**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.142 2003/09/06 22:18:08 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** A pointer to this structure is used to communicate information
................................................................................
  sqlite *db,
  int (*xBusy)(void*,const char*,int),
  void *pArg
){
  db->xBusyCallback = xBusy;
  db->pBusyArg = pArg;
}


























/*
** This routine installs a default busy handler that waits for the
** specified number of milliseconds before returning 0.
*/
void sqlite_busy_timeout(sqlite *db, int ms){
  if( ms>0 ){

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.143 2003/10/18 09:37:26 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** A pointer to this structure is used to communicate information
................................................................................
  sqlite *db,
  int (*xBusy)(void*,const char*,int),
  void *pArg
){
  db->xBusyCallback = xBusy;
  db->pBusyArg = pArg;
}

#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
/*
** This routine sets the progress callback for an Sqlite database to the
** given callback function with the given argument. The progress callback will
** be invoked every nOps opcodes.
*/
void sqlite_progress_handler(
  sqlite *db, 
  int nOps,
  int (*xProgress)(void*), 
  void *pArg
){
  if( nOps>0 ){
    db->xProgress = xProgress;
    db->nProgressOps = nOps;
    db->pProgressArg = pArg;
  }else{
    db->xProgress = 0;
    db->nProgressOps = 0;
    db->pProgressArg = 0;
  }
}
#endif


/*
** This routine installs a default busy handler that waits for the
** specified number of milliseconds before returning 0.
*/
void sqlite_busy_timeout(sqlite *db, int ms){
  if( ms>0 ){

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.
**
** @(#) $Id: sqlite.h.in,v 1.52 2003/09/06 22:18:08 drh Exp $
*/
#ifndef _SQLITE_H_
#define _SQLITE_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
** This routine can only be called immediately after sqlite_compile()
** or sqlite_reset() and before any calls to sqlite_step().
**
******* THIS IS AN EXPERIMENTAL API AND IS SUBJECT TO CHANGE ******
*/
int sqlite_bind(sqlite_vm*, int idx, const char *value, int len, int copy);




























#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif

#endif /* _SQLITE_H_ */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.
**
** @(#) $Id: sqlite.h.in,v 1.53 2003/10/18 09:37:26 danielk1977 Exp $
*/
#ifndef _SQLITE_H_
#define _SQLITE_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
** This routine can only be called immediately after sqlite_compile()
** or sqlite_reset() and before any calls to sqlite_step().
**
******* THIS IS AN EXPERIMENTAL API AND IS SUBJECT TO CHANGE ******
*/
int sqlite_bind(sqlite_vm*, int idx, const char *value, int len, int copy);

/*
** This routine configures a callback function - the progress callback - that
** is invoked periodically during long running calls to sqlite_exec(),
** sqlite_step() and sqlite_get_table(). An example use for this API is to keep
** a GUI updated during a large query.
**
** The progress callback is invoked once for every N virtual machine opcodes,
** where N is the second argument to this function. The progress callback
** itself is identified by the third argument to this function. The fourth
** argument to this function is a void pointer passed to the progress callback
** function each time it is invoked.
**
** If a call to sqlite_exec(), sqlite_step() or sqlite_get_table() results 
** in less than N opcodes being executed, then the progress callback is not
** invoked.
** 
** Calling this routine overwrites any previously installed progress callback.
** To remove the progress callback altogether, pass NULL as the third
** argument to this function.
**
** If the progress callback returns a result other than 0, then the current 
** query is immediately terminated and any database changes rolled back. If the
** query was part of a larger transaction, then the transaction is not rolled
** back and remains active. The sqlite_exec() call returns SQLITE_ABORT. 
*/
void sqlite_progress_handler(sqlite*, int, int(*)(void*), void*);

