| // Copyright 2020 The Chromium Authors. All rights reserved. |
| // 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 "base/compiler_specific.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 { |
| public: |
| // The default constructor builds an empty OwnedUDPSocketCount (does not own a |
| // count). |
| OwnedUDPSocketCount(); |
| |
| // Any count held by OwnedUDPSocketCount is transferred when moving. |
| OwnedUDPSocketCount(OwnedUDPSocketCount&&); |
| OwnedUDPSocketCount& operator=(OwnedUDPSocketCount&&); |
| |
| // This is a move-only type. |
| OwnedUDPSocketCount(const OwnedUDPSocketCount&) = delete; |
| OwnedUDPSocketCount& operator=(const OwnedUDPSocketCount&) = delete; |
| |
| ~OwnedUDPSocketCount(); |
| |
| // Returns false if this instance "owns" a socket count. In |
| // other words, when |empty()|, destruction of |this| will |
| // not change the global socket count. |
| bool empty() const { return empty_; } |
| |
| // Resets |this| to an empty state (|empty()| becomes true after |
| // calling this). If |this| was previously |!empty()|, the global |
| // socket count will be decremented. |
| void Reset(); |
| |
| private: |
| // Only TryAcquireGlobalUDPSocketCount() is allowed to construct a non-empty |
| // OwnedUDPSocketCount. |
| friend NET_EXPORT OwnedUDPSocketCount TryAcquireGlobalUDPSocketCount(); |
| explicit OwnedUDPSocketCount(bool empty); |
| |
| bool empty_; |
| }; |
| |
| // 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. |
| NET_EXPORT OwnedUDPSocketCount TryAcquireGlobalUDPSocketCount() |
| WARN_UNUSED_RESULT; |
| |
| // 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_ |