chromium/net/socket/udp_socket_global_limits.h

// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SOCKET_UDP_SOCKET_GLOBAL_LIMITS_H_
#define NET_SOCKET_UDP_SOCKET_GLOBAL_LIMITS_H_

#include "net/base/net_errors.h"
#include "net/base/net_export.h"

namespace net {

// Helper class for RAII-style management of the global count of "open UDP
// sockets" [1] in the process.
//
// Keeping OwnedUDPSocketCount alive increases the global socket counter by 1.
// When it goes out of scope - or is explicitly Reset() - the reference is
// returned to the global counter.
class NET_EXPORT OwnedUDPSocketCount { … };

// Attempts to increase the global "open UDP socket" [1] count.
//
// * On failure returns an OwnedUDPSocketCount that is |empty()|. This happens
//   if the global socket limit has been reached.
// * On success returns an OwnedUDPSocketCount that is |!empty()|. This
//   OwnedUDPSocketCount should be kept alive until the socket resource is
//   released.
//
// [1] For simplicity, an "open UDP socket" is defined as a net::UDPSocket that
// successfully called Open(), and has not yet called Close(). This is
// analogous to the number of open platform socket handles, and in practice
// should also be a good proxy for the number of consumed UDP ports.
[[nodiscard]] NET_EXPORT OwnedUDPSocketCount TryAcquireGlobalUDPSocketCount();

// Returns the current count of open UDP sockets (for testing only).
NET_EXPORT int GetGlobalUDPSocketCountForTesting();

}  // namespace net

#endif  // NET_SOCKET_UDP_SOCKET_GLOBAL_LIMITS_H_