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import { Store } from '../store/store';
/**
* **SQLite3** {@link Store.Driver}. This class provides a facade derived from
* the built-in {@link Storage} interface to **SQLite3** databases under NodeJS.
* This class implementing the {@link Store.Driver} contract is used as backing
* storage by the {@link StateWorker}, if run in a NodeJS environment.
*
* @see {@link Store.Driver}
*/
export class SQLite3 implements Store.Driver {
/**
* Private **database** used as backing storage to read/write key/value pairs.
*/
private readonly database: Database;
/**
* Returns the number of key/value pairs.
*/
public get length(): Promise<number> {
return new Promise((resolve) => this.database.transaction(() => {
const result = this.database.prepare(`
SELECT COUNT(*) AS count FROM '${this.version}'
`).get() as { count: number };
resolve(result.count);
})());
}
/**
* Public {@link SQLite3} **constructor** consuming the `name` and `version`
* used to construct this instance of a {@link Store.Driver}.
*
* @param name - The `name` to address this instance by.
* @param version - The `version` of this instance.
*/
public constructor(
/**
* The `name` to address this instance by.
*/
public readonly name: string,
/**
* The `version` of this instance.
*/
public readonly version: string
) {
// eslint-disable-next-line @typescript-eslint/no-shadow
const Database = require('better-sqlite3');
const { createHash } = require('crypto');
const { join } = require('path');
process.on('exit', () => this.database.close());
process.on('SIGHUP', () => process.exit(128 + 1));
process.on('SIGINT', () => process.exit(128 + 2));
process.on('SIGTERM', () => process.exit(128 + 15));
const hash = createHash('md5').update(this.name).digest('hex');
this.database = new Database(join(__dirname, hash) + '.sdb').exec(`
CREATE TABLE IF NOT EXISTS '${this.version}' (
key TEXT PRIMARY KEY NOT NULL,
value TEXT
)
`);
}
/**
* Removes all key/value pairs, if there are any.
*
* @returns A {@link Promise} resolving when this instance was **clear**ed.
*/
public clear(): Promise<void> {
return new Promise((resolve) => this.database.transaction(() => {
this.database.prepare(`
DELETE FROM '${this.version}'
`).run();
resolve();
})());
}
/**
* Returns the current value associated with the given `key`, or null if the
* given `key` does not exist.
*
* @param key - The `key` to retrieve the current value for.
* @returns A {@link Promise} resolving to the current value or null.
*/
public getItem(key: string): Promise<string | null> {
return new Promise((resolve) => this.database.transaction(() => {
const result = this.database.prepare(`
SELECT value FROM '${this.version}' WHERE key = '${key}'
`).get() as { value: string | null } | undefined;
resolve(result?.value ?? null);
})());
}
/**
* Returns the name of the nth key, or null if n is greater than or equal to
* the number of key/value pairs.
*
* @param index - The `index` of the **key** to retrieve.
* @returns A {@link Promise} resolving to the name of the **key** or null.
*/
public key(index: number): Promise<string | null> {
return new Promise((resolve) => this.database.transaction(() => {
const result = this.database.prepare(`
SELECT key FROM '${this.version}' WHERE ROWID = '${index + 1}'
`).get() as { key: string | null } | undefined;
resolve(result?.key ?? null);
})());
}
/**
* Removes the key/value pair with the given `key`, if a key/value pair with
* the given `key` exists.
*
* @param key - The `key` to delete the key/value pair by.
* @returns A {@link Promise} resolving when the key/value pair was removed.
*/
public removeItem(key: string): Promise<void> {
return new Promise((resolve) => this.database.transaction(() => {
this.database.prepare(`
DELETE FROM '${this.version}' WHERE key = '${key}'
`).run();
resolve();
})());
}
/**
* Sets the `value` of the pair identified by `key` to `value`, creating a new
* key/value pair if none existed for `key` previously.
*
* @param key - The `key` to set the key/value pair by.
* @param value - The `value` to associate with the `key`.
* @returns A {@link Promise} resolving when the key/value pair was set.
*/
public setItem(key: string, value: string): Promise<void> {
return new Promise((resolve) => this.database.transaction(() => {
this.database.prepare(`
INSERT INTO '${this.version}' (key, value) VALUES ('${key}', '${value}')
ON CONFLICT(key) DO UPDATE SET value=excluded.value
`).run();
resolve();
})());
}
}
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