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log.c

/*-
 * 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[] = "@(#)log.c   10.63 (Sleepycat) 10/10/98";
#endif /* not lint */

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

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

#include "db_int.h"
#include "shqueue.h"
#include "log.h"
#include "db_dispatch.h"
#include "txn.h"
#include "txn_auto.h"
#include "common_ext.h"

static int __log_recover __P((DB_LOG *));

/*
 * log_open --
 *    Initialize and/or join a log.
 */
int
log_open(path, flags, mode, dbenv, lpp)
      const char *path;
      u_int32_t flags;
      int mode;
      DB_ENV *dbenv;
      DB_LOG **lpp;
{
      DB_LOG *dblp;
      LOG *lp;
      int ret;

      /* Validate arguments. */
#ifdef HAVE_SPINLOCKS
#define     OKFLAGS     (DB_CREATE | DB_THREAD)
#else
#define     OKFLAGS     (DB_CREATE)
#endif
      if ((ret = __db_fchk(dbenv, "log_open", flags, OKFLAGS)) != 0)
            return (ret);

      /* Create and initialize the DB_LOG structure. */
      if ((ret = __os_calloc(1, sizeof(DB_LOG), &dblp)) != 0)
            return (ret);

      if (path != NULL && (ret = __os_strdup(path, &dblp->dir)) != 0)
            goto err;

      dblp->dbenv = dbenv;
      dblp->lfd = -1;
      ZERO_LSN(dblp->c_lsn);
      dblp->c_fd = -1;

      /*
       * The log region isn't fixed size because we store the registered
       * file names there.  Make it fairly large so that we don't have to
       * grow it.
       */
#define     DEF_LOG_SIZE      (30 * 1024)

      /* Map in the region. */
      dblp->reginfo.dbenv = dbenv;
      dblp->reginfo.appname = DB_APP_LOG;
      if (path == NULL)
            dblp->reginfo.path = NULL;
      else
            if ((ret = __os_strdup(path, &dblp->reginfo.path)) != 0)
                  goto err;
      dblp->reginfo.file = DB_DEFAULT_LOG_FILE;
      dblp->reginfo.mode = mode;
      dblp->reginfo.size = DEF_LOG_SIZE;
      dblp->reginfo.dbflags = flags;
      dblp->reginfo.flags = REGION_SIZEDEF;
      if ((ret = __db_rattach(&dblp->reginfo)) != 0)
            goto err;

      /*
       * The LOG structure is first in the region, the rest of the region
       * is free space.
       */
      dblp->lp = dblp->reginfo.addr;
      dblp->addr = (u_int8_t *)dblp->lp + sizeof(LOG);

      /* Initialize a created region. */
      if (F_ISSET(&dblp->reginfo, REGION_CREATED)) {
            __db_shalloc_init(dblp->addr, DEF_LOG_SIZE - sizeof(LOG));

            /* Initialize the LOG structure. */
            lp = dblp->lp;
            lp->persist.lg_max = dbenv == NULL ? 0 : dbenv->lg_max;
            if (lp->persist.lg_max == 0)
                  lp->persist.lg_max = DEFAULT_MAX;
            lp->persist.magic = DB_LOGMAGIC;
            lp->persist.version = DB_LOGVERSION;
            lp->persist.mode = mode;
            SH_TAILQ_INIT(&lp->fq);

            /* Initialize LOG LSNs. */
            lp->lsn.file = 1;
            lp->lsn.offset = 0;
      }

      /* Initialize thread information, mutex. */
      if (LF_ISSET(DB_THREAD)) {
            F_SET(dblp, DB_AM_THREAD);
            if ((ret = __db_shalloc(dblp->addr,
                sizeof(db_mutex_t), MUTEX_ALIGNMENT, &dblp->mutexp)) != 0)
                  goto err;
            (void)__db_mutex_init(dblp->mutexp, 0);
      }

      /*
       * If doing recovery, try and recover any previous log files before
       * releasing the lock.
       */
      if (F_ISSET(&dblp->reginfo, REGION_CREATED) &&
          (ret = __log_recover(dblp)) != 0)
            goto err;

