/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 *
 * Portal-RPC reconnection and replay operations, for use in recovery.
 *
 *  Copyright (c) 2003 Cluster File Systems, Inc.
 *   Authors: Phil Schwan <phil@clusterfs.com>
 *            Mike Shaver <shaver@clusterfs.com>
 *
 *   This file is part of Lustre, http://www.lustre.org.
 *
 *   Lustre is free software; you can redistribute it and/or
 *   modify it under the terms of version 2 of the GNU General Public
 *   License as published by the Free Software Foundation.
 *
 *   Lustre 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 Lustre; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifndef __KERNEL__
#include <liblustre.h>
#else
#include <linux/version.h>
#include <asm/semaphore.h>
#define DEBUG_SUBSYSTEM S_RPC
#endif

#include <linux/obd_support.h>
#include <linux/obd_class.h>
#include "ptlrpc_internal.h"

#define PINGER_RATE     3 /* how many pings we'll do in obd_timeout period */

static DECLARE_MUTEX(pinger_sem);
static struct list_head pinger_imports = LIST_HEAD_INIT(pinger_imports);

int ptlrpc_ping(struct obd_import *imp) 
{
        struct ptlrpc_request *req;
        int rc = 0;
        ENTRY;

        req = ptlrpc_prep_req(imp, LUSTRE_OBD_VERSION, OBD_PING, 0, NULL, NULL);
        if (req) {
                DEBUG_REQ(D_HA, req, "pinging %s->%s",
                          imp->imp_obd->obd_uuid.uuid,
                          imp->imp_target_uuid.uuid);
                req->rq_no_resend = req->rq_no_delay = 1;
                req->rq_replen = lustre_msg_size(0, NULL);
                req->rq_timeout = obd_timeout / PINGER_RATE;
                ptlrpcd_add_req(req);
        } else {
                CERROR("OOM trying to ping %s->%s\n",
                       imp->imp_obd->obd_uuid.uuid,
                       imp->imp_target_uuid.uuid);
                rc = -ENOMEM;
        }

        RETURN(rc);
}

#ifdef __KERNEL__
static inline int ptlrpc_next_ping(struct obd_import *imp)
{
        return jiffies + (obd_timeout / PINGER_RATE * HZ);
}

static inline int ptlrpc_next_reconnect(struct obd_import *imp)
{
        if (imp->imp_server_timeout)
                return jiffies + (obd_timeout / 2 * HZ);
        else
                return jiffies + (obd_timeout * HZ);
}

static atomic_t suspend_timeouts = ATOMIC_INIT(0);
static wait_queue_head_t suspend_timeouts_waitq;

void ptlrpc_deactivate_timeouts(void)
{
        CDEBUG(D_HA, "deactivate timeouts\n");
        atomic_inc(&suspend_timeouts);
}
                
void ptlrpc_activate_timeouts(void)
{
        CDEBUG(D_HA, "activate timeouts\n");
        LASSERT(atomic_read(&suspend_timeouts) > 0);
        if (atomic_dec_and_test(&suspend_timeouts))
                wake_up(&suspend_timeouts_waitq);
}

int ptlrpc_check_suspend(void)
{
        if (atomic_read(&suspend_timeouts))
                return 1;
        return 0;
}

int ptlrpc_check_and_wait_suspend(struct ptlrpc_request *req)
{
        struct l_wait_info lwi;

        if (atomic_read(&suspend_timeouts)) {
                DEBUG_REQ(D_NET, req, "-- suspend %d regular timeout",
                          atomic_read(&suspend_timeouts));
                lwi = LWI_INTR(NULL, NULL);
                l_wait_event(suspend_timeouts_waitq,
                             atomic_read(&suspend_timeouts) == 0, &lwi);
                DEBUG_REQ(D_NET, req, "-- recharge regular timeout");
                return 1;
        }
        return 0;
}

static void ptlrpc_pinger_process_import(struct obd_import *imp,
                                         unsigned long this_ping)
{
        unsigned long flags;
        int force, level;

        spin_lock_irqsave(&imp->imp_lock, flags);
        level = imp->imp_state;
        force = imp->imp_force_verify;
        if (force)
                imp->imp_force_verify = 0;
        spin_unlock_irqrestore(&imp->imp_lock, flags);

