db/xa/xa.c

	xa.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1998
 *  Sleepycat Software.  All rights reserved.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/* XXX Remove the global transaction and hang it off the environment. */
#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)xa.c  10.4 (Sleepycat) 10/11/98";
#endif /* not lint */

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

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#endif

#include "db_int.h"
#include "db_page.h"
#include "shqueue.h"
#include "log.h"
#include "txn.h"
#include "db_auto.h"
#include "db_ext.h"
#include "db_dispatch.h"

static int  __db_xa_close __P((char *, int, long));
static int  __db_xa_commit __P((XID *, int, long));
static int  __db_xa_complete __P((int *, int *, int, long));
static int  __db_xa_end __P((XID *, int, long));
static int  __db_xa_forget __P((XID *, int, long));
static int  __db_xa_open __P((char *, int, long));
static int  __db_xa_prepare __P((XID *, int, long));
static int  __db_xa_recover __P((XID *, long, int, long));
static int  __db_xa_rollback __P((XID *, int, long));
static int  __db_xa_start __P((XID *, int, long));
static void __xa_txn_end __P((DB_ENV *));
static void __xa_txn_init __P((DB_ENV *, TXN_DETAIL *, size_t));

/*
 * Possible flag values:
 *  Dynamic registration    0 => no dynamic registration
 *              TMREGISTER => dynamic registration
 *  Asynchronous operation  0 => no support for asynchrony
 *              TMUSEASYNC => async support
 *  Migration support   0 => migration of transactions across
 *                   threads is possible
 *              TMNOMIGRATE => no migration across threads
 */
const struct xa_switch_t db_xa_switch = {
     "Berkeley DB",     /* name[RMNAMESZ] */
     TMNOMIGRATE,       /* flags */
     0,         /* version */
     __db_xa_open,      /* xa_open_entry */
     __db_xa_close,     /* xa_close_entry */
     __db_xa_start,     /* xa_start_entry */
     __db_xa_end,       /* xa_end_entry */
     __db_xa_rollback,  /* xa_rollback_entry */
     __db_xa_prepare,   /* xa_prepare_entry */
     __db_xa_commit,    /* xa_commit_entry */
     __db_xa_recover,   /* xa_recover_entry */
     __db_xa_forget,    /* xa_forget_entry */
     __db_xa_complete   /* xa_complete_entry */
};

/*
 * __db_xa_open --
 *  The open call in the XA protocol.  The rmid field is an id number
 * that the TM assigned us and will pass us on every xa call.  We need to
 * map that rmid number into a dbenv structure that we create during
 * initialization.  Since this id number is thread specific, we do not
 * need to store it in shared memory.  The file xa_map.c implements all
 * such xa->db mappings.
 *  The xa_info field is instance specific information.  We require
 * that the value of DB_HOME be passed in xa_info.  Since xa_info is the
 * only thing that we get to pass to db_appinit, any config information
 * will have to be done via a config file instead of via the db_appinit
 * call.
 */
static int
__db_xa_open(xa_info, rmid, flags)
    char *xa_info;
    int rmid;
    long flags;
{
    DB_ENV *env;

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);
    if (flags != TMNOFLAGS)
        return (XAER_INVAL);

    /* Verify if we already have this environment open. */
    if (__db_rmid_to_env(rmid, &env, 0) == 0)
        return (XA_OK);

    /*
     * Since we cannot tell whether the environment is OK or not,
     * we can't actually do the db_appinit in xa_open.  Instead,
     * we save the mapping between the rmid and the xa_info.  If
     * we next get a call to __xa_recover, we do the db_appinit
     * with DB_RECOVER set.  If we get any other call, then we
     * do the db_appinit.
     */
    return (__db_map_rmid_name(rmid, xa_info));
}

/*
 * __db_xa_close --
 *  The close call of the XA protocol.  The only trickiness here
 * is that if there are any active transactions, we must fail.  It is
 * *not* an error to call close on an environment that has already been
 * closed (I am interpreting that to mean it's OK to call close on an
 * environment that has never been opened).
 */
static int
__db_xa_close(xa_info, rmid, flags)
    char *xa_info;
    int rmid;
    long flags;
{
    DB_ENV *env;
    int ret, t_ret;

