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Sourcecode: db4.1 version File versions

mp_fopen.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996-2002
 *    Sleepycat Software.  All rights reserved.
 */
#include "db_config.h"

#ifndef lint
static const char revid[] = "$Id: mp_fopen.c,v 11.90 2002/08/26 15:22:01 bostic Exp $";
#endif /* not lint */

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

#include <string.h>
#endif

#include "db_int.h"
#include "dbinc/db_shash.h"
#include "dbinc/mp.h"

static int  __memp_fclose __P((DB_MPOOLFILE *, u_int32_t));
static int  __memp_fopen __P((DB_MPOOLFILE *,
            const char *, u_int32_t, int, size_t));
static void __memp_get_fileid __P((DB_MPOOLFILE *, u_int8_t *));
static void __memp_last_pgno __P((DB_MPOOLFILE *, db_pgno_t *));
static void __memp_refcnt __P((DB_MPOOLFILE *, db_pgno_t *));
static int  __memp_set_clear_len __P((DB_MPOOLFILE *, u_int32_t));
static int  __memp_set_fileid __P((DB_MPOOLFILE *, u_int8_t *));
static int  __memp_set_ftype __P((DB_MPOOLFILE *, int));
static int  __memp_set_lsn_offset __P((DB_MPOOLFILE *, int32_t));
static int  __memp_set_pgcookie __P((DB_MPOOLFILE *, DBT *));
static int  __memp_set_priority __P((DB_MPOOLFILE *, DB_CACHE_PRIORITY));
static void __memp_set_unlink __P((DB_MPOOLFILE *, int));

/* Initialization methods cannot be called after open is called. */
#define     MPF_ILLEGAL_AFTER_OPEN(dbmfp, name)                   \
      if (F_ISSET(dbmfp, MP_OPEN_CALLED))                   \
            return (__db_mi_open((dbmfp)->dbmp->dbenv, name, 1));

/*
 * __memp_fcreate --
 *    Create a DB_MPOOLFILE handle.
 *
 * PUBLIC: int __memp_fcreate __P((DB_ENV *, DB_MPOOLFILE **, u_int32_t));
 */
int
__memp_fcreate(dbenv, retp, flags)
      DB_ENV *dbenv;
      DB_MPOOLFILE **retp;
      u_int32_t flags;
{
      DB_MPOOL *dbmp;
      DB_MPOOLFILE *dbmfp;
      int ret;

      PANIC_CHECK(dbenv);
      ENV_REQUIRES_CONFIG(dbenv,
          dbenv->mp_handle, "memp_fcreate", DB_INIT_MPOOL);

      dbmp = dbenv->mp_handle;

      /* Validate arguments. */
      if ((ret = __db_fchk(dbenv, "memp_fcreate", flags, 0)) != 0)
            return (ret);

      /* Allocate and initialize the per-process structure. */
      if ((ret = __os_calloc(dbenv, 1, sizeof(DB_MPOOLFILE), &dbmfp)) != 0)
            return (ret);
      if ((ret = __os_calloc(dbenv, 1, sizeof(DB_FH), &dbmfp->fhp)) != 0)
            goto err;

      /* Allocate and initialize a mutex if necessary. */
      if (F_ISSET(dbenv, DB_ENV_THREAD) &&
          (ret = __db_mutex_setup(dbenv, dbmp->reginfo, &dbmfp->mutexp,
          MUTEX_ALLOC | MUTEX_THREAD)) != 0)
            goto err;

      dbmfp->ref = 1;
      dbmfp->lsn_offset = -1;
      dbmfp->dbmp = dbmp;
      dbmfp->mfp = INVALID_ROFF;

      dbmfp->close = __memp_fclose;
      dbmfp->get = __memp_fget;
      dbmfp->get_fileid = __memp_get_fileid;
      dbmfp->last_pgno = __memp_last_pgno;
      dbmfp->open = __memp_fopen;
      dbmfp->put = __memp_fput;
      dbmfp->refcnt = __memp_refcnt;
      dbmfp->set = __memp_fset;
      dbmfp->set_clear_len = __memp_set_clear_len;
      dbmfp->set_fileid = __memp_set_fileid;
      dbmfp->set_ftype = __memp_set_ftype;
      dbmfp->set_lsn_offset = __memp_set_lsn_offset;
      dbmfp->set_pgcookie = __memp_set_pgcookie;
      dbmfp->set_priority = __memp_set_priority;
      dbmfp->set_unlink = __memp_set_unlink;
      dbmfp->sync = __memp_fsync;

