Add a size estimation mechanism to StoragePartitionHttpCacheDataRemover.

net/disk_cache/blockfile/backend_impl.cc

 // Copyright (c) 2012 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/blockfile/backend_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
@@ skipping 418 matching lines @@
       SyncEndEnumeration(iterator.Pass());
       return net::OK;
     }
 
     entry->DoomImpl();
     entry->Release();
     SyncEndEnumeration(iterator.Pass());  // The doom invalidated the iterator.
   }
 }
 
+int BackendImpl::SyncCalculateSizeOfEntriesBetween(
+    const base::Time initial_time, const base::Time end_time) {
+  DCHECK_NE(net::APP_CACHE, cache_type_);
+  DCHECK_GE(end_time, initial_time);

[Deprecated (see juliatuttle), 2015/09/08 17:44:40]

Does this work even if one or both of initial and end time are null, which is
allowed as an open-ended interval? (I believe null is represented as 0, and
therefore a finite initial time with no end time might trip this DCHECK?)

[msramek, 2015/09/08 18:32:22]

If you look at BackendImpl::SyncDoomEntriesBetween, the same check is on line
382 above. Furthermore, according to lines 397 and 398, deletion with two 0
parameters never worked.

(where by 0 I mean uninitialized base::Time() = 1st January 1601; it's not
actually NULL, because these are not pointers)

The current situation is that
1. BrowsingDataRemover uses [base::Time(), base::Time::Max()) to represent
unbounded interval

2. StorageHttpCacheDataRemover gets the interval from BrowsingDataRemover and
decides whether to use DoomAllEntries() or DoomEntriesBetween().

3. disk_cache should use DoomAllEntries() for unbounded interval. Less effective
DoomEntriesBetween(base::Time(), base::Time::Max()) also works. But
DoomEntriesBetween(base::Time(), base::Time()) doesn't.

+  if (disabled_)
+    return net::ERR_FAILED;
+
+  EntryImpl* node;
+  scoped_ptr<Rankings::Iterator> iterator(new Rankings::Iterator());
+  EntryImpl* next = OpenNextEntryImpl(iterator.get());
+  if (!next)
+    return net::OK;
+
+  int size = 0;
+  while (next) {
+    node = next;
+    next = OpenNextEntryImpl(iterator.get());
+
+    if (node->GetLastUsed() >= initial_time &&
+        node->GetLastUsed() < end_time) {
+      size += node->GetEntrySize();
+    } else if (node->GetLastUsed() < initial_time) {
+      if (next)
+        next->Release();
+      next = NULL;
+      SyncEndEnumeration(iterator.Pass());
+    }
+
+    node->Release();
+  }
+
+  return size;
+}
+
 int BackendImpl::SyncOpenNextEntry(Rankings::Iterator* iterator,
                                    Entry** next_entry) {
   *next_entry = OpenNextEntryImpl(iterator);
   return (*next_entry) ? net::OK : net::ERR_FAILED;
 }
 
 void BackendImpl::SyncEndEnumeration(scoped_ptr<Rankings::Iterator> iterator) {
   iterator->Reset();
 }
 
@@ skipping 798 matching lines @@
   return net::ERR_IO_PENDING;
 }
 
 int BackendImpl::DoomEntriesSince(const base::Time initial_time,
                                   const CompletionCallback& callback) {
   DCHECK(!callback.is_null());
   background_queue_.DoomEntriesSince(initial_time, callback);
   return net::ERR_IO_PENDING;
 }
 
+int BackendImpl::CalculateSizeOfEntriesBetween(
+    base::Time initial_time,
+    base::Time end_time,
+    const CompletionCallback& callback) {
+  DCHECK(!callback.is_null());
+  background_queue_.CalculateSizeOfEntriesBetween(
+      initial_time, end_time, callback);
+  return net::ERR_IO_PENDING;
+}
+
 class BackendImpl::IteratorImpl : public Backend::Iterator {
  public:
   explicit IteratorImpl(base::WeakPtr<InFlightBackendIO> background_queue)
       : background_queue_(background_queue),
         iterator_(new Rankings::Iterator()) {
   }
 
   ~IteratorImpl() override {
     if (background_queue_)
       background_queue_->EndEnumeration(iterator_.Pass());
@@ skipping 824 matching lines @@
     if (total_memory > kMaxBuffersSize || total_memory <= 0)
       total_memory = kMaxBuffersSize;
 
     done = true;
   }
 
   return static_cast<int>(total_memory);
 }
 
 }  // namespace disk_cache