Rework FlushSync to return early if commands have been processed since the last update

BUG=80480
TEST=

Review URL: http://codereview.chromium.org/6883179

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@83442 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 48 insertions, 14 deletions

diff --git a/ppapi/c/dev/ppb_context_3d_trusted_dev.h b/ppapi/c/dev/ppb_context_3d_trusted_dev.h
index afc860f..ce4d8d6 100644
--- a/ppapi/c/dev/ppb_context_3d_trusted_dev.h
+++ b/ppapi/c/dev/ppb_context_3d_trusted_dev.h
@@ -11,9 +11,9 @@
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_stdint.h"
 
-#define PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_3 "PPB_Context3DTrusted(Dev);0.3"
+#define PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_4 "PPB_Context3DTrusted(Dev);0.4"
 #define PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE \
-    PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_3
+    PPB_CONTEXT_3D_TRUSTED_DEV_INTERFACE_0_4
 
 typedef enum {
   kNoError,
@@ -44,6 +44,11 @@ struct PP_Context3DTrustedState {
 
   // Error status.
   PPB_Context3DTrustedError error;
+
+  // Generation index of this state. The generation index is incremented every
+  // time a new state is retrieved from the command processor, so that
+  // consistency can be kept even if IPC messages are processed out-of-order.
+  uint32_t generation;
 };
 
 struct PPB_Context3DTrusted_Dev {
@@ -89,6 +94,13 @@ struct PPB_Context3DTrusted_Dev {
                                int32_t id,
                                int* shm_handle,
                                uint32_t* shm_size);
+
+  // Like FlushSync, but returns before processing commands if the get offset is
+  // different than last_known_get. Allows synchronization with the command
+  // processor without forcing immediate command execution.
+  struct PP_Context3DTrustedState (*FlushSyncFast)(PP_Resource context,
+                                                   int32_t put_offset,
+                                                   int32_t last_known_get);
 };
 
 #endif  // PPAPI_C_DEV_PPB_CONTEXT_3D_TRUSTED_DEV_H_
diff --git a/ppapi/proxy/ppapi_messages.h b/ppapi/proxy/ppapi_messages.h
index 32dfdf2..6bbd8bd 100644
--- a/ppapi/proxy/ppapi_messages.h
+++ b/ppapi/proxy/ppapi_messages.h
@@ -316,9 +316,10 @@ IPC_SYNC_MESSAGE_ROUTED1_1(PpapiHostMsg_PPBContext3D_GetState,
                            pp::proxy::HostResource /* context */,
                            gpu::CommandBuffer::State /* state */)
 
-IPC_SYNC_MESSAGE_ROUTED2_1(PpapiHostMsg_PPBContext3D_Flush,
+IPC_SYNC_MESSAGE_ROUTED3_1(PpapiHostMsg_PPBContext3D_Flush,
                            pp::proxy::HostResource /* context */,
                            int32 /* put_offset */,
+                           int32 /* last_known_get */,
                            gpu::CommandBuffer::State /* state */)
 
 IPC_MESSAGE_ROUTED2(PpapiHostMsg_PPBContext3D_AsyncFlush,
diff --git a/ppapi/proxy/ppb_context_3d_proxy.cc b/ppapi/proxy/ppb_context_3d_proxy.cc
index 396ccf6..fce162b 100644
--- a/ppapi/proxy/ppb_context_3d_proxy.cc
+++ b/ppapi/proxy/ppb_context_3d_proxy.cc
@@ -155,6 +155,7 @@ gpu::CommandBuffer::State GPUStateFromPPState(
   state.put_offset = s.put_offset;
   state.token = s.token;
   state.error = static_cast<gpu::error::Error>(s.error);
+  state.generation = s.generation;
   return state;
 }
 
