** a checkpoint (the remainder are stored as a system record in the LSM).
** See also LSM_CONFIG_MAX_FREELIST.
*/
#define LSM_MAX_FREELIST_ENTRIES 100

#define LSM_ATTEMPTS_BEFORE_PROTOCOL 10000











/*
** A string that can grow by appending.
*/
struct LsmString {
  lsm_env *pEnv;              /* Run-time environment */
  int n;                      /* Size of string.  -1 indicates error */
  int nAlloc;                 /* Space allocated for z[] */

** a checkpoint (the remainder are stored as a system record in the LSM).
** See also LSM_CONFIG_MAX_FREELIST.
*/
#define LSM_MAX_FREELIST_ENTRIES 100

#define LSM_ATTEMPTS_BEFORE_PROTOCOL 10000


/*
** Each entry stored in the LSM (or in-memory tree structure) has an
** associated mask of the following flags.
*/
#define LSM_START_DELETE 0x01     /* Start of open-ended delete range */
#define LSM_END_DELETE   0x02     /* End of open-ended delete range */
#define LSM_POINT_DELETE 0x04     /* Delete this key */
#define LSM_INSERT       0x08     /* Insert this key and value */

/*
** A string that can grow by appending.
*/
struct LsmString {
  lsm_env *pEnv;              /* Run-time environment */
  int n;                      /* Size of string.  -1 indicates error */
  int nAlloc;                 /* Space allocated for z[] */

struct TreeOld {
  u32 iShmid;                     /* Last shared-memory chunk in use by old */
  u32 iRoot;                      /* Offset of root node in shm file */
  u32 nHeight;                    /* Height of tree structure */
};

/*
** Flags for the TreeKey.flags variable.
*/
#define LSM_START_DELETE 0x01     /* Start of delete range */
#define LSM_END_DELETE   0x02     /* End of delete range */
#define LSM_POINT_DELETE 0x04     /* Delete this key */
#define LSM_INSERT       0x08     /* Insert this key and value */

#ifndef NDEBUG
/*
** assert() that a TreeKey.flags value is sane. Usage:
**
**   assert( assertFlagsOk(pTreeKey->flags) );
*/
static int assertFlagsOk(u8 keyflags){
................................................................................
  assert( (keyflags & LSM_END_DELETE)==0 
       || (keyflags & LSM_START_DELETE)==0 
       || (keyflags & LSM_POINT_DELETE)==0 
  );

  return 1;
}


#endif

/*
** Container for a key-value pair. Within the *-shm file, each key/value
** pair is stored in a single allocation (which may not actually be 
** contiguous in memory). Layout is the TreeKey structure, followed by
** the nKey bytes of key blob, followed by the nValue bytes of value blob
** (if nValue is non-negative).
*/
struct TreeKey {
  int nKey;                       /* Size of pKey in bytes */
  int nValue;                     /* Size of pValue. Or negative. */
  int flags;
};

#define TK_KEY(p) ((void *)&(p)[1])
#define TK_VAL(p) ((void *)(((u8 *)&(p)[1]) + (p)->nKey))

/*
** A single tree node. A node structure may contain up to 3 key/value
................................................................................
  int i;
  lsmStringExtend(pStr, nBlob*2);
  if( pStr->nAlloc==0 ) return;
  for(i=0; i<nBlob; i++){
    u8 c = ((u8*)pBlob)[i];
    if( c>='a' && c<='z' ){
      pStr->z[pStr->n++] = c;
    }else{
      pStr->z[pStr->n++] = "0123456789abcdef"[(c>>4)&0xf];
      pStr->z[pStr->n++] = "0123456789abcdef"[c&0xf];
    }
  }
  pStr->z[pStr->n] = 0;
}

................................................................................
** Append nIndent space (0x20) characters to string *pStr.
*/
static void lsmAppendIndent(LsmString *pStr, int nIndent){
  int i;
  lsmStringExtend(pStr, nIndent);
  for(i=0; i<nIndent; i++) lsmStringAppend(pStr, " ", 1);
}













void dump_node_contents(
  lsm_db *pDb,
  u32 iNode,                      /* Print out hte contents of this node */
  int nIndent,                    /* Number of spaces indentation */

  int nHeight                     /* Height: (0==leaf) (1==parent-of-leaf) */
){

  int i;
  int rc = LSM_OK;
  LsmString s;
  TreeNode *pNode;
  TreeBlob b = {0, 0};