    COMPQUIET(xa_info, NULL);

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);
    if (flags != TMNOFLAGS)
        return (XAER_INVAL);

    /* If the environment is closed, then we're done. */
    if (__db_rmid_to_env(rmid, &env, 0) != 0)
        return (XA_OK);

    /* Check if there are any pending transactions. */
    if (env->xa_txn != NULL && env->xa_txn->txnid != TXN_INVALID)
        return (XAER_PROTO);

    /* Now, destroy the mapping and close the environment. */
    ret = __db_unmap_rmid(rmid);
    if ((t_ret = db_appexit(env)) != 0 && ret == 0)
        ret = t_ret;

    __os_free(env, sizeof(DB_ENV));

    return (ret == 0 ? XA_OK : XAER_RMERR);
}

/*
 * __db_xa_start --
 *  Begin a transaction for the current resource manager.
 */
static int
__db_xa_start(xid, rmid, flags)
    XID *xid;
    int rmid;
    long flags;
{
    DB_ENV *env;
    TXN_DETAIL *td;
    size_t off;
    int is_known;

#define OK_FLAGS    (TMJOIN | TMRESUME | TMNOWAIT | TMASYNC | TMNOFLAGS)
    if (LF_ISSET(~OK_FLAGS))
        return (XAER_INVAL);

    if (LF_ISSET(TMJOIN) && LF_ISSET(TMRESUME))
        return (XAER_INVAL);

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);

    if (__db_rmid_to_env(rmid, &env, 1) != 0)
        return (XAER_PROTO);

    is_known = __db_xid_to_txn(env, xid, &off) == 0;

    if (is_known && !LF_ISSET(TMRESUME) && !LF_ISSET(TMJOIN))
        return (XAER_DUPID);

    if (!is_known && LF_ISSET(TMRESUME | TMJOIN))
        return (XAER_NOTA);

    /*
     * This can't block, so we can ignore TMNOWAIT.
     *
     * Other error conditions: RMERR, RMFAIL, OUTSIDE, PROTO, RB*
     */
    if (is_known) {
        td = (TXN_DETAIL *)((u_int8_t *)env->tx_info->region + off);
        if (td->xa_status == TXN_XA_SUSPENDED && !LF_ISSET(TMRESUME))
            return (XAER_PROTO);
        if (td->xa_status == TXN_XA_DEADLOCKED)
            return (XA_RBDEADLOCK);
        if (td->xa_status == TXN_XA_ABORTED)
            return (XA_RBOTHER);

        /* Now, fill in the global transaction structure. */
        __xa_txn_init(env, td, off);
        td->xa_status = TXN_XA_STARTED;
    } else {
        if (__txn_xa_begin(env, env->xa_txn) != 0)
            return (XAER_RMERR);
        (void)__db_map_xid(env, xid, env->xa_txn->off);
        td = (TXN_DETAIL *)
            ((u_int8_t *)env->tx_info->region + env->xa_txn->off);
        td->xa_status = TXN_XA_STARTED;
    }
    return (XA_OK);
}

/*
 * __db_xa_end --
 *  Disassociate the current transaction from the current process.
 */
static int
__db_xa_end(xid, rmid, flags)
    XID *xid;
    int rmid;
    long flags;
{
    DB_ENV *env;
    DB_TXN *txn;
    TXN_DETAIL *td;
    size_t off;

    if (flags != TMNOFLAGS && !LF_ISSET(TMSUSPEND | TMSUCCESS | TMFAIL))
        return (XAER_INVAL);

    if (__db_rmid_to_env(rmid, &env, 0) != 0)
        return (XAER_PROTO);

    if (__db_xid_to_txn(env, xid, &off) != 0)
        return (XAER_NOTA);

    txn = env->xa_txn;
    if (off != txn->off)
        return (XAER_PROTO);

    td = (TXN_DETAIL *)((u_int8_t *)env->tx_info->region + off);
    if (td->xa_status == TXN_XA_DEADLOCKED)
        return (XA_RBDEADLOCK);

    if (td->status == TXN_ABORTED)
        return (XA_RBOTHER);

    if (td->xa_status != TXN_XA_STARTED)
        return (XAER_PROTO);

