Cloudflare DevelopersCD
Cloudflare Developers•2y ago
kian

In Workers, the only thing that's isolated is within your `fetch` handler which is it's own "asynchr

In Workers, the only thing that's isolated is within your 
fetch
 handler which is it's own "asynchronous duration" - it's an async function, basically called by the runtime.

When you call als.run(..., async () => { ... }); inside your 
fetch
 handler, als keeps track of what context it was called in (this specific call of the 
fetch
 handler).

When your other modules are calling als.getStore(), those modules were called within that run callback - it's tied to that invocation of the 
fetch
 handler.

If you tried calling als.getStore() within the 
fetch
 handler but outside of the run callback, it'd be 
undefined
. run stores what you pass to it in a context that's only available to the callback, and other calls to run by other requests doesn't mutate our store since als knows that is a separate invocation of the 
fetch
 handler.
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