# 2016 August 23
#
# 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.
#

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
} 
source $testdir/tester.tcl
ifcapable !session {finish_test; return}

set testprefix changebatch1


proc sql_to_changeset {method sql} {
  sqlite3session S db main
  S attach *
  execsql $sql
  set ret [S $method]
  S delete
  return $ret
}

proc do_changebatch_test {tn method args} {
  set C [list]
  foreach a $args {
    lappend C [sql_to_changeset $method $a]
  }

  sqlite3changebatch cb db
  set i 1
  foreach ::cs [lrange $C 0 end-1] {
    set rc [cb add $::cs]
    if {$rc!="SQLITE_OK"} { error "expected SQLITE_OK, got $rc (i=$i)" }
    incr i
  }

  set ::cs [lindex $C end]
  do_test $tn { cb add [set ::cs] } SQLITE_CONSTRAINT
  cb delete
}

proc do_changebatch_test1 {tn args} {
  uplevel do_changebatch_test $tn changeset $args
}
proc do_changebatch_test2 {tn args} {
  uplevel do_changebatch_test $tn fullchangeset $args
}

#-------------------------------------------------------------------------
# The body of the following loop contains tests for database schemas
# that do not feature multi-column UNIQUE constraints. In this case
# it doesn't matter if the changesets are generated using
# sqlite3session_changeset() or sqlite3session_fullchangeset().
#
foreach {tn testfunction} {
  1 do_changebatch_test1
  2 do_changebatch_test2
} {
  reset_db

  #-------------------------------------------------------------------------
  #
  do_execsql_test $tn.1.0 {
    CREATE TABLE t1(a PRIMARY KEY, b);
  }
  
  $testfunction $tn.1.1 {
    INSERT INTO t1 VALUES(1, 1);
  } {
    DELETE FROM t1 WHERE a=1;
  }
  
  do_execsql_test $tn.1.2.0 {
    INSERT INTO t1 VALUES(1, 1);
    INSERT INTO t1 VALUES(2, 2);
    INSERT INTO t1 VALUES(3, 3);
  }
  $testfunction $tn.1.2.1 {
    DELETE FROM t1 WHERE a=2;
  } {
    INSERT INTO t1 VALUES(2, 2);
  }
  
  #-------------------------------------------------------------------------
  #
  do_execsql_test $tn.2.0 {
    CREATE TABLE x1(a, b PRIMARY KEY, c UNIQUE);
    CREATE TABLE x2(a PRIMARY KEY, b UNIQUE, c UNIQUE);
    CREATE INDEX x1a ON x1(a);
  
    INSERT INTO x1 VALUES(1, 1, 'a');
    INSERT INTO x1 VALUES(1, 2, 'b');
    INSERT INTO x1 VALUES(1, 3, 'c');
  }
  
  $testfunction $tn.2.1 {
    DELETE FROM x1 WHERE b=2;
  } {
    UPDATE x1 SET c='b' WHERE b=3;
  }
  
  $testfunction $tn.2.2 {
    DELETE FROM x1 WHERE b=1;
  } {
    INSERT INTO x1 VALUES(1, 5, 'a');
  }

  set L [list]
  for {set i 1000} {$i < 10000} {incr i} {
    lappend L "INSERT INTO x2 VALUES($i, $i, 'x' || $i)"
  }
  lappend L "DELETE FROM x2 WHERE b=1005"
  $testfunction $tn.2.3 {*}$L

  execsql { INSERT INTO x1 VALUES('f', 'f', 'f') }
  $testfunction $tn.2.4 {
    INSERT INTO x2 VALUES('f', 'f', 'f');
  } {
    INSERT INTO x1 VALUES('g', 'g', 'g');
  } {
    DELETE FROM x1 WHERE b='f';
  } {
    INSERT INTO x2 VALUES('g', 'g', 'g');
  } {
    INSERT INTO x1 VALUES('f', 'f', 'f');
  }

  execsql {
    DELETE FROM x1;
    INSERT INTO x1 VALUES(1.5, 1.5, 1.5);
  }
  $testfunction $tn.2.5 {
    DELETE FROM x1 WHERE b BETWEEN 1 AND 2;
  } {
    INSERT INTO x1 VALUES(2.5, 2.5, 2.5);
  } {
    INSERT INTO x1 VALUES(1.5, 1.5, 1.5);
  }

  execsql {
    DELETE FROM x2;
    INSERT INTO x2 VALUES(X'abcd', X'1234', X'7890');
    INSERT INTO x2 VALUES(X'0000', X'0000', X'0000');
  }
  breakpoint
  $testfunction $tn.2.6 {
    UPDATE x2 SET c = X'1234' WHERE a=X'abcd';
    INSERT INTO x2 VALUES(X'1234', X'abcd', X'7890');
  } {
    DELETE FROM x2 WHERE b=X'0000';
  } {
    INSERT INTO x2 VALUES(1, X'0000', NULL);
  }
}

#-------------------------------------------------------------------------
# Test some multi-column UNIQUE constraints. First Using _changeset() to
# demonstrate the problem, then using _fullchangeset() to show that it has
# been fixed.
#
reset_db
do_execsql_test 3.0 {
  CREATE TABLE y1(a PRIMARY KEY, b, c, UNIQUE(b, c));
  INSERT INTO y1 VALUES(1, 1, 1);
  INSERT INTO y1 VALUES(2, 2, 2);
  INSERT INTO y1 VALUES(3, 3, 3);
  INSERT INTO y1 VALUES(4, 3, 4);
  BEGIN;
}

do_test 3.1.1 {
  set c1 [sql_to_changeset changeset { DELETE FROM y1 WHERE a=4    }]
  set c2 [sql_to_changeset changeset { UPDATE y1 SET c=4 WHERE a=3 }]
  sqlite3changebatch cb db
  cb add $c1
  cb add $c2
} {SQLITE_OK}
do_test 3.1.2 {
  cb delete
  execsql ROLLBACK
} {}

do_test 3.1.1 {
  set c1 [sql_to_changeset fullchangeset { DELETE FROM y1 WHERE a=4    }]
  set c2 [sql_to_changeset fullchangeset { UPDATE y1 SET c=4 WHERE a=3 }]
  sqlite3changebatch cb db
  cb add $c1
  cb add $c2
} {SQLITE_CONSTRAINT}
do_test 3.1.2 {
  cb delete
} {}