      *retp = dbmfp;
      return (0);

err:  if (dbmfp != NULL) {
            if (dbmfp->fhp != NULL)
                  (void)__os_free(dbenv, dbmfp->fhp);
            (void)__os_free(dbenv, dbmfp);
      }
      return (ret);
}

/*
 * __memp_set_clear_len --
 *    Set the clear length.
 */
static int
__memp_set_clear_len(dbmfp, clear_len)
      DB_MPOOLFILE *dbmfp;
      u_int32_t clear_len;
{
      MPF_ILLEGAL_AFTER_OPEN(dbmfp, "set_clear_len");

      dbmfp->clear_len = clear_len;
      return (0);
}

/*
 * __memp_set_fileid --
 *    Set the file ID.
 */
static int
__memp_set_fileid(dbmfp, fileid)
      DB_MPOOLFILE *dbmfp;
      u_int8_t *fileid;
{
      MPF_ILLEGAL_AFTER_OPEN(dbmfp, "set_fileid");

      /*
       * XXX
       * This is dangerous -- we're saving the caller's pointer instead
       * of allocating memory and copying the contents.
       */
      dbmfp->fileid = fileid;
      return (0);
}

/*
 * __memp_set_ftype --
 *    Set the file type (as registered).
 */
static int
__memp_set_ftype(dbmfp, ftype)
      DB_MPOOLFILE *dbmfp;
      int ftype;
{
      MPF_ILLEGAL_AFTER_OPEN(dbmfp, "set_ftype");

      dbmfp->ftype = ftype;
      return (0);
}

/*
 * __memp_set_lsn_offset --
 *    Set the page's LSN offset.
 */
static int
__memp_set_lsn_offset(dbmfp, lsn_offset)
      DB_MPOOLFILE *dbmfp;
      int32_t lsn_offset;
{
      MPF_ILLEGAL_AFTER_OPEN(dbmfp, "set_lsn_offset");

      dbmfp->lsn_offset = lsn_offset;
      return (0);
}

/*
 * __memp_set_pgcookie --
 *    Set the pgin/pgout cookie.
 */
static int
__memp_set_pgcookie(dbmfp, pgcookie)
      DB_MPOOLFILE *dbmfp;
      DBT *pgcookie;
{
      MPF_ILLEGAL_AFTER_OPEN(dbmfp, "set_pgcookie");

      dbmfp->pgcookie = pgcookie;
      return (0);
}

/*
 * __memp_set_priority --
 *    Set the cache priority for pages from this file.
 */
static int
__memp_set_priority(dbmfp, priority)
      DB_MPOOLFILE *dbmfp;
      DB_CACHE_PRIORITY priority;
{
      switch (priority) {
      case DB_PRIORITY_VERY_LOW:
            dbmfp->mfp->priority = MPOOL_PRI_VERY_LOW;
            break;
      case DB_PRIORITY_LOW:
            dbmfp->mfp->priority = MPOOL_PRI_LOW;
            break;
      case DB_PRIORITY_DEFAULT:
            dbmfp->mfp->priority = MPOOL_PRI_DEFAULT;
            break;
      case DB_PRIORITY_HIGH:
            dbmfp->mfp->priority = MPOOL_PRI_HIGH;
            break;
      case DB_PRIORITY_VERY_HIGH:
            dbmfp->mfp->priority = MPOOL_PRI_VERY_HIGH;
            break;
      default:
            __db_err(dbmfp->dbmp->dbenv,
                "Unknown priority value: %d", priority);
            return (EINVAL);
      }

      return (0);
}

/*
 * __memp_fopen --
 *    Open a backing file for the memory pool.
 */
static int
__memp_fopen(dbmfp, path, flags, mode, pagesize)
      DB_MPOOLFILE *dbmfp;
      const char *path;
      u_int32_t flags;
      int mode;
      size_t pagesize;
{
      DB_ENV *dbenv;
      DB_MPOOL *dbmp;
      int ret;

      dbmp = dbmfp->dbmp;
      dbenv = dbmp->dbenv;