  /* Append the nIndent bytes of space to string s. */
  lsmStringInit(&s, pDb->pEnv);
  if( nIndent ) lsmAppendIndent(&s, nIndent);

  pNode = (TreeNode *)treeShmptr(pDb, iNode, &rc);

  /* Append each key to string s. */
  for(i=0; i<3; i++){
    u32 iPtr = pNode->aiKeyPtr[i];
    if( iPtr ){
      TreeKey *pKey = treeShmkey(pDb, pNode->aiKeyPtr[i], TK_LOADKEY, &b, &rc);

      lsmAppendStrBlob(&s, TK_KEY(pKey), pKey->nKey);
      lsmStringAppend(&s, "     ", -1);
    }
  }

  printf("%s\n", s.z);

  lsmStringClear(&s);


  for(i=0; i<4 && nHeight>0; i++){
    u32 iPtr = getChildPtr(pNode, pDb->treehdr.root.iTransId, i);



    if( iPtr ){
      dump_node_contents(pDb, iPtr, nIndent + 2, nHeight-1);









    }
  }

  tblobFree(pDb, &b);
}

void dump_tree_contents(lsm_db *pDb, const char *zCaption){

  TreeRoot *p = &pDb->treehdr.root;
  printf("\n%s\n", zCaption);

  if( p->iRoot ){
    dump_node_contents(pDb, p->iRoot, 0, p->nHeight-1);
  }
  fflush(stdout);
}

#endif

/*
................................................................................
}

/*
** Return a pointer to the mapping of the TreeKey object that the cursor
** is pointing to. 
*/
static TreeKey *csrGetKey(TreeCursor *pCsr, TreeBlob *pBlob, int *pRc){
  return (TreeKey *)treeShmkey(pCsr->pDb,
      pCsr->apTreeNode[pCsr->iNode]->aiKeyPtr[pCsr->aiCell[pCsr->iNode]], 
      TK_LOADVAL, pBlob, pRc
  );


}

/*
** Save the current position of tree cursor pCsr.
*/
int lsmTreeCursorSave(TreeCursor *pCsr){
  int rc = LSM_OK;
................................................................................
       ** TreeNode */
      pCsr->iNode--;
      treeUpdatePtr(db, pCsr, iNew);
    }
  }
}

/*
** Insert a new entry into the in-memory tree.
**

** If the value of the 5th parameter, nVal, is negative, then a delete-marker
** is inserted into the tree. In this case the value pointer, pVal, must be

** NULL.
*/








































int lsmTreeInsert(
  lsm_db *pDb,                    /* Database handle */

  void *pKey,                     /* Pointer to key data */
  int nKey,                       /* Size of key data in bytes */
  void *pVal,                     /* Pointer to value data (or NULL) */
  int nVal                        /* Bytes in value data (or -ve for delete) */
){
  int rc = LSM_OK;                /* Return Code */
  TreeKey *pTreeKey;              /* New key-value being inserted */
  u32 iTreeKey;
  TreeRoot *p = &pDb->treehdr.root;



  assert( nVal>=0 || pVal==0 );
  assert_tree_looks_ok(LSM_OK, pTree);



#if 0
  dump_tree_contents(pDb, "before");
#endif



















































  /* Allocate and populate a new key-value pair structure */
  pTreeKey = newTreeKey(pDb, &iTreeKey, pKey, nKey, pVal, nVal, &rc);
  if( rc!=LSM_OK ) return rc;


  if( p->iRoot==0 ){
    /* The tree is completely empty. Add a new root node and install
    ** (pKey/nKey) as the middle entry. Even though it is a leaf at the
    ** moment, use newTreeNode() to allocate the node (i.e. allocate enough
    ** space for the fields used by interior nodes). This is because the
    ** treeInsert() routine may convert this node to an interior node. */
................................................................................
    TreeNode *pRoot = newTreeNode(pDb, &p->iRoot, &rc);
    if( rc==LSM_OK ){
      assert( p->nHeight==0 );
      pRoot->aiKeyPtr[1] = iTreeKey;
      p->nHeight = 1;
    }
  }else{
    TreeCursor csr;
    int res;

