RPC, `using`, Experimental Wrangler and Observability

Murder Chicken · 2024-09-27T13:55:14.865Z

When making RPC calls through a Service Binding, it's recommended (https://developers.cloudflare.com/workers/runtime-apis/rpc/lifecycle/#how-to-use-the-using-declaration-in-your-worker) that we employ the `using` keyword to enable automatic cleanup. To use this, we're forced to use the `wrangler@using-keyword-experimental` version so that the `using` keyword is transpiled properly upon deployment. Unfortunately, this version of wrangler seems to be incompatible with the new `observability` setting that's available to us in wrangler `3.78.6`. Is there another way to handle RPC call cleanup without using the `using` keyword so that we can not bump into incompatibility with new features that are released?

M

Murder ChickenOP•9/27/24, 3:56 PM

I'm attempting to solve this without the experimental wrangler using the following code:

/**
 * Executes an RPC call and ensures proper cleanup.
 * @param {Function} rpcCall - A function that performs the RPC call.
 * @returns {Promise<any>} - The result of the RPC call.
 */
export async function executeRpcWithCleanup(rpcCall) {
  let rpcResult = null;
  try {
    rpcResult = await rpcCall();
    return rpcResult;
  } finally {
    if (rpcResult && typeof rpcResult[Symbol.dispose] === 'function') {
      console.info('Disposing RPC result');
      rpcResult[Symbol.dispose]();
    } else {
      console.info('No Symbol.dispose method on rpcResult');
    }
  }
}

/**
 * Executes an RPC call and ensures proper cleanup.
 * @param {Function} rpcCall - A function that performs the RPC call.
 * @returns {Promise<any>} - The result of the RPC call.
 */
export async function executeRpcWithCleanup(rpcCall) {
  let rpcResult = null;
  try {
    rpcResult = await rpcCall();
    return rpcResult;
  } finally {
    if (rpcResult && typeof rpcResult[Symbol.dispose] === 'function') {
      console.info('Disposing RPC result');
      rpcResult[Symbol.dispose]();
    } else {
      console.info('No Symbol.dispose method on rpcResult');
    }
  }
}

/**
 * Executes an RPC call and ensures proper cleanup.
 * @param {Function} rpcCall - A function that performs the RPC call.
 * @returns {Promise<any>} - The result of the RPC call.
 */
export async function executeRpcWithCleanup(rpcCall) {
  let rpcResult = null;
  try {
    rpcResult = await rpcCall();
    return rpcResult;
  } finally {
    if (rpcResult && typeof rpcResult[Symbol.dispose] === 'function') {
      console.info('Disposing RPC result');
      rpcResult[Symbol.dispose]();
    } else {
      console.info('No Symbol.dispose method on rpcResult');
    }
  }
}

/**
 * Executes an RPC call and ensures proper cleanup.
 * @param {Function} rpcCall - A function that performs the RPC call.
 * @returns {Promise<any>} - The result of the RPC call.
 */
export async function executeRpcWithCleanup(rpcCall) {
  let rpcResult = null;
  try {
    rpcResult = await rpcCall();
    return rpcResult;
  } finally {
    if (rpcResult && typeof rpcResult[Symbol.dispose] === 'function') {
      console.info('Disposing RPC result');
      rpcResult[Symbol.dispose]();
    } else {
      console.info('No Symbol.dispose method on rpcResult');
    }
  }
}

... and executing the method like this:

const response = await executeRpcWithCleanup(() => env.SERVICE.myRpcMethod());

const response = await executeRpcWithCleanup(() => env.SERVICE.myRpcMethod());

const response = await executeRpcWithCleanup(() => env.SERVICE.myRpcMethod());

const response = await executeRpcWithCleanup(() => env.SERVICE.myRpcMethod());

However, I'm seeing odd behavior in that the RPC methods seem to be being called twice when I view the

SERVICE

SERVICE

SERVICE

SERVICE worker's logs. When I tried an implementation of the

using

using

method, I did not see this. Not sure what's happening but anything that might cause RPC methods to be called multiple times using a single invocation of the method?

R

Radoš•9/27/24, 4:51 PM

Does

[Symbol.dispose]()

[Symbol.dispose]()

[Symbol.dispose]()

[Symbol.dispose]() works for you as it is also part of the TC39?

https://github.com/cloudflare/js-rpc-and-entrypoints-demo
In this repo, they are using it without

using

using

even with

RpcTarget

RpcTarget

RpcTarget

RpcTarget

GitHub

GitHub - cloudflare/js-rpc-and-entrypoints-demo

Contribute to cloudflare/js-rpc-and-entrypoints-demo development by creating an account on GitHub.

M

Murder ChickenOP•9/27/24, 4:52 PM

Unclear but it seems to deploy and work whereas use of

using

using

requires a different wrangler so it understands how to transpile

using

using

statements into

Symbol.dispose

Symbol.dispose

Symbol.dispose

Symbol.dispose statements.

M

Murder ChickenOP•9/27/24, 4:54 PM

So far, the approach I used above seems to work. The only odd behavior I'm seeing is duplicate log entries on the Service Worker housing the RPC methods.

M

Murder ChickenOP•9/27/24, 4:55 PM

In my use-case, I'm using Service Bindings from within a

scheduled

scheduled

scheduled

scheduled worker... IIRC they mention something about being limited to

fetch

fetch

handlers but it seems to work for me

R

Radoš•9/27/24, 4:59 PM

I have gone thru rabbit hole of sharing types between Service and Caller, but trying to call function from AuthService class thats extends

RpcTarget

RpcTarget

RpcTarget

RpcTarget resulted in

undefined

undefined

every time.

I am going to play with it in next few days, so if I stumble up on something I will let you know.

M

Murder ChickenOP•9/27/24, 5:00 PM

Are you awaiting the method call?

R

Radoš•9/27/24, 5:07 PM

Yes, when I log the call result, it shows

ProxyObject

ProxyObject

ProxyObject

ProxyObject, but then when I tried to call

result.someFunction

result.someFunction

result.someFunction

result.someFunction it was always undefined. Like it closed connection already. But maybe I was too tired and I did some rookie mistake

RPC, `using`, Experimental Wrangler and Observability

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