      PANIC_CHECK(dbenv);

      /* Validate arguments. */
      if ((ret = __db_fchk(dbenv, "memp_fopen", flags,
          DB_CREATE | DB_DIRECT | DB_EXTENT |
          DB_NOMMAP | DB_ODDFILESIZE | DB_RDONLY | DB_TRUNCATE)) != 0)
            return (ret);

      /*
       * Require a non-zero, power-of-two pagesize, smaller than the
       * clear length.
       */
      if (pagesize == 0 || !POWER_OF_TWO(pagesize)) {
            __db_err(dbenv,
                "memp_fopen: page sizes must be a power-of-2");
            return (EINVAL);
      }
      if (dbmfp->clear_len > pagesize) {
            __db_err(dbenv,
                "memp_fopen: clear length larger than page size");
            return (EINVAL);
      }

      /* Read-only checks, and local flag. */
      if (LF_ISSET(DB_RDONLY) && path == NULL) {
            __db_err(dbenv,
                "memp_fopen: temporary files can't be readonly");
            return (EINVAL);
      }

      return (__memp_fopen_int(dbmfp, NULL, path, flags, mode, pagesize));
}

/*
 * __memp_fopen_int --
 *    Open a backing file for the memory pool; internal version.
 *
 * PUBLIC: int __memp_fopen_int __P((DB_MPOOLFILE *,
 * PUBLIC:     MPOOLFILE *, const char *, u_int32_t, int, size_t));
 */
int
__memp_fopen_int(dbmfp, mfp, path, flags, mode, pagesize)
      DB_MPOOLFILE *dbmfp;
      MPOOLFILE *mfp;
      const char *path;
      u_int32_t flags;
      int mode;
      size_t pagesize;
{
      DB_ENV *dbenv;
      DB_MPOOL *dbmp;
      MPOOL *mp;
      db_pgno_t last_pgno;
      size_t maxmap;
      u_int32_t mbytes, bytes, oflags;
      int mfp_alloc, ret;
      u_int8_t idbuf[DB_FILE_ID_LEN];
      char *rpath;
      void *p;

      dbmp = dbmfp->dbmp;
      dbenv = dbmp->dbenv;
      mp = dbmp->reginfo[0].primary;
      mfp_alloc = ret = 0;
      rpath = NULL;

      /*
       * Set the page size so os_open can decide whether to turn buffering
       * off if the DB_DIRECT_DB flag is set.
       */
      dbmfp->fhp->pagesize = (u_int32_t)pagesize;

      /*
       * If it's a temporary file, delay the open until we actually need
       * to write the file, and we know we can't join any existing files.
       */
      if (path == NULL)
            goto alloc;

      /*
       * Get the real name for this file and open it.  If it's a Queue extent
       * file, it may not exist, and that's OK.
       */
      oflags = 0;
      if (LF_ISSET(DB_CREATE))
            oflags |= DB_OSO_CREATE;
      if (LF_ISSET(DB_DIRECT))
            oflags |= DB_OSO_DIRECT;
      if (LF_ISSET(DB_RDONLY)) {
            F_SET(dbmfp, MP_READONLY);
            oflags |= DB_OSO_RDONLY;
      }
      if ((ret =
          __db_appname(dbenv, DB_APP_DATA, path, 0, NULL, &rpath)) != 0)
            goto err;
      if ((ret = __os_open(dbenv, rpath, oflags, mode, dbmfp->fhp)) != 0) {
            if (!LF_ISSET(DB_EXTENT))
                  __db_err(dbenv, "%s: %s", rpath, db_strerror(ret));
            goto err;
      }

      /*
       * Figure out the file's size.
       *
       * !!!
       * 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 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(
          dbenv, rpath, dbmfp->fhp, &mbytes, &bytes, NULL)) != 0) {
            __db_err(dbenv, "%s: %s", rpath, db_strerror(ret));
            goto err;
      }