    /* Seek to the leaf (or internal node) that the new key belongs on */
    treeCursorInit(pDb, 0, &csr);
    lsmTreeCursorSeek(&csr, pKey, nKey, &res);

    if( res==0 ){
      /* The search found a match within the tree. */
      treeOverwriteKey(pDb, &csr, iTreeKey, &rc);
    }else{
      /* The cursor now points to the leaf node into which the new entry should
      ** be inserted. There may or may not be a free slot within the leaf for
      ** the new key-value pair. 
................................................................................
      int iSlot = csr.aiCell[csr.iNode] + (res<0);
      if( csr.iNode==0 ){
        rc = treeInsert(pDb, &csr, 0, iTreeKey, 0, iSlot);
      }else{
        rc = treeInsertLeaf(pDb, &csr, iTreeKey, iSlot);
      }
    }
    tblobFree(pDb, &csr.blob);
  }

#if 0
  dump_tree_contents(pDb, "after");
#endif


  assert_tree_looks_ok(rc, pTree);
  return rc;
}

























static int treeDeleteEntry(lsm_db *db, TreeCursor *pCsr, u32 iNewptr){
  TreeRoot *p = &db->treehdr.root;
  TreeNode *pNode = pCsr->apTreeNode[pCsr->iNode];
  int iSlot = pCsr->aiCell[pCsr->iNode];
  int bLeaf;
  int rc = LSM_OK;
................................................................................
    }
  }

  return rc;
}

/*
** Delete a range of keys from the tree structure.

**
** This is a two step process: 
**
**     1) Remove all entries currently stored in the tree that have keys
**        that fall into the deleted range.
**
**        TODO: There are surely good ways to optimize this step - removing 
................................................................................
  int rc = LSM_OK;
  int bDone = 0;
  TreeRoot *p = &db->treehdr.root;
  TreeBlob blob = {0, 0};

  /* The range must be sensible - that (key1 < key2). */
  assert( db->xCmp(pKey1, nKey1, pKey2, nKey2)<0 );










  /* Step 1. This loop runs until the tree contains no keys within the
  ** range being deleted. Or until an error occurs. */
  while( bDone==0 && rc==LSM_OK ){
    int res;
    TreeCursor csr;               /* Cursor to seek to first key in range */
    void *pDel; int nDel;         /* Key to (possibly) delete this iteration */
................................................................................
    bDone = 1;
    if( lsmTreeCursorValid(&csr) ){
      lsmTreeCursorKey(&csr, &pDel, &nDel);
      if( db->xCmp(pDel, nDel, pKey2, nKey2)<0 ) bDone = 0;
    }

    if( bDone==0 ){
#if 0
dump_tree_contents(db, "BEFORE");
fprintf(stderr, "DELETE %s\n", (char *)pDel);
static nCall = 0;
nCall ++;
fprintf(stderr, "%d\n", nCall);
#endif

      if( csr.iNode==(p->nHeight-1) ){
        /* The element to delete already lies on a leaf node */
        rc = treeDeleteEntry(db, &csr, 0);
      }else{
        /* 1. Overwrite the current key with a copy of the next key in the 
        **    tree (key N).
        **
................................................................................
        if( pKey ){
          rc = lsmTreeCursorSeek(&csr, TK_KEY(pKey), pKey->nKey, &res);
        }
        if( rc==LSM_OK ){
          assert( res==0 && csr.iNode==iNode );
          rc = lsmTreeCursorNext(&csr);
          if( rc==LSM_OK ){
#if 0
dump_tree_contents(db, "DURING");
#endif
            rc = treeDeleteEntry(db, &csr, 0);
          }
        }
      }
#if 0
dump_tree_contents(db, "AFTER");
#endif
    }

    /* Clean up any memory allocated by the cursor. */
    tblobFree(db, &csr.blob);
  }














  tblobFree(db, &blob);

  return rc;
}

/*
** Return, in bytes, the amount of memory currently used by the tree 
** structure.
*/
................................................................................

