tcptimer.c,v

来自「关于TCP方面的」· C,V 代码 · 共 93 行

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date	97.09.21.19.29.52;	author dls;	state Dist;
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date	94.01.14.03.51.20;	author dls;	state v2e1;
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@pre-3e code
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@/* tcptimer.c - tcptimer */

#include <conf.h>
#include <kernel.h>
#include <network.h>
#include <tcptimer.h>

int	tqmutex;
int	tqpid;
struct	tqent	*tqhead;

/*------------------------------------------------------------------------
 *  tcptimer -  TCP timer process
 *------------------------------------------------------------------------
 */
PROCESS tcptimer()
{
	long	now, lastrun;		/* times from system clock	*/
	int	delta;			/* time since last iteration	*/
	struct	tqent	*tq;		/* temporary delta list ptr	*/

	lastrun = ctr100;		/* initialize to "now"		*/
	tqmutex = screate(1);		/* mutual exclusion semaphore	*/
	tqpid = getpid();		/* record timer process id	*/
	signal(Net.sema);		/* start other network processes*/

	while (TRUE) {
		sleep10(TIMERGRAN);	/* real-time delay		*/
		if (tqhead == 0)	/* block timer process if delta	*/
			suspend(tqpid);	/*   list is empty		*/

		wait(tqmutex);
		now = ctr100;
		delta = now - lastrun;	/* compute elapsed time		*/

		/* Note: check for possible clock reset (time moved	*/
		/* backward or delay was over an order of magnitude too	*/
		/* long)						*/

		if (delta < 0 || delta > TIMERGRAN*100)
			delta = TIMERGRAN*10;	/* estimate the delay	*/
		lastrun = now;
		while (tqhead != 0  &&  tqhead->tq_timeleft <= delta) {
			delta -= tqhead->tq_timeleft;
			if (pcount(tqhead->tq_port) <= tqhead->tq_portlen)
				psend(tqhead->tq_port, tqhead->tq_msg);
			tq = tqhead;
			tqhead = tqhead->tq_next;
			freemem(tq, sizeof(struct tqent));
		}
		if (tqhead)
			tqhead->tq_timeleft -=delta;
		signal(tqmutex);
	}
}
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