/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *      Sleepycat Software.  All rights reserved.
 */
#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)mp_fopen.c    10.60 (Sleepycat) 1/1/99";
#endif /* not lint */

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

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

#include "db_int.h"
#include "shqueue.h"
#include "db_shash.h"
#include "mp.h"
#include "common_ext.h"

static int __memp_mf_close __P((DB_MPOOL *, DB_MPOOLFILE *));
static int __memp_mf_open __P((DB_MPOOL *,
    const char *, size_t, db_pgno_t, DB_MPOOL_FINFO *, MPOOLFILE **));

/*
 * memp_fopen --
 *      Open a backing file for the memory pool.
 */
int
memp_fopen(dbmp, path, flags, mode, pagesize, finfop, retp)
        DB_MPOOL *dbmp;
        const char *path;
        u_int32_t flags;
        int mode;
        size_t pagesize;
        DB_MPOOL_FINFO *finfop;
        DB_MPOOLFILE **retp;
{
        int ret;

        MP_PANIC_CHECK(dbmp);

        /* Validate arguments. */
        if ((ret = __db_fchk(dbmp->dbenv,
            "memp_fopen", flags, DB_CREATE | DB_NOMMAP | DB_RDONLY)) != 0)
                return (ret);

        /* Require a non-zero pagesize. */
        if (pagesize == 0) {
                __db_err(dbmp->dbenv, "memp_fopen: pagesize not specified");
                return (EINVAL);
        }
        if (finfop != NULL && finfop->clear_len > pagesize)
                return (EINVAL);

        return (__memp_fopen(dbmp,
            NULL, path, flags, mode, pagesize, 1, finfop, retp));
}

/*
 * __memp_fopen --
 *      Open a backing file for the memory pool; internal version.
 *
 * PUBLIC: int __memp_fopen __P((DB_MPOOL *, MPOOLFILE *, const char *,
 * PUBLIC:    u_int32_t, int, size_t, int, DB_MPOOL_FINFO *, DB_MPOOLFILE **));
 */
int
__memp_fopen(dbmp, mfp, path, flags, mode, pagesize, needlock, finfop, retp)
        DB_MPOOL *dbmp;
        MPOOLFILE *mfp;
        const char *path;
        u_int32_t flags;
        int mode, needlock;
        size_t pagesize;
        DB_MPOOL_FINFO *finfop;
        DB_MPOOLFILE **retp;
{
        DB_ENV *dbenv;
        DB_MPOOLFILE *dbmfp;
        DB_MPOOL_FINFO finfo;
        db_pgno_t last_pgno;
        size_t maxmap;
        u_int32_t mbytes, bytes;
        int ret;
        u_int8_t idbuf[DB_FILE_ID_LEN];
        char *rpath;

        dbenv = dbmp->dbenv;
        ret = 0;
        rpath = NULL;

        /*
         * If mfp is provided, we take the DB_MPOOL_FINFO information from
         * the mfp.  We don't bother initializing everything, because some
         * of them are expensive to acquire.  If no mfp is provided and the
         * finfop argument is NULL, we default the values.
         */
        if (finfop == NULL) {
                memset(&finfo, 0, sizeof(finfo));
                if (mfp != NULL) {
                        finfo.ftype = mfp->ftype;
                        finfo.pgcookie = NULL;
                        finfo.fileid = NULL;
                        finfo.lsn_offset = mfp->lsn_off;
                        finfo.clear_len = mfp->clear_len;
                } else {
                        finfo.ftype = 0;
                        finfo.pgcookie = NULL;
                        finfo.fileid = NULL;
                        finfo.lsn_offset = -1;
                        finfo.clear_len = 0;
                }
                finfop = &finfo;
        }

