class
Sync::Exclusive(T)
- Sync::Exclusive(T)
- Reference
- Object
Overview
Safely share a value T
across fibers and execution contexts using a
Mutex
, so only one critical section can access the value at any time.
For example:
require "sync/exclusive"
class Queue
@@running : Sync::Exclusive.new([] of Queue)
def self.on_started(queue)
@@running.get(&.push(queue))
end
def self.on_stopped(queue)
@@running.get(&.delete(queue))
end
def self.each(&)
@@running.get do |list|
list.each { |queue| yield queue }
end
end
end
Consider an Exclusive(T)
if your workload mostly needs to own the value,
and most, if not all, critical sections need to mutate the inner state of
the value for example.
Included Modules
Defined in:
exclusive.crConstructors
Instance Method Summary
-
#clone_value : T
Locks the mutex and returns a deep copy of the value.
-
#dup_value : T
Locks the mutex and returns a shallow copy of the value.
-
#get(& : T -> U) : U forall U
Locks the mutex and yields the value.
-
#replace(& : T -> T) : Nil
Locks the mutex, yields the value and eventually replaces the value with the one returned by the block.
-
#set(value : T) : Nil
Locks the mutex and sets the value.
-
#unsafe_get : T
Returns the value without any synchronization.
-
#unsafe_set(value : T) : T
Sets the value without any synchronization.
-
#value : T
Locks the mutex and returns the value.
Constructor Detail
Instance Method Detail
Locks the mutex and returns a deep copy of the value. The lock is released before returning the new value.
@[Experimental("The method may not have much value over #get(&.clone)")]
Locks the mutex and returns a shallow copy of the value. The lock is released before returning the new value.
Sometimes it may not be needed to own the value (no need to mutate it, or the value is returned by copy anyway), and taking a copy can help release the lock early, instead of keeping the lock acquired for a while, preventing progress of other fibers.
@[Experimental("The method may not have much value over #get(&.dup)")]
Locks the mutex and yields the value. The lock is released before returning.
The value is owned for the duration of the block, and can be safely mutated.
WARNING The value musn't be retained and accessed after the block has returned.
Locks the mutex, yields the value and eventually replaces the value with the one returned by the block. The lock is released before returning.
The current value is now owned: it can be safely retained and mutated even after the block returned.
WARNING The new value musn't be retained and accessed after the block has returned.
Locks the mutex and sets the value. Unlocks the mutex before returning.
Always acquires and releases the lock, so writing the value is always synchronized with the other methods.
Returns the value without any synchronization.
WARNING Breaks the mutual exclusion constraint. Only use when you can guarantee that the current fiber acquired the lock or to access a value that can be read in a single load operation from memory.
Sets the value without any synchronization.
WARNING Breaks the mutual exclusion constraint. Only use when you can guarantee that the current fiber acquired the lock or to access a value that can be written in a single store operation into memory.
Locks the mutex and returns the value. Unlocks before returning.
Always acquires the lock, so reading the value is synchronized in relation
with the other methods. However, safely accessing the returned value
entirely depends on the safety of T
, which should be Sync::Safe
.
Prefer #dup_value
or #clone_value
to get a shallow or deep copy of the
value instead.
WARNING Breaks the mutual exclusion guarantee since the returned value outlives the lock, the value can be accessed concurrently to the synchronized methods.
@[Experimental("The method may not have much value over #get(&.itself)")]