/*
** Move the cursor to the first (bLast==0) or last (bLast!=0) entry in the
** in-memory tree.
*/
int lsmTreeCursorEnd(TreeCursor *pCsr, int bLast){
  lsm_db *pDb = pCsr->pDb;
  TreeHeader *pHdr = &pDb->treehdr;
  TreeRoot *pRoot = pCsr->pRoot;
  int rc = LSM_OK;

  u32 iNodePtr;
  pCsr->iNode = -1;

  /* Discard any saved position data */
................................................................................
  int res = 0;
  int rc;

  rc = treeCursorRestore(pCsr, &res);
  if( res==0 ){
    TreeKey *pTreeKey = csrGetKey(pCsr, &pCsr->blob, &rc);
    if( rc==LSM_OK ){
      *pnVal = pTreeKey->nValue;
      if( pTreeKey->nValue>=0 ){
        *ppVal = TK_VAL(pTreeKey);
      }else{
        *ppVal = 0;

      }
    }
  }else{
    *ppVal = 0;
    *pnVal = 0;
  }

................................................................................
    memcpy(&pShm->hdr1, &pDb->treehdr, sizeof(TreeHeader));
  }
  pShm->bWriter = 0;
  intArrayFree(pDb->pEnv, &pDb->rollback);

  return LSM_OK;
}

struct TreeOld {
  u32 iShmid;                     /* Last shared-memory chunk in use by old */
  u32 iRoot;                      /* Offset of root node in shm file */
  u32 nHeight;                    /* Height of tree structure */
};









#ifndef NDEBUG
/*
** assert() that a TreeKey.flags value is sane. Usage:
**
**   assert( assertFlagsOk(pTreeKey->flags) );
*/
static int assertFlagsOk(u8 keyflags){
................................................................................
  assert( (keyflags & LSM_END_DELETE)==0 
       || (keyflags & LSM_START_DELETE)==0 
       || (keyflags & LSM_POINT_DELETE)==0 
  );

  return 1;
}

static int assert_delete_ranges_match(lsm_db *);
#endif

/*
** Container for a key-value pair. Within the *-shm file, each key/value
** pair is stored in a single allocation (which may not actually be 
** contiguous in memory). Layout is the TreeKey structure, followed by
** the nKey bytes of key blob, followed by the nValue bytes of value blob
** (if nValue is non-negative).
*/
struct TreeKey {
  int nKey;                       /* Size of pKey in bytes */
  int nValue;                     /* Size of pValue. Or negative. */
  u8 flags;                       /* Various LSM_XXX flags */
};

#define TK_KEY(p) ((void *)&(p)[1])
#define TK_VAL(p) ((void *)(((u8 *)&(p)[1]) + (p)->nKey))

/*
** A single tree node. A node structure may contain up to 3 key/value
................................................................................
  int i;
  lsmStringExtend(pStr, nBlob*2);
  if( pStr->nAlloc==0 ) return;
  for(i=0; i<nBlob; i++){
    u8 c = ((u8*)pBlob)[i];
    if( c>='a' && c<='z' ){
      pStr->z[pStr->n++] = c;
    }else if( c!=0 || nBlob==1 || i!=(nBlob-1) ){
      pStr->z[pStr->n++] = "0123456789abcdef"[(c>>4)&0xf];
      pStr->z[pStr->n++] = "0123456789abcdef"[c&0xf];
    }
  }
  pStr->z[pStr->n] = 0;
}

................................................................................
** Append nIndent space (0x20) characters to string *pStr.
*/
static void lsmAppendIndent(LsmString *pStr, int nIndent){
  int i;
  lsmStringExtend(pStr, nIndent);
  for(i=0; i<nIndent; i++) lsmStringAppend(pStr, " ", 1);
}

static void strAppendFlags(LsmString *pStr, u8 flags){
  char zFlags[5];

  zFlags[0] = (flags & LSM_END_DELETE)   ? 'E' : '.';
  zFlags[1] = (flags & LSM_START_DELETE) ? 'S' : '.';
  zFlags[2] = (flags & LSM_POINT_DELETE) ? 'P' : '.';
  zFlags[3] = (flags & LSM_INSERT)       ? 'I' : '.';
  zFlags[4] = ':';

