return {Transaction} Single transaction for reuse in thread.
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*
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* @class Transaction
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*/
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var Mixin = {
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/**
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* Sets up this instance so that it is prepared for collecting metrics. Does
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* so such that this setup method may be used on an instance that is already
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* initialized, in a way that does not consume additional memory upon reuse.
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* That can be useful if you decide to make your subclass of this mixin a
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* "PooledClass".
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*/
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reinitializeTransaction: function() {
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this.transactionWrappers = this.getTransactionWrappers();
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if (!this.wrapperInitData) {
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this.wrapperInitData = [];
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} else {
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this.wrapperInitData.length = 0;
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}
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if (!this.timingMetrics) {
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this.timingMetrics = {};
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}
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this.timingMetrics.methodInvocationTime = 0;
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if (!this.timingMetrics.wrapperInitTimes) {
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this.timingMetrics.wrapperInitTimes = [];
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} else {
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this.timingMetrics.wrapperInitTimes.length = 0;
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}
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if (!this.timingMetrics.wrapperCloseTimes) {
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this.timingMetrics.wrapperCloseTimes = [];
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} else {
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this.timingMetrics.wrapperCloseTimes.length = 0;
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}
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this._isInTransaction = false;
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},
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_isInTransaction: false,
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/**
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* @abstract
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* @return {Array<TransactionWrapper>} Array of transaction wrappers.
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*/
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getTransactionWrappers: null,
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isInTransaction: function() {
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return !!this._isInTransaction;
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},
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/**
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* Executes the function within a safety window. Use this for the top level
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* methods that result in large amounts of computation/mutations that would
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* need to be safety checked.
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*
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* @param {function} method Member of scope to call.
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* @param {Object} scope Scope to invoke from.
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* @param {Object?=} args... Arguments to pass to the method (optional).
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* Helps prevent need to bind in many cases.
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* @returns Return value from `method`.
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*/
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perform: function(method, scope, a, b, c, d, e, f) {
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throwIf(this.isInTransaction(), DUAL_TRANSACTION);
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var memberStart = Date.now();
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var err = null;
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var ret;
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try {
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this.initializeAll();
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ret = method.call(scope, a, b, c, d, e, f);
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} catch (ie_requires_catch) {
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err = ie_requires_catch;
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} finally {
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var memberEnd = Date.now();
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this.methodInvocationTime += (memberEnd - memberStart);
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try {
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this.closeAll();
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} catch (closeAllErr) {
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err = err || closeAllErr;
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}
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}
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if (err) {
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throw err;
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}
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return ret;
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},
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initializeAll: function() {
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this._isInTransaction = true;
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var transactionWrappers = this.transactionWrappers;
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var wrapperInitTimes = this.timingMetrics.wrapperInitTimes;
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var err = null;
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for (var i = 0; i < transactionWrappers.length; i++) {
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var initStart = Date.now();
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var wrapper = transactionWrappers[i];
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try {
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this.wrapperInitData[i] =
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wrapper.initialize ? wrapper.initialize.call(this) : null;
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} catch (initErr) {
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err = err || initErr; // Remember the first error.
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this.wrapperInitData[i] = Transaction.OBSERVED_ERROR;
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} finally {
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var curInitTime = wrapperInitTimes[i];
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var initEnd = Date.now();
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wrapperInitTimes[i] = (curInitTime || 0) + (initEnd - initStart);
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}
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}
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if (err) {
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throw err;
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}
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},
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/**
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* Invokes each of `this.transactionWrappers.close[i]` functions, passing into
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* them the respective return values of `this.transactionWrappers.init[i]`
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* (`close`rs that correspond to initializers that failed will not be
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* invoked).
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*/
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closeAll: function() {
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throwIf(!this.isInTransaction(), MISSING_TRANSACTION);
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var transactionWrappers = this.transactionWrappers;
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var wrapperCloseTimes = this.timingMetrics.wrapperCloseTimes;
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var err = null;
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for (var i = 0; i < transactionWrappers.length; i++) {
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var wrapper = transactionWrappers[i];
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var closeStart = Date.now();
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var initData = this.wrapperInitData[i];
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try {
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if (initData !== Transaction.OBSERVED_ERROR) {
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wrapper.close && wrapper.close.call(this, initData);
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}
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} catch (closeErr) {
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err = err || closeErr; // Remember the first error.
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} finally {
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var closeEnd = Date.now();
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var curCloseTime = wrapperCloseTimes[i];
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wrapperCloseTimes[i] = (curCloseTime || 0) + (closeEnd - closeStart);
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}
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}
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this.wrapperInitData.length = 0;
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this._isInTransaction = false;
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if (err) {
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throw err;
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}
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}
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};
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var Transaction = {
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Mixin: Mixin,
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/**
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* Token to look for to determine if an error occured.
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*/
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OBSERVED_ERROR: {}
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};
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module.exports = Transaction;
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