    /* Update the shared memory last_lsn field */
    td->last_lsn = txn->last_lsn;

    /*
     * If we ever support XA migration, we cannot keep SUSPEND/END
     * status in the shared region; it would have to be process local.
     */
    if (LF_ISSET(TMSUSPEND))
        td->xa_status = TXN_XA_SUSPENDED;
    else
        td->xa_status = TXN_XA_ENDED;

    txn->txnid = TXN_INVALID;
    return (XA_OK);
}

/*
 * __db_xa_prepare --
 *  Sync the log to disk so we can guarantee recoverability.
 */
static int
__db_xa_prepare(xid, rmid, flags)
    XID *xid;
    int rmid;
    long flags;
{
    DB_ENV *env;
    TXN_DETAIL *td;
    size_t off;

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);
    if (flags != TMNOFLAGS)
        return (XAER_INVAL);

    /*
     * We need to know if we've ever called prepare on this.
     * As part of the prepare, we set the xa_status field to
     * reflect that fact that prepare has been called, and if
     * it's ever called again, it's an error.
     */
    if (__db_rmid_to_env(rmid, &env, 1) != 0)
        return (XAER_PROTO);

    if (__db_xid_to_txn(env, xid, &off) != 0)
        return (XAER_NOTA);

    td = (TXN_DETAIL *)((u_int8_t *)env->tx_info->region + off);

    if (td->xa_status == TXN_XA_DEADLOCKED)
        return (XA_RBDEADLOCK);

    if (td->xa_status != TXN_XA_ENDED && td->xa_status != TXN_XA_SUSPENDED)
        return (XAER_PROTO);

    /* Now, fill in the global transaction structure. */
    __xa_txn_init(env, td, off);

    if (txn_prepare(env->xa_txn) != 0)
        return (XAER_RMERR);

    td->xa_status = TXN_XA_PREPARED;

    /* No fatal value that would require an XAER_RMFAIL. */
    __xa_txn_end(env);
    return (XA_OK);
}

/*
 * __db_xa_commit --
 *  Commit the transaction
 */
static int
__db_xa_commit(xid, rmid, flags)
    XID *xid;
    int rmid;
    long flags;
{
    DB_ENV *env;
    TXN_DETAIL *td;
    size_t off;

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);
#undef  OK_FLAGS
#define OK_FLAGS    (TMNOFLAGS | TMNOWAIT | TMONEPHASE)
    if (LF_ISSET(~OK_FLAGS))
        return (XAER_INVAL);

    /*
     * We need to know if we've ever called prepare on this.
     * We can verify this by examining the xa_status field.
     */
    if (__db_rmid_to_env(rmid, &env, 1) != 0)
        return (XAER_PROTO);

    if (__db_xid_to_txn(env, xid, &off) != 0)
        return (XAER_NOTA);

    td = (TXN_DETAIL *)((u_int8_t *)env->tx_info->region + off);

    if (td->xa_status == TXN_XA_DEADLOCKED)
        return (XA_RBDEADLOCK);

    if (td->xa_status == TXN_XA_ABORTED)
        return (XA_RBOTHER);

    if (LF_ISSET(TMONEPHASE) &&
        td->xa_status != TXN_XA_ENDED && td->xa_status != TXN_XA_SUSPENDED)
        return (XAER_PROTO);

    if (!LF_ISSET(TMONEPHASE) && td->xa_status != TXN_XA_PREPARED)
        return (XAER_PROTO);

    /* Now, fill in the global transaction structure. */
    __xa_txn_init(env, td, off);

    if (txn_commit(env->xa_txn) != 0)
        return (XAER_RMERR);

    /* No fatal value that would require an XAER_RMFAIL. */
    __xa_txn_end(env);
    return (XA_OK);
}

/*
 * __db_xa_recover --
 *  Returns a list of prepared and heuristically completed transactions.
 *
 * The return value is the number of xids placed into the xid array (less
 * than or equal to the count parameter).  The flags are going to indicate
 * whether we are starting a scan or continuing one.
 */
static int
__db_xa_recover(xids, count, rmid, flags)
    XID *xids;
    long count, flags;
    int rmid;
{
    __txn_xa_regop_args *argp;
    DBT data;
    DB_ENV *env;
    DB_LOG *log;
    XID *xidp;
    char *dbhome;
    int err, ret;
    u_int32_t rectype, txnid;

    ret = 0;
    xidp = xids;


