Rust client SDK ReducerInfo enum
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This requires deriving `Debug` for tables and generated types. In the future, we should be careful that all spacetime types can derive `Debug`.
Prior to this commit, callbacks in the Rust client SDK shared access to the global ClientCache while running asynchronously. This meant that a long-running or delayed callback could observe the ClientCache in a state later than the one that caused the callback's invocation, and had no way to access the specific state for which it was invoked. With this commit, each `Invoke` message to the callback worker includes an `Arc<ClientCache>` snapshot of the DB state when that callback was invoked. The callback worker stores that state in a `thread_local`, and methods that inspect tables (e.g. `TableType::iter`) read the state out of the `thread_local` when it is present. This allows callbacks to observe exactly the state which caused their invocation, never a later state, while maintaining the C#-like API where `ClientCache` access is based on free functions or static trait methods.
With this commit, row callbacks (`on_insert`, `on_delete`, `on_update`) in the Rust client SDK take an additional argument, `Option<&ReducerEvent>`, where `ReducerEvent` is an enum generated by the CLI's codegen with a variant for each reducer defined in the module. Having the SDK pass around an autogenerated type in this way (without adding a bunch of `<ReducerEvent>` generic parameters everywhere) requires storing the `ReducerEvent` in an `Arc<dyn Any>`. This has the added tangential benefit of avoiding cloning the `ReducerEvent` for each row callback.
Centril
reviewed
Jun 27, 2023
jdetter
approved these changes
Jun 30, 2023
cloutiertyler
pushed a commit
that referenced
this pull request
Aug 1, 2023
* `ReducerEvent` enum in Rust client SDK With this commit, row callbacks (`on_insert`, `on_delete`, `on_update`) in the Rust client SDK take an additional argument, `Option<&ReducerEvent>`, where `ReducerEvent` is an enum generated by the CLI's codegen with a variant for each reducer defined in the module. Having the SDK pass around an autogenerated type in this way (without adding a bunch of `<ReducerEvent>` generic parameters everywhere) requires storing the `ReducerEvent` in an `Arc<dyn Any>`. This has the added tangential benefit of avoiding cloning the `ReducerEvent` for each row callback.
cloutiertyler
pushed a commit
that referenced
this pull request
Aug 1, 2023
* `ReducerEvent` enum in Rust client SDK With this commit, row callbacks (`on_insert`, `on_delete`, `on_update`) in the Rust client SDK take an additional argument, `Option<&ReducerEvent>`, where `ReducerEvent` is an enum generated by the CLI's codegen with a variant for each reducer defined in the module. Having the SDK pass around an autogenerated type in this way (without adding a bunch of `<ReducerEvent>` generic parameters everywhere) requires storing the `ReducerEvent` in an `Arc<dyn Any>`. This has the added tangential benefit of avoiding cloning the `ReducerEvent` for each row callback.
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Description of Changes
Depends on #16 .
This PR adds an autogenerated
enum ReducerInfowith a variant for each reducer defined by a module as an additional argument to row callbacks (on_insert,on_deleteandon_update).API
If the API is breaking, please state below what will break
Row callbacks in the Client SDK take an additional argument now, so an
_will have to be added to closure arglists.