/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_dom_cache_Manager_h
#define mozilla_dom_cache_Manager_h

#include "mozilla/dom/cache/Types.h"
#include "nsCOMPtr.h"
#include "nsISupportsImpl.h"
#include "nsRefPtr.h"
#include "nsString.h"
#include "nsTArray.h"

class nsIInputStream;
class nsIThread;

namespace mozilla {
namespace dom {
namespace cache {

class CacheOpArgs;
class CacheOpResult;
class CacheRequestResponse;
class Context;
class ManagerId;
struct SavedRequest;
struct SavedResponse;
class StreamList;

// The Manager is class is responsible for performing all of the underlying
// work for a Cache or CacheStorage operation.  The DOM objects and IPC actors
// are basically just plumbing to get the request to the right Manager object
// running in the parent process.
//
// There should be exactly one Manager object for each origin or app using the
// Cache API.  This uniqueness is defined by the ManagerId equality operator.
// The uniqueness is enforced by the Manager GetOrCreate() factory method.
//
// The life cycle of Manager objects is somewhat complex.  While code may
// hold a strong reference to the Manager, it will invalidate itself once it
// believes it has become completely idle.  This is currently determined when
// all of the following conditions occur:
//
//  1) There are no more Manager::Listener objects registered with the Manager
//     by performing a Cache or Storage operation.
//  2) There are no more CacheId references noted via Manager::AddRefCacheId().
//  3) There are no more BodyId references noted via Manager::AddRefBodyId().
//
// In order to keep your Manager alive you should perform an operation to set
// a Listener, call AddRefCacheId(), or call AddRefBodyId().
//
// Even once a Manager becomes invalid, however, it may still continue to
// exist.  This is allowed so that any in-progress Actions can gracefully
// complete.
//
// As an invariant, all Manager objects must cease all IO before shutdown.  This
// is enforced by the Manager::Factory.  If content still holds references to
// Cache DOM objects during shutdown, then all operations will begin rejecting.
class Manager final
{
public:
  // Callback interface implemented by clients of Manager, such as CacheParent
  // and CacheStorageParent.  In general, if you call a Manager method you
  // should expect to receive exactly one On*() callback.  For example, if
  // you call Manager::CacheMatch(), then you should expect to receive
  // OnCacheMatch() back in response.
  //
  // Listener objects are set on a per-operation basis.  So you pass the
  // Listener to a call like Manager::CacheMatch().  Once set in this way,
  // the Manager will continue to reference the Listener until RemoveListener()
  // is called.  This is done to allow the same listener to be used for
  // multiple operations simultaneously without having to maintain an exact
  // count of operations-in-flight.
  //
  // Note, the Manager only holds weak references to Listener objects.
  // Listeners must call Manager::RemoveListener() before they are destroyed
  // to clear these weak references.
  //
  // All public methods should be invoked on the same thread used to create
  // the Manager.
  class Listener
  {
  public:
    // convenience routines
    void
    OnOpComplete(ErrorResult&& aRv, const CacheOpResult& aResult);

    void
    OnOpComplete(ErrorResult&& aRv, const CacheOpResult& aResult,
                 CacheId aOpenedCacheId);

    void
    OnOpComplete(ErrorResult&& aRv, const CacheOpResult& aResult,
                 const SavedResponse& aSavedResponse,
                 StreamList* aStreamList);

    void
    OnOpComplete(ErrorResult&& aRv, const CacheOpResult& aResult,
                 const nsTArray<SavedResponse>& aSavedResponseList,
                 StreamList* aStreamList);

    void
    OnOpComplete(ErrorResult&& aRv, const CacheOpResult& aResult,
                 const nsTArray<SavedRequest>& aSavedRequestList,
                 StreamList* aStreamList);

    // interface to be implemented
    virtual void
    OnOpComplete(ErrorResult&& aRv, const CacheOpResult& aResult,
                 CacheId aOpenedCacheId,
                 const nsTArray<SavedResponse>& aSavedResponseList,
                 const nsTArray<SavedRequest>& aSavedRequestList,
                 StreamList* aStreamList) { }

  protected:
    ~Listener() { }
  };

  enum State
  {
    Open,
    Closing
  };

  static nsresult GetOrCreate(ManagerId* aManagerId, Manager** aManagerOut);
  static already_AddRefed<Manager> Get(ManagerId* aManagerId);

  // Synchronously shutdown from main thread.  This spins the event loop.
  static void ShutdownAllOnMainThread();

  // Must be called by Listener objects before they are destroyed.
  void RemoveListener(Listener* aListener);

  // Must be called by Context objects before they are destroyed.
  void RemoveContext(Context* aContext);

