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log_put.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_put.c     10.35 (Sleepycat) 5/6/98";
#endif /* not lint */

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

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

#include "db_int.h"
#include "shqueue.h"
#include "db_page.h"
#include "log.h"
#include "hash.h"
#include "common_ext.h"

static int __log_fill __P((DB_LOG *, DB_LSN *, void *, u_int32_t));
static int __log_flush __P((DB_LOG *, const DB_LSN *));
static int __log_newfd __P((DB_LOG *));
static int __log_putr __P((DB_LOG *, DB_LSN *, const DBT *, u_int32_t));
static int __log_write __P((DB_LOG *, void *, u_int32_t));

/*
 * log_put --
 *    Write a log record.
 */
int
log_put(dblp, lsn, dbt, flags)
      DB_LOG *dblp;
      DB_LSN *lsn;
      const DBT *dbt;
      u_int32_t flags;
{
      int ret;

      /* Validate arguments. */
#define     OKFLAGS     (DB_CHECKPOINT | DB_FLUSH | DB_CURLSN)
      if (flags != 0) {
            if ((ret =
                __db_fchk(dblp->dbenv, "log_put", flags, OKFLAGS)) != 0)
                  return (ret);
            switch (flags) {
            case DB_CHECKPOINT:
            case DB_CURLSN:
            case DB_FLUSH:
            case 0:
                  break;
            default:
                  return (__db_ferr(dblp->dbenv, "log_put", 1));
            }
      }

      LOCK_LOGREGION(dblp);
      ret = __log_put(dblp, lsn, dbt, flags);
      UNLOCK_LOGREGION(dblp);
      return (ret);
}

/*
 * __log_put --
 *    Write a log record; internal version.
 *
 * PUBLIC: int __log_put __P((DB_LOG *, DB_LSN *, const DBT *, u_int32_t));
 */
int
__log_put(dblp, lsn, dbt, flags)
      DB_LOG *dblp;
      DB_LSN *lsn;
      const DBT *dbt;
      u_int32_t flags;
{
      DBT fid_dbt, t;
      DB_LSN r_unused;
      FNAME *fnp;
      LOG *lp;
      u_int32_t lastoff;
      int ret;

      lp = dblp->lp;

      /*
       * If the application just wants to know where we are, fill in
       * the information.  Currently used by the transaction manager
       * to avoid writing TXN_begin records.
       */
      if (LF_ISSET(DB_CURLSN)) {
            lsn->file = lp->lsn.file;
            lsn->offset = lp->lsn.offset;
            return (0);
      }

      /* If this information won't fit in the file, swap files. */
      if (lp->lsn.offset + sizeof(HDR) + dbt->size > lp->persist.lg_max) {
            if (sizeof(HDR) +
                sizeof(LOGP) + dbt->size > lp->persist.lg_max) {
                  __db_err(dblp->dbenv,
                      "log_put: record larger than maximum file size");
                  return (EINVAL);
            }

            /* Flush the log. */
            if ((ret = __log_flush(dblp, NULL)) != 0)
                  return (ret);

            /*
             * Save the last known offset from the previous file, we'll
             * need it to initialize the persistent header information.
             */
            lastoff = lp->lsn.offset;

            /* Point the current LSN to the new file. */
            ++lp->lsn.file;
            lp->lsn.offset = 0;

            /* Reset the file write offset. */
            lp->w_off = 0;
      } else
            lastoff = 0;

      /* Initialize the LSN information returned to the user. */
      lsn->file = lp->lsn.file;
      lsn->offset = lp->lsn.offset;

      /*
       * Insert persistent information as the first record in every file.
       * Note that the previous length is wrong for the very first record
       * of the log, but that's okay, we check for it during retrieval.
       */
      if (lp->lsn.offset == 0) {
            t.data = &lp->persist;
            t.size = sizeof(LOGP);
            if ((ret = __log_putr(dblp, lsn,
                &t, lastoff == 0 ? 0 : lastoff - lp->len)) != 0)
                  return (ret);