    /*
     * If we are starting a scan, then we need to open the environment
     * and run recovery.  This recovery puts us in a state where we can
     * either commit or abort any transactions that were prepared but not
     * yet committed.  Once we've done that, we need to figure out where
     * to begin checking for such transactions.  If we are not starting
     * a scan, then the environment had better have already been recovered
     * and we'll start from * wherever the log cursor is.  Since XA apps
     * cannot be threaded, we don't have to worry about someone else
     * having moved it.
     */
    if (LF_ISSET(TMSTARTRSCAN)) {
        /* If the environment is open, we have a problem. */
        if (__db_rmid_to_env(rmid, &env, 0) == XA_OK)
            return (XAER_PROTO);

        if ((ret = __os_calloc(1, sizeof(DB_ENV), &env)) != 0)
            return (XAER_RMERR);

        if (__db_rmid_to_name(rmid, &dbhome) != 0)
            goto err1;

#undef XA_FLAGS
#define XA_FLAGS DB_RECOVER | \
    DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN
        if ((ret = db_appinit(dbhome, NULL, env, XA_FLAGS)) != 0)
            goto err1;

        if (__db_map_rmid(rmid, env) != 0)
            goto err2;

        /* Now figure out from where to begin scan. */
        log = env->lg_info;
        if ((err = __log_findckp(log, &log->xa_first)) == DB_NOTFOUND) {
            /*
             * If there were no log files, then we have no
             * transactions to return, so we simply return 0.
             */
            return (0);
        }
        if ((err = __db_txnlist_init(&log->xa_info)) != 0)
            goto err3;
    } else {
        /* We had better already know about this rmid. */
        if (__db_rmid_to_env(rmid, &env, 0) != 0)
            return (XAER_PROTO);
        /*
         * If we are not starting a scan, the log cursor had
         * better be set.
         */
        log = env->lg_info;
        if (IS_ZERO_LSN(log->xa_lsn))
            return (XAER_PROTO);
    }

    /*
     * At this point log->xa_first contains the point in the log
     * to which we need to roll back.  If we are starting a scan,
     * we'll start at the last record; if we're continuing a scan,
     * we'll have to start at log->xa_lsn.
     */

    memset(&data, 0, sizeof(data));
    for (err = log_get(log, &log->xa_lsn, &data,
        LF_ISSET(TMSTARTRSCAN) ? DB_LAST : DB_SET);
        err == 0 && log_compare(&log->xa_lsn, &log->xa_first) > 0;
        err = log_get(log, &log->xa_lsn, &data, DB_PREV)) {
        memcpy(&rectype, data.data, sizeof(rectype));

        /*
         * The only record type we care about is an DB_txn_xa_regop.
         * If it's a commit, we have to add it to a txnlist.  If it's
         * a prepare, and we don't have a commit, then we return it.
         * We are redoing some of what's in the xa_regop_recovery
         * code, but we have to do it here so we can get at the xid
         * in the record.
         */
        if (rectype != DB_txn_xa_regop && rectype != DB_txn_regop)
            continue;

        memcpy(&txnid, (u_int8_t *)data.data + sizeof(rectype),
            sizeof(txnid));
        err = __db_txnlist_find(log->xa_info, txnid);
        switch (rectype) {
        case DB_txn_regop:
            if (err == DB_NOTFOUND)
                __db_txnlist_add(log->xa_info, txnid);
            err = 0;
            break;
        case DB_txn_xa_regop:
            /*
             * This transaction is commited, so we needn't read
             * the record and do anything.
             */
            if (err == 0)
                break;
            if ((err =
                __txn_xa_regop_read(data.data, &argp)) != 0) {
                ret = XAER_RMERR;
                goto out;
            }

            xidp->formatID = argp->formatID;
            xidp->gtrid_length = argp->gtrid;
            xidp->bqual_length = argp->bqual;
            memcpy(xidp->data, argp->xid.data, argp->xid.size);
            ret++;
            xidp++;
            __os_free(argp, sizeof(*argp));
            if (ret == count)
                goto done;
            break;
        }
    }

    if (err != 0 && err != DB_NOTFOUND)
        goto out;

done:   if (LF_ISSET(TMENDRSCAN)) {
        ZERO_LSN(log->xa_lsn);
        ZERO_LSN(log->xa_first);

out:        __db_txnlist_end(log->xa_info);
        log->xa_info = NULL;
    }
    return (ret);

err3:   (void)__db_unmap_rmid(rmid);
err2:   (void)db_appexit(env);
err1:   __os_free(env, sizeof(DB_ENV));
    return (XAER_RMERR);
}