      UNLOCK_LOGREGION(dblp);
      *lpp = dblp;
      return (0);

err:  if (dblp->reginfo.addr != NULL) {
            if (dblp->mutexp != NULL)
                  __db_shalloc_free(dblp->addr, dblp->mutexp);

            UNLOCK_LOGREGION(dblp);
            (void)__db_rdetach(&dblp->reginfo);
            if (F_ISSET(&dblp->reginfo, REGION_CREATED))
                  (void)log_unlink(path, 1, dbenv);
      }

      if (dblp->reginfo.path != NULL)
            __os_freestr(dblp->reginfo.path);
      if (dblp->dir != NULL)
            __os_freestr(dblp->dir);
      __os_free(dblp, sizeof(*dblp));
      return (ret);
}

/*
 * __log_panic --
 *    Panic a log.
 *
 * PUBLIC: void __log_panic __P((DB_ENV *));
 */
void
__log_panic(dbenv)
      DB_ENV *dbenv;
{
      if (dbenv->lg_info != NULL)
            dbenv->lg_info->lp->rlayout.panic = 1;
}

/*
 * __log_recover --
 *    Recover a log.
 */
static int
__log_recover(dblp)
      DB_LOG *dblp;
{
      DBT dbt;
      DB_LSN lsn;
      LOG *lp;
      u_int32_t chk;
      int cnt, found_checkpoint, ret;

      lp = dblp->lp;

      /*
       * Find a log file.  If none exist, we simply return, leaving
       * everything initialized to a new log.
       */
      if ((ret = __log_find(dblp, 0, &cnt)) != 0)
            return (ret);
      if (cnt == 0)
            return (0);

      /*
       * We have the last useful log file and we've loaded any persistent
       * information.  Pretend that the log is larger than it can possibly
       * be, and read the last file, looking for the last checkpoint and
       * the log's end.
       */
      lp->lsn.file = cnt + 1;
      lp->lsn.offset = 0;
      lsn.file = cnt;
      lsn.offset = 0;

      /* Set the cursor.  Shouldn't fail, leave error messages on. */
      memset(&dbt, 0, sizeof(dbt));
      if ((ret = __log_get(dblp, &lsn, &dbt, DB_SET, 0)) != 0)
            return (ret);

      /*
       * Read to the end of the file, saving checkpoints.  This will fail
       * at some point, so turn off error messages.
       */
      found_checkpoint = 0;
      while (__log_get(dblp, &lsn, &dbt, DB_NEXT, 1) == 0) {
            if (dbt.size < sizeof(u_int32_t))
                  continue;
            memcpy(&chk, dbt.data, sizeof(u_int32_t));
            if (chk == DB_txn_ckp) {
                  lp->chkpt_lsn = lsn;
                  found_checkpoint = 1;
            }
      }

      /*
       * We now know where the end of the log is.  Set the first LSN that
       * we want to return to an application and the LSN of the last known
       * record on disk.
       */
      lp->lsn = lp->s_lsn = lsn;
      lp->lsn.offset += dblp->c_len;

      /* Set up the current buffer information, too. */
      lp->len = dblp->c_len;
      lp->b_off = 0;
      lp->w_off = lp->lsn.offset;

      /*
       * It's possible that we didn't find a checkpoint because there wasn't
       * one in the last log file.  Start searching.
       */
      while (!found_checkpoint && cnt > 1) {
            lsn.file = --cnt;
            lsn.offset = 0;

            /* Set the cursor.  Shouldn't fail, leave error messages on. */
            if ((ret = __log_get(dblp, &lsn, &dbt, DB_SET, 0)) != 0)
                  return (ret);

            /*
             * Read to the end of the file, saving checkpoints.  Shouldn't
             * fail, leave error messages on.
             */
            while (__log_get(dblp, &lsn, &dbt, DB_NEXT, 0) == 0) {
                  if (dbt.size < sizeof(u_int32_t))
                        continue;
                  memcpy(&chk, dbt.data, sizeof(u_int32_t));
                  if (chk == DB_txn_ckp) {
                        lp->chkpt_lsn = lsn;
                        found_checkpoint = 1;
                  }
            }
      }
      /*
       * Reset the cursor lsn to the beginning of the log, so that an
       * initial call to DB_NEXT does the right thing.
       */
      ZERO_LSN(dblp->c_lsn);

