027ada452e
* Switch mongodb driver to mongo-driver * Tidy mod * Make writeConcern private * Implement review feedback * Add retry functionality * Added backoff time * go mod vendor * Fix failing test * goimport
58 lines
1.2 KiB
Go
58 lines
1.2 KiB
Go
// Copyright (C) MongoDB, Inc. 2017-present.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License"); you may
|
|
// not use this file except in compliance with the License. You may obtain
|
|
// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
package internal
|
|
|
|
import (
|
|
"context"
|
|
"errors"
|
|
)
|
|
|
|
// NewSemaphore creates a new semaphore.
|
|
func NewSemaphore(slots uint64) *Semaphore {
|
|
ch := make(chan struct{}, slots)
|
|
for i := uint64(0); i < slots; i++ {
|
|
ch <- struct{}{}
|
|
}
|
|
|
|
return &Semaphore{
|
|
permits: ch,
|
|
}
|
|
}
|
|
|
|
// Semaphore is a synchronization primitive that controls access
|
|
// to a common resource.
|
|
type Semaphore struct {
|
|
permits chan struct{}
|
|
}
|
|
|
|
// Len gets the number of permits available.
|
|
func (s *Semaphore) Len() uint64 {
|
|
return uint64(len(s.permits))
|
|
}
|
|
|
|
// Wait waits until a resource is available or until the context
|
|
// is done.
|
|
func (s *Semaphore) Wait(ctx context.Context) error {
|
|
select {
|
|
case <-s.permits:
|
|
return nil
|
|
case <-ctx.Done():
|
|
return ctx.Err()
|
|
}
|
|
}
|
|
|
|
// Release releases a resource back into the pool.
|
|
func (s *Semaphore) Release() error {
|
|
select {
|
|
case s.permits <- struct{}{}:
|
|
default:
|
|
return errors.New("internal.Semaphore.Release: attempt to release more resources than are available")
|
|
}
|
|
|
|
return nil
|
|
}
|