C++: 对双线程下载程序的封装和模拟

这是主程序,其中:

对线程,信号量进行了windows API的封装;

类似还可以完成对Mutex互斥量,临界区等的封装工作.

//main.cpp #include <iostream> #include <windows.h> #include "helper.h" using namespace std; /************************************************************************/ /* Thread */ /************************************************************************/ typedef DWORD (WINAPI *ThreadProc)(LPVOID lpParameter); class Thread { HANDLE hThread; DWORD dwThreadId; public: Thread(ThreadProc func) { dwThreadId = -1; hThread = NULL; hThread = CreateThread(NULL, 0, func, 0, CREATE_SUSPENDED, &dwThreadId); if(hThread == NULL) cout << "Create thread error: " << GetLastError() << endl; } DWORD getThreadId() { return dwThreadId; } HANDLE getThread() { return hThread; } void start() { ResumeThread(hThread); } void abort() { SuspendThread(hThread); } ~Thread() { CloseHandle(hThread); } }; /************************************************************************/ /* Semaphore */ /************************************************************************/ class Semaphore { HANDLE hSemaphore; public: Semaphore(int count, int nMaxCount) { hSemaphore = CreateSemaphore(NULL, count, nMaxCount, NULL); //无名信号量 } //comsume a signal: count-- void unSignal() { WaitForSingleObject(hSemaphore, INFINITE); } //raise a signal: count++ void signal() { if(!ReleaseSemaphore(hSemaphore, 1, NULL)) cout << "Release semaphore error: " << GetLastError() << endl; } ~Semaphore() { CloseHandle(hSemaphore); } }; /************************************************************************/ /* global defination */ /************************************************************************/ #define MAX_COUNT 100 int g_buffer[MAX_COUNT]; Semaphore g_seEmpty(MAX_COUNT, MAX_COUNT); Semaphore g_seFull(0, MAX_COUNT); int g_nInIndex = 0; int g_nOutIndex = 0; bool isDownloaded = false; /************************************************************************/ /* thread proc */ /************************************************************************/ DWORD WINAPI downloadProc(LPVOID lpParameter) { while (true) { g_seEmpty.unSignal(); isDownloaded = getBlockFromNet(g_buffer+g_nInIndex); g_nInIndex = (g_nInIndex+1)%MAX_COUNT; g_seFull.signal(); if(isDownloaded) break; } return 0L; } DWORD WINAPI writeProc(LPVOID lpParameter) { while (true) { g_seFull.unSignal(); writeBlockToDisk(g_buffer+g_nOutIndex); g_nOutIndex = (g_nOutIndex+1)%MAX_COUNT; g_seEmpty.signal(); if(isDownloaded && g_nInIndex == g_nOutIndex) break; } return 0L; } int main() { prepareData(); Thread thDownload(downloadProc); Thread thMove(writeProc); thDownload.start(); thMove.start(); HANDLE arrHandles[] = {thDownload.getThread(), thMove.getThread()}; WaitForMultipleObjects(sizeof(arrHandles)/sizeof(HANDLE), arrHandles, TRUE, INFINITE); destroyData(); return 0; }

 

这是辅助程序, 其中:

getBlockFromNet函数, 我是直接从内存中读取来模拟的;

writeBlockToDisk函数, 我是把上述数据写到文件中来实现的.

大致是可以模拟出来的.

//helper.h #include <fstream> #include <iostream> using namespace std; #define MAX_BUFFER 10000 int buffer[MAX_BUFFER]; int index = 0; ofstream ofs; void prepareData() { ofs.open("e://out.txt"); for (int i = 0; i < MAX_BUFFER; ++i) buffer[i] = i; } bool getBlockFromNet(int* buf) { *buf = buffer[index++]; if(index < MAX_BUFFER) return false; else return true; //取得最后一个buffer[MAX_BUFFER-1], 并返回true } void writeBlockToDisk(int* buf) { ofs << *buf << " "; } void destroyData() { ofs.close(); }