      /*
       * 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 (dbmfp->fileid == NULL) {
            if ((ret = __os_fileid(dbenv, rpath, 0, idbuf)) != 0)
                  goto err;
            dbmfp->fileid = idbuf;
      }

      /*
       * If our caller knows what mfp we're using, increment the ref count,
       * no need to search.
       *
       * We don't need to acquire a lock other than the mfp itself, because
       * we know there's another reference and it's not going away.
       */
      if (mfp != NULL) {
            MUTEX_LOCK(dbenv, &mfp->mutex);
            ++mfp->mpf_cnt;
            MUTEX_UNLOCK(dbenv, &mfp->mutex);
            goto check_map;
      }

      /*
       * If not creating a temporary file, walk the list of MPOOLFILE's,
       * looking for a matching file.  Files backed by temporary files
       * or previously removed files can't match.
       *
       * DB_TRUNCATE support.
       *
       * The fileID is a filesystem unique number (e.g., a UNIX dev/inode
       * pair) plus a timestamp.  If files are removed and created in less
       * than a second, the fileID can be repeated.  The problem with
       * repetition happens when the file that previously had the fileID
       * value still has pages in the pool, since we don't want to use them
       * to satisfy requests for the new file.
       *
       * Because the DB_TRUNCATE flag reuses the dev/inode pair, repeated
       * opens with that flag set guarantees matching fileIDs when the
       * machine can open a file and then re-open with truncate within a
       * second.  For this reason, we pass that flag down, and, if we find
       * a matching entry, we ensure that it's never found again, and we
       * create a new entry for the current request.
       */
      R_LOCK(dbenv, dbmp->reginfo);
      for (mfp = SH_TAILQ_FIRST(&mp->mpfq, __mpoolfile);
          mfp != NULL; mfp = SH_TAILQ_NEXT(mfp, q, __mpoolfile)) {
            /* Skip dead files and temporary files. */
            if (F_ISSET(mfp, MP_DEADFILE | MP_TEMP))
                  continue;

            /* Skip non-matching files. */
            if (memcmp(dbmfp->fileid, R_ADDR(dbmp->reginfo,
                mfp->fileid_off), DB_FILE_ID_LEN) != 0)
                  continue;

            /*
             * If the file is being truncated, remove it from the system
             * and create a new entry.
             *
             * !!!
             * We should be able to set mfp to NULL and break out of the
             * loop, but I like the idea of checking all the entries.
             */
            if (LF_ISSET(DB_TRUNCATE)) {
                  MUTEX_LOCK(dbenv, &mfp->mutex);
                  MPOOLFILE_IGNORE(mfp);
                  MUTEX_UNLOCK(dbenv, &mfp->mutex);
                  continue;
            }

            /*
             * Some things about a file cannot be changed: the clear length,
             * page size, or lSN location.
             *
             * The file type can change if the application's pre- and post-
             * processing needs change.  For example, an application that
             * created a hash subdatabase in a database that was previously
             * all btree.
             *
             * XXX
             * We do not check to see if the pgcookie information changed,
             * or update it if it is, this might be a bug.
             */
            if (dbmfp->clear_len != mfp->clear_len ||
                pagesize != mfp->stat.st_pagesize ||
                dbmfp->lsn_offset != mfp->lsn_off) {
                  __db_err(dbenv,
                "%s: clear length, page size or LSN location changed",
                      path);
                  R_UNLOCK(dbenv, dbmp->reginfo);
                  ret = EINVAL;
                  goto err;
            }

            if (dbmfp->ftype != 0)
                  mfp->ftype = dbmfp->ftype;

