src/ui/scenic/lib/flatland/renderer/null_renderer.cc

// Copyright 2020 The Fuchsia 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 "src/ui/scenic/lib/flatland/renderer/null_renderer.h"

#include <lib/syslog/cpp/macros.h>
#include <zircon/pixelformat.h>

namespace flatland {

bool NullRenderer::RegisterTextureCollection(
    sysmem_util::GlobalBufferCollectionId collection_id,
    fuchsia::sysmem::Allocator_Sync* sysmem_allocator,
    fidl::InterfaceHandle<fuchsia::sysmem::BufferCollectionToken> token) {
  return RegisterCollection(collection_id, sysmem_allocator, std::move(token));
}

bool NullRenderer::RegisterRenderTargetCollection(
    sysmem_util::GlobalBufferCollectionId collection_id,
    fuchsia::sysmem::Allocator_Sync* sysmem_allocator,
    fidl::InterfaceHandle<fuchsia::sysmem::BufferCollectionToken> token) {
  return RegisterCollection(collection_id, sysmem_allocator, std::move(token));
}

bool NullRenderer::RegisterCollection(
    sysmem_util::GlobalBufferCollectionId collection_id,
    fuchsia::sysmem::Allocator_Sync* sysmem_allocator,
    fidl::InterfaceHandle<fuchsia::sysmem::BufferCollectionToken> token) {
  FX_DCHECK(collection_id != sysmem_util::kInvalidId);

  // Check for a null token here before we try to duplicate it to get the
  // vulkan token.
  if (!token.is_valid()) {
    FX_LOGS(ERROR) << "Token is invalid.";
    return false;
  }

  if (collection_map_.find(collection_id) != collection_map_.end()) {
    FX_LOGS(ERROR) << "Duplicate GlobalBufferCollectionID: " << collection_id;
    return false;
  }

  auto result = BufferCollectionInfo::New(sysmem_allocator, std::move(token));

  if (result.is_error()) {
    FX_LOGS(ERROR) << "Unable to register collection.";
    return false;
  }

  // Multiple threads may be attempting to read/write from |collection_map_| so we
  // lock this function here.
  // TODO(fxbug.dev/44335): Convert this to a lock-free structure.
  std::unique_lock<std::mutex> lock(lock_);
  collection_map_[collection_id] = std::move(result.value());
  return true;
}

void NullRenderer::DeregisterCollection(sysmem_util::GlobalBufferCollectionId collection_id) {
  // Multiple threads may be attempting to read/write from the various maps,
  // lock this function here.
  // TODO(fxbug.dev/44335): Convert this to a lock-free structure.
  std::unique_lock<std::mutex> lock(lock_);

  auto collection_itr = collection_map_.find(collection_id);

  // If the collection is not in the map, then there's nothing to do.
  if (collection_itr == collection_map_.end()) {
    return;
  }

  // Erase the sysmem collection from the map.
  collection_map_.erase(collection_id);

  // Erase the metadata. There may not actually be any metadata if the collection was
  // never validated, but there's no need to check as erasing a non-existent key is valid.
  collection_metadata_map_.erase(collection_id);
}

std::optional<BufferCollectionMetadata> NullRenderer::Validate(
    sysmem_util::GlobalBufferCollectionId collection_id) {
  // TODO(fxbug.dev/44335): Convert this to a lock-free structure. This is trickier than in the
  // other two cases for this class since we are mutating the buffer collection in this call. So we
  // can only convert this to a lock free structure if the elements in the map are changed to be
  // values only, or if we can guarantee that mutations on the elements only occur in a single
  // thread.
  std::unique_lock<std::mutex> lock(lock_);
  auto collection_itr = collection_map_.find(collection_id);

  // If the collection is not in the map, then it can't be validated.
  if (collection_itr == collection_map_.end()) {
    return std::nullopt;
  }

  // If there is already metadata, we can just return it instead of checking the allocation
  // status again. Once a buffer is allocated it won't be stop being allocated.
  auto metadata_itr = collection_metadata_map_.find(collection_id);
  if (metadata_itr != collection_metadata_map_.end()) {
    return metadata_itr->second;
  }

  // The collection should be allocated (i.e. all constraints set).
  auto& collection = collection_itr->second;
  if (!collection.BuffersAreAllocated()) {
    return std::nullopt;
  }

  // If the collection is in the map, and it's allocated, then we can return meta-data regarding
  // vmos and image constraints to the client.
  const auto& sysmem_info = collection.GetSysmemInfo();
  BufferCollectionMetadata result;
  result.vmo_count = sysmem_info.buffer_count;
  result.image_constraints = sysmem_info.settings.image_format_constraints;
  collection_metadata_map_[collection_id] = result;
  return result;
}

// Check that the buffer collections for each of the images passed in have been validated.
// DCHECK if they have not.
void NullRenderer::Render(const ImageMetadata& render_target,
                          const std::vector<Rectangle2D>& rectangles,
                          const std::vector<ImageMetadata>& images,
                          const std::vector<zx::event>& release_fences) {
  for (const auto& image : images) {
    auto collection_id = image.collection_id;
    FX_DCHECK(collection_id != sysmem_util::kInvalidId);

    // TODO(fxbug.dev/44335): Convert this to a lock-free structure.
    std::unique_lock<std::mutex> lock(lock_);
    auto metadata_itr = collection_metadata_map_.find(collection_id);
    FX_DCHECK(metadata_itr != collection_metadata_map_.end());
    auto metadata = metadata_itr->second;
    lock.release();

    // Make sure the image conforms to the constraints of the collection.
    FX_DCHECK(image.vmo_idx < metadata.vmo_count);
    FX_DCHECK(image.width <= metadata.image_constraints.max_coded_width);
    FX_DCHECK(image.height <= metadata.image_constraints.max_coded_height);
  }

  // Fire all of the release fences.
  for (auto& fence : release_fences) {
    fence.signal(0, ZX_EVENT_SIGNALED);
  }
}

}  // namespace flatland