root/content/browser/dom_storage/dom_storage_context_impl.cc

DEFINITIONS

1. scavenging_started_
2. GetStorageNamespace
3. GetLocalStorageUsage
4. GetSessionStorageUsage
5. DeleteLocalStorage
6. DeleteSessionStorage
7. Shutdown
8. AddEventObserver
9. RemoveEventObserver
10. NotifyItemSet
11. NotifyItemRemoved
12. NotifyAreaCleared
13. NotifyAliasSessionMerged
14. AllocatePersistentSessionId
15. CreateSessionNamespace
16. DeleteSessionNamespace
17. MaybeShutdownSessionNamespace
18. CloneSessionNamespace
19. CreateAliasSessionNamespace
20. ClearSessionOnlyOrigins
21. SetSaveSessionStorageOnDisk
22. StartScavengingUnusedSessionStorage
23. FindUnusedNamespaces
24. FindUnusedNamespacesInCommitSequence
25. DeleteNextUnusedNamespace
26. DeleteNextUnusedNamespaceInCommitSequence
27. AddTransactionLogProcessId
28. RemoveTransactionLogProcessId
29. MergeSessionStorage

// 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 "base/bind.h"
#include "base/bind_helpers.h"
#include "base/file_util.h"
#include "base/files/file_enumerator.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 "webkit/browser/quota/special_storage_policy.h"

namespace content {

static const int kSessionStoraceScavengingSeconds = 60;

DOMStorageContextImpl::DOMStorageContextImpl(
    const base::FilePath& localstorage_directory,
    const base::FilePath& sessionstorage_directory,
    quota::SpecialStoragePolicy* special_storage_policy,
    DOMStorageTaskRunner* task_runner)
    : localstorage_directory_(localstorage_directory),
      sessionstorage_directory_(sessionstorage_directory),
      task_runner_(task_runner),
      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();
}

DOMStorageContextImpl::~DOMStorageContextImpl() {
  if (session_storage_database_.get()) {
    // SessionStorageDatabase shouldn't be deleted right away: deleting it will
    // potentially involve waiting in leveldb::DBImpl::~DBImpl, and waiting
    // shouldn't happen on this thread.
    SessionStorageDatabase* to_release = session_storage_database_.get();
    to_release->AddRef();
    session_storage_database_ = NULL;
    task_runner_->PostShutdownBlockingTask(
        FROM_HERE,
        DOMStorageTaskRunner::COMMIT_SEQUENCE,
        base::Bind(&SessionStorageDatabase::Release,
                   base::Unretained(to_release)));
  }
}

DOMStorageNamespace* DOMStorageContextImpl::GetStorageNamespace(
    int64 namespace_id) {
  if (is_shutdown_)
    return NULL;
  StorageNamespaceMap::iterator found = namespaces_.find(namespace_id);
  if (found == namespaces_.end()) {
    if (namespace_id == kLocalStorageNamespaceId) {
      if (!localstorage_directory_.empty()) {
        if (!base::CreateDirectory(localstorage_directory_)) {
          LOG(ERROR) << "Failed to create 'Local Storage' directory,"
                        " falling back to in-memory only.";
          localstorage_directory_ = base::FilePath();
        }
      }
      DOMStorageNamespace* local =
          new DOMStorageNamespace(localstorage_directory_, task_runner_.get());
      namespaces_[kLocalStorageNamespaceId] = local;
      return local;
    }
    return NULL;
  }
  return found->second.get();
}

void DOMStorageContextImpl::GetLocalStorageUsage(
    std::vector<LocalStorageUsageInfo>* infos,
    bool include_file_info) {
  if (localstorage_directory_.empty())
    return;
  base::FileEnumerator enumerator(localstorage_directory_, false,
                                  base::FileEnumerator::FILES);
  for (base::FilePath path = enumerator.Next(); !path.empty();
       path = enumerator.Next()) {
    if (path.MatchesExtension(DOMStorageArea::kDatabaseFileExtension)) {
      LocalStorageUsageInfo info;
      info.origin = DOMStorageArea::OriginFromDatabaseFileName(path);
      if (include_file_info) {
        base::FileEnumerator::FileInfo find_info = enumerator.GetInfo();
        info.data_size = find_info.GetSize();
        info.last_modified = find_info.GetLastModifiedTime();
      }
      infos->push_back(info);
    }
  }
}

