小编use*_*858的帖子

对于C++中的默认参数,值是必须是常量还是另一个参数呢？

也就是说,以下工作可以吗？

RateLimiter(unsigned double rateInPermitsPerSecond, 
            unsigned int maxAccumulatedPermits = rateInPermitsPerSecond);

目前我收到一个错误:

RateLimiter.h:13:错误:'rateInPermitsPerSecond'未在此范围内声明

在Java中我们可以创建一个类

class Test {
    public synchronized void  fn1() {

    }

    public synchronized void  fn2() {

    }

    public synchronized void  fn3() {
        fn1(); // Calling another method
    }
}

在 C++ 中，如果我想模仿功能，一种方法是

class Test {
    private:
        mutex obj;
    public:
       void fn1(bool calledFromWithinClass = false) {
            if(calledFromWithinClass) 
                fn1Helper();
            else
                unique_lock<mutex> lock(obj);
                fn1Helper();
        }

       void fn2(bool calledFromWithinClass = false) {
            if(calledFromWithinClass) 
                fn2Helper();
            else
                unique_lock<mutex> lock(obj);
                fn2Helper();
        }

        void fn3(bool calledFromWithinClass = false) {
            if(calledFromWithinClass) 
                fn3Helper();
            else {
                unique_lock<mutex> lock(obj);
                fn3Helper();
            } 
        }
    private: …

当我尝试使用此配置启动 nginx 服务器时，出现错误

nginx: [emerg] no ssl_client_certificate for ssl_client_verify

我的配置看起来像

# HTTPS server
server {
    listen       4443;
    server_name  localhost;
    ssl                  on;
    ssl_certificate      /home/user/conf/ssl/server.pem;
    ssl_certificate_key  /home/user/conf/ssl/server.pem;
    ssl_protocols        TLSv1.2;

    ssl_verify_client optional;
    ssl_trusted_certificate /home/user/ssl/certs/certificate_bundle.pem;

    include conf.d/api_proxy.conf;
}

根据错误，我应该使用ssl_client_certificate指令，但根据文档，如果我不想将证书列表发送给客户端，我应该使用ssl_trusted_certificate.

http://nginx.org/en/docs/http/ngx_http_ssl_module.html#ssl_client_certificate

有人可以帮我弄清楚我错过了什么吗？

我试图使用shared_mutex在C++中使用读/写锁

typedef boost::shared_mutex Lock;
typedef boost::unique_lock< Lock >  WriteLock;
typedef boost::shared_lock< Lock >  ReadLock;

class Test {
    Lock lock;
    WriteLock writeLock;
    ReadLock readLock;

    Test() : writeLock(lock), readLock(lock) {}

    readFn1() {
        readLock.lock();
        /*
             Some Code
        */
        readLock.unlock();
    }

    readFn2() {
        readLock.lock();
        /*
             Some Code
        */
        readLock.unlock();
    }

    writeFn1() {
        writeLock.lock();
        /*
             Some Code
        */
        writeLock.unlock();
    }

    writeFn2() {
        writeLock.lock();
        /*
             Some Code
        */
        writeLock.unlock();
    }
}

代码似乎工作正常,但我有一些概念性的问题.

Q1.我已经看到了在http://en.cppreference.com/w/cpp/thread/shared_mutex/lock上使用unique_lock和shared_lock的建议,但我不明白为什么因为shared_mutex已经支持lock和lock_shared方法了？

Q2.这段代码是否有可能导致写入饥饿？如果是,那么我怎样才能避免饥饿呢？

Q3.有没有其他锁定类我可以尝试实现读写锁？

我有一个maven项目(链接),我想在其上运行代码覆盖.

我mvn test -Pcoverage jacoco:prepare-agent jacoco:report在主项目pom文件上运行命令,但不生成报告.相反,我得到一个警告说

[INFO] --- jacoco-maven-plugin:0.7.7.201606060606:report (post-test) @ pulsar-discovery-service ---
[INFO] Skipping JaCoCo execution due to missing execution data file.
[INFO] 
[INFO] --- jacoco-maven-plugin:0.7.7.201606060606:prepare-agent (default-cli) @ pulsar-discovery-service ---
[INFO] argLine set to -javaagent:/home/jai1/.m2/repository/org/jacoco/org.jacoco.agent/0.7.7.201606060606/org.jacoco.agent-0.7.7.201606060606-runtime.jar=destfile=/home/jai1/pulsar/pulsar-discovery-service/target/jacoco.exec
[INFO] 
[INFO] --- jacoco-maven-plugin:0.7.7.201606060606:report (default-cli) @ pulsar-discovery-service ---
[INFO] Skipping JaCoCo execution due to missing execution data file.

有人可以建议如何使用此pom文件生成代码覆盖率报告.我正在使用apache-maven-3.3.9和testNG.