@temporalio/workflow/lib/sinks.js

Temporal.io SDK Workflow sub-package

"use strict";
/**
 * Type definitions for the Workflow end of the sinks mechanism.
 *
 * Sinks are a mechanism for exporting data from the Workflow isolate to the
 * Node.js environment, they are necessary because the Workflow has no way to
 * communicate with the outside World.
 *
 * Sinks are typically used for exporting logs, metrics and traces out from the
 * Workflow.
 *
 * Sink functions may not return values to the Workflow in order to prevent
 * breaking determinism.
 *
 * @module
 */
Object.defineProperty(exports, "__esModule", { value: true });
exports.proxySinks = proxySinks;
const global_attributes_1 = require("./global-attributes");
/**
 * Get a reference to Sinks for exporting data out of the Workflow.
 *
 * These Sinks **must** be registered with the Worker in order for this
 * mechanism to work.
 *
 * @example
 * ```ts
 * import { proxySinks, Sinks } from '@temporalio/workflow';
 *
 * interface MySinks extends Sinks {
 *   logger: {
 *     info(message: string): void;
 *     error(message: string): void;
 *   };
 * }
 *
 * const { logger } = proxySinks<MyDependencies>();
 * logger.info('setting up');
 *
 * export function myWorkflow() {
 *   return {
 *     async execute() {
 *       logger.info("hey ho");
 *       logger.error("lets go");
 *     }
 *   };
 * }
 * ```
 */
function proxySinks() {
    return new Proxy({}, {
        get(_, ifaceName) {
            return new Proxy({}, {
                get(_, fnName) {
                    return (...args) => {
                        const activator = (0, global_attributes_1.assertInWorkflowContext)('Proxied sinks functions may only be used from a Workflow Execution.');
                        activator.sinkCalls.push({
                            ifaceName: ifaceName,
                            fnName: fnName,
                            // Sink function doesn't get called immediately. Make a clone of the sink's args, so that further mutations
                            // to these objects don't corrupt the args that the sink function will receive. Only available from node 17.
                            args: globalThis.structuredClone ? globalThis.structuredClone(args) : args,
                            // activator.info is internally copy-on-write. This ensure that any further mutations
                            // to the workflow state in the context of the present activation will not corrupt the
                            // workflowInfo state that gets passed when the sink function actually gets called.
                            workflowInfo: activator.info,
                        });
                    };
                },
            });
        },
    });
}
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