
/*
 * $Id: pconn.c,v 1.6.38.2 2003/12/16 03:13:59 squidadm Exp $
 *
 * DEBUG: section 48    Persistent Connections
 * AUTHOR: Duane Wessels
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
 *
 */

#include "squid.h"

struct _pconn {
    hash_link hash;            /* must be first */
    int *fds;
    int nfds_alloc;
    int nfds;
};
typedef struct _pconn pconn;

#define PCONN_FDS_SZ   8       /* pconn set size, increase for better memcache hit rate */
#define PCONN_HIST_SZ (1<<16)
int client_pconn_hist[PCONN_HIST_SZ];
int server_pconn_hist[PCONN_HIST_SZ];

static PF pconnRead;
static PF pconnTimeout;
static const char *pconnKey(const char *host, u_short port);
static hash_table *table = NULL;
static struct _pconn *pconnNew(const char *key);
static void pconnDelete(struct _pconn *p);
static void pconnRemoveFD(struct _pconn *p, int fd);
static OBJH pconnHistDump;
static MemPool *pconn_data_pool = NULL;
static MemPool *pconn_fds_pool = NULL;

static const char *
pconnKey(const char *host, u_short port)
{
    LOCAL_ARRAY(char, buf, SQUIDHOSTNAMELEN + 10);
    snprintf(buf, SQUIDHOSTNAMELEN + 10, "%s.%d", host, (int) port);
    return buf;
}

static struct _pconn *
pconnNew(const char *key)
{
    struct _pconn *p = (_pconn*)memPoolAlloc(pconn_data_pool);
    p->hash.key = xstrdup(key);
    p->nfds_alloc = PCONN_FDS_SZ;
    p->fds = (int *)memPoolAlloc(pconn_fds_pool);
    debug(48, 3) ("pconnNew: adding %s\n", hashKeyStr(&p->hash));
    hash_join(table, &p->hash);
    return p;
}

static void
pconnDelete(struct _pconn *p)
{
    debug(48, 3) ("pconnDelete: deleting %s\n", hashKeyStr(&p->hash));
    hash_remove_link(table, (hash_link *) p);
    if (p->nfds_alloc == PCONN_FDS_SZ)
       memPoolFree(pconn_fds_pool, p->fds);
    else
       xfree(p->fds);
    xfree(p->hash.key);
    memPoolFree(pconn_data_pool, p);
}

static void
pconnRemoveFD(struct _pconn *p, int fd)
{
    int i;
    for (i = p->nfds - 1; i >= 0; i--) {
       if (p->fds[i] == fd)
           break;
    }
    assert(i >= 0);
    debug(48, 3) ("pconnRemoveFD: found FD %d at index %d\n", fd, i);
    for (; i < p->nfds - 1; i++)
       p->fds[i] = p->fds[i + 1];
    if (--p->nfds == 0)
       pconnDelete(p);
}

static void
pconnTimeout(int fd, void *data)
{
    struct _pconn *p = (struct _pconn *)data;
    assert(table != NULL);
    debug(48, 3) ("pconnTimeout: FD %d %s\n", fd, hashKeyStr(&p->hash));
    pconnRemoveFD(p, fd);
    comm_close(fd);
}

static void
pconnRead(int fd, void *data)
{
    LOCAL_ARRAY(char, buf, 256);
    struct _pconn *p = (struct _pconn *)data;
    int n;
    assert(table != NULL);
    statCounter.syscalls.sock.reads++;
    n = squid_fd_table.fd_table[fd].read(buf, 256);
    debug(48, 3) ("pconnRead: %d bytes from FD %d, %s\n", n, fd,
       hashKeyStr(&p->hash));
    pconnRemoveFD(p, fd);
    comm_close(fd);
}

static void
pconnHistDump(StoreEntry * e)
{
    int i;
    storeAppendPrintf(e,
       "Client-side persistent connection counts:\n"
       "\n"
       "\treq/\n"
       "\tconn      count\n"
       "\t----  ---------\n");
    for (i = 0; i < PCONN_HIST_SZ; i++) {
       if (client_pconn_hist[i] == 0)
           continue;
       storeAppendPrintf(e, "\t%4d  %9d\n", i, client_pconn_hist[i]);
    }
    storeAppendPrintf(e,
       "\n"
       "Server-side persistent connection counts:\n"
       "\n"
       "\treq/\n"
       "\tconn      count\n"
       "\t----  ---------\n");
    for (i = 0; i < PCONN_HIST_SZ; i++) {
       if (server_pconn_hist[i] == 0)
           continue;
       storeAppendPrintf(e, "\t%4d  %9d\n", i, server_pconn_hist[i]);
    }
}

