Bump tokio from 0.2.11 to 0.2.12

[dependabot-preview[bot]]

Bumps tokio from 0.2.11 to 0.2.12.

Release notes

Sourced from tokio's releases.

Tokio v0.2.12

Polish, small additions, and fixes. The biggest additions in this release are StreamMap and Notify.

StreamMap

Similar to StreamExt::merge, StreamMap supports merging multiple source streams into a single stream, producing items as they become available in the source streams. However, StreamMap supports inserting and removing streams at run-time. This is useful for cases where a consumer wishes to subscribe to messages from multiple sources and dynamically manage those subscriptions.

As the name implies, StreamMap maps keys to streams. Streams are [inserted] or [removed] as needed and then the StreamMap is used as any other stream. Items are returned with their keys, enabling the caller to identify which source stream the item originated from.

Example

use tokio::stream::{StreamExt, StreamMap};
use tokio::sync::mpsc;
#[tokio::main]
async fn main() {
let (mut tx1, rx1) = mpsc::channel(10);
let (mut tx2, rx2) = mpsc::channel(10);
// use Sender handles
let mut map = StreamMap::new();

// Insert both streams
map.insert("one", rx1);
map.insert("two", rx2);

// Read twice
for _ in 0..2 {
    let (key, val) = map.next().await.unwrap();

    println!("got {} from {}", val, key);

    // Remove the stream to prevent reading the next value
    map.remove(key);
}

}

Notify

Notify is the next step in providing async / await based synchronization primitives. It is similar to how thread::park() / unpark() work, but for asynchronous tasks. Consumers await notifications and producers notify consumers. Notify is intended to be used as a building block for higher level synchronization primitives, such as channels.

Examples

Basic usage.

use tokio::sync::Notify;
use std::sync::Arc;
</tr></table> ... (truncated)

Commits

• c6fc1db chore: prepare v0.2.12 release (#2278)
• d44ce33 tcp: Update listener docs (#2276)
• 8b7ea0f sync: adds Notify for basic task notification (#2210)
• 7207bf3 time: avoid needing to poll DelayQueue after insertion (#2217)
• a4c4ac2 docs: macros doc(cfg) workarounds (#2225)
• 0589acc Implement Stream for Listener types (#2275)
• 1dadc70 macros: add assignment form to pin! (#2274)
• 10f1507 process: Wake up read and write on EPOLLERR (#2218)
• b9cc032 mpsc: add Sender::send_timeout (#2227)
• 4213b79 tokio: fix broken contributing guide link (#2267)
• Additional commits viewable in compare view

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