        if (imp->imp_next_ping - this_ping > obd_timeout * HZ) {
                CWARN("wrong ping time %lu (current %lu)\n",
                      imp->imp_next_ping, this_ping);
                imp->imp_next_ping = ptlrpc_next_reconnect(imp);
        }

        if (imp->imp_next_ping > this_ping && force == 0)
                return;

        if (level == LUSTRE_IMP_DISCON && !imp->imp_deactive) {
                /* wait at least a timeout before trying recovery again */
                imp->imp_next_ping = ptlrpc_next_reconnect(imp);
                ptlrpc_initiate_recovery(imp);
        } else if (level != LUSTRE_IMP_FULL || imp->imp_obd->obd_no_recov) {
                CDEBUG(D_HA, "not pinging %s (in recovery "
                       " or recovery disabled: %s)\n",
                       imp->imp_target_uuid.uuid,
                       ptlrpc_import_state_name(level));
        } else if (imp->imp_pingable || force) {
                imp->imp_next_ping = ptlrpc_next_ping(imp);
                ptlrpc_ping(imp);
        }
}

static int ptlrpc_pinger_main(void *arg)
{
        struct ptlrpc_svc_data *data = (struct ptlrpc_svc_data *)arg;
        struct ptlrpc_thread *thread = data->thread;
        unsigned long flags;
        ENTRY;

        lock_kernel();
        ptlrpc_daemonize();

        SIGNAL_MASK_LOCK(current, flags);
        sigfillset(&current->blocked);
        RECALC_SIGPENDING;
        SIGNAL_MASK_UNLOCK(current, flags);

        LASSERTF(strlen(data->name) < sizeof(current->comm),
                 "name %d > len %d\n",
                 (int)strlen(data->name), (int)sizeof(current->comm));
        THREAD_NAME(current->comm, sizeof(current->comm) - 1, "%s", data->name);
        unlock_kernel();

        /* Record that the thread is running */
        thread->t_flags = SVC_RUNNING;
        wake_up(&thread->t_ctl_waitq);

        /* And now, loop forever, pinging as needed. */
        while (1) {
                unsigned long this_ping = jiffies;
                long time_to_next_ping;
                struct l_wait_info lwi = LWI_TIMEOUT(obd_timeout * HZ,
                                                     NULL, NULL);
                struct list_head *iter;

                time_to_next_ping = this_ping + (obd_timeout * HZ) - jiffies;
                down(&pinger_sem);
                list_for_each(iter, &pinger_imports) {
                        struct obd_import *imp =
                                list_entry(iter, struct obd_import,
                                           imp_pinger_chain);

                        ptlrpc_pinger_process_import(imp, this_ping);

                        CDEBUG(D_OTHER, "%s: pingable %d, next_ping %lu(%lu)\n",
                                imp->imp_target_uuid.uuid,
                                imp->imp_pingable, imp->imp_next_ping, jiffies);

                        if (imp->imp_pingable && imp->imp_next_ping &&
                            imp->imp_next_ping - jiffies < time_to_next_ping &&
                            imp->imp_next_ping > jiffies)
                                time_to_next_ping = imp->imp_next_ping - jiffies;
                }
                up(&pinger_sem);

                /* Wait until the next ping time, or until we're stopped. */
                CDEBUG(D_HA, "next ping in %lu (%lu)\n", time_to_next_ping,
                       this_ping + (obd_timeout * HZ));
                if (time_to_next_ping > 0) {
                        lwi = LWI_TIMEOUT(time_to_next_ping, NULL, NULL);
                        l_wait_event(thread->t_ctl_waitq,
                                     thread->t_flags & (SVC_STOPPING|SVC_EVENT),
                                     &lwi);
                        if (thread->t_flags & SVC_STOPPING) {
                                thread->t_flags &= ~SVC_STOPPING;
                                EXIT;
                                break;
                        } else if (thread->t_flags & SVC_EVENT) {
                                /* woken after adding import to reset timer */
                                thread->t_flags &= ~SVC_EVENT;
                        }
                }
        }

        thread->t_flags = SVC_STOPPED;
        wake_up(&thread->t_ctl_waitq);

        CDEBUG(D_NET, "pinger thread exiting, process %d\n", current->pid);
        return 0;
}

static struct ptlrpc_thread *pinger_thread = NULL;

int ptlrpc_start_pinger(void)
{
        struct l_wait_info lwi = { 0 };
        struct ptlrpc_svc_data d;
        int rc;
#ifndef ENABLE_PINGER
        return 0;
#endif
        ENTRY;

