nachos02线程与同步.doc

实验二　线程与同步 实验目的 实现Nachos的同步机制：锁和条件变量，并利用这些同步机制实现一些工具类。 实验内容 （1）实现锁机制和条件变量 （2）实现一个线程安全的表结构 （3）实现一个大小受限的缓冲区 实验步骤 3.1实现锁机制和条件变量 用Thread::Sleep实现锁机制和条件变量 对synch.h做一下修改后保存为synch-sleep.h： class Lock { public: Lock(char* debugName,int initialValue); // initialize lock to be FREE ~Lock(); // deallocate lock char* getName() { return name; } // debugging assist void Acquire(); // these are the only operations on a lock void Release(); // they are both *atomic* bool isHeldByCurrentThread(); // true if the current thread // holds this lock. Useful for // checking in Release, and in // Condition variable ops below. private: char* name; int value; List *queue; Thread *current; // for debugging // plus some other stuff youll need to define }; class Condition { public: Condition(char* debugName); // initialize condition to // no one waiting ~Condition(); // deallocate the condition char* getName() { return (name); } void Wait(Lock *conditionLock); // these are the 3 operations on // condition variables; releasing the // lock and going to sleep are // *atomic* in Wait() void Signal(Lock *conditionLock); // conditionLock must be held by void Broadcast(Lock *conditionLock);// the currentThread for all of // these operations private: char* name; List *queue; // plus some other stuff youll need to define }; 对synch.cc进行修改，实现其中未实现的函数，保存为synch-sleep.cc： Lock::Lock(char* debugName,int initialValue) { name = debugName; value = initialValue; queue = new List; } Lock::~Lock() { delete queue; } void Lock::Acquire() { IntStatus oldLevel = interrupt-SetLevel(IntOff); while (value == 0) { // semaphore not available queue-Append((void *)currentThread); currentThread-Sleep(); } value--; current=currentThread; (void) interrupt-SetLevel(oldLevel); } void Lock::Release() { Thread *thread; ASSERT(isHeldByCurrentThread()==tru