/*--- This software is copyrighted by the Regents of the University of California, and other parties. The following terms apply to all files associated with the software unless explicitly disclaimed in individual files. The authors hereby grant permission to use, copy, modify, distribute, and license this software and its documentation for any purpose, provided that existing copyright notices are retained in all copies and that this notice is included verbatim in any distributions. No written agreement, license, or royalty fee is required for any of the authorized uses. Modifications to this software may be copyrighted by their authors and need not follow the licensing terms described here, provided that the new terms are clearly indicated on the first page of each file where they apply. IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT. THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. GOVERNMENT USE: If you are acquiring this software on behalf of the U.S. government, the Government shall have only "Restricted Rights" in the software and related documentation as defined in the Federal Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2). If you are acquiring the software on behalf of the Department of Defense, the software shall be classified as "Commercial Computer Software" and the Government shall have only "Restricted Rights" as defined in Clause 252.227-7013 (c) (1) of DFARs. Notwithstanding the foregoing, the authors grant the U.S. Government and others acting in its behalf permission to use and distribute the software in accordance with the terms specified in this license. ---*/ /** * @file * Manages the page buffer bufferManager - Provides cached page handling, delegates to blob manager when necessary. Doesn't implement an eviction policy. That is left to a cacheManager. (Multiple cacheManagers could be used with a single bufferManager.) @todo Allow error checking! @todo Refactoring for lock manager Possible interface for lockManager: Define three classes of objects that the lock manager is interested in: Transactions, Operations, Predicates. Stasis already has operations and transactions, and these can be relatively unchanged. Predicates are read only operations that return a set of tuples. Tread() is the simplest predicate. Index scans provide a motivating example. See http://research.microsoft.com/%7Eadya/pubs/icde00.pdf (Generalized Isolation Level Definitions, Adya, Liskov, O'Neil, 2000) for a theoretical discussion of general locking schemes.. Locking functions can return errors such as DEADLOCK, etc. When such a value is returned, the transaction aborts, and an error is passed up to the application. @ingroup BUFFER_MANAGER * $Id$ */ #include #ifndef __BUFFERMANAGER_H__ #define __BUFFERMANAGER_H__ BEGIN_C_DECLS typedef struct Page_s Page_s; /** Page is defined in bufferManager.h as an incomplete type to enforce an abstraction barrier between page.h and the rest of the system. */ typedef struct Page_s Page; /** * Obtain a pointer to a page from the buffer manager. The page will * be pinned, and the pointer valid until releasePage is called. * * @param xid The transaction that is pinning the page (used by page-level locking implementations.) * * @param pageid ID of the page you want to load * * @return fully formed Page type */ Page * loadPage(int xid, pageid_t pageid); Page * loadUninitializedPage(int xid, pageid_t pageid); /** This is the function pointer that bufInit sets in order to override loadPage. */ extern Page * (*loadPageImpl)(int xid, pageid_t pageid); extern Page * (*loadUninitPageImpl)(int xid, pageid_t pageid); /** loadPage aquires a lock when it is called, effectively pinning it in memory. releasePage releases this lock. */ void releasePage(Page *p); /** This is the function pointer that bufInit sets in order to override releasePage. */ extern void (*releasePageImpl)(Page * p); /** * initialize buffer manager * @return 0 on success * @return error code on failure */ /** This is used by truncation to move dirty pages from Stasis cache into the operating system cache. Once writeBackPage(p) returns, calling forcePages() will synchronously force page number p to disk. (Not all buffer managers support synchronous writes to stable storage. For compatibility, such buffer managers should ignore this call.) */ extern void (*writeBackPage)(Page * p); /** Force any written back pages to disk. @see writeBackPage for more information. If the buffer manager doesn't support stable storage, this call is a no-op. */ extern void (*forcePages)(); /** Force written back pages that fall within a particular range to disk. This does not force page that have not been written to with pageWrite(). */ extern void (*forcePageRange)(pageid_t start, pageid_t stop); extern void (*simulateBufferManagerCrash)(); int bufInit(int type); /** * will write out any dirty pages, assumes that there are no running * transactions */ extern void (*bufDeinit)(); #ifdef PROFILE_LATCHES_WRITE_ONLY #define loadPage(x,y) __profile_loadPage((x), (y), __FILE__, __LINE__) #define releasePage(x) __profile_releasePage((x)) compensated_function void __profile_releasePage(Page * p); compensated_function Page * __profile_loadPage(int xid, pageid_t pageid, char * file, int line); #endif /*compensated_function Page * bufManLoadPage(int xid, int pageid); void bufManReleasePage(Page * p); int bufManBufInit(); void bufManBufDeinit(); void setBufferManager(int i); */ END_C_DECLS #endif