Fixed minor bug "replace"-mappings. Removed some logging messages.
[idzebra-moved-to-github.git] / isamc / merge-d.c
index 13958ed..196f0e3 100644 (file)
@@ -3,18 +3,34 @@
  * See the file LICENSE for details.
  * Heikki Levanto
  *
- * merge-d.c: merge routines for isamd
+ * $Id: merge-d.c,v 1.18 1999-08-25 18:09:24 heikki Exp $
  *
- * todo
- *  - merge when needed
- *  - single-entry optimizing
+ * missing
+ *
+ * optimize
+ *  - Input filter: Eliminate del-ins pairs, tell if only one entry (or none)
+ *  - single-entry optimizing (keep the one entry in the dict, no block)
  *  - study and optimize block sizes (later)
+ *  - Clean up the different ways diffs are handled in writing and reading
+ *  - Keep a merge-count in the firstpp, and if the block has already been
+ *    merged, reduce it to a larger size even if it could fit in a small one!
+ *  - Keep minimum freespace in the category table, and use that in reduce!
+ *  - pass a space-needed for separateDiffBlock and reduce to be able to 
+ *    reserve more room for diffs, or to force a separate (larger?) block
+ *  - Idea: Simplify the structure, so that the first block is always diffs.
+ *    On small blocks, that is all we have. Once a block has been merged, we
+ *    allocate the first main block and a (new) firstblock ffor diffs. From
+ *    that point on the word has two blocks for it. 
+ *  - On allocating more blocks (in append), check the order of blocks, and
+ *    if needed, swap them. 
+ *  - In merge, merge also with the input data.
+ *  - Write a routine to save/load indexes into a block, save only as many 
+ *    bytes as needed (size, diff, diffindexes)
  *
  * bugs
- *  not yet ready
  *
  * caveat
- *  There is aconfusion about the block addresses. cat or type is the category,
+ *  There is a confusion about the block addresses. cat or type is the category,
  *  pos or block is the block number. pp structures keep these two separate,
  *  and combine when saving the pp. The next pointer in the pp structure is
  *  also a combined address, but needs to be combined every time it is needed,
  *  in that order. This conflicts with the order these are often mentioned in 
  *  the debug log calls, and other places, leading to small mistakes here
  *  and there. 
+ *
+ *  Needs cleaning! The way diff blocks are handled in append and reading is
+ *  quite different, and likely to give maintenance problems.
+ *
+ *  log levels (set isamddebug=x in zebra.cfg (or what ever cfg file you use) )
+ *    0 = no logging. Default
+ *    1 = no logging here. isamd logs overall statistics
+ *    2 = Each call to isamd_append with start address and no more
+ *    3 = Start and type of append, start of merge, and result of append
+ *    4 = Block allocations
+ *    5 = Block-level operations (read/write)
+ *    6 = Details about diff blocks etc.
+ *    7 = Log each record as it passes the system (once)
+ *    8 = Log raw and (de)coded data
+ *    9 = Anything else that may be useful
+ *   .. = Anything needed to hunt a specific bug
+ *  (note that all tests in the code are like debug>3, which means 4 or above!)
+ *
+ * Design for the new and improved isamd
+ * Key points:
+ *  - The first block is only diffs, no straight data
+ *  - Additional blocks are straight data
+ *  - When a diff block gets filled up, a data block is created by
+ *    merging the diffs with the data
+ *
+ * Structure
+ *  - Isamd_pp: buffer for diffs and for data
+ *              keep both pos, type, and combined address
+ *              routine to set the address
+ *  - diffbuf: lengths as short ints, or bytes for small blocks
+ *  - keys are of key_struct, not just a number of bytes.
+ *
+ * Routines
+ *  - isamd_append
+ *    - create_new_block if needed
+ *    - append_diffs
+ *      - load_diffs 
+ *      - get diffend, start encoding
+ *      - while input data
+ *        - encode it
+ *        - if no room, then realloc block in larger size
+ *        - if still no room, merge and exit
+ *        - append in the block
+ *
+ * - merge
+ *   - just as before, except that merges also input data directly
+ *   - writes into new data blocks
+ *       
+ *      
+ * - isamd.c: load firstpp, load datablock
+ *            save firstpp, save datablock
+ * - Readlength, writelength - handling right size of len fields
+ * - isamd_read_main_item: take also a merge input structure, and merge it too
+ * - prefilter: cache two inputs, and check if they cancel.
+ * - single-item optimization
+ * 
+ * questions: Should we realloc firstblocks in a different size as the main
+ * blocks. Makes a sideways seek, which is bound to be slowe. But saves some
+ * update time. Compromise: alloc the first one in the size of the datablock,
+ * but increase if necessary. Large blocks get a large diff, ok. Small ones
+ * may get an extra seek in read, but save merges.
  */
 
+
+#define NEW_ISAM_D 0  /* not yet ready to delete the old one! */
+
 #include <stdlib.h>
 #include <assert.h>
 #include <string.h>
@@ -58,38 +138,73 @@ static char *hexdump(unsigned char *p, int len, char *buff) {
   return buff;
 }
 
+#ifndef NEW_ISAM_D
+/* The next many lines are the old ISAM_D. Works, but not optimal */
 
 static int separateDiffBlock(ISAMD_PP pp)
 {
-  return ( 0 != pp->next);
+  int limit = sizeof(int) + 8;
+  if (pp->next) 
+     return 1;  /* multi-block chains always have a separate diff block */
+  return ( pp->size + limit >= pp->is->method->filecat[pp->cat].bsize);
+  /* make sure there is at least room for the length and one diff. if not, */
+  /* it goes to a separate block. Assumes max diff is 8 bytes. Not         */
+  /* unreaalistic in large data sets, where first sysno may be very large, */
+  /* and even the first seqno may be quite something. */
+  
+  /* todo: Make the limit adjustable in the filecat table ! */
 }
 
 
+/**************************************************************
+ * Reading 
+ **************************************************************/
+
 static void getDiffInfo(ISAMD_PP pp, int diffidx)
 { /* builds the diff info structures from a diffblock */
-   int maxinfos = pp->is->method->filecat[pp->cat].bsize / 5 +1;
+   int maxinfos = pp->is->method->filecat[pp->cat].bsize / 5 +2;
     /* Each diff takes at least 5 bytes. Probably more, but this is safe */
    int i=1;  /* [0] is used for the main data */
    int diffsz= maxinfos * sizeof(struct ISAMD_DIFF_s);
-   pp->diffinfo = xmalloc( diffsz );
+
+   pp->diffinfo = xmalloc( diffsz ); 
    memset(pp->diffinfo,'\0',diffsz);
-   if (pp->is->method->debug > 4)
-     logf(LOG_LOG,"isamd_getDiffInfo: %d (%d:%d), ix=%d mx=%d",
+   if (pp->is->method->debug > 5)   
+      logf(LOG_LOG,"isamd_getDiffInfo: %d (%d:%d), ix=%d mx=%d",
          isamd_addr(pp->pos, pp->cat), pp->cat, pp->pos, diffidx,maxinfos);
+   assert(pp->diffbuf);
 
    while (i<maxinfos) 
    {  
       if ( diffidx+sizeof(int) > pp->is->method->filecat[pp->cat].bsize )
       {
-         if (pp->is->method->debug > 4)
+         if (pp->is->method->debug > 5)
            logf(LOG_LOG,"isamd_getDiffInfo:Near end (no room for len) at ix=%d n=%d",
                diffidx, i);
          return; /* whole block done */
       }
       memcpy( &pp->diffinfo[i].maxidx, &pp->diffbuf[diffidx], sizeof(int) );
+
+      if (pp->is->method->debug > 5)
+        logf(LOG_LOG,"isamd_getDiffInfo: max=%d ix=%d dbuf=%p",
+          pp->diffinfo[i].maxidx, diffidx, pp->diffbuf);
+
+      if ( (pp->is->method->debug > 0) &&
+         (pp->diffinfo[i].maxidx > pp->is->method->filecat[pp->cat].bsize) )
+      { /* bug-hunting, this fails on some long runs that log too much */
+         logf(LOG_LOG,"Bad MaxIx!!! %s:%d: diffidx=%d", 
+                       __FILE__,__LINE__, diffidx);
+         logf(LOG_LOG,"i=%d maxix=%d bsz=%d", i, pp->diffinfo[i].maxidx,
+                       pp->is->method->filecat[pp->cat].bsize);
+         logf(LOG_LOG,"pp=%d=%d:%d  pp->nx=%d=%d:%d",
+                       isamd_addr(pp->pos,pp->cat), pp->pos, pp->cat,
+                       pp->next, isamd_type(pp->next), isamd_block(pp->next) );                      
+      }
+      assert(pp->diffinfo[i].maxidx <= pp->is->method->filecat[pp->cat].bsize+1);
+
       if (0==pp->diffinfo[i].maxidx)
       {
-         if (pp->is->method->debug > 4)
+         if (pp->is->method->debug > 5)  //!!! 4
            logf(LOG_LOG,"isamd_getDiffInfo:End mark at ix=%d n=%d",
                diffidx, i);
          return; /* end marker */
@@ -97,7 +212,7 @@ static void getDiffInfo(ISAMD_PP pp, int diffidx)
       diffidx += sizeof(int);
       pp->diffinfo[i].decodeData = (*pp->is->method->code_start)(ISAMD_DECODE);
       pp->diffinfo[i].diffidx = diffidx;
-      if (pp->is->method->debug > 4)
+      if (pp->is->method->debug > 5)
         logf(LOG_LOG,"isamd_getDiff[%d]:%d-%d %s",
           i,diffidx-sizeof(int),pp->diffinfo[i].maxidx,
           hexdump((char *)&pp->diffbuf[diffidx-4],8,0) );
@@ -106,7 +221,7 @@ static void getDiffInfo(ISAMD_PP pp, int diffidx)
         return; /* whole block done */
       ++i;
    }
-   assert ("too many diff sequences in the block");
+   assert (!"too many diff sequences in the block");
 }
 