            MUTEX_LOCK(dbenv, &mfp->mutex);
            ++mfp->mpf_cnt;
            MUTEX_UNLOCK(dbenv, &mfp->mutex);
            break;
      }
      R_UNLOCK(dbenv, dbmp->reginfo);

      if (mfp != NULL)
            goto check_map;

alloc:      /* Allocate and initialize a new MPOOLFILE. */
      if ((ret = __memp_alloc(
          dbmp, dbmp->reginfo, NULL, sizeof(MPOOLFILE), NULL, &mfp)) != 0)
            goto err;
      mfp_alloc = 1;
      memset(mfp, 0, sizeof(MPOOLFILE));
      mfp->mpf_cnt = 1;
      mfp->ftype = dbmfp->ftype;
      mfp->stat.st_pagesize = pagesize;
      mfp->lsn_off = dbmfp->lsn_offset;
      mfp->clear_len = dbmfp->clear_len;

      if (LF_ISSET(DB_DIRECT))
            F_SET(mfp, MP_DIRECT);
      if (LF_ISSET(DB_EXTENT))
            F_SET(mfp, MP_EXTENT);
      F_SET(mfp, MP_CAN_MMAP);

      if (path == NULL)
            F_SET(mfp, MP_TEMP);
      else {
            /*
             * 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.
             *
             * During verify or recovery, we might have to cope with a
             * truncated file; if the file size is not a multiple of the
             * page size, round down to a page, we'll take care of the
             * partial page outside the mpool system.
             */
            if (bytes % pagesize != 0) {
                  if (LF_ISSET(DB_ODDFILESIZE))
                        bytes -= (u_int32_t)(bytes % pagesize);
                  else {
                        __db_err(dbenv,
                "%s: file size not a multiple of the pagesize", rpath);
                        ret = EINVAL;
                        goto err;
                  }
            }

            /*
             * If the user specifies DB_MPOOL_LAST or DB_MPOOL_NEW on a
             * page get, we have to increment the last page in the file.
             * Figure it out and save it away.
             *
             * Note correction: page numbers are zero-based, not 1-based.
             */
            last_pgno = (db_pgno_t)(mbytes * (MEGABYTE / pagesize));
            last_pgno += (db_pgno_t)(bytes / pagesize);
            if (last_pgno != 0)
                  --last_pgno;
            mfp->orig_last_pgno = mfp->last_pgno = last_pgno;

            /* Copy the file path into shared memory. */
            if ((ret = __memp_alloc(dbmp, dbmp->reginfo,
                NULL, 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, dbmp->reginfo,
                NULL, DB_FILE_ID_LEN, &mfp->fileid_off, &p)) != 0)
                  goto err;
            memcpy(p, dbmfp->fileid, DB_FILE_ID_LEN);
      }

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

      /*
       * Prepend the MPOOLFILE to the list of MPOOLFILE's.
       */
      R_LOCK(dbenv, dbmp->reginfo);
      ret = __db_mutex_setup(dbenv, dbmp->reginfo, &mfp->mutex,
          MUTEX_NO_RLOCK);
      if (ret == 0)
            SH_TAILQ_INSERT_HEAD(&mp->mpfq, mfp, q, __mpoolfile);
      R_UNLOCK(dbenv, dbmp->reginfo);
      if (ret != 0)
            goto err;

check_map:
      /*
       * If a file:
       *    + isn't temporary
       *    + is read-only
       *    + doesn't require any pgin/pgout support
       *    + the DB_NOMMAP flag wasn't set (in either the file open or
       *      the environment in which it was opened)
       *    + 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.
       *
       * 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 (path == NULL)
                  F_CLR(mfp, MP_CAN_MMAP);
            if (!F_ISSET(dbmfp, MP_READONLY))
                  F_CLR(mfp, MP_CAN_MMAP);
            if (dbmfp->ftype != 0)
                  F_CLR(mfp, MP_CAN_MMAP);
            if (LF_ISSET(DB_NOMMAP) || F_ISSET(dbenv, DB_ENV_NOMMAP))
                  F_CLR(mfp, MP_CAN_MMAP);
            maxmap = 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 (__os_mapfile(dbenv, rpath,
                      dbmfp->fhp, dbmfp->len, 1, &dbmfp->addr) != 0) {
                        dbmfp->addr = NULL;
                        F_CLR(mfp, MP_CAN_MMAP);
                  }
            }
      }

      dbmfp->mfp = mfp;

      F_SET(dbmfp, MP_OPEN_CALLED);

