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+/* -*- 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 GFX_TRANSACTION_ID_ALLOCATOR_H
+#define GFX_TRANSACTION_ID_ALLOCATOR_H
+
+#include "nsISupportsImpl.h"
+#include "mozilla/layers/LayersTypes.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/VsyncDispatcher.h"
+
+namespace mozilla {
+namespace layers {
+
+class TransactionIdAllocator {
+ protected:
+ virtual ~TransactionIdAllocator() = default;
+
+ public:
+ NS_INLINE_DECL_REFCOUNTING(TransactionIdAllocator)
+
+ /**
+ * Allocate a unique id number for the current refresh tick, can
+ * only be called while IsInRefresh().
+ *
+ * If too many id's are allocated without being returned then
+ * the refresh driver will suspend until they catch up. This
+ * "throttling" behaviour can be skipped by passing aThrottle=false.
+ * Otherwise call sites should generally be passing aThrottle=true.
+ */
+ virtual TransactionId GetTransactionId(bool aThrottle) = 0;
+
+ /**
+ * Return the transaction id that for the last non-revoked transaction.
+ * This allows the caller to tell whether a composite was triggered by
+ * a paint that occurred after a call to TransactionId().
+ */
+ virtual TransactionId LastTransactionId() const = 0;
+
+ /**
+ * Notify that all work (including asynchronous composites)
+ * for a given transaction id has been completed.
+ *
+ * If the refresh driver has been suspended because
+ * of having too many outstanding id's, then this may
+ * resume it.
+ */
+ virtual void NotifyTransactionCompleted(TransactionId aTransactionId) = 0;
+
+ /**
+ * Revoke a transaction id that isn't needed to track
+ * completion of asynchronous work. This is similar
+ * to NotifyTransactionCompleted except avoids
+ * return ordering issues.
+ */
+ virtual void RevokeTransactionId(TransactionId aTransactionId) = 0;
+
+ /**
+ * Stop waiting for pending transactions, if any.
+ *
+ * This is used when ClientLayerManager is assigning to another refresh
+ * driver, and the current refresh driver may never receive transaction
+ * completed notifications.
+ */
+ virtual void ClearPendingTransactions() = 0;
+
+ /**
+ * Transaction id is usually initialized as 0, however when ClientLayerManager
+ * switches to another refresh driver, completed transactions of the previous
+ * refresh driver could be delivered and confuse the newly adopted refresh
+ * driver. To prevent this situation, use this function to reset transaction
+ * id to the last transaction id from previous refresh driver, so that all
+ * completed transactions of previous refresh driver will be ignored.
+ */
+ virtual void ResetInitialTransactionId(TransactionId aTransactionId) = 0;
+
+ /**
+ * Get the start time of the current refresh tick.
+ */
+ virtual mozilla::TimeStamp GetTransactionStart() = 0;
+
+ virtual VsyncId GetVsyncId() = 0;
+
+ virtual mozilla::TimeStamp GetVsyncStart() = 0;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif /* GFX_TRANSACTION_ID_ALLOCATOR_H */