/*-
 * 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     10.44 (Sleepycat) 11/3/98";
#endif /* not lint */

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

#include <errno.h>
#include <stdio.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 "clib_ext.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;

        LOG_PANIC_CHECK(dblp);

        /* Validate arguments. */
        if (flags != 0 && flags != DB_CHECKPOINT &&
            flags != DB_CURLSN && flags != DB_FLUSH)
                return (__db_ferr(dblp->dbenv, "log_put", 0));

        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 (flags == 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)) {
                        if (fnp->ref == 0)      /* Entry not in use. */
                                continue;
                        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;

        LOG_PANIC_CHECK(dblp);

        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 && log_compare(lsn, &lp->f_lsn) >= 0) {
                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 = __os_fsync(dblp->lfd)) != 0) {
                __db_panic(dblp->dbenv, ret);
                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.
         *
         * XXX
         * Check to make sure that the saved lsn isn't 0 before we go making
         * this change.  If DB_CHECKPOINT was called before we actually wrote
         * something, you can end up here without ever having written anything
         * to a log file, and decrementing either s_lsn.file or s_lsn.offset
         * will cause much sadness later on.
         */
        lp->s_lsn = lp->f_lsn;
        if (!current && lp->s_lsn.file != 0)
                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 = __os_seek(dblp->lfd, 0, 0, lp->w_off, 0, SEEK_SET)) != 0 ||
            (ret = __os_write(dblp->lfd, addr, len, &nw)) != 0) {
                __db_panic(dblp->dbenv, ret);
                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 *name;

        LOG_PANIC_CHECK(dblp);

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

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

        return (0);
}

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

        /* Close any previous file descriptor. */
        if (dblp->lfd != -1) {
                (void)__os_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, &name, &dblp->lfd, DB_CREATE | DB_SEQUENTIAL)) != 0)
                __db_err(dblp->dbenv, "log_put: %s: %s", name, strerror(ret));

        __os_freestr(name);
        return (ret);
}

/*
 * __log_name --
 *      Return the log name for a particular file, and optionally open it.
 *
 * PUBLIC: int __log_name __P((DB_LOG *, u_int32_t, char **, int *, u_int32_t));
 */
int
__log_name(dblp, filenumber, namep, fdp, flags)
        DB_LOG *dblp;
        u_int32_t filenumber, flags;
        char **namep;
        int *fdp;
{
        int ret;
        char *oname;
        char old[sizeof(LFPREFIX) + 5 + 20], new[sizeof(LFPREFIX) + 10 + 20];

        /*
         * !!!
         * The semantics of this routine are bizarre.
         *
         * The reason for all of this is that we need a place where we can
         * intercept requests for log files, and, if appropriate, check for
         * both the old-style and new-style log file names.  The trick is
         * that all callers of this routine that are opening the log file
         * read-only want to use an old-style file name if they can't find
         * a match using a new-style name.  The only down-side is that some
         * callers may check for the old-style when they really don't need
         * to, but that shouldn't mess up anything, and we only check for
         * the old-style name when we've already failed to find a new-style
         * one.
         *
         * Create a new-style file name, and if we're not going to open the
         * file, return regardless.
         */
        (void)snprintf(new, sizeof(new), LFNAME, filenumber);
        if ((ret = __db_appname(dblp->dbenv,
            DB_APP_LOG, dblp->dir, new, 0, NULL, namep)) != 0 || fdp == NULL)
                return (ret);

        /* Open the new-style file -- if we succeed, we're done. */
        if ((ret = __db_open(*namep,
            flags, flags, dblp->lp->persist.mode, fdp)) == 0)
                return (0);

        /*
         * The open failed... if the DB_RDONLY flag isn't set, we're done,
         * the caller isn't interested in old-style files.
         */
        if (!LF_ISSET(DB_RDONLY))
                return (ret);

        /* Create an old-style file name. */
        (void)snprintf(old, sizeof(old), LFNAME_V1, filenumber);
        if ((ret = __db_appname(dblp->dbenv,
            DB_APP_LOG, dblp->dir, old, 0, NULL, &oname)) != 0)
                goto err;

        /*
         * Open the old-style file -- if we succeed, we're done.  Free the
         * space allocated for the new-style name and return the old-style
         * name to the caller.
         */
        if ((ret = __db_open(oname,
            flags, flags, dblp->lp->persist.mode, fdp)) == 0) {
                __os_freestr(*namep);
                *namep = oname;
                return (0);
        }

        /*
         * Couldn't find either style of name -- return the new-style name
         * for the caller's error message.  If it's an old-style name that's
         * actually missing we're going to confuse the user with the error
         * message, but that implies that not only were we looking for an
         * old-style name, but we expected it to exist and we weren't just
         * looking for any log file.  That's not a likely error.
         */
err:    __os_freestr(oname);
        return (ret);
}