#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 4.0 {
  CREATE TABLE t1(x, y, z, PRIMARY KEY(x, y), UNIQUE(z));
}

do_test 4.1 {
  set c1 [sql_to_changeset fullchangeset { INSERT INTO t1 VALUES(1, 2, 3) }]
  execsql {
    DROP TABLE t1;
    CREATE TABLE t1(w, x, y, z, PRIMARY KEY(x, y), UNIQUE(z));
  }
  sqlite3changebatch cb db
  list [catch { cb add $c1 } msg] $msg
} {1 SQLITE_RANGE}



finish_test

# 2011 Mar 21
#
# 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.
#
#***********************************************************************
#
# The focus of this file is testing the session module.
#

if {![info exists testdir]} {
  set testdir [file join [file dirname [info script]] .. .. test]
} 
source [file join [file dirname [info script]] session_common.tcl]
source $testdir/tester.tcl
ifcapable !session {finish_test; return}
set testprefix changebatchfault

do_execsql_test 1.0 {
  CREATE TABLE t1(a, b, c PRIMARY KEY, UNIQUE(a, b));
  INSERT INTO t1 VALUES('a', 'a', 'a');
  INSERT INTO t1 VALUES('b', 'b', 'b');
}

set ::c1 [changeset_from_sql { delete from t1 where c='a' }]
set ::c2 [changeset_from_sql { insert into t1 values('c', 'c', 'c') }]

do_faultsim_test 1 -faults oom-* -body {
  sqlite3changebatch cb db
  cb add $::c1
  cb add $::c2
} -test {
  faultsim_test_result {0 SQLITE_OK} {1 SQLITE_NOMEM}
  catch { cb delete }
}


finish_test

#if !defined(SQLITE_TEST) || (defined(SQLITE_ENABLE_SESSION) && defined(SQLITE_ENABLE_PREUPDATE_HOOK))

#include "sqlite3session.h"
#include "sqlite3changebatch.h"

#include <assert.h>
#include <string.h>

typedef struct BatchTable BatchTable;
typedef struct BatchIndex BatchIndex;
typedef struct BatchIndexEntry BatchIndexEntry;
typedef struct BatchHash BatchHash;

struct sqlite3_changebatch {
  sqlite3 *db;                    /* Database handle used to read schema */
  BatchTable *pTab;               /* First in linked list of tables */
  int iChangesetId;               /* Current changeset id */
  int iNextIdxId;                 /* Next available index id */
  int nEntry;                     /* Number of entries in hash table */
  int nHash;                      /* Number of hash buckets */
  BatchIndexEntry **apHash;       /* Array of hash buckets */
};

struct BatchTable {
  BatchIndex *pIdx;               /* First in linked list of UNIQUE indexes */
  BatchTable *pNext;              /* Next table */
  char zTab[1];                   /* Table name */
};

struct BatchIndex {
  BatchIndex *pNext;              /* Next index on same table */
  int iId;                        /* Index id (assigned internally) */
  int bPk;                        /* True for PK index */
  int nCol;                       /* Size of aiCol[] array */
  int *aiCol;                     /* Array of columns that make up index */
};

struct BatchIndexEntry {
  BatchIndexEntry *pNext;         /* Next colliding hash table entry */
  int iChangesetId;               /* Id of associated changeset */
  int iIdxId;                     /* Id of index this key is from */
  int szRecord;
  char aRecord[1];
};

/*
** Allocate and zero a block of nByte bytes. Must be freed using cbFree().
*/
static void *cbMalloc(int *pRc, int nByte){
  void *pRet;

  if( *pRc ){
    pRet = 0;
  }else{
    pRet = sqlite3_malloc(nByte);
    if( pRet ){
      memset(pRet, 0, nByte);
    }else{
      *pRc = SQLITE_NOMEM;
    }
  }

  return pRet;
}

/*
** Free an allocation made by cbMalloc().
*/
static void cbFree(void *p){
  sqlite3_free(p);
}

/*
** Return the hash bucket that pEntry belongs in.
*/
static int cbHash(sqlite3_changebatch *p, BatchIndexEntry *pEntry){
  unsigned int iHash = (unsigned int)pEntry->iIdxId;
  unsigned char *pEnd = (unsigned char*)&pEntry->aRecord[pEntry->szRecord];
  unsigned char *pIter;

  for(pIter=(unsigned char*)pEntry->aRecord; pIter<pEnd; pIter++){
    iHash += (iHash << 7) + *pIter;
  }

  return (int)(iHash % p->nHash);
}

/*
** Resize the hash table.
*/
static int cbHashResize(sqlite3_changebatch *p){
  int rc = SQLITE_OK;
  BatchIndexEntry **apNew;
  int nNew = (p->nHash ? p->nHash*2 : 512);
  int i;

  apNew = cbMalloc(&rc, sizeof(BatchIndexEntry*) * nNew);
  if( rc==SQLITE_OK ){
    int nHash = p->nHash;
    p->nHash = nNew;
    for(i=0; i<nHash; i++){
      BatchIndexEntry *pEntry;
      while( (pEntry=p->apHash[i])!=0 ){
        int iHash = cbHash(p, pEntry);
        p->apHash[i] = pEntry->pNext;
        pEntry->pNext = apNew[iHash];
        apNew[iHash] = pEntry;
      }
    }

    cbFree(p->apHash);
    p->apHash = apNew;
  }

  return rc;
}


/*
** Allocate a new sqlite3_changebatch object.
*/
int sqlite3changebatch_new(sqlite3 *db, sqlite3_changebatch **pp){
  sqlite3_changebatch *pRet;
  int rc = SQLITE_OK;
  *pp = pRet = (sqlite3_changebatch*)cbMalloc(&rc, sizeof(sqlite3_changebatch));
  if( pRet ){
    pRet->db = db;
  }
  return rc;
}

