158 lines
5 KiB
C
158 lines
5 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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/**
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* @file
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*
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* New version of logstreamer; designed to work with logEntry, and has
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* a simplified API.
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*
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* logstreamer is the implementation of writing the log tail
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* It must be bufferred -- in that when something is written to the log tail it
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* is not immediately written to disk, but rather just to memory. But
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* logstreamer must be able to force flush to disk, which will be done when a
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* commit log entry is written to the log tail
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*
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* Note: using the stdio FILEs for this, and by default it is "fully" buffered.
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* The log tail may be flushed to disk without an explicit call to fflush (when
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* the program terminates, the file closes), but this is acceptable because it
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* never hurts to have more flushes to disk, as long as it doesn't hurt
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* performance.
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*
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* @todo Everything in this file cores on failure (no error handling yet)
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* @todo All of the logWriter calls should be reentrant.
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*
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* $Id$
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*
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*/
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#ifndef __LOGWRITER_H__
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#define __LOGWRITER_H__
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#include "logEntry.h"
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#include <lladd/constants.h>
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#include <lladd/common.h>
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BEGIN_C_DECLS
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/**
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start a new log stream by opening the log file for reading
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returns 0 on success, or an error code define above
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*/
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int openLogWriter();
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/**
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@param e Pointer to a log entry. After the call, e->LSN will be set appropriately.
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returns 0 on success, or an error code defined above
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*/
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int writeLogEntry(LogEntry * e);
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/*
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flush the entire log (tail) that is currently in memory to disk
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*/
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void syncLog();
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/*
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Close the log stream
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*/
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void closeLogWriter();
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/*
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Get the current position of the stream (in terms of bytes)
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*/
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/*long getFilePos();*/
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/*
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Actually deletes the log file that may have been written to disk! Danger!!
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Only use after calling closeLogStream AND you are sure there are no active (or
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future active) transactions!
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*/
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void deleteLogWriter();
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/*
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* Returns the current position of the stream no matter where it is
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*/
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/*long streamPos();*/
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/*
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* Returns the position of the stream if it were to read.
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*/
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/*long writeStreamPos();*/
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/*
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* readLog reads a line from the log puts it in a string
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*
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* This was made static because it exports state that the interface
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* should be hiding. (To use this function, the user must make
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* assumptions regarding the value of the FILE's current offset.)
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*
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* returns the number of bytes read and put into buffer
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* */
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/*int readLog(byte **buffer);*/
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/* LogEntry * readLogEntry(); */
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/*
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* seek to a position in the log file and read it into the buffer
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*
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* returns the number of bytes read and put into buffer
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* */
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/*int seekAndReadLog(long pos, byte **buffer);*/
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LogEntry * readLSNEntry(lsn_t LSN);
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/* lsn_t nextLSN(); */
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/*
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* tell the current position in the log file
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* */
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/*long readPos ();
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void seekInLog(long pos);*/
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END_C_DECLS
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#endif /* __LLADD_LOGGER_LOGWRITER_H */
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