 static void loadDiffs(ISAMD_PP pp)
@@ -118,15 +233,22 @@ static void loadDiffs(ISAMD_PP pp)
    if (pp->diffs & 1 )
    { /* separate diff block, load it */
       pp->diffbuf= xmalloc( pp->is->method->filecat[pp->cat].bsize);
-      diffaddr=pp->diffs/2;
+      diffaddr=isamd_addr(pp->diffs/2, pp->cat);
       isamd_read_block (pp->is, isamd_type(diffaddr), 
                                 isamd_block(diffaddr), pp->diffbuf );
       diffidx= ISAMD_BLOCK_OFFSET_N; 
+      if (pp->is->method->debug > 4)
+        logf(LOG_LOG,"isamd_LoadDiffs: loaded block %d=%d:%d, d=%d ix=%d",
+          diffaddr, isamd_type(diffaddr),isamd_block(diffaddr), 
+          pp->diffs,diffidx);
    }
    else
    { /* integrated block, just set the pointers */
      pp->diffbuf = pp->buf;
      diffidx = pp->size;  /* size is the beginning of diffs, diffidx the end*/
+      if (pp->is->method->debug > 4)
+        logf(LOG_LOG,"isamd_LoadDiffs: within %d=%d:%d, d=%d ix=%d ",
+          isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, pp->diffs, diffidx);
    }
    getDiffInfo(pp,diffidx);
 } /* loadDiffs */
@@ -135,10 +257,17 @@ static void loadDiffs(ISAMD_PP pp)
 void isamd_free_diffs(ISAMD_PP pp)
 {
   int i;
+  if (pp->is->method->debug > 5)
+     logf(LOG_LOG,"isamd_free_diffs: pp=%p di=%p", pp, pp->diffinfo);
   if (!pp->diffinfo) 
     return;
-  for (i=0;pp->diffinfo[i].decodeData;i++) 
-      (*pp->is->method->code_stop)(ISAMD_DECODE,pp->diffinfo[i].decodeData);    
+  for (i=1;pp->diffinfo[i].decodeData;i++) 
+  {
+      if (pp->is->method->debug > 8)
+         logf(LOG_LOG,"isamd_free_diffs [%d]=%p",i, 
+                       pp->diffinfo[i].decodeData);
+      (*pp->is->method->code_stop)(ISAMD_DECODE,pp->diffinfo[i].decodeData);
+  } 
   xfree(pp->diffinfo);
   if (pp->diffbuf != pp->buf)
     xfree (pp->diffbuf);  
@@ -168,7 +297,7 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
      { /* 0 is special case, main data. */
         keyptr=(char*) &(pp->diffinfo[0].key);
         pp->diffinfo[0].mode = ! isamd_read_main_item(pp,&keyptr);
-        if (pp->is->method->debug > 4)
+        if (pp->is->method->debug > 7)
           logf(LOG_LOG,"isamd_read_item: read main %d.%d (%x.%x)",
             pp->diffinfo[0].key.sysno, pp->diffinfo[0].key.seqno,
             pp->diffinfo[0].key.sysno, pp->diffinfo[0].key.seqno);
@@ -176,7 +305,7 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
      winner = 0;
      for (i=1; (!retry) && (pp->diffinfo[i].decodeData); i++)
      {
-        if (pp->is->method->debug > 4)
+        if (pp->is->method->debug > 8)
           logf(LOG_LOG,"isamd_read_item: considering d%d %d.%d ix=%d mx=%d",
                i, pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
                   pp->diffinfo[i].diffidx,   pp->diffinfo[i].maxidx);
@@ -191,7 +320,7 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
            pp->diffinfo[i].diffidx += codeptr-codestart;
            pp->diffinfo[i].mode = pp->diffinfo[i].key.seqno & 1;
            pp->diffinfo[i].key.seqno = pp->diffinfo[i].key.seqno >>1 ;
-           if (pp->is->method->debug > 4)
+           if (pp->is->method->debug > 7)
              logf(LOG_LOG,"isamd_read_item: read diff[%d] %d.%d (%x.%x)",i,
                pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
                pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno);
@@ -203,7 +332,7 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
             cmp=-1; /* end of main sequence, take all diffs */
           if (cmp<0)
           {
-             if (pp->is->method->debug > 4)
+             if (pp->is->method->debug > 8)
                logf(LOG_LOG,"isamd_read_item: ins %d<%d %d.%d (%x.%x) < %d.%d (%x.%x)",
                  i, winner,
                  pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
@@ -213,14 +342,14 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
              if (pp->diffinfo[i].mode)  /* insert diff, should always be */
                winner = i;
              else
-               assert("delete diff for nonexisting item");  
-               /* is an assert too steep here?*/
+               assert(!"delete diff for nonexisting item");  
+               /* is an assert too steep here? Not really.*/
           } /* earlier key */
           else if (cmp==0)
           {
              if (!pp->diffinfo[i].mode) /* delete diff. should always be */
              {
-                if (pp->is->method->debug > 4)
+                if (pp->is->method->debug > 8)
                   logf(LOG_LOG,"isamd_read_item: del %d at%d %d.%d (%x.%x)",
                     i, winner,
                     pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
@@ -228,12 +357,13 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
                 pp->diffinfo[winner].key.sysno=0; /* delete it */
              }
              else
-                if (pp->is->method->debug > 4)
+                if (pp->is->method->debug > 2)
                   logf(LOG_LOG,"isamd_read_item: duplicate ins %d at%d %d.%d (%x.%x)",
                     i, winner,
                     pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
                     pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno);
                 /* skip the insert, since we already have it in the base */
+                /* Should we fail an assertion here??? */
              pp->diffinfo[i].key.sysno=0; /* done with the delete */
              retry=1; /* start all over again */
           } /* matching key */
@@ -244,7 +374,7 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
 
   if ( pp->diffinfo[winner].key.sysno)
   {
-    if (pp->is->method->debug > 4)
+    if (pp->is->method->debug > 7)
       logf(LOG_LOG,"isamd_read_item: got %d  %d.%d (%x.%x)",
         winner,
         pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno,
@@ -256,7 +386,7 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
   } 
   else 
   {
-    if (pp->is->method->debug > 4)
+    if (pp->is->method->debug > 7)
       logf(LOG_LOG,"isamd_read_item: eof w=%d  %d.%d (%x.%x)",
         winner,
         pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno,
@@ -268,6 +398,9 @@ int isamd_read_item (ISAMD_PP pp, char **dst)
    
 } /* isamd_read_item */
 
+/*****************************************************************
+ * Support routines 
+ *****************************************************************/
 
 static void isamd_reduceblock(ISAMD_PP pp)
 /* takes a large block, and reduces its category if possible */
@@ -275,22 +408,220 @@ static void isamd_reduceblock(ISAMD_PP pp)
 {
    if (pp->pos)
       return; /* existing block, do not touch */
-   if (pp->is->method->debug > 2)
+   if (pp->is->method->debug > 5)  
      logf(LOG_LOG,"isamd_reduce: start p=%d c=%d sz=%d",
        pp->pos, pp->cat, pp->size); 
    while ( ( pp->cat > 0 ) && (!pp->next) && 
            (pp->offset < pp->is->method->filecat[pp->cat-1].bsize ) )
       pp->cat--;
    pp->pos = isamd_alloc_block(pp->is, pp->cat);
-   if (pp->is->method->debug > 2)
+   if (pp->is->method->debug > 5) 
      logf(LOG_LOG,"isamd_reduce:  got  p=%d c=%d sz=%d",
        pp->pos, pp->cat, pp->size);    
 } /* reduceblock */
 
