pager.c

1.编译色情sqlite源代码为dll；2.运用sqlite3数据库存储二进制数据到数据库

  u8 setMaster;               /* True if a m-j name has been written to jrnl */
  u8 doNotSync;               /* Boolean. While true, do not spill the cache */
  u8 exclusiveMode;           /* Boolean. True if locking_mode==EXCLUSIVE */
  u8 changeCountDone;         /* Set after incrementing the change-counter */
  u32 vfsFlags;               /* Flags for sqlite3_vfs.xOpen() */
  int errCode;                /* One of several kinds of errors */
  int dbSize;                 /* Number of pages in the file */
  int origDbSize;             /* dbSize before the current change */
  int stmtSize;               /* Size of database (in pages) at stmt_begin() */
  int nRec;                   /* Number of pages written to the journal */
  u32 cksumInit;              /* Quasi-random value added to every checksum */
  int stmtNRec;               /* Number of records in stmt subjournal */
  int nExtra;                 /* Add this many bytes to each in-memory page */
  int pageSize;               /* Number of bytes in a page */
  int nPage;                  /* Total number of in-memory pages */
  int nRef;                   /* Number of in-memory pages with PgHdr.nRef>0 */
  int mxPage;                 /* Maximum number of pages to hold in cache */
  Pgno mxPgno;                /* Maximum allowed size of the database */
  u8 *aInJournal;             /* One bit for each page in the database file */
  u8 *aInStmt;                /* One bit for each page in the database */
  char *zFilename;            /* Name of the database file */
  char *zJournal;             /* Name of the journal file */
  char *zDirectory;           /* Directory hold database and journal files */
  char *zStmtJrnl;            /* Name of the statement journal file */
  sqlite3_file *fd, *jfd;     /* File descriptors for database and journal */
  sqlite3_file *stfd;         /* File descriptor for the statement subjournal*/
  BusyHandler *pBusyHandler;  /* Pointer to sqlite.busyHandler */
  PagerLruList lru;           /* LRU list of free pages */
  PgHdr *pAll;                /* List of all pages */
  PgHdr *pStmt;               /* List of pages in the statement subjournal */
  PgHdr *pDirty;              /* List of all dirty pages */
  i64 journalOff;             /* Current byte offset in the journal file */
  i64 journalHdr;             /* Byte offset to previous journal header */
  i64 stmtHdrOff;             /* First journal header written this statement */
  i64 stmtCksum;              /* cksumInit when statement was started */
  i64 stmtJSize;              /* Size of journal at stmt_begin() */
  int sectorSize;             /* Assumed sector size during rollback */
#ifdef SQLITE_TEST
  int nHit, nMiss;            /* Cache hits and missing */
  int nRead, nWrite;          /* Database pages read/written */
#endif
  void (*xDestructor)(DbPage*,int); /* Call this routine when freeing pages */
  void (*xReiniter)(DbPage*,int);   /* Call this routine when reloading pages */
#ifdef SQLITE_HAS_CODEC
  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
  void *pCodecArg;            /* First argument to xCodec() */
#endif
  int nHash;                  /* Size of the pager hash table */
  PgHdr **aHash;              /* Hash table to map page number to PgHdr */
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  Pager *pNext;               /* Doubly linked list of pagers on which */
  Pager *pPrev;               /* sqlite3_release_memory() will work */
  int iInUseMM;               /* Non-zero if unavailable to MM */
  int iInUseDB;               /* Non-zero if in sqlite3_release_memory() */
#endif
  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */
  char dbFileVers[16];        /* Changes whenever database file changes */
};

/*
** The following global variables hold counters used for
** testing purposes only.  These variables do not exist in
** a non-testing build.  These variables are not thread-safe.
*/
#ifdef SQLITE_TEST
int sqlite3_pager_readdb_count = 0;    /* Number of full pages read from DB */
int sqlite3_pager_writedb_count = 0;   /* Number of full pages written to DB */
int sqlite3_pager_writej_count = 0;    /* Number of pages written to journal */
int sqlite3_pager_pgfree_count = 0;    /* Number of cache pages freed */
# define PAGER_INCR(v)  v++
#else
# define PAGER_INCR(v)
#endif

/*
** The following variable points to the head of a double-linked list
** of all pagers that are eligible for page stealing by the
** sqlite3_release_memory() interface.  Access to this list is
** protected by the SQLITE_MUTEX_STATIC_MEM2 mutex.
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
static Pager *sqlite3PagerList = 0;
static PagerLruList sqlite3LruPageList = {0, 0, 0};
#endif