      /* If we never find a checkpoint, that's okay, just 0 it out. */
      if (!found_checkpoint)
            ZERO_LSN(lp->chkpt_lsn);

      /*
       * !!!
       * The test suite explicitly looks for this string -- don't change
       * it here unless you also change it there.
       */
      __db_err(dblp->dbenv,
          "Finding last valid log LSN: file: %lu offset %lu",
          (u_long)lp->lsn.file, (u_long)lp->lsn.offset);

      return (0);
}

/*
 * __log_find --
 *    Try to find a log file.  If find_first is set, valp will contain
 * the number of the first log file, else it will contain the number of
 * the last log file.
 *
 * PUBLIC: int __log_find __P((DB_LOG *, int, int *));
 */
int
__log_find(dblp, find_first, valp)
      DB_LOG *dblp;
      int find_first, *valp;
{
      u_int32_t clv, logval;
      int cnt, fcnt, ret;
      const char *dir;
      char **names, *p, *q;

      *valp = 0;

      /* Find the directory name. */
      if ((ret = __log_name(dblp, 1, &p, NULL, 0)) != 0)
            return (ret);
      if ((q = __db_rpath(p)) == NULL)
            dir = PATH_DOT;
      else {
            *q = '\0';
            dir = p;
      }

      /* Get the list of file names. */
      ret = __os_dirlist(dir, &names, &fcnt);
      __os_freestr(p);
      if (ret != 0) {
            __db_err(dblp->dbenv, "%s: %s", dir, strerror(ret));
            return (ret);
      }

      /*
       * Search for a valid log file name, return a value of 0 on
       * failure.
       *
       * XXX
       * Assumes that atoi(3) returns a 32-bit number.
       */
      for (cnt = fcnt, clv = logval = 0; --cnt >= 0;) {
            if (strncmp(names[cnt], LFPREFIX, sizeof(LFPREFIX) - 1) != 0)
                  continue;

            clv = atoi(names[cnt] + (sizeof(LFPREFIX) - 1));
            if (find_first) {
                  if (logval != 0 && clv > logval)
                        continue;
            } else
                  if (logval != 0 && clv < logval)
                        continue;

            if (__log_valid(dblp, clv, 1) == 0)
                  logval = clv;
      }

      *valp = logval;

      /* Discard the list. */
      __os_dirfree(names, fcnt);

      return (0);
}

/*
 * log_valid --
 *    Validate a log file.
 *
 * PUBLIC: int __log_valid __P((DB_LOG *, u_int32_t, int));
 */
int
__log_valid(dblp, number, set_persist)
      DB_LOG *dblp;
      u_int32_t number;
      int set_persist;
{
      LOGP persist;
      ssize_t nw;
      char *fname;
      int fd, ret;

      /* Try to open the log file. */
      if ((ret = __log_name(dblp,
          number, &fname, &fd, DB_RDONLY | DB_SEQUENTIAL)) != 0) {
            __os_freestr(fname);
            return (ret);
      }

      /* Try to read the header. */
      if ((ret = __os_seek(fd, 0, 0, sizeof(HDR), 0, SEEK_SET)) != 0 ||
          (ret = __os_read(fd, &persist, sizeof(LOGP), &nw)) != 0 ||
          nw != sizeof(LOGP)) {
            if (ret == 0)
                  ret = EIO;

            (void)__os_close(fd);

            __db_err(dblp->dbenv,
                "Ignoring log file: %s: %s", fname, strerror(ret));
            goto err;
      }
      (void)__os_close(fd);

      /* Validate the header. */
      if (persist.magic != DB_LOGMAGIC) {
            __db_err(dblp->dbenv,
                "Ignoring log file: %s: magic number %lx, not %lx",
                fname, (u_long)persist.magic, (u_long)DB_LOGMAGIC);
            ret = EINVAL;
            goto err;
      }
      if (persist.version < DB_LOGOLDVER || persist.version > DB_LOGVERSION) {
            __db_err(dblp->dbenv,
                "Ignoring log file: %s: unsupported log version %lu",
                fname, (u_long)persist.version);
            ret = EINVAL;
            goto err;
      }