 
+
+static int save_first_pp ( ISAMD_PP firstpp)
+{
+   isamd_reduceblock(firstpp);
+   isamd_buildfirstblock(firstpp);
+   isamd_write_block(firstpp->is,firstpp->cat,firstpp->pos,firstpp->buf);
+   return isamd_addr(firstpp->pos,firstpp->cat);
+}
+
+static void save_last_pp (ISAMD_PP pp)
+{
+   pp->next = 0;/* just to be sure */
+   isamd_buildlaterblock(pp);
+   isamd_write_block(pp->is,pp->cat,pp->pos,pp->buf);
+}
+
+
+static int save_both_pps (ISAMD_PP firstpp, ISAMD_PP pp)
+{
+   /* order of things: Better to save firstpp first, if there are just two */
+   /* blocks, but last if there are blocks in between, as these have already */
+   /* been saved... optimise later (that's why this is in its own func...*/
+   int retval = save_first_pp(firstpp);
+   if (firstpp!=pp){ 
+      save_last_pp(pp);
+      isamd_pp_close(pp);
+   }
+   isamd_pp_close(firstpp);
+   return retval;
+} /* save_both_pps */
+
+static ISAMD_PP read_diff_block(ISAMD_PP firstpp, int* p_diffidx)
+{ /* reads the diff block (if separate) and sets diffidx right */
+   ISAMD_PP pp=firstpp;
+   int i;
+   int diffidx;   
+   if (pp->diffs == 0)
+   { /* no diffs yet, create room for them */
+      if (separateDiffBlock(firstpp))
+      { /* create a new block */
+         pp=isamd_pp_open(pp->is,isamd_addr(0,firstpp->cat));
+         pp->pos = isamd_alloc_block(pp->is, pp->cat);
+         firstpp->diffs = pp->pos*2 +1;
+         diffidx = pp->size = pp->offset = ISAMD_BLOCK_OFFSET_N;
+         if (pp->is->method->debug >5) 
+             logf(LOG_LOG,"isamd_appd: alloc diff  (d=%d) %d=%d:%d ix=%d",
+                   firstpp->diffs,
+                   isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
+                   diffidx);
+      }
+      else
+      { /* prepare to append diffs in head */
+        diffidx = pp->size;
+        pp->diffs = diffidx *2 +0; 
+        i=diffidx; /* make an end marker */
+        while ( ( i < pp->is->method->filecat[pp->cat].bsize) && 
+                ( i <= diffidx + sizeof(int)))
+            pp->buf[i++]='\0';
+        if (pp->is->method->debug >5) 
+             logf(LOG_LOG,"isamd_appd: set up diffhead  (d=%d) %d=%d:%d ix=%d",
+                   firstpp->diffs,
+                   isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
+                   diffidx);
+      }
+   } /* new */
+   else
+   { /* existing diffs */
+      if (pp->diffs & 1)
+      { /* diffs in a separate block, load it */
+        pp=isamd_pp_open(pp->is, isamd_addr(firstpp->diffs/2,pp->cat));
+        diffidx = pp->offset= pp->size;
+        if (pp->is->method->debug >5) 
+           logf(LOG_LOG,"isamd_appd: loaded diff (d=%d) %d=%d:%d ix=%d",
+                 firstpp->diffs,
+                 isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
+                 diffidx);
+      }
+      else
+      { /* diffs within the nead */
+         diffidx= pp->diffs/2;
+         if (pp->is->method->debug >5)  
+            logf(LOG_LOG,"isamd_appd: diffs in head d=%d %d=%d:%d ix=%d sz=%d",
+                     pp->diffs,
+                     isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
+                     diffidx, pp->size);
+      }
+   } /* diffs exist already */
+   *p_diffidx = diffidx;
+   return pp;
+} /* read_diff_block */
+
+
+
+
+/*******************************************************************
+ * Building main blocks (no diffs)
+ *******************************************************************/
+
+
+
+static ISAMD_PP get_new_main_block( ISAMD_PP firstpp, ISAMD_PP pp)
+{  /* allocates a new block for the main data, and links it in */
+   int newblock;
+   if (firstpp==pp) 
+   { /* special case: it was the first block. Save much later */
+      if (0==firstpp->pos)
+      { /* firstpp not allocated yet, do so now, */
+        /* to keep blocks in order. Don't save yet, though */
+         firstpp->pos = isamd_alloc_block(pp->is, firstpp->cat);
+      }
+      newblock = isamd_alloc_block(pp->is, firstpp->cat);
+      firstpp->next = isamd_addr(newblock,firstpp->cat);
+        /* keep the largest category */
+      pp=isamd_pp_open(pp->is,isamd_addr(0,firstpp->cat));/*don't load*/
+      pp->pos=newblock; 
+      pp->size = pp->offset = ISAMD_BLOCK_OFFSET_N; 
+      pp->next=0;
+      if (pp->is->method->debug >3) 
+         logf(LOG_LOG,"isamd_g_mainblk: Alloc2 f=%d=%d:%d n=%d=%d:%d",
+            isamd_addr(firstpp->pos,firstpp->cat), 
+            firstpp->cat, firstpp->pos,
+            isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos );
+   }
+   else
+   { /* it was not the first block */
+      newblock = isamd_alloc_block(pp->is, firstpp->cat);
+      pp->next = isamd_addr(newblock,firstpp->cat);
+      if (pp->is->method->debug >3) 
+         logf(LOG_LOG,"isamd_build: Alloc1 after p=%d=%d:%d->%d=%d:%d",
+            isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos,
+            isamd_addr(newblock,pp->cat), pp->cat, newblock );
+      isamd_buildlaterblock(pp);
+      isamd_write_block(pp->is,pp->cat,pp->pos,pp->buf);
+      pp->size = pp->offset = ISAMD_BLOCK_OFFSET_N;
+      pp->next=0;
+      pp->cat = firstpp->cat;
+      pp->pos = newblock;
+      pp->cat = firstpp->cat; /* is already, never mind */
+   }
+  return pp;
+} /* get_new_main_block */
+
+
+static ISAMD_PP  append_main_item(ISAMD_PP firstpp, 
+                                  ISAMD_PP pp, 
+                                  struct it_key *i_key,
+                                  void *encoder_data)
+{  /* appends one item in the main data block, allocates new if needed */
+   char *i_item= (char *) i_key;  /* same as char */
+   char *i_ptr=i_item;
+   char codebuff[128];
+   char *c_ptr = codebuff;
+   int codelen;
+   char hexbuff[64];
+
+   int maxsize = pp->is->method->filecat[pp->is->max_cat].bsize; 
+
+   c_ptr=codebuff;
+   i_ptr=i_item;
+   (*pp->is->method->code_item)(ISAMD_ENCODE, encoder_data, &c_ptr, &i_ptr);
+   codelen = c_ptr - codebuff;
+   assert ( (codelen<128) && (codelen>0));
+   if (pp->is->method->debug >7)
+      logf(LOG_LOG,"isamd:build: coded into %s  (nk=%d)",
+          hexdump(codebuff, c_ptr-codebuff,hexbuff), firstpp->numKeys+1);
+
+   if (pp->offset + codelen > maxsize )
+   { /* oops, block full - get a new one */
+      pp =  get_new_main_block( firstpp, pp );
+      /* reset encoging and code again */
+      (*pp->is->method->code_reset)(encoder_data);
+      c_ptr=codebuff;
+      i_ptr=i_item;
+      (*pp->is->method->code_item)(ISAMD_ENCODE, encoder_data, &c_ptr, &i_ptr);
+      codelen = c_ptr - codebuff;
+      assert ( (codelen<128) && (codelen>0));
+      if (pp->is->method->debug >7)
+         logf(LOG_LOG,"isamd:build: recoded into %s  (nk=%d)",
+             hexdump(codebuff, c_ptr-codebuff,hexbuff), firstpp->numKeys+1);
+   } /* block full */    
+   
+   /* write the data into pp, now we must have room */ 
+   memcpy(&(pp->buf[pp->offset]),codebuff,codelen);
+   pp->offset += codelen;
+   pp->size += codelen;
+   firstpp->numKeys++;
+   /* clear the next 4 bytes in block, to avoid confusions with diff lens */
+   /* dirty, it should not be done here, but something slips somewhere, and */
+   /* I hope this fixes it...  - Heikki */
+   codelen = pp->offset;
+   while ( (codelen < maxsize ) && (codelen <= pp->offset+4) )
+     pp->buf[codelen++] = '\0';
+   return pp;    
+} /* append_main_item */
+
+
 static int isamd_build_first_block(ISAMD is, ISAMD_I data) 
 {
-   char i_item[128];    /* one input item */
+   struct it_key i_key;  /* input key */
+   char *i_item= (char *) &i_key;  /* same as char */
    char *i_ptr=i_item;
    int i_more =1;
    int i_mode;     /* 0 for delete, 1 for insert */ 
@@ -298,30 +629,28 @@ static int isamd_build_first_block(ISAMD is, ISAMD_I data)
    ISAMD_PP firstpp;
    ISAMD_PP pp;
    void *encoder_data;
-   int maxsize;
-   
-   char codebuff[128];
-   char *c_ptr = codebuff;
-   int codelen;
    
    char hexbuff[64];
-   int newblock;
-   int retval=0;
    
+   ++(is->files[0].no_fbuilds);
+
    firstpp=pp=isamd_pp_open(is, isamd_addr(0,is->max_cat));
    firstpp->size = firstpp->offset = ISAMD_BLOCK_OFFSET_1;
+   
    encoder_data=(*is->method->code_start)(ISAMD_ENCODE);
-   maxsize = is->method->filecat[is->max_cat].bsize; 
    
-   if (is->method->debug >3)
-      logf(LOG_LOG,"isamd_bld start: p=%d c=%d sz=%d maxsz=%d ",
-         pp->pos, pp->cat, pp->size, maxsize);
+   if (is->method->debug >2)
+      logf(LOG_LOG,"isamd_bld start: p=%d=%d:%d sz=%d maxsz=%d ",
+         isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
+         pp->size, pp->is->method->filecat[pp->is->max_cat].bsize); 
 
    /* read first input */
    i_ptr = i_item;
    i_more = (*data->read_item)(data->clientData, &i_ptr, &i_mode); 
+   if (i_more)
+     assert( i_ptr-i_item == sizeof(i_key) );
 
-   if (is->method->debug >3)
+   if (pp->is->method->debug >7)
       logf(LOG_LOG,"isamd: build_fi start: m=%d %s",
          i_mode, hexdump(i_item,i_ptr-i_item,hexbuff) );
 
@@ -329,100 +658,178 @@ static int isamd_build_first_block(ISAMD is, ISAMD_I data)
    { 
       if (i_mode!=0) 
       { /* ignore deletes here, should not happen */
-      
-         c_ptr=codebuff;
-         i_ptr=i_item;
-         (*is->method->code_item)(ISAMD_ENCODE, encoder_data, &c_ptr, &i_ptr);
-         codelen = c_ptr - codebuff;
-         assert ( (codelen<128) && (codelen>0));
-         if (is->method->debug >3)
-            logf(LOG_LOG,"isamd:build: coded into %s  (nk=%d)",
-                hexdump(codebuff, c_ptr-codebuff,hexbuff), firstpp->numKeys+1);
-     
-         if (pp->offset + codelen > maxsize )
-         { /* oops, block full - get a new one */
-            if (firstpp==pp) 
-            { /* special case: it was the first block. Save much later */
-               if (0==firstpp->pos)
-               { /* firstpp not allocated yet, do so now, */
-                 /* to keep blocks in order. Don't save yet, though */
-                  firstpp->pos = isamd_alloc_block(is, firstpp->cat);
-               }
-               newblock = isamd_alloc_block(is, firstpp->cat);
-               firstpp->next = isamd_addr(newblock,firstpp->cat);
-                 /* keep the largest category */
-               pp=isamd_pp_open(is,isamd_addr(0,firstpp->cat));/*don't load*/
-               pp->pos=newblock; 
-               pp->size = pp->offset = ISAMD_BLOCK_OFFSET_N; 
-               pp->next=0;
-               if (is->method->debug >3)
-                  logf(LOG_LOG,"isamd_build: Alloc2 f=%d (%d:%d) n=%d(%d:%d)",
-                     isamd_addr(firstpp->pos,firstpp->cat), 
-                     firstpp->cat, firstpp->pos,
-                     isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos );
-            }
-            else
-            { /* it was not the first block */
-               newblock = isamd_alloc_block(is, firstpp->cat);
-               pp->next = isamd_addr(newblock,firstpp->cat);
-               isamd_buildlaterblock(pp);
-               isamd_write_block(is,pp->cat,pp->pos,pp->buf);
-               pp->size = pp->offset = ISAMD_BLOCK_OFFSET_N;
-               pp->next=0;
-               pp->cat = firstpp->cat;
-               pp->pos = isamd_block(firstpp->next);
-            }
-            /* reset encoging and code again */
-            (*is->method->code_reset)(encoder_data);
-            c_ptr=codebuff;
-            i_ptr=i_item;
-            (*is->method->code_item)(ISAMD_ENCODE, encoder_data, &c_ptr, &i_ptr);
-            codelen = c_ptr - codebuff;
-            assert ( (codelen<128) && (codelen>0));
-            if (is->method->debug >3)
-               logf(LOG_LOG,"isamd:build: recoded into %s  (nk=%d)",
-                   hexdump(codebuff, c_ptr-codebuff,hexbuff), firstpp->numKeys+1);
-         } /* block full */    
-         
-         /* write the data into pp, now we have room */ 
-         memcpy(&(pp->buf[pp->offset]),codebuff,codelen);
-         pp->offset += codelen;
-         pp->size += codelen;
-         firstpp->numKeys++;
+         pp= append_main_item(firstpp, pp, &i_key, encoder_data);      
       } /* not delete */
       