        /* Allocate and initialize the per-process structure. */
        if ((ret = __os_calloc(1, sizeof(DB_MPOOLFILE), &dbmfp)) != 0)
                return (ret);
        dbmfp->dbmp = dbmp;
        dbmfp->fd = -1;
        dbmfp->ref = 1;
        if (LF_ISSET(DB_RDONLY))
                F_SET(dbmfp, MP_READONLY);

        if (path == NULL) {
                if (LF_ISSET(DB_RDONLY)) {
                        __db_err(dbenv,
                            "memp_fopen: temporary files can't be readonly");
                        ret = EINVAL;
                        goto err;
                }
                last_pgno = 0;
        } else {
                /* Get the real name for this file and open it. */
                if ((ret = __db_appname(dbenv,
                    DB_APP_DATA, NULL, path, 0, NULL, &rpath)) != 0)
                        goto err;
                if ((ret = __db_open(rpath,
                   LF_ISSET(DB_CREATE | DB_RDONLY),
                   DB_CREATE | DB_RDONLY, mode, &dbmfp->fd)) != 0) {
                        __db_err(dbenv, "%s: %s", rpath, strerror(ret));
                        goto err;
                }

                /*
                 * Don't permit files that aren't a multiple of the pagesize,
                 * and find the number of the last page in the file, all the
                 * time being careful not to overflow 32 bits.
                 *
                 * !!!
                 * We can't use off_t's here, or in any code in the mainline
                 * library for that matter.  (We have to use them in the os
                 * stubs, of course, as there are system calls that take them
                 * as arguments.)  The reason is that some customers build in
                 * environments where an off_t is 32-bits, but still run where
                 * offsets are 64-bits, and they pay us a lot of money.
                 */
                if ((ret = __os_ioinfo(rpath,
                    dbmfp->fd, &mbytes, &bytes, NULL)) != 0) {
                        __db_err(dbenv, "%s: %s", rpath, strerror(ret));
                        goto err;
                }

                /* Page sizes have to be a power-of-two, ignore mbytes. */
                if (bytes % pagesize != 0) {
                        __db_err(dbenv,
                            "%s: file size not a multiple of the pagesize",
                            rpath);
                        ret = EINVAL;
                        goto err;
                }

                last_pgno = mbytes * (MEGABYTE / pagesize);
                last_pgno += bytes / pagesize;

                /* Correction: page numbers are zero-based, not 1-based. */
                if (last_pgno != 0)
                        --last_pgno;

                /*
                 * Get the file id if we weren't given one.  Generated file id's
                 * don't use timestamps, otherwise there'd be no chance of any
                 * other process joining the party.
                 */
                if (finfop->fileid == NULL) {
                        if ((ret = __os_fileid(dbenv, rpath, 0, idbuf)) != 0)
                                goto err;
                        finfop->fileid = idbuf;
                }
        }

        /*
         * If we weren't provided an underlying shared object to join with,
         * find/allocate the shared file objects.  Also allocate space for
         * for the per-process thread lock.
         */
        if (needlock)
                LOCKREGION(dbmp);

        if (mfp == NULL)
                ret = __memp_mf_open(dbmp,
                    path, pagesize, last_pgno, finfop, &mfp);
        else {
                ++mfp->ref;
                ret = 0;
        }
        if (ret == 0 &&
            F_ISSET(dbmp, MP_LOCKHANDLE) && (ret =
            __memp_alloc(dbmp, sizeof(db_mutex_t), NULL, &dbmfp->mutexp)) == 0)
                LOCKINIT(dbmp, dbmfp->mutexp);

        if (needlock)
                UNLOCKREGION(dbmp);
        if (ret != 0)
                goto err;

        dbmfp->mfp = mfp;