      /* Add the file to the process' list of DB_MPOOLFILEs. */
      MUTEX_THREAD_LOCK(dbenv, dbmp->mutexp);
      TAILQ_INSERT_TAIL(&dbmp->dbmfq, dbmfp, q);
      MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp);

      if (0) {
err:        if (F_ISSET(dbmfp->fhp, DB_FH_VALID))
                  (void)__os_closehandle(dbenv, dbmfp->fhp);

            if (mfp_alloc) {
                  R_LOCK(dbenv, dbmp->reginfo);
                  if (mfp->path_off != 0)
                        __db_shalloc_free(dbmp->reginfo[0].addr,
                            R_ADDR(dbmp->reginfo, mfp->path_off));
                  if (mfp->fileid_off != 0)
                        __db_shalloc_free(dbmp->reginfo[0].addr,
                            R_ADDR(dbmp->reginfo, mfp->fileid_off));
                  __db_shalloc_free(dbmp->reginfo[0].addr, mfp);
                  R_UNLOCK(dbenv, dbmp->reginfo);
            }

      }
      if (rpath != NULL)
            __os_free(dbenv, rpath);
      return (ret);
}

/*
 * __memp_get_fileid --
 *    Return the file ID.
 *
 * XXX
 * Undocumented interface: DB private.
 */
static void
__memp_get_fileid(dbmfp, fidp)
      DB_MPOOLFILE *dbmfp;
      u_int8_t *fidp;
{
      /*
       * No lock needed -- we're using the handle, it had better not
       * be going away.
       *
       * !!!
       * Get the fileID out of the region, not out of the DB_MPOOLFILE
       * structure because the DB_MPOOLFILE reference is possibly short
       * lived, and isn't to be trusted.
       */
      memcpy(fidp, R_ADDR(
          dbmfp->dbmp->reginfo, dbmfp->mfp->fileid_off), DB_FILE_ID_LEN);
}

/*
 * __memp_last_pgno --
 *    Return the page number of the last page in the file.
 *
 * XXX
 * Undocumented interface: DB private.
 */
static void
__memp_last_pgno(dbmfp, pgnoaddr)
      DB_MPOOLFILE *dbmfp;
      db_pgno_t *pgnoaddr;
{
      DB_ENV *dbenv;
      DB_MPOOL *dbmp;

      dbmp = dbmfp->dbmp;
      dbenv = dbmp->dbenv;

      R_LOCK(dbenv, dbmp->reginfo);
      *pgnoaddr = dbmfp->mfp->last_pgno;
      R_UNLOCK(dbenv, dbmp->reginfo);
}

/*
 * __memp_refcnt --
 *    Return the current reference count.
 *
 * XXX
 * Undocumented interface: DB private.
 */
static void
__memp_refcnt(dbmfp, cntp)
      DB_MPOOLFILE *dbmfp;
      db_pgno_t *cntp;
{
      DB_ENV *dbenv;

      dbenv = dbmfp->dbmp->dbenv;

      MUTEX_LOCK(dbenv, &dbmfp->mfp->mutex);
      *cntp = dbmfp->mfp->mpf_cnt;
      MUTEX_UNLOCK(dbenv, &dbmfp->mfp->mutex);
}

/*
 * __memp_set_unlink --
 *    Set unlink on last close flag.
 *
 * XXX
 * Undocumented interface: DB private.
 */
static void
__memp_set_unlink(dbmpf, set)
      DB_MPOOLFILE *dbmpf;
      int set;
{
      DB_ENV *dbenv;

      dbenv = dbmpf->dbmp->dbenv;

      MUTEX_LOCK(dbenv, &dbmpf->mfp->mutex);
      if (set)
            F_SET(dbmpf->mfp, MP_UNLINK);
      else
            F_CLR(dbmpf->mfp, MP_UNLINK);
      MUTEX_UNLOCK(dbenv, &dbmpf->mfp->mutex);
}

/*
 * memp_fclose --
 *    Close a backing file for the memory pool.
 */
static int
__memp_fclose(dbmfp, flags)
      DB_MPOOLFILE *dbmfp;
      u_int32_t flags;
{
      DB_ENV *dbenv;
      int ret, t_ret;

      dbenv = dbmfp->dbmp->dbenv;

      PANIC_CHECK(dbenv);

