深入研究React中setState源码(3)

var _prodInvariant = require('./reactProdInvariant');
var invariant = require('fbjs/lib/invariant');
var OBSERVED_ERROR = {};
var TransactionImpl = {
 reinitializeTransaction: function () {
  //getTransactionWrappers这个函数ReactDefaultBatchingStrategy.js中声明的，上面有；返回一个数组；
  this.transactionWrappers = this.getTransactionWrappers();
  if (this.wrapperInitData) {
   this.wrapperInitData.length = 0;
  } else {
   this.wrapperInitData = [];
  }
  this._isInTransaction = false;
 },

 _isInTransaction: false,
 getTransactionWrappers: null,
 isInTransaction: function () {
  return !!this._isInTransaction;
 },
 perform: function (method, scope, a, b, c, d, e, f) {
  var errorThrown;
  var ret;
  try {
   this._isInTransaction = true;
   errorThrown = true;
   //var TRANSACTION_WRAPPERS = [FLUSH_BATCHED_UPDATES, RESET_BATCHED_UPDATES];
   //1 这里会先执行所有的TRANSACTION_WRAPPERS中成员的initialize方法，上面声明的其都是emptyFunction
   this.initializeAll(0);
   //2 这里其实还是执行的 enqueueUpdate 函数
   ret = method.call(scope, a, b, c, d, e, f);
   errorThrown = false;
  } finally {
   try {
    if (errorThrown) {
     // If `method` throws, prefer to show that stack trace over any thrown
     // by invoking `closeAll`.
     try {
      this.closeAll(0);
     } catch (err) {}
    } else {
     // Since `method` didn't throw, we don't want to silence the exception
     // here.
     //3 执行TRANSACTION_WRAPPERS对象中成员的所有close方法；
     this.closeAll(0);
    }
   } finally {
    this._isInTransaction = false;
   }
  }
  return ret;
 },

 initializeAll: function (startIndex) {
  var transactionWrappers = this.transactionWrappers;
  for (var i = startIndex; i < transactionWrappers.length; i++) {
   var wrapper = transactionWrappers[i];
   try {
    
    this.wrapperInitData[i] = OBSERVED_ERROR;
    this.wrapperInitData[i] = wrapper.initialize ? wrapper.initialize.call(this) : null;
   } finally {
    if (this.wrapperInitData[i] === OBSERVED_ERROR) {
     
     try {
      this.initializeAll(i + 1);
     } catch (err) {}
    }
   }
  }
 },
 closeAll: function (startIndex) {
  var transactionWrappers = this.transactionWrappers;
  for (var i = startIndex; i < transactionWrappers.length; i++) {
   var wrapper = transactionWrappers[i];
   var initData = this.wrapperInitData[i];
   var errorThrown;
   try {
  
    errorThrown = true;
    if (initData !== OBSERVED_ERROR && wrapper.close) {
     wrapper.close.call(this, initData);
    }
    errorThrown = false;
   } finally {
    if (errorThrown) {
    
     try {
      this.closeAll(i + 1);
     } catch (e) {}
    }
   }
  }
  this.wrapperInitData.length = 0;
 }
};

module.exports = TransactionImpl

//3 执行TRANSACTION_WRAPPERS对象中成员的所有close方法；
var FLUSH_BATCHED_UPDATES = {
 initialize: emptyFunction,
 close: ReactUpdates.flushBatchedUpdates.bind(ReactUpdates)
};