/*
** Add a BatchIndex entry for index zIdx to table pTab.
*/
static int cbAddIndex(
  sqlite3_changebatch *p, 
  BatchTable *pTab, 
  const char *zIdx, 
  int bPk
){
  int nCol = 0;
  sqlite3_stmt *pIndexInfo = 0;
  BatchIndex *pNew = 0;
  int rc;
  char *zIndexInfo;

  zIndexInfo = (char*)sqlite3_mprintf("PRAGMA main.index_info = %Q", zIdx);
  if( zIndexInfo ){
    rc = sqlite3_prepare_v2(p->db, zIndexInfo, -1, &pIndexInfo, 0);
    sqlite3_free(zIndexInfo);
  }else{
    rc = SQLITE_NOMEM;
  }

  if( rc==SQLITE_OK ){
    while( SQLITE_ROW==sqlite3_step(pIndexInfo) ){ nCol++; }
    rc = sqlite3_reset(pIndexInfo);
  }

  pNew = (BatchIndex*)cbMalloc(&rc, sizeof(BatchIndex) + sizeof(int) * nCol);
  if( rc==SQLITE_OK ){
    int rc2;
    pNew->nCol = nCol;
    pNew->bPk = bPk;
    pNew->aiCol = (int*)&pNew[1];
    pNew->iId = p->iNextIdxId++;
    while( SQLITE_ROW==sqlite3_step(pIndexInfo) ){ 
      int i = sqlite3_column_int(pIndexInfo, 0);
      int j = sqlite3_column_int(pIndexInfo, 1);
      pNew->aiCol[i] = j;
    }
    rc = sqlite3_reset(pIndexInfo);
  }

  if( rc==SQLITE_OK ){
    pNew->pNext = pTab->pIdx;
    pTab->pIdx = pNew;
  }else{
    cbFree(pNew);
  }
  sqlite3_finalize(pIndexInfo);

  return rc;
}

/*
** Free the object passed as the first argument.
*/
static void cbFreeTable(BatchTable *pTab){
  BatchIndex *pIdx;
  BatchIndex *pIdxNext;
  for(pIdx=pTab->pIdx; pIdx; pIdx=pIdxNext){
    pIdxNext = pIdx->pNext;
    cbFree(pIdx);
  }
  cbFree(pTab);
}

/*
** Find or create the BatchTable object named zTab.
*/
static int cbFindTable(
  sqlite3_changebatch *p, 
  const char *zTab, 
  BatchTable **ppTab
){
  BatchTable *pRet = 0;
  int rc = SQLITE_OK;

  for(pRet=p->pTab; pRet; pRet=pRet->pNext){
    if( 0==sqlite3_stricmp(zTab, pRet->zTab) ) break;
  }

  if( pRet==0 ){
    int nTab = strlen(zTab);
    pRet = (BatchTable*)cbMalloc(&rc, nTab + sizeof(BatchTable));
    if( pRet ){
      sqlite3_stmt *pIndexList = 0;
      char *zIndexList = 0;
      int rc2;
      memcpy(pRet->zTab, zTab, nTab);

      zIndexList = sqlite3_mprintf("PRAGMA main.index_list = %Q", zTab);
      if( zIndexList==0 ){
        rc = SQLITE_NOMEM;
      }else{
        rc = sqlite3_prepare_v2(p->db, zIndexList, -1, &pIndexList, 0);
        sqlite3_free(zIndexList);
      }

      while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pIndexList) ){
        if( sqlite3_column_int(pIndexList, 2) ){
          const char *zIdx = (const char*)sqlite3_column_text(pIndexList, 1);
          const char *zTyp = (const char*)sqlite3_column_text(pIndexList, 3);
          rc = cbAddIndex(p, pRet, zIdx, (zTyp[0]=='p'));
        }
      }
      rc2 = sqlite3_finalize(pIndexList);
      if( rc==SQLITE_OK ) rc = rc2;

      if( rc==SQLITE_OK ){
        pRet->pNext = p->pTab;
        p->pTab = pRet;
      }else{
        cbFreeTable(pRet);
        pRet = 0;
      }
    }
  }

  *ppTab = pRet;
  return rc;
}

/*
** Extract value iVal from the changeset iterator passed as the first
** argument. Set *ppVal to point to the value before returning.
**
** This function attempts to extract the value using function xVal
** (which is always either sqlite3changeset_new or sqlite3changeset_old).
** If the call returns SQLITE_OK but does not supply an sqlite3_value*
** pointer, an attempt to extract the value is made using the xFallback 
** function.
*/
static int cbGetChangesetValue(
  sqlite3_changeset_iter *pIter, 
  int (*xVal)(sqlite3_changeset_iter*,int,sqlite3_value**),
  int (*xFallback)(sqlite3_changeset_iter*,int,sqlite3_value**),
  int iVal,
  sqlite3_value **ppVal
){
  int rc = xVal(pIter, iVal, ppVal);
  if( rc==SQLITE_OK && *ppVal==0 && xFallback ){
    rc = xFallback(pIter, iVal, ppVal);
  }
  return rc;
}