      /*
       * XXX
       * DB_MPOOL_DISCARD: Undocumented flag: DB private.
       */
      ret = __db_fchk(dbenv, "DB_MPOOLFILE->close", flags, DB_MPOOL_DISCARD);

      if ((t_ret = __memp_fclose_int(dbmfp, flags)) != 0 && ret == 0)
            ret = t_ret;

      return (ret);
}

/*
 * __memp_fclose_int --
 *    Internal version of __memp_fclose.
 *
 * PUBLIC: int __memp_fclose_int __P((DB_MPOOLFILE *, u_int32_t));
 */
int
__memp_fclose_int(dbmfp, flags)
      DB_MPOOLFILE *dbmfp;
      u_int32_t flags;
{
      DB_ENV *dbenv;
      DB_MPOOL *dbmp;
      MPOOLFILE *mfp;
      char *rpath;
      int deleted, ret, t_ret;

      dbmp = dbmfp->dbmp;
      dbenv = dbmp->dbenv;
      ret = 0;

      /*
       * We have to reference count DB_MPOOLFILE structures as other threads
       * in the process may be using them.  Here's the problem:
       *
       * 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 any threads, and closing
       * the databases after all 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
       * find it.  We do this, rather than have the last reference holder
       * (whoever that might be) discard the DB_MPOOLFILE structure, because
       * we'd rather write error messages to the application in the close
       * routine, not in the checkpoint/sync routine.
       *
       * !!!
       * It's possible the DB_MPOOLFILE was never added to the DB_MPOOLFILE
       * file list, check the DB_OPEN_CALLED flag to be sure.
       */
      for (deleted = 0;;) {
            MUTEX_THREAD_LOCK(dbenv, dbmp->mutexp);
            if (dbmfp->ref == 1) {
                  if (F_ISSET(dbmfp, MP_OPEN_CALLED))
                        TAILQ_REMOVE(&dbmp->dbmfq, dbmfp, q);
                  deleted = 1;
            }
            MUTEX_THREAD_UNLOCK(dbenv, dbmp->mutexp);

            if (deleted)
                  break;
            __os_sleep(dbenv, 1, 0);
      }

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

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

      /* Close the file; temporary files may not yet have been created. */
      if (F_ISSET(dbmfp->fhp, DB_FH_VALID) &&
          (t_ret = __os_closehandle(dbenv, dbmfp->fhp)) != 0) {
            __db_err(dbenv, "%s: %s", __memp_fn(dbmfp), db_strerror(t_ret));
            if (ret == 0)
                  ret = t_ret;
      }

      /* Discard the thread mutex. */
      if (dbmfp->mutexp != NULL)
            __db_mutex_free(dbenv, dbmp->reginfo, dbmfp->mutexp);

      /*
       * Discard our reference on the the underlying MPOOLFILE, and close
       * it if it's no longer useful to anyone.  It possible the open of
       * the file never happened or wasn't successful, in which case, mpf
       * will be NULL;
       */
      if ((mfp = dbmfp->mfp) == NULL)
            goto done;

      /*
       * If it's a temp file, all outstanding references belong to unflushed
       * buffers.  (A temp file can only be referenced by one DB_MPOOLFILE).
       * We don't care about preserving any of those buffers, so mark the
       * MPOOLFILE as dead so that even the dirty ones just get discarded
       * when we try to flush them.
       */
      deleted = 0;
      MUTEX_LOCK(dbenv, &mfp->mutex);
      if (--mfp->mpf_cnt == 0 || LF_ISSET(DB_MPOOL_DISCARD)) {
            if (LF_ISSET(DB_MPOOL_DISCARD) ||
                F_ISSET(mfp, MP_TEMP | MP_UNLINK))
                  MPOOLFILE_IGNORE(mfp);
            if (F_ISSET(mfp, MP_UNLINK)) {
                  if ((t_ret = __db_appname(dbmp->dbenv,
                      DB_APP_DATA, R_ADDR(dbmp->reginfo,
                      mfp->path_off), 0, NULL, &rpath)) != 0 && ret == 0)
                        ret = t_ret;
                  if (t_ret == 0) {
                        if ((t_ret = __os_unlink(
                            dbmp->dbenv, rpath) != 0) && ret == 0)
                              ret = t_ret;
                        __os_free(dbenv, rpath);
                  }
            }
            if (mfp->block_cnt == 0) {
                  if ((t_ret =
                      __memp_mf_discard(dbmp, mfp)) != 0 && ret == 0)
                        ret = t_ret;
                  deleted = 1;
            }
      }
      if (deleted == 0)
            MUTEX_UNLOCK(dbenv, &mfp->mutex);

