// Copyright 2014 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 "media/capture/content/thread_safe_capture_oracle.h"

#include <stdint.h>
#include <utility>

#include "base/bind.h"
#include "base/bits.h"
#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "media/base/video_capture_types.h"
#include "media/base/video_frame.h"
#include "media/base/video_frame_metadata.h"
#include "media/base/video_util.h"
#include "ui/gfx/geometry/rect.h"

namespace media {

namespace {

// The target maximum amount of the buffer pool to utilize.  Actual buffer pool
// utilization is attenuated by this amount before being reported to the
// VideoCaptureOracle.  This value takes into account the maximum number of
// buffer pool buffers and a desired safety margin.
const int kTargetMaxPoolUtilizationPercent = 60;

}  // namespace

ThreadSafeCaptureOracle::ThreadSafeCaptureOracle(
    scoped_ptr<VideoCaptureDevice::Client> client,
    const VideoCaptureParams& params,
    bool enable_auto_throttling)
    : client_(std::move(client)),
      oracle_(base::TimeDelta::FromMicroseconds(static_cast<int64_t>(
                  1000000.0 / params.requested_format.frame_rate +
                  0.5 /* to round to nearest int */)),
              params.requested_format.frame_size,
              params.resolution_change_policy,
              enable_auto_throttling),
      params_(params) {}

ThreadSafeCaptureOracle::~ThreadSafeCaptureOracle() {
}

bool ThreadSafeCaptureOracle::ObserveEventAndDecideCapture(
    VideoCaptureOracle::Event event,
    const gfx::Rect& damage_rect,
    base::TimeTicks event_time,
    scoped_refptr<VideoFrame>* storage,
    CaptureFrameCallback* callback) {
  // Grab the current time before waiting to acquire the |lock_|.
  const base::TimeTicks capture_begin_time = base::TimeTicks::Now();

  base::AutoLock guard(lock_);

  if (!client_)
    return false;  // Capture is stopped.

  const bool should_capture =
      oracle_.ObserveEventAndDecideCapture(event, damage_rect, event_time);
  const gfx::Size visible_size = oracle_.capture_size();
  // TODO(miu): Clients should request exact padding, instead of this
  // memory-wasting hack to make frames that are compatible with all HW
  // encoders.  http://crbug.com/555911
  const gfx::Size coded_size(base::bits::Align(visible_size.width(), 16),
                             base::bits::Align(visible_size.height(), 16));

  scoped_ptr<media::VideoCaptureDevice::Client::Buffer> output_buffer(
      client_->ReserveOutputBuffer(coded_size,
                                   params_.requested_format.pixel_format,
                                   params_.requested_format.pixel_storage));
  // Get the current buffer pool utilization and attenuate it: The utilization
  // reported to the oracle is in terms of a maximum sustainable amount (not the
  // absolute maximum).
  const double attenuated_utilization =
      client_->GetBufferPoolUtilization() *
      (100.0 / kTargetMaxPoolUtilizationPercent);

  const char* event_name =
      (event == VideoCaptureOracle::kTimerPoll
           ? "poll"
           : (event == VideoCaptureOracle::kCompositorUpdate ? "gpu"
                                                             : "unknown"));

  // Consider the various reasons not to initiate a capture.
  if (should_capture && !output_buffer.get()) {
    TRACE_EVENT_INSTANT1("gpu.capture", "PipelineLimited",
                         TRACE_EVENT_SCOPE_THREAD, "trigger", event_name);
    oracle_.RecordWillNotCapture(attenuated_utilization);
    return false;
  } else if (!should_capture && output_buffer.get()) {
    if (event == VideoCaptureOracle::kCompositorUpdate) {
      // This is a normal and acceptable way to drop a frame. We've hit our
      // capture rate limit: for example, the content is animating at 60fps but
      // we're capturing at 30fps.
      TRACE_EVENT_INSTANT1("gpu.capture", "FpsRateLimited",
                           TRACE_EVENT_SCOPE_THREAD, "trigger", event_name);
    }
    return false;
  } else if (!should_capture && !output_buffer.get()) {
    // We decided not to capture, but we wouldn't have been able to if we wanted
    // to because no output buffer was available.
    TRACE_EVENT_INSTANT1("gpu.capture", "NearlyPipelineLimited",
                         TRACE_EVENT_SCOPE_THREAD, "trigger", event_name);
    return false;
  }

  const int frame_number = oracle_.RecordCapture(attenuated_utilization);
  TRACE_EVENT_ASYNC_BEGIN2("gpu.capture", "Capture", output_buffer.get(),
                           "frame_number", frame_number, "trigger", event_name);