static int cbAddToHash(
  sqlite3_changebatch *p, 
  sqlite3_changeset_iter *pIter, 
  BatchIndex *pIdx, 
  int (*xVal)(sqlite3_changeset_iter*,int,sqlite3_value**),
  int (*xFallback)(sqlite3_changeset_iter*,int,sqlite3_value**),
  int *pbConf
){
  BatchIndexEntry *pNew;
  int sz = pIdx->nCol;
  int i;
  int iOut = 0;
  int rc = SQLITE_OK;

  for(i=0; rc==SQLITE_OK && i<pIdx->nCol; i++){
    sqlite3_value *pVal;
    rc = cbGetChangesetValue(pIter, xVal, xFallback, pIdx->aiCol[i], &pVal);
    if( rc==SQLITE_OK ){
      int eType = 0;
      if( pVal ) eType = sqlite3_value_type(pVal);
      switch( eType ){
        case 0:
        case SQLITE_NULL:
          return SQLITE_OK;

        case SQLITE_INTEGER:
          sz += 8;
          break;
        case SQLITE_FLOAT:
          sz += 8;
          break;

        default:
          assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB );
          sz += sqlite3_value_bytes(pVal);
          break;
      }
    }
  }

  pNew = cbMalloc(&rc, sizeof(BatchIndexEntry) + sz);
  if( pNew ){
    pNew->iChangesetId = p->iChangesetId;
    pNew->iIdxId = pIdx->iId;
    pNew->szRecord = sz;

    for(i=0; i<pIdx->nCol; i++){
      int eType;
      sqlite3_value *pVal;
      rc = cbGetChangesetValue(pIter, xVal, xFallback, pIdx->aiCol[i], &pVal);
      if( rc!=SQLITE_OK ) break;  /* coverage: condition is never true */
      eType = sqlite3_value_type(pVal);
      pNew->aRecord[iOut++] = eType;
      switch( eType ){
        case SQLITE_INTEGER: {
          sqlite3_int64 i64 = sqlite3_value_int64(pVal);
          memcpy(&pNew->aRecord[iOut], &i64, 8);
          iOut += 8;
          break;
        }
        case SQLITE_FLOAT: {
          double d64 = sqlite3_value_double(pVal);
          memcpy(&pNew->aRecord[iOut], &d64, sizeof(double));
          iOut += sizeof(double);
          break;
        }

        default: {
          int nByte = sqlite3_value_bytes(pVal);
          const char *z = (const char*)sqlite3_value_blob(pVal);
          memcpy(&pNew->aRecord[iOut], z, nByte);
          iOut += nByte;
          break;
        }
      }
    }
  }

  if( rc==SQLITE_OK && p->nEntry>=(p->nHash/2) ){
    rc = cbHashResize(p);
  }

  if( rc==SQLITE_OK ){
    BatchIndexEntry *pIter;
    int iHash = cbHash(p, pNew);

    assert( iHash>=0 && iHash<p->nHash );
    for(pIter=p->apHash[iHash]; pIter; pIter=pIter->pNext){
      if( pNew->szRecord==pIter->szRecord 
       && 0==memcmp(pNew->aRecord, pIter->aRecord, pNew->szRecord)
      ){
        if( pNew->iChangesetId!=pIter->iChangesetId ){
          *pbConf = 1;
        }
        cbFree(pNew);
        pNew = 0;
        break;
      }
    }

    if( pNew ){
      pNew->pNext = p->apHash[iHash];
      p->apHash[iHash] = pNew;
      p->nEntry++;
    }
  }else{
    cbFree(pNew);
  }

  return rc;
}


/*
** Add a changeset to the current batch.
*/
int sqlite3changebatch_add(sqlite3_changebatch *p, void *pBuf, int nBuf){
  sqlite3_changeset_iter *pIter;  /* Iterator opened on pBuf/nBuf */
  int rc;                         /* Return code */
  int bConf = 0;                  /* Conflict was detected */

  rc = sqlite3changeset_start(&pIter, nBuf, pBuf);
  if( rc==SQLITE_OK ){
    int rc2;
    for(rc2 = sqlite3changeset_next(pIter);
        rc2==SQLITE_ROW;
        rc2 = sqlite3changeset_next(pIter)
    ){
      BatchTable *pTab;
      BatchIndex *pIdx;
      const char *zTab;           /* Table this change applies to */
      int nCol;                   /* Number of columns in table */
      int op;                     /* UPDATE, INSERT or DELETE */

      sqlite3changeset_op(pIter, &zTab, &nCol, &op, 0);
      assert( op==SQLITE_INSERT || op==SQLITE_UPDATE || op==SQLITE_DELETE );

      rc = cbFindTable(p, zTab, &pTab);
      assert( pTab || rc!=SQLITE_OK );
      if( pTab ){
        for(pIdx=pTab->pIdx; pIdx && rc==SQLITE_OK; pIdx=pIdx->pNext){
          if( op==SQLITE_UPDATE && pIdx->bPk ) continue;
          if( op==SQLITE_UPDATE || op==SQLITE_DELETE ){
            rc = cbAddToHash(p, pIter, pIdx, sqlite3changeset_old, 0, &bConf);
          }
          if( op==SQLITE_UPDATE || op==SQLITE_INSERT ){
            rc = cbAddToHash(p, pIter, pIdx, 
                sqlite3changeset_new, sqlite3changeset_old, &bConf
            );
          }
        }
      }
      if( rc!=SQLITE_OK ) break;
    }

    rc2 = sqlite3changeset_finalize(pIter);
    if( rc==SQLITE_OK ) rc = rc2;
  }

  if( rc==SQLITE_OK && bConf ){
    rc = SQLITE_CONSTRAINT;
  }
  p->iChangesetId++;
  return rc;
}

