Changelog #103

·

Run cleanup using onCancel hook

Define an onCancel hook that is called when a run is canceled

Eric Allam

Eric Allam

CTO, Trigger.dev

Image for Run cleanup using onCancel hook

You can now define an onCancel hook that is called when a run is canceled. This is useful if you want to clean up any resources that were allocated for the run.


tasks.onCancel(({ ctx, signal }) => {
console.log("Run canceled", signal);
});

The onCancel hook can be used to interrupt calls to external services. For example, when using the streamText function from the AI SDK:


import { logger, tasks, schemaTask } from "@trigger.dev/sdk";
import { streamText } from "ai";
import { z } from "zod";
export const interruptibleChat = schemaTask({
id: "interruptible-chat",
description: "Chat with the AI",
schema: z.object({
prompt: z.string().describe("The prompt to chat with the AI"),
}),
run: async ({ prompt }, { signal }) => {
const chunks: TextStreamPart<{}>[] = [];
tasks.onCancel(async () => {
// We have access to the chunks here, and can save them to the database
await saveChunksToDatabase(chunks);
});
try {
const result = streamText({
model: getModel(),
prompt,
experimental_telemetry: {
isEnabled: true,
},
tools: {},
abortSignal: signal, // Pass the signal to the streamText function
onChunk: ({ chunk }) => {
chunks.push(chunk);
},
});
const textParts = [];
for await (const part of result.textStream) {
textParts.push(part);
}
return textParts.join("");
} catch (error) {
if (error instanceof Error && error.name === "AbortError") {
// Handle abort error
} else {
throw error;
}
}
},
});

You can also use the onCancel hook to wait for the run function to finish and access its output:


import { logger, task } from "@trigger.dev/sdk";
import { setTimeout } from "node:timers/promises";
export const cancelExampleTask = task({
id: "cancel-example",
run: async (payload: { message: string }, { signal }) => {
try {
await setTimeout(10_000, undefined, { signal });
} catch (error) {
// Ignore the abort error
}
return {
message: "Hello, world!",
};
},
onCancel: async ({ runPromise }) => {
// You can await the runPromise to get the output of the task
const output = await runPromise;
},
});

Note: You have up to 30 seconds to complete the runPromise in the onCancel hook. After that point the process will be killed.

This feature is only available in v4.0.0-beta.12 and later.

View the docs

#102

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