Semaphore pattern implementation with timeout of lock/unlock operations.
The semaphore provides API to control access to a shared resource by multiple goroutines or limit throughput.
releaser, err := semaphore.Acquire(breaker.BreakByTimeout(time.Second))
if err != nil {
// timeout exceeded
}
defer releaser.Release()Full description of the idea is available here.
...
limiter := semaphore.New(1000)
http.HandleFunc("/", func(rw http.ResponseWriter, req *http.Request) {
if _, err := limiter.Acquire(
breaker.BreakByContext(
context.WithTimeout(req.Context(), time.Second),
),
); err != nil {
http.Error(rw, http.StatusText(http.StatusTooManyRequests), http.StatusTooManyRequests)
return
}
defer limiter.Release()
// handle request
})
log.Fatal(http.ListenAndServe(":80", http.DefaultServeMux))The library uses SemVer for versioning, and it is not BC-safe through major releases. You can use go modules or dep to manage its version.
The master is a feature frozen branch for versions 4.3.x and no longer maintained.
$ dep ensure -add github.com/kamilsk/[email protected]The v4 branch is a continuation of the master branch for versions v4.4.x to better integration with go modules.
$ go get -u github.com/kamilsk/semaphore/[email protected]The v5 branch is an actual development branch.
$ go get -u github.com/kamilsk/semaphore # inside GOPATH and for old Go versions
$ go get -u github.com/kamilsk/semaphore/v5 # inside Go module, works well since Go 1.11
$ dep ensure -add github.com/kamilsk/[email protected]Version v5 focused on integration with the 🚧 breaker package.
This example shows how to execute many console commands in parallel.
$ semaphore create 2
$ semaphore add -- docker build
$ semaphore add -- vagrant up
$ semaphore add -- ansible-playbook
$ semaphore wait --timeout=1m --notify
See more details here.
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