/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1998
 *      Sleepycat Software.  All rights reserved.
 */

#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)db_am.c       10.15 (Sleepycat) 12/30/98";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#endif

#include "db_int.h"
#include "shqueue.h"
#include "db_page.h"
#include "db_shash.h"
#include "mp.h"
#include "btree.h"
#include "hash.h"
#include "db_am.h"
#include "db_ext.h"

static int __db_c_close __P((DBC *));
static int __db_cursor __P((DB *, DB_TXN *, DBC **, u_int32_t));
static int __db_fd __P((DB *, int *));
static int __db_get __P((DB *, DB_TXN *, DBT *, DBT *, u_int32_t));
static int __db_put __P((DB *, DB_TXN *, DBT *, DBT *, u_int32_t));

/*
 * __db_init_wrapper --
 *      Wrapper layer to implement generic DB functions.
 *
 * PUBLIC: int __db_init_wrapper __P((DB *));
 */
int
__db_init_wrapper(dbp)
        DB *dbp;
{
        dbp->close = __db_close;
        dbp->cursor = __db_cursor;
        dbp->del = NULL;                /* !!! Must be set by access method. */
        dbp->fd = __db_fd;
        dbp->get = __db_get;
        dbp->join = __db_join;
        dbp->put = __db_put;
        dbp->stat = NULL;               /* !!! Must be set by access method. */
        dbp->sync = __db_sync;

        return (0);
}

/*
 * __db_cursor --
 *      Allocate and return a cursor.
 */
static int
__db_cursor(dbp, txn, dbcp, flags)
        DB *dbp;
        DB_TXN *txn;
        DBC **dbcp;
        u_int32_t flags;
{
        DBC *dbc, *adbc;
        int ret;
        db_lockmode_t mode;
        u_int32_t op;

        DB_PANIC_CHECK(dbp);

        /* Take one from the free list if it's available. */
        DB_THREAD_LOCK(dbp);
        if ((dbc = TAILQ_FIRST(&dbp->free_queue)) != NULL)
                TAILQ_REMOVE(&dbp->free_queue, dbc, links);
        else {
                DB_THREAD_UNLOCK(dbp);

                if ((ret = __os_calloc(1, sizeof(DBC), &dbc)) != 0)
                        return (ret);

                dbc->dbp = dbp;
                dbc->c_close = __db_c_close;

                /* Set up locking information. */
                if (F_ISSET(dbp, DB_AM_LOCKING | DB_AM_CDB)) {
                        /*
                         * If we are not threaded, then there is no need to
                         * create new locker ids.  We know that no one else
                         * is running concurrently using this DB, so we can
                         * take a peek at any cursors on the active queue.
                         */
                        if (!F_ISSET(dbp, DB_AM_THREAD) &&
                            (adbc = TAILQ_FIRST(&dbp->active_queue)) != NULL)
                                dbc->lid = adbc->lid;
                        else
                                if ((ret = lock_id(dbp->dbenv->lk_info,
                                    &dbc->lid)) != 0)
                                        goto err;

                        memcpy(dbc->lock.fileid, dbp->fileid, DB_FILE_ID_LEN);
                        if (F_ISSET(dbp, DB_AM_CDB)) {
                                dbc->lock_dbt.size = DB_FILE_ID_LEN;
                                dbc->lock_dbt.data = dbc->lock.fileid;
                        } else {
                                dbc->lock_dbt.size = sizeof(dbc->lock);
                                dbc->lock_dbt.data = &dbc->lock;
                        }
                }

                switch (dbp->type) {
                case DB_BTREE:
                case DB_RECNO:
                        if ((ret = __bam_c_init(dbc)) != 0)
                                goto err;
                        break;
                case DB_HASH:
                        if ((ret = __ham_c_init(dbc)) != 0)
                                goto err;
                        break;
                default:
                        ret = EINVAL;
                        goto err;
                }

                DB_THREAD_LOCK(dbp);
        }

        if ((dbc->txn = txn) == NULL)
                dbc->locker = dbc->lid;
        else
                dbc->locker = txn->txnid;

        TAILQ_INSERT_TAIL(&dbp->active_queue, dbc, links);
        DB_THREAD_UNLOCK(dbp);

