链表式内存池.docVIP

Introduction What is memory pool? I think I must answer the question firstly, because it is important to beginner. In short, memory pool is a memory block which you got from system and use some unit of it to replace the system call malloc/free and new/delete. The advantage of the technology is reuse existing memory block so that reduce the times of system call. It`s a hard work to give the definition. If you still can`t understand the concept, please google it. Background Why to use memory pool? I have two reason:[1]To shorten the time that program allocate memory. Now I show an example to prove the technology have good efficiency: Collapse #include windows.h #include iostream.h class CTestClass { char m_chBuf[4096]; }; int main() { DWORD count = GetTickCount(); for(unsigned int i=0; i0x5fffff; i++) { CTestClass *p = new CTestClass; delete p; } cout Interval = GetTickCount()-count ms endl; return 0; } In my computer (Intel 3.0G Hz CPU / 512 MB of RAM / Win XP SP2 / VC6.0), the result is: Interval = 8735 ms When I use a simple memory pool, the code is following: Collapse #include windows.h #include iostream.h char buf[4100]; //Simple Memory Pool class CTestClass { char m_chBuf[4096]; public: void *operator new(unsigned int uiSize) { return (void *)buf; } void operator delete(void *p) { } }; int main() { DWORD count = GetTickCount(); for(unsigned int i=0; i0x5fffff; i++) { CTestClass *p = new CTestClass; //Didn`t use system new operator! delete p; } cout Interval = GetTickCount()-count ms endl; return 0; } In my computer, the result is: Interval = 391 ms As you see, the later is about twenty times faster than the former! What is cause? Because system call new/delete spent much time of former program! Of course, this is an extreme example! Anyway, we can know the value of memory pool