Simple subrequest support

[ensh63]

• Typed storage in Pool with cleanup support;
• Request context support for HTTP phase modules;
• Simple version of HTTP subrequest support:
  • subrequest builder;
  • subrequest handler with support of user-supplied function or closure;
  • example of use;
• refactoring for Status conversions

[Copilot]

Pull request overview

This PR introduces subrequest support for nginx Rust bindings along with typed storage in Pool and request context management. The changes enable HTTP modules to create and manage subrequests with user-defined handlers, while also adding infrastructure for request-specific context data and improved pool memory management.

Changes:

• Adds HTTP subrequest builder API with support for in-memory, waited, and background subrequests
• Implements RequestContext trait for type-safe, module-scoped request context management with automatic cleanup
• Enhances Pool with typed storage methods (allocate, get_or_add_unique, remove) using cleanup handlers for RAII

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/http/subrequest.rs	New subrequest builder and handler implementation with memory-pool-based allocation
src/http/request_context.rs	RequestContext trait for managing typed request-specific data
src/http/request.rs	Added get_main/get_main_mut, get_status methods and Result<T,E> IntoHandlerStatus impl
src/http/status.rs	Refactored to use TryFrom trait instead of custom from_* methods, simplified error type
src/http/mod.rs	Exports new subrequest and request_context modules
src/core/pool.rs	Enhanced with typed allocation, unique value storage, and cleanup management
src/log.rs	Updated macro to use safe log() method instead of unsafe pointer access
examples/subrequest.rs	Example demonstrating subrequest usage with context management
examples/Cargo.toml	Added subrequest example configuration

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 6 comments.

Comments suppressed due to low confidence (1)

src/http/status.rs:84

• The refactoring removes the public methods HTTPStatus::from_u16 and HTTPStatus::from_bytes and replaces them with TryFrom trait implementations. This is a breaking API change that could affect existing users of the library. Consider either keeping the old methods as wrappers around the new TryFrom implementations for backward compatibility, or documenting this breaking change in the PR description and release notes.

impl TryFrom<usize> for HTTPStatus {
    type Error = InvalidHTTPStatusCode;

    #[inline]
    fn try_from(value: usize) -> Result<Self, Self::Error> {
        if !(100..600).contains(&value) {
            return Err(InvalidHTTPStatusCode);
        }
        Ok(HTTPStatus(value))
    }
}

impl TryFrom<isize> for HTTPStatus {
    type Error = InvalidHTTPStatusCode;

    #[inline]
    fn try_from(value: isize) -> Result<Self, Self::Error> {
        let value: usize = value.try_into().map_err(|_| InvalidHTTPStatusCode)?;
        Self::try_from(value)
    }
}

impl TryFrom<&[u8]> for HTTPStatus {
    type Error = InvalidHTTPStatusCode;

    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
        if value.len() != 3 {
            return Err(InvalidHTTPStatusCode);
        }

        let a = value[0].wrapping_sub(b'0') as u16;
        let b = value[1].wrapping_sub(b'0') as u16;
        let c = value[2].wrapping_sub(b'0') as u16;

        if a == 0 || a > 5 || b > 9 || c > 9 {
            return Err(InvalidHTTPStatusCode);
        }

        let status = (a * 100) + (b * 10) + c;
        Ok(HTTPStatus(status.into()))
    }
}

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