/* ========== PUBLIC FUNCTIONS ============================================ */


void
pconnInit(void)
{
    int i;
    assert(table == NULL);
    table = hash_create((HASHCMP *) strcmp, 229, hash_string);
    for (i = 0; i < PCONN_HIST_SZ; i++) {
       client_pconn_hist[i] = 0;
       server_pconn_hist[i] = 0;
    }
   pconn_data_pool = memPoolCreate("pconn_data", sizeof(struct _pconn));
   pconn_fds_pool = memPoolCreate("pconn_fds", PCONN_FDS_SZ * sizeof(int));

    cachemgrRegister("pconn",
       "Persistent Connection Utilization Histograms",
       pconnHistDump, 0, 1);
    debug(48, 3) ("persistent connection module initialized\n");
}

void
pconnPush(int fd, const char *host, u_short port)
{
    struct _pconn *p;
    int *old;
    LOCAL_ARRAY(char, key, SQUIDHOSTNAMELEN + 10);
    LOCAL_ARRAY(char, desc, FD_DESC_SZ);
    if (fdUsageHigh()) {
       debug(48, 3) ("pconnPush: Not many unused FDs\n");
       comm_close(fd);
       return;
    } else if (shutting_down) {
       comm_close(fd);
       return;
    }
    assert(table != NULL);
    strcpy(key, pconnKey(host, port));
    p = (struct _pconn *) hash_lookup(table, key);
    if (p == NULL)
       p = pconnNew(key);
    if (p->nfds == p->nfds_alloc) {
       debug(48, 3) ("pconnPush: growing FD array\n");
       p->nfds_alloc <<= 1;
       old = p->fds;
       p->fds = (int *)xmalloc(p->nfds_alloc * sizeof(int));
       xmemcpy(p->fds, old, p->nfds * sizeof(int));
       if (p->nfds == PCONN_FDS_SZ)
           memPoolFree(pconn_fds_pool, old);
       else
           xfree(old);
    }
    p->fds[p->nfds++] = fd;
    commSetSelect(fd, COMM_SELECT_READ, pconnRead, p, 0);
    commSetTimeout(fd, Config.Timeout.pconn, pconnTimeout, p);
    snprintf(desc, FD_DESC_SZ, "%s idle connection", host);
    fd_note(fd, desc);
    debug(48, 3) ("pconnPush: pushed FD %d for %s\n", fd, key);
}

int
pconnPop(const char *host, u_short port)
{
    struct _pconn *p;
    hash_link *hptr;
    int fd = -1;
    LOCAL_ARRAY(char, key, SQUIDHOSTNAMELEN + 10);
    assert(table != NULL);
    strcpy(key, pconnKey(host, port));
    hptr = (hash_link *)hash_lookup(table, key);
    if (hptr != NULL) {
       p = (struct _pconn *) hptr;
       assert(p->nfds > 0);
	fd = p->fds[p->nfds - 1];
       pconnRemoveFD(p, fd);
       commSetSelect(fd, COMM_SELECT_READ, NULL, NULL, 0);
       commSetTimeout(fd, -1, NULL, NULL);
    }
    return fd;
}

void
pconnHistCount(int what, int i)
{
    if (i >= PCONN_HIST_SZ)
       i = PCONN_HIST_SZ - 1;
    /* what == 0 for client, 1 for server */
    if (what == 0)
       client_pconn_hist[i]++;
    else if (what == 1)
       server_pconn_hist[i]++;
    else
       assert(0);
}
