Trait Filter

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pub trait Filter: 'static {
    // Required methods
    fn query(&self, id: TypeId) -> Option<Box<dyn Any>>;
    fn process_read_buf(&self, ctx: &mut FilterCtx<'_>) -> Result<()>;
    fn process_write_buf(&self, ctx: &mut FilterCtx<'_>) -> Result<()>;
    fn shutdown(&self, ctx: &mut FilterCtx<'_>) -> Result<Poll<()>>;
    fn poll_read_ready(&self, cx: &mut Context<'_>) -> Poll<Readiness>;
    fn poll_write_ready(&self, cx: &mut Context<'_>) -> Poll<Readiness>;
}

Expand description

Complete filter-chain interface used by Io.

Most filters should implement FilterLayer and be installed with Io::add_filter. Implement this trait directly only when wrapping or replacing a complete chain.

Required Methods§

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fn query(&self, id: TypeId) -> Option<Box<dyn Any>>

Returns type-indexed information exposed by this chain.

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fn process_read_buf(&self, ctx: &mut FilterCtx<'_>) -> Result<()>

Processes incoming data from the transport toward the application.

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fn process_write_buf(&self, ctx: &mut FilterCtx<'_>) -> Result<()>

Processes outgoing data from the application toward the transport.

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fn shutdown(&self, ctx: &mut FilterCtx<'_>) -> Result<Poll<()>>

Performs graceful shutdown from the outermost layer toward the transport.

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fn poll_read_ready(&self, cx: &mut Context<'_>) -> Poll<Readiness>

Checks whether transport read operations may proceed.

Reads continue through the filter shutdown phase so that filters can complete theirs, and are paused for the transport shutdown phase, so Readiness::Close is resolved only once the connection is terminated. A force close reports Readiness::Terminate instead, which releases the connection without a graceful close. That decision is made by IoContext rather than by the chain, so that it survives the chain being dropped along with Io.

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fn poll_write_ready(&self, cx: &mut Context<'_>) -> Poll<Readiness>

Checks whether transport write operations may proceed.

Resolves to Readiness::Close once the connection enters a graceful shutdown and all buffered output has reached the transport, or as soon as it ends because of a failure. See poll_read_ready for the force-close case.