comm_select.c

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	    FD_SET(fd, &write_mask);
	    if (fd > maxfd)
		maxfd = fd;
	}
    }
    if (maxfd++ == 0)
	return incame;
#if !ALARM_UPDATES_TIME
    getCurrentTime();
#endif
    Counter.syscalls.selects++;
    if (select(maxfd, &read_mask, &write_mask, NULL, &zero_tv) < 1)
	return incame;
    for (i = 0; i < nfds; i++) {
	fd = fds[i];
	if (FD_ISSET(fd, &read_mask)) {
	    if ((hdl = fd_table[fd].read_handler) != NULL) {
		fd_table[fd].read_handler = NULL;
		commUpdateReadBits(fd, NULL);
		hdl(fd, &incame);
	    } else {
		debug(5, 1) ("comm_select_incoming: NULL read handler\n");
	    }
	}
	if (FD_ISSET(fd, &write_mask)) {
	    if ((hdl = fd_table[fd].write_handler) != NULL) {
		fd_table[fd].write_handler = NULL;
		commUpdateWriteBits(fd, NULL);
		hdl(fd, &incame);
	    } else {
		debug(5, 1) ("comm_select_incoming: NULL write handler\n");
	    }
	}
    }
    return incame;
}

static void
comm_select_icp_incoming(void)
{
    int nfds = 0;
    int fds[2];
    int nevents;
    icp_io_events = 0;
    if (theInIcpConnection >= 0)
	fds[nfds++] = theInIcpConnection;
    if (theInIcpConnection != theOutIcpConnection)
	if (theOutIcpConnection >= 0)
	    fds[nfds++] = theOutIcpConnection;
    if (nfds == 0)
	return;
    nevents = comm_check_incoming_select_handlers(nfds, fds);
    incoming_icp_interval += Config.comm_incoming.icp_average - nevents;
    if (incoming_icp_interval < 0)
	incoming_icp_interval = 0;
    if (incoming_icp_interval > MAX_INCOMING_INTERVAL)
	incoming_icp_interval = MAX_INCOMING_INTERVAL;
    if (nevents > INCOMING_ICP_MAX)
	nevents = INCOMING_ICP_MAX;
    statHistCount(&Counter.comm_icp_incoming, nevents);
}

static void
comm_select_http_incoming(void)
{
    int nfds = 0;
    int fds[MAXHTTPPORTS];
    int j;
    int nevents;
    http_io_events = 0;
    for (j = 0; j < NHttpSockets; j++) {
	if (HttpSockets[j] < 0)
	    continue;
	if (commDeferRead(HttpSockets[j]))
	    continue;
	fds[nfds++] = HttpSockets[j];
    }
    nevents = comm_check_incoming_select_handlers(nfds, fds);
    incoming_http_interval += Config.comm_incoming.http_average - nevents;
    if (incoming_http_interval < 0)
	incoming_http_interval = 0;
    if (incoming_http_interval > MAX_INCOMING_INTERVAL)
	incoming_http_interval = MAX_INCOMING_INTERVAL;
    if (nevents > INCOMING_HTTP_MAX)
	nevents = INCOMING_HTTP_MAX;
    statHistCount(&Counter.comm_http_incoming, nevents);
}