  lsmStringAppend(pStr, zFlags, 5);
}

void dump_node_contents(
  lsm_db *pDb,
  u32 iNode,                      /* Print out the contents of this node */
  char *zPath,                    /* Path from root to this node */
  int nPath,                      /* Number of bytes in zPath */
  int nHeight                     /* Height: (0==leaf) (1==parent-of-leaf) */
){
  const char *zSpace = "                                           ";
  int i;
  int rc = LSM_OK;
  LsmString s;
  TreeNode *pNode;
  TreeBlob b = {0, 0};

  pNode = (TreeNode *)treeShmptr(pDb, iNode, &rc);

  if( nHeight==0 ){
    /* Append the nIndent bytes of space to string s. */
    lsmStringInit(&s, pDb->pEnv);




    /* Append each key to string s. */
    for(i=0; i<3; i++){
      u32 iPtr = pNode->aiKeyPtr[i];
      if( iPtr ){
        TreeKey *pKey = treeShmkey(pDb, pNode->aiKeyPtr[i], TK_LOADKEY, &b,&rc);
        strAppendFlags(&s, pKey->flags);
        lsmAppendStrBlob(&s, TK_KEY(pKey), pKey->nKey);
        lsmStringAppend(&s, "     ", -1);
      }
    }


    printf("%.*sleaf%.*s: %s\n", nPath, zPath, 20-nPath-4, zSpace, s.z);
    lsmStringClear(&s);

  }else{
    for(i=0; i<4 && nHeight>0; i++){
      u32 iPtr = getChildPtr(pNode, pDb->treehdr.root.iTransId, i);
      zPath[nPath] = i+'0';
      zPath[nPath+1] = '/';

      if( iPtr ){
        dump_node_contents(pDb, iPtr, zPath, nPath+2, nHeight-1);
      }
      if( i!=3 && pNode->aiKeyPtr[i] ){
        TreeKey *pKey = treeShmkey(pDb, pNode->aiKeyPtr[i], TK_LOADKEY, &b,&rc);
        lsmStringInit(&s, pDb->pEnv);
        strAppendFlags(&s, pKey->flags);
        lsmAppendStrBlob(&s, TK_KEY(pKey), pKey->nKey);
        printf("%.*s%.*s: %s\n", nPath+1, zPath, 20-nPath-1, zSpace, s.z);
        lsmStringClear(&s);
      }
    }
  }

  tblobFree(pDb, &b);
}

void dump_tree_contents(lsm_db *pDb, const char *zCaption){
  char zPath[64];
  TreeRoot *p = &pDb->treehdr.root;
  printf("\n%s\n", zCaption);
  zPath[0] = '/';
  if( p->iRoot ){
    dump_node_contents(pDb, p->iRoot, zPath, 1, p->nHeight-1);
  }
  fflush(stdout);
}

#endif

/*
................................................................................
}

/*
** Return a pointer to the mapping of the TreeKey object that the cursor
** is pointing to. 
*/
static TreeKey *csrGetKey(TreeCursor *pCsr, TreeBlob *pBlob, int *pRc){
  TreeKey *pRet = (TreeKey *)treeShmkey(pCsr->pDb,
      pCsr->apTreeNode[pCsr->iNode]->aiKeyPtr[pCsr->aiCell[pCsr->iNode]], 
      TK_LOADVAL, pBlob, pRc
  );
  assertFlagsOk(pRet->flags);
  return pRet;
}

/*
** Save the current position of tree cursor pCsr.
*/
int lsmTreeCursorSave(TreeCursor *pCsr){
  int rc = LSM_OK;
................................................................................
       ** TreeNode */
      pCsr->iNode--;
      treeUpdatePtr(db, pCsr, iNew);
    }
  }
}

static int treeNextIsEndDelete(lsm_db *db, TreeCursor *pCsr){
  TreeNode *pNode;

  int iNode = pCsr->iNode;
  int iCell = pCsr->aiCell[iNode]+1;


