runtime/gc/space/image_space.h

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ART_RUNTIME_GC_SPACE_IMAGE_SPACE_H_
#define ART_RUNTIME_GC_SPACE_IMAGE_SPACE_H_

#include "gc/accounting/space_bitmap.h"
#include "runtime.h"
#include "space.h"

namespace art {

class OatFile;

namespace gc {
namespace space {

// An image space is a space backed with a memory mapped image.
class ImageSpace : public MemMapSpace {
 public:
  SpaceType GetType() const {
    return kSpaceTypeImageSpace;
  }

  // Create a Space from an image file for a specified instruction
  // set. Cannot be used for future allocation or collected.
  //
  // Create also opens the OatFile associated with the image file so
  // that it be contiguously allocated with the image before the
  // creation of the alloc space. The ReleaseOatFile will later be
  // used to transfer ownership of the OatFile to the ClassLinker when
  // it is initialized.
  static ImageSpace* Create(const char* image,
                            InstructionSet image_isa,
                            bool secondary_image,
                            std::string* error_msg)
      SHARED_REQUIRES(Locks::mutator_lock_);

  // Reads the image header from the specified image location for the
  // instruction set image_isa or dies trying.
  static ImageHeader* ReadImageHeaderOrDie(const char* image_location,
                                           InstructionSet image_isa);

  // Reads the image header from the specified image location for the
  // instruction set image_isa. Returns null on failure, with
  // reason in error_msg.
  static ImageHeader* ReadImageHeader(const char* image_location,
                                      InstructionSet image_isa,
                                      std::string* error_msg);

  // Give access to the OatFile.
  const OatFile* GetOatFile() const;

  // Releases the OatFile from the ImageSpace so it can be transfer to
  // the caller, presumably the OatFileManager.
  std::unique_ptr<const OatFile> ReleaseOatFile();

  void VerifyImageAllocations()
      SHARED_REQUIRES(Locks::mutator_lock_);

  const ImageHeader& GetImageHeader() const {
    return *reinterpret_cast<ImageHeader*>(Begin());
  }

  // Actual filename where image was loaded from.
  // For example: /data/dalvik-cache/arm/system@framework@boot.art
  const std::string GetImageFilename() const {
    return GetName();
  }

  // Symbolic location for image.
  // For example: /system/framework/boot.art
  const std::string GetImageLocation() const {
    return image_location_;
  }

  accounting::ContinuousSpaceBitmap* GetLiveBitmap() const OVERRIDE {
    return live_bitmap_.get();
  }

  accounting::ContinuousSpaceBitmap* GetMarkBitmap() const OVERRIDE {
    // ImageSpaces have the same bitmap for both live and marked. This helps reduce the number of
    // special cases to test against.
    return live_bitmap_.get();
  }

  void Dump(std::ostream& os) const;

  // Sweeping image spaces is a NOP.
  void Sweep(bool /* swap_bitmaps */, size_t* /* freed_objects */, size_t* /* freed_bytes */) {
  }

  bool CanMoveObjects() const OVERRIDE {
    return false;
  }

  // Returns the filename of the image corresponding to
  // requested image_location, or the filename where a new image
  // should be written if one doesn't exist. Looks for a generated
  // image in the specified location and then in the dalvik-cache.
  //
  // Returns true if an image was found, false otherwise.
  static bool FindImageFilename(const char* image_location,
                                InstructionSet image_isa,
                                std::string* system_location,
                                bool* has_system,
                                std::string* data_location,
                                bool* dalvik_cache_exists,
                                bool* has_data,
                                bool *is_global_cache);

  // Return the end of the image which includes non-heap objects such as ArtMethods and ArtFields.
  uint8_t* GetImageEnd() const {
    return Begin() + GetImageHeader().GetImageSize();
  }

  // Return the start of the associated oat file.
  uint8_t* GetOatFileBegin() const {
    return GetImageHeader().GetOatFileBegin();
  }

  // Return the end of the associated oat file.
  uint8_t* GetOatFileEnd() const {
    return GetImageHeader().GetOatFileEnd();
  }

 protected:
  // Tries to initialize an ImageSpace from the given image path,
  // returning null on error.
  //
  // If validate_oat_file is false (for /system), do not verify that
  // image's OatFile is up-to-date relative to its DexFile
  // inputs. Otherwise (for /data), validate the inputs and generate
  // the OatFile in /data/dalvik-cache if necessary.
  static ImageSpace* Init(const char* image_filename, const char* image_location,
                          bool validate_oat_file, std::string* error_msg)
      SHARED_REQUIRES(Locks::mutator_lock_);

  OatFile* OpenOatFile(const char* image, std::string* error_msg) const
      SHARED_REQUIRES(Locks::mutator_lock_);

  bool ValidateOatFile(std::string* error_msg) const
      SHARED_REQUIRES(Locks::mutator_lock_);

  friend class Space;

  static Atomic<uint32_t> bitmap_index_;

  std::unique_ptr<accounting::ContinuousSpaceBitmap> live_bitmap_;

  ImageSpace(const std::string& name,
             const char* image_location,
             MemMap* mem_map,
             accounting::ContinuousSpaceBitmap* live_bitmap,
             uint8_t* end,
             MemMap* shadow_map = nullptr);

  // The OatFile associated with the image during early startup to
  // reserve space contiguous to the image. It is later released to
  // the ClassLinker during it's initialization.
  std::unique_ptr<OatFile> oat_file_;

  // There are times when we need to find the boot image oat file. As
  // we release ownership during startup, keep a non-owned reference.
  const OatFile* oat_file_non_owned_;

  const std::string image_location_;

  // A MemMap reserving the space of the bitmap "shadow," so that we don't allocate into it. Only
  // used in the multi-image case.
  std::unique_ptr<MemMap> shadow_map_;

 private:
  DISALLOW_COPY_AND_ASSIGN(ImageSpace);
};

}  // namespace space
}  // namespace gc
}  // namespace art

#endif  // ART_RUNTIME_GC_SPACE_IMAGE_SPACE_H_