/*
** Journal files begin with the following magic string.  The data
** was obtained from /dev/random.  It is used only as a sanity check.
**
** Since version 2.8.0, the journal format contains additional sanity
** checking information.  If the power fails while the journal is begin
** written, semi-random garbage data might appear in the journal
** file after power is restored.  If an attempt is then made
** to roll the journal back, the database could be corrupted.  The additional
** sanity checking data is an attempt to discover the garbage in the
** journal and ignore it.
**
** The sanity checking information for the new journal format consists
** of a 32-bit checksum on each page of data.  The checksum covers both
** the page number and the pPager->pageSize bytes of data for the page.
** This cksum is initialized to a 32-bit random value that appears in the
** journal file right after the header.  The random initializer is important,
** because garbage data that appears at the end of a journal is likely
** data that was once in other files that have now been deleted.  If the
** garbage data came from an obsolete journal file, the checksums might
** be correct.  But by initializing the checksum to random value which
** is different for every journal, we minimize that risk.
*/
static const unsigned char aJournalMagic[] = {
  0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
};

/*
** The size of the header and of each page in the journal is determined
** by the following macros.
*/
#define JOURNAL_PG_SZ(pPager)  ((pPager->pageSize) + 8)

/*
** The journal header size for this pager. In the future, this could be
** set to some value read from the disk controller. The important
** characteristic is that it is the same size as a disk sector.
*/
#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)

/*
** The macro MEMDB is true if we are dealing with an in-memory database.
** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
** the value of MEMDB will be a constant and the compiler will optimize
** out code that would never execute.
*/
#ifdef SQLITE_OMIT_MEMORYDB
# define MEMDB 0
#else
# define MEMDB pPager->memDb
#endif

/*
** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
** reserved for working around a windows/posix incompatibility). It is
** used in the journal to signify that the remainder of the journal file 
** is devoted to storing a master journal name - there are no more pages to
** roll back. See comments for function writeMasterJournal() for details.
*/
/* #define PAGER_MJ_PGNO(x) (PENDING_BYTE/((x)->pageSize)) */
#define PAGER_MJ_PGNO(x) ((PENDING_BYTE/((x)->pageSize))+1)

/*
** The maximum legal page number is (2^31 - 1).
*/
#define PAGER_MAX_PGNO 2147483647

/*
** The pagerEnter() and pagerLeave() routines acquire and release
** a mutex on each pager.  The mutex is recursive.
**
** This is a special-purpose mutex.  It only provides mutual exclusion
** between the Btree and the Memory Management sqlite3_release_memory()
** function.  It does not prevent, for example, two Btrees from accessing
** the same pager at the same time.  Other general-purpose mutexes in
** the btree layer handle that chore.
*/
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  static void pagerEnter(Pager *p){
    p->iInUseDB++;
    if( p->iInUseMM && p->iInUseDB==1 ){
      sqlite3_mutex *mutex;
      mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM2);
      p->iInUseDB = 0;
      sqlite3_mutex_enter(mutex);
      p->iInUseDB = 1;
      sqlite3_mutex_leave(mutex);
    }
    assert( p->iInUseMM==0 );
  }
  static void pagerLeave(Pager *p){
    p->iInUseDB--;
    assert( p->iInUseDB>=0 );
  }
#else
# define pagerEnter(X)
# define pagerLeave(X)
#endif

/*
** Add page pPg to the end of the linked list managed by structure
** pList (pPg becomes the last entry in the list - the most recently 
** used). Argument pLink should point to either pPg->free or pPg->gfree,
** depending on whether pPg is being added to the pager-specific or
** global LRU list.
*/
static void listAdd(PagerLruList *pList, PagerLruLink *pLink, PgHdr *pPg){
  pLink->pNext = 0;
  pLink->pPrev = pList->pLast;

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  assert(pLink==&pPg->free || pLink==&pPg->gfree);
  assert(pLink==&pPg->gfree || pList!=&sqlite3LruPageList);
#endif

  if( pList->pLast ){
    int iOff = (char *)pLink - (char *)pPg;
    PagerLruLink *pLastLink = (PagerLruLink *)(&((u8 *)pList->pLast)[iOff]);
    pLastLink->pNext = pPg;
  }else{
    assert(!pList->pFirst);
    pList->pFirst = pPg;
  }

  pList->pLast = pPg;
  if( !pList->pFirstSynced && pPg->needSync==0 ){
    pList->pFirstSynced = pPg;
  }
}

/*
** Remove pPg from the list managed by the structure pointed to by pList.
**
** Argument pLink should point to either pPg->free or pPg->gfree, depending 
** on whether pPg is being added to the pager-specific or global LRU list.
*/
static void listRemove(PagerLruList *pList, PagerLruLink *pLink, PgHdr *pPg){
  int iOff = (char *)pLink - (char *)pPg;

