Added a way for sync point clients to issue out of order waits.

gpu/command_buffer/service/sync_point_manager.h

Index: gpu/command_buffer/service/sync_point_manager.h
diff --git a/gpu/command_buffer/service/sync_point_manager.h b/gpu/command_buffer/service/sync_point_manager.h
index cecf9febcb4dd17e094a8b83acff499262d3b394..97cdc6f7b7f14ed696bc9d8b34d3570598534dba 100644
--- a/gpu/command_buffer/service/sync_point_manager.h
+++ b/gpu/command_buffer/service/sync_point_manager.h
@@ -42,6 +42,7 @@ class GPU_EXPORT SyncPointOrderData
 
   uint32_t GenerateUnprocessedOrderNumber(SyncPointManager* sync_point_manager);
   void BeginProcessingOrderNumber(uint32_t order_num);
+  void PauseProcessingOrderNumber(uint32_t order_num);
   void FinishProcessingOrderNumber(uint32_t order_num);
 
   uint32_t processed_order_num() const {
@@ -59,6 +60,11 @@ class GPU_EXPORT SyncPointOrderData
     return current_order_num_;
   }
 
+  bool IsProcessingOrderNumber() {
+    DCHECK(processing_thread_checker_.CalledOnValidThread());
+    return !paused_ && current_order_num_ > processed_order_num();
+  }
+
  private:
   friend class base::RefCountedThreadSafe<SyncPointOrderData>;
   friend class SyncPointClientState;
@@ -97,6 +103,9 @@ class GPU_EXPORT SyncPointOrderData
   // Current IPC order number being processed (only used on processing thread).
   uint32_t current_order_num_;
 
+  // Whether or not the current order number is being processed or paused.
+  bool paused_;
+
   // This lock protects destroyed_, processed_order_num_,
   // unprocessed_order_num_, and order_fence_queue_. All order numbers (n) in
   // order_fence_queue_ must follow the invariant:
@@ -140,7 +149,6 @@ class GPU_EXPORT SyncPointClientState
  private:
   friend class base::RefCountedThreadSafe<SyncPointClientState>;
   friend class SyncPointClient;
-  friend class SyncPointClientWaiter;
   friend class SyncPointOrderData;
 
   struct ReleaseCallback {
@@ -213,11 +221,30 @@ class GPU_EXPORT SyncPointClient {
                          scoped_refptr<base::SingleThreadTaskRunner> runner,
                          const base::Closure& wait_complete_callback);
 
+  // Unordered waits are waits which do not occur within the global order number
+  // processing order (IE. Not between the corresponding
+  // SyncPointOrderData::BeginProcessingOrderNumber() and
+  // SyncPointOrderData::FinishProcessingOrderNumber() calls). Because fence
+  // sync releases must occur within a corresponding order number, these waits
+  // cannot deadlock because they can never depend on any fence sync releases.
+  // This is useful for IPC messages that may be processed out of order with
+  // respect to regular command buffer processing.
+  bool WaitOutOfOrder(SyncPointClientState* release_state,
+                      uint64_t release_count,
+                      const base::Closure& wait_complete_callback);
+
+  bool WaitOutOfOrderNonThreadSafe(
+      SyncPointClientState* release_state,
+      uint64_t release_count,
+      scoped_refptr<base::SingleThreadTaskRunner> runner,
+      const base::Closure& wait_complete_callback);
+
   void ReleaseFenceSync(uint64_t release);
 
  private:
   friend class SyncPointManager;
 
+  SyncPointClient();
   SyncPointClient(SyncPointManager* sync_point_manager,
                   scoped_refptr<SyncPointOrderData> order_data,
                   CommandBufferNamespace namespace_id,
@@ -236,32 +263,6 @@ class GPU_EXPORT SyncPointClient {
   DISALLOW_COPY_AND_ASSIGN(SyncPointClient);
 };
 
-// A SyncPointClientWaiter is a Sync Point Client which can only wait and on
-// fence syncs and not release any fence syncs itself. Because they cannot
-// release any fence syncs they do not need an associated order number since
-// deadlocks cannot happen. Note that it is important that this class does
-// not exist in the same execution context as a SyncPointClient, or else a
-// deadlock could occur. Basically, SyncPointClientWaiter::Wait() should never
-// be called between SyncPointOrderData::BeginProcessingOrderNumber() and
-// SyncPointOrderData::FinishProcessingOrderNumber() on the same thread.
-class GPU_EXPORT SyncPointClientWaiter {
- public:
-  SyncPointClientWaiter() {}
-  ~SyncPointClientWaiter() {}
-
-  bool Wait(SyncPointClientState* release_state,
-            uint64_t release_count,
-            const base::Closure& wait_complete_callback);
-
-  bool WaitNonThreadSafe(SyncPointClientState* release_state,
-                         uint64_t release_count,
-                         scoped_refptr<base::SingleThreadTaskRunner> runner,
-                         const base::Closure& wait_complete_callback);
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(SyncPointClientWaiter);
-};
-
 // This class manages the sync points, which allow cross-channel
 // synchronization.
 class GPU_EXPORT SyncPointManager {
@@ -275,6 +276,10 @@ class GPU_EXPORT SyncPointManager {
       CommandBufferNamespace namespace_id,
       uint64_t client_id);
 
+  // Creates a sync point client which cannot process order numbers but can only
+  // Wait out of order.
+  scoped_ptr<SyncPointClient> CreateSyncPointClientWaiter();
+
   // Finds the state of an already created sync point client.
   scoped_refptr<SyncPointClientState> GetSyncPointClientState(
     CommandBufferNamespace namespace_id, uint64_t client_id);