#define DEBUG_FDBITS 0
/* Select on all sockets; call handlers for those that are ready. */
int
comm_select(int msec)
{
    fd_set readfds;
    fd_set writefds;
    PF *hdl = NULL;
    int fd;
    int maxfd;
    int num;
    int callicp = 0, callhttp = 0;
    int maxindex;
    int k;
    int j;
#if DEBUG_FDBITS
    int i;
#endif
    fd_mask *fdsp;
    fd_mask tmask;
    static time_t last_timeout = 0;
    struct timeval poll_time;
    double timeout = current_dtime + (msec / 1000.0);
    fde *F;
    do {
#if !ALARM_UPDATES_TIME
	getCurrentTime();
#endif
#if USE_ASYNC_IO
	aioCheckCallbacks();
#endif
	if (commCheckICPIncoming)
	    comm_select_icp_incoming();
	if (commCheckHTTPIncoming)
	    comm_select_http_incoming();
	callicp = callhttp = 0;
	maxfd = Biggest_FD + 1;
	xmemcpy(&readfds, &global_readfds,
	    howmany(maxfd, FD_MASK_BITS) * FD_MASK_BYTES);
	xmemcpy(&writefds, &global_writefds,
	    howmany(maxfd, FD_MASK_BITS) * FD_MASK_BYTES);
	/* remove stalled FDs */
	maxindex = howmany(maxfd, FD_MASK_BITS);
	fdsp = (fd_mask *) & readfds;
	for (j = 0; j < maxindex; j++) {
	    if ((tmask = fdsp[j]) == 0)
		continue;	/* no bits here */
	    for (k = 0; k < FD_MASK_BITS; k++) {
		if (!EBIT_TEST(tmask, k))
		    continue;
		/* Found a set bit */
		fd = (j * FD_MASK_BITS) + k;
		if (commDeferRead(fd))
		    FD_CLR(fd, &readfds);
	    }
	}
#if DEBUG_FDBITS
	for (i = 0; i < maxfd; i++) {
	    /* Check each open socket for a handler. */
	    if (fd_table[i].read_handler && !commDeferRead(i)) {
		assert(FD_ISSET(i, &readfds));
	    }
	    if (fd_table[i].write_handler) {
		assert(FD_ISSET(i, &writefds));
	    }
	}
#endif
	if (nreadfds + nwritefds == 0) {
	    assert(shutting_down);
	    return COMM_SHUTDOWN;
	}
	if (msec > MAX_POLL_TIME)
	    msec = MAX_POLL_TIME;
#ifdef _SQUID_OS2_
	if (msec < 0)
	    msec = MAX_POLL_TIME;
#endif
	for (;;) {
	    poll_time.tv_sec = msec / 1000;
	    poll_time.tv_usec = (msec % 1000) * 1000;
	    Counter.syscalls.selects++;
	    num = select(maxfd, &readfds, &writefds, NULL, &poll_time);
	    Counter.select_loops++;
	    if (num >= 0)
		break;
	    if (ignoreErrno(errno))
		break;
	    debug(50, 0) ("comm_select: select failure: %s\n",
		xstrerror());
	    examine_select(&readfds, &writefds);
	    return COMM_ERROR;
	    /* NOTREACHED */
	}
	if (num < 0)
	    continue;
	debug(5, num ? 5 : 8) ("comm_select: %d FDs ready at %d\n",
	    num, (int) squid_curtime);
	statHistCount(&Counter.select_fds_hist, num);
	/* Check lifetime and timeout handlers ONCE each second.
	 * Replaces brain-dead check every time through the loop! */
	if (squid_curtime > last_timeout) {
	    last_timeout = squid_curtime;
	    checkTimeouts();
	}
	if (num == 0)
	    continue;
	/* Scan return fd masks for ready descriptors */
	fdsp = (fd_mask *) & readfds;
	maxindex = howmany(maxfd, FD_MASK_BITS);
	for (j = 0; j < maxindex; j++) {
	    if ((tmask = fdsp[j]) == 0)
		continue;	/* no bits here */
	    for (k = 0; k < FD_MASK_BITS; k++) {
		if (!EBIT_TEST(tmask, k))
		    continue;
		/* Found a set bit */
		fd = (j * FD_MASK_BITS) + k;
#if DEBUG_FDBITS
		debug(5, 9) ("FD %d bit set for reading\n", fd);
		assert(FD_ISSET(fd, &readfds));
#endif
		if (fdIsIcp(fd)) {
		    callicp = 1;
		    continue;
		}
		if (fdIsHttp(fd)) {
		    callhttp = 1;
		    continue;
		}
		F = &fd_table[fd];
		debug(5, 6) ("comm_select: FD %d ready for reading\n", fd);
		if (F->read_handler) {
		    hdl = F->read_handler;
		    F->read_handler = NULL;
		    commUpdateReadBits(fd, NULL);
		    hdl(fd, F->read_data);
		    Counter.select_fds++;
		}
		if (commCheckICPIncoming)
		    comm_select_icp_incoming();
		if (commCheckHTTPIncoming)
		    comm_select_http_incoming();
		EBIT_CLR(tmask, k);	/* this bit is done */
		if (tmask == 0)
		    break;	/* and no more bits left */
	    }
	}
	fdsp = (fd_mask *) & writefds;
	for (j = 0; j < maxindex; j++) {
	    if ((tmask = fdsp[j]) == 0)
		continue;	/* no bits here */
	    for (k = 0; k < FD_MASK_BITS; k++) {
		if (!EBIT_TEST(tmask, k))
		    continue;
		/* Found a set bit */
		fd = (j * FD_MASK_BITS) + k;
#if DEBUG_FDBITS
		debug(5, 9) ("FD %d bit set for writing\n", fd);
		assert(FD_ISSET(fd, &writefds));
#endif
		if (fdIsIcp(fd)) {
		    callicp = 1;
		    continue;
		}
		if (fdIsHttp(fd)) {
		    callhttp = 1;
		    continue;
		}
		F = &fd_table[fd];
		debug(5, 5) ("comm_select: FD %d ready for writing\n", fd);
		if (F->write_handler) {
		    hdl = F->write_handler;
		    F->write_handler = NULL;
		    commUpdateWriteBits(fd, NULL);
		    hdl(fd, F->write_data);
		    Counter.select_fds++;
		}
		if (commCheckICPIncoming)
		    comm_select_icp_incoming();
		if (commCheckHTTPIncoming)
		    comm_select_http_incoming();
		EBIT_CLR(tmask, k);	/* this bit is done */
		if (tmask == 0)
		    break;	/* and no more bits left */
	    }
	}
	if (callicp)
	    comm_select_icp_incoming();
	if (callhttp)
	    comm_select_http_incoming();
	return COMM_OK;
    } while (timeout > current_dtime);
    debug(5, 8) ("comm_select: time out: %d\n", (int) squid_curtime);
    return COMM_TIMEOUT;
}
#endif