#ifdef __cplusplus
}  /* End of the 'extern "C"' block */
#endif

#endif /* _SQLITE_H_ */

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.199 2003/09/27 13:39:39 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
................................................................................
** features of the library and thus keep the size of the library to
** a minimum.
*/
/* #define SQLITE_OMIT_AUTHORIZATION  1 */
/* #define SQLITE_OMIT_INMEMORYDB     1 */
/* #define SQLITE_OMIT_VACUUM         1 */
/* #define SQLITE_OMIT_TIMEDATE_FUNCS 1 */


/*
** Integers of known sizes.  These typedefs might change for architectures
** where the sizes very.  Preprocessor macros are available so that the
** types can be conveniently redefined at compile-type.  Like this:
**
**         cc '-DUINTPTR_TYPE=long long int' ...
................................................................................
  void (*xTrace)(void*,const char*);     /* Trace function */
  void *pTraceArg;                       /* Argument to the trace function */
#ifndef SQLITE_OMIT_AUTHORIZATION
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
                                /* Access authorization function */
  void *pAuthArg;               /* 1st argument to the access auth function */
#endif





};

/*
** Possible values for the sqlite.flags and or Db.flags fields.
**
** On sqlite.flags, the SQLITE_InTrans value means that we have
** executed a BEGIN.  On Db.flags, SQLITE_InTrans means a statement

**    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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.200 2003/10/18 09:37:26 danielk1977 Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
................................................................................
** features of the library and thus keep the size of the library to
** a minimum.
*/
/* #define SQLITE_OMIT_AUTHORIZATION  1 */
/* #define SQLITE_OMIT_INMEMORYDB     1 */
/* #define SQLITE_OMIT_VACUUM         1 */
/* #define SQLITE_OMIT_TIMEDATE_FUNCS 1 */
/* #define SQLITE_OMIT_PROGRESS_CALLBACK 1 */

/*
** Integers of known sizes.  These typedefs might change for architectures
** where the sizes very.  Preprocessor macros are available so that the
** types can be conveniently redefined at compile-type.  Like this:
**
**         cc '-DUINTPTR_TYPE=long long int' ...
................................................................................
  void (*xTrace)(void*,const char*);     /* Trace function */
  void *pTraceArg;                       /* Argument to the trace function */
#ifndef SQLITE_OMIT_AUTHORIZATION
  int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);
                                /* Access authorization function */
  void *pAuthArg;               /* 1st argument to the access auth function */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int (*xProgress)(void *);     /* The progress callback */
  void *pProgressArg;           /* Argument to the progress callback */
  int nProgressOps;             /* Number of opcodes for progress callback */
#endif
};

/*
** Possible values for the sqlite.flags and or Db.flags fields.
**
** On sqlite.flags, the SQLITE_InTrans value means that we have
** executed a BEGIN.  On Db.flags, SQLITE_InTrans means a statement

**    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.
**
*************************************************************************
** A TCL Interface to SQLite
**
** $Id: tclsqlite.c,v 1.50 2003/08/19 14:31:02 drh Exp $
*/
#ifndef NO_TCL     /* Omit this whole file if TCL is unavailable */

#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
*/
typedef struct SqliteDb SqliteDb;
struct SqliteDb {
  sqlite *db;           /* The "real" database structure */
  Tcl_Interp *interp;   /* The interpreter used for this database */
  char *zBusy;          /* The busy callback routine */
  char *zTrace;         /* The trace callback routine */

  char *zAuth;          /* The authorization callback routine */
  SqlFunc *pFunc;       /* List of SQL functions */
  int rc;               /* Return code of most recent sqlite_exec() */
};

/*
** An instance of this structure passes information thru the sqlite
................................................................................
  rc = Tcl_Eval(pDb->interp, zCmd);
  Tcl_DStringFree(&cmd);
  if( rc!=TCL_OK || atoi(Tcl_GetStringResult(pDb->interp)) ){
    return 0;
  }
  return 1;
}
