        /*
         * If this is the concurrent DB product, then we do all locking
         * in the interface, which is right here.
         */
        if (F_ISSET(dbp, DB_AM_CDB)) {
                op = LF_ISSET(DB_OPFLAGS_MASK);
                mode = (op == DB_WRITELOCK) ? DB_LOCK_WRITE :
                    (LF_ISSET(DB_RMW) ? DB_LOCK_IWRITE : DB_LOCK_READ);
                if ((ret = lock_get(dbp->dbenv->lk_info, dbc->locker, 0,
                    &dbc->lock_dbt, mode, &dbc->mylock)) != 0) {
                        (void)__db_c_close(dbc);
                        return (EAGAIN);
                }
                if (LF_ISSET(DB_RMW))
                        F_SET(dbc, DBC_RMW);
                if (op == DB_WRITELOCK)
                        F_SET(dbc, DBC_WRITER);
        }

        *dbcp = dbc;
        return (0);

err:    __os_free(dbc, sizeof(*dbc));
        return (ret);
}

/*
 * __db_c_close --
 *      Close the cursor (recycle for later use).
 */
static int
__db_c_close(dbc)
        DBC *dbc;
{
        DB *dbp;
        int ret, t_ret;

        dbp = dbc->dbp;

        DB_PANIC_CHECK(dbp);

        ret = 0;

        /*
         * We cannot release the lock until after we've called the
         * access method specific routine, since btrees may have pending
         * deletes.
         */

        /* Remove the cursor from the active queue. */
        DB_THREAD_LOCK(dbp);
        TAILQ_REMOVE(&dbp->active_queue, dbc, links);
        DB_THREAD_UNLOCK(dbp);

        /* Call the access specific cursor close routine. */
        if ((t_ret = dbc->c_am_close(dbc)) != 0 && ret == 0)
                t_ret = ret;

        /* Release the lock. */
        if (F_ISSET(dbc->dbp, DB_AM_CDB) && dbc->mylock != LOCK_INVALID) {
                ret = lock_put(dbc->dbp->dbenv->lk_info, dbc->mylock);
                dbc->mylock = LOCK_INVALID;
        }

        /* Clean up the cursor. */
        dbc->flags = 0;

#ifdef DEBUG
        /*
         * Check for leftover locks, unless we're running with transactions.
         *
         * If we're running tests, display any locks currently held.  It's
         * possible that some applications may hold locks for long periods,
         * e.g., conference room locks, but the DB tests should never close
         * holding locks.
         */
        if (F_ISSET(dbp, DB_AM_LOCKING) && dbc->lid == dbc->locker) {
                DB_LOCKREQ request;

                request.op = DB_LOCK_DUMP;
                if ((t_ret = lock_vec(dbp->dbenv->lk_info,
                    dbc->locker, 0, &request, 1, NULL)) != 0 && ret == 0)
                        ret = EAGAIN;
        }
#endif
        /* Move the cursor to the free queue. */
        DB_THREAD_LOCK(dbp);
        TAILQ_INSERT_TAIL(&dbp->free_queue, dbc, links);
        DB_THREAD_UNLOCK(dbp);

        return (ret);
}

#ifdef DEBUG
/*
 * __db_cprint --
 *      Display the current cursor list.
 *
 * PUBLIC: int __db_cprint __P((DB *));
 */
int
__db_cprint(dbp)
        DB *dbp;
{
        static const FN fn[] = {
                { DBC_RECOVER,  "recover" },
                { DBC_RMW,      "read-modify-write" },
                { 0 },
        };
        DBC *dbc;

        DB_THREAD_LOCK(dbp);
        for (dbc = TAILQ_FIRST(&dbp->active_queue);
            dbc != NULL; dbc = TAILQ_NEXT(dbc, links)) {
                fprintf(stderr,
                    "%#0x: dbp: %#0x txn: %#0x lid: %lu locker: %lu",
                    (u_int)dbc, (u_int)dbc->dbp, (u_int)dbc->txn,
                    (u_long)dbc->lid, (u_long)dbc->locker);
                __db_prflags(dbc->flags, fn, stderr);
                fprintf(stderr, "\n");
        }
        DB_THREAD_UNLOCK(dbp);

        return (0);
}
#endif /* DEBUG */

/*
 * __db_c_destroy --
 *      Destroy the cursor.
 *
 * PUBLIC: int __db_c_destroy __P((DBC *));
 */
int
__db_c_destroy(dbc)
        DBC *dbc;
{
        DB *dbp;
        int ret;

        dbp = dbc->dbp;

