Execute all GL commands up to the put offset reported by a flush.

gpu/command_buffer/client/cmd_buffer_helper.cc

 // 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.
 
 // This file contains the implementation of the command buffer helper class.
 
 #include "../client/cmd_buffer_helper.h"
 #include "../common/command_buffer.h"
 #include "../common/trace_event.h"
 
 namespace gpu {
 
 CommandBufferHelper::CommandBufferHelper(CommandBuffer* command_buffer)
     : command_buffer_(command_buffer),
       entries_(NULL),
       total_entry_count_(0),
       usable_entry_count_(0),
       token_(0),
-      last_token_read_(-1),
-      get_(0),
       put_(0),
       last_put_sent_(0) {
 }
 
 bool CommandBufferHelper::Initialize(int32 ring_buffer_size) {
   ring_buffer_ = command_buffer_->GetRingBuffer();
   if (!ring_buffer_.ptr)
     return false;
 
   CommandBuffer::State state = command_buffer_->GetState();
   entries_ = static_cast<CommandBufferEntry*>(ring_buffer_.ptr);
   int32 num_ring_buffer_entries = ring_buffer_size / sizeof(CommandBufferEntry);
   if (num_ring_buffer_entries > state.num_entries) {
     return false;
   }
 
   const int32 kJumpEntries =
       sizeof(cmd::Jump) / sizeof(*entries_);  // NOLINT
 
   total_entry_count_ = num_ring_buffer_entries;
   usable_entry_count_ = total_entry_count_ - kJumpEntries;
   put_ = state.put_offset;
-  SynchronizeState(state);
   return true;
 }
 
 CommandBufferHelper::~CommandBufferHelper() {
 }
 
 bool CommandBufferHelper::FlushSync() {
   last_put_sent_ = put_;
-  CommandBuffer::State state = command_buffer_->FlushSync(put_, get_);
-  SynchronizeState(state);
+  CommandBuffer::State state = command_buffer_->FlushSync(put_, get_offset());
   return state.error == error::kNoError;
 }
 
 void CommandBufferHelper::Flush() {
   last_put_sent_ = put_;
   command_buffer_->Flush(put_);
 }
 
 // Calls Flush() and then waits until the buffer is empty. Break early if the
 // error is set.
 bool CommandBufferHelper::Finish() {
   TRACE_EVENT0("gpu", "CommandBufferHelper::Finish");
   do {
     // Do not loop forever if the flush fails, meaning the command buffer reader
     // has shutdown.
     if (!FlushSync())
       return false;
-  } while (put_ != get_);
+  } while (put_ != get_offset());
 
   return true;
 }
 
 // Inserts a new token into the command stream. It uses an increasing value
 // scheme so that we don't lose tokens (a token has passed if the current token
 // value is higher than that token). Calls Finish() if the token value wraps,
 // which will be rare.
 int32 CommandBufferHelper::InsertToken() {
   // Increment token as 31-bit integer. Negative values are used to signal an
   // error.
   token_ = (token_ + 1) & 0x7FFFFFFF;
   cmd::SetToken& cmd = GetCmdSpace<cmd::SetToken>();
   cmd.Init(token_);
   if (token_ == 0) {
     TRACE_EVENT0("gpu", "CommandBufferHelper::InsertToken(wrapped)");
     // we wrapped
     Finish();
-    GPU_DCHECK_EQ(token_, last_token_read_);
+    GPU_DCHECK_EQ(token_, last_token_read());
   }
   return token_;
 }
 
 // Waits until the current token value is greater or equal to the value passed
 // in argument.
 void CommandBufferHelper::WaitForToken(int32 token) {
   TRACE_EVENT_IF_LONGER_THAN0(50, "gpu", "CommandBufferHelper::WaitForToken");
   // Return immediately if corresponding InsertToken failed.
   if (token < 0)
     return;
   if (token > token_) return;  // we wrapped
-  while (last_token_read_ < token) {
-    if (get_ == put_) {
+  while (last_token_read() < token) {
+    if (get_offset() == put_) {
       GPU_LOG(FATAL) << "Empty command buffer while waiting on a token.";
       return;
     }
     // Do not loop forever if the flush fails, meaning the command buffer reader
     // has shutdown.
     if (!FlushSync())
       return;
   }
 }
 
-void CommandBufferHelper::YieldScheduler() {
-  cmd::YieldScheduler& cmd = GetCmdSpace<cmd::YieldScheduler>();
-  cmd.Init();
-}
-
 // Waits for available entries, basically waiting until get >= put + count + 1.
 // It actually waits for contiguous entries, so it may need to wrap the buffer
 // around, adding a jump. Thus this function may change the value of put_. The
 // function will return early if an error occurs, in which case the available
 // space may not be available.
 void CommandBufferHelper::WaitForAvailableEntries(int32 count) {
   GPU_DCHECK(count < usable_entry_count_);
   if (put_ + count > usable_entry_count_) {
     // There's not enough room between the current put and the end of the
     // buffer, so we need to wrap. We will add a jump back to the start, but we
     // need to make sure get wraps first, actually that get is 1 or more (since
     // put will wrap to 0 after we add the jump).
     GPU_DCHECK_LE(1, put_);
-    if (get_ > put_ || get_ == 0) {
+    if (get_offset() > put_ || get_offset() == 0) {
       TRACE_EVENT0("gpu", "CommandBufferHelper::WaitForAvailableEntries");
-      while (get_ > put_ || get_ == 0) {
+      while (get_offset() > put_ || get_offset() == 0) {
         // Do not loop forever if the flush fails, meaning the command buffer
         // reader has shutdown.
         if (!FlushSync())
           return;
       }
     }
     // Insert a jump back to the beginning.
     cmd::Jump::Set(&entries_[put_], 0);
     put_ = 0;
   }
   if (AvailableEntries() < count) {
     TRACE_EVENT0("gpu", "CommandBufferHelper::WaitForAvailableEntries1");
     while (AvailableEntries() < count) {

[jbates, 2011/07/11 18:39:50]

Looks like this loop is no longer needed because of the call to Finish.

[apatrick_chromium, 2011/07/11 21:25:45]

It should actually be a FlushSync. Fixed.

       // Do not loop forever if the flush fails, meaning the command buffer
       // reader has shutdown.
-      if (!FlushSync())
+      if (!Finish())
         return;
     }
   }
   // Force a flush if the buffer is getting half full, or even earlier if the
   // reader is known to be idle.
   int32 pending =
       (put_ + usable_entry_count_ - last_put_sent_) % usable_entry_count_;
-  int32 limit = usable_entry_count_ / ((get_ == last_put_sent_) ? 16 : 2);
+  int32 limit = usable_entry_count_ /
+      ((get_offset() == last_put_sent_) ? 16 : 2);
   if (pending > limit) {
     Flush();
   }
 }
 
 CommandBufferEntry* CommandBufferHelper::GetSpace(uint32 entries) {
   WaitForAvailableEntries(entries);
   CommandBufferEntry* space = &entries_[put_];
   put_ += entries;
   GPU_DCHECK_LE(put_, usable_entry_count_);
   if (put_ == usable_entry_count_) {
     cmd::Jump::Set(&entries_[put_], 0);
     put_ = 0;
   }
   return space;
 }
 
 error::Error CommandBufferHelper::GetError() {
   CommandBuffer::State state = command_buffer_->GetState();
-  SynchronizeState(state);
   return static_cast<error::Error>(state.error);
 }
 
-void CommandBufferHelper::SynchronizeState(const CommandBuffer::State& state) {
-  get_ = state.get_offset;
-  last_token_read_ = state.token;
-}
-
 }  // namespace gpu