@@ -181,7 +182,7 @@ class PepperCommandBuffer : public gpu::CommandBuffer {
   virtual gpu::Buffer GetRingBuffer();
   virtual State GetState();
   virtual void Flush(int32 put_offset);
-  virtual State FlushSync(int32 put_offset);
+  virtual State FlushSync(int32 put_offset, int32 last_known_get);
   virtual void SetGetOffset(int32 get_offset);
   virtual int32 CreateTransferBuffer(size_t size, int32 id_request);
   virtual int32 RegisterTransferBuffer(base::SharedMemory* shared_memory,
@@ -194,6 +195,7 @@ class PepperCommandBuffer : public gpu::CommandBuffer {
 
  private:
   bool Send(IPC::Message* msg);
+  void UpdateState(const gpu::CommandBuffer::State& state);
 
   int32 num_entries_;
   scoped_ptr<base::SharedMemory> ring_buffer_;
@@ -268,8 +270,10 @@ gpu::Buffer PepperCommandBuffer::GetRingBuffer() {
 gpu::CommandBuffer::State PepperCommandBuffer::GetState() {
   // Send will flag state with lost context if IPC fails.
   if (last_state_.error == gpu::error::kNoError) {
-    Send(new PpapiHostMsg_PPBContext3D_GetState(
-        INTERFACE_ID_PPB_CONTEXT_3D, resource_, &last_state_));
+    gpu::CommandBuffer::State state;
+    if (Send(new PpapiHostMsg_PPBContext3D_GetState(
+             INTERFACE_ID_PPB_CONTEXT_3D, resource_, &state)))
+      UpdateState(state);
   }
 
   return last_state_;
@@ -289,11 +293,19 @@ void PepperCommandBuffer::Flush(int32 put_offset) {
   Send(message);
 }
 
-gpu::CommandBuffer::State PepperCommandBuffer::FlushSync(int32 put_offset) {
-  // Send will flag state with lost context if IPC fails.
-  if (last_state_.error == gpu::error::kNoError) {
-    Send(new PpapiHostMsg_PPBContext3D_Flush(
-        INTERFACE_ID_PPB_CONTEXT_3D, resource_, put_offset, &last_state_));
+gpu::CommandBuffer::State PepperCommandBuffer::FlushSync(
+    int32 put_offset, int32 last_known_get) {
+  if (last_known_get == last_state_.get_offset) {
+    // Send will flag state with lost context if IPC fails.
+    if (last_state_.error == gpu::error::kNoError) {
+      gpu::CommandBuffer::State state;
+      if (Send(new PpapiHostMsg_PPBContext3D_Flush(
+              INTERFACE_ID_PPB_CONTEXT_3D, resource_, put_offset,
+              last_known_get, &state)))
+        UpdateState(state);
+    }
+  } else {
+    Flush(put_offset);
   }
 
   return last_state_;
@@ -400,6 +412,13 @@ bool PepperCommandBuffer::Send(IPC::Message* msg) {
   return false;
 }
 
+void PepperCommandBuffer::UpdateState(const gpu::CommandBuffer::State& state) {
+  // Handle wraparound. It works as long as we don't have more than 2B state
+  // updates in flight across which reordering occurs.
+  if (state.generation - last_state_.generation < 0x80000000U)
+    last_state_ = state;
+}
+
 Context3D::Context3D(const HostResource& resource)
     : PluginResource(resource),
       draw_(NULL),
@@ -571,9 +590,10 @@ void PPB_Context3D_Proxy::OnMsgGetState(const HostResource& context,
 
 void PPB_Context3D_Proxy::OnMsgFlush(const HostResource& context,
                                      int32 put_offset,
+                                     int32 last_known_get,
                                      gpu::CommandBuffer::State* state) {
-  PP_Context3DTrustedState pp_state =
-      ppb_context_3d_trusted()->FlushSync(context.host_resource(), put_offset);
+  PP_Context3DTrustedState pp_state = ppb_context_3d_trusted()->FlushSyncFast(
+      context.host_resource(), put_offset, last_known_get);
   *state = GPUStateFromPPState(pp_state);
 }
 
diff --git a/ppapi/proxy/ppb_context_3d_proxy.h b/ppapi/proxy/ppb_context_3d_proxy.h
index 117dbe0..3e2f953 100644
--- a/ppapi/proxy/ppb_context_3d_proxy.h
+++ b/ppapi/proxy/ppb_context_3d_proxy.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -100,6 +100,7 @@ class PPB_Context3D_Proxy : public InterfaceProxy {
                      gpu::CommandBuffer::State* state);
   void OnMsgFlush(const HostResource& context,
                   int32 put_offset,
+                  int32 last_known_get,
                   gpu::CommandBuffer::State* state);
   void OnMsgAsyncFlush(const HostResource& context,
                        int32 put_offset);