HANDLE CreateEvent(
LPSECURITY_ATTRIBUTES lpEventAttributes,
BOOL bManualReset,
BOOL bInitialState,
LPCSTR lpName
);
bManualReset:TRUE，使用ResetEvent()手动重置为无信号状态；FALSE，当一个等待线程被释放时,自动重置状态为无信号状态。
bInitialState：指定事件对象的初始状态，当TRUE,初始状态为有信号状态；当FALSE,初始状态为无信号状态。
下面主要演示一下采用CreateEvent实现多线程。
例子很简单，主要测试CreateEvent中bManualReset:和bInitialState参数的取值在线程调用中信号状态的情况。
测试1：
bManualReset：TRUE
bInitialState：TRUE
CreateEvent(NULL, TRUE, TRUE, NULL); //使用手动重置为无信号状态，初始化时有信号状态
example.cpp
01.#include "iostream"
02.#include "windows.h"
03.using namespace std;
04.
05.DWORD WINAPI ThreadProc1(LPVOID lpParam);
06.DWORD WINAPI ThreadProc2(LPVOID lpParam);
07.HANDLE hEvent = NULL;
08.HANDLE hThread1 = NULL;
09.HANDLE hThread2 = NULL;
10.int main(int argc, char *args[])
11.{
12. <span style="color:#ff0000;">hEvent = CreateEvent(NULL, TRUE, TRUE, NULL)</span>; //使用手动重置为无信号状态，初始化时有信号状态
13. //hEvent = CreateEvent(NULL, FALSE, TRUE, NULL); //当一个等待线程被释放时，自动重置为无信号状态，初始是有信号状态
14. //if (SetEvent(hEvent))
15. //{
16. // cout << "setEvent 成功" <<endl;
17. //}
18. hThread1 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc1, NULL, 0,NULL);
19. Sleep(200);
20. hThread2 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc2, NULL, 0,NULL);
21. Sleep(200);
22. if ( NULL == hThread1)
23. {
24. cout <<"create thread fail!";
25. }
26. //DWORD dCount = ResumeThread(hThread);
27. //cout << LOWORD(dCount) << endl;
28. return 0;
29.}
30.DWORD WINAPI ThreadProc1(LPVOID lpParam)
31.{
32. cout <<"in thread1@!"<<endl;
33.
34. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
35.
36. if ( WAIT_OBJECT_0 == dReturn)
37. {
38. cout <<" thread1 signaled ! "<<endl;
39. }
40. cout <<"in thread1 --signal"<<endl;
41.
42. //SetEvent(hEvent);
43. return 0;
44.}
45.DWORD WINAPI ThreadProc2(LPVOID lpParam)
46.{
47. cout <<"in thread2@!"<<endl;
48.
49. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
50.
51. if ( WAIT_OBJECT_0 == dReturn)
52. {
53. cout <<"thread2 signaled ! "<<endl;
54. }
55. cout <<"in thread2--signal"<<endl;
56.
57. return 0;
58.}
执行结果：
从结果中看，执行完线程1又执行了线程2.
由于hEvent = CreateEvent(NULL, TRUE, TRUE, NULL)，使用手动重置为无信号状态，初始化时有信号状态
所以hEvent一直处于有信号状态，无论是线程1释放后，hEvent仍处于有信号状态，所以线程2正常执行了。
测试2：
bManualReset：FALSE
bInitialState：TRUE
hEvent = CreateEvent(NULL, FALSE, TRUE, NULL); //当一个等待线程被释放时，自动重置为无信号状态，初始是有信号状态
example2.cpp
01.#include "iostream"
02.#include "windows.h"
03.using namespace std;
04.
