1 files changed, 78 insertions, 0 deletions
diff --git a/dom/file/ipc/RemoteLazyInputStreamStorage.h b/dom/file/ipc/RemoteLazyInputStreamStorage.h
new file mode 100644
index 0000000000..296a8d9313
--- /dev/null
+++ b/dom/file/ipc/RemoteLazyInputStreamStorage.h
@@ -0,0 +1,78 @@
+/* -*- 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_RemoteLazyInputStreamStorage_h
+#define mozilla_RemoteLazyInputStreamStorage_h
+
+#include "mozilla/RefPtr.h"
+#include "nsClassHashtable.h"
+#include "nsIObserver.h"
+
+class nsIInputStream;
+struct nsID;
+
+namespace mozilla {
+
+class NS_NO_VTABLE RemoteLazyInputStreamParentCallback {
+ public:
+  virtual void ActorDestroyed(const nsID& aID) = 0;
+
+  NS_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING
+
+ protected:
+  virtual ~RemoteLazyInputStreamParentCallback() = default;
+};
+
+class RemoteLazyInputStreamStorage final : public nsIObserver {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  // This initializes the singleton and it must be called on the main-thread.
+  static void Initialize();
+
+  static Result<RefPtr<RemoteLazyInputStreamStorage>, nsresult> Get();
+
+  nsISerialEventTarget* TaskQueue() { return mTaskQueue; }
+
+  void AddStream(nsIInputStream* aInputStream, const nsID& aID);
+
+  // Removes and returns the stream corresponding to the nsID. May return a
+  // nullptr if there's no stream stored for the nsID.
+  nsCOMPtr<nsIInputStream> ForgetStream(const nsID& aID);
+
+  bool HasStream(const nsID& aID);
+
+  void GetStream(const nsID& aID, uint64_t aStart, uint64_t aLength,
+                 nsIInputStream** aInputStream);
+
+  void StoreCallback(const nsID& aID,
+                     RemoteLazyInputStreamParentCallback* aCallback);
+
+  already_AddRefed<RemoteLazyInputStreamParentCallback> TakeCallback(
+      const nsID& aID);
+
+  void ActorCreated(const nsID& aID);
+  void ActorDestroyed(const nsID& aID);
+
+ private:
+  RemoteLazyInputStreamStorage() = default;
+  ~RemoteLazyInputStreamStorage() = default;
+
+  nsCOMPtr<nsISerialEventTarget> mTaskQueue;
+
+  struct StreamData {
+    nsCOMPtr<nsIInputStream> mInputStream;
+    RefPtr<RemoteLazyInputStreamParentCallback> mCallback;
+    size_t mActorCount = 0;
+  };
+
+  nsClassHashtable<nsIDHashKey, StreamData> mStorage;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_RemoteLazyInputStreamStorage_h