Struct FutexTable 

pub struct FutexTable { /* private fields */ }

A kernel-wide table of futexes sharded across NUM_BUCKETS hash buckets.

Each 32-bit aligned address in an address space can potentially have an associated futex that userspace can wait upon. Both private (FUTEX_PRIVATE_FLAG) and shared futexes share this table via FutexKeyValue. Each bucket holds intrusive doubly-linked lists of stack-allocated waiter nodes for internal waiters (wait, wait_boot, and lock_pi), eliminating per-process table allocations and per-wait heap allocations.

Implementations

impl FutexTable

pub fn wait_boot<Key: FutexKey>( &self, current_task: &CurrentTask, addr: UserAddress, value: u32, mask: u32, deadline: BootInstant, timer_slack: BootDuration, ) -> Result<(), Errno>

Wait on the futex at the given address given a boot deadline.

See FUTEX_WAIT when passed a deadline in CLOCK_REALTIME.

pub fn wait<Key: FutexKey>( &self, current_task: &CurrentTask, addr: UserAddress, value: u32, mask: u32, deadline: MonotonicInstant, ) -> Result<(), Errno>

Wait on the futex at the given address.

See FUTEX_WAIT.

pub fn wake<Key: FutexKey>( &self, task: &Task, addr: UserAddress, count: usize, mask: u32, ) -> Result<usize, Errno>

Wake the given number of waiters on futex at the given address. Returns the number of waiters actually woken.

See FUTEX_WAKE.

pub fn requeue<Key: FutexKey>( &self, current_task: &CurrentTask, addr: UserAddress, wake_count: usize, requeue_count: usize, new_addr: UserAddress, expected_value: Option<u32>, ) -> Result<usize, Errno>

Requeue the waiters to another address.

See FUTEX_CMP_REQUEUE

pub fn get_rt_mutex_priority_boost(&self, owner_tid: u32) -> Option<i64>

Returns the highest priority (lowest numerical task_prio value) among waiters blocked on any RT-Mutex currently owned by owner_tid, including transitive priority boosts.

pub fn lock_pi<Key: FutexKey>( &self, current_task: &CurrentTask, addr: UserAddress, deadline: MonotonicInstant, ) -> Result<(), Errno>

Lock the futex at the given address.

See FUTEX_LOCK_PI.

pub fn unlock_pi<Key: FutexKey>( &self, current_task: &CurrentTask, addr: UserAddress, ) -> Result<(), Errno>

Unlock the futex at the given address.

See FUTEX_UNLOCK_PI.

pub fn external_wait( &self, memory: MemoryObject, offset: u64, value: u32, mask: u32, ) -> Result<(Arc<()>, Receiver<()>), Errno>

Wait on the futex at the given offset in the memory.

Returns a receiver that will be signaled when the futex is woken, and an Arc<()> token that must be kept alive by the caller for the duration of the wait. If the caller drops the token (e.g., if the external client disconnects), the waiter is marked as stale and will be garbage-collected by the next futex operation on this bucket.

See FUTEX_WAIT.

pub fn external_wake( &self, memory: MemoryObject, offset: u64, count: usize, mask: u32, ) -> Result<usize, Errno>

Wake the given number of waiters on futex at the given offset in the memory. Returns the number of waiters actually woken.

See FUTEX_WAKE.

pub fn external_requeue( &self, first_memory: MemoryObject, first_offset: u64, second_memory: Option<MemoryObject>, second_offset: u64, wake_count: usize, requeue_count: usize, expected_value: Option<u32>, ) -> Result<usize, Errno>

Trait Implementations

impl Default for FutexTable

fn default() -> Self

Returns the “default value” for a type.