1 /*

     2 ** 2008 June 18

     3 **

     4 ** The author disclaims copyright to this source code.  In place of

     5 ** a legal notice, here is a blessing:

     6 **

     7 **    May you do good and not evil.

     8 **    May you find forgiveness for yourself and forgive others.

     9 **    May you share freely, never taking more than you give.

    10 **

    11 *************************************************************************

    12 **

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

    14 ** functionality.

    15 **

    16 ** $Id: status.c,v 1.7 2008/08/05 17:53:23 drh Exp $

    17 */

    18 #include "sqliteInt.h"

    19 

    20 /*

    21 ** Variables in which to record status information.

    22 */

    23 static struct {

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

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

    26 } sqlite3Stat;

    27 

    28 

    29 /*

    30 ** Reset the status records.  This routine is called by

    31 ** sqlite3_initialize().

    32 */

    33 void sqlite3StatusReset(void){

    34   memset(&sqlite3Stat, 0, sizeof(sqlite3Stat));

    35 }

    36 

    37 /*

    38 ** Return the current value of a status parameter.

    39 */

    40 int sqlite3StatusValue(int op){

    41   assert( op>=0 && op<ArraySize(sqlite3Stat.nowValue) );

    42   return sqlite3Stat.nowValue[op];

    43 }

    44 

    45 /*

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

    47 ** caller holds appropriate locks.

    48 */

    49 void sqlite3StatusAdd(int op, int N){

    50   assert( op>=0 && op<ArraySize(sqlite3Stat.nowValue) );

    51   sqlite3Stat.nowValue[op] += N;

    52   if( sqlite3Stat.nowValue[op]>sqlite3Stat.mxValue[op] ){

    53     sqlite3Stat.mxValue[op] = sqlite3Stat.nowValue[op];

    54   }

    55 }

    56 

    57 /*

    58 ** Set the value of a status to X.

    59 */

    60 void sqlite3StatusSet(int op, int X){

    61   assert( op>=0 && op<ArraySize(sqlite3Stat.nowValue) );

    62   sqlite3Stat.nowValue[op] = X;

    63   if( sqlite3Stat.nowValue[op]>sqlite3Stat.mxValue[op] ){

    64     sqlite3Stat.mxValue[op] = sqlite3Stat.nowValue[op];

    65   }

    66 }

    67 

    68 /*

    69 ** Query status information.

    70 **

    71 ** This implementation assumes that reading or writing an aligned

    72 ** 32-bit integer is an atomic operation.  If that assumption is not true,

    73 ** then this routine is not threadsafe.

    74 */

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

    76   if( op<0 || op>=ArraySize(sqlite3Stat.nowValue) ){

    77     return SQLITE_MISUSE;

    78   }

    79   *pCurrent = sqlite3Stat.nowValue[op];

    80   *pHighwater = sqlite3Stat.mxValue[op];

    81   if( resetFlag ){

    82     sqlite3Stat.mxValue[op] = sqlite3Stat.nowValue[op];

    83   }

    84   return SQLITE_OK;

    85 }

    86 

    87 /*

    88 ** Query status information for a single database connection

    89 */

    90 int sqlite3_db_status(

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

    92   int op,               /* Status verb */

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

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

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

    96 ){

    97   switch( op ){

    98     case SQLITE_DBSTATUS_LOOKASIDE_USED: {

    99       *pCurrent = db->lookaside.nOut;

   100       *pHighwater = db->lookaside.mxOut;

   101       if( resetFlag ){

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

   103       }

   104       break;

   105     }

   106     default: {

   107       return SQLITE_ERROR;

   108     }

   109   }

   110   return SQLITE_OK;

   111 }