offset namespace ids

content/browser/dom_storage/dom_storage_context_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 "content/browser/dom_storage/dom_storage_context_impl.h"
 
+#include <stdlib.h>
+
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/guid.h"
 #include "base/location.h"
 #include "base/time/time.h"
 #include "content/browser/dom_storage/dom_storage_area.h"
 #include "content/browser/dom_storage/dom_storage_database.h"
 #include "content/browser/dom_storage/dom_storage_namespace.h"
 #include "content/browser/dom_storage/dom_storage_task_runner.h"
 #include "content/browser/dom_storage/session_storage_database.h"
 #include "content/common/dom_storage/dom_storage_types.h"
 #include "content/public/browser/dom_storage_context.h"
 #include "content/public/browser/local_storage_usage_info.h"
 #include "content/public/browser/session_storage_usage_info.h"
 #include "storage/browser/quota/special_storage_policy.h"
 
 namespace content {
 
 static const int kSessionStoraceScavengingSeconds = 60;
+static int g_session_id_offset_sequence;

[jsbell, 2015/01/30 18:10:16]

explicitly initialize to 0?

(just for readability; it's done implicitly)

Also, can you comment here why this is used? (i.e. same as the CL description)

 
 DOMStorageContextImpl::DOMStorageContextImpl(
     const base::FilePath& localstorage_directory,
     const base::FilePath& sessionstorage_directory,
     storage::SpecialStoragePolicy* special_storage_policy,
     DOMStorageTaskRunner* task_runner)
     : localstorage_directory_(localstorage_directory),
       sessionstorage_directory_(sessionstorage_directory),
       task_runner_(task_runner),
+      session_id_offset_(abs((g_session_id_offset_sequence++ % 10)) * 1000),
       is_shutdown_(false),
       force_keep_session_state_(false),
       special_storage_policy_(special_storage_policy),
       scavenging_started_(false) {
   // AtomicSequenceNum starts at 0 but we want to start session
   // namespace ids at one since zero is reserved for the
   // kLocalStorageNamespaceId.
   session_id_sequence_.GetNext();
 }
 
@@ skipping 173 matching lines @@
 }
 
 void DOMStorageContextImpl::NotifyAreaCleared(
     const DOMStorageArea* area,
     const GURL& page_url) {
   FOR_EACH_OBSERVER(
       EventObserver, event_observers_,
       OnDOMStorageAreaCleared(area, page_url));
 }
 
+int64 DOMStorageContextImpl::AllocateSessionId() {
+  return session_id_sequence_.GetNext() + session_id_offset_;
+}
+
 std::string DOMStorageContextImpl::AllocatePersistentSessionId() {
   std::string guid = base::GenerateGUID();
   std::replace(guid.begin(), guid.end(), '-', '_');
   return guid;
 }
 
 void DOMStorageContextImpl::CreateSessionNamespace(
     int64 namespace_id,
     const std::string& persistent_namespace_id) {
   if (is_shutdown_)
@@ skipping 162 matching lines @@
   if (!deletable_persistent_namespace_ids_.empty()) {
     task_runner_->PostDelayedTask(
         FROM_HERE, base::Bind(
             &DOMStorageContextImpl::DeleteNextUnusedNamespace,
             this),
         base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
   }
 }
 
 }  // namespace content