A TSemaphore is a semaphore that can be composed transactionally. Because of the extremely high performance of ZIO's implementation of software transactional memory TSemaphore can support both controlling access to some resource on a standalone basis as well as composing with other STM data structures to solve more advanced concurrency problems.
For basic use cases, the most idiomatic way to work with a semaphore is to use the withPermit operator, which acquires a permit before executing some ZIO effect and release the permit immediately afterward. The permit is guaranteed to be released immediately after the effect completes execution, whether by success, failure, or interruption. Attempting to acquire a permit when a sufficient number of permits are not available will semantically block until permits become available without blocking any underlying operating system threads. If you want to acquire more than one permit at a time you can use withPermits, which allows specifying a number of permits to acquire. You can also use withPermitScoped or withPermitsScoped to acquire and release permits within the context of a scoped effect for composing with other resources.
For more advanced concurrency problems you can use the acquire and release operators directly, or their variants acquireN and releaseN, all of which return STM transactions. Thus, they can be composed to form larger STM transactions, for example acquiring permits from two different semaphores transactionally and later releasing them transactionally to safely synchronize on access to two different mutable variables.
Attributes
- Companion
- object
- Graph
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- Supertypes
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trait Serializableclass Objecttrait Matchableclass Any