/*
 * __db_xa_rollback
 *  Abort an XA transaction.
 */
static int
__db_xa_rollback(xid, rmid, flags)
    XID *xid;
    int rmid;
    long flags;
{
    DB_ENV *env;
    TXN_DETAIL *td;
    size_t off;

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);
    if (flags != TMNOFLAGS)
        return (XAER_INVAL);

    if (__db_rmid_to_env(rmid, &env, 1) != 0)
        return (XAER_PROTO);

    if (__db_xid_to_txn(env, xid, &off) != 0)
        return (XAER_NOTA);

    td = (TXN_DETAIL *)((u_int8_t *)env->tx_info->region + off);

    if (td->xa_status == TXN_XA_DEADLOCKED)
        return (XA_RBDEADLOCK);

    if (td->xa_status == TXN_XA_ABORTED)
        return (XA_RBOTHER);

    if (LF_ISSET(TMONEPHASE) &&
        td->xa_status != TXN_XA_ENDED && td->xa_status != TXN_XA_SUSPENDED)
        return (XAER_PROTO);

    /* Now, fill in the global transaction structure. */
    __xa_txn_init(env, td, off);
    if (txn_abort(env->xa_txn) != 0)
        return (XAER_RMERR);

    /* No fatal value that would require an XAER_RMFAIL. */
    __xa_txn_end(env);
    return (XA_OK);
}

/*
 * __db_xa_forget --
 *  Forget about an XID for a transaction that was heuristically
 * completed.  Since we do not heuristically complete anything, I
 * don't think we have to do anything here, but we should make sure
 * that we reclaim the slots in the txnid table.
 */
static int
__db_xa_forget(xid, rmid, flags)
    XID *xid;
    int rmid;
    long flags;
{
    DB_ENV *env;
    size_t off;

    if (LF_ISSET(TMASYNC))
        return (XAER_ASYNC);
    if (flags != TMNOFLAGS)
        return (XAER_INVAL);

    if (__db_rmid_to_env(rmid, &env, 1) != 0)
        return (XAER_PROTO);

    /*
     * If mapping is gone, then we're done.
     */
    if (__db_xid_to_txn(env, xid, &off) != 0)
        return (XA_OK);

    __db_unmap_xid(env, xid, off);

    /* No fatal value that would require an XAER_RMFAIL. */
    return (XA_OK);
}

/*
 * __db_xa_complete --
 *  Used to wait for asynchronous operations to complete.  Since we're
 *  not doing asynch, this is an invalid operation.
 */
static int
__db_xa_complete(handle, retval, rmid, flags)
    int *handle, *retval, rmid;
    long flags;
{
    COMPQUIET(handle, NULL);
    COMPQUIET(retval, NULL);
    COMPQUIET(rmid, 0);
    COMPQUIET(flags, 0);

    return (XAER_INVAL);
}

/*
 * __xa_txn_init --
 *  Fill in the fields of the local transaction structure given
 *  the detail transaction structure.
 */
static void
__xa_txn_init(env, td, off)
    DB_ENV *env;
    TXN_DETAIL *td;
    size_t off;
{
    DB_TXN *txn;

    txn = env->xa_txn;
    txn->mgrp = env->tx_info;
    txn->parent = NULL;
    txn->last_lsn = td->last_lsn;
    txn->txnid = td->txnid;
    txn->off = off;
    txn->flags = 0;
}

/*
 * __xa_txn_end --
 *  Invalidate a transaction structure that was generated by xa_txn_init.
 */
static void
__xa_txn_end(env)
    DB_ENV *env;
{
    DB_TXN *txn;

    txn = env->xa_txn;
    if (txn != NULL)
        txn->txnid = TXN_INVALID;
}