Prepare Tokio v1.5.0

[Darksonn]

1.5.0 (April 12, 2021)

Added

• io: add AsyncSeekExt::stream_position (io: add AsyncSeekExt::stream_position #3650)
• io: add AsyncWriteExt::write_vectored (io: add AsyncWriteExt::write_vectored #3678)
• io: add a copy_bidirectional utility (io: add a copy_bidirectional utility #3572)
• net: implement IntoRawFd for TcpSocket (net: implements IntoRawFd for TcpSocket #3684)
• sync: add OnceCell (Add OnceCell #3591)
• sync: add OwnedRwLockReadGuard and OwnedRwLockWriteGuard (Add OwnedRwLockReadGuard and OwnedRwLockWriteGuard #3340)
• sync: add Semaphore::is_closed (Add Semaphore::is_closed method #3673)
• sync: add mpsc::Sender::capacity (sync: add mpsc::Sender::capacity #3690)
• sync: allow configuring RwLock max reads (Allow to configure RwLock max reads #3644)
• task: add sync_scope for LocalKey (Add sync_scope for LocalKey #3612)

Fixed

• chore: try to avoid noalias attributes on intrusive linked list (Try to avoid noalias attributes on intrusive linked lists #3654)
• rt: fix panic in JoinHandle::abort() when called from other threads (Prevent basic_scheduler from panicking if a task is aborted from another thread #3672)
• sync: don't panic in oneshot::try_recv (Remove panic from oneshot receiver #3674)
• sync: fix notifications getting dropped on receiver drop (sync: fix notification permit getting dropped on receiver drop #3652)

Documented

• io: clarify requirements of AsyncFd (doc: Clarify requirements of AsyncFd #3635)
• runtime: fix unclear docs for {Handle,Runtime}::block_on (runtime: fix unclear docs for {Handle,Runtime}::block_on #3628)
• sync: document that Semaphore is fair (Document that Semaphore is fair #3693)
• sync: improve doc on blocking mutex ((minor) amendments to Mutex docs #3645)

[carllerche]

As a minor bikeshed point (belated) re: RwLock::new_with_max_reads, we don't really have any public new_with fns and std seems to only have ::with_ (e.g. Vec::with_capacity).

So, my vote would be: RwLock::with_max_readers instead of reads as the RwLock can have more than that total reads :)

Anyway, this isn't a hard block, we can always rename later w/ a deprecation process.

[Darksonn]

Good point. I just renamed it here.