/*

** 2008 June 18

**

** 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.

**

*************************************************************************

**

** This module implements the sqlite3_status() interface and related

** functionality.

**

** $Id: status.c,v 1.9 2008/09/02 00:52:52 drh Exp $

*/

#include "sqliteInt.h"

/*

** Variables in which to record status information.

*/

typedef struct sqlite3StatType sqlite3StatType;

static SQLITE_WSD struct sqlite3StatType {

  int nowValue[9];         /* Current value */

  int mxValue[9];          /* Maximum value */

} sqlite3Stat = { {0,}, {0,} };

/* The "wsdStat" macro will resolve to the status information

** state vector.  If writable static data is unsupported on the target,

** we have to locate the state vector at run-time.  In the more common

** case where writable static data is supported, wsdStat can refer directly

** to the "sqlite3Stat" state vector declared above.

*/

#ifdef SQLITE_OMIT_WSD

# define wsdStatInit  sqlite3StatType *x = &GLOBAL(sqlite3StatType,sqlite3Stat)

# define wsdStat x[0]

#else

# define wsdStatInit

# define wsdStat sqlite3Stat

#endif

/*

** Return the current value of a status parameter.

*/

int sqlite3StatusValue(int op){

  wsdStatInit;

  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );

  return wsdStat.nowValue[op];

}

/*

** Add N to the value of a status record.  It is assumed that the

** caller holds appropriate locks.

*/

void sqlite3StatusAdd(int op, int N){

  wsdStatInit;

  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );

  wsdStat.nowValue[op] += N;

  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){

    wsdStat.mxValue[op] = wsdStat.nowValue[op];

  }

}

/*

** Set the value of a status to X.

*/

void sqlite3StatusSet(int op, int X){

  wsdStatInit;

  assert( op>=0 && op<ArraySize(wsdStat.nowValue) );

  wsdStat.nowValue[op] = X;

  if( wsdStat.nowValue[op]>wsdStat.mxValue[op] ){

    wsdStat.mxValue[op] = wsdStat.nowValue[op];

  }

}

/*

** Query status information.

**

** This implementation assumes that reading or writing an aligned

** 32-bit integer is an atomic operation.  If that assumption is not true,

** then this routine is not threadsafe.

*/

SQLITE_EXPORT int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag){

  wsdStatInit;

  if( op<0 || op>=ArraySize(wsdStat.nowValue) ){

    return SQLITE_MISUSE;

  }

  *pCurrent = wsdStat.nowValue[op];

  *pHighwater = wsdStat.mxValue[op];

  if( resetFlag ){

    wsdStat.mxValue[op] = wsdStat.nowValue[op];

  }

  return SQLITE_OK;

}

/*

** Query status information for a single database connection

*/

SQLITE_EXPORT int sqlite3_db_status(

  sqlite3 *db,          /* The database connection whose status is desired */

  int op,               /* Status verb */

  int *pCurrent,        /* Write current value here */

  int *pHighwater,      /* Write high-water mark here */

  int resetFlag         /* Reset high-water mark if true */

){

  switch( op ){

    case SQLITE_DBSTATUS_LOOKASIDE_USED: {

      *pCurrent = db->lookaside.nOut;

      *pHighwater = db->lookaside.mxOut;

      if( resetFlag ){

        db->lookaside.mxOut = db->lookaside.nOut;

      }

      break;

    }

    default: {

      return SQLITE_ERROR;

    }

  }

  return SQLITE_OK;

}