Introduction to multi-thread programming

Introduction to multi-thread programming

<Pre name = "code" class = "cpp"> the first time I involved multi-threaded programming in C language, I got started with it. I used only java Runnable multi-threaded programming. This time, we can regard the screen as a resource which is shared by two threads,

# Include <iostream> # include <windows. h> using namespace std; dword winapi Fun (LPVOID lpParamter) {while (1) {cout <"Fun display! "<Endl; Sleep (1000); // 1000 indicates one second} int main () {HANDLE hThread = CreateThread (NULL, 0, Fun, NULL, 0, NULL ); closeHandle (hThread); while (1) {cout <"main display! "<Endl; Sleep (2000);} return 0;} // multiple consecutive blank lines or line breaks can be seen as a resource, this resource is shared by two threads. When the Fun function outputs the Fun display! Then, // The endl will be output (that is, clearing the buffer zone and wrapping it. here we don't need to understand what the buffer zone is), but the main function // gets the chance to run it, at this time, the Fun function gave the CPU to the main function before it could output a line feed, and then the main function // is directly in Fun display! And output main display!

// Solution 1: # include <iostream> # include <windows. h> using namespace std; dword winapi Fun (LPVOID lpParamter) {while (true) {cout <"Fun display! \ N "; Sleep (1000) ;}int main () {HANDLE hThread = CreateThread (NULL, 0, Fun, NULL, 0, NULL); CloseHandle (hThread ); while (true) {cout <"Main display! \ N "; Sleep (2000);} return 0 ;}

// Solution 2: Achieve alternate operation. This time, the problem is fundamentally solved, and multi-threaded shared resources are implemented. # include <iostream> # include <windows. h> using namespace std; HANDLE hMutex; dword winapi Fun (LPVOID lpParamter) {while (true) {WaitForSingleObject (hMutex, INFINITE); cout <"Fun display! "<Endl; Sleep (1000); ReleaseMutex (hMutex) ;}} int main () {HANDLE hThread = CreateThread (NULL, 0, Fun, NULL, 0, NULL ); hMutex = CreateMutex (NULL, FALSE, "aa"); cout /*

1 CreateThread function null, 0, fun, null, 0, null

HANDLE CreateThread (

LPSECURITY_ATTRIBUTESlpThreadAttributes, // thread Security Attribute

DWORDdwStackSize, // stack size

LPTHREAD_START_ROUTINElpStartAddress, // thread function

LPVOIDlpParameter, // thread Parameter

DWORDdwCreationFlags, // thread creation attribute

LPDWORDlpThreadId // thread ID

);

2 HANDLE (HANDLE): it is not a pointer, but a unique index of a process.

HANDLE is a concept in the Windows operating system. In a Windows program, there are various resources (such as Windows, icons, and cursors). The system allocates memory for these resources and returns the ID number indicating these resources, handle. Handle refers

A unique index of a core object in a process, not a pointer. Content identified by the handle due to address space restrictions

The process is invisible and can only be maintained by the operating system through the process handle list. Handle list: each process must create

Handle list, which points to various system resources, such as semaphores, threads, and files. All threads in the process can access

These resources.

3. dword winapi explanation: WINAPI is a call Convention. WINAPI is a _ stdcall, DWORD 32-bit system.

Dword winapi ThreadProc (

LPVOID lpParameter // thread data

);

4 Create an exclusive resource, parameter: null, false, "resource name"

HANDLE CreateMutex (

LPSECURITY_ATTRIBUTES lpMutexAttributes, // SD

BOOL bInitialOwner, // initial owner

Lptstr lpName // object name

);

The first parameter is not used. It can be set to NULL. The second parameter specifies whether the resource belongs to the process where it was created and the third parameter specifies the Resource Name.

Example: HANDLE hMutex = CreateMutex (NULL, TRUE, "screen ");

This statement creates a resource named screen and belongs to the process that created it.

5. release an exclusive resource:

BOOL ReleaseMutex (

HANDLE hMutex // handle to mutex

);

Once a process releases the resource, it no longer belongs to it. If you need to use the resource again, you need to apply for it again.



6. resource application function: the first parameter specifies the handle of the requested resource, and the second parameter is generally set to INFINITE.

DWORD WaitForSingleObject (

HANDLE hHandle, // handle to object

DWORD dwMilliseconds // time-out interval

);

It indicates that if the resource is not applied for, it will wait for the resource. If it is specified as 0, it indicates that the resource will be returned once it is not obtained. You can also specify how long it will be returned, in the unit of 1‰ seconds.

*/



Introduction to multi-thread programming
A small part of the multi-threaded programming knowledge C ++ does not have a special book to talk about ....
 
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First, C ++ must be ready.

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