pipeserver.c

vxworks 下多线程编程事例代码 包括：管道

/* pipeServer.c - Demonstrates intertask communication using pipes */
 
 /* Copyright 1984-1997 Wind River Systems, Inc. */
 
 /*
 modification history
 --------------------
 01c,06nov97,mm  added copyright.
 01b,19sep97,ram need to add INCLUDE_PIPE in configAll.h
 		 added include files stdio.h,ioLib.h,pipeDrv.h
 01a,11mar94,ms   cleaned up for VxDemo
 */
 
 
 /* DESCRIPTION
  *
  * Demonstrates intertask communication using pipes.
  *
  * serverStart initializes a server task to execute functions
  * at a low priority and uses pipes as the communication
  * mechanism. 
  *
  * serverSend sends a request to the server to execute a 
  * function at the server's  priority using pipe device.
  * Usage : serverSend (<function>, <argument of the function>)
  *
  * EXAMPLE
  * To run this demo from the Wind shell do as follows:
  *
  * -> serverStart
  * value = 0 = 0x0
  * -> serverSend (printf,"Hello World. \n")
  * value = 0 = 0x0
  *
  * NOTE: A host function such as i() cannot be used as the function
  *       argument to serveSend.
  *	 eg: -> serverSend(i,"tShell") will not work
  *       However if you wish to do that then make sure to add
  *	 INCLUDE_CONFIGURATION_5_2 and INCLUDE_DEBUG in configAll.h
 */
 
 /* includes */
 
 #include "vxWorks.h"
 #include "taskLib.h"
 #include "stdio.h"
 #include "ioLib.h"
 #include "pipeDrv.h"
 
 
 typedef struct
     {
     VOIDFUNCPTR routine;
     int arg;
     } MSG_REQUEST; 	                        /* message structure */
 
 
 #define TASK_PRI		254             /* tServers task's priority */
 #define TASK_STACK_SIZE         5000            /* tServer task's stack size */
 #define PIPE_NAME		"/pipe/server"  /* name of the pipe device */
 #define NUM_MSGS                10     /* max number of messages in the pipe */
 
 LOCAL int pipeFd;                     /* File descriptor for the pipe device */
 LOCAL void pipeServer ();             /* server task */
 
 
 /***********************************************************************
  * serverStart -- Initializes a server task to execute functons
  *                at a low priority.  Uses pipes as the communication
  *                mechanism.
  *
  * RETURNS: OK or ERROR on failure.
  */
 
 STATUS serverStart ()
     {
 
     if (pipeDevCreate (PIPE_NAME, NUM_MSGS, sizeof (MSG_REQUEST)) == ERROR)
         {
         perror ("Error in creating pipe"); /* print error if pipe is already 
                                             * created, but do not return */
         }
 
     /* Open the pipe */
     if ((pipeFd = open (PIPE_NAME, UPDATE, 0)) == ERROR)
         {
         perror  ("Error in opening pipe device");
         return (ERROR);
         }
 	
     /* Spawn the server task */
     if (taskSpawn ("tServer", TASK_PRI, 0, TASK_STACK_SIZE, 
                    (FUNCPTR) pipeServer, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) 
                    == ERROR)
         {
         perror ("Error in spawning tServer task");
 	close (pipeFd);
 	return (ERROR);
 	}
 	
     return (OK);
     }
 
 /**************************************************************
  * serverSend -- Sends a request to the server to execute a 
  *               function at the server's  priority.
  *
  * RETURNS: OK or ERROR on failure.
  */
 
 STATUS serverSend 
     (
     VOIDFUNCPTR routine,              /* name of the routine to execute */
     int arg                           /* argument of the routine */        
     )
     {
     MSG_REQUEST msgRequest;
     int status;
 
     /* Initialize the message structure */
     msgRequest.routine = routine;
     msgRequest.arg     = arg;
 
     /* Send the message and return the results */
     status = write (pipeFd, (char *)&msgRequest, sizeof (MSG_REQUEST));
 
     return ((status == sizeof (MSG_REQUEST)) ? OK : ERROR);
     }
 
 /*************************************************************************
  * pipeServer -- Server task which reads from a pipe and executes
  *               the function passed in the MSG_REQUEST data structure.
  *
  */
 
 LOCAL void pipeServer ()
 	{
 	MSG_REQUEST msgRequest;
 
 	while (read (pipeFd, (char *)&msgRequest, sizeof (MSG_REQUEST)) > 0)
 		(*msgRequest.routine) (msgRequest.arg);
 		}