Ticket #455: bug-455-fix.patch

backends/chert/chert_cursor.cc

@@ -55 +55 @@
           is_after_end(false),
           tag_status(UNREAD),
           B(B_),
+          version(B_->cursor_version),
           level(B_->level)
 {
+    B->cursor_created_since_last_modification = true;
     C = new Cursor[level + 1];
 
     for (int j = 0; j < level; j++) {
@@ -67 +69 @@
     C[level].p = B->C[level].p;
 }
 
+void
+ChertCursor::resize()
+{
+    int new_level = B->level;
+    if (new_level <= level) {
+        for (int i = 0; i < new_level; i++) {
+            C[i].n = BLK_UNUSED;
+        }
+        for (int j = new_level; j < level; ++j) {
+            delete C[j].p;
+        }
+    } else {
+        Cursor * old_C = C;
+        C = new Cursor[new_level + 1];
+        for (int i = 0; i < level; i++) {
+            C[i].p = old_C[i].p;
+            C[i].n = BLK_UNUSED;
+        }
+        delete old_C;
+        for (int j = level; j < new_level; j++) {
+            C[j].p = new byte[B->block_size];
+            C[j].n = BLK_UNUSED;
+        }
+    }
+    level = new_level;
+    C[level].n = B->C[level].n;
+    C[level].p = B->C[level].p;
+    version = B->cursor_version;
+}
+
 ChertCursor::~ChertCursor()
 {
     // Use the value of level stored in the cursor rather than the
@@ -81 +113 @@
 ChertCursor::prev()
 {
     DEBUGCALL(DB, bool, "ChertCursor::prev", "");
-    Assert(B->level <= level);
     Assert(!is_after_end);
+    if (B->cursor_version != version) {
+        resize();
+        is_positioned = false;
+    }
 
     if (!is_positioned) {
         // We've read the last key and tag, and we're now not positioned.
@@ -126 +161 @@
 ChertCursor::next()
 {
     DEBUGCALL(DB, bool, "ChertCursor::next", "");
-    Assert(B->level <= level);
     Assert(!is_after_end);
+    if (B->cursor_version != version) {
+        resize();
+        (void)find_entry(current_key);
+    }
+
     if (tag_status == UNREAD) {
         while (true) {
             if (! B->next(C, 0)) {
@@ -157 +196 @@
 ChertCursor::find_entry(const string &key)
 {
     DEBUGCALL(DB, bool, "ChertCursor::find_entry", key);
-    Assert(B->level <= level);
+    if (B->cursor_version != version) {
+        resize();
+    }
 
     is_after_end = false;
 
@@ -203 +244 @@
 ChertCursor::find_entry_ge(const string &key)
 {
     DEBUGCALL(DB, bool, "ChertCursor::find_entry_ge", key);
-    Assert(B->level <= level);
+    if (B->cursor_version != version) {
+        resize();
+    }
 
     is_after_end = false;
 

backends/chert/chert_table.h

@@ -732 +732 @@
         /// Set to true when the database is opened to write.
         bool writable;
 
+        /// Flag for tracking when cursors need to rebuild.
+        mutable bool cursor_created_since_last_modification;
+
+        /// Version count for tracking when cursors need to rebuild.
+        unsigned long cursor_version;
+
         /* B-tree navigation functions */
         bool prev(Cursor *C_, int j) const {
             if (sequential) return prev_for_sequential(C_, j);

backends/chert/chert_cursor.h

@@ -72 +72 @@
         /// Assignment not allowed
         ChertCursor & operator=(const ChertCursor &);
 
+        void resize();
+
     protected:
         /** Whether the cursor is positioned at a valid entry.
          *
@@ -96 +98 @@
         /// Pointer to an array of Cursors
         Cursor * C;
 
+        unsigned long version;
+
         /** The value of level in the Btree structure. */
         int level;
 

backends/chert/chert_table.cc

@@ -1138 +1138 @@
     }
     if (!replacement) ++item_count;
     Btree_modified = true;
+    if (cursor_created_since_last_modification) {
+        cursor_created_since_last_modification = false;
+        ++cursor_version;
+    }
 }
 
 /* ChertTable::del(key) returns false if the key is not in the B-tree,
@@ -1175 +1179 @@
 
     item_count--;
     Btree_modified = true;
+    if (cursor_created_since_last_modification) {
+        cursor_created_since_last_modification = false;
+        ++cursor_version;
+    }
     RETURN(true);
 }
 
@@ -1579 +1587 @@
           Btree_modified(false),
           full_compaction(false),
           writable(!readonly_),
+          cursor_created_since_last_modification(false),
+          cursor_version(0),
           split_p(0),
           compress_strategy(compress_strategy_),
           deflate_zstream(NULL),