Struct Channel

pub(crate) struct Channel<T> {
    head: CachePadded<Atomic<usize>>,
    tail: CachePadded<Atomic<usize>>,
    buffer: Box<[Slot<T>]>,
    cap: usize,
    one_lap: usize,
    mark_bit: usize,
    senders: SyncWaker,
    receivers: SyncWaker,
}

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Bounded channel based on a preallocated array.

Fields

head: CachePadded<Atomic<usize>>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

The head of the channel.

This value is a “stamp” consisting of an index into the buffer, a mark bit, and a lap, but packed into a single usize. The lower bits represent the index, while the upper bits represent the lap. The mark bit in the head is always zero.

Messages are popped from the head of the channel.

tail: CachePadded<Atomic<usize>>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

The tail of the channel.

This value is a “stamp” consisting of an index into the buffer, a mark bit, and a lap, but packed into a single usize. The lower bits represent the index, while the upper bits represent the lap. The mark bit indicates that the channel is disconnected.

Messages are pushed into the tail of the channel.

buffer: Box<[Slot<T>]>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

The buffer holding slots.

cap: usize

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

The channel capacity.

one_lap: usize

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

A stamp with the value of { lap: 1, mark: 0, index: 0 }.

mark_bit: usize

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

If this bit is set in the tail, that means the channel is disconnected.

senders: SyncWaker

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Senders waiting while the channel is full.

receivers: SyncWaker

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Receivers waiting while the channel is empty and not disconnected.

Implementations

impl<T> Channel<T>

pub(crate) fn with_capacity(cap: usize) -> Self

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Creates a bounded channel of capacity cap.

fn start_send(&self, token: &mut Token) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Attempts to reserve a slot for sending a message.

pub(crate) unsafe fn write(&self, token: &mut Token, msg: T) -> Result<(), T>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Writes a message into the channel.

fn start_recv(&self, token: &mut Token) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Attempts to reserve a slot for receiving a message.

pub(crate) unsafe fn read(&self, token: &mut Token) -> Result<T, ()>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Reads a message from the channel.

pub(crate) fn try_send(&self, msg: T) -> Result<(), TrySendError<T>>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Attempts to send a message into the channel.

pub(crate) fn send( &self, msg: T, deadline: Option<Instant>, ) -> Result<(), SendTimeoutError<T>>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Sends a message into the channel.

pub(crate) fn try_recv(&self) -> Result<T, TryRecvError>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Attempts to receive a message without blocking.

pub(crate) fn recv( &self, deadline: Option<Instant>, ) -> Result<T, RecvTimeoutError>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Receives a message from the channel.

pub(crate) fn len(&self) -> usize

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Returns the current number of messages inside the channel.

pub(crate) fn capacity(&self) -> Option<usize>

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Returns the capacity of the channel.

pub(crate) fn disconnect_senders(&self) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Disconnects senders and wakes up all blocked receivers.

Returns true if this call disconnected the channel.

pub(crate) unsafe fn disconnect_receivers(&self) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Disconnects receivers and wakes up all blocked senders.

Returns true if this call disconnected the channel.

Safety

May only be called once upon dropping the last receiver. The destruction of all other receivers must have been observed with acquire ordering or stronger.

unsafe fn discard_all_messages(&self, tail: usize)

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Discards all messages.

tail should be the current (and therefore last) value of tail.

Panicking

If a destructor panics, the remaining messages are leaked, matching the behavior of the unbounded channel.

Safety

This method must only be called when dropping the last receiver. The destruction of all other receivers must have been observed with acquire ordering or stronger.

pub(crate) fn is_disconnected(&self) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Returns true if the channel is disconnected.

pub(crate) fn is_empty(&self) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Returns true if the channel is empty.

pub(crate) fn is_full(&self) -> bool

🔬This is a nightly-only experimental API. (mpmc_channel #126840)

Returns true if the channel is full.