void
comm_select_init(void)
{
    zero_tv.tv_sec = 0;
    zero_tv.tv_usec = 0;
    cachemgrRegister("comm_incoming",
	"comm_incoming() stats",
	commIncomingStats, 0, 1);
    FD_ZERO(&global_readfds);
    FD_ZERO(&global_writefds);
    nreadfds = nwritefds = 0;
}

#if !HAVE_POLL
/*
 * examine_select - debug routine.
 *
 * I spend the day chasing this core dump that occurs when both the client
 * and the server side of a cache fetch simultaneoulsy abort the
 * connection.  While I haven't really studied the code to figure out how
 * it happens, the snippet below may prevent the cache from exitting:
 * 
 * Call this from where the select loop fails.
 */
static int
examine_select(fd_set * readfds, fd_set * writefds)
{
    int fd = 0;
    fd_set read_x;
    fd_set write_x;
    struct timeval tv;
    close_handler *ch = NULL;
    fde *F = NULL;
    struct stat sb;
    debug(5, 0) ("examine_select: Examining open file descriptors...\n");
    for (fd = 0; fd < Squid_MaxFD; fd++) {
	FD_ZERO(&read_x);
	FD_ZERO(&write_x);
	tv.tv_sec = tv.tv_usec = 0;
	if (FD_ISSET(fd, readfds))
	    FD_SET(fd, &read_x);
	else if (FD_ISSET(fd, writefds))
	    FD_SET(fd, &write_x);
	else
	    continue;
	Counter.syscalls.selects++;
	errno = 0;
	if (!fstat(fd, &sb)) {
	    debug(5, 5) ("FD %d is valid.\n", fd);
	    continue;
	}
	F = &fd_table[fd];
	debug(5, 0) ("FD %d: %s\n", fd, xstrerror());
	debug(5, 0) ("WARNING: FD %d has handlers, but it's invalid.\n", fd);
	debug(5, 0) ("FD %d is a %s called '%s'\n",
	    fd,
	    fdTypeStr[F->type],
	    F->desc);
	debug(5, 0) ("tmout:%p read:%p write:%p\n",
	    F->timeout_handler,
	    F->read_handler,
	    F->write_handler);
	for (ch = F->close_handler; ch; ch = ch->next)
	    debug(5, 0) (" close handler: %p\n", ch->handler);
	if (F->close_handler) {
	    commCallCloseHandlers(fd);
	} else if (F->timeout_handler) {
	    debug(5, 0) ("examine_select: Calling Timeout Handler\n");
	    F->timeout_handler(fd, F->timeout_data);
	}
	F->close_handler = NULL;
	F->timeout_handler = NULL;
	F->read_handler = NULL;
	F->write_handler = NULL;
	FD_CLR(fd, readfds);
	FD_CLR(fd, writefds);
    }
    return 0;
}
#endif

