Merge branch 'master' into develop

Author: mutouyun

README.md

@@ -3,6 +3,7 @@
 [![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](https://github.com/mutouyun/cpp-ipc/blob/master/LICENSE) 
 [![Build Status](https://github.com/mutouyun/cpp-ipc/actions/workflows/c-cpp.yml/badge.svg)](https://github.com/mutouyun/cpp-ipc/actions)
 [![Build status](https://ci.appveyor.com/api/projects/status/github/mutouyun/cpp-ipc?branch=master&svg=true)](https://ci.appveyor.com/project/mutouyun/cpp-ipc)
+[![Vcpkg package](https://img.shields.io/badge/Vcpkg-package-blueviolet)](https://github.com/microsoft/vcpkg/tree/master/ports/cpp-ipc)
 
 A high-performance inter-process communication using shared memory on Linux/Windows.  
 使用共享内存的跨平台（Linux/Windows，x86/x64/ARM）高性能IPC通讯库。
@@ -14,6 +15,7 @@ A high-performance inter-process communication using shared memory on Linux/Wind
  * `ipc::route`支持单写多读，`ipc::channel`支持多写多读【**注意：目前同一条通道最多支持32个receiver，sender无限制**】
  * 默认采用广播模式收发数据，支持用户任意选择读写方案
  * 不会长时间忙等（重试一定次数后会使用信号量进行等待），支持超时
+ * 支持[Vcpkg](https://github.com/microsoft/vcpkg/blob/master/README_zh_CN.md)方式安装，如`vcpkg install cpp-ipc`
 
 ## Usage
 

src/libipc/queue.h

@@ -144,7 +144,7 @@ class queue_base : public queue_conn {
     }
 
     std::size_t conn_count() const noexcept {
-        return (elems_ == nullptr) ? invalid_value : elems_->conn_count();
+        return (elems_ == nullptr) ? static_cast<std::size_t>(invalid_value) : elems_->conn_count();
     }
 
     bool valid() const noexcept {