180 lines
6 KiB
C
180 lines
6 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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* Manages the page buffer
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bufferManager - Provides cached page handling, delegates to blob
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manager when necessary. Doesn't implement an eviction policy.
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That is left to a cacheManager. (Multiple cacheManagers could be
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used with a single bufferManager.)
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@todo Allow error checking!
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@todo Refactoring for lock manager
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Possible interface for lockManager:
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Define three classes of objects that the lock manager is interested in:
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Transactions,
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Operations,
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Predicates.
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Stasis already has operations and transactions, and these can be
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relatively unchanged. Predicates are read only operations that
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return a set of tuples. Tread() is the simplest predicate.
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Index scans provide a motivating example.
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See http://research.microsoft.com/%7Eadya/pubs/icde00.pdf
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(Generalized Isolation Level Definitions, Adya, Liskov, O'Neil,
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2000) for a theoretical discussion of general locking schemes..
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Locking functions can return errors such as DEADLOCK, etc.
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When such a value is returned, the transaction aborts, and an
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error is passed up to the application.
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* @ingroup LLADD_CORE
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* $Id$
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*/
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#include <lladd/constants.h>
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#include <lladd/transactional.h>
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#ifndef __BUFFERMANAGER_H__
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#define __BUFFERMANAGER_H__
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BEGIN_C_DECLS
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/**
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Page is defined in bufferManager.h as an incomplete type to enforce
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an abstraction barrier between page.h and the rest of the system.
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If you need to muck with page internals, first consider the
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implications that doing so has on latching. In particular, rwlatch
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is currently entirely handled in page.c.
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*/
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typedef struct Page_s Page_s;
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typedef struct Page_s Page;
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/**
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This is the type of buffer manager that is being used.
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Before Stasis is intialized, it will be set to a default value.
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It may be changed before Tinit() is called, or overridden at
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compile time by defining USE_BUFFER_MANAGER
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(eg: gcc ... -DUSE_BUFFER_MANAGER=BUFFER_MANAGER_FOO)
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@see constants.h for a list of recognized log implementations.
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*/
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extern int bufferManagerType;
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/**
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* @param xid The transaction that is pinning the page (used by page-level locking implementations.)
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* @param pageid ID of the page you want to load
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* @return fully formed Page type
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*/
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extern Page * (*loadPage)(int xid, int pageid);
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/**
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loadPage aquires a lock when it is called, effectively pinning it
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in memory. releasePage releases this lock.
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*/
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extern void (*releasePage)(Page * p);
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/**
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* initialize buffer manager
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* @return 0 on success
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* @return error code on failure
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*/
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/**
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This is used by truncation to move dirty pages from Stasis cache
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into the operating system cache. Once writeBackPage(p) returns,
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calling forcePages() will synchronously force page number p to
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disk.
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(Not all buffer managers support synchronous writes to stable
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storage. For compatibility, such buffer managers should ignore
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this call.)
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*/
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extern void (*writeBackPage)(Page * p);
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/**
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Force any written back pages to disk.
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@see writeBackPage for more information.
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If the buffer manager doesn't support stable storage, this call is
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a no-op.
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*/
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extern void (*forcePages)();
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extern void (*simulateBufferManagerCrash)();
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int bufInit(int type);
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/**
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* will write out any dirty pages, assumes that there are no running
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* transactions
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*/
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extern void (*bufDeinit)();
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#ifdef PROFILE_LATCHES_WRITE_ONLY
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#define loadPage(x,y) __profile_loadPage((x), (y), __FILE__, __LINE__)
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#define releasePage(x) __profile_releasePage((x))
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compensated_function void __profile_releasePage(Page * p);
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compensated_function Page * __profile_loadPage(int xid, int pageid, char * file, int line);
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#endif
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/*compensated_function Page * bufManLoadPage(int xid, int pageid);
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void bufManReleasePage(Page * p);
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int bufManBufInit();
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void bufManBufDeinit();
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void setBufferManager(int i); */
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END_C_DECLS
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#endif
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