            /* Update the LSN information returned to the user. */
            lsn->file = lp->lsn.file;
            lsn->offset = lp->lsn.offset;
      }

      /* Write the application's log record. */
      if ((ret = __log_putr(dblp, lsn, dbt, lp->lsn.offset - lp->len)) != 0)
            return (ret);

      /*
       * On a checkpoint, we:
       *    Put out the checkpoint record (above).
       *    Save the LSN of the checkpoint in the shared region.
       *    Append the set of file name information into the log.
       */
      if (flags == DB_CHECKPOINT) {
            lp->chkpt_lsn = *lsn;

            for (fnp = SH_TAILQ_FIRST(&dblp->lp->fq, __fname);
                fnp != NULL; fnp = SH_TAILQ_NEXT(fnp, q, __fname)) {
                  memset(&t, 0, sizeof(t));
                  t.data = R_ADDR(dblp, fnp->name_off);
                  t.size = strlen(t.data) + 1;
                  memset(&fid_dbt, 0, sizeof(fid_dbt));
                  fid_dbt.data = fnp->ufid;
                  fid_dbt.size = DB_FILE_ID_LEN;
                  if ((ret = __log_register_log(dblp, NULL, &r_unused, 0,
                      LOG_CHECKPOINT, &t, &fid_dbt, fnp->id, fnp->s_type))
                      != 0)
                        return (ret);
            }
      }

      /*
       * On a checkpoint or when flush is requested, we:
       *    Flush the current buffer contents to disk.
       *    Sync the log to disk.
       */
      if (flags == DB_FLUSH || flags == DB_CHECKPOINT)
            if ((ret = __log_flush(dblp, NULL)) != 0)
                  return (ret);

      /*
       * On a checkpoint, we:
       *    Save the time the checkpoint was written.
       *    Reset the bytes written since the last checkpoint.
       */
      if (flags == DB_CHECKPOINT) {
            (void)time(&lp->chkpt);
            lp->stat.st_wc_bytes = lp->stat.st_wc_mbytes = 0;
      }
      return (0);
}

/*
 * __log_putr --
 *    Actually put a record into the log.
 */
static int
__log_putr(dblp, lsn, dbt, prev)
      DB_LOG *dblp;
      DB_LSN *lsn;
      const DBT *dbt;
      u_int32_t prev;
{
      HDR hdr;
      LOG *lp;
      int ret;

      lp = dblp->lp;

      /*
       * Initialize the header.  If we just switched files, lsn.offset will
       * be 0, and what we really want is the offset of the previous record
       * in the previous file.  Fortunately, prev holds the value we want.
       */
      hdr.prev = prev;
      hdr.len = sizeof(HDR) + dbt->size;
      hdr.cksum = __ham_func4(dbt->data, dbt->size);

      if ((ret = __log_fill(dblp, lsn, &hdr, sizeof(HDR))) != 0)
            return (ret);
      lp->len = sizeof(HDR);
      lp->lsn.offset += sizeof(HDR);

      if ((ret = __log_fill(dblp, lsn, dbt->data, dbt->size)) != 0)
            return (ret);
      lp->len += dbt->size;
      lp->lsn.offset += dbt->size;
      return (0);
}

/*
 * log_flush --
 *    Write all records less than or equal to the specified LSN.
 */
int
log_flush(dblp, lsn)
      DB_LOG *dblp;
      const DB_LSN *lsn;
{
      int ret;

      LOCK_LOGREGION(dblp);
      ret = __log_flush(dblp, lsn);
      UNLOCK_LOGREGION(dblp);
      return (ret);
}

/*
 * __log_flush --
 *    Write all records less than or equal to the specified LSN; internal
 *    version.
 */
static int
__log_flush(dblp, lsn)
      DB_LOG *dblp;
      const DB_LSN *lsn;
{
      DB_LSN t_lsn;
      LOG *lp;
      int current, ret;

      ret = 0;
      lp = dblp->lp;

