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       1             : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
       2             :  * This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #ifndef GFX_TRANSACTION_ID_ALLOCATOR_H
       7             : #define GFX_TRANSACTION_ID_ALLOCATOR_H
       8             : 
       9             : #include "nsISupportsImpl.h"
      10             : #include "mozilla/TimeStamp.h"
      11             : 
      12             : namespace mozilla {
      13             : namespace layers {
      14             : 
      15          28 : class TransactionIdAllocator {
      16             : protected:
      17           0 :   virtual ~TransactionIdAllocator() {}
      18             : 
      19             : public:
      20         246 :   NS_INLINE_DECL_REFCOUNTING(TransactionIdAllocator)
      21             : 
      22             :   /**
      23             :    * Allocate a unique id number for the current refresh tick, can
      24             :    * only be called while IsInRefresh().
      25             :    *
      26             :    * If too many id's are allocated without being returned then
      27             :    * the refresh driver will suspend until they catch up. This
      28             :    * "throttling" behaviour can be skipped by passing aThrottle=false.
      29             :    * Otherwise call sites should generally be passing aThrottle=true.
      30             :    */
      31             :   virtual uint64_t GetTransactionId(bool aThrottle) = 0;
      32             : 
      33             :   /**
      34             :    * Return the transaction id that for the last non-revoked transaction.
      35             :    * This allows the caller to tell whether a composite was triggered by
      36             :    * a paint that occurred after a call to TransactionId().
      37             :    */
      38             :   virtual uint64_t LastTransactionId() const = 0;
      39             : 
      40             :   /**
      41             :    * Notify that all work (including asynchronous composites)
      42             :    * for a given transaction id has been completed.
      43             :    *
      44             :    * If the refresh driver has been suspended because
      45             :    * of having too many outstanding id's, then this may
      46             :    * resume it.
      47             :    */
      48             :   virtual void NotifyTransactionCompleted(uint64_t aTransactionId) = 0;
      49             : 
      50             :   /**
      51             :    * Revoke a transaction id that isn't needed to track
      52             :    * completion of asynchronous work. This is similar
      53             :    * to NotifyTransactionCompleted except avoids
      54             :    * return ordering issues.
      55             :    */
      56             :   virtual void RevokeTransactionId(uint64_t aTransactionId) = 0;
      57             : 
      58             :   /**
      59             :    * Stop waiting for pending transactions, if any.
      60             :    *
      61             :    * This is used when ClientLayerManager is assigning to another refresh
      62             :    * driver, and the current refresh driver may never receive transaction
      63             :    * completed notifications.
      64             :    */
      65             :   virtual void ClearPendingTransactions() = 0;
      66             : 
      67             :   /**
      68             :    * Transaction id is usually initialized as 0, however when ClientLayerManager
      69             :    * switches to another refresh driver, completed transactions of the previous
      70             :    * refresh driver could be delivered and confuse the newly adopted refresh
      71             :    * driver. To prevent this situation, use this function to reset transaction
      72             :    * id to the last transaction id from previous refresh driver, so that all
      73             :    * completed transactions of previous refresh driver will be ignored.
      74             :    */
      75             :   virtual void ResetInitialTransactionId(uint64_t aTransactionId) = 0;
      76             : 
      77             :   /**
      78             :    * Get the start time of the current refresh tick.
      79             :    */
      80             :   virtual mozilla::TimeStamp GetTransactionStart() = 0;
      81             : };
      82             : 
      83             : } // namespace layers
      84             : } // namespace mozilla
      85             : 
      86             : 
      87             : #endif /* GFX_TRANSACTION_ID_ALLOCATOR_H */