/*
 * TaskQueS.c
 *
 * Sample code for "Multithreading Applications in Win32"
 * This is from Chapter 3, Listing 3-2
 *
 * Call ThreadFunc NUM_TASKS times, using
 * no more than THREAD_POOL_SIZE threads.
 * This version uses WaitForSingleObject,
 * which gives a very suboptimal solution.
 *
 * Build command: cl /MD TaskQueS.c
 */

#define WIN32_LEAN_AND_MEAN
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include "MtVerify.h"

DWORD WINAPI ThreadFunc(LPVOID);

#define THREAD_POOL_SIZE 3
#define MAX_THREAD_INDEX THREAD_POOL_SIZE-1
#define NUM_TASKS 6

int main()
{
    HANDLE  hThrds[THREAD_POOL_SIZE];
    int     slot = 0;
    DWORD   threadId;
    int     i;
    DWORD   exitCode;

    /*           i=   1 2 3 4 5 6 7 8 9
     * Start Thread   X X X X X X 
     * Wait on thread       X X X X X X
     */
    for (i=1; i<=NUM_TASKS; i++)
    {
        if (i > THREAD_POOL_SIZE)
        {
            WaitForSingleObject(hThrds[slot], INFINITE);
            MTVERIFY( GetExitCodeThread(hThrds[slot], &exitCode) );
            printf("Slot %d terminated\n", exitCode );
            MTVERIFY( CloseHandle(hThrds[slot]) );
        }
        MTVERIFY( hThrds[slot] = CreateThread(NULL,
            0,
            ThreadFunc,
            (LPVOID)slot,
            0,
            &threadId ) );
        printf("Launched thread #%d (slot %d)\n", i, slot);
        if (++slot > MAX_THREAD_INDEX)
            slot = 0;
    }
    for (slot=0; slot<THREAD_POOL_SIZE; slot++)
    {
        WaitForSingleObject(hThrds[slot], INFINITE);
        MTVERIFY( CloseHandle(hThrds[slot]) );
    }
    printf("All slots terminated\n");

    return EXIT_SUCCESS;
}

/*
 * This function just calls Sleep for
 * a random amount of time, thereby
 * simulating some tasks that takes time.
 *
 * The param "n" is the index into
 * the handle array, kept for informational
 * purposes.
 */
DWORD WINAPI ThreadFunc(LPVOID n)
{
    srand( GetTickCount() );

    Sleep((rand()%8)*500+500);
    printf("Slot %d idle\n", n);
    return ((DWORD)n);
}