Rollup merge of #45969 - ia0:mpsc_recv_deadline, r=alexcrichton

Add std::sync::mpsc::Receiver::recv_deadline()

Essentially renames recv_max_until to recv_deadline (mostly copying recv_timeout
documentation). This function is useful to avoid the often unnecessary call to
Instant::now in recv_timeout (e.g. when the user already has a deadline). A
concrete example would be something along those lines:

```rust
use std::sync::mpsc::Receiver;
use std::time::{Duration, Instant};

/// Reads a batch of elements
///
/// Returns as soon as `max_size` elements have been received or `timeout` expires.
fn recv_batch_timeout<T>(receiver: &Receiver<T>, timeout: Duration, max_size: usize) -> Vec<T> {
    recv_batch_deadline(receiver, Instant::now() + timeout, max_size)
}

/// Reads a batch of elements
///
/// Returns as soon as `max_size` elements have been received or `deadline` is reached.
fn recv_batch_deadline<T>(receiver: &Receiver<T>, deadline: Instant, max_size: usize) -> Vec<T> {
    let mut result = Vec::new();
    while let Ok(x) = receiver.recv_deadline(deadline) {
        result.push(x);
        if result.len() == max_size {
            break;
        }
    }
    result
}
```

0 files changed, 0 insertions, 0 deletions