// 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.

#include "gpu/command_buffer/client/mapped_memory.h"

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

#include <algorithm>
#include <functional>

#include "base/atomic_sequence_num.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/numerics/checked_math.h"
#include "base/numerics/safe_conversions.h"
#include "base/strings/stringprintf.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/trace_event/memory_dump_manager.h"
#include "base/trace_event/trace_event.h"
#include "gpu/command_buffer/client/cmd_buffer_helper.h"
#include "gpu/command_buffer/client/shared_memory_limits.h"
#include "gpu/command_buffer/common/buffer.h"

namespace gpu {
namespace {

// Generates process-unique IDs to use for tracing a MappedMemoryManager's
// chunks.
base::AtomicSequenceNumber g_next_mapped_memory_manager_tracing_id;

}  // namespace

MemoryChunk::MemoryChunk(int32_t shm_id,
                         scoped_refptr<gpu::Buffer> shm,
                         CommandBufferHelper* helper)
    : shm_id_(shm_id),
      shm_(shm),
      allocator_(shm->size(), helper, shm->memory()) {}

MemoryChunk::~MemoryChunk() = default;

MappedMemoryManager::MappedMemoryManager(CommandBufferHelper* helper,
                                         size_t unused_memory_reclaim_limit)
    : chunk_size_multiple_(FencedAllocator::kAllocAlignment),
      helper_(helper),
      allocated_memory_(0),
      max_free_bytes_(unused_memory_reclaim_limit),
      max_allocated_bytes_(SharedMemoryLimits::kNoLimit),
      tracing_id_(g_next_mapped_memory_manager_tracing_id.GetNext()) {
}

MappedMemoryManager::~MappedMemoryManager() {
  helper_->OrderingBarrier();
  CommandBuffer* cmd_buf = helper_->command_buffer();
  for (auto& chunk : chunks_) {
    cmd_buf->DestroyTransferBuffer(chunk->shm_id());
  }
}

void* MappedMemoryManager::Alloc(unsigned int size,
                                 int32_t* shm_id,
                                 unsigned int* shm_offset) {
  DCHECK(shm_id);
  DCHECK(shm_offset);
  if (size <= allocated_memory_) {
    size_t total_bytes_in_use = 0;
    // See if any of the chunks can satisfy this request.
    for (auto& chunk : chunks_) {
      chunk->FreeUnused();
      total_bytes_in_use += chunk->bytes_in_use();
      if (chunk->GetLargestFreeSizeWithoutWaiting() >= size) {
        void* mem = chunk->Alloc(size);
        DCHECK(mem);
        *shm_id = chunk->shm_id();
        *shm_offset = chunk->GetOffset(mem);
        return mem;
      }
    }

    // If there is a memory limit being enforced and total free
    // memory (allocated_memory_ - total_bytes_in_use) is larger than
    // the limit try waiting.
    if (max_free_bytes_ != SharedMemoryLimits::kNoLimit &&
        (allocated_memory_ - total_bytes_in_use) >= max_free_bytes_) {
      TRACE_EVENT0("gpu", "MappedMemoryManager::Alloc::wait");
      for (auto& chunk : chunks_) {
        if (chunk->GetLargestFreeSizeWithWaiting() >= size) {
          void* mem = chunk->Alloc(size);
          DCHECK(mem);
          *shm_id = chunk->shm_id();
          *shm_offset = chunk->GetOffset(mem);
          return mem;
        }
      }
    }
  }

  if (max_allocated_bytes_ != SharedMemoryLimits::kNoLimit &&
      (allocated_memory_ + size) > max_allocated_bytes_) {
    return nullptr;
  }

  // Make a new chunk to satisfy the request.
  CommandBuffer* cmd_buf = helper_->command_buffer();
  base::CheckedNumeric<uint32_t> chunk_size = size;
  chunk_size = (size + chunk_size_multiple_ - 1) & ~(chunk_size_multiple_ - 1);
  uint32_t safe_chunk_size = 0;
  if (!chunk_size.AssignIfValid(&safe_chunk_size))
    return nullptr;

  int32_t id = -1;
  scoped_refptr<gpu::Buffer> shm =
      cmd_buf->CreateTransferBuffer(safe_chunk_size, &id);
  if (id  < 0)
    return nullptr;
  DCHECK(shm.get());
  MemoryChunk* mc = new MemoryChunk(id, shm, helper_);
  allocated_memory_ += mc->GetSize();
  chunks_.push_back(base::WrapUnique(mc));
  void* mem = mc->Alloc(size);
  DCHECK(mem);
  *shm_id = mc->shm_id();
  *shm_offset = mc->GetOffset(mem);
  return mem;
}

