dom/cache/Action.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_dom_cache_Action_h
   8 #define mozilla_dom_cache_Action_h
   9
  10 #include "mozilla/Atomics.h"
  11 #include "mozilla/dom/cache/Types.h"
  12 #include "mozilla/dom/SafeRefPtr.h"
  13 #include "nsISupportsImpl.h"
  14
  15 class mozIStorageConnection;
  16
  17 namespace mozilla::dom::cache {
  18
  19 class Action : public SafeRefCounted<Action> {
  20  public:
  21   class Resolver {
  22    public:
  23     Resolver& operator=(const Resolver& aRHS) = delete;
  24
  25     // Note: Action must drop Resolver ref after calling Resolve()!
  26     // Note: Must be called on the same thread used to execute
  27     //       Action::RunOnTarget().
  28     virtual void Resolve(nsresult aRv) = 0;
  29
  30     inline SafeRefPtr<Action::Resolver> SafeRefPtrFromThis() {
  31       return SafeRefPtr<Action::Resolver>{this, AcquireStrongRefFromRawPtr{}};
  32     }
  33
  34     NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
  35   };
  36
  37   // Class containing data that can be opportunistically shared between
  38   // multiple Actions running on the same thread/Context.  In theory
  39   // this could be abstracted to a generic key/value map, but for now
  40   // just explicitly provide accessors for the data we need.
  41   class Data {
  42    public:
  43     virtual mozIStorageConnection* GetConnection() const = 0;
  44
  45     virtual void SetConnection(mozIStorageConnection* aConn) = 0;
  46   };
  47
  48   // virtual because deleted through base class pointer
  49   virtual ~Action();
  50
  51   // Execute operations on the target thread.  Once complete call
  52   // Resolver::Resolve().  This can be done sync or async.
  53   // Note: Action should hold Resolver ref until its ready to call Resolve().
  54   // Note: The "target" thread is determined when the Action is scheduled on
  55   //       Context.  The Action should not assume any particular thread is used.
  56   virtual void RunOnTarget(
  57       SafeRefPtr<Resolver> aResolver,
  58       const Maybe<CacheDirectoryMetadata>& aDirectoryMetadata,
  59       Data* aOptionalData) = 0;
  60
  61   // Called on initiating thread when the Action is canceled.  The Action is
  62   // responsible for calling Resolver::Resolve() as normal; either with a
  63   // normal error code or NS_ERROR_ABORT.  If CancelOnInitiatingThread() is
  64   // called after Resolve() has already occurred, then the cancel can be
  65   // ignored.
  66   //
  67   // Cancellation is a best effort to stop processing as soon as possible, but
  68   // does not guarantee the Action will not run.
  69   //
  70   // CancelOnInitiatingThread() may be called more than once.  Subsequent
  71   // calls should have no effect.
  72   //
  73   // Default implementation sets an internal cancellation flag that can be
  74   // queried with IsCanceled().
  75   virtual void CancelOnInitiatingThread();
  76
  77   // Executed on the initiating thread and is passed the nsresult given to
  78   // Resolver::Resolve().
  79   virtual void CompleteOnInitiatingThread(nsresult aRv) {}
  80
  81   // Executed on the initiating thread.  If this Action will operate on the
  82   // given cache ID then override this to return true.
  83   virtual bool MatchesCacheId(CacheId aCacheId) const { return false; }
  84
  85   NS_DECL_OWNINGTHREAD
  86   MOZ_DECLARE_REFCOUNTED_TYPENAME(cache::Action)
  87
  88  protected:
  89   Action();
  90
  91   // Check if this Action has been canceled.  May be called from any thread,
  92   // but typically used from the target thread.
  93   bool IsCanceled() const;
  94
  95  private:
  96   // Accessible from any thread.
  97   Atomic<bool> mCanceled;
  98 };
  99
 100 }  // namespace mozilla::dom::cache
 101
 102 #endif  // mozilla_dom_cache_Action_h