        LASSERT(obd_timeout > PINGER_RATE);

        if (pinger_thread != NULL)
                RETURN(-EALREADY);

        OBD_ALLOC(pinger_thread, sizeof(*pinger_thread));
        if (pinger_thread == NULL)
                RETURN(-ENOMEM);
        init_waitqueue_head(&pinger_thread->t_ctl_waitq);
        init_waitqueue_head(&suspend_timeouts_waitq);

        d.name = "ll_ping";
        d.thread = pinger_thread;

        /* CLONE_VM and CLONE_FILES just avoid a needless copy, because we
         * just drop the VM and FILES in ptlrpc_daemonize() right away. */
        rc = kernel_thread(ptlrpc_pinger_main, &d, CLONE_VM | CLONE_FILES);
        if (rc < 0) {
                CERROR("cannot start thread: %d\n", rc);
                OBD_FREE(pinger_thread, sizeof(*pinger_thread));
                RETURN(rc);
        }
        l_wait_event(pinger_thread->t_ctl_waitq,
                     pinger_thread->t_flags & SVC_RUNNING, &lwi);

        RETURN(rc);
}

int ptlrpc_stop_pinger(void)
{
        struct l_wait_info lwi = { 0 };
        int rc = 0;
#ifndef ENABLE_PINGER
        return 0;
#endif
        ENTRY;

        if (pinger_thread == NULL)
                RETURN(-EALREADY);
        down(&pinger_sem);
        pinger_thread->t_flags = SVC_STOPPING;
        wake_up(&pinger_thread->t_ctl_waitq);
        up(&pinger_sem);

        l_wait_event(pinger_thread->t_ctl_waitq,
                     (pinger_thread->t_flags & SVC_STOPPED), &lwi);

        OBD_FREE(pinger_thread, sizeof(*pinger_thread));
        pinger_thread = NULL;
        RETURN(rc);
}

void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
{
        down(&pinger_sem);
        imp->imp_next_ping = ptlrpc_next_ping(imp);
        up(&pinger_sem);
}

int ptlrpc_pinger_add_import(struct obd_import *imp)
{
        ENTRY;
        if (!list_empty(&imp->imp_pinger_chain))
                RETURN(-EALREADY);

        down(&pinger_sem);
        CDEBUG(D_HA, "adding pingable import %s->%s\n",
               imp->imp_obd->obd_uuid.uuid, imp->imp_target_uuid.uuid);
        imp->imp_next_ping = jiffies + (obd_timeout * HZ);
        /* XXX sort, blah blah */
        list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
        class_import_get(imp);

        ptlrpc_pinger_wake_up();
        up(&pinger_sem);

        RETURN(0);
}

int ptlrpc_pinger_del_import(struct obd_import *imp)
{
        ENTRY;
        if (list_empty(&imp->imp_pinger_chain))
                RETURN(-ENOENT);

        down(&pinger_sem);
        list_del_init(&imp->imp_pinger_chain);
        CDEBUG(D_HA, "removing pingable import %s->%s\n",
               imp->imp_obd->obd_uuid.uuid, imp->imp_target_uuid.uuid);
        class_import_put(imp);
        up(&pinger_sem);
        RETURN(0);
}

void ptlrpc_pinger_wake_up()
{
#ifdef ENABLE_PINGER
        pinger_thread->t_flags |= SVC_EVENT;
        wake_up(&pinger_thread->t_ctl_waitq);
#endif
}

#else /* !__KERNEL__ */

/* XXX
 * the current implementation of pinger in liblustre is not optimized
 */

static struct pinger_data {
        int             pd_recursion;
        unsigned long   pd_this_ping;
        unsigned long   pd_next_ping;
        int             pd_force_check;
} pinger_args;

static int pinger_check_rpcs(void *arg)
{
        unsigned long curtime = time(NULL);
        struct list_head *iter;
        struct pinger_data *pd = &pinger_args;

        /* prevent recursion */
        if (pd->pd_recursion++) {
                CDEBUG(D_HA, "pinger: recursion! quit\n");
                pd->pd_recursion--;
                return 0;
        }

        /* have we reached ping point? */
        if (pd->pd_next_ping > curtime && !pd->pd_force_check) {
                pd->pd_recursion--;
                return 0;
        }

        if (pd->pd_force_check)
                pd->pd_force_check = 0;

        pd->pd_this_ping = curtime;