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  assert(pLink==&pPg->free || pLink==&pPg->gfree);
  assert(pLink==&pPg->gfree || pList!=&sqlite3LruPageList);
#endif

  if( pPg==pList->pFirst ){
    pList->pFirst = pLink->pNext;
  }
  if( pPg==pList->pLast ){
    pList->pLast = pLink->pPrev;
  }
  if( pLink->pPrev ){
    PagerLruLink *pPrevLink = (PagerLruLink *)(&((u8 *)pLink->pPrev)[iOff]);
    pPrevLink->pNext = pLink->pNext;
  }
  if( pLink->pNext ){
    PagerLruLink *pNextLink = (PagerLruLink *)(&((u8 *)pLink->pNext)[iOff]);
    pNextLink->pPrev = pLink->pPrev;
  }
  if( pPg==pList->pFirstSynced ){
    PgHdr *p = pLink->pNext;
    while( p && p->needSync ){
      PagerLruLink *pL = (PagerLruLink *)(&((u8 *)p)[iOff]);
      p = pL->pNext;
    }
    pList->pFirstSynced = p;
  }

  pLink->pNext = pLink->pPrev = 0;
}

/* 
** Add page pPg to the list of free pages for the pager. If 
** memory-management is enabled, also add the page to the global 
** list of free pages.
*/
static void lruListAdd(PgHdr *pPg){
  listAdd(&pPg->pPager->lru, &pPg->free, pPg);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  if( !pPg->pPager->memDb ){
    sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
    listAdd(&sqlite3LruPageList, &pPg->gfree, pPg);
    sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
  }
#endif
}

/* 
** Remove page pPg from the list of free pages for the associated pager.
** If memory-management is enabled, also remove pPg from the global list
** of free pages.
*/
static void lruListRemove(PgHdr *pPg){
  listRemove(&pPg->pPager->lru, &pPg->free, pPg);
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  if( !pPg->pPager->memDb ){
    sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
    listRemove(&sqlite3LruPageList, &pPg->gfree, pPg);
    sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
  }
#endif
}

/* 
** This function is called just after the needSync flag has been cleared
** from all pages managed by pPager (usually because the journal file
** has just been synced). It updates the pPager->lru.pFirstSynced variable
** and, if memory-management is enabled, the sqlite3LruPageList.pFirstSynced
** variable also.
*/
static void lruListSetFirstSynced(Pager *pPager){
  pPager->lru.pFirstSynced = pPager->lru.pFirst;
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  if( !pPager->memDb ){
    PgHdr *p;
    sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
    for(p=sqlite3LruPageList.pFirst; p && p->needSync; p=p->gfree.pNext);
    assert(p==pPager->lru.pFirstSynced || p==sqlite3LruPageList.pFirstSynced);
    sqlite3LruPageList.pFirstSynced = p;
    sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU));
  }
#endif
}

/*
** Return true if page *pPg has already been written to the statement
** journal (or statement snapshot has been created, if *pPg is part
** of an in-memory database).
*/
static int pageInStatement(PgHdr *pPg){
  Pager *pPager = pPg->pPager;
  if( MEMDB ){
    return PGHDR_TO_HIST(pPg, pPager)->inStmt;
  }else{
    Pgno pgno = pPg->pgno;
    u8 *a = pPager->aInStmt;
    return (a && (int)pgno<=pPager->stmtSize && (a[pgno/8] & (1<<(pgno&7))));
  }
}

/*
** Change the size of the pager hash table to N.  N must be a power
** of two.
*/
static void pager_resize_hash_table(Pager *pPager, int N){
  PgHdr **aHash, *pPg;
  assert( N>0 && (N&(N-1))==0 );
  pagerLeave(pPager);
  sqlite3FaultBenign(SQLITE_FAULTINJECTOR_MALLOC, pPager->aHash!=0);
  aHash = sqlite3MallocZero( sizeof(aHash[0])*N );
  sqlite3FaultBenign(SQLITE_FAULTINJECTOR_MALLOC, 0);
  pagerEnter(pPager);
  if( aHash==0 ){
    /* Failure to rehash is not an error.  It is only a performance hit. */
    return;
  }
  sqlite3_free(pPager->aHash);
  pPager->nHash = N;
  pPager->aHash = aHash;
  for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
    int h;
    if( pPg->pgno==0 ){
      assert( pPg->pNextHash==0 && pPg->pPrevHash==0 );
      continue;