/*
** Zero an existing changebatch object.
*/
void sqlite3changebatch_zero(sqlite3_changebatch *p){
  int i;
  for(i=0; i<p->nHash; i++){
    BatchIndexEntry *pEntry;
    BatchIndexEntry *pNext;
    for(pEntry=p->apHash[i]; pEntry; pEntry=pNext){
      pNext = pEntry->pNext;
      cbFree(pEntry);
    }
  }
  cbFree(p->apHash);
  p->nHash = 0;
  p->apHash = 0;
}

/*
** Delete a changebatch object.
*/
void sqlite3changebatch_delete(sqlite3_changebatch *p){
  BatchTable *pTab;
  BatchTable *pTabNext;

  sqlite3changebatch_zero(p);
  for(pTab=p->pTab; pTab; pTab=pTabNext){
    pTabNext = pTab->pNext;
    cbFreeTable(pTab);
  }
  cbFree(p);
}

/*
** Return the db handle.
*/
sqlite3 *sqlite3changebatch_db(sqlite3_changebatch *p){
  return p->db;
}

#endif /* SQLITE_ENABLE_SESSION && SQLITE_ENABLE_PREUPDATE_HOOK */

#if !defined(SQLITECHANGEBATCH_H_) 
#define SQLITECHANGEBATCH_H_ 1

typedef struct sqlite3_changebatch sqlite3_changebatch;

/*
** Create a new changebatch object for detecting conflicts between
** changesets associated with a schema equivalent to that of the "main"
** database of the open database handle db passed as the first
** parameter. It is the responsibility of the caller to ensure that
** the database handle is not closed until after the changebatch
** object has been deleted.
**
** A changebatch object is used to detect batches of non-conflicting
** changesets. Changesets that do not conflict may be applied to the 
** target database in any order without affecting the final state of 
** the database.
**
** The changebatch object only works reliably if PRIMARY KEY and UNIQUE
** constraints on tables affected by the changesets use collation
** sequences that are equivalent to built-in collation sequence 
** BINARY for the == operation.
**
** If successful, SQLITE_OK is returned and (*pp) set to point to
** the new changebatch object. If an error occurs, an SQLite error
** code is returned and the final value of (*pp) is undefined.
*/
int sqlite3changebatch_new(sqlite3 *db, sqlite3_changebatch **pp);

/*
** Argument p points to a buffer containing a changeset n bytes in
** size. Assuming no error occurs, this function returns SQLITE_OK
** if the changeset does not conflict with any changeset passed 
** to an sqlite3changebatch_add() call made on the same 
** sqlite3_changebatch* handle since the most recent call to
** sqlite3changebatch_zero(). If the changeset does conflict with 
** an earlier such changeset, SQLITE_CONSTRAINT is returned. Or, 
** if an error occurs, some other SQLite error code may be returned.
**
** One changeset is said to conflict with another if
** either:
**
**   * the two changesets contain operations (INSERT, UPDATE or 
**     DELETE) on the same row, identified by primary key, or
**
**   * the two changesets contain operations (INSERT, UPDATE or 
**     DELETE) on rows with identical values in any combination 
**     of fields constrained by a UNIQUE constraint.
**
** Even if this function returns SQLITE_CONFLICT, the current
** changeset is added to the internal data structures - so future
** calls to this function may conflict with it. If this function
** returns any result code other than SQLITE_OK or SQLITE_CONFLICT,
** the result of any future call to sqlite3changebatch_add() is
** undefined.
**
** Only changesets may be passed to this function. Passing a 
** patchset to this function results in an SQLITE_MISUSE error.
*/
int sqlite3changebatch_add(sqlite3_changebatch*, void *p, int n);

/*
** Zero a changebatch object. This causes the records of all earlier 
** calls to sqlite3changebatch_add() to be discarded.
*/
void sqlite3changebatch_zero(sqlite3_changebatch*);

/*
** Return a copy of the first argument passed to the sqlite3changebatch_new()
** call used to create the changebatch object passed as the only argument
** to this function.
*/
sqlite3 *sqlite3changebatch_db(sqlite3_changebatch*);

/*
** Delete a changebatch object.
*/
void sqlite3changebatch_delete(sqlite3_changebatch*);

#endif /* !defined(SQLITECHANGEBATCH_H_) */

# ifdef SQLITE_TEST
#   define SESSIONS_STRM_CHUNK_SIZE 64
# else
#   define SESSIONS_STRM_CHUNK_SIZE 1024
# endif
#endif

/*
** The three different types of changesets generated.
*/
#define SESSIONS_PATCHSET      0
#define SESSIONS_CHANGESET     1
#define SESSIONS_FULLCHANGESET 2

typedef struct SessionHook SessionHook;
struct SessionHook {
  void *pCtx;
  int (*xOld)(void*,int,sqlite3_value**);
  int (*xNew)(void*,int,sqlite3_value**);
  int (*xCount)(void*);
  int (*xDepth)(void*);

**
** Otherwise, the old.* record contains all primary key values and the 
** original values of any fields that have been modified. The new.* record 
** contains the new values of only those fields that have been modified.
*/ 
static int sessionAppendUpdate(
  SessionBuffer *pBuf,            /* Buffer to append to */
  int ePatchset,                  /* True for "patchset", 0 for "changeset" */
  sqlite3_stmt *pStmt,            /* Statement handle pointing at new row */
  SessionChange *p,               /* Object containing old values */
  u8 *abPK                        /* Boolean array - true for PK columns */
){
  int rc = SQLITE_OK;
  SessionBuffer buf2 = {0,0,0}; /* Buffer to accumulate new.* record in */
  int bNoop = 1;                /* Set to zero if any values are modified */

    }

    /* If at least one field has been modified, this is not a no-op. */
    if( bChanged ) bNoop = 0;

    /* Add a field to the old.* record. This is omitted if this modules is
    ** currently generating a patchset. */
    if( ePatchset!=SESSIONS_PATCHSET ){
      if( ePatchset==SESSIONS_FULLCHANGESET || bChanged || abPK[i] ){
        sessionAppendBlob(pBuf, pCsr, nAdvance, &rc);
      }else{
        sessionAppendByte(pBuf, 0, &rc);
      }
    }