  /* Cursor currently points to a leaf node. */

  assert( pCsr->iNode==(db->treehdr.root.nHeight-1) );

  while( iNode>=0 ){
    TreeNode *pNode = pCsr->apTreeNode[iNode];
    if( iCell<3 && pNode->aiKeyPtr[iCell] ){
      int rc = LSM_OK;
      TreeKey *pKey = treeShmptr(db, pNode->aiKeyPtr[iCell], &rc);
      assert( rc==LSM_OK );
      return ((pKey->flags & LSM_END_DELETE) ? 1 : 0);
    }
    iNode--;
    iCell = pCsr->aiCell[iNode];
  }

  return 0;
}

static int treePrevIsStartDelete(lsm_db *db, TreeCursor *pCsr){
  TreeNode *pNode;
  int iNode = pCsr->iNode;

  /* Cursor currently points to a leaf node. */
  assert( pCsr->iNode==(db->treehdr.root.nHeight-1) );

  while( iNode>=0 ){
    TreeNode *pNode = pCsr->apTreeNode[iNode];
    int iCell = pCsr->aiCell[iNode]-1;
    if( iCell>=0 && pNode->aiKeyPtr[iCell] ){
      int rc = LSM_OK;
      TreeKey *pKey = treeShmptr(db, pNode->aiKeyPtr[iCell], &rc);
      assert( rc==LSM_OK );
      return ((pKey->flags & LSM_START_DELETE) ? 1 : 0);
    }
    iNode--;
  }

  return 0;
}


static int treeInsertEntry(
  lsm_db *pDb,                    /* Database handle */
  int flags,                      /* Flags associated with entry */
  void *pKey,                     /* Pointer to key data */
  int nKey,                       /* Size of key data in bytes */
  void *pVal,                     /* Pointer to value data (or NULL) */
  int nVal                        /* Bytes in value data (or -ve for delete) */
){
  int rc = LSM_OK;                /* Return Code */
  TreeKey *pTreeKey;              /* New key-value being inserted */
  u32 iTreeKey;
  TreeRoot *p = &pDb->treehdr.root;
  TreeCursor csr;                 /* Cursor to seek to pKey/nKey */
  int res;                        /* Result of seek operation on csr */

  assert( nVal>=0 || pVal==0 );
  assert_tree_looks_ok(LSM_OK, pTree);
  assert( flags==LSM_INSERT       || flags==LSM_POINT_DELETE 
       || flags==LSM_START_DELETE || flags==LSM_END_DELETE 
  );
#if 0
  dump_tree_contents(pDb, "before");
#endif

  if( p->iRoot ){
    TreeKey *pRes;                /* Key at end of seek operation */
    treeCursorInit(pDb, 0, &csr);

    /* Seek to the leaf (or internal node) that the new key belongs on */
    rc = lsmTreeCursorSeek(&csr, pKey, nKey, &res);
    pRes = csrGetKey(&csr, &csr.blob, &rc);
    if( rc!=LSM_OK ) return rc;

    if( flags==LSM_START_DELETE ){
      /* When inserting a start-delete-range entry, if the key that
      ** occurs immediately before the new entry is already a START_DELETE,
      ** then the new entry is not required.  */
      if( (res<=0 && (pRes->flags & LSM_START_DELETE))
       || (res>0  && treePrevIsStartDelete(pDb, &csr))
      ){ 
        goto insert_entry_out;
      }
    }else if( flags==LSM_END_DELETE ){
      /* When inserting an start-delete-range entry, if the key that
      ** occurs immediately after the new entry is already an END_DELETE,
      ** then the new entry is not required.  */
      if( (res<0  && treeNextIsEndDelete(pDb, &csr))
       || (res>=0 && (pRes->flags & LSM_END_DELETE))
      ){
        goto insert_entry_out;
      }
    }

    if( res==0 && (flags & (LSM_END_DELETE|LSM_START_DELETE)) ){
      if( pRes->flags & LSM_INSERT ){
        nVal = pRes->nValue;
        pVal = TK_VAL(pRes);
      }
      flags = flags | pRes->flags;
    }

    if( flags & (LSM_INSERT|LSM_POINT_DELETE) ){
      if( (res<0 && (pRes->flags & LSM_START_DELETE))
       || (res>0 && (pRes->flags & LSM_END_DELETE)) 
      ){
        flags = flags | (LSM_END_DELETE|LSM_START_DELETE);
      }else if( res==0 ){
        flags = flags | (pRes->flags & (LSM_END_DELETE|LSM_START_DELETE));
      }
    }
  }else{
    memset(&csr, 0, sizeof(TreeCursor));
  }