       /* (try to) read the next item */
       i_ptr = i_item;
       i_more = (*data->read_item)(data->clientData, &i_ptr, &i_mode); 
       
-      if ( (i_more) && (is->method->debug >3) )
-         logf(LOG_LOG,"isamd: build_fi start: m=%d %s",
+      if ( (i_more) && (pp->is->method->debug >7) )
+         logf(LOG_LOG,"isamd: build_fi read: m=%d %s",
             i_mode, hexdump(i_item,i_ptr-i_item,hexbuff) );
       
-      
    } /* i_more */
+   (*is->method->code_stop)(ISAMD_ENCODE, encoder_data);
 
-   /* order of things: Better to save firstpp first, if there are just two */
-   /* blocks, but last if there are blocks in between, as these have already */
-   /* been saved... optimise later */
+   return save_both_pps( firstpp, pp );
 
-   /* save the first block */
-   isamd_reduceblock(firstpp);
-   isamd_buildfirstblock(firstpp);
-   isamd_write_block(is,firstpp->cat,firstpp->pos,firstpp->buf);   
-   retval = isamd_addr(firstpp->pos,firstpp->cat);
+} /* build_first_block */
 
-   if (firstpp!=pp){  /* and the last one */
-      pp->next = 0;/* just to be sure */
-      isamd_buildlaterblock(pp);
-      isamd_write_block(is,pp->cat,pp->pos,pp->buf);
-      isamd_pp_close(pp);
-   }
 
-   isamd_pp_close(firstpp);
-   
-   return retval;
-} /* build_first_block */
+/***************************************************************
+ * Merging diffs 
+ ***************************************************************/
+
+static int merge ( ISAMD_PP *p_firstpp,   /* first pp of the chain */
+                   ISAMD_PP *p_pp,        /* diff block */
+                   struct it_key *p_key ) /* not used yet */
+{
+  ISAMD_PP readpp = *p_firstpp;
+  int diffidx;  
+  int killblk=0;
+  struct it_key r_key;
+  char * r_ptr;
+  int r_more = 1;
+  ISAMD_PP firstpp;  /* the new first, the one we write into */
+  ISAMD_PP pp;
+  void *encoder_data;
+
+  ++(readpp->is->files[0].no_merges);
+     
+  /* set up diffs as they should be for reading */
+  readpp->offset= ISAMD_BLOCK_OFFSET_1; 
+  
+  if ( (*p_firstpp)->diffs & 1 )
+  { /* separate diff block in *p_pp */
+     killblk = readpp->diffs/2;
+     diffidx /*size*/ = readpp->is->method->filecat[readpp->cat].bsize; 
+     readpp->diffbuf= xmalloc( diffidx); /* copy diffs to where read wants*/
+     memcpy( readpp->diffbuf, &((*p_pp)->buf[0]), diffidx);
+     diffidx = ISAMD_BLOCK_OFFSET_N;
+     if (readpp->is->method->debug >2) 
+     { 
+        logf(LOG_LOG,"isamd_merge:separate diffs at ix=%d", 
+                diffidx);
+        logf(LOG_LOG,"isamd_merge: dbuf=%p (from %p) pp=%p", 
+                 readpp->diffbuf, &((*p_pp)->buf[0]), (*p_pp) );
+     }
+  }
+  else
+  { /* integrated diffs */
+     assert ( *p_pp == *p_firstpp );  /* can only be in the first block */
+     diffidx=readpp->size;
+     readpp->diffs = diffidx*2+0;
+     readpp->diffbuf=readpp->buf; 
+     if (readpp->is->method->debug >2)  
+         logf(LOG_LOG,"isamd_merge:local diffs at %d: %s", 
+           diffidx,hexdump(&(readpp->diffbuf[diffidx]),8,0));
+  }
+
+  getDiffInfo(readpp,diffidx);
+  if (readpp->is->method->debug >8) 
+         logf(LOG_LOG,"isamd_merge: diffinfo=%p", readpp->diffinfo);
+  
+
+  if (killblk) 
+  {  /* we had a separate diff block, release it, we have copied the data */
+     isamd_release_block(readpp->is, readpp->cat, killblk);
+     isamd_pp_close (*p_pp);
+     if (readpp->is->method->debug >3)  
+         logf(LOG_LOG,"isamd_merge: released diff block %d=%d:%d",
+              isamd_addr(killblk,readpp->cat), readpp->cat, killblk );
+  }
+
+
+  /* release our data block. Do before reading, when pos is stable ! */
+  killblk=readpp->pos;
+  assert(killblk);
+  isamd_release_block(readpp->is, readpp->cat, killblk);
+  if (readpp->is->method->debug >3)   
+      logf(LOG_LOG,"isamd_merge: released old firstblock %d (%d:%d)",
+               isamd_addr(killblk,readpp->cat), readpp->cat, killblk );
+
+  r_ptr= (char *) &r_key;
+  r_more = isamd_read_item( readpp, &r_ptr);
+  if (!r_more)  
+  { /* oops, all data has been deleted! what to do??? */
+    /* never mind, we have at least one more delta to add to the block */
+    /* pray that is not a delete as well... */
+    r_key.sysno = 0;
+    r_key.seqno = 0;
+     if (readpp->is->method->debug >3) 
+         logf(LOG_LOG,"isamd_merge:all data has been deleted (nk=%d) ",
+            readpp->numKeys);
+    assert (readpp->numKeys == 0);
+  }
+
+
+  /* set up the new blocks for simple writing */
+  firstpp=pp=isamd_pp_open(readpp->is,isamd_addr(0, readpp->is->max_cat));
+  firstpp->size = firstpp->offset = ISAMD_BLOCK_OFFSET_1;
+  encoder_data = (*pp->is->method->code_start)(ISAMD_ENCODE);
+  
+  while (r_more)
+  {
+     if (readpp->is->method->debug >6) 
+         logf(LOG_LOG,"isamd_merge: got key %d.%d",
+           r_key.sysno, r_key.seqno );
+     pp= append_main_item(firstpp, pp, &r_key, encoder_data);
+
+     if ( (readpp->pos != killblk ) && (0!=readpp->pos) )
+     {  /* pos can get to 0 at end of main seq, if still diffs left...*/
+        if (readpp->is->method->debug >3)  
+            logf(LOG_LOG,"isamd_merge: released block %d (%d:%d) now %d=%d:%d",
+                isamd_addr(killblk,readpp->cat), readpp->cat, killblk,
+                isamd_addr(readpp->pos,readpp->cat),readpp->cat, readpp->pos );
+        isamd_release_block(readpp->is, readpp->cat, readpp->pos);
+        killblk=readpp->pos;
+     }
+
+     /* (try to) read next item */
+     r_ptr= (char *) &r_key;
+     r_more = isamd_read_item( readpp, &r_ptr);
+
+  } /* while read */
+  
+  /* set things up so that append can continue */
+  isamd_reduceblock(firstpp);
+  firstpp->diffs=0; 
+
+  if (firstpp!=pp) 
+  { /* the last data block is of no interest any more */
+    save_last_pp(pp);
+    if (readpp->is->method->debug >4) 
+        logf(LOG_LOG,"isamd_merge: saved last block %d=%d:%d",
+              isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos);
+    isamd_pp_close(pp);
+  }
+
+  if (readpp->is->method->debug >5) 
+        logf(LOG_LOG,"isamd_merge: closing readpp %d=%d:%d di=%p",
+              isamd_addr(readpp->pos,readpp->cat), readpp->cat, readpp->pos,
+              readpp->diffinfo);
+  isamd_pp_close(readpp); /* pos is 0 by now, at eof. close works anyway */
+
+  (*firstpp->is->method->code_stop)(ISAMD_ENCODE, encoder_data);
+  
+  *p_firstpp = firstpp; 
+
+  if (readpp->is->method->debug >2)  
+      logf(LOG_LOG,"isamd_merge: merge ret  %d=%d:%d nx=%d=%d:%d d=%d=2*%d+%d",
+            isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos,
+            pp->next, isamd_type(pp->next), isamd_block(pp->next),
+            pp->diffs, pp->diffs/2, pp->diffs &1 );
+  return 0; 
+  
+} /* merge */
+
+
+
+/***************************************************************
+ * Appending diffs 
+ ***************************************************************/
 
 
 
@@ -438,59 +845,23 @@ static int append_diffs(ISAMD is, ISAMD_P ipos, ISAMD_I data)
    ISAMD_PP pp;
    void *encoder_data;
    char hexbuff[64];
-   int retval=ipos;  /* by default we do not change the firstblock addr */
    int diffidx=0;
    int maxsize=0;
    int difflenidx;
    char codebuff[128];
    char *c_ptr = codebuff;
    int codelen;
+   int merge_rc;
+   int mergecount=0;
 
