package api import ( "net/http" "time" "github.com/TrueCloudLab/frostfs-s3-gw/api/errors" ) type ( // MaxClients provides HTTP handler wrapper with the client limit. MaxClients interface { Handle(http.HandlerFunc) http.HandlerFunc } maxClients struct { pool chan struct{} timeout time.Duration } ) const defaultRequestDeadline = time.Second * 30 // NewMaxClientsMiddleware returns MaxClients interface with handler wrapper based on // the provided count and the timeout limits. func NewMaxClientsMiddleware(count int, timeout time.Duration) MaxClients { if timeout <= 0 { timeout = defaultRequestDeadline } return &maxClients{ pool: make(chan struct{}, count), timeout: timeout, } } // Handler wraps HTTP handler function with logic limiting access to it. func (m *maxClients) Handle(f http.HandlerFunc) http.HandlerFunc { return func(w http.ResponseWriter, r *http.Request) { if m.pool == nil { f.ServeHTTP(w, r) return } deadline := time.NewTimer(m.timeout) defer deadline.Stop() select { case m.pool <- struct{}{}: defer func() { <-m.pool }() f.ServeHTTP(w, r) case <-deadline.C: // Send a http timeout message WriteErrorResponse(w, GetReqInfo(r.Context()), errors.GetAPIError(errors.ErrOperationTimedOut)) return case <-r.Context().Done(): return } } }