    /* Add a field to the new.* record. Or the only record if currently
    ** generating a patchset.  */
    if( bChanged || (ePatchset==SESSIONS_PATCHSET && abPK[i]) ){
      sessionAppendCol(&buf2, pStmt, i, &rc);
    }else{
      sessionAppendByte(&buf2, 0, &rc);
    }

    pCsr += nAdvance;
  }

/*
** Append a DELETE change to the buffer passed as the first argument. Use
** the changeset format if argument bPatchset is zero, or the patchset
** format otherwise.
*/
static int sessionAppendDelete(
  SessionBuffer *pBuf,            /* Buffer to append to */
  int eChangeset,                 /* One of SESSIONS_CHANGESET etc. */
  SessionChange *p,               /* Object containing old values */
  int nCol,                       /* Number of columns in table */
  u8 *abPK                        /* Boolean array - true for PK columns */
){
  int rc = SQLITE_OK;

  sessionAppendByte(pBuf, SQLITE_DELETE, &rc);
  sessionAppendByte(pBuf, p->bIndirect, &rc);

  if( eChangeset!=SESSIONS_PATCHSET ){
    sessionAppendBlob(pBuf, p->aRecord, p->nRecord, &rc);
  }else{
    int i;
    u8 *a = p->aRecord;
    for(i=0; i<nCol; i++){
      u8 *pStart = a;
      int eType = *a++;

** This function is a no-op if *pRc is set to other than SQLITE_OK when it
** is called. Otherwise, append a serialized table header (part of the binary 
** changeset format) to buffer *pBuf. If an error occurs, set *pRc to an
** SQLite error code before returning.
*/
static void sessionAppendTableHdr(
  SessionBuffer *pBuf,            /* Append header to this buffer */
  int ePatchset,                  /* Use the patchset format if true */
  SessionTable *pTab,             /* Table object to append header for */
  int *pRc                        /* IN/OUT: Error code */
){
  /* Write a table header */
  sessionAppendByte(pBuf, (ePatchset==SESSIONS_PATCHSET) ? 'P' : 'T', pRc);
  sessionAppendVarint(pBuf, pTab->nCol, pRc);
  sessionAppendBlob(pBuf, pTab->abPK, pTab->nCol, pRc);
  sessionAppendBlob(pBuf, (u8 *)pTab->zName, (int)strlen(pTab->zName)+1, pRc);
}

/*
** Generate either a changeset (if argument bPatchset is zero) or a patchset
** (if it is non-zero) based on the current contents of the session object
** passed as the first argument.
**
** If no error occurs, SQLITE_OK is returned and the new changeset/patchset
** stored in output variables *pnChangeset and *ppChangeset. Or, if an error
** occurs, an SQLite error code is returned and both output variables set 
** to 0.
*/
static int sessionGenerateChangeset(
  sqlite3_session *pSession,      /* Session object */
  int ePatchset,                  /* One of SESSIONS_CHANGESET etc. */
  int (*xOutput)(void *pOut, const void *pData, int nData),
  void *pOut,                     /* First argument for xOutput */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
){
  sqlite3 *db = pSession->db;     /* Source database handle */
  SessionTable *pTab;             /* Used to iterate through attached tables */

      /* Check the table schema is still Ok. */
      rc = sessionTableInfo(db, pSession->zDb, zName, &nCol, 0, &azCol, &abPK);
      if( !rc && (pTab->nCol!=nCol || memcmp(abPK, pTab->abPK, nCol)) ){
        rc = SQLITE_SCHEMA;
      }

      /* Write a table header */
      sessionAppendTableHdr(&buf, ePatchset, pTab, &rc);

      /* Build and compile a statement to execute: */
      if( rc==SQLITE_OK ){
        rc = sessionSelectStmt(
            db, pSession->zDb, zName, nCol, azCol, abPK, &pSel);
      }

              int iCol;
              sessionAppendByte(&buf, SQLITE_INSERT, &rc);
              sessionAppendByte(&buf, p->bIndirect, &rc);
              for(iCol=0; iCol<nCol; iCol++){
                sessionAppendCol(&buf, pSel, iCol, &rc);
              }
            }else{
              rc = sessionAppendUpdate(&buf, ePatchset, pSel, p, abPK);
            }
          }else if( p->op!=SQLITE_INSERT ){
            rc = sessionAppendDelete(&buf, ePatchset, p, nCol, abPK);
          }
          if( rc==SQLITE_OK ){
            rc = sqlite3_reset(pSel);
          }

          /* If the buffer is now larger than SESSIONS_STRM_CHUNK_SIZE, pass
          ** its contents to the xOutput() callback. */

** using sqlite3_free().
*/
int sqlite3session_changeset(
  sqlite3_session *pSession,      /* Session object */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
){
  return sessionGenerateChangeset(
      pSession, SESSIONS_CHANGESET, 0, 0, pnChangeset, ppChangeset);
}

/*
** Streaming version of sqlite3session_changeset().
*/
int sqlite3session_changeset_strm(
  sqlite3_session *pSession,
  int (*xOutput)(void *pOut, const void *pData, int nData),
  void *pOut
){
  return sessionGenerateChangeset(
      pSession, SESSIONS_CHANGESET, xOutput, pOut, 0, 0);
}

/*
** Streaming version of sqlite3session_patchset().
*/
int sqlite3session_patchset_strm(
  sqlite3_session *pSession,
  int (*xOutput)(void *pOut, const void *pData, int nData),
  void *pOut
){
  return sessionGenerateChangeset(
      pSession, SESSIONS_PATCHSET, xOutput, pOut, 0, 0);
}

