Hardwired's Thread Safe Single Link List Template






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Feb 26, 2005
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This article explains how to use CLinkedListSingle template class. This template is a thread safe implementation of single link list.
Introduction
Most of you know how to implement a Single Linked List. Not so many know how to make a template out of it. Even less know how to make it thread safe. Of course, not all application need Thread Safe Single Link List. Application like notepad, calculator or ping. Hmmm... still...
Anyway, lists and thread safe, are two things that go hand in hand when developing... any kind of application. By making any list thread safe you avoid a lot of problems. Problems which are not easy to trace using a debugger.
...and if all this comes as a template... even better.
All this being said, let's get to the point.
Using the code
First add everything that's in the pack to your project: LinkedListSingle.h
,
LinkedListSingle.cpp
, NamedCriticalSection.h
, NamedCriticalSection.cpp
,
SpinLock.h
, SpinLock.cpp
, DebugTrace.h
and DebugTrace.cpp
.
Second, include this where you need to declare a new list:
#include "LinkedListSingle.h" #include "LinkedListSingle.cpp" // you need this too, or the code for the list will not be generated!!!
Once you did all this, declare a new list, like this:
// // somewhere in your application: // CLinkedListSingle<int, sinzeof(int)> IntegerList;
The template can be used with anything... so, let's complicate the things a bit. Let's say we have this class:
// // some class // class SomeClass { double DVar; // a double private data member public: char szString[ 32 ]; // a string public data member SomeClass(): DVar( 0 ) { memset( szString, 0, 32 ); }; ~SomeClass(){}; void Increase( void ){ DVar++; }; }
Now, you want a list of SomeClass
elements. You declare it like this:
// // somewhere in your application: // CLinkedListSingle<SomeClass, sinzeof(SomeClass)> SomeClassList;
CLinkedListSingle
It's not a complex class... once you get to know it:).
template <class T, int i> class CLinkedListSingle { CDebugTrace Trace; // used for debugging USHORT Size; // size of list public: CLinkedListSingleNode< T, i > *pHead; // head of list CNamedCriticalSection Section; // critical section object used to lock the list // this way using the list in a thread safe manner CLinkedListSingle(); ~CLinkedListSingle(); bool Initialize(); // initialize the list bool Free(); // release all elements of the list bool Add(T&); // add new element to the head of list bool Remove(T&); // remove element - by content bool Remove(USHORT); // remove element - by position bool Insert(USHORT, T&); // insert element in list USHORT GetSize(void); // get the size of list };
Normally this should not interest you. This class is made to just "set it and use it".
One more thing. If you ever need to directly access the elements of the list - let's say you need to "walk" through all the elements and do something - remember to do this:
// // somewhere in your application: // CLinkedListSingle<SomeClass, sinzeof(SomeClass)> SomeClassList;
// // somewhere else in your application (different thread for example) // CSpinLock Spin( &(SomeClass.Section), "NoWhere" ); if( Spin.Lock() ) { // // direct access over list and elements data // ... Spin.Unlock(); }
Points of Interest
Anything involving linked lists. This article refers only to Single Link List, but should not be hard for you to create a Double Link List out of it. I hope soon I will be able to post a new article about it.
History
version 1.0 - 27-february-2005 - So, now it's history!:)