void DOMStorageContextImpl::GetSessionStorageUsage(
    std::vector<SessionStorageUsageInfo>* infos) {
  if (!session_storage_database_.get())
    return;
  std::map<std::string, std::vector<GURL> > namespaces_and_origins;
  session_storage_database_->ReadNamespacesAndOrigins(
      &namespaces_and_origins);
  for (std::map<std::string, std::vector<GURL> >::const_iterator it =
           namespaces_and_origins.begin();
       it != namespaces_and_origins.end(); ++it) {
    for (std::vector<GURL>::const_iterator origin_it = it->second.begin();
         origin_it != it->second.end(); ++origin_it) {
      SessionStorageUsageInfo info;
      info.persistent_namespace_id = it->first;
      info.origin = *origin_it;
      infos->push_back(info);
    }
  }
}

void DOMStorageContextImpl::DeleteLocalStorage(const GURL& origin) {
  DCHECK(!is_shutdown_);
  DOMStorageNamespace* local = GetStorageNamespace(kLocalStorageNamespaceId);
  local->DeleteLocalStorageOrigin(origin);
  // Synthesize a 'cleared' event if the area is open so CachedAreas in
  // renderers get emptied out too.
  DOMStorageArea* area = local->GetOpenStorageArea(origin);
  if (area)
    NotifyAreaCleared(area, origin);
}

void DOMStorageContextImpl::DeleteSessionStorage(
    const SessionStorageUsageInfo& usage_info) {
  DCHECK(!is_shutdown_);
  DOMStorageNamespace* dom_storage_namespace = NULL;
  std::map<std::string, int64>::const_iterator it =
      persistent_namespace_id_to_namespace_id_.find(
          usage_info.persistent_namespace_id);
  if (it != persistent_namespace_id_to_namespace_id_.end()) {
    dom_storage_namespace = GetStorageNamespace(it->second);
  } else {
    int64 namespace_id = AllocateSessionId();
    CreateSessionNamespace(namespace_id, usage_info.persistent_namespace_id);
    dom_storage_namespace = GetStorageNamespace(namespace_id);
  }
  dom_storage_namespace->DeleteSessionStorageOrigin(usage_info.origin);
  // Synthesize a 'cleared' event if the area is open so CachedAreas in
  // renderers get emptied out too.
  DOMStorageArea* area =
      dom_storage_namespace->GetOpenStorageArea(usage_info.origin);
  if (area)
    NotifyAreaCleared(area, usage_info.origin);
}

void DOMStorageContextImpl::Shutdown() {
  is_shutdown_ = true;
  StorageNamespaceMap::const_iterator it = namespaces_.begin();
  for (; it != namespaces_.end(); ++it)
    it->second->Shutdown();

  if (localstorage_directory_.empty() && !session_storage_database_.get())
    return;

  // Respect the content policy settings about what to
  // keep and what to discard.
  if (force_keep_session_state_)
    return;  // Keep everything.

  bool has_session_only_origins =
      special_storage_policy_.get() &&
      special_storage_policy_->HasSessionOnlyOrigins();

  if (has_session_only_origins) {
    // We may have to delete something. We continue on the
    // commit sequence after area shutdown tasks have cycled
    // thru that sequence (and closed their database files).
    bool success = task_runner_->PostShutdownBlockingTask(
        FROM_HERE,
        DOMStorageTaskRunner::COMMIT_SEQUENCE,
        base::Bind(&DOMStorageContextImpl::ClearSessionOnlyOrigins, this));
    DCHECK(success);
  }
}

void DOMStorageContextImpl::AddEventObserver(EventObserver* observer) {
  event_observers_.AddObserver(observer);
}

void DOMStorageContextImpl::RemoveEventObserver(EventObserver* observer) {
  event_observers_.RemoveObserver(observer);
}