/*
** This routine is called by the SQLite trace handler whenever a new
** block of SQL is executed.  The TCL script in pDb->zTrace is executed.
*/
static void DbTraceHandler(void *cd, const char *zSql){
  SqliteDb *pDb = (SqliteDb*)cd;
................................................................................
  SqliteDb *pDb = (SqliteDb*)cd;
  int choice;
  static const char *DB_strs[] = {
    "authorizer",         "busy",              "changes",
    "close",              "complete",          "errorcode",
    "eval",               "function",          "last_insert_rowid",
    "onecolumn",          "timeout",            "trace",
    0
  };
  enum DB_enum {
    DB_AUTHORIZER,        DB_BUSY,             DB_CHANGES,
    DB_CLOSE,             DB_COMPLETE,         DB_ERRORCODE,
    DB_EVAL,              DB_FUNCTION,         DB_LAST_INSERT_ROWID,
    DB_ONECOLUMN,         DB_TIMEOUT,          DB_TRACE,            

  };

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
    return TCL_ERROR;
  }
  if( Tcl_GetIndexFromObj(interp, objv[1], DB_strs, "option", 0, &choice) ){
................................................................................
        sqlite_busy_handler(pDb->db, DbBusyHandler, pDb);
      }else{
        sqlite_busy_handler(pDb->db, 0, 0);
      }
    }
    break;
  }











































  /*
  **     $db changes
  **
  ** Return the number of rows that were modified, inserted, or deleted by
  ** the most recent "eval".
  */

**    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.
**
*************************************************************************
** A TCL Interface to SQLite
**
** $Id: tclsqlite.c,v 1.51 2003/10/18 09:37:26 danielk1977 Exp $
*/
#ifndef NO_TCL     /* Omit this whole file if TCL is unavailable */

#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
*/
typedef struct SqliteDb SqliteDb;
struct SqliteDb {
  sqlite *db;           /* The "real" database structure */
  Tcl_Interp *interp;   /* The interpreter used for this database */
  char *zBusy;          /* The busy callback routine */
  char *zTrace;         /* The trace callback routine */
  char *zProgress;      /* The progress callback routine */
  char *zAuth;          /* The authorization callback routine */
  SqlFunc *pFunc;       /* List of SQL functions */
  int rc;               /* Return code of most recent sqlite_exec() */
};

/*
** An instance of this structure passes information thru the sqlite
................................................................................
  rc = Tcl_Eval(pDb->interp, zCmd);
  Tcl_DStringFree(&cmd);
  if( rc!=TCL_OK || atoi(Tcl_GetStringResult(pDb->interp)) ){
    return 0;
  }
  return 1;
}

/*
** This routine is invoked as the 'progress callback' for the database.
*/
static int DbProgressHandler(void *cd){
  SqliteDb *pDb = (SqliteDb*)cd;
  int rc;

  assert( pDb->zProgress );
  rc = Tcl_Eval(pDb->interp, pDb->zProgress);
  if( rc!=TCL_OK || atoi(Tcl_GetStringResult(pDb->interp)) ){
    return 1;
  }
  return 0;
}

/*
** This routine is called by the SQLite trace handler whenever a new
** block of SQL is executed.  The TCL script in pDb->zTrace is executed.
*/
static void DbTraceHandler(void *cd, const char *zSql){
  SqliteDb *pDb = (SqliteDb*)cd;
................................................................................
  SqliteDb *pDb = (SqliteDb*)cd;
  int choice;
  static const char *DB_strs[] = {
    "authorizer",         "busy",              "changes",
    "close",              "complete",          "errorcode",
    "eval",               "function",          "last_insert_rowid",
    "onecolumn",          "timeout",            "trace",
    "progress",           0
  };
  enum DB_enum {
    DB_AUTHORIZER,        DB_BUSY,             DB_CHANGES,
    DB_CLOSE,             DB_COMPLETE,         DB_ERRORCODE,
    DB_EVAL,              DB_FUNCTION,         DB_LAST_INSERT_ROWID,
    DB_ONECOLUMN,         DB_TIMEOUT,          DB_TRACE,            
    DB_PROGRESS,
  };