05.DWORD WINAPI ThreadProc1(LPVOID lpParam);
06.DWORD WINAPI ThreadProc2(LPVOID lpParam);
07.HANDLE hEvent = NULL;
08.HANDLE hThread1 = NULL;
09.HANDLE hThread2 = NULL;
10.int main(int argc, char *args[])
11.{
12. //hEvent = CreateEvent(NULL, TRUE, TRUE, NULL); //使用手动重置为无信号状态，初始化时有信号状态
13. <span style="color:#ff0000;">hEvent = CreateEvent(NULL, FALSE, TRUE, NULL); </span>//当一个等待线程被释放时，自动重置为无信号状态，初始是有信号状态
14. //if (SetEvent(hEvent))
15. //{
16. // cout << "setEvent 成功" <<endl;
17. //}
18. hThread1 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc1, NULL, 0,NULL);
19. Sleep(200);
20. hThread2 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc2, NULL, 0,NULL);
21. Sleep(200);
22. if ( NULL == hThread1)
23. {
24. cout <<"create thread fail!";
25. }
26. //DWORD dCount = ResumeThread(hThread);
27. //cout << LOWORD(dCount) << endl;
28. return 0;
29.}
30.DWORD WINAPI ThreadProc1(LPVOID lpParam)
31.{
32. cout <<"in thread1@!"<<endl;
33.
34. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
35.
36. if ( WAIT_OBJECT_0 == dReturn)
37. {
38. cout <<" thread1 signaled ! "<<endl;
39. }
40. cout <<"in thread1 --signal"<<endl;
41.
42. //SetEvent(hEvent);
43. return 0;
44.}
45.DWORD WINAPI ThreadProc2(LPVOID lpParam)
46.{
47. cout <<"in thread2@!"<<endl;
48.
49. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
50.
51. if ( WAIT_OBJECT_0 == dReturn)
52. {
53. cout <<"thread2 signaled ! "<<endl;
54. }
55. cout <<"in thread2--signal"<<endl;
56.
57. return 0;
58.}
执行结果：
从执行结果中分析，执行了线程1，线程2一直在等待，直到主线程结束。
由于hEvent = CreateEvent(NULL, FALSE, TRUE, NULL)，当一个等待线程被释放时，自动重置为无信号状态，初始是有信号状态
初始执行线程1的时候，hEvent是有信号的，所以线程1正常执行；又由于bManualReset=FALSE，所以执行完线程1后，hEvent自动重置为无信号状态，所以在线程2中，
WaitForSingleObject(hEvent,INFINITE);
WaitForSingleObject(hEvent,INFINITE);函数一直在等待hEvent变为有信号状态，但是当主线程执行完，还没等待到，线程2程序一直没有走下去。
测试3：
bManualReset：TRUE
bInitialState：FALSE
hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);//使用手动重置为无信号状态，初始化时为无信号状态
example3.cpp
01.#include "iostream"
02.#include "windows.h"
03.using namespace std;
04.
05.DWORD WINAPI ThreadProc1(LPVOID lpParam);
06.DWORD WINAPI ThreadProc2(LPVOID lpParam);
07.HANDLE hEvent = NULL;
08.HANDLE hThread1 = NULL;
09.HANDLE hThread2 = NULL;
10.int main(int argc, char *args[])
11.{
12. //hEvent = CreateEvent(NULL, TRUE, TRUE, NULL); //使用手动重置为无信号状态，初始化时有信号状态
13. //hEvent = CreateEvent(NULL, FALSE, TRUE, NULL); //当一个等待线程被释放时，自动重置为无信号状态，初始是有信号状态
14. <span style="color:#ff0000;">hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);//使用手动重置为无信号状态，初始化时为无信号状态</span>
15. //if (SetEvent(hEvent))
16. //{
17. // cout << "setEvent 成功" <<endl;
18. //}
19. hThread1 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc1, NULL, 0,NULL);
20. Sleep(200);
21. hThread2 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc2, NULL, 0,NULL);
22. Sleep(200);
23. if ( NULL == hThread1)
24. {
25. cout <<"create thread fail!";
26. }
27. //DWORD dCount = ResumeThread(hThread);
28. //cout << LOWORD(dCount) << endl;
29. return 0;
30.}
31.DWORD WINAPI ThreadProc1(LPVOID lpParam)
32.{
33. cout <<"in thread1@!"<<endl;
34.
35. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
36.
37. if ( WAIT_OBJECT_0 == dReturn)
38. {
39. cout <<" thread1 signaled ! "<<endl;
40. }
41. cout <<"in thread1 --signal"<<endl;
42.