  /* Allocate and populate a new key-value pair structure */
  pTreeKey = newTreeKey(pDb, &iTreeKey, pKey, nKey, pVal, nVal, &rc);
  if( rc!=LSM_OK ) return rc;
  pTreeKey->flags = flags;

  if( p->iRoot==0 ){
    /* The tree is completely empty. Add a new root node and install
    ** (pKey/nKey) as the middle entry. Even though it is a leaf at the
    ** moment, use newTreeNode() to allocate the node (i.e. allocate enough
    ** space for the fields used by interior nodes). This is because the
    ** treeInsert() routine may convert this node to an interior node. */
................................................................................
    TreeNode *pRoot = newTreeNode(pDb, &p->iRoot, &rc);
    if( rc==LSM_OK ){
      assert( p->nHeight==0 );
      pRoot->aiKeyPtr[1] = iTreeKey;
      p->nHeight = 1;
    }
  }else{







    if( res==0 ){
      /* The search found a match within the tree. */
      treeOverwriteKey(pDb, &csr, iTreeKey, &rc);
    }else{
      /* The cursor now points to the leaf node into which the new entry should
      ** be inserted. There may or may not be a free slot within the leaf for
      ** the new key-value pair. 
................................................................................
      int iSlot = csr.aiCell[csr.iNode] + (res<0);
      if( csr.iNode==0 ){
        rc = treeInsert(pDb, &csr, 0, iTreeKey, 0, iSlot);
      }else{
        rc = treeInsertLeaf(pDb, &csr, iTreeKey, iSlot);
      }
    }

  }

#if 0
  dump_tree_contents(pDb, "after");
#endif
 insert_entry_out:
  tblobFree(pDb, &csr.blob);
  assert_tree_looks_ok(rc, pTree);
  return rc;
}

/*
** Insert a new entry into the in-memory tree.
**
** If the value of the 5th parameter, nVal, is negative, then a delete-marker
** is inserted into the tree. In this case the value pointer, pVal, must be
** NULL.
*/
int lsmTreeInsert(
  lsm_db *pDb,                    /* Database handle */
  void *pKey,                     /* Pointer to key data */
  int nKey,                       /* Size of key data in bytes */
  void *pVal,                     /* Pointer to value data (or NULL) */
  int nVal                        /* Bytes in value data (or -ve for delete) */
){
  int flags;
  if( nVal<0 ){
    flags = LSM_POINT_DELETE;
  }else{
    flags = LSM_INSERT;
  }

  return treeInsertEntry(pDb, flags, pKey, nKey, pVal, nVal);
}

static int treeDeleteEntry(lsm_db *db, TreeCursor *pCsr, u32 iNewptr){
  TreeRoot *p = &db->treehdr.root;
  TreeNode *pNode = pCsr->apTreeNode[pCsr->iNode];
  int iSlot = pCsr->aiCell[pCsr->iNode];
  int bLeaf;
  int rc = LSM_OK;
................................................................................
    }
  }

  return rc;
}

/*
** Delete a range of keys from the tree structure (i.e. the lsm_delete_range()
** function, not lsm_delete()).
**
** This is a two step process: 
**
**     1) Remove all entries currently stored in the tree that have keys
**        that fall into the deleted range.
**
**        TODO: There are surely good ways to optimize this step - removing 
................................................................................
  int rc = LSM_OK;
  int bDone = 0;
  TreeRoot *p = &db->treehdr.root;
  TreeBlob blob = {0, 0};

  /* The range must be sensible - that (key1 < key2). */
  assert( db->xCmp(pKey1, nKey1, pKey2, nKey2)<0 );
  assert( assert_delete_ranges_match(db) );

#if 0
  static int nCall = 0;
  printf("\n");
  nCall++;
  printf("%d delete %s .. %s\n", nCall, (char *)pKey1, (char *)pKey2);
  dump_tree_contents(db, "before delete");
#endif