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
    return TCL_ERROR;
  }
  if( Tcl_GetIndexFromObj(interp, objv[1], DB_strs, "option", 0, &choice) ){
................................................................................
        sqlite_busy_handler(pDb->db, DbBusyHandler, pDb);
      }else{
        sqlite_busy_handler(pDb->db, 0, 0);
      }
    }
    break;
  }

  /*    $db progress ?N CALLBACK?
  ** 
  ** Invoke the given callback every N virtual machine opcodes while executing
  ** queries.
  */
  case DB_PROGRESS: {
    if( objc==2 ){
      if( pDb->zProgress ){
        Tcl_AppendResult(interp, pDb->zProgress, 0);
      }
    }else if( objc==4 ){
      char *zProgress;
      int len;
      int N;
      if( TCL_OK!=Tcl_GetIntFromObj(interp, objv[2], &N) ){
	return TCL_ERROR;
      };
      if( pDb->zProgress ){
        Tcl_Free(pDb->zProgress);
      }
      zProgress = Tcl_GetStringFromObj(objv[3], &len);
      if( zProgress && len>0 ){
        pDb->zProgress = Tcl_Alloc( len + 1 );
        strcpy(pDb->zProgress, zProgress);
      }else{
        pDb->zProgress = 0;
      }
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
      if( pDb->zProgress ){
        pDb->interp = interp;
        sqlite_progress_handler(pDb->db, N, DbProgressHandler, pDb);
      }else{
        sqlite_progress_handler(pDb->db, 0, 0, 0);
      }
#endif
    }else{
      Tcl_WrongNumArgs(interp, 2, objv, "N CALLBACK");
      return TCL_ERROR;
    }
    break;
  }

  /*
  **     $db changes
  **
  ** Return the number of rows that were modified, inserted, or deleted by
  ** the most recent "eval".
  */

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.241 2003/09/27 00:56:32 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
  char **zStack = p->zStack; /* Text stack */
  Stack *aStack = p->aStack; /* Additional stack information */
  char zBuf[100];            /* Space to sprintf() an integer */
#ifdef VDBE_PROFILE
  unsigned long long start;  /* CPU clock count at start of opcode */
  int origPc;                /* Program counter at start of opcode */
#endif




  if( p->magic!=VDBE_MAGIC_RUN ) return SQLITE_MISUSE;
  assert( db->magic==SQLITE_MAGIC_BUSY );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  if( sqlite_malloc_failed ) goto no_mem;
................................................................................
    /* Only allow tracing if NDEBUG is not defined.
    */
#ifndef NDEBUG
    if( p->trace ){
      sqliteVdbePrintOp(p->trace, pc, pOp);
    }
#endif


















    switch( pOp->opcode ){

/*****************************************************************************
** What follows is a massive switch statement where each case implements a
** separate instruction in the virtual machine.  If we follow the usual
** indentation conventions, each case should be indented by 6 spaces.  But

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.242 2003/10/18 09:37:26 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
  char **zStack = p->zStack; /* Text stack */
  Stack *aStack = p->aStack; /* Additional stack information */
  char zBuf[100];            /* Space to sprintf() an integer */
#ifdef VDBE_PROFILE
  unsigned long long start;  /* CPU clock count at start of opcode */
  int origPc;                /* Program counter at start of opcode */
#endif
#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
  int nProgressOps = 0;      /* Opcodes executed since progress callback. */
#endif

  if( p->magic!=VDBE_MAGIC_RUN ) return SQLITE_MISUSE;
  assert( db->magic==SQLITE_MAGIC_BUSY );
  assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY );
  p->rc = SQLITE_OK;
  assert( p->explain==0 );
  if( sqlite_malloc_failed ) goto no_mem;
................................................................................
    /* Only allow tracing if NDEBUG is not defined.
    */
#ifndef NDEBUG
    if( p->trace ){
      sqliteVdbePrintOp(p->trace, pc, pOp);
    }
#endif

