micropelago/tokio-rustls
3
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Add poll_write docs (#73)

Browse Source
This commit is contained in:
quininer 2021-10-15 02:15:39 +08:00 committed by GitHub
parent ea14b430d7
commit 48caaf751f
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 36 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
tokio-rustls/src/lib.rs
View File

@ -1,4 +1,40 @@
//! Asynchronous TLS/SSL streams for Tokio using [Rustls](https://github.com/ctz/rustls).
//!
//! # Why do I need to call `poll_flush`?
//!
//! Most TLS implementations will have an internal buffer to improve throughput,
//! and rustls is no exception.
//!
//! When we write data to `TlsStream`, we always write rustls buffer first,
//! then take out rustls encrypted data packet, and write it to data channel (like TcpStream).
//! When data channel is pending, some data may remain in rustls buffer.
//!
//! `tokio-rustls` To keep it simple and correct, [TlsStream] will behave like `BufWriter`.
//! For `TlsStream<TcpStream>`, this means that data written by `poll_write` is not guaranteed to be written to `TcpStream`.
//! You must call `poll_flush` to ensure that it is written to `TcpStream`.
//!
//! You should call `poll_flush` at the appropriate time,
//! such as when a period of `poll_write` write is complete and there is no more data to write.
//!
//! ## Why don't we write during `poll_read`?
//!
//! We did this in the early days of `tokio-rustls`, but it caused some bugs.
//! We can solve these bugs through some solutions, but this will cause performance degradation (reverse false wakeup).
//!
//! And reverse write will also prevent us implement full duplex in the future.
//!
//! see <https://github.com/tokio-rs/tls/issues/40>
//!
//! ## Why can't we handle it like `native-tls`?
//!
//! When data channel returns to pending, `native-tls` will falsely report the number of bytes it consumes.
//! This means that if data written by `poll_write` is not actually written to data channel, it will not return `Ready`.
//! Thus avoiding the call of `poll_flush`.
//!
//! but which does not conform to convention of `AsyncWrite` trait.
//! This means that if you give inconsistent data in two `poll_write`, it may cause unexpected behavior.
//!
//! see <https://github.com/tokio-rs/tls/issues/41>
macro_rules! ready {
( $e:expr ) => {