Disk cache: Add support for having a sparse entry block that...

net/disk_cache/rankings.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/disk_cache/rankings.h"
 
 #include "base/histogram.h"
 #include "net/disk_cache/backend_impl.h"
 #include "net/disk_cache/entry_impl.h"
 #include "net/disk_cache/errors.h"
@@ skipping 376 matching lines @@
   UpdateIterators(&next);
   UpdateIterators(&prev);
 }
 
 // A crash in between Remove and Insert will lead to a dirty entry not on the
 // list. We want to avoid that case as much as we can (as while waiting for IO),
 // but the net effect is just an assert on debug when attempting to remove the
 // entry. Otherwise we'll need reentrant transactions, which is an overkill.
 void Rankings::UpdateRank(CacheRankingsBlock* node, bool modified, List list) {
   Time start = Time::Now();
+  NotAnIterator(node);
   Remove(node, list);
   Insert(node, modified, list);
   CACHE_UMA(AGE_MS, "UpdateRank", 0, start);
 }
 
 void Rankings::CompleteTransaction() {
   Addr node_addr(static_cast<CacheAddr>(control_data_->transaction));
   if (!node_addr.is_initialized() || node_addr.is_separate_file()) {
     NOTREACHED();
     LOG(ERROR) << "Invalid rankings info.";
@@ skipping 340 matching lines @@
   for (IteratorList::iterator it = iterators_.begin(); it != iterators_.end();
        ++it) {
     if (it->first == address) {
       CacheRankingsBlock* other = it->second;
       other->Data()->next = node->Data()->next;
       other->Data()->prev = node->Data()->prev;
     }
   }
 }
 
+void Rankings::NotAnIterator(CacheRankingsBlock* node) {
+#ifdef NDEBUG
+  // This method is only enabled for debug builds.
+  return;
+#endif
+  CacheAddr address = node->address().value();
+  for (IteratorList::iterator it = iterators_.begin(); it != iterators_.end();
+       ++it) {
+    if (it->first == address)
+      NOTREACHED();
+  }
+}
+
 void Rankings::IncrementCounter(List list) {
   if (!count_lists_)
     return;
 
   DCHECK(control_data_->sizes[list] < kint32max);
   if (control_data_->sizes[list] < kint32max)
     control_data_->sizes[list]++;
 }
 
 void Rankings::DecrementCounter(List list) {
   if (!count_lists_)
     return;
 
   DCHECK(control_data_->sizes[list] > 0);
   if (control_data_->sizes[list] > 0)
     control_data_->sizes[list]--;
 }
 
 }  // namespace disk_cache