// Copyright (c) 2012 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.

#include "gpu/command_buffer/service/gpu_scheduler.h"

#include "base/bind.h"
#include "base/command_line.h"
#include "base/compiler_specific.h"
#include "base/message_loop/message_loop.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "gpu/command_buffer/service/logger.h"
#include "ui/gl/gl_bindings.h"
#include "ui/gl/gl_fence.h"
#include "ui/gl/gl_switches.h"

using ::base::SharedMemory;

namespace gpu {

GpuScheduler::GpuScheduler(CommandBufferServiceBase* command_buffer,
                           AsyncAPIInterface* handler,
                           gles2::GLES2Decoder* decoder)
    : command_buffer_(command_buffer),
      handler_(handler),
      decoder_(decoder),
      scheduled_(true),
      was_preempted_(false) {}

GpuScheduler::~GpuScheduler() {}

void GpuScheduler::PutChanged() {
  TRACE_EVENT1(
     "gpu", "GpuScheduler:PutChanged",
     "decoder", decoder_ ? decoder_->GetLogger()->GetLogPrefix() : "None");

  CommandBuffer::State state = command_buffer_->GetLastState();

  // If there is no parser, exit.
  if (!parser_.get()) {
    DCHECK_EQ(state.get_offset, command_buffer_->GetPutOffset());
    return;
  }

  parser_->set_put(command_buffer_->GetPutOffset());
  if (state.error != error::kNoError)
    return;

  base::TimeTicks begin_time(base::TimeTicks::Now());
  error::Error error = error::kNoError;
  if (decoder_)
    decoder_->BeginDecoding();
  while (!parser_->IsEmpty()) {
    if (IsPreempted())
      break;

    DCHECK(scheduled());

    error = parser_->ProcessCommands(CommandParser::kParseCommandsSlice);

    if (error == error::kDeferCommandUntilLater) {
      DCHECK(!scheduled());
      break;
    }

    // TODO(piman): various classes duplicate various pieces of state, leading
    // to needlessly complex update logic. It should be possible to simply
    // share the state across all of them.
    command_buffer_->SetGetOffset(static_cast<int32>(parser_->get()));

    if (error::IsError(error)) {
      command_buffer_->SetContextLostReason(decoder_->GetContextLostReason());
      command_buffer_->SetParseError(error);
      break;
    }

    if (!command_processed_callback_.is_null())
      command_processed_callback_.Run();

    if (!scheduled())
      break;
  }

  if (decoder_) {
    if (!error::IsError(error) && decoder_->WasContextLost()) {
      command_buffer_->SetContextLostReason(decoder_->GetContextLostReason());
      command_buffer_->SetParseError(error::kLostContext);
    }
    decoder_->EndDecoding();
    decoder_->AddProcessingCommandsTime(base::TimeTicks::Now() - begin_time);
  }
}

void GpuScheduler::SetScheduled(bool scheduled) {
  TRACE_EVENT2("gpu", "GpuScheduler:SetScheduled", "this", this, "scheduled",
               scheduled);
  if (scheduled_ == scheduled)
    return;
  scheduled_ = scheduled;
  if (!scheduling_changed_callback_.is_null())
    scheduling_changed_callback_.Run(scheduled);
}

bool GpuScheduler::HasPendingQueries() const {
  return (decoder_ && decoder_->HasPendingQueries());
}

void GpuScheduler::ProcessPendingQueries() {
  if (!decoder_)
    return;
  decoder_->ProcessPendingQueries(false);
}

void GpuScheduler::SetSchedulingChangedCallback(
    const SchedulingChangedCallback& callback) {
  scheduling_changed_callback_ = callback;
}

scoped_refptr<Buffer> GpuScheduler::GetSharedMemoryBuffer(int32 shm_id) {
  return command_buffer_->GetTransferBuffer(shm_id);
}

void GpuScheduler::set_token(int32 token) {
  command_buffer_->SetToken(token);
}

bool GpuScheduler::SetGetBuffer(int32 transfer_buffer_id) {
  scoped_refptr<Buffer> ring_buffer =
      command_buffer_->GetTransferBuffer(transfer_buffer_id);
  if (!ring_buffer.get()) {
    return false;
  }

  if (!parser_.get()) {
    parser_.reset(new CommandParser(handler_));
  }

  parser_->SetBuffer(
      ring_buffer->memory(), ring_buffer->size(), 0, ring_buffer->size());

  SetGetOffset(0);
  return true;
}

bool GpuScheduler::SetGetOffset(int32 offset) {
  if (parser_->set_get(offset)) {
    command_buffer_->SetGetOffset(static_cast<int32>(parser_->get()));
    return true;
  }
  return false;
}

int32 GpuScheduler::GetGetOffset() {
  return parser_->get();
}

void GpuScheduler::SetCommandProcessedCallback(
    const base::Closure& callback) {
  command_processed_callback_ = callback;
}

bool GpuScheduler::IsPreempted() {
  if (!preemption_flag_.get())
    return false;

  if (!was_preempted_ && preemption_flag_->IsSet()) {
    TRACE_COUNTER_ID1("gpu", "GpuScheduler::Preempted", this, 1);
    was_preempted_ = true;
  } else if (was_preempted_ && !preemption_flag_->IsSet()) {
    TRACE_COUNTER_ID1("gpu", "GpuScheduler::Preempted", this, 0);
    was_preempted_ = false;
  }

  return preemption_flag_->IsSet();
}

bool GpuScheduler::HasMoreIdleWork() const {
  return (decoder_ && decoder_->HasMoreIdleWork());
}

void GpuScheduler::PerformIdleWork() {
  if (!decoder_)
    return;
  decoder_->PerformIdleWork();
}

}  // namespace gpu