xa.c

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/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1998, 1999, 2000
 *      Sleepycat Software.  All rights reserved.
 */

#include "config.h"

#ifndef lint
static const char revid[] = "$Id: xa_8c-source.html,v 1.1 2008/06/08 10:25:38 sebdiaz Exp $";
#endif /* not lint */

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

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

#include "db_int.h"
#include "db_page.h"
#include "log.h"
#include "txn.h"
#include "db_am.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 CDB_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 CDB_db_env_create, any config information
 * will have to be done via a config file instead of via the CDB_db_env_create
 * 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 (CDB___db_rmid_to_env(rmid, &env) == 0)
                return (XA_OK);
        if (CDB___os_calloc(env, 1, sizeof(DB_ENV), &env) != 0)
                return (XAER_RMERR);

        /* Open a new environment. */
#define XA_FLAGS \
        DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN
        if (CDB_db_env_create(&env, 0) != 0)
                return (XAER_RMERR);
        if (env->open(env, xa_info, XA_FLAGS, 0) != 0)
                goto err;

        /* Create the mapping. */
        if (CDB___db_map_rmid(rmid, env) != 0)
                goto err;

        /* Allocate space for the current transaction. */
        if (CDB___os_calloc(env, 1, sizeof(DB_TXN), &env->xa_txn) != 0)
                goto err;
        env->xa_txn->txnid = TXN_INVALID;

        return (XA_OK);

err:    (void)env->close(env, 0);

        return (XAER_RMERR);
}

/*
 * __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 (CDB___db_rmid_to_env(rmid, &env) != 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);

        /* Destroy the mapping. */
        ret = CDB___db_unmap_rmid(rmid);

        /* Discard space held for the current transaction. */
        if (env->xa_txn != NULL)
                CDB___os_free(env->xa_txn, sizeof(DB_TXN));

        /* Close the environment. */
        if ((t_ret = env->close(env, 0)) != 0 && ret == 0)
                ret = t_ret;

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

        is_known = CDB___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 *)
                    R_ADDR(&((DB_TXNMGR *)env->tx_handle)->reginfo, off);
                if (td->xa_status == TXN_XA_SUSPENDED &&
                    !LF_ISSET(TMRESUME | TMJOIN))
                        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 (CDB___txn_xa_begin(env, env->xa_txn) != 0)
                        return (XAER_RMERR);
                (void)CDB___db_map_xid(env, xid, env->xa_txn->off);
                td = (TXN_DETAIL *)
                    R_ADDR(&((DB_TXNMGR *)env->tx_handle)->reginfo,
                    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 (CDB___db_rmid_to_env(rmid, &env) != 0)
                return (XAER_PROTO);

        if (CDB___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 *)R_ADDR(&((DB_TXNMGR *)env->tx_handle)->reginfo, 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 (CDB___db_rmid_to_env(rmid, &env) != 0)
                return (XAER_PROTO);

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

        td = (TXN_DETAIL *)R_ADDR(&((DB_TXNMGR *)env->tx_handle)->reginfo, 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 (CDB_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 (CDB___db_rmid_to_env(rmid, &env) != 0)
                return (XAER_PROTO);

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

        td = (TXN_DETAIL *)R_ADDR(&((DB_TXNMGR *)env->tx_handle)->reginfo, 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 (CDB_txn_commit(env->xa_txn, 0) != 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;
        int err, ret;
        u_int32_t rectype, txnid;

        ret = 0;
        xidp = xids;

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

        /*
         * If we are starting a scan, then we need to figure out where
         * to begin.  If we are not starting a scan, 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.
         */
        log = env->lg_handle;
        if (LF_ISSET(TMSTARTRSCAN)) {
                if ((err = CDB___log_findckp(env, &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 = CDB___db_txnlist_init(env, &log->xa_info)) != 0)
                        return (XAER_RMERR);
        } else {
                /*
                 * If we are not starting a scan, the log cursor had
                 * better be set.
                 */
                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 = CDB_log_get(env, &log->xa_lsn, &data,
            LF_ISSET(TMSTARTRSCAN) ? DB_LAST : DB_SET);
            err == 0 && CDB_log_compare(&log->xa_lsn, &log->xa_first) > 0;
            err = CDB_log_get(env, &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 = CDB___db_txnlist_find(log->xa_info, txnid);
                switch (rectype) {
                case DB_txn_regop:
                        if (err == DB_NOTFOUND)
                                CDB___db_txnlist_add(env, log->xa_info, txnid);
                        err = 0;
                        break;
                case DB_txn_xa_regop:
                        /*
                         * This transaction is committed, so we needn't read
                         * the record and do anything.
                         */
                        if (err == 0)
                                break;
                        if ((err =
                            CDB___txn_xa_regop_read(env, 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++;
                        CDB___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:            CDB___db_txnlist_end(env, log->xa_info);
                log->xa_info = NULL;
        }
        return (ret);
}

/*
 * __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 (CDB___db_rmid_to_env(rmid, &env) != 0)
                return (XAER_PROTO);

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

        td = (TXN_DETAIL *)R_ADDR(&((DB_TXNMGR *)env->tx_handle)->reginfo, off);
        if (td->xa_status == TXN_XA_DEADLOCKED)
                return (XA_RBDEADLOCK);

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

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

        /* Now, fill in the global transaction structure. */
        __xa_txn_init(env, td, off);
        if (CDB_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 (CDB___db_rmid_to_env(rmid, &env) != 0)
                return (XAER_PROTO);

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

        CDB___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_handle;
        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;
}

---