-   pp=firstpp=isamd_pp_open(is, ipos);
+   ++(is->files[0].no_appds);
 
-   /* TODO: Turn these ifs around! Check first diffs==0, and create new */
-   /* according to separateDiffBlock. if !=0, read according to its type */
-   /* bit. Much more robust this way around! */
-   
-   if (separateDiffBlock(firstpp))
-   { /* multi-block item, get the diff block */
-     if (firstpp->diffs==0) 
-     { /* allocate first diff block */
-       pp=isamd_pp_open(is,isamd_addr(0,firstpp->cat));
-       pp->pos = isamd_alloc_block(pp->is, pp->cat);
-       firstpp->diffs = pp->pos*2 +1;
-       diffidx = pp->size = pp->offset = ISAMD_BLOCK_OFFSET_N;
-       if (is->method->debug >3) 
-           logf(LOG_LOG,"isamd_appd: alloc diff  (%d) %d %d:%d ix=%d",
-                 firstpp->diffs,
-                 isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
-                 diffidx);
-     }
-     else
-     { /* find pointers within the existing block */
-        pp=isamd_pp_open(is, firstpp->diffs/2);
-        diffidx = pp->offset= pp->size;
-        if (is->method->debug >3) 
-           logf(LOG_LOG,"isamd_appd: load diff (%d) %d (%d:%d) ix=%d",
-                 firstpp->diffs,
-                 isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
-                 diffidx);
-     }
-   } 
-   else
-   { /* single-block item, get idx right */
-     diffidx= pp->diffs/2;
-     if (is->method->debug >3) 
-        logf(LOG_LOG,"isamd_appd: diffs in head %d (%d:%d) ix=%d sz=%d",
-                 isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos, 
-                 diffidx, pp->size);
-     if (0==diffidx)
-     { /* no diffs yet, make them */
-        diffidx = pp->size;
-        pp->diffs = diffidx *2 +0;  
-     }
-   }
-   
+   firstpp=isamd_pp_open(is, ipos);
+   if (is->method->debug >2) 
+      logf(LOG_LOG,"isamd_appd: Start ipos=%d=%d:%d d=%d=%d*2+%d nk=%d",
+        ipos, isamd_type(ipos), isamd_block(ipos),
+        firstpp->diffs, firstpp->diffs/2, firstpp->diffs & 1, firstpp->numKeys);
+   pp=read_diff_block(firstpp, &diffidx);
    encoder_data=(*is->method->code_start)(ISAMD_ENCODE);
    maxsize = is->method->filecat[pp->cat].bsize; 
    
@@ -501,31 +872,67 @@ static int append_diffs(ISAMD is, ISAMD_P ipos, ISAMD_I data)
    i_ptr = i_item;
    i_more = (*data->read_item)(data->clientData, &i_ptr, &i_mode); 
 
-   if (is->method->debug >3)
+   if (is->method->debug >6)
       logf(LOG_LOG,"isamd_appd: start with m=%d %s",
          i_mode, hexdump(i_item,i_ptr-i_item,hexbuff) );
 
    while (i_more)
    {     
+      /* store the mode bit inside key */
       assert( ((i_key.seqno<<1)>>1) == i_key.seqno); /* can spare the bit */
-      i_key.seqno = i_key.seqno * 2 + i_mode;
+      i_key.seqno = i_key.seqno * 2 + i_mode;  
+
       c_ptr=codebuff;
       i_ptr=i_item;
       (*is->method->code_item)(ISAMD_ENCODE, encoder_data, &c_ptr, &i_ptr);
       codelen = c_ptr - codebuff;
       assert ( (codelen<128) && (codelen>0));
-      if (is->method->debug >3)
+      if (is->method->debug >7)
          logf(LOG_LOG,"isamd_appd: coded into %d: %s (nk=%d) (ix=%d)",
              codelen, hexdump(codebuff, codelen,hexbuff), 
              firstpp->numKeys,diffidx);
 
       if (diffidx + codelen > maxsize )
       { /* block full */
-         logf(LOG_LOG,"isamd_appd: block full (ix=%d mx=%d)",
-            diffidx, maxsize);
-         return 0;         /*!*/ /* do something about it!!! */
+         if (is->method->debug >3)
+            logf(LOG_LOG,"isamd_appd: block full (ix=%d mx=%d lix=%d)",
+               diffidx, maxsize, difflenidx);
+         if (is->method->debug >8)
+            logf(LOG_LOG,"isamd_appd: block pp=%p buf=%p [%d]:%s",
+               pp, pp->buf, 
+               difflenidx, hexdump(&pp->buf[difflenidx],8,0));
+         if (mergecount++)
+             ++(is->files[0].no_remerges);
+         merge_rc = merge (&firstpp, &pp, &i_key);
+         if (0!=merge_rc)
+           return merge_rc;  /* merge handled them all ! */
+
+         /* set things up so we can continue */
+         pp = read_diff_block(firstpp, &diffidx);
+         (*is->method->code_reset)(encoder_data);
+         maxsize = is->method->filecat[pp->cat].bsize; 
+         difflenidx=diffidx;
+         diffidx+=sizeof(int);
+
+         /* code the current input key again */
+         c_ptr=codebuff;
+         i_ptr=i_item;
+         (*is->method->code_item)(ISAMD_ENCODE, encoder_data, &c_ptr, &i_ptr);
+         codelen = c_ptr - codebuff;
+         assert ( (codelen<128) && (codelen>0));
+         if (is->method->debug >7)
+            logf(LOG_LOG,"isamd_appd: recoded into %d: %s (nk=%d) (ix=%d)",
+                codelen, hexdump(codebuff, codelen,hexbuff), 
+                firstpp->numKeys,diffidx);
+          
       } /* block full */
       
+      /* Note: this goes horribly wrong if there is no room for the diff */
+      /* after the merge! The solution is to increase the limit in */
+      /* separateDiffBlock, to force a separate diff block earlier, and not */
+      /* to have absurdly small blocks */
+      assert ( diffidx+codelen <= maxsize );
+      
       /* save the diff */ 
       memcpy(&(pp->buf[diffidx]),codebuff,codelen);
       diffidx += codelen;
@@ -533,16 +940,18 @@ static int append_diffs(ISAMD is, ISAMD_P ipos, ISAMD_I data)
         firstpp->numKeys++; /* insert diff */
       else
         firstpp->numKeys--; /* delete diff */ 
+
+      /* update length of this diff run */
       memcpy(&(pp->buf[difflenidx]),&diffidx,sizeof(diffidx));
       if (firstpp==pp)
         firstpp->diffs =diffidx*2+0;
       else
         pp->size =diffidx;
       
-      /* try to read the next input */
+      /* (try to) read the next input */
       i_ptr = i_item;
       i_more = (*data->read_item)(data->clientData, &i_ptr, &i_mode); 
-      if ( (i_more) && (is->method->debug >3) )
+      if ( (i_more) && (is->method->debug >6) )
          logf(LOG_LOG,"isamd_appd: got m=%d %s",
             i_mode, hexdump(i_item,i_ptr-i_item,hexbuff) );
    } /* more loop */
@@ -551,26 +960,19 @@ static int append_diffs(ISAMD is, ISAMD_P ipos, ISAMD_I data)
    difflenidx = diffidx;
    while ( (difflenidx-diffidx<=sizeof(int)) && (difflenidx<maxsize))
      pp->buf[difflenidx++]='\0';
-   
-   /* ok, save the block(s) */
-   if (firstpp != pp) 
-   { /* save the diff block */
-      pp->next = 0;  /* just to be sure */
-      isamd_buildlaterblock(pp);
-      isamd_write_block(is,pp->cat,pp->pos,pp->buf);
-      isamd_pp_close(pp);
-   }
 
-   isamd_buildfirstblock(firstpp);
-   isamd_write_block(is,firstpp->cat,firstpp->pos,firstpp->buf);   
-   retval = isamd_addr(firstpp->pos,firstpp->cat);
-   isamd_pp_close(firstpp);
 
-   return retval;
+  (*firstpp->is->method->code_stop)(ISAMD_ENCODE, encoder_data);
+   return save_both_pps( firstpp, pp );
+
 } /* append_diffs */
 
 
 
+/*************************************************************
+ * isamd_append itself, Sweet, isn't it
+ *************************************************************/
+
 ISAMD_P isamd_append (ISAMD is, ISAMD_P ipos, ISAMD_I data)
 {
    int retval=0;
@@ -584,11 +986,762 @@ ISAMD_P isamd_append (ISAMD is, ISAMD_P ipos, ISAMD_I data)
 } /*  isamd_append */
 