        /*
         * If a file:
         *      + is read-only
         *      + isn't temporary
         *      + doesn't require any pgin/pgout support
         *      + the DB_NOMMAP flag wasn't set
         *      + and is less than mp_mmapsize bytes in size
         *
         * we can mmap it instead of reading/writing buffers.  Don't do error
         * checking based on the mmap call failure.  We want to do normal I/O
         * on the file if the reason we failed was because the file was on an
         * NFS mounted partition, and we can fail in buffer I/O just as easily
         * as here.
         *
         * XXX
         * We'd like to test to see if the file is too big to mmap.  Since we
         * don't know what size or type off_t's or size_t's are, or the largest
         * unsigned integral type is, or what random insanity the local C
         * compiler will perpetrate, doing the comparison in a portable way is
         * flatly impossible.  Hope that mmap fails if the file is too large.
         */
#define DB_MAXMMAPSIZE  (10 * 1024 * 1024)      /* 10 Mb. */
        if (F_ISSET(mfp, MP_CAN_MMAP)) {
                if (!F_ISSET(dbmfp, MP_READONLY))
                        F_CLR(mfp, MP_CAN_MMAP);
                if (path == NULL)
                        F_CLR(mfp, MP_CAN_MMAP);
                if (finfop->ftype != 0)
                        F_CLR(mfp, MP_CAN_MMAP);
                if (LF_ISSET(DB_NOMMAP))
                        F_CLR(mfp, MP_CAN_MMAP);
                maxmap = dbenv == NULL || dbenv->mp_mmapsize == 0 ?
                    DB_MAXMMAPSIZE : dbenv->mp_mmapsize;
                if (mbytes > maxmap / MEGABYTE ||
                    (mbytes == maxmap / MEGABYTE && bytes >= maxmap % MEGABYTE))
                        F_CLR(mfp, MP_CAN_MMAP);
        }
        dbmfp->addr = NULL;
        if (F_ISSET(mfp, MP_CAN_MMAP)) {
                dbmfp->len = (size_t)mbytes * MEGABYTE + bytes;
                if (__db_mapfile(rpath,
                    dbmfp->fd, dbmfp->len, 1, &dbmfp->addr) != 0) {
                        dbmfp->addr = NULL;
                        F_CLR(mfp, MP_CAN_MMAP);
                }
        }
        if (rpath != NULL)
                __os_freestr(rpath);

        LOCKHANDLE(dbmp, dbmp->mutexp);
        TAILQ_INSERT_TAIL(&dbmp->dbmfq, dbmfp, q);
        UNLOCKHANDLE(dbmp, dbmp->mutexp);

        *retp = dbmfp;
        return (0);

err:    /*
         * Note that we do not have to free the thread mutex, because we
         * never get to here after we have successfully allocated it.
         */
        if (rpath != NULL)
                __os_freestr(rpath);
        if (dbmfp->fd != -1)
                (void)__os_close(dbmfp->fd);
        if (dbmfp != NULL)
                __os_free(dbmfp, sizeof(DB_MPOOLFILE));
        return (ret);
}

/*
 * __memp_mf_open --
 *      Open an MPOOLFILE.
 */
static int
__memp_mf_open(dbmp, path, pagesize, last_pgno, finfop, retp)
        DB_MPOOL *dbmp;
        const char *path;
        size_t pagesize;
        db_pgno_t last_pgno;
        DB_MPOOL_FINFO *finfop;
        MPOOLFILE **retp;
{
        MPOOLFILE *mfp;
        int ret;
        void *p;

#define ISTEMPORARY     (path == NULL)

        /*
         * Walk the list of MPOOLFILE's, looking for a matching file.
         * Temporary files can't match previous files.
         */
        if (!ISTEMPORARY)
                for (mfp = SH_TAILQ_FIRST(&dbmp->mp->mpfq, __mpoolfile);
                    mfp != NULL; mfp = SH_TAILQ_NEXT(mfp, q, __mpoolfile)) {
                        if (F_ISSET(mfp, MP_TEMP))
                                continue;
                        if (!memcmp(finfop->fileid,
                            R_ADDR(dbmp, mfp->fileid_off), DB_FILE_ID_LEN)) {
                                if (finfop->clear_len != mfp->clear_len ||
                                    finfop->ftype != mfp->ftype ||
                                    pagesize != mfp->stat.st_pagesize) {
                                        __db_err(dbmp->dbenv,
                            "%s: ftype, clear length or pagesize changed",
                                            path);
                                        return (EINVAL);
                                }

                                /* Found it: increment the reference count. */
                                ++mfp->ref;
                                *retp = mfp;
                                return (0);
                        }
                }

        /* Allocate a new MPOOLFILE. */
        if ((ret = __memp_alloc(dbmp, sizeof(MPOOLFILE), NULL, &mfp)) != 0)
                return (ret);
        *retp = mfp;

