Semaphore in Go

Description

The Semaphore is a synchronization primitive that allows controlling access to a shared resource. It maintains a count representing the number of available resources and provides two main operations: Acquire and Release. The Acquire operation requests to acquire a resource from the semaphore, blocking if none is currently available, and the Release operation signals that a resource is released and becomes available for other goroutines to acquire.

In this Go implementation of the Semaphore, a count-based semaphore is implemented using a mutex and a condition variable. The NewSemaphore function creates a new semaphore with the specified initial count, and the Acquire and Release methods are used to acquire and release resources, respectively.

Usage

To use the Semaphore in your Go program, follow these steps:

1. Create a new semaphore using the NewSemaphore function, passing the initial count of available resources as an argument.
2. Call the Acquire method to acquire a resource from the semaphore. If no resources are available, the calling goroutine will be blocked until a resource becomes available.
3. Perform the necessary operations with the acquired resource.
4. Call the Release method to release the resource back to the semaphore, making it available for other goroutines to acquire.

Example: Concurrent Task Execution with Semaphore

The following example demonstrates the usage of Semaphore by simulating concurrent task execution with limited resources.

Task Function

The ExampleTask function represents a task that requires acquiring the semaphore to perform its work. In this example, the task simply prints a message indicating its progress.

Main Function

In the main function, a semaphore instance is created using the NewSemaphore function with an initial count of available resources. Four goroutines are then started, representing concurrent tasks. Each task calls the ExampleTask function, acquires the semaphore, performs its work (represented by a sleep in this example), and releases the semaphore when finished. The program waits for all tasks to complete using a sync.WaitGroup. go run semaphore.go