      /*
       * If no LSN specified, flush the entire log by setting the flush LSN
       * to the last LSN written in the log.  Otherwise, check that the LSN
       * isn't a non-existent record for the log.
       */
      if (lsn == NULL) {
            t_lsn.file = lp->lsn.file;
            t_lsn.offset = lp->lsn.offset - lp->len;
            lsn = &t_lsn;
      } else
            if (lsn->file > lp->lsn.file ||
                (lsn->file == lp->lsn.file &&
                lsn->offset > lp->lsn.offset - lp->len)) {
                  __db_err(dblp->dbenv,
                      "log_flush: LSN past current end-of-log");
                  return (EINVAL);
            }

      /*
       * If the LSN is less than the last-sync'd LSN, we're done.  Note,
       * the last-sync LSN saved in s_lsn is the LSN of the first byte
       * we absolutely know has been written to disk, so the test is <=.
       */
      if (lsn->file < lp->s_lsn.file ||
          (lsn->file == lp->s_lsn.file && lsn->offset <= lp->s_lsn.offset))
            return (0);

      /*
       * We may need to write the current buffer.  We have to write the
       * current buffer if the flush LSN is greater than or equal to the
       * buffer's starting LSN.
       */
      current = 0;
      if (lp->b_off != 0 &&
          lsn->file >= lp->f_lsn.file && lsn->offset >= lp->f_lsn.offset) {
            if ((ret = __log_write(dblp, lp->buf, lp->b_off)) != 0)
                  return (ret);

            lp->b_off = 0;
            current = 1;
      }

      /*
       * It's possible that this thread may never have written to this log
       * file.  Acquire a file descriptor if we don't already have one.
       */
      if (dblp->lfname != dblp->lp->lsn.file)
            if ((ret = __log_newfd(dblp)) != 0)
                  return (ret);

      /* Sync all writes to disk. */
      if ((ret = __db_fsync(dblp->lfd)) != 0)
            return (ret);
      ++lp->stat.st_scount;

      /*
       * Set the last-synced LSN, using the LSN of the current buffer.  If
       * the current buffer was flushed, we know the LSN of the first byte
       * of the buffer is on disk, otherwise, we only know that the LSN of
       * the record before the one beginning the current buffer is on disk.
       */
      lp->s_lsn = lp->f_lsn;
      if (!current) {
            if (lp->s_lsn.offset == 0) {
                  --lp->s_lsn.file;
                  lp->s_lsn.offset = lp->persist.lg_max;
            } else
                  --lp->s_lsn.offset;
      }

      return (0);
}

/*
 * __log_fill --
 *    Write information into the log.
 */
static int
__log_fill(dblp, lsn, addr, len)
      DB_LOG *dblp;
      DB_LSN *lsn;
      void *addr;
      u_int32_t len;
{
      LOG *lp;
      u_int32_t nrec;
      size_t nw, remain;
      int ret;

      /* Copy out the data. */
      for (lp = dblp->lp; len > 0;) {
            /*
             * If we're beginning a new buffer, note the user LSN to which
             * the first byte of the buffer belongs.  We have to know this
             * when flushing the buffer so that we know if the in-memory
             * buffer needs to be flushed.
             */
            if (lp->b_off == 0)
                  lp->f_lsn = *lsn;

            /*
             * If we're on a buffer boundary and the data is big enough,
             * copy as many records as we can directly from the data.
             */
            if (lp->b_off == 0 && len >= sizeof(lp->buf)) {
                  nrec = len / sizeof(lp->buf);
                  if ((ret = __log_write(dblp,
                      addr, nrec * sizeof(lp->buf))) != 0)
                        return (ret);
                  addr = (u_int8_t *)addr + nrec * sizeof(lp->buf);
                  len -= nrec * sizeof(lp->buf);
                  continue;
            }

            /* Figure out how many bytes we can copy this time. */
            remain = sizeof(lp->buf) - lp->b_off;
            nw = remain > len ? len : remain;
            memcpy(lp->buf + lp->b_off, addr, nw);
            addr = (u_int8_t *)addr + nw;
            len -= nw;
            lp->b_off += nw;

