修复执行std::function时同时可能覆写导致的bug

Author: xia-chu

src/Network/BufferSock.h

@@ -53,7 +53,7 @@ class BufferSock : public Buffer {
 class BufferList : public noncopyable {
 public:
     using Ptr = std::shared_ptr<BufferList>;
-    using SendResult = std::function<void(const Buffer::Ptr &buffer, bool send_success)>;
+    using SendResult = toolkit::function_safe<void(const Buffer::Ptr &buffer, bool send_success)>;
 
     BufferList() = default;
     virtual ~BufferList() = default;

src/Network/Socket.h

@@ -315,20 +315,20 @@ class Socket : public std::enable_shared_from_this<Socket>, public noncopyable,
     //接收数据回调  [AUTO-TRANSLATED:e3b7ff16]
     //Receive data callback
     using onReadCB = std::function<void(Buffer::Ptr &buf, struct sockaddr *addr, int addr_len)>;
-    using onMultiReadCB = std::function<void(Buffer::Ptr *buf, struct sockaddr_storage *addr, size_t count)>;
+    using onMultiReadCB = toolkit::function_safe<void(Buffer::Ptr *buf, struct sockaddr_storage *addr, size_t count)>;
 
     //发生错误回调  [AUTO-TRANSLATED:d6897b99]
     //Error callback
-    using onErrCB = std::function<void(const SockException &err)>;
+    using onErrCB = toolkit::function_safe<void(const SockException &err)>;
     //tcp监听接收到连接请求  [AUTO-TRANSLATED:c4e1b206]
     //TCP listen receives a connection request
-    using onAcceptCB = std::function<void(Socket::Ptr &sock, std::shared_ptr<void> &complete)>;
+    using onAcceptCB = toolkit::function_safe<void(Socket::Ptr &sock, std::shared_ptr<void> &complete)>;
     //socket发送缓存清空事件，返回true代表下次继续监听该事件，否则停止  [AUTO-TRANSLATED:2dd1c036]
     //Socket send buffer is cleared event, returns true to continue listening for the event next time, otherwise stops
-    using onFlush = std::function<bool()>;
+    using onFlush = toolkit::function_safe<bool()>;
     //在接收到连接请求前，拦截Socket默认生成方式  [AUTO-TRANSLATED:2f07f268]
     //Intercept the default generation method of the Socket before receiving a connection request
-    using onCreateSocket = std::function<Ptr(const EventPoller::Ptr &poller)>;
+    using onCreateSocket = toolkit::function_safe<Ptr(const EventPoller::Ptr &poller)>;
     //发送buffer成功与否回调  [AUTO-TRANSLATED:4db5efb8]
     //Send buffer success or failure callback
     using onSendResult = BufferList::SendResult;

src/Util/util.h

@@ -21,6 +21,7 @@
 #include <atomic>
 #include <unordered_map>
 #include "function_traits.h"
+#include "onceToken.h"
 #if defined(_WIN32)
 #undef FD_SETSIZE
 //修改默认64为1024路  [AUTO-TRANSLATED:90567e14]
@@ -504,6 +505,81 @@ class AnyStorage : public std::unordered_map<std::string, Any> {
     using Ptr = std::shared_ptr<AnyStorage>;
 };
 
+template <class R, class... ArgTypes>
+class function_safe;
+
+template <typename R, typename... ArgTypes>
+class function_safe<R(ArgTypes...)> {
+public:
+    using func = std::function<R(ArgTypes...)>;
+    using this_type = function_safe<R(ArgTypes...)>;
+
+    template <class F>
+    using enable_if_not_this = typename std::enable_if<!std::is_same<this_type, typename std::decay<F>::type>::value, typename std::decay<F>::type>::type;
+
+    R operator()(ArgTypes... args) const {
+        onceToken token([&]() { _doing = true; checkUpdate(); }, [&]() { checkUpdate(); _doing = false; });
+        if (!_impl) {
+            throw std::invalid_argument("try to invoke a empty functional");
+        }
+        return _impl(std::forward<ArgTypes>(args)...);
+    }
+
+    function_safe(std::nullptr_t) {
+        update(func{});
+    }
+
+    function_safe &operator=(std::nullptr_t) {
+        update(func{});
+        return *this;
+    }
+
+    template <typename F, typename = enable_if_not_this<F>>
+    function_safe(F &&f) {
+        update(func { std::forward<F>(f) });
+    }
+
+    template <typename F, typename = enable_if_not_this<F>>
+    this_type &operator=(F &&f) {
+        update(func { std::forward<F>(f) });
+        return *this;
+    }
+
+    function_safe() = default;
+    function_safe(this_type &&) = default;
+    function_safe(const this_type &) = default;
+    this_type &operator=(this_type &&) = default;
+    this_type &operator=(const this_type &) = default;
+
+    operator bool() const { return _update ? (bool)_tmp : (bool)_impl; }
+
+private:
+    void checkUpdate() const {
+        if (_update) {
+            _update = false;
+            _impl = std::move(_tmp);
+        }
+    }
+    void update(func in) {
+        if (!_doing) {
+            // 没在执行中，那么立即覆写
+            _impl = std::move(in);
+            _tmp = nullptr;
+            _update = false;
+        } else {
+            // 正在执行中，延后覆写
+            _tmp = std::move(in);
+            _update = true;
+        }
+    }
+
+private:
+    mutable bool _update = false;
+    mutable bool _doing = false;
+    mutable func _tmp;
+    mutable func _impl;
+};
+
 }  // namespace toolkit
 
 #ifdef __cplusplus