/*
** Obtain a patchset object containing all changes recorded by the 
** session object passed as the first argument.
**
** It is the responsibility of the caller to eventually free the buffer 
** using sqlite3_free().
*/
int sqlite3session_patchset(
  sqlite3_session *pSession,      /* Session object */
  int *pnPatchset,                /* OUT: Size of buffer at *ppChangeset */
  void **ppPatchset               /* OUT: Buffer containing changeset */
){
  return sessionGenerateChangeset(
      pSession, SESSIONS_PATCHSET, 0, 0, pnPatchset, ppPatchset);
}

int sqlite3session_fullchangeset(
  sqlite3_session *pSession,      /* Session object */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
){
  return sessionGenerateChangeset(
      pSession, SESSIONS_FULLCHANGESET, 0, 0, pnChangeset, ppChangeset);
}


/*
** Enable or disable the session object passed as the first argument.
*/
int sqlite3session_enable(sqlite3_session *pSession, int bEnable){
  int ret;
  sqlite3_mutex_enter(sqlite3_db_mutex(pSession->db));

  SessionTable *pTab;
  assert( xOutput==0 || (ppOut==0 && pnOut==0) );

  /* Create the serialized output changeset based on the contents of the
  ** hash tables attached to the SessionTable objects in list p->pList. 
  */
  for(pTab=pGrp->pList; rc==SQLITE_OK && pTab; pTab=pTab->pNext){
    int eChangeset = pGrp->bPatch ? SESSIONS_PATCHSET : SESSIONS_CHANGESET;
    int i;
    if( pTab->nEntry==0 ) continue;

    sessionAppendTableHdr(&buf, eChangeset, pTab, &rc);
    for(i=0; i<pTab->nChange; i++){
      SessionChange *p;
      for(p=pTab->apChange[i]; p; p=p->pNext){
        sessionAppendByte(&buf, p->op, &rc);
        sessionAppendByte(&buf, p->bIndirect, &rc);
        sessionAppendBlob(&buf, p->aRecord, p->nRecord, &rc);
      }

** the same session object is disabled, no INSERT record will appear in the
** changeset, even though the delete took place while the session was disabled.
** Or, if one field of a row is updated while a session is disabled, and 
** another field of the same row is updated while the session is enabled, the
** resulting changeset will contain an UPDATE change that updates both fields.
*/
int sqlite3session_changeset(
  sqlite3_session *pSession,      /* Session object */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
);

/*
** CAPI3REF: Generate A Full Changeset From A Session Object
**
** This function is similar to sqlite3session_changeset(), except that for
** each row affected by an UPDATE statement, all old.* values are recorded
** as part of the changeset, not just those modified.
*/
int sqlite3session_fullchangeset(
  sqlite3_session *pSession,      /* Session object */
  int *pnChangeset,               /* OUT: Size of buffer at *ppChangeset */
  void **ppChangeset              /* OUT: Buffer containing changeset */
);

/*
** CAPI3REF: Load The Difference Between Tables Into A Session 

** Tclcmd:  $session attach TABLE
**          $session changeset
**          $session delete
**          $session enable BOOL
**          $session indirect INTEGER
**          $session patchset
**          $session table_filter SCRIPT
**          $session fullchangeset
*/
static int SQLITE_TCLAPI test_session_cmd(
  void *clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  TestSession *p = (TestSession*)clientData;
  sqlite3_session *pSession = p->pSession;
  struct SessionSubcmd {
    const char *zSub;
    int nArg;
    const char *zMsg;

  } aSub[] = {
    { "attach",       1, "TABLE"       }, /* 0 */
    { "changeset",    0, ""            }, /* 1 */
    { "delete",       0, ""            }, /* 2 */
    { "enable",       1, "BOOL"        }, /* 3 */
    { "indirect",     1, "BOOL"        }, /* 4 */
    { "isempty",      0, ""            }, /* 5 */
    { "table_filter", 1, "SCRIPT"      }, /* 6 */
    { "patchset",     0, "",           }, /* 7 */
    { "diff",         2, "FROMDB TBL"  }, /* 8 */
    { "fullchangeset",0, ""            }, /* 9 */
    { 0 }
  };
  int iSub;
  int rc;

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");

      rc = sqlite3session_attach(pSession, zArg);
      if( rc!=SQLITE_OK ){
        return test_session_error(interp, rc, 0);
      }
      break;
    }

    case 9:        /* fullchangeset */
    case 7:        /* patchset */
    case 1: {      /* changeset */
      TestSessionsBlob o = {0, 0};
      if( iSub!=9 && test_tcl_integer(interp, SESSION_STREAM_TCL_VAR) ){
        void *pCtx = (void*)&o;
        if( iSub==7 ){
          rc = sqlite3session_patchset_strm(pSession, testStreamOutput, pCtx);
        }else{
          rc = sqlite3session_changeset_strm(pSession, testStreamOutput, pCtx);
        }
      }else{
        if( iSub==7 ){
          rc = sqlite3session_patchset(pSession, &o.n, &o.p);
        }else if( iSub==9 ){
          rc = sqlite3session_fullchangeset(pSession, &o.n, &o.p);
        }else{
          rc = sqlite3session_changeset(pSession, &o.n, &o.p);
        }
      }
      if( rc==SQLITE_OK ){
        Tcl_SetObjResult(interp, Tcl_NewByteArrayObj(o.p, o.n)); 
      }
      sqlite3_free(o.p);
      if( rc!=SQLITE_OK ){
        return test_session_error(interp, rc, 0);
      }
      break;
    }


    case 2:        /* delete */
      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
      break;

    case 3: {      /* enable */
      int val;

   || TCL_OK!=Tcl_GetIntFromObj(interp, Tcl_GetObjResult(interp), &res)
  ){
    Tcl_BackgroundError(interp);
  }