            /* If we fill the buffer, flush it. */
            if (lp->b_off == sizeof(lp->buf)) {
                  if ((ret =
                      __log_write(dblp, lp->buf, sizeof(lp->buf))) != 0)
                        return (ret);
                  lp->b_off = 0;
            }
      }
      return (0);
}

/*
 * __log_write --
 *    Write the log buffer to disk.
 */
static int
__log_write(dblp, addr, len)
      DB_LOG *dblp;
      void *addr;
      u_int32_t len;
{
      LOG *lp;
      ssize_t nw;
      int ret;

      /*
       * If we haven't opened the log file yet or the current one
       * has changed, acquire a new log file.
       */
      lp = dblp->lp;
      if (dblp->lfd == -1 || dblp->lfname != lp->lsn.file)
            if ((ret = __log_newfd(dblp)) != 0)
                  return (ret);

      /*
       * Seek to the offset in the file (someone may have written it
       * since we last did).
       */
      if ((ret = __db_seek(dblp->lfd, 0, 0, lp->w_off, 0, SEEK_SET)) != 0)
            return (ret);
      if ((ret = __db_write(dblp->lfd, addr, len, &nw)) != 0)
            return (ret);
      if (nw != (int32_t)len)
            return (EIO);

      /* Reset the buffer offset and update the seek offset. */
      lp->w_off += len;

      /* Update written statistics. */
      if ((lp->stat.st_w_bytes += len) >= MEGABYTE) {
            lp->stat.st_w_bytes -= MEGABYTE;
            ++lp->stat.st_w_mbytes;
      }
      if ((lp->stat.st_wc_bytes += len) >= MEGABYTE) {
            lp->stat.st_wc_bytes -= MEGABYTE;
            ++lp->stat.st_wc_mbytes;
      }
      ++lp->stat.st_wcount;

      return (0);
}

/*
 * log_file --
 *    Map a DB_LSN to a file name.
 */
int
log_file(dblp, lsn, namep, len)
      DB_LOG *dblp;
      const DB_LSN *lsn;
      char *namep;
      size_t len;
{
      int ret;
      char *p;

      LOCK_LOGREGION(dblp);
      ret = __log_name(dblp, lsn->file, &p);
      UNLOCK_LOGREGION(dblp);
      if (ret != 0)
            return (ret);

      /* Check to make sure there's enough room and copy the name. */
      if (len < strlen(p) + 1) {
            *namep = '\0';
            return (ENOMEM);
      }
      (void)strcpy(namep, p);
      __db_free(p);

      return (0);
}

/*
 * __log_newfd --
 *    Acquire a file descriptor for the current log file.
 */
static int
__log_newfd(dblp)
      DB_LOG *dblp;
{
      int ret;
      char *p;

      /* Close any previous file descriptor. */
      if (dblp->lfd != -1) {
            (void)__db_close(dblp->lfd);
            dblp->lfd = -1;
      }

      /* Get the path of the new file and open it. */
      dblp->lfname = dblp->lp->lsn.file;
      if ((ret = __log_name(dblp, dblp->lfname, &p)) != 0)
            return (ret);
      if ((ret = __db_open(p,
          DB_CREATE | DB_SEQUENTIAL,
          DB_CREATE | DB_SEQUENTIAL,
          dblp->lp->persist.mode, &dblp->lfd)) != 0)
            __db_err(dblp->dbenv,
                "log_put: %s: %s", p, strerror(ret));
      FREES(p);
      return (ret);
}

/*
 * __log_name --
 *    Return the log name for a particular file.
 *
 * PUBLIC: int __log_name __P((DB_LOG *, int, char **));
 */
int
__log_name(dblp, filenumber, namep)
      DB_LOG *dblp;
      char **namep;
      int filenumber;
{
      char name[sizeof(LFNAME) + 10];

      (void)snprintf(name, sizeof(name), LFNAME, filenumber);
      return (__db_appname(dblp->dbenv,
          DB_APP_LOG, dblp->dir, name, 0, NULL, namep));
}

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