  /* Step 1. This loop runs until the tree contains no keys within the
  ** range being deleted. Or until an error occurs. */
  while( bDone==0 && rc==LSM_OK ){
    int res;
    TreeCursor csr;               /* Cursor to seek to first key in range */
    void *pDel; int nDel;         /* Key to (possibly) delete this iteration */
................................................................................
    bDone = 1;
    if( lsmTreeCursorValid(&csr) ){
      lsmTreeCursorKey(&csr, &pDel, &nDel);
      if( db->xCmp(pDel, nDel, pKey2, nKey2)<0 ) bDone = 0;
    }

    if( bDone==0 ){








      if( csr.iNode==(p->nHeight-1) ){
        /* The element to delete already lies on a leaf node */
        rc = treeDeleteEntry(db, &csr, 0);
      }else{
        /* 1. Overwrite the current key with a copy of the next key in the 
        **    tree (key N).
        **
................................................................................
        if( pKey ){
          rc = lsmTreeCursorSeek(&csr, TK_KEY(pKey), pKey->nKey, &res);
        }
        if( rc==LSM_OK ){
          assert( res==0 && csr.iNode==iNode );
          rc = lsmTreeCursorNext(&csr);
          if( rc==LSM_OK ){



            rc = treeDeleteEntry(db, &csr, 0);
          }
        }
      }



    }

    /* Clean up any memory allocated by the cursor. */
    tblobFree(db, &csr.blob);
  }

  /* dump_tree_contents(db, "during delete"); */

  /* Now insert the START_DELETE and END_DELETE keys. */
  if( rc==LSM_OK ){
    rc = treeInsertEntry(db, LSM_START_DELETE, pKey1, nKey1, 0, -1);
  }
  /* dump_tree_contents(db, "during delete 2"); */
  if( rc==LSM_OK ){
    rc = treeInsertEntry(db, LSM_END_DELETE, pKey2, nKey2, 0, -1);
  }

  /* dump_tree_contents(db, "after delete"); */

  tblobFree(db, &blob);
  assert( assert_delete_ranges_match(db) );
  return rc;
}

/*
** Return, in bytes, the amount of memory currently used by the tree 
** structure.
*/
................................................................................

/*
** Move the cursor to the first (bLast==0) or last (bLast!=0) entry in the
** in-memory tree.
*/
int lsmTreeCursorEnd(TreeCursor *pCsr, int bLast){
  lsm_db *pDb = pCsr->pDb;

  TreeRoot *pRoot = pCsr->pRoot;
  int rc = LSM_OK;

  u32 iNodePtr;
  pCsr->iNode = -1;

  /* Discard any saved position data */
................................................................................
  int res = 0;
  int rc;

  rc = treeCursorRestore(pCsr, &res);
  if( res==0 ){
    TreeKey *pTreeKey = csrGetKey(pCsr, &pCsr->blob, &rc);
    if( rc==LSM_OK ){
      if( pTreeKey->flags & LSM_INSERT ){
        *pnVal = pTreeKey->nValue;
        *ppVal = TK_VAL(pTreeKey);
      }else{
        *ppVal = 0;
        *pnVal = -1;
      }
    }
  }else{
    *ppVal = 0;
    *pnVal = 0;
  }

................................................................................
    memcpy(&pShm->hdr1, &pDb->treehdr, sizeof(TreeHeader));
  }
  pShm->bWriter = 0;
  intArrayFree(pDb->pEnv, &pDb->rollback);

  return LSM_OK;
}

static int assert_delete_ranges_match(lsm_db *db){
  int prev = 0;
  TreeBlob blob = {0, 0};
  TreeCursor csr;               /* Cursor used to iterate through tree */
  int rc;
  u32 iTransId = db->treehdr.root.iTransId;

  treeCursorInit(db, 0, &csr);
  for( rc = lsmTreeCursorEnd(&csr, 0);
       rc==LSM_OK && lsmTreeCursorValid(&csr);
       rc = lsmTreeCursorNext(&csr)
  ){
    TreeKey *pKey = csrGetKey(&csr, &blob, &rc);
    if( rc!=LSM_OK ) break;
    assert( ((prev&LSM_START_DELETE)==0)==((pKey->flags&LSM_END_DELETE)==0) );
    prev = pKey->flags;
  }

  tblobFree(csr.pDb, &csr.blob);

  return 1;
}