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 1.9 2008/09/02 00:52:52 drh Exp $

    17 */

    18 #include "sqliteInt.h"

    19 

    20 /*

    21 ** Variables in which to record status information.

    22 */

    23 typedef struct sqlite3StatType sqlite3StatType;

    24 static SQLITE_WSD struct sqlite3StatType {

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

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

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

    28 

    29 

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

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

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

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

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

    35 */

    36 #ifdef SQLITE_OMIT_WSD

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

    38 # define wsdStat x[0]

    39 #else

    40 # define wsdStatInit

    41 # define wsdStat sqlite3Stat

    42 #endif

    43 

    44 /*

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

    46 */

    47 int sqlite3StatusValue(int op){

    48   wsdStatInit;

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

    50   return wsdStat.nowValue[op];

    51 }

    52 

    53 /*

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

    55 ** caller holds appropriate locks.

    56 */

    57 void sqlite3StatusAdd(int op, int N){

    58   wsdStatInit;

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

    60   wsdStat.nowValue[op] += N;

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

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

    63   }

    64 }

    65 

    66 /*

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

    68 */

    69 void sqlite3StatusSet(int op, int X){

    70   wsdStatInit;

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

    72   wsdStat.nowValue[op] = X;

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

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

    75   }

    76 }

    77 

    78 /*

    79 ** Query status information.

    80 **

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

    82 ** 32-bit integer is an atomic operation.  If that assumption is not true,

    83 ** then this routine is not threadsafe.

    84 */

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

    86   wsdStatInit;

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

    88     return SQLITE_MISUSE;

    89   }

    90   *pCurrent = wsdStat.nowValue[op];

    91   *pHighwater = wsdStat.mxValue[op];

    92   if( resetFlag ){

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

    94   }

    95   return SQLITE_OK;

    96 }

    97 

    98 /*

    99 ** Query status information for a single database connection

   100 */

   101 SQLITE_EXPORT int sqlite3_db_status(

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

   103   int op,               /* Status verb */

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

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

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

   107 ){

   108   switch( op ){

   109     case SQLITE_DBSTATUS_LOOKASIDE_USED: {

   110       *pCurrent = db->lookaside.nOut;

   111       *pHighwater = db->lookaside.mxOut;

   112       if( resetFlag ){

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

   114       }

   115       break;

   116     }

   117     default: {

   118       return SQLITE_ERROR;

   119     }

   120   }

   121   return SQLITE_OK;

   122 }