 
-/*
- * $Log: merge-d.c,v $
- * Revision 1.3  1999-07-21 14:24:50  heikki
- * isamd write and read functions ok, except when diff block full.
- * (merge not yet done)
+
+#else /* NEW_ISAM_D */
+/***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************
+ ***************************************************************/
+
+
+/***************************************************************
+ * General support routines
+ ***************************************************************/
+
+static void isamd_reduceblock(ISAMD_PP pp)
+/* takes a large block, and reduces its category if possible */
+/* Presumably the first block in an isam-list */
+{
+   if (pp->pos)
+      return; /* existing block, do not touch */
+      /* TODO: Probably we may touch anyway? */
+   if (pp->is->method->debug > 5)  
+     logf(LOG_LOG,"isamd_reduce: start p=%d c=%d sz=%d",
+       pp->pos, pp->cat, pp->size); 
+   while ( ( pp->cat > 0 ) && (!pp->next) && 
+           (pp->offset < pp->is->method->filecat[pp->cat-1].bsize ) )
+      pp->cat--;
+   pp->pos = isamd_alloc_block(pp->is, pp->cat);
+   if (pp->is->method->debug > 5) 
+     logf(LOG_LOG,"isamd_reduce:  got  p=%d c=%d sz=%d",
+       pp->pos, pp->cat, pp->size);    
+} /* reduceblock */
+
+
+static int save_first_pp ( ISAMD_PP firstpp)
+{
+   isamd_buildfirstblock(firstpp);
+   isamd_write_block(firstpp->is,firstpp->cat,firstpp->pos,firstpp->buf);
+   return isamd_addr(firstpp->pos,firstpp->cat);
+}
+
+static void save_last_pp (ISAMD_PP pp)
+{
+   pp->next = 0;/* just to be sure */
+   isamd_buildlaterblock(pp);
+   isamd_write_block(pp->is,pp->cat,pp->pos,pp->buf);
+}
+
+#ifdef UNUSED
+static int save_both_pps (ISAMD_PP firstpp, ISAMD_PP pp)
+{
+   /* order of things: Better to save firstpp first, if there are just two */
+   /* blocks, but last if there are blocks in between, as these have already */
+   /* been saved... optimise later (that's why this is in its own func...*/
+   int retval = save_first_pp(firstpp);
+   if (firstpp!=pp){ 
+      save_last_pp(pp);
+      isamd_pp_close(pp);
+   }
+   isamd_pp_close(firstpp);
+   return retval;
+} /* save_both_pps */
+#endif
+
+
+
+/***************************************************************
+ * Diffblock handling
+ ***************************************************************/
+
+void isamd_free_diffs(ISAMD_PP pp)
+{
+  int i;
+  if (pp->is->method->debug > 5)
+     logf(LOG_LOG,"isamd_free_diffs: pp=%p di=%p", pp, pp->diffinfo);
+  if (!pp->diffinfo) 
+    return;
+  for (i=1;pp->diffinfo[i].decodeData;i++) 
+  {
+      if (pp->is->method->debug > 8)
+         logf(LOG_LOG,"isamd_free_diffs [%d]=%p",i, 
+                       pp->diffinfo[i].decodeData);
+      (*pp->is->method->code_stop)(ISAMD_DECODE,pp->diffinfo[i].decodeData);
+  } 
+  xfree(pp->diffinfo);
+  if (pp->diffbuf != pp->buf)
+    xfree (pp->diffbuf);  
+  pp->diffbuf=0;
+  pp->diffinfo=0;
+} /* isamd_free_diffs */
+
+
+static void getDiffInfo(ISAMD_PP pp, int diffidx)
+{ /* builds the diff info structures from a diffblock */
+   int maxinfos = pp->is->method->filecat[pp->cat].bsize / 5 +1;
+    /* Each diff takes at least 5 bytes. Probably more, but this is safe */
+   int i=2;  /* [0] is used for the main data, [1] for merge inputs */
+   int diffsz= maxinfos * sizeof(struct ISAMD_DIFF_s);
+
+   pp->diffinfo = xmalloc( diffsz ); 
+   memset(pp->diffinfo,'\0',diffsz);
+   if (pp->is->method->debug > 5)   
+      logf(LOG_LOG,"isamd_getDiffInfo: %d (%d:%d), ix=%d mx=%d",
+         isamd_addr(pp->pos, pp->cat), pp->cat, pp->pos, diffidx,maxinfos);
+   assert(pp->diffbuf);
+   
+   pp->diffinfo[0].maxidx=-1; /* mark as special */
+   pp->diffinfo[1].maxidx=-1; /* mark as special */
+
+   while (i<maxinfos) 
+   {  
+      if ( diffidx+sizeof(int) > pp->is->method->filecat[pp->cat].bsize )
+      {
+         if (pp->is->method->debug > 5)
+           logf(LOG_LOG,"isamd_getDiffInfo:Near end (no room for len) at ix=%d n=%d",
+               diffidx, i);
+         return; /* whole block done */
+      }
+      memcpy( &pp->diffinfo[i].maxidx, &pp->diffbuf[diffidx], sizeof(int) );
+
+      if (pp->is->method->debug > 5)
+        logf(LOG_LOG,"isamd_getDiffInfo: max=%d ix=%d dbuf=%p",
+          pp->diffinfo[i].maxidx, diffidx, pp->diffbuf);
+
+      if ( (pp->is->method->debug > 0) &&
+         (pp->diffinfo[i].maxidx > pp->is->method->filecat[pp->cat].bsize) )
+      { /* bug-hunting, this fails on some long runs that log too much */
+         logf(LOG_LOG,"Bad MaxIx!!! %s:%d: diffidx=%d", 
+                       __FILE__,__LINE__, diffidx);
+         logf(LOG_LOG,"i=%d maxix=%d bsz=%d", i, pp->diffinfo[i].maxidx,
+                       pp->is->method->filecat[pp->cat].bsize);
+         logf(LOG_LOG,"pp=%d=%d:%d  pp->nx=%d=%d:%d",
+                       isamd_addr(pp->pos,pp->cat), pp->pos, pp->cat,
+                       pp->next, isamd_type(pp->next), isamd_block(pp->next) );                      
+      }
+      assert(pp->diffinfo[i].maxidx <= pp->is->method->filecat[pp->cat].bsize+1);
+
+      if (0==pp->diffinfo[i].maxidx)
+      {
+         if (pp->is->method->debug > 5)  //!!! 4
+           logf(LOG_LOG,"isamd_getDiffInfo:End mark at ix=%d n=%d",
+               diffidx, i);
+         return; /* end marker */
+      }
+      diffidx += sizeof(int);
+      pp->diffinfo[i].decodeData = (*pp->is->method->code_start)(ISAMD_DECODE);
+      pp->diffinfo[i].diffidx = diffidx;
+      if (pp->is->method->debug > 5)
+        logf(LOG_LOG,"isamd_getDiff[%d]:%d-%d %s",
+          i,diffidx-sizeof(int),pp->diffinfo[i].maxidx,
+          hexdump((char *)&pp->diffbuf[diffidx-4],8,0) );
+      diffidx=pp->diffinfo[i].maxidx;
+      if ( diffidx > pp->is->method->filecat[pp->cat].bsize )
+        return; /* whole block done */
+      ++i;
+   }
+   assert (!"too many diff sequences in the block");
+}
+
+/***************************************************************
+ * Main block operations
+ ***************************************************************/
+
+
+static ISAMD_PP get_new_main_block( ISAMD_PP firstpp, ISAMD_PP pp)
+{  /* allocates a new block for the main data, and links it in */
+  int newblock;
+  if (0 == firstpp->next) 
+  {  /* special case, pp not yet allocated. */
+     /*Started as largest size, that's fine */
+     pp->pos = isamd_alloc_block(pp->is,pp->cat);
+     firstpp->next = isamd_addr(pp->pos,pp->cat);
+     if (pp->is->method->debug >3) 
+        logf(LOG_LOG,"isamd_build: Alloc 1. dblock  p=%d=%d:%d",
+           isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos);
+  }
+  newblock=isamd_alloc_block(pp->is,pp->cat);
+  pp->next=isamd_addr(pp->cat,newblock);
+  isamd_buildlaterblock(pp);
+  isamd_write_block(pp->is,pp->cat,pp->pos,pp->buf);
+  if (pp->is->method->debug >3) 
+     logf(LOG_LOG,"isamd_build: Alloc nxt %d=%d:%d -> %d=%d:%d",
+        isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos,
+        isamd_addr(newblock,pp->cat), pp->cat, newblock);
+  pp->next=0;
+  pp->pos=newblock;
+  pp->size=pp->offset=ISAMD_BLOCK_OFFSET_N;  
+  return pp;
+} /* get_new_main_block */
+
+
+static ISAMD_PP  append_main_item(ISAMD_PP firstpp, 
+                                  ISAMD_PP pp, 
+                                  struct it_key *i_key)
+{  /* appends one item in the main data block, allocates new if needed */
+   char *i_item= (char *) i_key;  /* same as char */
+   char *i_ptr=i_item;
+   char codebuff[128];
+   char *c_ptr = codebuff;
+   int codelen;
+   char hexbuff[64];
+
+   int maxsize = pp->is->method->filecat[pp->is->max_cat].bsize; 
+
+   c_ptr=codebuff;
+   i_ptr=i_item;
+   (*pp->is->method->code_item)(ISAMD_ENCODE, pp->decodeClientData,
+                                &c_ptr, &i_ptr);
+   codelen = c_ptr - codebuff;
+   assert ( (codelen<128) && (codelen>0));
+   if (pp->is->method->debug >7)
+      logf(LOG_LOG,"isamd:build: coded into %s  (nk=%d)",
+          hexdump(codebuff, c_ptr-codebuff,hexbuff), firstpp->numKeys+1);
+
+   if (pp->offset + codelen > maxsize )
+   { /* oops, block full - get a new one */
+      pp =  get_new_main_block( firstpp, pp );
+      /* reset encoging and code again */
+      (*pp->is->method->code_reset)(pp->decodeClientData);
+      c_ptr=codebuff;
+      i_ptr=i_item;
+      (*pp->is->method->code_item)(ISAMD_ENCODE, pp->decodeClientData, 
+                                   &c_ptr, &i_ptr);
+      codelen = c_ptr - codebuff;
+      assert ( (codelen<128) && (codelen>0));
+      if (pp->is->method->debug >7)
+         logf(LOG_LOG,"isamd:build: recoded into %s  (nk=%d)",
+             hexdump(codebuff, c_ptr-codebuff,hexbuff), firstpp->numKeys+1);
+   } /* block full */    
+
+   assert (pp->offset + codelen <= maxsize );
+   
+   /* write the data into pp, now we must have room */ 
+   memcpy(&(pp->buf[pp->offset]),codebuff,codelen);
+   pp->offset += codelen;
+   pp->size += codelen;
+   firstpp->numKeys++;
+   /* clear the next 4 bytes in block, to avoid confusions with diff lens */
+   /* dirty, it should not be done here, but something slips somewhere, and */