void DOMStorageContextImpl::NotifyItemSet(
    const DOMStorageArea* area,
    const base::string16& key,
    const base::string16& new_value,
    const base::NullableString16& old_value,
    const GURL& page_url) {
  FOR_EACH_OBSERVER(
      EventObserver, event_observers_,
      OnDOMStorageItemSet(area, key, new_value, old_value, page_url));
}

void DOMStorageContextImpl::NotifyItemRemoved(
    const DOMStorageArea* area,
    const base::string16& key,
    const base::string16& old_value,
    const GURL& page_url) {
  FOR_EACH_OBSERVER(
      EventObserver, event_observers_,
      OnDOMStorageItemRemoved(area, key, old_value, page_url));
}

void DOMStorageContextImpl::NotifyAreaCleared(
    const DOMStorageArea* area,
    const GURL& page_url) {
  FOR_EACH_OBSERVER(
      EventObserver, event_observers_,
      OnDOMStorageAreaCleared(area, page_url));
}

void DOMStorageContextImpl::NotifyAliasSessionMerged(
    int64 namespace_id,
    DOMStorageNamespace* old_alias_master_namespace) {
  FOR_EACH_OBSERVER(
      EventObserver, event_observers_,
      OnDOMSessionStorageReset(namespace_id));
  if (old_alias_master_namespace)
    MaybeShutdownSessionNamespace(old_alias_master_namespace);
}

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_)
    return;
  DCHECK(namespace_id != kLocalStorageNamespaceId);
  DCHECK(namespaces_.find(namespace_id) == namespaces_.end());
  namespaces_[namespace_id] = new DOMStorageNamespace(
      namespace_id, persistent_namespace_id, session_storage_database_.get(),
      task_runner_.get());
  persistent_namespace_id_to_namespace_id_[persistent_namespace_id] =
      namespace_id;
}

void DOMStorageContextImpl::DeleteSessionNamespace(
    int64 namespace_id, bool should_persist_data) {
  DCHECK_NE(kLocalStorageNamespaceId, namespace_id);
  StorageNamespaceMap::const_iterator it = namespaces_.find(namespace_id);
  if (it == namespaces_.end() ||
      it->second->ready_for_deletion_pending_aliases()) {
    return;
  }
  it->second->set_ready_for_deletion_pending_aliases(true);
  DOMStorageNamespace* alias_master = it->second->alias_master_namespace();
  if (alias_master) {
    DCHECK(it->second->num_aliases() == 0);
    DCHECK(alias_master->alias_master_namespace() == NULL);
    if (should_persist_data)
      alias_master->set_must_persist_at_shutdown(true);
    if (it->second->DecrementMasterAliasCount())
      MaybeShutdownSessionNamespace(alias_master);
    namespaces_.erase(namespace_id);
  } else {
    if (should_persist_data)
      it->second->set_must_persist_at_shutdown(true);
    MaybeShutdownSessionNamespace(it->second);
  }
}

void DOMStorageContextImpl::MaybeShutdownSessionNamespace(
    DOMStorageNamespace* ns) {
  if (ns->num_aliases() > 0 || !ns->ready_for_deletion_pending_aliases())
    return;
  DCHECK_EQ(ns->num_aliases(), 0);
  DCHECK(ns->alias_master_namespace() == NULL);
  std::string persistent_namespace_id =  ns->persistent_namespace_id();
  if (session_storage_database_.get()) {
    if (!ns->must_persist_at_shutdown()) {
      task_runner_->PostShutdownBlockingTask(
          FROM_HERE,
          DOMStorageTaskRunner::COMMIT_SEQUENCE,
          base::Bind(
              base::IgnoreResult(&SessionStorageDatabase::DeleteNamespace),
              session_storage_database_,
              persistent_namespace_id));
    } else {
      // Ensure that the data gets committed before we shut down.
      ns->Shutdown();
      if (!scavenging_started_) {
        // Protect the persistent namespace ID from scavenging.
        protected_persistent_session_ids_.insert(persistent_namespace_id);
      }
    }
  }
  persistent_namespace_id_to_namespace_id_.erase(persistent_namespace_id);
  namespaces_.erase(ns->namespace_id());
}

