101 lines
2.5 KiB
JavaScript
101 lines
2.5 KiB
JavaScript
// Copyright 2015-2017 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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import EventEmitter from 'eventemitter3';
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const defaults = {
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from: 0,
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to: 'latest',
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interval: 5000,
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filter: () => true
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};
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const subscribeToEvents = (contract, events, opt = {}) => {
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const { api } = contract;
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opt = Object.assign({}, defaults, opt);
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let filter = null;
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let interval = null;
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const unsubscribe = () => {
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if (filter) {
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filter
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.then((filterId) => {
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return api.eth.uninstallFilter(filterId);
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})
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.catch((err) => {
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emitter.emit('error', err);
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});
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filter = null;
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}
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if (interval) {
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clearInterval(interval);
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interval = null;
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}
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};
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const emitter = new EventEmitter();
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emitter.unsubscribe = unsubscribe;
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const fetcher = (method, filterId) => () => {
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api
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.eth[method](filterId)
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.then((logs) => {
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logs = contract.parseEventLogs(logs);
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for (let log of logs) {
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if (opt.filter(log)) {
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emitter.emit('log', log);
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emitter.emit(log.event, log);
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}
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}
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})
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.catch((err) => {
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emitter.emit('error', err);
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});
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};
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const signatures = events
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.filter((event) => contract.instance[event])
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.map((event) => contract.instance[event].signature);
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filter = api.eth
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.newFilter({
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fromBlock: opt.from, toBlock: opt.to,
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address: contract.address,
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topics: [signatures]
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})
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.then((filterId) => {
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fetcher('getFilterLogs', filterId)(); // fetch immediately
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const fetchChanges = fetcher('getFilterChanges', filterId);
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interval = setInterval(fetchChanges, opt.interval);
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return filterId;
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})
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.catch((err) => {
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emitter.emit('error', err);
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throw err; // reject Promise
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});
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return emitter;
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};
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export default subscribeToEvents;
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