lock::acquire

取得鎖定物件，並選擇性地等待一定保護不會鎖定，一個經過指定的時間的或。

void acquire();
void acquire(
   int _timeout
);
void acquire(
   System::TimeSpan _timeout
);

參數

• _timeout
  逾時值 (以毫秒為單位) 或 TimeSpan。

例外狀況

如果鎖定作業不在逾時之前，就會擲回 ApplicationException 。

備註

如果沒有提供逾時值，預設逾時是 Infinite。

如果鎖定已取得，這個函式不會執行任何動作。

範例

這個範例使用類別的單一執行個體跨多個執行緒的。類別會使用自己的鎖定確保對其內部資料的存取權為每個執行緒是一致的。主應用程式執行緒使用類別的同一個執行個體上具有鎖定定期檢查任何背景工作執行緒是否仍存在，而且會結束，直到所有背景工作執行緒完成其工作。

// msl_lock_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
         }
      }
   }
}

需求

標頭檔 <msclr \ lock.h>

命名空間 msclr

請參閱

參考

lock::try_acquire

其他資源

lock 成員