SQLite

/*
** Return the number of references to the pager.
*/
int sqlite3PagerRefcount(Pager *pPager){
  return sqlite3PcacheRefCount(pPager->pPCache);
}

/*
** Return the approximate number of bytes of memory currently
** used by the pager and its associated cache.
*/
int sqlite3PagerMemUsed(Pager *pPager){
  int perPageSize = pPager->pageSize + pPager->nExtra + 20;
  return perPageSize*sqlite3PcachePagecount(pPager->pPCache)
           + sqlite3MallocSize(pPager);
}

/*
** Return the number of references to the specified page.
*/
int sqlite3PagerPageRefcount(DbPage *pPage){
  return sqlite3PcachePageRefcount(pPage);
}

int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
int sqlite3PagerSharedLock(Pager *pPager);

/* Functions used to query pager state and configuration. */
u8 sqlite3PagerIsreadonly(Pager*);
int sqlite3PagerRefcount(Pager*);
int sqlite3PagerMemUsed(Pager*);
const char *sqlite3PagerFilename(Pager*);
const sqlite3_vfs *sqlite3PagerVfs(Pager*);
sqlite3_file *sqlite3PagerFile(Pager*);
const char *sqlite3PagerJournalname(Pager*);
int sqlite3PagerNosync(Pager*);
void *sqlite3PagerTempSpace(Pager*);
int sqlite3PagerIsMemdb(Pager*);

/*
** CAPI3REF: Database Connection Status
**
** ^This interface is used to retrieve runtime status information 
** about a single [database connection].  ^The first argument is the
** database connection object to be interrogated.  ^The second argument
** is an integer constant, taken from the set of
** [SQLITE_DBSTATUS_LOOKASIDE_USED | SQLITE_DBSTATUS_*] macros, that
** determiness the parameter to interrogate.  The set of 
** [SQLITE_DBSTATUS_LOOKASIDE_USED | SQLITE_DBSTATUS_*] macros is likely
** to grow in future releases of SQLite.
**
** ^The current value of the requested parameter is written into *pCur
** and the highest instantaneous value is written into *pHiwtr.  ^If
** the resetFlg is true, then the highest instantaneous value is
** reset back down to the current value.
**
** See also: [sqlite3_status()] and [sqlite3_stmt_status()].

** The [sqlite3_db_status()] interface will return a non-zero error code
** if a discontinued or unsupported verb is invoked.
**
** <dl>
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
** <dd>This parameter returns the number of lookaside memory slots currently
** checked out.</dd>)^
**
** <dt>SQLITE_DBSTATUS_CACHE_USED</dt>
** <dd>^This parameter returns the approximate number of of bytes of heap
** memory used by all pager caches associated with the database connection.
** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
** checked out.</dd>)^
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED     0
#define SQLITE_DBSTATUS_CACHE_USED         1
#define SQLITE_DBSTATUS_MAX                1   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status
**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS_SORT | counters] that measure the number

      *pCurrent = db->lookaside.nOut;
      *pHighwater = db->lookaside.mxOut;
      if( resetFlag ){
        db->lookaside.mxOut = db->lookaside.nOut;
      }
      break;
    }

    /* 
    ** Return an approximation for the amount of memory currently used
    ** by all pagers associated with the given database connection.  The
    ** highwater mark is meaningless and is returned as zero.
    */
    case SQLITE_DBSTATUS_CACHE_USED: {
      int totalUsed = 0;
      int i;
      for(i=0; i<db->nDb; i++){
        Btree *pBt = db->aDb[i].pBt;
        if( pBt ){
          Pager *pPager = sqlite3BtreePager(pBt);
          totalUsed += sqlite3PagerMemUsed(pPager);
        }
      }
      *pCurrent = totalUsed;
      *pHighwater = 0;
      break;
    }
    default: {
      return SQLITE_ERROR;
    }
  }
  return SQLITE_OK;
}

  sqlite3 *db;
  int getDbPointer(Tcl_Interp*, const char*, sqlite3**);
  static const struct {
    const char *zName;
    int op;
  } aOp[] = {
    { "SQLITE_DBSTATUS_LOOKASIDE_USED",    SQLITE_DBSTATUS_LOOKASIDE_USED   },
    { "SQLITE_DBSTATUS_CACHE_USED",        SQLITE_DBSTATUS_CACHE_USED       },
  };
  Tcl_Obj *pResult;
  if( objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "PARAMETER RESETFLAG");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;

# 2010 March 10
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# Tests for the sqlite3_db_status() function
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl


# Make sure sqlite3_db_config() and sqlite3_db_status are working.
#
unset -nocomplain PAGESZ
unset -nocomplain BASESZ
do_test dbstatus-1.1 {
  db close
  sqlite3 db :memory:
  db eval {
    CREATE TABLE t1(x);
  }
  set sz1 [lindex [sqlite3_db_status db SQLITE_DBSTATUS_CACHE_USED 0] 1]
  db eval {
    CREATE TABLE t2(y);
  }
  set sz2 [lindex [sqlite3_db_status db SQLITE_DBSTATUS_CACHE_USED 0] 1]
  set ::PAGESZ [expr {$sz2-$sz1}]
  set ::BASESZ [expr {$sz1-$::PAGESZ}]
  expr {$::PAGESZ>1024 && $::PAGESZ<1200}
} {1}
do_test dbstatus-1.2 {
  db eval {
    INSERT INTO t1 VALUES(zeroblob(9000));
  }
  lindex [sqlite3_db_status db SQLITE_DBSTATUS_CACHE_USED 0] 1
} [expr {$BASESZ + 10*$PAGESZ}]

finish_test