@thermopylae/lib.cache/dist/caches/policy-based.js

Modular cache.

import { EventEmitter } from 'events';
import { NOT_FOUND_VALUE } from "../constants.js";
class PolicyBasedCache extends EventEmitter {
    backend;
    policies;
    constructor(backend, policies) {
        super();
        this.backend = backend;
        this.policies = policies || [];
        for (const policy of this.policies) {
            policy.setDeleter(this.internalDelete);
        }
    }
    get size() {
        return this.backend.size;
    }
    get(key) {
        const entry = this.backend.get(key);
        if (entry === NOT_FOUND_VALUE) {
            for (const policy of this.policies) {
                policy.onMiss(key);
            }
            return entry;
        }
        for (const policy of this.policies) {
            if (policy.onHit(entry) === 0 ) {
                return NOT_FOUND_VALUE;
            }
        }
        return entry.value;
    }
    has(key) {
        return this.backend.has(key);
    }
    set(key, value, argsBundle) {
        let entry = this.backend.get(key);
        if (entry === NOT_FOUND_VALUE) {
            entry = this.backend.set(key, value);
            let policyIndex = 0;
            try {
                for (; policyIndex < this.policies.length; policyIndex++) {
                    this.policies[policyIndex].onSet(entry, argsBundle);
                }
                this.emit("insert" , key, value);
                return;
            }
            catch (e) {
                for (let i = 0; i < policyIndex; i++) {
                    this.policies[i].onDelete(entry); 
                }
                this.backend.del(entry);
                throw e;
            }
        }
        entry.value = value;
        for (const policy of this.policies) {
            policy.onUpdate(entry, argsBundle);
        }
        this.emit("update" , key, value);
    }
    del(key) {
        const entry = this.backend.get(key);
        if (!entry) {
            return false;
        }
        this.internalDelete(entry);
        return true;
    }
    keys() {
        return Array.from(this.backend.keys());
    }
    clear() {
        for (const policy of this.policies) {
            policy.onClear();
        }
        this.backend.clear();
        this.emit("flush" );
    }
    on(event, listener) {
        return super.on(event, listener);
    }
    internalDelete = (entry) => {
        for (const policy of this.policies) {
            policy.onDelete(entry);
        }
        this.emit("delete" , entry.key, entry.value);
        this.backend.del(entry);
    };
}
export { PolicyBasedCache };