  Tcl_DecrRefCount(pEval);
  return res;
}

static int test_conflict_handler(
  void *pCtx,                     /* Pointer to TestConflictHandler structure */
  int eConf,                      /* DATA, MISSING, CONFLICT, CONSTRAINT */
  sqlite3_changeset_iter *pIter   /* Handle describing change and conflict */
){
  TestConflictHandler *p = (TestConflictHandler *)pCtx;

  }
  if( rc!=SQLITE_OK ){
    return test_session_error(interp, rc, 0);
  }

  return TCL_OK;
}

#include "sqlite3changebatch.h"

typedef struct TestChangebatch TestChangebatch;
struct TestChangebatch {
  sqlite3_changebatch *pChangebatch;
};

/*
** Tclcmd:  $changebatch add BLOB
**          $changebatch zero
**          $changebatch delete
*/
static int SQLITE_TCLAPI test_changebatch_cmd(
  void *clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  TestChangebatch *p = (TestChangebatch*)clientData;
  sqlite3_changebatch *pChangebatch = p->pChangebatch;
  struct SessionSubcmd {
    const char *zSub;
    int nArg;
    const char *zMsg;
    int iSub;
  } aSub[] = {
    { "add",          1, "CHANGESET",  }, /* 0 */
    { "zero",         0, "",           }, /* 1 */
    { "delete",       0, "",           }, /* 2 */
    { 0 }
  };
  int iSub;
  int rc;

  if( objc<2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "SUBCOMMAND ...");
    return TCL_ERROR;
  }
  rc = Tcl_GetIndexFromObjStruct(interp, 
      objv[1], aSub, sizeof(aSub[0]), "sub-command", 0, &iSub
  );
  if( rc!=TCL_OK ) return rc;
  if( objc!=2+aSub[iSub].nArg ){
    Tcl_WrongNumArgs(interp, 2, objv, aSub[iSub].zMsg);
    return TCL_ERROR;
  }

  switch( iSub ){
    case 0: {      /* add */
      int nArg;
      unsigned char *pArg = Tcl_GetByteArrayFromObj(objv[2], &nArg);
      rc = sqlite3changebatch_add(pChangebatch, pArg, nArg);
      if( rc!=SQLITE_OK && rc!=SQLITE_CONSTRAINT ){
        return test_session_error(interp, rc, 0);
      }else{
        extern const char *sqlite3ErrName(int);
        Tcl_SetObjResult(interp, Tcl_NewStringObj(sqlite3ErrName(rc), -1));
      }
      break;
    }

    case 1: {      /* zero */
      sqlite3changebatch_zero(pChangebatch);
      break;
    }

    case 2:        /* delete */
      Tcl_DeleteCommand(interp, Tcl_GetString(objv[0]));
      break;
  }

  return TCL_OK;
}

static void SQLITE_TCLAPI test_changebatch_del(void *clientData){
  TestChangebatch *p = (TestChangebatch*)clientData;
  sqlite3changebatch_delete(p->pChangebatch);
  ckfree((char*)p);
}

/*
** Tclcmd:  sqlite3changebatch CMD DB-HANDLE
*/
static int SQLITE_TCLAPI test_sqlite3changebatch(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3 *db;
  Tcl_CmdInfo info;
  int rc;                         /* sqlite3session_create() return code */
  TestChangebatch *p;             /* New wrapper object */

  if( objc!=3 ){
    Tcl_WrongNumArgs(interp, 1, objv, "CMD DB-HANDLE");
    return TCL_ERROR;
  }

  if( 0==Tcl_GetCommandInfo(interp, Tcl_GetString(objv[2]), &info) ){
    Tcl_AppendResult(interp, "no such handle: ", Tcl_GetString(objv[2]), 0);
    return TCL_ERROR;
  }
  db = *(sqlite3 **)info.objClientData;

  p = (TestChangebatch*)ckalloc(sizeof(TestChangebatch));
  memset(p, 0, sizeof(TestChangebatch));
  rc = sqlite3changebatch_new(db, &p->pChangebatch);
  if( rc!=SQLITE_OK ){
    ckfree((char*)p);
    return test_session_error(interp, rc, 0);
  }

  Tcl_CreateObjCommand(
      interp, Tcl_GetString(objv[1]), test_changebatch_cmd, (ClientData)p,
      test_changebatch_del
  );
  Tcl_SetObjResult(interp, objv[1]);
  return TCL_OK;
}

int TestSession_Init(Tcl_Interp *interp){
  struct Cmd {
    const char *zCmd;
    Tcl_ObjCmdProc *xProc;
  } aCmd[] = {
    { "sqlite3session", test_sqlite3session },

  int i;

  for(i=0; i<sizeof(aCmd)/sizeof(struct Cmd); i++){
    struct Cmd *p = &aCmd[i];
    Tcl_CreateObjCommand(interp, p->zCmd, p->xProc, 0, 0);
  }


  Tcl_CreateObjCommand(
      interp, "sqlite3changebatch", test_sqlite3changebatch, 0, 0
  );
  return TCL_OK;
}

#endif /* SQLITE_TEST && SQLITE_SESSION && SQLITE_PREUPDATE_HOOK */

  $(TOP)/ext/fts3/fts3.c \
  $(TOP)/ext/fts3/fts3_aux.c \
  $(TOP)/ext/fts3/fts3_expr.c \
  $(TOP)/ext/fts3/fts3_tokenizer.c \
  $(TOP)/ext/fts3/fts3_write.c \
  $(TOP)/ext/async/sqlite3async.c \
  $(TOP)/ext/session/sqlite3session.c \
  $(TOP)/ext/session/sqlite3changebatch.c \
  $(TOP)/ext/session/test_session.c 

# Header files used by all library source files.
#
HDR = \
   $(TOP)/src/btree.h \
   $(TOP)/src/btreeInt.h \