static void
checkTimeouts(void)
{
    int fd;
    fde *F = NULL;
    PF *callback;
    for (fd = 0; fd <= Biggest_FD; fd++) {
	F = &fd_table[fd];
	if (!F->flags.open)
	    continue;
	if (F->timeout == 0)
	    continue;
	if (F->timeout > squid_curtime)
	    continue;
	debug(5, 5) ("checkTimeouts: FD %d Expired\n", fd);
	if (F->timeout_handler) {
	    debug(5, 5) ("checkTimeouts: FD %d: Call timeout handler\n", fd);
	    callback = F->timeout_handler;
	    F->timeout_handler = NULL;
	    callback(fd, F->timeout_data);
	} else {
	    debug(5, 5) ("checkTimeouts: FD %d: Forcing comm_close()\n", fd);
	    comm_close(fd);
	}
    }
}

static void
commIncomingStats(StoreEntry * sentry)
{
    StatCounters *f = &Counter;
    storeAppendPrintf(sentry, "Current incoming_icp_interval: %d\n",
	incoming_icp_interval >> INCOMING_FACTOR);
    storeAppendPrintf(sentry, "Current incoming_http_interval: %d\n",
	incoming_http_interval >> INCOMING_FACTOR);
    storeAppendPrintf(sentry, "\n");
    storeAppendPrintf(sentry, "Histogram of events per incoming socket type\n");
#ifdef HAVE_POLL
    storeAppendPrintf(sentry, "ICP Messages handled per comm_poll_icp_incoming() call:\n");
#else
    storeAppendPrintf(sentry, "ICP Messages handled per comm_select_icp_incoming() call:\n");
#endif
    statHistDump(&f->comm_icp_incoming, sentry, statHistIntDumper);
#ifdef HAVE_POLL
    storeAppendPrintf(sentry, "HTTP Messages handled per comm_poll_http_incoming() call:\n");
#else
    storeAppendPrintf(sentry, "HTTP Messages handled per comm_select_http_incoming() call:\n");
#endif
    statHistDump(&f->comm_http_incoming, sentry, statHistIntDumper);
}

void
commUpdateReadBits(int fd, PF * handler)
{
    if (handler && !FD_ISSET(fd, &global_readfds)) {
	FD_SET(fd, &global_readfds);
	nreadfds++;
    } else if (!handler && FD_ISSET(fd, &global_readfds)) {
	FD_CLR(fd, &global_readfds);
	nreadfds--;
    }
}

void
commUpdateWriteBits(int fd, PF * handler)
{
    if (handler && !FD_ISSET(fd, &global_writefds)) {
	FD_SET(fd, &global_writefds);
	nwritefds++;
    } else if (!handler && FD_ISSET(fd, &global_writefds)) {
	FD_CLR(fd, &global_writefds);
	nwritefds--;
    }
}