remove async_trait from ExchangeSource

[lmatz]

https://github.com/singularity-data/risingwave/blob/main/rust/rpc_client/src/compute_client.rs#L128-L132

/// Each ExchangeSource maps to one task, it takes the execution result from task chunk by chunk.
#[async_trait::async_trait]
pub trait ExchangeSource: Send {
    async fn take_data(&mut self) -> Result<Option<DataChunk>>;
}

take_data gets frequently called and is on the critical path. We may need to remove the overhead of async_trait.

Same as what #1132 did.

[KivenChen]

Hi @lmatz! May I try to resolve this issue? The intuition behind it seems similar to this tutorial: https://www.skyzh.dev/posts/articles/2022-01-31-gat-async-trait/

[lmatz]

Hi @lmatz! May I try to resolve this issue? The intuition behind it seems similar to this tutorial: https://www.skyzh.dev/posts/articles/2022-01-31-gat-async-trait/

Sure!

[KivenChen]

A PR has been created to solve this issue. PTAL #3586