xref: /recipes/thread/Thread.cc

// excerpts from http://code.google.com/p/muduo/
//
// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (giantchen at gmail dot com)

#include "Thread.h"

#include <boost/weak_ptr.hpp>

#include <unistd.h>
#include <sys/syscall.h>
#include <sys/types.h>

#if __FreeBSD__
#include <pthread_np.h>
#else
#include <sys/prctl.h>
#include <linux/unistd.h>
#endif

namespace muduo
{
namespace CurrentThread
{
  __thread const char* t_threadName = "unnamedThread";
}
}

namespace
{
__thread pid_t t_cachedTid = 0;

#if __FreeBSD__
pid_t gettid()
{
  return pthread_getthreadid_np();
}
#else
#if !__GLIBC_PREREQ(2,30)
pid_t gettid()
{
  return static_cast<pid_t>(::syscall(SYS_gettid));
}
#endif
#endif

void afterFork()
{
  t_cachedTid = gettid();
  muduo::CurrentThread::t_threadName = "main";
  // no need to call pthread_atfork(NULL, NULL, &afterFork);
}

class ThreadNameInitializer
{
 public:
  ThreadNameInitializer()
  {
    muduo::CurrentThread::t_threadName = "main";
    pthread_atfork(NULL, NULL, &afterFork);
  }
};

ThreadNameInitializer init;

struct ThreadData
{
  typedef muduo::Thread::ThreadFunc ThreadFunc;
  ThreadFunc func_;
  std::string name_;
  boost::weak_ptr<pid_t> wkTid_;

  ThreadData(const ThreadFunc& func,
             const std::string& name,
             const boost::shared_ptr<pid_t>& tid)
    : func_(func),
      name_(name),
      wkTid_(tid)
  { }

  void runInThread()
  {
    pid_t tid = muduo::CurrentThread::tid();
    boost::shared_ptr<pid_t> ptid = wkTid_.lock();

    if (ptid)
    {
      *ptid = tid;
      ptid.reset();
    }

    if (!name_.empty())
      muduo::CurrentThread::t_threadName =  name_.c_str();
#if __FreeBSD__
    // setname_np() costs as much as creating a thread on FreeBSD 13.
    pthread_setname_np(pthread_self(), muduo::CurrentThread::t_threadName);
#else
    ::prctl(PR_SET_NAME, muduo::CurrentThread::t_threadName);
#endif
    func_(); // FIXME: surround with try-catch, see muduo
    muduo::CurrentThread::t_threadName = "finished";
  }
};

void* startThread(void* obj)
{
  ThreadData* data = static_cast<ThreadData*>(obj);
  data->runInThread();
  delete data;
  return NULL;
}

}

using namespace muduo;

pid_t CurrentThread::tid()
{
  if (t_cachedTid == 0)
  {
    t_cachedTid = gettid();
  }
  return t_cachedTid;
}

const char* CurrentThread::name()
{
  return t_threadName;
}

bool CurrentThread::isMainThread()
{
  return tid() == ::getpid();
}

AtomicInt32 Thread::numCreated_;

Thread::Thread(const ThreadFunc& func, const std::string& n)
  : started_(false),
    joined_(false),
    pthreadId_(0),
    tid_(new pid_t(0)),
    func_(func),
    name_(n)
{
  numCreated_.increment();
}

Thread::~Thread()
{
  if (started_ && !joined_)
  {
    pthread_detach(pthreadId_);
  }
}

void Thread::start()
{
  assert(!started_);
  started_ = true;

  ThreadData* data = new ThreadData(func_, name_, tid_);
  if (pthread_create(&pthreadId_, NULL, &startThread, data))
  {
    started_ = false;
    delete data;
    abort();
  }
}

void Thread::join()
{
  assert(started_);
  assert(!joined_);
  joined_ = true;
  pthread_join(pthreadId_, NULL);
}