react-native-firebase/lib/modules/database/transaction.js

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/**
* @flow
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* Database Transaction representation wrapper
*/
import { getAppEventName, SharedEventEmitter } from '../../utils/events';
import { getLogger } from '../../utils/log';
import { getNativeModule } from '../../utils/native';
import type Database from './';
let transactionId = 0;
/**
* Uses the push id generator to create a transaction id
* @returns {number}
* @private
*/
const generateTransactionId = (): number => {
return transactionId++;
};
/**
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* @class TransactionHandler
*/
export default class TransactionHandler {
_database: Database;
_transactionListener: Function;
_transactions: { [number]: Object }
constructor(database: Database) {
this._transactions = {};
this._database = database;
this._transactionListener = SharedEventEmitter.addListener(
getAppEventName(this._database, 'database_transaction_event'),
this._handleTransactionEvent.bind(this),
);
}
/**
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* Add a new transaction and start it natively.
* @param reference
* @param transactionUpdater
* @param onComplete
* @param applyLocally
*/
add(reference: Object, transactionUpdater: Function, onComplete?: Function, applyLocally?: boolean = false) {
const id = generateTransactionId();
this._transactions[id] = {
id,
reference,
transactionUpdater,
onComplete,
applyLocally,
completed: false,
started: true,
};
getNativeModule(this._database).transactionStart(reference.path, id, applyLocally);
}
/**
* INTERNALS
*/
/**
*
* @param event
* @returns {*}
* @private
*/
_handleTransactionEvent(event: Object = {}) {
switch (event.type) {
case 'update':
return this._handleUpdate(event);
case 'error':
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return this._handleError(event);
case 'complete':
return this._handleComplete(event);
default:
getLogger(this._database).warn(`Unknown transaction event type: '${event.type}'`, event);
return undefined;
}
}
/**
*
* @param event
* @private
*/
_handleUpdate(event: Object = {}) {
let newValue;
const { id, value } = event;
try {
const transaction = this._transactions[id];
if (!transaction) return;
newValue = transaction.transactionUpdater(value);
} finally {
let abort = false;
if (newValue === undefined) {
abort = true;
}
getNativeModule(this._database).transactionTryCommit(id, { value: newValue, abort });
}
}
/**
*
* @param event
* @private
*/
_handleError(event: Object = {}) {
const transaction = this._transactions[event.id];
if (transaction && !transaction.completed) {
transaction.completed = true;
try {
transaction.onComplete(event.error, false, null);
} finally {
setImmediate(() => {
delete this._transactions[event.id];
});
}
}
}
/**
*
* @param event
* @private
*/
_handleComplete(event: Object = {}) {
const transaction = this._transactions[event.id];
if (transaction && !transaction.completed) {
transaction.completed = true;
try {
transaction.onComplete(null, event.committed, Object.assign({}, event.snapshot));
} finally {
setImmediate(() => {
delete this._transactions[event.id];
});
}
}
}
}