#ifndef SQLITE_OMIT_PROGRESS_CALLBACK
    /* Call the progress callback if it is configured and the required number
    ** of VDBE ops have been executed (either since this invocation of
    ** sqliteVdbeExec() or since last time the progress callback was called).
    ** If the progress callback returns non-zero, exit the virtual machine with
    ** a return code SQLITE_ABORT.
    */
    if( db->xProgress && (db->nProgressOps==nProgressOps) ){
      if( db->xProgress(db->pProgressArg)!=0 ){
        rc = SQLITE_ABORT;
        continue; /* skip to the next iteration of the for loop */
      }
      nProgressOps = 0;
    }
    nProgressOps++;
#endif

    switch( pOp->opcode ){

/*****************************************************************************
** What follows is a massive switch statement where each case implements a
** separate instruction in the virtual machine.  If we follow the usual
** indentation conventions, each case should be indented by 6 spaces.  But

# 2001 September 15
#
# 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 file implements regression tests for SQLite library.  The
# focus of this file is testing the 'progress callback'.
#
# $Id: progress.test,v 1.1 2003/10/18 09:37:27 danielk1977 Exp $

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

# Build some test data
#
execsql {
  BEGIN;
  CREATE TABLE t1(a);
  INSERT INTO t1 VALUES(1);
  INSERT INTO t1 VALUES(2);
  INSERT INTO t1 VALUES(3);
  INSERT INTO t1 VALUES(4);
  INSERT INTO t1 VALUES(5);
  INSERT INTO t1 VALUES(6);
  INSERT INTO t1 VALUES(7);
  INSERT INTO t1 VALUES(8);
  INSERT INTO t1 VALUES(9);
  INSERT INTO t1 VALUES(10);
  COMMIT;
}


# Test that the progress callback is invoked.
do_test progress-1.0 {
  set counter 0
  db progress 1 "[namespace code {incr counter}] ; expr 0"
  execsql {
    SELECT * FROM t1
  }
  expr $counter > 1
} 1

# Test that the query is abandoned when the progress callback returns non-zero
do_test progress1.1 {
  set counter 0
  db progress 1 "[namespace code {incr counter}] ; expr 1"
  execsql {
    SELECT * FROM t1
  }
  set counter 
} 1

# Test that the query is rolled back when the progress callback returns
# non-zero.
do_test progress1.2 {

  # This figures out how many opcodes it takes to copy 5 extra rows into t1.
  db progress 1 "[namespace code {incr five_rows}] ; expr 0"
  set five_rows 0
  execsql {
    INSERT INTO t1 SELECT a+10 FROM t1 WHERE a < 6
  }
  db progress 0 ""
  execsql {
    DELETE FROM t1 WHERE a > 10
  }

  # Now set up the progress callback to abandon the query after the number of
  # opcodes to copy 5 rows. That way, when we try to copy 6 rows, we know
  # some data will have been inserted into the table by the time the progress
  # callback abandons the query.
  db progress $five_rows "expr 1"
  execsql {
    INSERT INTO t1 SELECT a+10 FROM t1 WHERE a < 7
  }
  execsql {
    SELECT count(*) FROM t1
  }
} 10

# Test that an active transaction remains active and not rolled back after the
# progress query abandons a query. 
do_test progress1.3 {

  db progress 0 ""
  execsql BEGIN
  execsql {
    INSERT INTO t1 VALUES(11)
  }
  db progress 1 "expr 1"
  execsql {
    INSERT INTO t1 VALUES(12)
  }
  db progress 0 ""
  execsql COMMIT
  execsql {
    SELECT count(*) FROM t1
  }
} 11

