// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef GPU_COMMAND_BUFFER_SERVICE_SERVICE_TRANSFER_CACHE_H_
#define GPU_COMMAND_BUFFER_SERVICE_SERVICE_TRANSFER_CACHE_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <vector>

#include "base/containers/lru_cache.h"
#include "base/containers/span.h"
#include "base/functional/callback.h"
#include "base/functional/function_ref.h"
#include "base/gtest_prod_util.h"
#include "base/memory/memory_pressure_listener.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "base/trace_event/memory_dump_provider.h"
#include "cc/paint/image_transfer_cache_entry.h"
#include "cc/paint/transfer_cache_entry.h"
#include "gpu/command_buffer/common/discardable_handle.h"
#include "gpu/command_buffer/service/context_group.h"
#include "gpu/gpu_gles2_export.h"
#include "third_party/skia/include/core/SkImageInfo.h"
#include "third_party/skia/include/core/SkRefCnt.h"
#include "third_party/skia/include/core/SkYUVAInfo.h"

class GrDirectContext;

namespace gpu {

// ServiceTransferCache is a GPU process interface for retrieving cached entries
// from the transfer cache. These entries are populated by client calls to the
// ClientTransferCache or by an image decode accelerator task in the GPU
// process.
//
// In addition to access, the ServiceTransferCache is also responsible for
// unlocking and deleting entries when no longer needed, as well as enforcing
// cache limits. If the cache exceeds its specified limits, unlocked transfer
// cache entries may be deleted.
class GPU_GLES2_EXPORT ServiceTransferCache
    : public base::trace_event::MemoryDumpProvider {
 public:
  struct GPU_GLES2_EXPORT EntryKey {
    EntryKey(int decoder_id,
             cc::TransferCacheEntryType entry_type,
             uint64_t entry_id);
    int decoder_id;
    cc::TransferCacheEntryType entry_type;
    uint64_t entry_id;
  };

  ServiceTransferCache(const GpuPreferences& preferences,
                       base::RepeatingClosure flush_callback);

  ServiceTransferCache(const ServiceTransferCache&) = delete;
  ServiceTransferCache& operator=(const ServiceTransferCache&) = delete;

  ~ServiceTransferCache() override;

  bool CreateLockedEntry(const EntryKey& key,
                         ServiceDiscardableHandle handle,
                         GrDirectContext* context,
                         skgpu::graphite::Recorder* graphite_recorder,
                         base::span<uint8_t> data);
  void CreateLocalEntry(const EntryKey& key,
                        std::unique_ptr<cc::ServiceTransferCacheEntry> entry);
  bool UnlockEntry(const EntryKey& key);
  bool DeleteEntry(const EntryKey& key);
  cc::ServiceTransferCacheEntry* GetEntry(const EntryKey& key);
  void DeleteAllEntriesForDecoder(int decoder_id);

  // Memory coordinator interface:
  // Triggers immediate eviction of transfer cache entries down to
  // `memory_limit`.
  void OnReleaseMemory(int memory_limit);
  // Updates the target cache size limit non-destructively without forcing
  // immediate eviction.
  void OnUpdateMemoryLimit(int memory_limit);

  // base::trace_event::MemoryDumpProvider implementation.
  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                    base::trace_event::ProcessMemoryDump* pmd) override;

  // Test-only functions:
  void SetCacheSizeLimitForTesting(size_t cache_size_limit) {
    max_cache_size_limit_ = cache_size_limit;
    cache_size_limit_ = cache_size_limit;
    EnforceLimits();
  }
  void SetMaxCacheEntriesForTesting(size_t max_cache_entries) {
    max_cache_entries_ = max_cache_entries;
    EnforceLimits();
  }
  size_t cache_size_for_testing() const { return total_size_; }
  size_t entries_count_for_testing() const { return entries_.size(); }

 private:
  FRIEND_TEST_ALL_PREFIXES(ServiceTransferCacheTest, PurgeEntryOnTimer);

  struct CacheEntryInternal {
    CacheEntryInternal(std::optional<ServiceDiscardableHandle> handle,
                       std::unique_ptr<cc::ServiceTransferCacheEntry> entry);
    CacheEntryInternal(CacheEntryInternal&& other);
    CacheEntryInternal& operator=(CacheEntryInternal&& other);
    ~CacheEntryInternal();
    std::optional<ServiceDiscardableHandle> handle;
    std::unique_ptr<cc::ServiceTransferCacheEntry> entry;
    base::TimeTicks last_use = base::TimeTicks::Now();

    // For metrics.
    uint32_t num_reuse = 0u;
    base::TimeDelta max_last_use_delta;
  };

  struct EntryKeyComp {
    bool operator()(const EntryKey& lhs, const EntryKey& rhs) const {
      if (lhs.decoder_id != rhs.decoder_id)
        return lhs.decoder_id < rhs.decoder_id;
      if (lhs.entry_type != rhs.entry_type)
        return lhs.entry_type < rhs.entry_type;
      return lhs.entry_id < rhs.entry_id;
    }
  };

  using EntryCache = base::LRUCache<EntryKey, CacheEntryInternal, EntryKeyComp>;

  void EnforceLimits();
  void MaybePostPruneOldEntries();
  void PruneOldEntries();
  // Helper to iterate through entries from least recently used to most
  // recently used and erase them until `should_stop` returns true. Returns
  // number of entries removed.
  int RemoveOldEntriesUntil(
      base::FunctionRef<bool(EntryCache::reverse_iterator)> should_stop);

  template <typename Iterator>
  Iterator ForceDeleteEntry(Iterator it);

  const base::RepeatingClosure flush_callback_;

  EntryCache entries_;

  // Total size of all |entries_|. The same as summing
  // GpuDiscardableEntry::size for each entry.
  size_t total_size_ = 0;
  // Total size of all |entries_| of TransferCacheEntryType::kImage.
  size_t total_image_size_ = 0;
  // Number of |entries_| of TransferCacheEntryType::kImage.
  int total_image_count_ = 0;

  // The baseline limit above which the cache will start evicting resources.
  // Constant during normal execution, modified only by
  // SetCacheSizeLimitForTesting().
  size_t max_cache_size_limit_;

  // The limit above which the cache will start evicting resources.
  size_t cache_size_limit_;

  // The max number of entries we will hold in the cache.
  size_t max_cache_entries_;

  bool request_post_prune_old_entries_while_pending_ = false;
  base::OneShotTimer prune_old_entries_timer_;
};

}  // namespace gpu

#endif  // GPU_COMMAND_BUFFER_SERVICE_SERVICE_TRANSFER_CACHE_H_