        /* Initialize the structure. */
        memset(mfp, 0, sizeof(MPOOLFILE));
        mfp->ref = 1;
        mfp->ftype = finfop->ftype;
        mfp->lsn_off = finfop->lsn_offset;
        mfp->clear_len = finfop->clear_len;

        /*
         * If the user specifies DB_MPOOL_LAST or DB_MPOOL_NEW on a memp_fget,
         * we have to know the last page in the file.  Figure it out and save
         * it away.
         */
        mfp->stat.st_pagesize = pagesize;
        mfp->orig_last_pgno = mfp->last_pgno = last_pgno;

        if (ISTEMPORARY)
                F_SET(mfp, MP_TEMP);
        else {
                /* Copy the file path into shared memory. */
                if ((ret = __memp_alloc(dbmp,
                    strlen(path) + 1, &mfp->path_off, &p)) != 0)
                        goto err;
                memcpy(p, path, strlen(path) + 1);

                /* Copy the file identification string into shared memory. */
                if ((ret = __memp_alloc(dbmp,
                    DB_FILE_ID_LEN, &mfp->fileid_off, &p)) != 0)
                        goto err;
                memcpy(p, finfop->fileid, DB_FILE_ID_LEN);

                F_SET(mfp, MP_CAN_MMAP);
        }

        /* Copy the page cookie into shared memory. */
        if (finfop->pgcookie == NULL || finfop->pgcookie->size == 0) {
                mfp->pgcookie_len = 0;
                mfp->pgcookie_off = 0;
        } else {
                if ((ret = __memp_alloc(dbmp,
                    finfop->pgcookie->size, &mfp->pgcookie_off, &p)) != 0)
                        goto err;
                memcpy(p, finfop->pgcookie->data, finfop->pgcookie->size);
                mfp->pgcookie_len = finfop->pgcookie->size;
        }

        /* Prepend the MPOOLFILE to the list of MPOOLFILE's. */
        SH_TAILQ_INSERT_HEAD(&dbmp->mp->mpfq, mfp, q, __mpoolfile);

        if (0) {
err:            if (mfp->path_off != 0)
                        __db_shalloc_free(dbmp->addr,
                            R_ADDR(dbmp, mfp->path_off));
                if (mfp->fileid_off != 0)
                        __db_shalloc_free(dbmp->addr,
                            R_ADDR(dbmp, mfp->fileid_off));
                if (mfp != NULL)
                        __db_shalloc_free(dbmp->addr, mfp);
                mfp = NULL;
        }
        return (0);
}

/*
 * memp_fclose --
 *      Close a backing file for the memory pool.
 */
int
memp_fclose(dbmfp)
        DB_MPOOLFILE *dbmfp;
{
        DB_MPOOL *dbmp;
        int ret, t_ret;

        dbmp = dbmfp->dbmp;
        ret = 0;

        MP_PANIC_CHECK(dbmp);

        for (;;) {
                LOCKHANDLE(dbmp, dbmp->mutexp);

                /*
                 * We have to reference count DB_MPOOLFILE structures as other
                 * threads may be using them.  The problem only happens if the
                 * application makes a bad design choice.  Here's the path:
                 *
                 * Thread A opens a database.
                 * Thread B uses thread A's DB_MPOOLFILE to write a buffer
                 *    in order to free up memory in the mpool cache.
                 * Thread A closes the database while thread B is using the
                 *    DB_MPOOLFILE structure.
                 *
                 * By opening all databases before creating the threads, and
                 * closing them after the threads have exited, applications
                 * get better performance and avoid the problem path entirely.
                 *
                 * Regardless, holding the DB_MPOOLFILE to flush a dirty buffer
                 * is a short-term lock, even in worst case, since we better be
                 * the only thread of control using the DB_MPOOLFILE structure
                 * to read pages *into* the cache.  Wait until we're the only
                 * reference holder and remove the DB_MPOOLFILE structure from
                 * the list, so nobody else can even find it.
                 */
                if (dbmfp->ref == 1) {
                        TAILQ_REMOVE(&dbmp->dbmfq, dbmfp, q);
                        break;
                }
                UNLOCKHANDLE(dbmp, dbmp->mutexp);

                (void)__os_sleep(1, 0);
        }
        UNLOCKHANDLE(dbmp, dbmp->mutexp);

