Postmaster主循环的大致流程

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mob604756f7c87d 2012-07-20 08:34:00

文章标签 Postgresql postmaster i++ 数组 c语言 文章分类 代码人生

postmaster.c 中，主循环的大致流程如下：

/*                                    
 * Main idle loop of postmaster                                    
 */                                    
static int                                    
ServerLoop(void)                                    
{                                    
    ......                       
    nSockets = initMasks(&readmask);                                
                              
    for (;;)                                
    {                                
        ...                                        
        if (pmState == PM_WAIT_DEAD_END)                            
        {
            ...
        }                            
        else                            
        {
            ...                                                     
            selres = select(nSockets, &rmask, NULL, NULL, &timeout);   
        }                            
        ...                           
                                    
        /* Now check the select() result */                            
        if (selres < 0)                            
        {                            
            if (errno != EINTR && errno != EWOULDBLOCK)                        
            {                        
                ......           
                return STATUS_ERROR;                    
            }                        
        }                            
                                    
        /*                            
         * New connection pending on any of our sockets? If so, fork a child 
         * process to deal with it.                            
         */                            
        if (selres > 0)                            
        {                            
            int            i;            
                                    
            for (i = 0; i < MAXLISTEN; i++)                        
            {                        
                if (ListenSocket[i] == PGINVALID_SOCKET)                    
                    break;                
                                    
                if (FD_ISSET(ListenSocket[i], &rmask))                    
                {                    
                    Port       *port; 
                    port = ConnCreate(ListenSocket[i]);                
                                    
                    if (port)                
                    {                
                        BackendStartup(port);   /*To fork a new backend */         
      
                        StreamClose(port->sock);            
                        ConnFree(port);            
                    }                
                }                    
            }                        
        }                            
                                    
        ......                        
    }                                
}