        /* add rpcs into set */
        down(&pinger_sem);
        list_for_each(iter, &pinger_imports) {
                struct obd_import *imp =
                        list_entry(iter, struct obd_import,
                                   imp_pinger_chain);
                int level, force;
                unsigned long flags;


                spin_lock_irqsave(&imp->imp_lock, flags);
                level = imp->imp_state;
                force = imp->imp_force_verify;
                if (force)
                        imp->imp_force_verify = 0;
                spin_unlock_irqrestore(&imp->imp_lock, flags);

                if (imp->imp_next_ping <= pd->pd_this_ping || force) {
                        if (level == LUSTRE_IMP_DISCON) {
                                /* wait at least a timeout before 
                                   trying recovery again. */
                                unsigned long timeout = obd_timeout;
                                if (imp->imp_server_timeout)
                                        timeout = obd_timeout / 2;
                                imp->imp_next_ping = time(NULL) + 
                                        (timeout * HZ);
                                ptlrpc_initiate_recovery(imp);
                        } 
                        else if (level != LUSTRE_IMP_FULL ||
                                 imp->imp_obd->obd_no_recov) {
                                CDEBUG(D_HA, 
                                       "not pinging %s (in recovery "
                                       " or recovery disabled: %s)\n",
                                       imp->imp_target_uuid.uuid,
                                       ptlrpc_import_state_name(level));
                        } 
                        else if (imp->imp_pingable || force) {
                                ptlrpc_ping(imp);
                        }

                } else {
                        if (imp->imp_pingable) {
                                CDEBUG(D_HA, "don't need to ping %s "
                                       "(%lu > %lu)\n", 
                                       imp->imp_target_uuid.uuid,
                                       imp->imp_next_ping, pd->pd_this_ping);
                        }
                }
        }

        up(&pinger_sem);

        pd->pd_next_ping = pd->pd_this_ping + (obd_timeout * HZ);

        CDEBUG(D_HA, "finished a round ping\n");
        pd->pd_recursion--;
        return 0;
}

static void *pinger_callback = NULL;

int ptlrpc_start_pinger(void)
{
        memset(&pinger_args, 0, sizeof(pinger_args));
#ifdef ENABLE_PINGER
        pinger_callback =
                liblustre_register_wait_callback(&pinger_check_rpcs, &pinger_args);
#endif
        return 0;
}

int ptlrpc_stop_pinger(void)
{
#ifdef ENABLE_PINGER
        if (pinger_callback)
                liblustre_deregister_wait_callback(pinger_callback);
#endif
        return 0;
}

void ptlrpc_pinger_sending_on_import(struct obd_import *imp)
{
        down(&pinger_sem);
        imp->imp_next_ping = time(NULL) + obd_timeout;
        if (pinger_args.pd_next_ping > imp->imp_next_ping) {
                CDEBUG(D_HA, "set next ping to %ld(cur %ld)\n",
                        imp->imp_next_ping, time(NULL));
                pinger_args.pd_next_ping = imp->imp_next_ping;
        }
        up(&pinger_sem);
}

int ptlrpc_pinger_add_import(struct obd_import *imp)
{
        ENTRY;
        if (!list_empty(&imp->imp_pinger_chain))
                RETURN(-EALREADY);

        CDEBUG(D_HA, "adding pingable import %s->%s\n",
               imp->imp_obd->obd_uuid.uuid, imp->imp_target_uuid.uuid);
        ptlrpc_pinger_sending_on_import(imp);

        down(&pinger_sem);
        list_add_tail(&imp->imp_pinger_chain, &pinger_imports);
        class_import_get(imp);
        up(&pinger_sem);

        RETURN(0);
}

int ptlrpc_pinger_del_import(struct obd_import *imp)
{
        ENTRY;
        if (list_empty(&imp->imp_pinger_chain))
                RETURN(-ENOENT);

        down(&pinger_sem);
        list_del_init(&imp->imp_pinger_chain);
        CDEBUG(D_HA, "removing pingable import %s->%s\n",
               imp->imp_obd->obd_uuid.uuid, imp->imp_target_uuid.uuid);
        class_import_put(imp);
        up(&pinger_sem);
        RETURN(0);
}

void ptlrpc_pinger_wake_up()
{
        pinger_args.pd_force_check = 1;
}
#endif /* !__KERNEL__ */