+   /* I hope this fixes it...  - Heikki */
+   codelen = pp->offset;
+   while ( (codelen < maxsize ) && (codelen <= pp->offset+4) )
+     pp->buf[codelen++] = '\0';
+   return pp;    
+} /* append_main_item */
+
+
+/***************************************************************
+ * Merge
+ ***************************************************************/
+
+static int merge ( ISAMD_PP firstpp,      /* first pp (with diffs) */
+                   struct it_key *p_key,  /* the data item that didn't fit*/
+                   ISAMD_I data)          /* more input data comes here */
+{
+  int diffidx;  
+  int killblk=0;
+  struct it_key r_key;
+  char * r_ptr;
+  int r_more = 1;
+  ISAMD_PP pp;
+  ISAMD_PP readpp=firstpp;
+  int retval=0;
+  int diffcat = firstpp->cat;  /* keep the category of the diffblock even */
+                               /* if it is going to be empty now. */
+                               /* Alternative: Make it the minimal, and */
+                               /* resize later. Saves disk, but will lead */
+                               /* into bad seeks. */
+  
+  ++(readpp->is->files[0].no_merges);
+     
+  /* set up diffs as they should be for reading */
+  diffidx = ISAMD_BLOCK_OFFSET_1; 
+  readpp->diffbuf=readpp->buf;
+  getDiffInfo(readpp,diffidx);
+  
+  if (readpp->is->method->debug >4) 
+      logf(LOG_LOG,"isamd_merge: f=%d=%d:%d n=%d=%d:%d",
+        isamd_addr(firstpp->pos,firstpp->cat), firstpp->cat, firstpp->pos,
+        firstpp->next, isamd_type(firstpp->next), isamd_block(firstpp->next));  
+
+  /* release our data block. Do before reading, when pos is stable ! */
+  killblk=firstpp->pos;
+  if (killblk)
+  {
+      isamd_release_block(firstpp->is, firstpp->cat, killblk);
+      if (readpp->is->method->debug >3)   
+          logf(LOG_LOG,"isamd_merge: released old firstblock %d (%d:%d)",
+              isamd_addr(killblk,firstpp->cat), firstpp->cat, killblk );
+  }
+  
+  /* force the read to reload the first data block at first try */
+  readpp->offset=readpp->size+1;
+
+
+  r_ptr= (char *) &r_key;
+  r_more = isamd_read_item( readpp, &r_ptr);
+  if (!r_more)  
+  { /* oops, all data has been deleted! what to do??? */
+    /* never mind, we have at least one more delta to add to the block */
+    /* pray that is not a delete as well... */
+    r_key.sysno = 0;
+    r_key.seqno = 0;
+     if (readpp->is->method->debug >5) 
+         logf(LOG_LOG,"isamd_merge:all data has been deleted (nk=%d) ",
+            readpp->numKeys);
+    //assert (readpp->numKeys == 0);  /* no longer true! */
+  }
+
+
+  /* set up the new blocks for simple writing */
+  firstpp=isamd_pp_open(readpp->is,isamd_addr(0, diffcat));
+  firstpp->pos=isamd_alloc_block(firstpp->is,diffcat);
+  
+  pp=isamd_pp_open(readpp->is,isamd_addr(0,readpp->is->max_cat) );
+  
+  while (r_more)
+  {
+     if (readpp->is->method->debug >6) 
+         logf(LOG_LOG,"isamd_merge: got key %d.%d",
+           r_key.sysno, r_key.seqno );
+     pp= append_main_item(firstpp, pp, &r_key);
+
+     if ( (readpp->pos != killblk ) && (0!=readpp->pos) )
+     {  /* pos can get to 0 at end of main seq, if still diffs left...*/
+        if (readpp->is->method->debug >3)  
+            logf(LOG_LOG,"isamd_merge: released block %d (%d:%d) now %d=%d:%d",
+                isamd_addr(killblk,readpp->cat), readpp->cat, killblk,
+                isamd_addr(readpp->pos,readpp->cat),readpp->cat, readpp->pos );
+        isamd_release_block(readpp->is, readpp->cat, readpp->pos);
+        killblk=readpp->pos;
+     }
+
+     /* (try to) read next item */
+     r_ptr= (char *) &r_key;
+     r_more = isamd_read_item( readpp, &r_ptr);
+
+  } /* while read */
+  
+  
+  firstpp->diffs=0; 
+
+
+  isamd_reduceblock(pp);  /* reduce size if possible */
+  save_last_pp(pp);
+  if (readpp->is->method->debug >4) 
+      logf(LOG_LOG,"isamd_merge: saved last block %d=%d:%d",
+            isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos);
+  isamd_pp_close(pp);
+
+  if (readpp->is->method->debug >5) 
+        logf(LOG_LOG,"isamd_merge: closing readpp %d=%d:%d di=%p",
+              isamd_addr(readpp->pos,readpp->cat), readpp->cat, readpp->pos,
+              readpp->diffinfo);
+  isamd_pp_close(readpp); /* pos is 0 by now, at eof. close works anyway */
+
+  if (readpp->is->method->debug >2)  
+      logf(LOG_LOG,"isamd_merge: merge ret f=%d=%d:%d pp=%d=%d:%d",
+            isamd_addr(firstpp->pos,pp->cat), firstpp->cat, firstpp->pos,
+            isamd_addr(pp->pos,pp->cat), pp->cat, pp->pos);
+
+  retval = isamd_addr(firstpp->pos, firstpp->cat);
+  isamd_pp_close(firstpp);
+
+  return retval; 
+  
+} /* merge */
+
+
+
+
+/***************************************************************
+ * Read with merge
+ ***************************************************************/
+
+/* Reads one item and corrects for the diffs, if any */
+/* return 1 for ok, 0 for eof */
+int isamd_read_item_merge (
+                     ISAMD_PP pp, 
+                     char **dst,
+                     struct it_key *p_key,  /* the data item that didn't fit*/
+                     ISAMD_I data)          /* more input data comes here */
+{                    /* The last two args can be null for ordinary reads */
+  char *keyptr;
+  char *codeptr;
+  char *codestart;
+  int winner=0; /* which diff holds the day */
+  int i; /* looping diffs */
+  int cmp;
+  int retry=1;
+  if (pp->diffs==0)  /* no diffs, just read the thing */
+     return isamd_read_main_item(pp,dst);
+
+  if (!pp->diffinfo)
+    getDiffInfo(pp, pp->offset);
+
+  if (p_key)  
+    pp->diffinfo[1].key = *p_key;  /* the key merge could not handle */
+  else
+    pp->diffinfo[1].key.sysno=0;
+
+  if (data)
+    pp->diffinfo[1].maxidx=-1;  /* signal we have diffs to read */
+  else
+    pp->diffinfo[1].maxidx=0;
+  pp->size=pp->offset=pp->is->method->filecat[pp->cat].bsize; 
+     /* this forces a read of the next block at first read */
+        
+  while (retry)
+
+  {
+     retry=0;
+     if (0==pp->diffinfo[0].key.sysno) 
+     { /* 0 is special case, main data. */
+        keyptr=(char*) &(pp->diffinfo[0].key);
+        pp->diffinfo[0].mode = ! isamd_read_main_item(pp,&keyptr);
+        if (pp->is->method->debug > 7)
+          logf(LOG_LOG,"isamd_read_item: read main %d.%d (%x.%x)",
+            pp->diffinfo[0].key.sysno, pp->diffinfo[0].key.seqno,
+            pp->diffinfo[0].key.sysno, pp->diffinfo[0].key.seqno);
+     } /* get main data */
+     
+     if ( (0==pp->diffinfo[1].key.sysno) && (-1==pp->diffinfo[1].maxidx) );
+     { /* 1 is another special case, the input data at merge */
+        keyptr = (char *) &pp->diffinfo[1].key;
+        i = (*data->read_item)(data->clientData, &keyptr, &pp->diffinfo[1].mode); 
+        if (!i) 
+        {  /* did not get it */
+           pp->diffinfo[1].key.sysno=0;
+           pp->diffinfo[1].maxidx=-2; /* stop trying */
+        }
+        if (pp->is->method->debug >6)
+           logf(LOG_LOG,"merge: read diff m=%d %d.%d (%x.%x)",
+              pp->diffinfo[1].mode, 
+              pp->diffinfo[1].key.sysno, pp->diffinfo[1].key.seqno,
+              pp->diffinfo[1].key.sysno, pp->diffinfo[1].key.seqno );        
+     } /* get input data */
+     
+     winner = 0;
+     for (i=1; (!retry) && (pp->diffinfo[i].decodeData); i++)
+     {
+        if (pp->is->method->debug > 8)
+          logf(LOG_LOG,"isamd_read_item: considering d%d %d.%d ix=%d mx=%d",
+               i, pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
+                  pp->diffinfo[i].diffidx,   pp->diffinfo[i].maxidx);
+            
+        if ( (0==pp->diffinfo[i].key.sysno) &&
+             (pp->diffinfo[i].diffidx < pp->diffinfo[i].maxidx))
+        {/* read a new one, if possible */
+           codeptr= codestart = &(pp->diffbuf[pp->diffinfo[i].diffidx]);
+           keyptr=(char *)&(pp->diffinfo[i].key);
+           (*pp->is->method->code_item)(ISAMD_DECODE,
+                 pp->diffinfo[i].decodeData, &keyptr, &codeptr);
+           pp->diffinfo[i].diffidx += codeptr-codestart;
+           pp->diffinfo[i].mode = pp->diffinfo[i].key.seqno & 1;
+           pp->diffinfo[i].key.seqno = pp->diffinfo[i].key.seqno >>1 ;
+           if (pp->is->method->debug > 7)
+             logf(LOG_LOG,"isamd_read_item: read diff[%d] %d.%d (%x.%x)",i,
+               pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
+               pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno);
+        } 
+        if ( 0!= pp->diffinfo[i].key.sysno)
+        { /* got a key, compare */
+          cmp=key_compare(&pp->diffinfo[i].key, &pp->diffinfo[winner].key);
+          if (0==pp->diffinfo[winner].key.sysno)
+            cmp=-1; /* end of main sequence, take all diffs */
+          if (cmp<0)
+          {
+             if (pp->is->method->debug > 8)
+               logf(LOG_LOG,"isamd_read_item: ins %d<%d %d.%d (%x.%x) < %d.%d (%x.%x)",
+                 i, winner,
+                 pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
+                 pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