void MappedMemoryManager::Free(void* pointer) {
  for (auto& chunk : chunks_) {
    if (chunk->IsInChunk(pointer)) {
      chunk->Free(pointer);
      return;
    }
  }
  NOTREACHED();
}

void MappedMemoryManager::FreePendingToken(void* pointer, int32_t token) {
  for (auto& chunk : chunks_) {
    if (chunk->IsInChunk(pointer)) {
      chunk->FreePendingToken(pointer, token);
      return;
    }
  }
  NOTREACHED();
}

void MappedMemoryManager::FreeUnused() {
  CommandBuffer* cmd_buf = helper_->command_buffer();
  MemoryChunkVector::iterator iter = chunks_.begin();
  while (iter != chunks_.end()) {
    MemoryChunk* chunk = (*iter).get();
    chunk->FreeUnused();
    if (chunk->bytes_in_use() == 0u) {
      if (chunk->InUseOrFreePending())
        helper_->OrderingBarrier();
      cmd_buf->DestroyTransferBuffer(chunk->shm_id());
      allocated_memory_ -= chunk->GetSize();
      iter = chunks_.erase(iter);
    } else {
      ++iter;
    }
  }
}

bool MappedMemoryManager::OnMemoryDump(
    const base::trace_event::MemoryDumpArgs& args,
    base::trace_event::ProcessMemoryDump* pmd) {
  using base::trace_event::MemoryAllocatorDump;
  using base::trace_event::MemoryDumpLevelOfDetail;

  if (args.level_of_detail == MemoryDumpLevelOfDetail::BACKGROUND) {
    std::string dump_name =
        base::StringPrintf("gpu/mapped_memory/manager_%d", tracing_id_);
    MemoryAllocatorDump* dump = pmd->CreateAllocatorDump(dump_name);
    dump->AddScalar(MemoryAllocatorDump::kNameSize,
                    MemoryAllocatorDump::kUnitsBytes, allocated_memory_);

    // Early out, no need for more detail in a BACKGROUND dump.
    return true;
  }

  const uint64_t tracing_process_id =
      base::trace_event::MemoryDumpManager::GetInstance()
          ->GetTracingProcessId();
  for (const auto& chunk : chunks_) {
    std::string dump_name = base::StringPrintf(
        "gpu/mapped_memory/manager_%d/chunk_%d", tracing_id_, chunk->shm_id());
    MemoryAllocatorDump* dump = pmd->CreateAllocatorDump(dump_name);

    dump->AddScalar(MemoryAllocatorDump::kNameSize,
                    MemoryAllocatorDump::kUnitsBytes, chunk->GetSize());
    dump->AddScalar("free_size", MemoryAllocatorDump::kUnitsBytes,
                    chunk->GetFreeSize());

    auto shared_memory_guid = chunk->shared_memory()->backing()->GetGUID();
    const int kImportance = 2;
    if (!shared_memory_guid.is_empty()) {
      pmd->CreateSharedMemoryOwnershipEdge(dump->guid(), shared_memory_guid,
                                           kImportance);
    } else {
      auto guid = GetBufferGUIDForTracing(tracing_process_id, chunk->shm_id());
      pmd->CreateSharedGlobalAllocatorDump(guid);
      pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
    }
  }

  return true;
}

FencedAllocator::State MappedMemoryManager::GetPointerStatusForTest(
    void* pointer,
    int32_t* token_if_pending) {
  for (auto& chunk : chunks_) {
    if (chunk->IsInChunk(pointer)) {
      return chunk->GetPointerStatusForTest(pointer, token_if_pending);
    }
  }
  return FencedAllocator::FREE;
}

void ScopedMappedMemoryPtr::Release() {
  if (buffer_) {
    mapped_memory_manager_->FreePendingToken(buffer_, helper_->InsertToken());
    buffer_ = nullptr;
    size_ = 0;
    shm_id_ = 0;
    shm_offset_ = 0;

    if (flush_after_release_)
      helper_->CommandBufferHelper::Flush();
  }
}

void ScopedMappedMemoryPtr::Reset(uint32_t new_size) {
  Release();

  if (new_size) {
    buffer_ = mapped_memory_manager_->Alloc(new_size, &shm_id_, &shm_offset_);
    size_ = buffer_ ? new_size : 0;
  }
}

}  // namespace gpu