Struct sgx_tstd::sync::SgxCondvar

pub struct SgxCondvar { /* fields omitted */ }

A Condition Variable

Condition variables represent the ability to block a thread such that it consumes no CPU time while waiting for an event to occur. Condition variables are typically associated with a boolean predicate (a condition) and a mutex. The predicate is always verified inside of the mutex before determining that a thread must block.

Functions in this module will block the current thread of execution and are bindings to system-provided condition variables where possible. Note that this module places one additional restriction over the system condition variables: each condvar can be used with precisely one mutex at runtime. Any attempt to use multiple mutexes on the same condition variable will result in a runtime panic. If this is not desired, then the unsafe primitives in sys do not have this restriction but may result in undefined behavior.

Methods

impl SgxCondvar

pub fn new() -> Self

Creates a new condition variable which is ready to be waited on and notified.

pub fn wait<'a, T>(     &self,     guard: SgxMutexGuard<'a, T> ) -> LockResult<SgxMutexGuard<'a, T>>

Blocks the current thread until this condition variable receives a notification.

This function will atomically unlock the mutex specified (represented by guard) and block the current thread. This means that any calls to [signal] or [broadcast] which happen logically after the mutex is unlocked are candidates to wake this thread up. When this function call returns, the lock specified will have been re-acquired.

Note that this function is susceptible to spurious wakeups. Condition variables normally have a boolean predicate associated with them, and the predicate must always be checked each time this function returns to protect against spurious wakeups.

Errors

This function will return an error if the mutex being waited on is poisoned when this thread re-acquires the lock. For more information, see information about [poisoning] on the [SgxMutex] type.

Panics

This function will [panic!] if it is used with more than one mutex over time. Each condition variable is dynamically bound to exactly one mutex to ensure defined behavior across platforms. If this functionality is not desired, then unsafe primitives in sys are provided.

pub fn wait_until<'a, T, F>(     &self,     guard: SgxMutexGuard<'a, T>,     condition: F ) -> LockResult<SgxMutexGuard<'a, T>> where     F: FnMut(&mut T) -> bool,

Blocks the current thread until this condition variable receives a notification and the required condition is met. Spurious wakeups are ignored and this function will only return once the condition has been met.

This function will atomically unlock the mutex specified (represented by guard) and block the current thread. This means that any calls to [signal] or [broadcast] which happen logically after the mutex is unlocked are candidates to wake this thread up. When this function call returns, the lock specified will have been re-acquired.

Errors

This function will return an error if the mutex being waited on is poisoned when this thread re-acquires the lock. For more information, see information about [poisoning] on the [Mutex] type.

pub fn signal(&self)

Wakes up one blocked thread on this condvar.

If there is a blocked thread on this condition variable, then it will be woken up from its call to [wait]. Calls to signal are not buffered in any way.

To wake up all threads, see [broadcast].

pub fn broadcast(&self)

Wakes up all blocked threads on this condvar.

This method will ensure that any current waiters on the condition variable are awoken. Calls to broadcast() are not buffered in any way.

To wake up only one thread, see [signal].

Trait Implementations

impl Debug for SgxCondvar

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Default for SgxCondvar

fn default() -> Self

Creates a Condvar which is ready to be waited on and notified.

impl Drop for SgxCondvar

fn drop(&mut self)

Executes the destructor for this type.