      /*
       * If we're going to use this log file, set the region's persistent
       * information based on the headers.
       */
      if (set_persist) {
            dblp->lp->persist.lg_max = persist.lg_max;
            dblp->lp->persist.mode = persist.mode;
      }
      ret = 0;

err:  __os_freestr(fname);
      return (ret);
}

/*
 * log_close --
 *    Close a log.
 */
int
log_close(dblp)
      DB_LOG *dblp;
{
      u_int32_t i;
      int ret, t_ret;

      LOG_PANIC_CHECK(dblp);

      /* We may have opened files as part of XA; if so, close them. */
      __log_close_files(dblp);

      /* Discard the per-thread pointer. */
      if (dblp->mutexp != NULL) {
            LOCK_LOGREGION(dblp);
            __db_shalloc_free(dblp->addr, dblp->mutexp);
            UNLOCK_LOGREGION(dblp);
      }

      /* Close the region. */
      ret = __db_rdetach(&dblp->reginfo);

      /* Close open files, release allocated memory. */
      if (dblp->lfd != -1 && (t_ret = __os_close(dblp->lfd)) != 0 && ret == 0)
            ret = t_ret;
      if (dblp->c_dbt.data != NULL)
            __os_free(dblp->c_dbt.data, dblp->c_dbt.ulen);
      if (dblp->c_fd != -1 &&
          (t_ret = __os_close(dblp->c_fd)) != 0 && ret == 0)
            ret = t_ret;
      if (dblp->dbentry != NULL) {
            for (i = 0; i < dblp->dbentry_cnt; i++)
                  if (dblp->dbentry[i].name != NULL)
                        __os_freestr(dblp->dbentry[i].name);
            __os_free(dblp->dbentry,
                (dblp->dbentry_cnt * sizeof(DB_ENTRY)));
      }

      if (dblp->dir != NULL)
            __os_freestr(dblp->dir);

      if (dblp->reginfo.path != NULL)
            __os_freestr(dblp->reginfo.path);
      __os_free(dblp, sizeof(*dblp));

      return (ret);
}

/*
 * log_unlink --
 *    Exit a log.
 */
int
log_unlink(path, force, dbenv)
      const char *path;
      int force;
      DB_ENV *dbenv;
{
      REGINFO reginfo;
      int ret;

      memset(&reginfo, 0, sizeof(reginfo));
      reginfo.dbenv = dbenv;
      reginfo.appname = DB_APP_LOG;
      if (path != NULL && (ret = __os_strdup(path, &reginfo.path)) != 0)
            return (ret);
      reginfo.file = DB_DEFAULT_LOG_FILE;
      ret = __db_runlink(&reginfo, force);
      if (reginfo.path != NULL)
            __os_freestr(reginfo.path);
      return (ret);
}

/*
 * log_stat --
 *    Return LOG statistics.
 */
int
log_stat(dblp, gspp, db_malloc)
      DB_LOG *dblp;
      DB_LOG_STAT **gspp;
      void *(*db_malloc) __P((size_t));
{
      LOG *lp;
      int ret;

      *gspp = NULL;
      lp = dblp->lp;

      LOG_PANIC_CHECK(dblp);

      if ((ret = __os_malloc(sizeof(**gspp), db_malloc, gspp)) != 0)
            return (ret);

      /* Copy out the global statistics. */
      LOCK_LOGREGION(dblp);
      **gspp = lp->stat;

      (*gspp)->st_magic = lp->persist.magic;
      (*gspp)->st_version = lp->persist.version;
      (*gspp)->st_mode = lp->persist.mode;
      (*gspp)->st_lg_max = lp->persist.lg_max;

      (*gspp)->st_region_nowait = lp->rlayout.lock.mutex_set_nowait;
      (*gspp)->st_region_wait = lp->rlayout.lock.mutex_set_wait;

      (*gspp)->st_cur_file = lp->lsn.file;
      (*gspp)->st_cur_offset = lp->lsn.offset;

      (*gspp)->st_refcnt = lp->rlayout.refcnt;
      (*gspp)->st_regsize = lp->rlayout.size;

      UNLOCK_LOGREGION(dblp);

      return (0);
}

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