+                 pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno,
+                 pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno);
+             if (pp->diffinfo[i].mode)  /* insert diff, should always be */
+               winner = i;
+             else
+               assert(!"delete diff for nonexisting item");  
+               /* is an assert too steep here? Not really.*/
+          } /* earlier key */
+          else if (cmp==0)
+          {
+             if (!pp->diffinfo[i].mode) /* delete diff. should always be */
+             {
+                if (pp->is->method->debug > 8)
+                  logf(LOG_LOG,"isamd_read_item: del %d at%d %d.%d (%x.%x)",
+                    i, winner,
+                    pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
+                    pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno);
+                pp->diffinfo[winner].key.sysno=0; /* delete it */
+             }
+             else
+                if (pp->is->method->debug > 2)
+                  logf(LOG_LOG,"isamd_read_item: duplicate ins %d at%d %d.%d (%x.%x)",
+                    i, winner,
+                    pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno,
+                    pp->diffinfo[i].key.sysno, pp->diffinfo[i].key.seqno);
+                /* skip the insert, since we already have it in the base */
+                /* Should we fail an assertion here??? */
+             pp->diffinfo[i].key.sysno=0; /* done with the delete */
+             retry=1; /* start all over again */
+          } /* matching key */
+          /* else it is a later key, its turn will come */
+        } /* got a key */
+     } /* for each diff */
+  } /* not retry */
+
+  if ( pp->diffinfo[winner].key.sysno)
+  {
+    if (pp->is->method->debug > 7)
+      logf(LOG_LOG,"isamd_read_item: got %d  %d.%d (%x.%x)",
+        winner,
+        pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno,
+        pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno);
+    memcpy(*dst, &pp->diffinfo[winner].key, sizeof(struct it_key) );
+    *dst += sizeof(struct it_key);
+    pp->diffinfo[winner].key.sysno=0; /* used that one up */
+    cmp= 1;
+  } 
+  else 
+  {
+    if (pp->is->method->debug > 7)
+      logf(LOG_LOG,"isamd_read_item: eof w=%d  %d.%d (%x.%x)",
+        winner,
+        pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno,
+        pp->diffinfo[winner].key.sysno, pp->diffinfo[winner].key.seqno);
+    assert(winner==0); /* if nothing found, nothing comes from a diff */
+    cmp= 0; /* eof */
+  }
+  return cmp;
+   
+} /* isamd_read_item */
+
+
+int isamd_read_item (ISAMD_PP pp, char **dst)
+{
+  return isamd_read_item_merge(pp,dst,0,0);
+}
+
+
+/***************************************************************
+ * Appending diffs 
+ ***************************************************************/
+
+
+
+static int append_diffs(ISAMD is, ISAMD_P ipos, ISAMD_I data)
+{
+   struct it_key i_key;    /* one input item */
+   char *i_item = (char *) &i_key;  /* same as chars */
+   char *i_ptr=i_item;
+   int i_more =1;
+   int i_mode;     /* 0 for delete, 1 for insert */ 
+
+   ISAMD_PP firstpp;
+   char hexbuff[64];
+   int diffidx=0;
+   int maxsize=0;
+   int difflenidx;
+   char codebuff[128];
+   char *c_ptr = codebuff;
+   int codelen;
+   int merge_rc;
+   int retval=0;
+
+   if (0==ipos)
+   {
+       firstpp=isamd_pp_open(is, isamd_addr(0,0) );
+       firstpp->size=firstpp->offset=ISAMD_BLOCK_OFFSET_1;
+         /* create in smallest category, will expand later */
+       ++(is->files[0].no_fbuilds);
+   } 
+   else
+   {
+       firstpp=isamd_pp_open(is, ipos);
+       ++(is->files[0].no_appds);
+   }
+
+   if (is->method->debug >2) 
+      logf(LOG_LOG,"isamd_appd: Start ipos=%d=%d:%d n=%d=%d:%d nk=%d",
+        ipos, isamd_type(ipos), isamd_block(ipos),
+        firstpp->next, isamd_type(firstpp->next), isamd_block(firstpp->diffs),
+        firstpp->numKeys);
+   maxsize = is->method->filecat[firstpp->cat].bsize; 
+   
+   difflenidx = diffidx = firstpp->size;
+   
+   diffidx+=sizeof(int);  /* difflen will be stored here */
+   
+   /* read first input */
+   i_ptr = i_item;
+   i_more = (*data->read_item)(data->clientData, &i_ptr, &i_mode); 
+
+   if (is->method->debug >6)
+      logf(LOG_LOG,"isamd_appd: start with m=%d %s",
+         i_mode, hexdump(i_item,i_ptr-i_item,hexbuff) );
+
+   while (i_more)
+   {     
+      /* store the mode bit inside key */
+      assert( ((i_key.seqno<<1)>>1) == i_key.seqno); /* can spare the bit */
+      i_key.seqno = i_key.seqno * 2 + i_mode;  
+
+      c_ptr=codebuff;
+      i_ptr=i_item;
+      (*is->method->code_item)(ISAMD_ENCODE, firstpp->decodeClientData, 
+                               &c_ptr, &i_ptr);
+      codelen = c_ptr - codebuff;
+      assert ( (codelen<128) && (codelen>0));
+      if (is->method->debug >7)
+         logf(LOG_LOG,"isamd_appd: coded into %d: %s (nk=%d) (ix=%d)",
+             codelen, hexdump(codebuff, codelen,hexbuff), 
+             firstpp->numKeys,diffidx);
+
+      if (diffidx + codelen > maxsize )
+      { /* block full */
+         if (firstpp->cat < firstpp->is->max_cat)
+         { /* just increase the block size */
+             if (firstpp->pos > 0)  /* free the old block if allocated */
+                 isamd_release_block(is, firstpp->cat, firstpp->pos);
+             ++firstpp->cat;
+             maxsize = is->method->filecat[firstpp->cat].bsize; 
+             firstpp->pos=0; /* need to allocate it when saving */             
+             if (is->method->debug >3)
+                logf(LOG_LOG,"isamd_appd: increased diff block to %d (%d)",
+                   firstpp->cat, maxsize);
+         }
+         else 
+         { /* max size already - can't help, need to merge it */
+             merge_rc = merge (firstpp, &i_key, data);
+             if (0!=merge_rc)
+               return merge_rc;  /* merge handled them all ! */
+             assert(!"merge returned zero ??");
+         } /* need to merge */
+      } /* block full */
+      
+      assert ( diffidx+codelen <= maxsize );
+      
+      /* save the diff */ 
+      memcpy(&(firstpp->buf[diffidx]),codebuff,codelen);
+      diffidx += codelen;
+      firstpp->size += codelen;
+      firstpp->offset +=codelen;
+      
+      if (i_mode)
+        firstpp->numKeys++; /* insert diff */
+      else
+        firstpp->numKeys--; /* delete diff */ 
+
+      /* update length of this diff run */
+      memcpy(&(firstpp->buf[difflenidx]),&diffidx,sizeof(diffidx));
+      
+      /* (try to) read the next input */
+      i_ptr = i_item;
+      i_more = (*data->read_item)(data->clientData, &i_ptr, &i_mode); 
+      if ( (i_more) && (is->method->debug >6) )
+         logf(LOG_LOG,"isamd_appd: got m=%d %s",
+            i_mode, hexdump(i_item,i_ptr-i_item,hexbuff) );
+   } /* more loop */
+
+   /* clear the next difflen, if room for such */
+   difflenidx = diffidx;
+   while ( (difflenidx-diffidx<=sizeof(int)) && (difflenidx<maxsize))
+     firstpp->buf[difflenidx++]='\0';
+
+   if (0==firstpp->pos)  /* need to (re)alloc the block */
+      firstpp->pos = isamd_alloc_block(is, firstpp->cat);
+
+   retval = save_first_pp( firstpp );
+   isamd_pp_close(firstpp);
+    
+   return retval;
+} /* append_diffs */
+
+
+
+
+/*************************************************************
+ * isamd_append itself, Sweet, isn't it
+ *************************************************************/
+
+ISAMD_P isamd_append (ISAMD is, ISAMD_P ipos, ISAMD_I data)
+{
+   return append_diffs(is,ipos,data);
+} /*  isamd_append */
+
+
+
+
+
+#endif /* NEW_ISAM_D */
+
+
+
+/*
+ * $Log: merge-d.c,v $
+ * Revision 1.18  1999-08-25 18:09:24  heikki
+ * Starting to optimize
+ *
+ * Revision 1.17  1999/08/24 13:17:42  heikki
+ * Block sizes, comments
+ *
+ * Revision 1.16  1999/08/24 10:12:02  heikki
+ * Comments about optimising
+ *
+ * Revision 1.15  1999/08/22 08:26:34  heikki
+ * COmments
+ *
+ * Revision 1.14  1999/08/20 12:25:58  heikki
+ * Statistics in isamd
+ *
+ * Revision 1.13  1999/08/18 13:59:19  heikki
+ * Fixed another unlikely difflen bug
+ *
+ * Revision 1.12  1999/08/18 13:28:17  heikki
+ * Set log levels to decent values
+ *
+ * Revision 1.11  1999/08/18 10:37:11  heikki
+ * Fixed (another) difflen bug
+ *
+ * Revision 1.10  1999/08/18 09:13:31  heikki
+ * Fixed a detail
+ *
+ * Revision 1.9  1999/08/17 19:46:53  heikki
+ * Fixed a memory leak
+ *
+ * Revision 1.8  1999/08/07 11:30:59  heikki
+ * Bug fixing (still a mem leak somewhere)
+ *
+ * Revision 1.7  1999/08/04 14:21:18  heikki
+ * isam-d seems to be working.
+ *
+ * Revision 1.6  1999/07/23 15:43:05  heikki
+ * Hunted a few bugs in isam-d. Still crashes on the long test run
+ *
+ * Revision 1.5  1999/07/23 13:58:52  heikki
+ * merged closer to working, still fails on filling a separate, large block
+ *
+ * Revision 1.4  1999/07/21 14:53:55  heikki
+ * isamd read and write functions work, except when block full
+ * Merge missing still. Need to split some functions
  *
  * Revision 1.1  1999/07/14 13:14:47  heikki
  * Created empty