void DOMStorageContextImpl::CloneSessionNamespace(
    int64 existing_id, int64 new_id,
    const std::string& new_persistent_id) {
  if (is_shutdown_)
    return;
  DCHECK_NE(kLocalStorageNamespaceId, existing_id);
  DCHECK_NE(kLocalStorageNamespaceId, new_id);
  StorageNamespaceMap::iterator found = namespaces_.find(existing_id);
  if (found != namespaces_.end())
    namespaces_[new_id] = found->second->Clone(new_id, new_persistent_id);
  else
    CreateSessionNamespace(new_id, new_persistent_id);
}

void DOMStorageContextImpl::CreateAliasSessionNamespace(
    int64 existing_id, int64 new_id,
    const std::string& persistent_id) {
  if (is_shutdown_)
    return;
  DCHECK_NE(kLocalStorageNamespaceId, existing_id);
  DCHECK_NE(kLocalStorageNamespaceId, new_id);
  StorageNamespaceMap::iterator found = namespaces_.find(existing_id);
  if (found != namespaces_.end()) {
    namespaces_[new_id] = found->second->CreateAlias(new_id);
  } else {
    CreateSessionNamespace(new_id, persistent_id);
  }
}

void DOMStorageContextImpl::ClearSessionOnlyOrigins() {
  if (!localstorage_directory_.empty()) {
    std::vector<LocalStorageUsageInfo> infos;
    const bool kDontIncludeFileInfo = false;
    GetLocalStorageUsage(&infos, kDontIncludeFileInfo);
    for (size_t i = 0; i < infos.size(); ++i) {
      const GURL& origin = infos[i].origin;
      if (special_storage_policy_->IsStorageProtected(origin))
        continue;
      if (!special_storage_policy_->IsStorageSessionOnly(origin))
        continue;

      base::FilePath database_file_path = localstorage_directory_.Append(
          DOMStorageArea::DatabaseFileNameFromOrigin(origin));
      sql::Connection::Delete(database_file_path);
    }
  }
  if (session_storage_database_.get()) {
    std::vector<SessionStorageUsageInfo> infos;
    GetSessionStorageUsage(&infos);
    for (size_t i = 0; i < infos.size(); ++i) {
      const GURL& origin = infos[i].origin;
      if (special_storage_policy_->IsStorageProtected(origin))
        continue;
      if (!special_storage_policy_->IsStorageSessionOnly(origin))
        continue;
      session_storage_database_->DeleteArea(infos[i].persistent_namespace_id,
                                            origin);
    }
  }
}

void DOMStorageContextImpl::SetSaveSessionStorageOnDisk() {
  DCHECK(namespaces_.empty());
  if (!sessionstorage_directory_.empty()) {
    session_storage_database_ = new SessionStorageDatabase(
        sessionstorage_directory_);
  }
}

void DOMStorageContextImpl::StartScavengingUnusedSessionStorage() {
  if (session_storage_database_.get()) {
    task_runner_->PostDelayedTask(
        FROM_HERE, base::Bind(&DOMStorageContextImpl::FindUnusedNamespaces,
                              this),
        base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
  }
}

void DOMStorageContextImpl::FindUnusedNamespaces() {
  DCHECK(session_storage_database_.get());
  if (scavenging_started_)
    return;
  scavenging_started_ = true;
  std::set<std::string> namespace_ids_in_use;
  for (StorageNamespaceMap::const_iterator it = namespaces_.begin();
       it != namespaces_.end(); ++it)
    namespace_ids_in_use.insert(it->second->persistent_namespace_id());
  std::set<std::string> protected_persistent_session_ids;
  protected_persistent_session_ids.swap(protected_persistent_session_ids_);
  task_runner_->PostShutdownBlockingTask(
      FROM_HERE, DOMStorageTaskRunner::COMMIT_SEQUENCE,
      base::Bind(
          &DOMStorageContextImpl::FindUnusedNamespacesInCommitSequence,
          this, namespace_ids_in_use, protected_persistent_session_ids));
}