      /* Discard the DB_MPOOLFILE structure. */
done: __os_free(dbenv, dbmfp->fhp);
      __os_free(dbenv, dbmfp);

      return (ret);
}

/*
 * __memp_mf_discard --
 *    Discard an MPOOLFILE.
 *
 * PUBLIC: int __memp_mf_discard __P((DB_MPOOL *, MPOOLFILE *));
 */
int
__memp_mf_discard(dbmp, mfp)
      DB_MPOOL *dbmp;
      MPOOLFILE *mfp;
{
      DB_ENV *dbenv;
      DB_FH fh;
      DB_MPOOL_STAT *sp;
      MPOOL *mp;
      char *rpath;
      int ret;

      dbenv = dbmp->dbenv;
      mp = dbmp->reginfo[0].primary;
      ret = 0;

      /*
       * Expects caller to be holding the MPOOLFILE mutex.
       *
       * When discarding a file, we have to flush writes from it to disk.
       * The scenario is that dirty buffers from this file need to be
       * flushed to satisfy a future checkpoint, but when the checkpoint
       * calls mpool sync, the sync code won't know anything about them.
       */
      if (!F_ISSET(mfp, MP_DEADFILE) &&
          (ret = __db_appname(dbenv, DB_APP_DATA,
          R_ADDR(dbmp->reginfo, mfp->path_off), 0, NULL, &rpath)) == 0) {
            if ((ret = __os_open(dbenv, rpath, 0, 0, &fh)) == 0) {
                  ret = __os_fsync(dbenv, &fh);
                  (void)__os_closehandle(dbenv, &fh);
            }
            __os_free(dbenv, rpath);
      }

      /*
       * We have to release the MPOOLFILE lock before acquiring the region
       * lock so that we don't deadlock.  Make sure nobody ever looks at
       * this structure again.
       */
      MPOOLFILE_IGNORE(mfp);

      /* Discard the mutex we're holding. */
      MUTEX_UNLOCK(dbenv, &mfp->mutex);

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

      /* Copy the statistics into the region. */
      sp = &mp->stat;
      sp->st_cache_hit += mfp->stat.st_cache_hit;
      sp->st_cache_miss += mfp->stat.st_cache_miss;
      sp->st_map += mfp->stat.st_map;
      sp->st_page_create += mfp->stat.st_page_create;
      sp->st_page_in += mfp->stat.st_page_in;
      sp->st_page_out += mfp->stat.st_page_out;

      /* Clear the mutex this MPOOLFILE recorded. */
      __db_shlocks_clear(&mfp->mutex, dbmp->reginfo,
          (REGMAINT *)R_ADDR(dbmp->reginfo, mp->maint_off));

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

      R_UNLOCK(dbenv, dbmp->reginfo);

      return (ret);
}

/*
 * __memp_fn --
 *    On errors we print whatever is available as the file name.
 *
 * PUBLIC: char * __memp_fn __P((DB_MPOOLFILE *));
 */
char *
__memp_fn(dbmfp)
      DB_MPOOLFILE *dbmfp;
{
      return (__memp_fns(dbmfp->dbmp, dbmfp->mfp));
}

/*
 * __memp_fns --
 *    On errors we print whatever is available as the file name.
 *
 * PUBLIC: char * __memp_fns __P((DB_MPOOL *, MPOOLFILE *));
 *
 */
char *
__memp_fns(dbmp, mfp)
      DB_MPOOL *dbmp;
      MPOOLFILE *mfp;
{
      if (mfp->path_off == 0)
            return ((char *)"temporary");

      return ((char *)R_ADDR(dbmp->reginfo, mfp->path_off));
}

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