  // Marks the Manager "invalid".  Once the Context completes no new operations
  // will be permitted with this Manager.  New actors will get a new Manager.
  void NoteClosing();

  State GetState() const;

  // If an actor represents a long term reference to a cache or body stream,
  // then they must call AddRefCacheId() or AddRefBodyId().  This will
  // cause the Manager to keep the backing data store alive for the given
  // object.  The actor must then call ReleaseCacheId() or ReleaseBodyId()
  // exactly once for every AddRef*() call it made.  Any delayed deletion
  // will then be performed.
  void AddRefCacheId(CacheId aCacheId);
  void ReleaseCacheId(CacheId aCacheId);
  void AddRefBodyId(const nsID& aBodyId);
  void ReleaseBodyId(const nsID& aBodyId);

  already_AddRefed<ManagerId> GetManagerId() const;

  // Methods to allow a StreamList to register themselves with the Manager.
  // StreamList objects must call RemoveStreamList() before they are destroyed.
  void AddStreamList(StreamList* aStreamList);
  void RemoveStreamList(StreamList* aStreamList);

  void ExecuteCacheOp(Listener* aListener, CacheId aCacheId,
                      const CacheOpArgs& aOpArgs);
  void ExecutePutAll(Listener* aListener, CacheId aCacheId,
                     const nsTArray<CacheRequestResponse>& aPutList,
                     const nsTArray<nsCOMPtr<nsIInputStream>>& aRequestStreamList,
                     const nsTArray<nsCOMPtr<nsIInputStream>>& aResponseStreamList);

  void ExecuteStorageOp(Listener* aListener, Namespace aNamespace,
                        const CacheOpArgs& aOpArgs);

private:
  class Factory;
  class BaseAction;
  class DeleteOrphanedCacheAction;

  class CacheMatchAction;
  class CacheMatchAllAction;
  class CachePutAllAction;
  class CacheDeleteAction;
  class CacheKeysAction;

  class StorageMatchAction;
  class StorageHasAction;
  class StorageOpenAction;
  class StorageDeleteAction;
  class StorageKeysAction;

  typedef uint64_t ListenerId;

  Manager(ManagerId* aManagerId, nsIThread* aIOThread);
  ~Manager();
  void Init(Manager* aOldManager);
  void Shutdown();
  already_AddRefed<Context> CurrentContext();

  ListenerId SaveListener(Listener* aListener);
  Listener* GetListener(ListenerId aListenerId) const;

  bool SetCacheIdOrphanedIfRefed(CacheId aCacheId);
  bool SetBodyIdOrphanedIfRefed(const nsID& aBodyId);
  void NoteOrphanedBodyIdList(const nsTArray<nsID>& aDeletedBodyIdList);

  void MaybeAllowContextToClose();

  nsRefPtr<ManagerId> mManagerId;
  nsCOMPtr<nsIThread> mIOThread;

  // Weak reference cleared by RemoveContext() in Context destructor.
  Context* MOZ_NON_OWNING_REF mContext;

  // Weak references cleared by RemoveListener() in Listener destructors.
  struct ListenerEntry
  {
    ListenerEntry()
      : mId(UINT64_MAX)
      , mListener(nullptr)
    {
    }

    ListenerEntry(ListenerId aId, Listener* aListener)
      : mId(aId)
      , mListener(aListener)
    {
    }

    ListenerId mId;
    Listener* mListener;
  };

  class ListenerEntryIdComparator
  {
  public:
    bool Equals(const ListenerEntry& aA, const ListenerId& aB) const
    {
      return aA.mId == aB;
    }
  };

  class ListenerEntryListenerComparator
  {
  public:
    bool Equals(const ListenerEntry& aA, const Listener* aB) const
    {
      return aA.mListener == aB;
    }
  };

  typedef nsTArray<ListenerEntry> ListenerList;
  ListenerList mListeners;
  static ListenerId sNextListenerId;

  // Weak references cleared by RemoveStreamList() in StreamList destructors.
  nsTArray<StreamList*> mStreamLists;

  bool mShuttingDown;
  State mState;

  struct CacheIdRefCounter
  {
    CacheId mCacheId;
    MozRefCountType mCount;
    bool mOrphaned;
  };
  nsTArray<CacheIdRefCounter> mCacheIdRefs;

  struct BodyIdRefCounter
  {
    nsID mBodyId;
    MozRefCountType mCount;
    bool mOrphaned;
  };
  nsTArray<BodyIdRefCounter> mBodyIdRefs;

public:
  NS_INLINE_DECL_REFCOUNTING(cache::Manager)
};

} // namespace cache
} // namespace dom
} // namespace mozilla

#endif // mozilla_dom_cache_Manager_h
