131 lines
3.7 KiB
C++
131 lines
3.7 KiB
C++
// synchlist.cc
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// Routines for synchronized access to a list.
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//
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// Implemented in "monitor"-style -- surround each procedure with a
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// lock acquire and release pair, using condition signal and wait for
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// synchronization.
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//
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// Copyright (c) 1992-1993 The Regents of the University of California.
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// All rights reserved. See copyright.h for copyright notice and limitation
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// of liability and disclaimer of warranty provisions.
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#include "copyright.h"
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#include "synchlist.h"
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//----------------------------------------------------------------------
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// SynchList<T>::SynchList
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// Allocate and initialize the data structures needed for a
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// synchronized list, empty to start with.
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// Elements can now be added to the list.
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//----------------------------------------------------------------------
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template <class T>
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SynchList<T>::SynchList()
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{
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list = new List<T>;
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lock = new Lock("list lock");
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listEmpty = new Condition("list empty cond");
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}
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//----------------------------------------------------------------------
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// SynchList<T>::~SynchList
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// De-allocate the data structures created for synchronizing a list.
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//----------------------------------------------------------------------
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template <class T>
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SynchList<T>::~SynchList()
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{
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delete listEmpty;
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delete lock;
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delete list;
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}
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//----------------------------------------------------------------------
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// SynchList<T>::Append
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// Append an "item" to the end of the list. Wake up anyone
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// waiting for an element to be appended.
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//
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// "item" is the thing to put on the list.
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//----------------------------------------------------------------------
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template <class T>
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void
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SynchList<T>::Append(T item)
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{
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lock->Acquire(); // enforce mutual exclusive access to the list
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list->Append(item);
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listEmpty->Signal(lock); // wake up a waiter, if any
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lock->Release();
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}
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//----------------------------------------------------------------------
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// SynchList<T>::RemoveFront
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// Remove an "item" from the beginning of the list. Wait if
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// the list is empty.
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// Returns:
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// The removed item.
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//----------------------------------------------------------------------
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template <class T>
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T
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SynchList<T>::RemoveFront()
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{
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T item;
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lock->Acquire(); // enforce mutual exclusion
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while (list->IsEmpty())
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listEmpty->Wait(lock); // wait until list isn't empty
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item = list->RemoveFront();
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lock->Release();
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return item;
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}
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//----------------------------------------------------------------------
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// SynchList<T>::Apply
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// Apply function to every item on a list.
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//
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// "func" -- the function to apply
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//----------------------------------------------------------------------
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template <class T>
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void
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SynchList<T>::Apply(void (*func)(T))
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{
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lock->Acquire(); // enforce mutual exclusion
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list->Apply(func);
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lock->Release();
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}
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//----------------------------------------------------------------------
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// SynchList<T>::SelfTest, SelfTestHelper
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// Test whether the SynchList implementation is working,
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// by having two threads ping-pong a value between them
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// using two synchronized lists.
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//----------------------------------------------------------------------
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template <class T>
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void
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SynchList<T>::SelfTestHelper (void* data)
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{
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SynchList<T>* _this = (SynchList<T>*)data;
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for (int i = 0; i < 10; i++) {
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_this->Append(_this->selfTestPing->RemoveFront());
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}
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}
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template <class T>
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void
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SynchList<T>::SelfTest(T val)
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{
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Thread *helper = new Thread("ping", 1);
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ASSERT(list->IsEmpty());
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selfTestPing = new SynchList<T>;
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helper->Fork(SynchList<T>::SelfTestHelper, this);
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for (int i = 0; i < 10; i++) {
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selfTestPing->Append(val);
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ASSERT(val == this->RemoveFront());
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}
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delete selfTestPing;
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}
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