43. //SetEvent(hEvent);
44. return 0;
45.}
46.DWORD WINAPI ThreadProc2(LPVOID lpParam)
47.{
48. cout <<"in thread2@!"<<endl;
49.
50. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
51.
52. if ( WAIT_OBJECT_0 == dReturn)
53. {
54. cout <<"thread2 signaled ! "<<endl;
55. }
56. cout <<"in thread2--signal"<<endl;
57.
58. return 0;
59.}
执行结果，可想而知，只能输出：
in thread1@!
in thread1@![cpp] view plaincopyprint?in thread2@!
in thread2@!因为初始为无信号状态，所以hEvent一直处于无信号状态，因此这两个线程一直在等待，直到主线程结束。
修改：放开例子中的注释部分：
if (SetEvent(hEvent))//设置信号为有信号状态
{
cout << "setEvent 成功" <<endl;
}
执行结果：
可见，线程1和线程2都执行了。
因为调用SetEvent，事件变为有信号状态，线程1执行；又由于线程1释放后，hEvent仍旧处于有信号状态，所以线程2也执行了。
再修改:在线程1中，添加ResetEvent(hEvent)（手动设置事件为无信号状态），则线程2不会执行。
测试4：
bManualReset：FALSE
bInitialState：FALSE
hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);//线程释放后自动重置为无信号状态，初始化时为无信号状态
example4.cpp
01.#include "iostream"
02.#include "windows.h"
03.using namespace std;
04.
05.DWORD WINAPI ThreadProc1(LPVOID lpParam);
06.DWORD WINAPI ThreadProc2(LPVOID lpParam);
07.HANDLE hEvent = NULL;
08.HANDLE hThread1 = NULL;
09.HANDLE hThread2 = NULL;
10.int main(int argc, char *args[])
11.{
12. //hEvent = CreateEvent(NULL, TRUE, TRUE, NULL); //使用手动重置为无信号状态，初始化时有信号状态
13. //hEvent = CreateEvent(NULL, FALSE, TRUE, NULL); //当一个等待线程被释放时，自动重置为无信号状态，初始是有信号状态
14. //hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);//使用手动重置为无信号状态，初始化时为无信号状态
15. hEvent = CreateEvent(NULL, FALSE, FALSE, NULL);//使用手动重置为无信号状态，初始化时为无信号状态
16. if (SetEvent(hEvent))
17. {
18. cout << "setEvent 成功" <<endl;
19. }
20. hThread1 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc1, NULL, 0,NULL);
21. Sleep(200);
22. hThread2 = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)ThreadProc2, NULL, 0,NULL);
23. Sleep(200);
24. if ( NULL == hThread1)
25. {
26. cout <<"create thread fail!";
27. }
28. //DWORD dCount = ResumeThread(hThread);
29. //cout << LOWORD(dCount) << endl;
30. return 0;
31.}
32.DWORD WINAPI ThreadProc1(LPVOID lpParam)
33.{
34. cout <<"in thread1@!"<<endl;
35.
36. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
37.
38. if ( WAIT_OBJECT_0 == dReturn)
39. {
40. cout <<" thread1 signaled ! "<<endl;
41. }
42. cout <<"in thread1 --signal"<<endl;
43.
44. //SetEvent(hEvent);
45. return 0;
46.}
47.DWORD WINAPI ThreadProc2(LPVOID lpParam)
48.{
49. cout <<"in thread2@!"<<endl;
50.
51. DWORD dReturn = WaitForSingleObject(hEvent,INFINITE);
52.
53. if ( WAIT_OBJECT_0 == dReturn)
54. {
55. cout <<"thread2 signaled ! "<<endl;
56. }
57. cout <<"in thread2--signal"<<endl;
58.
59. return 0;
60.}
执行结果：
由于调用SetEvent，hEvent为有信号状态，线程1正常执行，又由于调用完线程1后，hEvent自动重置为无信号状态，所以线程2只能在等待，直到主线程退出。
修改：线程1中的SetEvent(hEvent);的注释去掉，再运行，则线程1和线程2 都会执行。
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