# Check that a value of 0 for N means no progress callback
do_test progress1.4 {
  set counter 0
  db progress 0 "[namespace code {incr counter}] ; expr 0"
  execsql {
    SELECT * FROM t1;
  }
  set counter
} 0

db progress 0 ""

finish_test

#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: c_interface.tcl,v 1.38 2003/07/08 23:42:25 drh Exp $}

puts {<html>
<head>
  <title>The C language interface to the SQLite library</title>
</head>
<body bgcolor=white>
<h1 align=center>
................................................................................

char *sqlite_mprintf(const char *zFormat, ...);

char *sqlite_vmprintf(const char *zFormat, va_list);

void sqlite_freemem(char*);



</pre></blockquote>

<p>All of the above definitions are included in the "sqlite.h"
header file that comes in the source tree.</p>

<h3>3.1 The ROWID of the most recent insert</h3>

................................................................................
<b>sprintf()</b> except that it writes its results into memory obtained
from malloc() and returns a pointer to the malloced buffer.  
<b>sqlite_mprintf()</b> also understands the %q and %Q extensions described
above.  The <b>sqlite_vmprintf()</b> is a varargs version of the same
routine.  The string pointer that these routines return should be freed
by passing it to <b>sqlite_freemem()</b>.
</p>

























<a name="cfunc">
<h2>4.0 Adding New SQL Functions</h2>

<p>Beginning with version 2.4.0, SQLite allows the SQL language to be
extended with new functions implemented as C code.  The following interface
is used:

#
# Run this Tcl script to generate the sqlite.html file.
#
set rcsid {$Id: c_interface.tcl,v 1.39 2003/10/18 09:37:27 danielk1977 Exp $}

puts {<html>
<head>
  <title>The C language interface to the SQLite library</title>
</head>
<body bgcolor=white>
<h1 align=center>
................................................................................

char *sqlite_mprintf(const char *zFormat, ...);

char *sqlite_vmprintf(const char *zFormat, va_list);

void sqlite_freemem(char*);

void sqlite_progress_handler(sqlite*, int, int (*)(void*), void*);

</pre></blockquote>

<p>All of the above definitions are included in the "sqlite.h"
header file that comes in the source tree.</p>

<h3>3.1 The ROWID of the most recent insert</h3>

................................................................................
<b>sprintf()</b> except that it writes its results into memory obtained
from malloc() and returns a pointer to the malloced buffer.  
<b>sqlite_mprintf()</b> also understands the %q and %Q extensions described
above.  The <b>sqlite_vmprintf()</b> is a varargs version of the same
routine.  The string pointer that these routines return should be freed
by passing it to <b>sqlite_freemem()</b>.
</p>

<h3>3.10 Performing background jobs during large queries </h2>

<p>The <b>sqlite_progress_handler()</b> routine can be used to register a
callback routine with an SQLite database to be invoked periodically during long
running calls to <b>sqlite_exec()</b>, <b>sqlite_step()</b> and the various
wrapper functions.
</p>

<p>The callback is invoked every N virtual machine operations, where N is
supplied as the second argument to <b>sqlite_progress_handler()</b>. The third
and fourth arguments to <b>sqlite_progress_handler()</b> are a pointer to the
routine to be invoked and a void pointer to be passed as the first argument to
it.
</p>

<p>The time taken to execute each virtual machine operation can vary based on
many factors.  A typical value for a 1 GHz PC is between half and three million
per second but may be much higher or lower, depending on the query.  As such it
is difficult to schedule background operations based on virtual machine
operations. Instead, it is recommended that a callback be scheduled relatively
frequently (say every 1000 instructions) and external timer routines used to
determine whether or not background jobs need to be run.  
</p>

<a name="cfunc">
<h2>4.0 Adding New SQL Functions</h2>

<p>Beginning with version 2.4.0, SQLite allows the SQL language to be
extended with new functions implemented as C code.  The following interface
is used: