lock::try_acquire

捕获对象的锁，等待一个指定时间和返回 bool 报告购买的成功而不是引发异常。

bool try_acquire(
   int _timeout_ms
);
bool try_acquire(
   System::TimeSpan _timeout
);

参数

• _timeout
  超时值以毫秒或作为 TimeSpan。

返回值

true ，如果锁获取，否则 false 。

备注

如果锁已获得的，此功能不执行任何操作。

示例

此示例使用类的一个实例在多个线程中。类使用在自身的锁确保对其内部数据的访问为每个线程都是一致的。主应用程序线程使用类的同一个实例的锁定期检查任何辅助线程是否仍然存在，并会退出，直到所有辅助线程完成他们的任务。

// msl_lock_try_acquire.cpp
// compile with: /clr
#include <msclr/lock.h>

using namespace System;
using namespace System::Threading;
using namespace msclr;

ref class CounterClass {
private:
   int Counter;   

public:
   property int ThreadCount;

   // function called by multiple threads, use lock to keep Counter consistent
   // for each thread
   void UseCounter() {
      try {
         lock l(this); // wait infinitely

         Console::WriteLine("In thread {0}, Counter = {1}", Thread::CurrentThread->ManagedThreadId, 
            Counter);

         for (int i = 0; i < 10; i++) {
            Counter++;
            Thread::Sleep(10);
         }
         
         Console::WriteLine("In thread {0}, Counter = {1}", Thread::CurrentThread->ManagedThreadId, 
            Counter);

         Counter = 0;
         // lock is automatically released when it goes out of scope and its destructor is called
      }
      catch (...) {
         Console::WriteLine("Couldn't acquire lock!");
      }

      ThreadCount--;
   }
};

int main() {
   // create a few threads to contend for access to the shared data
   CounterClass^ cc = gcnew CounterClass;
   array<Thread^>^ tarr = gcnew array<Thread^>(5);
   ThreadStart^ startDelegate = gcnew ThreadStart(cc, &CounterClass::UseCounter);
   for (int i = 0; i < tarr->Length; i++) {
      tarr[i] = gcnew Thread(startDelegate);
      cc->ThreadCount++;
      tarr[i]->Start();
   }

   // keep our main thread alive until all worker threads have completed
   lock l(cc, lock_later); // don't lock now, just create the object
   while (true) {
      if (l.try_acquire(50)) { // try to acquire lock, don't throw an exception if can't
         if (0 == cc->ThreadCount) {
            Console::WriteLine("All threads completed.");
            break; // all threads are gone, exit while
         }
         else {
            Console::WriteLine("{0} threads exist, continue waiting...", cc->ThreadCount);
            l.release(); // some threads exist, let them do their work
         }
      }
   }
}

要求

头文件 <msclr \ lock.h>

命名空间 msclr

请参见

参考

lock::acquire

其他资源

锁定成员