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// Copyright (c) 2017-2024 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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// Test to validate timing semantics for JSRPC invocations with streaming responses.
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// This test verifies that the Return event is emitted at the correct time relative
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// to Onset and Outcome events.
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//
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// Expected timeline:
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//   T=0:      Onset (invocation starts)
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//   T=~500ms: Return (handler returns the stream)
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//   T=~950ms: Outcome (stream fully consumed)
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import { WorkerEntrypoint } from 'cloudflare:workers';
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export class StreamingService extends WorkerEntrypoint {
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  async getStreamWithDelays() {
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    // Sleep 500ms before returning the stream
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    await scheduler.wait(500);
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    // Return a ReadableStream that takes ~450ms to drain
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    const encoder = new TextEncoder();
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    let chunksSent = 0;
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    const stream = new ReadableStream({
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      async pull(controller) {
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        if (chunksSent >= 3) {
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          controller.close();
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          return;
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        }
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        // Sleep 150ms between chunks (3 chunks = ~450ms to drain)
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        await scheduler.wait(150);
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        controller.enqueue(encoder.encode(`chunk${chunksSent++}\n`));
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      },
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    });
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    return stream;
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  }
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}
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export default {
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  async test(controller, env, ctx) {
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    // Call the streaming RPC method
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    const stream = await env.StreamingService.getStreamWithDelays();
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    // Consume the stream fully
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    const reader = stream.getReader();
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    let chunks = [];
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    while (true) {
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      const { done, value } = await reader.read();
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      if (done) break;
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      chunks.push(new TextDecoder().decode(value));
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    }
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    // Verify we got all chunks
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    if (chunks.length !== 3) {
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      throw new Error(`Expected 3 chunks, got ${chunks.length}`);
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    }
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    // The actual timing validation is done in the tail worker's test() handler
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  },
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};