  DCHECK_EQ(media::PIXEL_STORAGE_CPU, params_.requested_format.pixel_storage);
  *storage = VideoFrame::WrapExternalSharedMemory(
      params_.requested_format.pixel_format, coded_size,
      gfx::Rect(visible_size), visible_size,
      static_cast<uint8_t*>(output_buffer->data()),
      output_buffer->mapped_size(), base::SharedMemory::NULLHandle(), 0u,
      base::TimeDelta());
  if (!(*storage))
    return false;
  *callback =
      base::Bind(&ThreadSafeCaptureOracle::DidCaptureFrame, this, frame_number,
                 base::Passed(&output_buffer), capture_begin_time,
                 oracle_.estimated_frame_duration());
  return true;
}

gfx::Size ThreadSafeCaptureOracle::GetCaptureSize() const {
  base::AutoLock guard(lock_);
  return oracle_.capture_size();
}

void ThreadSafeCaptureOracle::UpdateCaptureSize(const gfx::Size& source_size) {
  base::AutoLock guard(lock_);
  VLOG(1) << "Source size changed to " << source_size.ToString();
  oracle_.SetSourceSize(source_size);
}

void ThreadSafeCaptureOracle::Stop() {
  base::AutoLock guard(lock_);
  client_.reset();
}

void ThreadSafeCaptureOracle::ReportError(
    const tracked_objects::Location& from_here,
    const std::string& reason) {
  base::AutoLock guard(lock_);
  if (client_)
    client_->OnError(from_here, reason);
}

void ThreadSafeCaptureOracle::DidCaptureFrame(
    int frame_number,
    scoped_ptr<VideoCaptureDevice::Client::Buffer> buffer,
    base::TimeTicks capture_begin_time,
    base::TimeDelta estimated_frame_duration,
    const scoped_refptr<VideoFrame>& frame,
    base::TimeTicks timestamp,
    bool success) {
  base::AutoLock guard(lock_);
  TRACE_EVENT_ASYNC_END2("gpu.capture", "Capture", buffer.get(), "success",
                         success, "timestamp", timestamp.ToInternalValue());

  if (oracle_.CompleteCapture(frame_number, success, &timestamp)) {
    TRACE_EVENT_INSTANT0("gpu.capture", "CaptureSucceeded",
                         TRACE_EVENT_SCOPE_THREAD);

    if (!client_)
      return;  // Capture is stopped.

    frame->metadata()->SetDouble(VideoFrameMetadata::FRAME_RATE,
                                 params_.requested_format.frame_rate);
    frame->metadata()->SetTimeTicks(VideoFrameMetadata::CAPTURE_BEGIN_TIME,
                                    capture_begin_time);
    frame->metadata()->SetTimeTicks(VideoFrameMetadata::CAPTURE_END_TIME,
                                    base::TimeTicks::Now());
    frame->metadata()->SetTimeDelta(VideoFrameMetadata::FRAME_DURATION,
                                    estimated_frame_duration);

    frame->AddDestructionObserver(
        base::Bind(&ThreadSafeCaptureOracle::DidConsumeFrame, this,
                   frame_number, frame->metadata()));

    client_->OnIncomingCapturedVideoFrame(std::move(buffer), frame, timestamp);
  }
}

void ThreadSafeCaptureOracle::DidConsumeFrame(
    int frame_number,
    const media::VideoFrameMetadata* metadata) {
  // Note: This function may be called on any thread by the VideoFrame
  // destructor.  |metadata| is still valid for read-access at this point.
  double utilization = -1.0;
  if (metadata->GetDouble(media::VideoFrameMetadata::RESOURCE_UTILIZATION,
                          &utilization)) {
    base::AutoLock guard(lock_);
    oracle_.RecordConsumerFeedback(frame_number, utilization);
  }
}

}  // namespace media