gfx/layers/TransactionIdAllocator.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 GFX_TRANSACTION_ID_ALLOCATOR_H
   8 #define GFX_TRANSACTION_ID_ALLOCATOR_H
   9
  10 #include "nsISupportsImpl.h"
  11 #include "mozilla/layers/LayersTypes.h"
  12 #include "mozilla/TimeStamp.h"
  13 #include "mozilla/VsyncDispatcher.h"
  14
  15 namespace mozilla {
  16 namespace layers {
  17
  18 class TransactionIdAllocator {
  19  protected:
  20   virtual ~TransactionIdAllocator() = default;
  21
  22  public:
  23   NS_INLINE_DECL_REFCOUNTING(TransactionIdAllocator)
  24
  25   /**
  26    * Allocate a unique id number for the current refresh tick, can
  27    * only be called while IsInRefresh().
  28    *
  29    * If too many id's are allocated without being returned then
  30    * the refresh driver will suspend until they catch up. This
  31    * "throttling" behaviour can be skipped by passing aThrottle=false.
  32    * Otherwise call sites should generally be passing aThrottle=true.
  33    */
  34   virtual TransactionId GetTransactionId(bool aThrottle) = 0;
  35
  36   /**
  37    * Return the transaction id that for the last non-revoked transaction.
  38    * This allows the caller to tell whether a composite was triggered by
  39    * a paint that occurred after a call to TransactionId().
  40    */
  41   virtual TransactionId LastTransactionId() const = 0;
  42
  43   /**
  44    * Notify that all work (including asynchronous composites)
  45    * for a given transaction id has been completed.
  46    *
  47    * If the refresh driver has been suspended because
  48    * of having too many outstanding id's, then this may
  49    * resume it.
  50    */
  51   virtual void NotifyTransactionCompleted(TransactionId aTransactionId) = 0;
  52
  53   /**
  54    * Revoke a transaction id that isn't needed to track
  55    * completion of asynchronous work. This is similar
  56    * to NotifyTransactionCompleted except avoids
  57    * return ordering issues.
  58    */
  59   virtual void RevokeTransactionId(TransactionId aTransactionId) = 0;
  60
  61   /**
  62    * Stop waiting for pending transactions, if any.
  63    *
  64    * This is used when ClientLayerManager is assigning to another refresh
  65    * driver, and the current refresh driver may never receive transaction
  66    * completed notifications.
  67    */
  68   virtual void ClearPendingTransactions() = 0;
  69
  70   /**
  71    * Transaction id is usually initialized as 0, however when ClientLayerManager
  72    * switches to another refresh driver, completed transactions of the previous
  73    * refresh driver could be delivered and confuse the newly adopted refresh
  74    * driver. To prevent this situation, use this function to reset transaction
  75    * id to the last transaction id from previous refresh driver, so that all
  76    * completed transactions of previous refresh driver will be ignored.
  77    */
  78   virtual void ResetInitialTransactionId(TransactionId aTransactionId) = 0;
  79
  80   /**
  81    * Get the start time of the current refresh tick.
  82    */
  83   virtual mozilla::TimeStamp GetTransactionStart() = 0;
  84
  85   virtual VsyncId GetVsyncId() = 0;
  86
  87   virtual mozilla::TimeStamp GetVsyncStart() = 0;
  88 };
  89
  90 }  // namespace layers
  91 }  // namespace mozilla
  92
  93 #endif /* GFX_TRANSACTION_ID_ALLOCATOR_H */