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/*
** Copyright (C) 2001-2025 Zabbix SIA
**
** This program is free software: you can redistribute it and/or modify it under the terms of
** the GNU Affero General Public License as published by the Free Software Foundation, version 3.
**
** This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
** without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
** See the GNU Affero General Public License for more details.
**
** You should have received a copy of the GNU Affero General Public License along with this program.
** If not, see <https://www.gnu.org/licenses/>.
**/
class CEventHub {
static EVENT = '_EVENT';
static EVENT_NATIVE = 'native';
static EVENT_SUBSCRIBE = 'subscribe';
static EVENT_UNSUBSCRIBE = 'unsubscribe';
#subscribers = new Map();
#latest_data = new Map();
publish({data, descriptor}) {
descriptor = {
[CEventHub.EVENT]: CEventHub.EVENT_NATIVE,
...descriptor
};
descriptor = Object.keys(descriptor).sort().reduce(
(descriptor_sorted, key) => {
descriptor_sorted[key] = descriptor[key];
return descriptor_sorted;
},
{}
);
const descriptor_hash = JSON.stringify(descriptor);
this.#latest_data.delete(descriptor_hash);
this.#latest_data.set(descriptor_hash, {data, descriptor});
for (const {require, callback} of this.#subscribers.values()) {
if (CEventHub.#match(require, descriptor)) {
callback({data, descriptor});
}
}
return this;
}
subscribe({require = {}, callback}) {
require = {[CEventHub.EVENT]: CEventHub.EVENT_NATIVE, ...require};
for (const {data, descriptor} of [...this.#latest_data.values()].reverse()) {
if (CEventHub.#match(require, descriptor)) {
callback({data, descriptor});
break;
}
}
const subscription = {};
this.#subscribers.set(subscription, {require, callback});
this
.publish({
data: require,
descriptor: {...require, [CEventHub.EVENT]: CEventHub.EVENT_SUBSCRIBE}
})
.invalidateData({[CEventHub.EVENT]: CEventHub.EVENT_SUBSCRIBE});
return subscription;
}
unsubscribe(subscription) {
if (!this.#subscribers.has(subscription)) {
return false;
}
const {require} = this.#subscribers.get(subscription);
this.#subscribers.delete(subscription);
this
.publish({
data: require,
descriptor: {...require, [CEventHub.EVENT]: CEventHub.EVENT_UNSUBSCRIBE}
})
.invalidateData({[CEventHub.EVENT]: CEventHub.EVENT_UNSUBSCRIBE});
return true;
}
hasSubscribers(require = {}) {
require = {[CEventHub.EVENT]: CEventHub.EVENT_NATIVE, ...require};
for (const subscriber of this.#subscribers.values()) {
if (CEventHub.#match(require, subscriber.require)) {
return true;
}
}
return false;
}
getData(require) {
for (const {data, descriptor} of [...this.#latest_data.values()].reverse()) {
if (CEventHub.#match(require, descriptor)) {
return data;
}
}
return undefined;
}
invalidateData(require) {
for (const [descriptor_hash, {descriptor}] of this.#latest_data.entries()) {
if (CEventHub.#match(require, descriptor)) {
this.#latest_data.delete(descriptor_hash);
}
}
return this;
}
static #match(require, descriptor) {
for (const [key, value] of Object.entries(require)) {
if (!(key in descriptor) || descriptor[key] !== value) {
return false;
}
}
return true;
}
}
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