cached_realm_base.hpp
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////////////////////////////////////////////////////////////////////////////
//
// Copyright 2015 Realm Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
////////////////////////////////////////////////////////////////////////////
#ifndef REALM_CACHED_REALM_BASE_HPP
#define REALM_CACHED_REALM_BASE_HPP
#include <memory>
#include <thread>
namespace realm {
class Realm;
namespace _impl {
// CachedRealmBase stores a weak reference to a Realm instance, along with all of
// the information about a Realm that needs to be accessed from other threads.
// This is needed to avoid forming strong references to the Realm instances on
// other threads, which can produce deadlocks when the last strong reference to
// a Realm instance is released from within a function holding the cache lock.
class CachedRealmBase {
public:
CachedRealmBase(const std::shared_ptr<Realm>& realm, bool cache);
// Get a strong reference to the cached realm
std::shared_ptr<Realm> realm() const { return m_realm.lock(); }
// Does this CachedRealmBase store a Realm instance that should be used on the current thread?
bool is_cached_for_current_thread() const { return m_cache && m_thread_id == std::this_thread::get_id(); }
// Has the Realm instance been destroyed?
bool expired() const { return m_realm.expired(); }
// Is this a CachedRealmBase for the given Realm instance?
bool is_for_realm(Realm* realm) const { return realm == m_realm_key; }
private:
std::weak_ptr<Realm> m_realm;
std::thread::id m_thread_id = std::this_thread::get_id();
void* m_realm_key;
bool m_cache = false;
};
inline CachedRealmBase::CachedRealmBase(const std::shared_ptr<Realm>& realm, bool cache)
: m_realm(realm)
, m_realm_key(realm.get())
, m_cache(cache)
{
}
} // namespace _impl
} // namespace realm
#endif // REALM_CACHED_REALM_BASE_HPP