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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 | 50x 50x 50x 50x 8x 8x 8x 8x 8x 8x 8x 8x 8x 15x 15x 15x 15x 20x 20x 6x 5x 15x 6x 7x 7x 7x 7x 7x 9x 3x 4x | import { Cardano } from '@cardano-sdk/core';
import { EpochModel } from '../../StakePool';
import { EpochMonitor } from './types';
import { Pool, QueryResult } from 'pg';
import { findLastEpoch } from './queries';
export const EPOCH_POLL_INTERVAL_DEFAULT = 10_000;
/** Class to handle epoch rollover through db polling */
export class DbSyncEpochPollService implements EpochMonitor {
#timeoutId?: ReturnType<typeof setInterval>;
#callbacks: Function[];
#currentEpoch: Promise<Cardano.EpochNo | null>;
/** Db connection */
#db: Pool;
/** Polling interval in ms */
#interval: number;
/**
* @param db Db connection
* @param interval Polling interval in ms
*/
constructor(db: Pool, interval: number) {
this.#db = db;
this.#callbacks = [];
this.#interval = interval;
this.#currentEpoch = Promise.resolve(null);
}
/**
* Poll execution to detect a new epoch rollover
* Upon the occurrence of rollover event it executes all callbacks by registered dependant services
*/
async #executePoll() {
const lastEpoch = await this.#queryLastEpoch();
const currentEpoch = await this.#currentEpoch;
const shouldClearCache = !!(currentEpoch && lastEpoch > currentEpoch);
if (shouldClearCache) this.onEpoch(lastEpoch);
}
/**
* Query the last epoch number stored in db
*
* @returns {number} epoch number
*/
async #queryLastEpoch() {
const result: QueryResult<EpochModel> = await this.#db.query({
name: 'current_epoch',
text: findLastEpoch
});
return Cardano.EpochNo(result.rowCount ? result.rows[0].no : 0);
}
/** Starts the poll execution */
#start() {
if (this.#timeoutId) return;
this.#currentEpoch = this.#queryLastEpoch();
this.#timeoutId = setInterval(() => this.#executePoll(), this.#interval);
}
/** Shutdown the poll execution */
#shutdown() {
if (this.#timeoutId) clearInterval(this.#timeoutId);
}
/** Epoch Rollover event - subscription-based mechanism to manage starting and stopping of epoch poll service */
onEpochRollover(cb: Function) {
this.#callbacks.push(cb);
if (this.#callbacks.length === 1) this.#start();
return () => {
this.#callbacks.splice(this.#callbacks.indexOf(cb), 1);
if (this.#callbacks.length === 0) this.#shutdown();
};
}
/** Get last known epoch */
getLastKnownEpoch() {
return this.#currentEpoch;
}
onEpoch(currentEpoch: Cardano.EpochNo) {
this.#currentEpoch = Promise.resolve(currentEpoch);
for (const cb of this.#callbacks) cb();
}
}
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