SQLite

/*
** Return true if the given Btree is read-only.
*/
int sqlite3BtreeIsReadonly(Btree *p){
  return (p->pBt->btsFlags & BTS_READ_ONLY)!=0;
}

/*
** Return the size of the header added to each page by this module.
*/
int sqlite3HeaderSizeBtree(void){ return sizeof(MemPage); }

int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
void sqlite3BtreeIncrblobCursor(BtCursor *);
void sqlite3BtreeClearCursor(BtCursor *);
int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);
void sqlite3BtreeCursorHints(BtCursor *, unsigned int mask);
int sqlite3BtreeIsReadonly(Btree *pBt);
int sqlite3HeaderSizeBtree(void);

#ifndef NDEBUG
int sqlite3BtreeCursorIsValid(BtCursor*);
#endif

#ifndef SQLITE_OMIT_BTREECOUNT
int sqlite3BtreeCount(BtCursor *, i64 *);

    }
    case SQLITE_CONFIG_PAGECACHE: {
      /* Designate a buffer for page cache memory space */
      sqlite3GlobalConfig.pPage = va_arg(ap, void*);
      sqlite3GlobalConfig.szPage = va_arg(ap, int);
      sqlite3GlobalConfig.nPage = va_arg(ap, int);
      break;
    }
    case SQLITE_CONFIG_PCACHE_HDRSZ: {
      /* Return the total size of all headers added to each page
      ** of the page cache */
      *va_arg(ap, int*) = 
          sqlite3HeaderSizeBtree() +
          sqlite3HeaderSizePcache() +
          sqlite3HeaderSizePcache1();
      break;
    }

    case SQLITE_CONFIG_PCACHE: {
      /* no-op */
      break;
    }
    case SQLITE_CONFIG_GETPCACHE: {

/*
** Free up as much memory as possible from the page cache.
*/
void sqlite3PcacheShrink(PCache *pCache){
  assert( pCache->pCache!=0 );
  sqlite3GlobalConfig.pcache2.xShrink(pCache->pCache);
}

/*
** Return the size of the header added by this middleware layer
** in the page-cache hierarchy.
*/
int sqlite3HeaderSizePcache(void){ return sizeof(PgHdr); }


#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG)
/*
** For all dirty pages currently in the cache, invoke the specified
** callback. This is only used if the SQLITE_CHECK_PAGES macro is
** defined.
*/

#ifdef SQLITE_TEST
void sqlite3PcacheStats(int*,int*,int*,int*);
#endif

void sqlite3PCacheSetDefault(void);

/* Return the header size */
int sqlite3HeaderSizePcache(void);
int sqlite3HeaderSizePcache1(void);

#endif /* _PCACHE_H_ */

    pcache1Truncate,         /* xTruncate */
    pcache1Destroy,          /* xDestroy */
    pcache1Shrink            /* xShrink */
  };
  sqlite3_config(SQLITE_CONFIG_PCACHE2, &defaultMethods);
}

/*
** Return the size of the header on each page of this PCACHE implementation.
*/
int sqlite3HeaderSizePcache1(void){ return sizeof(PgHdr1); }

#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
/*
** This function is called to free superfluous dynamically allocated memory
** held by the pager system. Memory in use by any SQLite pager allocated
** by the current thread may be sqlite3_free()ed.
**
** nReq is the number of bytes of memory required. Once this much has

** fragmentation in low-memory embedded systems.
** </dd>
**
** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
** <dd> ^This option specifies a static memory buffer that SQLite can use for
** the database page cache with the default page cache implementation.  
** This configuration should not be used if an application-define page
** cache implementation is loaded using the [SQLITE_CONFIG_PCACHE2]
** configuration option.
** ^There are three arguments to this option: A pointer to 8-byte aligned
** memory, the size of each page buffer (sz), and the number of pages (N).
** The sz argument should be the size of the largest database page
** (a power of two between 512 and 32768) plus some extra bytes for each
** page header.  ^The number of extra bytes needed by the page header
** can be determined using the [SQLITE_CONFIG_PCACHE_HDRSZ] option 
** to [sqlite3_config()].
** ^It is harmless, apart from the wasted memory,
** for the sz parameter to be larger than necessary.  The first
** argument should pointer to an 8-byte aligned block of memory that
** is at least sz*N bytes of memory, otherwise subsequent behavior is
** undefined.
** ^SQLite will use the memory provided by the first argument to satisfy its
** memory needs for the first N pages that it adds to cache.  ^If additional
** page cache memory is needed beyond what is provided by this option, then
** SQLite goes to [sqlite3_malloc()] for the additional storage space.</dd>



**
** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
** <dd> ^This option specifies a static memory buffer that SQLite will use
** for all of its dynamic memory allocation needs beyond those provided
** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
** ^There are three arguments: An 8-byte aligned pointer to the memory,
** the number of bytes in the memory buffer, and the minimum allocation size.
** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
** to using its default memory allocator (the system malloc() implementation),
** undoing any prior invocation of [SQLITE_CONFIG_MALLOC].  ^If the
** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
** allocator is engaged to handle all of SQLites memory allocation needs.

** [[SQLITE_CONFIG_WIN32_HEAPSIZE]]
** <dt>SQLITE_CONFIG_WIN32_HEAPSIZE
** <dd>^This option is only available if SQLite is compiled for Windows
** with the [SQLITE_WIN32_MALLOC] pre-processor macro defined.
** SQLITE_CONFIG_WIN32_HEAPSIZE takes a 32-bit unsigned integer value
** that specifies the maximum size of the created heap.
** </dl>
**
** [[SQLITE_CONFIG_PCACHE_HDRSZ]]
** <dt>SQLITE_CONFIG_PCACHE_HDRSZ
** <dd>^This option takes a single parameter which is a pointer to an integer
** and writes into that integer the number of extra bytes per page required
** for each page in [SQLITE_CONFIG_PAGECACHE].  The amount of
** extra space required can change depending on the compiler,
** target platform, and SQLite version.
** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */

#define SQLITE_CONFIG_URI          17  /* int */
#define SQLITE_CONFIG_PCACHE2      18  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_GETPCACHE2   19  /* sqlite3_pcache_methods2* */
#define SQLITE_CONFIG_COVERING_INDEX_SCAN 20  /* int */
#define SQLITE_CONFIG_SQLLOG       21  /* xSqllog, void* */
#define SQLITE_CONFIG_MMAP_SIZE    22  /* sqlite3_int64, sqlite3_int64 */
#define SQLITE_CONFIG_WIN32_HEAPSIZE      23  /* int nByte */
#define SQLITE_CONFIG_PCACHE_HDRSZ        24  /* int *psz */

/*
** CAPI3REF: Database Connection Configuration Options
**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**