void DOMStorageContextImpl::FindUnusedNamespacesInCommitSequence(
    const std::set<std::string>& namespace_ids_in_use,
    const std::set<std::string>& protected_persistent_session_ids) {
  DCHECK(session_storage_database_.get());
  // Delete all namespaces which don't have an associated DOMStorageNamespace
  // alive.
  std::map<std::string, std::vector<GURL> > namespaces_and_origins;
  session_storage_database_->ReadNamespacesAndOrigins(&namespaces_and_origins);
  for (std::map<std::string, std::vector<GURL> >::const_iterator it =
           namespaces_and_origins.begin();
       it != namespaces_and_origins.end(); ++it) {
    if (namespace_ids_in_use.find(it->first) == namespace_ids_in_use.end() &&
        protected_persistent_session_ids.find(it->first) ==
        protected_persistent_session_ids.end()) {
      deletable_persistent_namespace_ids_.push_back(it->first);
    }
  }
  if (!deletable_persistent_namespace_ids_.empty()) {
    task_runner_->PostDelayedTask(
        FROM_HERE, base::Bind(
            &DOMStorageContextImpl::DeleteNextUnusedNamespace,
            this),
        base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
  }
}

void DOMStorageContextImpl::DeleteNextUnusedNamespace() {
  if (is_shutdown_)
    return;
  task_runner_->PostShutdownBlockingTask(
        FROM_HERE, DOMStorageTaskRunner::COMMIT_SEQUENCE,
        base::Bind(
            &DOMStorageContextImpl::DeleteNextUnusedNamespaceInCommitSequence,
            this));
}

void DOMStorageContextImpl::DeleteNextUnusedNamespaceInCommitSequence() {
  if (deletable_persistent_namespace_ids_.empty())
    return;
  const std::string& persistent_id = deletable_persistent_namespace_ids_.back();
  session_storage_database_->DeleteNamespace(persistent_id);
  deletable_persistent_namespace_ids_.pop_back();
  if (!deletable_persistent_namespace_ids_.empty()) {
    task_runner_->PostDelayedTask(
        FROM_HERE, base::Bind(
            &DOMStorageContextImpl::DeleteNextUnusedNamespace,
            this),
        base::TimeDelta::FromSeconds(kSessionStoraceScavengingSeconds));
  }
}

void DOMStorageContextImpl::AddTransactionLogProcessId(int64 namespace_id,
                                                       int process_id) {
  DCHECK_NE(kLocalStorageNamespaceId, namespace_id);
  StorageNamespaceMap::const_iterator it = namespaces_.find(namespace_id);
  if (it == namespaces_.end())
    return;
  it->second->AddTransactionLogProcessId(process_id);
}

void DOMStorageContextImpl::RemoveTransactionLogProcessId(int64 namespace_id,
                                                       int process_id) {
  DCHECK_NE(kLocalStorageNamespaceId, namespace_id);
  StorageNamespaceMap::const_iterator it = namespaces_.find(namespace_id);
  if (it == namespaces_.end())
    return;
  it->second->RemoveTransactionLogProcessId(process_id);
}

SessionStorageNamespace::MergeResult
DOMStorageContextImpl::MergeSessionStorage(
    int64 namespace1_id, bool actually_merge, int process_id,
    int64 namespace2_id) {
  DCHECK_NE(kLocalStorageNamespaceId, namespace1_id);
  DCHECK_NE(kLocalStorageNamespaceId, namespace2_id);
  StorageNamespaceMap::const_iterator it = namespaces_.find(namespace1_id);
  if (it == namespaces_.end())
    return SessionStorageNamespace::MERGE_RESULT_NAMESPACE_NOT_FOUND;
  DOMStorageNamespace* ns1 = it->second;
  it = namespaces_.find(namespace2_id);
  if (it == namespaces_.end())
    return SessionStorageNamespace::MERGE_RESULT_NAMESPACE_NOT_FOUND;
  DOMStorageNamespace* ns2 = it->second;
  return ns1->Merge(actually_merge, process_id, ns2, this);
}

}  // namespace content