        /* Complain if pinned blocks never returned. */
        if (dbmfp->pinref != 0)
                __db_err(dbmp->dbenv, "%s: close: %lu blocks left pinned",
                    __memp_fn(dbmfp), (u_long)dbmfp->pinref);

        /* Close the underlying MPOOLFILE. */
        (void)__memp_mf_close(dbmp, dbmfp);

        /* Discard any mmap information. */
        if (dbmfp->addr != NULL &&
            (ret = __db_unmapfile(dbmfp->addr, dbmfp->len)) != 0)
                __db_err(dbmp->dbenv,
                    "%s: %s", __memp_fn(dbmfp), strerror(ret));

        /* Close the file; temporary files may not yet have been created. */
        if (dbmfp->fd != -1 && (t_ret = __os_close(dbmfp->fd)) != 0) {
                __db_err(dbmp->dbenv,
                    "%s: %s", __memp_fn(dbmfp), strerror(t_ret));
                if (ret != 0)
                        t_ret = ret;
        }

        /* Free memory. */
        if (dbmfp->mutexp != NULL) {
                LOCKREGION(dbmp);
                __db_shalloc_free(dbmp->addr, dbmfp->mutexp);
                UNLOCKREGION(dbmp);
        }

        /* Discard the DB_MPOOLFILE structure. */
        __os_free(dbmfp, sizeof(DB_MPOOLFILE));

        return (ret);
}

/*
 * __memp_mf_close --
 *      Close down an MPOOLFILE.
 */
static int
__memp_mf_close(dbmp, dbmfp)
        DB_MPOOL *dbmp;
        DB_MPOOLFILE *dbmfp;
{
        BH *bhp, *nbhp;
        MPOOL *mp;
        MPOOLFILE *mfp;
        size_t mf_offset;

        mp = dbmp->mp;
        mfp = dbmfp->mfp;

        LOCKREGION(dbmp);

        /* If more than a single reference, simply decrement. */
        if (mfp->ref > 1) {
                --mfp->ref;
                goto ret1;
        }

        /*
         * Move any BH's held by the file to the free list.  We don't free the
         * memory itself because we may be discarding the memory pool, and it's
         * fairly expensive to reintegrate the buffers back into the region for
         * no purpose.
         */
        mf_offset = R_OFFSET(dbmp, mfp);
        for (bhp = SH_TAILQ_FIRST(&mp->bhq, __bh); bhp != NULL; bhp = nbhp) {
                nbhp = SH_TAILQ_NEXT(bhp, q, __bh);

#ifdef DEBUG_NO_DIRTY
                /* Complain if we find any blocks that were left dirty. */
                if (F_ISSET(bhp, BH_DIRTY))
                        __db_err(dbmp->dbenv,
                            "%s: close: pgno %lu left dirty; ref %lu",
                            __memp_fn(dbmfp),
                            (u_long)bhp->pgno, (u_long)bhp->ref);
#endif

                if (bhp->mf_offset == mf_offset) {
                        if (F_ISSET(bhp, BH_DIRTY)) {
                                ++mp->stat.st_page_clean;
                                --mp->stat.st_page_dirty;
                        }
                        __memp_bhfree(dbmp, mfp, bhp, 0);
                        SH_TAILQ_INSERT_HEAD(&mp->bhfq, bhp, q, __bh);
                }
        }

        /* Delete from the list of MPOOLFILEs. */
        SH_TAILQ_REMOVE(&mp->mpfq, mfp, q, __mpoolfile);

        /* Free the space. */
        if (mfp->path_off != 0)
                __db_shalloc_free(dbmp->addr, R_ADDR(dbmp, mfp->path_off));
        if (mfp->fileid_off != 0)
                __db_shalloc_free(dbmp->addr, R_ADDR(dbmp, mfp->fileid_off));
        if (mfp->pgcookie_off != 0)
                __db_shalloc_free(dbmp->addr, R_ADDR(dbmp, mfp->pgcookie_off));
        __db_shalloc_free(dbmp->addr, mfp);

ret1:   UNLOCKREGION(dbmp);
        return (0);
}