105 lines
4.2 KiB
C
105 lines
4.2 KiB
C
/*---
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This software is copyrighted by the Regents of the University of
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California, and other parties. The following terms apply to all files
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associated with the software unless explicitly disclaimed in
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individual files.
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The authors hereby grant permission to use, copy, modify, distribute,
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and license this software and its documentation for any purpose,
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provided that existing copyright notices are retained in all copies
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and that this notice is included verbatim in any distributions. No
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written agreement, license, or royalty fee is required for any of the
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authorized uses. Modifications to this software may be copyrighted by
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their authors and need not follow the licensing terms described here,
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provided that the new terms are clearly indicated on the first page of
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each file where they apply.
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IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
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FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
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DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND
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NON-INFRINGEMENT. THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, AND
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THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
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MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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GOVERNMENT USE: If you are acquiring this software on behalf of the
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U.S. government, the Government shall have only "Restricted Rights" in
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the software and related documentation as defined in the Federal
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Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2). If you are
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acquiring the software on behalf of the Department of Defense, the
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software shall be classified as "Commercial Computer Software" and the
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Government shall have only "Restricted Rights" as defined in Clause
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252.227-7013 (c) (1) of DFARs. Notwithstanding the foregoing, the
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authors grant the U.S. Government and others acting in its behalf
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permission to use and distribute the software in accordance with the
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terms specified in this license.
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---*/
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#include <lladd/logger/logger2.h>
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/*#include "logEntry.h"
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#include "logWriter.h" */
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#ifndef __LOGHANDLE_H
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#define __LOGHANDLE_H
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BEGIN_C_DECLS
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/**
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@file
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A simple data structure that allows forward iterations over
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the log, and also allows reverse iterations. Forward iterations
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are used for redo, and return every log entry, in its original
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order. Reverse iterations are used for undo, and are transaction
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specific. They follow the prevLSN. (or the next entry to be
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undone stored in any CLR's that are encountered.)
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logHandle is useful for read only access to the log.
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@see logWriter.h For write access to the log.
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@see logger2.h for the typedef of the logHandle struct
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*/
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/** Returns a logHandle pointing at the first log entry in the log. */
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LogHandle getLogHandle();
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/** Returns a logHandle pointing at lsn. */
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LogHandle getLSNHandle(lsn_t lsn);
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/** Returns a 'guarded log handle'. This handle executes a callback
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function on each entry it encounters. If the guard returns 0,
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then it's iterator terminates. Otherwise, it behaves normally. */
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LogHandle getGuardedHandle(lsn_t lsn, guard_fcn_t * f, void * guard_state);
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/**
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@return a pointer to the next log entry in the log, or NULL if at
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EOF.
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*/
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LogEntry * nextInLog(LogHandle * h);
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/**
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Returns a pointer to the previous log entry in this
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transaction. This is used to undo transactions. If the logHandle
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is a guarded handle, the handle returns null.
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The guard is useful for Tprepare, partial rollback, and probably
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any reasonable lock manager implementations.
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If we encounter a CLR, that means that everything after the clr's
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undoNextLSN has already been undone. In that case, we can skip
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all intervening log entries (including CLR's), since they contain
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'stale' data.
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@return NULL if there is no previous LogEntry for this
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transaction, or if the guard indicates that we're done by returning 0.
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*/
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LogEntry * previousInTransaction(LogHandle * h);
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/*
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void closeHandle(LogHandle h);
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*/
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END_C_DECLS
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#endif
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