        /* Remove the cursor from the free queue. */
        DB_THREAD_LOCK(dbp);
        TAILQ_REMOVE(&dbp->free_queue, dbc, links);
        DB_THREAD_UNLOCK(dbp);

        /* Call the access specific cursor destroy routine. */
        ret = dbc->c_am_destroy == NULL ? 0 : dbc->c_am_destroy(dbc);

        /* Free up allocated memory. */
        if (dbc->rkey.data != NULL)
                __os_free(dbc->rkey.data, dbc->rkey.ulen);
        if (dbc->rdata.data != NULL)
                __os_free(dbc->rdata.data, dbc->rdata.ulen);
        __os_free(dbc, sizeof(*dbc));

        return (0);
}

/*
 * db_fd --
 *      Return a file descriptor for flock'ing.
 */
static int
__db_fd(dbp, fdp)
        DB *dbp;
        int *fdp;
{
        DB_PANIC_CHECK(dbp);

        /*
         * XXX
         * Truly spectacular layering violation.
         */
        return (__mp_xxx_fd(dbp->mpf, fdp));
}

/*
 * __db_get --
 *      Return a key/data pair.
 */
static int
__db_get(dbp, txn, key, data, flags)
        DB *dbp;
        DB_TXN *txn;
        DBT *key, *data;
        u_int32_t flags;
{
        DBC *dbc;
        int ret, t_ret;

        DB_PANIC_CHECK(dbp);

        if ((ret = __db_getchk(dbp, key, data, flags)) != 0)
                return (ret);

        if ((ret = dbp->cursor(dbp, txn, &dbc, 0)) != 0)
                return (ret);

        DEBUG_LREAD(dbc, txn, "__db_get", key, NULL, flags);

        ret = dbc->c_get(dbc, key, data,
            flags == 0 || flags == DB_RMW ? flags | DB_SET : flags);

        if ((t_ret = __db_c_close(dbc)) != 0 && ret == 0)
                ret = t_ret;

        return (ret);
}

/*
 * __db_put --
 *      Store a key/data pair.
 */
static int
__db_put(dbp, txn, key, data, flags)
        DB *dbp;
        DB_TXN *txn;
        DBT *key, *data;
        u_int32_t flags;
{
        DBC *dbc;
        DBT tdata;
        int ret, t_ret;

        DB_PANIC_CHECK(dbp);

        if ((ret = __db_putchk(dbp, key, data,
            flags, F_ISSET(dbp, DB_AM_RDONLY), F_ISSET(dbp, DB_AM_DUP))) != 0)
                return (ret);

        if ((ret = dbp->cursor(dbp, txn, &dbc, DB_WRITELOCK)) != 0)
                return (ret);

        DEBUG_LWRITE(dbc, txn, "__db_put", key, data, flags);

        if (flags == DB_NOOVERWRITE) {
                /*
                 * Set DB_DBT_USERMEM, this might be a threaded application and
                 * the flags checking will catch us.  We don't want the actual
                 * data, so request a partial of length 0.
                 */
                memset(&tdata, 0, sizeof(tdata));
                F_SET(&tdata, DB_DBT_USERMEM | DB_DBT_PARTIAL);
                if ((ret = dbc->c_get(dbc, key, &tdata, DB_SET | DB_RMW)) == 0)
                        ret = DB_KEYEXIST;
                else if (ret == DB_NOTFOUND)
                        ret = 0;
        }
        if (ret == 0)
                ret = dbc->c_put(dbc, key, data, DB_KEYLAST);

        if ((t_ret = __db_c_close(dbc)) != 0 && ret == 0)
                ret = t_ret;

        return (ret);
}

/*
 * __db_sync --
 *      Flush the database cache.
 *
 * PUBLIC: int __db_sync __P((DB *, u_int32_t));
 */
int
__db_sync(dbp, flags)
        DB *dbp;
        u_int32_t flags;
{
        int ret;

        DB_PANIC_CHECK(dbp);

        if ((ret = __db_syncchk(dbp, flags)) != 0)
                return (ret);

        /* If it wasn't possible to modify the file, we're done. */
        if (F_ISSET(dbp, DB_AM_INMEM | DB_AM_RDONLY))
                return (0);

        /* Flush any dirty pages from the cache to the backing file. */
        if ((ret = memp_fsync(dbp->mpf)) == DB_INCOMPLETE)
                ret = 0;

        return (ret);
}