@neo4j/graphql
Version:
A GraphQL to Cypher query execution layer for Neo4j and JavaScript GraphQL implementations
105 lines • 4.46 kB
JavaScript
;
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [http://neo4j.com]
*
* This file is part of Neo4j.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
return c > 3 && r && Object.defineProperty(target, key, r), r;
};
var __importDefault = (this && this.__importDefault) || function (mod) {
return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.Neo4jGraphQLSubscriptionsCDCEngine = void 0;
const cypher_builder_1 = __importDefault(require("@neo4j/cypher-builder"));
const events_1 = require("events");
const typescript_memoize_1 = require("typescript-memoize");
const constants_1 = require("../../constants");
const cdc_api_1 = require("./cdc/cdc-api");
const cdc_event_parser_1 = require("./cdc/cdc-event-parser");
class Neo4jGraphQLSubscriptionsCDCEngine {
constructor({ driver, pollTime = 1000, queryConfig, onlyGraphQLEvents = false, }) {
this.events = new events_1.EventEmitter();
this.closed = false;
this.cdcApi = new cdc_api_1.CDCApi(driver, queryConfig);
this.pollTime = pollTime;
this.onlyGraphQLEvents = onlyGraphQLEvents;
}
// This memoize is done to keep typings correct whilst avoiding the performance ir of the throw
get parser() {
if (!this._parser)
throw new Error("CDC Event parser not available on SubscriptionEngine. Forgot to call .init on SubscriptionEngine?");
return this._parser;
}
async init({ schemaModel }) {
await this.cdcApi.refreshCursor();
this._parser = new cdc_event_parser_1.CDCEventParser(schemaModel);
this.subscribeToLabels = this.getLabelsToFilter(schemaModel);
schemaModel.concreteEntities.map((e) => Array.from(e.labels));
this.triggerPoll();
}
/** Stops CDC polling */
close() {
this.closed = true;
if (this.timer) {
clearTimeout(this.timer);
this.timer = undefined;
}
}
triggerPoll() {
this.timer = setTimeout(() => {
if (this.closed) {
return;
}
this.pollEvents()
.catch((err) => {
console.error(err);
})
.finally(() => {
this.triggerPoll();
});
}, this.pollTime);
}
async pollEvents() {
let txFilter;
if (this.onlyGraphQLEvents) {
const appMetadata = new cypher_builder_1.default.Param(constants_1.APP_ID);
txFilter = new cypher_builder_1.default.Map({
app: appMetadata,
});
}
const cdcEvents = await this.cdcApi.queryEvents(this.subscribeToLabels, txFilter);
for (const cdcEvent of cdcEvents) {
const parsedEvent = this.parser.parseCDCEvent(cdcEvent);
if (parsedEvent) {
this.events.emit(parsedEvent.event, parsedEvent);
}
}
}
getLabelsToFilter(schemaModel) {
const uniqueLabels = new Set(schemaModel.concreteEntities.flatMap((e) => Array.from(e.labels)));
return Array.from(uniqueLabels);
}
}
exports.Neo4jGraphQLSubscriptionsCDCEngine = Neo4jGraphQLSubscriptionsCDCEngine;
__decorate([
(0, typescript_memoize_1.Memoize)()
], Neo4jGraphQLSubscriptionsCDCEngine.prototype, "parser", null);
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