Rev 3893: Restoring the debugging for now. in http://bzr.arbash-meinel.com/branches/bzr/brisbane/gc_delta_index_room

[John Arbash Meinel]

At http://bzr.arbash-meinel.com/branches/bzr/brisbane/gc_delta_index_room

------------------------------------------------------------
revno: 3893
revision-id: john at arbash-meinel.com-20090318220835-hfmreyshsh78l8pf
parent: john at arbash-meinel.com-20090318215056-dzx4j8ym5yhwh67b
committer: John Arbash Meinel <john at arbash-meinel.com>
branch nick: gc_delta_index_room
timestamp: Wed 2009-03-18 17:08:35 -0500
message:
  Restoring the debugging for now.
  Only matching commands that are > RABIN_WINDOW + 3 reduces the
  total number of resizes from 3.1k to 1.4k. Reduces overall
  matches from 9.6k => 9.1k. Those match commands were flooding
  the hash map, because they get repeated and always hit the same
  hash bucket.
  
  That said, this is seems overall slower than the old code, my
  guess is the O(MN) behavior of the resize loop. Time to put
  the new data into its own hash. :)
-------------- next part --------------
=== modified file 'bzrlib/diff-delta.c'
--- a/bzrlib/diff-delta.c	2009-03-18 21:50:56 +0000
+++ b/bzrlib/diff-delta.c	2009-03-18 22:08:35 +0000
@@ -252,9 +252,9 @@
 
     if (packed_entry - (struct index_entry *)mem
         != num_entries + hsize*EXTRA_NULLS) {
-        // fprintf(stderr, "We expected %d entries, but created %d\n",
-        //         num_entries + hsize*EXTRA_NULLS,
-        //         (int)(packed_entry - (struct index_entry*)mem));
+        fprintf(stderr, "We expected %d entries, but created %d\n",
+                num_entries + hsize*EXTRA_NULLS,
+                (int)(packed_entry - (struct index_entry*)mem));
     }
     assert(packed_entry - (struct index_entry *)mem
             == num_entries + hsize*EXTRA_NULLS);
@@ -543,9 +543,9 @@
         hsize = old_index->hash_mask + 1;
     }
     hmask = hsize - 1;
-    // fprintf(stderr, "resizing index to insert %d entries into array"
-    //                 " with %d entries: %x => %x\n",
-    //         num_entries, old_index->num_entries, old_index->hash_mask, hmask);
+    fprintf(stderr, "resizing index to insert %d entries into array"
+                    " with %d entries: %x => %x\n",
+            num_entries, old_index->num_entries, old_index->hash_mask, hmask);
 
     memsize = sizeof(*index)
         + sizeof(*packed_hash) * (hsize+1)
@@ -785,7 +785,13 @@
                 /* Invalid insert, not enough bytes in the delta */
                 break;
             }
-            for (; cmd > RABIN_WINDOW; cmd -= RABIN_WINDOW,
+            /* The create_delta code requires a match at least 4 characters
+             * (including only the last char of the RABIN_WINDOW) before it
+             * will consider it something worth copying rather than inserting.
+             * So we don't want to index anything that we know won't ever be a
+             * match.
+             */
+            for (; cmd > RABIN_WINDOW + 3; cmd -= RABIN_WINDOW,
                                        data += RABIN_WINDOW) {
                 unsigned int val = 0;
                 for (i = 1; i <= RABIN_WINDOW; i++)
@@ -849,18 +855,18 @@
         old_entry++;
         if (old_entry->ptr != NULL
             || old_entry >= old_index->hash[hash_offset + 1]) {
-            // char buff[128];
-            // get_text(buff, entry->ptr);
-            // fprintf(stderr, "Failed to find an opening @%x for %8x:\n '%s'\n",
-            //         hash_offset, entry->val, buff);
-            // for (old_entry = old_index->hash[hash_offset];
-            //      old_entry < old_index->hash[hash_offset+1];
-            //      ++old_entry) {
-            //     get_text(buff, old_entry->ptr);
-            //     fprintf(stderr, "  [%2d] %8x %8x: '%s'\n",
-            //             (int)(old_entry - old_index->hash[hash_offset]),
-            //             old_entry->val, old_entry->ptr, buff);
-            // }
+            char buff[128];
+            get_text(buff, entry->ptr);
+            fprintf(stderr, "Failed to find an opening @%x for %8x:\n '%s'\n",
+                    hash_offset, entry->val, buff);
+            for (old_entry = old_index->hash[hash_offset];
+                 old_entry < old_index->hash[hash_offset+1];
+                 ++old_entry) {
+                get_text(buff, old_entry->ptr);
+                fprintf(stderr, "  [%2d] %8x %8x: '%s'\n",
+                        (int)(old_entry - old_index->hash[hash_offset]),
+                        old_entry->val, old_entry->ptr, buff);
+            }
             break;
         }
         num_inserted++;
@@ -874,12 +880,12 @@
         /* We couldn't fit the new entries into the old index, so allocate a
          * new one, and fill it with stuff.
          */
-        // fprintf(stderr, "inserted %d before resize\n", num_inserted);
+        fprintf(stderr, "inserted %d before resize\n", num_inserted);
         new_index = create_index_from_old_and_new_entries(old_index,
             entry, num_entries);
     } else {
         new_index = NULL;
-        // fprintf(stderr, "inserted %d without resizing\n", num_inserted);
+        fprintf(stderr, "inserted %d without resizing\n", num_inserted);
     }
     free(entries);
     return new_index;