Add the IndexedDBActiveBlobRegistry, currently unused, to enable future blob

content/browser/indexed_db/indexed_db_active_blob_registry.cc

+// Copyright (c) 2013 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 "base/bind.h"
+#include "base/location.h"
+#include "base/task_runner.h"
+#include "content/browser/indexed_db/indexed_db_active_blob_registry.h"
+#include "content/browser/indexed_db/indexed_db_backing_store.h"
+#include "content/browser/indexed_db/indexed_db_factory.h"
+#include "content/browser/indexed_db/indexed_db_leveldb_coding.h"
+
+namespace content {
+
+IndexedDBActiveBlobRegistry::IndexedDBActiveBlobRegistry(
+    IndexedDBBackingStore* backing_store)
+    : backing_store_(backing_store), weak_factory_(this) {}
+
+IndexedDBActiveBlobRegistry::~IndexedDBActiveBlobRegistry() {
+  DCHECK(use_tracker_.empty());
+}
+
+void IndexedDBActiveBlobRegistry::AddBlobRef(int64 database_id,
+                                             int64 blob_key) {
+  DCHECK(backing_store_->task_runner()->RunsTasksOnCurrentThread());
+  DCHECK(KeyPrefix::IsValidDatabaseId(database_id));
+  DCHECK(DatabaseMetaDataKey::IsValidBlobKey(blob_key));
+  DCHECK(deleted_dbs_.end() == deleted_dbs_.find(database_id));

[jsbell, 2014/03/20 18:04:33]

Could use stl_util's ContainsKey()

[ericu, 2014/03/25 01:22:14]

Done.

+  bool need_ref = use_tracker_.empty();
+  SingleDBMap& single_db_map = use_tracker_[database_id];
+  SingleDBMap::iterator iter = single_db_map.find(blob_key);
+  if (iter == single_db_map.end()) {
+    single_db_map[blob_key] = false;
+    if (need_ref) {
+      backing_store_->factory()->ReportOutstandingBlobs(
+          backing_store_->origin_url(), true);
+    }
+  } else {
+    DCHECK(!need_ref);
+    DCHECK(!iter->second);  // You can't add a reference once it's been deleted.
+  }
+}
+
+void IndexedDBActiveBlobRegistry::ReleaseBlobRef(int64 database_id,
+                                                 int64 blob_key) {
+  DCHECK(backing_store_->task_runner()->RunsTasksOnCurrentThread());
+  DCHECK(KeyPrefix::IsValidDatabaseId(database_id));
+  DCHECK(DatabaseMetaDataKey::IsValidBlobKey(blob_key));
+  AllDBsMap::iterator db_pair = use_tracker_.find(database_id);
+  if (db_pair == use_tracker_.end()) {
+    NOTREACHED();
+    return;
+  }
+  SingleDBMap& single_db = db_pair->second;
+  SingleDBMap::iterator blob_pair = single_db.find(blob_key);
+  if (blob_pair == single_db.end()) {
+    NOTREACHED();
+    return;
+  }
+  bool delete_in_backend = false;
+  DeletedDBSet::iterator db_to_delete = deleted_dbs_.find(database_id);
+  bool db_marked_for_deletion = db_to_delete != deleted_dbs_.end();
+  // Don't bother deleting the file if we're going to delete its whole
+  // database directory soon.
+  delete_in_backend = blob_pair->second && !db_marked_for_deletion;
+  single_db.erase(blob_pair);
+  if (single_db.empty()) {
+    use_tracker_.erase(db_pair);
+    if (db_marked_for_deletion) {
+      delete_in_backend = true;
+      blob_key = DatabaseMetaDataKey::kAllBlobsKey;
+      deleted_dbs_.erase(db_to_delete);
+    }
+  }
+  if (delete_in_backend)
+    backing_store_->ReportBlobUnused(database_id, blob_key);
+  if (use_tracker_.empty()) {
+    backing_store_->factory()->ReportOutstandingBlobs(
+        backing_store_->origin_url(), false);
+  }
+}
+
+bool IndexedDBActiveBlobRegistry::MarkDeletedCheckIfUsed(int64 database_id,
+                                                         int64 blob_key) {
+  DCHECK(backing_store_->task_runner()->RunsTasksOnCurrentThread());
+  DCHECK(KeyPrefix::IsValidDatabaseId(database_id));
+  AllDBsMap::iterator db_pair = use_tracker_.find(database_id);
+  if (db_pair == use_tracker_.end())
+    return false;

[cmumford, 2014/03/24 23:14:35]

Should this be a failed DCHECK, or is it a legitimate situation to be in?

[ericu, 2014/03/25 01:22:14]

It's legit; the tracker only contains entries for blobs that are in use, and
their databases, not for all existing blobs.

+
+  if (blob_key == DatabaseMetaDataKey::kAllBlobsKey) {
+    deleted_dbs_.insert(database_id);
+    return true;
+  }
+
+  SingleDBMap& single_db = db_pair->second;
+  SingleDBMap::iterator iter = single_db.find(blob_key);
+  if (iter == single_db.end())
+    return false;
+
+  iter->second = true;
+  return true;
+}
+
+void IndexedDBActiveBlobRegistry::ReleaseBlobRefThreadSafe(
+    scoped_refptr<base::TaskRunner> task_runner,
+    base::WeakPtr<IndexedDBActiveBlobRegistry> weak_ptr,
+    int64 database_id,
+    int64 blob_key,
+    const base::FilePath& unused) {
+  task_runner->PostTask(FROM_HERE,
+                        base::Bind(&IndexedDBActiveBlobRegistry::ReleaseBlobRef,
+                                   weak_ptr,
+                                   database_id,
+                                   blob_key));
+}
+
+webkit_blob::ShareableFileReference::FinalReleaseCallback
+IndexedDBActiveBlobRegistry::GetFinalReleaseCallback(int64 database_id,
+                                                     int64 blob_key) {
+  return base::Bind(
+      &IndexedDBActiveBlobRegistry::ReleaseBlobRefThreadSafe,
+      scoped_refptr<base::TaskRunner>(backing_store_->task_runner()),
+      weak_factory_.GetWeakPtr(),
+      database_id,
+      blob_key);
+}
+
+base::Closure IndexedDBActiveBlobRegistry::GetAddBlobRefCallback(
+    int64 database_id,
+    int64 blob_key) {
+  return base::Bind(&IndexedDBActiveBlobRegistry::AddBlobRef,
+                    weak_factory_.GetWeakPtr(),
+                    database_id,
+                    blob_key);
+}
+
+void IndexedDBActiveBlobRegistry::ForceShutdown() {

[jsbell, 2014/03/20 18:04:33]

This doesn't actually "drop its reference to the backing store" as the comment
says; since it's a raw ptr, that's not strictly necessary, but should it null it
out and other methods can DCHECK that it's non-null?

[ericu, 2014/03/25 01:22:14]

Comment: fixed; it dated back from an older way of doing things.
NULL/DCHECK: Good idea; done.

+  weak_factory_.InvalidateWeakPtrs();
+  use_tracker_.clear();
+}
+
+}  // namespace content