Disk cache: Add explicit support for eviction / deletion

of sparse entries.

I started to add code to modify the children_map of the
parent entry when a child is evicted but that ended up
being too much trouble for too little gain. We have to be
prepared to handle the case of not finding a child entry
because there is no way to make sure that the process
doesn't go away at any time, so adding a lot of complexity
just to avoid an extra entry lookup is just not worth it.

On the other hand, potentially freeing up a lot of space when
a sparse entry is deleted (insetad of just waiting for the
eviction code to do the cleanup) seems like a good thing.

BUG=12258
TEST=unittest

Review URL: http://codereview.chromium.org/149306

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20325 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 37 insertions, 0 deletions

diff --git a/net/disk_cache/entry_impl.cc b/net/disk_cache/entry_impl.cc
index 4c17cbb..75fb92e5 100644
--- a/net/disk_cache/entry_impl.cc
+++ b/net/disk_cache/entry_impl.cc
@@ -453,6 +453,11 @@ void EntryImpl::InternalDoom() {
 void EntryImpl::DeleteEntryData(bool everything) {
   DCHECK(doomed_ || !everything);
 
+  if (GetEntryFlags() & PARENT_ENTRY) {
+    // We have some child entries that must go away.
+    SparseControl::DeleteChildren(this);
+  }
+
   if (GetDataSize(0))
     CACHE_UMA(COUNTS, "DeleteHeader", 0, GetDataSize(0));
   if (GetDataSize(1))
@@ -834,6 +839,38 @@ int EntryImpl::InitSparseData() {
   return result;
 }
 
+void EntryImpl::SetEntryFlags(uint32 flags) {
+  entry_.Data()->flags |= flags;
+  entry_.set_modified();
+}
+
+uint32 EntryImpl::GetEntryFlags() {
+  return entry_.Data()->flags;
+}
+
+void EntryImpl::GetData(int index, char** buffer, Addr* address) {
+  if (user_buffers_[index].get()) {
+    // The data is already in memory, just copy it an we're done.
+    int data_len = entry_.Data()->data_size[index];
+    DCHECK(data_len <= kMaxBlockSize);
+    *buffer = new char[data_len];
+    memcpy(*buffer, user_buffers_[index].get(), data_len);
+    return;
+  }
+
+  // Bad news: we'd have to read the info from disk so instead we'll just tell
+  // the caller where to read from.
+  *buffer = NULL;
+  address->set_value(entry_.Data()->data_addr[index]);
+  if (address->is_initialized()) {
+    // Prevent us from deleting the block from the backing store.
+    backend_->ModifyStorageSize(entry_.Data()->data_size[index] -
+                                    unreported_size_[index], 0);
+    entry_.Data()->data_addr[index] = 0;
+    entry_.Data()->data_size[index] = 0;
+  }
+}
+
 void EntryImpl::ReportIOTime(Operation op, const base::Time& start) {
   int group = backend_->GetSizeGroup();
   switch (op) {