node-redis/lib/cluster.ts

import COMMANDS from './commands';
import { RedisCommand, RedisModules } from './commands';
import { ClientCommandOptions, RedisClientType, WithPlugins } from './client';
import { RedisSocketOptions } from './socket';
import RedisClusterSlots, { ClusterNode } from './cluster-slots';
import { RedisLuaScript, RedisLuaScripts } from './lua-script';
import { commandOptions, CommandOptions, isCommandOptions } from './command-options';

export interface RedisClusterOptions<M = RedisModules, S = RedisLuaScripts> {
    rootNodes: Array<RedisSocketOptions>;
    modules?: M;
    scripts?: S;
    useReplicas?: boolean;
    maxCommandRedirections?: number;
}

export type RedisClusterType<M extends RedisModules, S extends RedisLuaScripts> =
    WithPlugins<M, S> & RedisCluster;

export default class RedisCluster<M extends RedisModules = RedisModules, S extends RedisLuaScripts = RedisLuaScripts> {
    static defineCommand(on: any, name: string, command: RedisCommand): void {
        on[name] = async function (...args: Array<unknown>): Promise<unknown> {
            const options = isCommandOptions(args[0]) && args[0],
                redisArgs = command.transformArguments(...(options ? args.slice(1) : args));
            return command.transformReply(
                await this.sendCommand(
                    RedisCluster.#extractFirstKey(command, args, redisArgs),
                    command.IS_READ_ONLY,
                    redisArgs,
                    options
                )
            );
        };
    }

    static #extractFirstKey(commandOrScript: RedisCommand | RedisLuaScript, originalArgs: Array<unknown>, redisArgs: Array<string>): string | undefined {
        if (commandOrScript.FIRST_KEY_INDEX === undefined) {
            return undefined;
        } else if (typeof commandOrScript.FIRST_KEY_INDEX === 'number') {
            return redisArgs[commandOrScript.FIRST_KEY_INDEX];
        }

        return commandOrScript.FIRST_KEY_INDEX(...originalArgs);
    }

    static create<M extends RedisModules, S extends RedisLuaScripts>(options: RedisClusterOptions): RedisClusterType<M, S> {
        return <any>new RedisCluster(options);
    }

    static commandOptions(options: ClientCommandOptions): CommandOptions<ClientCommandOptions> {
        return commandOptions(options);
    }

    readonly #options: RedisClusterOptions;
    readonly #slots: RedisClusterSlots<M, S>;

    constructor(options: RedisClusterOptions<M, S>) {
        this.#options = options;
        this.#slots = new RedisClusterSlots(options);
        this.#initiateModules();
        this.#initiateScripts();
    }

    #initiateModules(): void {
        if (!this.#options.modules) return;

        for (const m of this.#options.modules) {
            for (const [name, command] of Object.entries(m)) {
                RedisCluster.defineCommand(this, name, command);
            }
        }
    }

    #initiateScripts(): void {
        if (!this.#options.scripts) return;

        for (const [name, script] of Object.entries(this.#options.scripts)) {
            (this as any)[name] = async function (...args: Parameters<typeof script.transformArguments>): Promise<ReturnType<typeof script.transformReply>> {
                const options = isCommandOptions(args[0]) && args[0];
                return script.transformReply(
                    await this.executeScript(
                        script,
                        args,
                        script.transformArguments(...(options ? args.slice(1) : args)),
                        options
                    )
                );
            };
        }
    }

    async connect(): Promise<void> {
        return this.#slots.connect();
    }

    async sendCommand<C extends RedisCommand>(
        firstKey: string | undefined,
        isReadonly: boolean | undefined,
        args: Array<string>,
        options?: ClientCommandOptions,
        redirections = 0
    ): Promise<ReturnType<C['transformReply']>> {
        const client = this.#slots.getClient(firstKey, isReadonly);

        try {
            return await client.sendCommand(args, options);
        } catch (err) {
            const shouldRetry = await this.#handleCommandError(err, client, redirections);
            if (shouldRetry === true) {
                return this.sendCommand(firstKey, isReadonly, args, options, redirections + 1);
            } else if (shouldRetry) {
                return shouldRetry.sendCommand(args, options);
            }

            throw err;
        }
    }

    async executeScript<S extends RedisLuaScript>(
        script: S,
        originalArgs: Array<unknown>,
        redisArgs: Array<string>,
        options?: ClientCommandOptions,
        redirections = 0
    ): Promise<ReturnType<S['transformReply']>> {
        const client = this.#slots.getClient(
            RedisCluster.#extractFirstKey(script, originalArgs, redisArgs),
            script.IS_READ_ONLY
        );

        try {
            return await client.executeScript(script, redisArgs, options);
        } catch (err) {
            const shouldRetry = await this.#handleCommandError(err, client, redirections);
            if (shouldRetry === true) {
                return this.executeScript(script, originalArgs, redisArgs, options, redirections + 1);
            } else if (shouldRetry) {
                return shouldRetry.executeScript(script, redisArgs, options);
            }

            throw err;
        }
    }

    async #handleCommandError(err: Error, client: RedisClientType<M, S>, redirections: number): Promise<boolean | RedisClientType<M, S>> {
        if (redirections > (this.#options.maxCommandRedirections ?? 16)) {
            throw err;
        }

        if (err.message.startsWith('ASK')) {
            const url = err.message.substring(err.message.lastIndexOf(' ') + 1);
            let node = this.#slots.getNodeByUrl(url);
            if (!node) {
                await this.#slots.discover(client);
                node = this.#slots.getNodeByUrl(url);

                if (!node) {
                    throw new Error(`Cannot find node ${url}`);
                }
            }

            await node.client.asking();
            return node.client;
        } else if (err.message.startsWith('MOVED')) {
            await this.#slots.discover(client);
            return client;
        }

        throw err;
    }

    getMasters(): Array<ClusterNode<M, S>> {
        return this.#slots.getMasters();
    }

    getSlotMaster(slot: number): ClusterNode<M, S> {
        return this.#slots.getSlotMaster(slot);
    }

    disconnect(): Promise<void> {
        return this.#slots.disconnect();
    }
}

for (const [name, command] of Object.entries(COMMANDS)) {
    RedisCluster.defineCommand(RedisCluster.prototype, name, command);
}