runtime/Memory.h

/*
 * Copyright (C) 2017 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 ANDROID_FRAMEWORKS_ML_NN_RUNTIME_MEMORY_H
#define ANDROID_FRAMEWORKS_ML_NN_RUNTIME_MEMORY_H

#include "HalInterfaces.h"
#include "NeuralNetworks.h"
#include "Utils.h"

#include <android-base/macros.h>
#include <cutils/native_handle.h>
#include <sys/mman.h>
#include <vndk/hardware_buffer.h>
#include <memory>
#include <mutex>
#include <unordered_map>
#include <utility>
#include <vector>

namespace android {
namespace nn {

class ExecutionBurstController;
class ModelBuilder;

// Represents a memory region.
class Memory {
    // Disallow copy and assign to prevent slicing
    DISALLOW_COPY_AND_ASSIGN(Memory);

   public:
    // Custom destructor to notify any ExecutionBurstControllers currently using
    // this memory that it is being freed.
    virtual ~Memory();

    const hal::hidl_memory& getHidlMemory() const { return kHidlMemory; }

    virtual bool validateSize(uint32_t offset, uint32_t length) const;

    // Unique key representing this memory object.
    intptr_t getKey() const;

    // Marks a burst object as currently using this memory. When this
    // memory object is destroyed, it will automatically free this memory from
    // the bursts' memory cache.
    void usedBy(const std::shared_ptr<ExecutionBurstController>& burst) const;

   protected:
    Memory(hal::hidl_memory memory);

    // The hidl_memory handle for this shared memory.  We will pass this value when
    // communicating with the drivers.
    const hal::hidl_memory kHidlMemory;

   private:
    mutable std::mutex mMutex;
    // mUsedBy is essentially a set of burst objects which use this Memory
    // object. However, std::weak_ptr does not have comparison operations nor a
    // std::hash implementation. This is because it is either a valid pointer
    // (non-null) if the shared object is still alive, or it is null if the
    // object has been freed. To circumvent this, mUsedBy is a map with the raw
    // pointer as the key and the weak_ptr as the value.
    mutable std::unordered_map<const ExecutionBurstController*,
                               std::weak_ptr<ExecutionBurstController>>
            mUsedBy;
};

class MemoryAshmem : public Memory {
   public:
    // Creates a memory object containing a new android shared memory ("ashmem")
    // object of the size specified in bytes. Because this ashmem region can be
    // shared with and accessed by one or more driver processes, MemoryAshmem
    // has shared ownership over the ashmem region.
    //
    // On success, returns ANEURALNETWORKS_NO_ERROR and a memory object.
    // On error, returns the appropriate NNAPI error code and nullptr.
    static std::pair<int, std::unique_ptr<MemoryAshmem>> create(uint32_t size);

    // Get a pointer to the ashmem region of memory. The returned pointer is
    // valid for the lifetime of the MemoryAshmem object. This call always
    // returns non-null because it was validated during MemoryAshmem::create.
    uint8_t* getPointer() const;

    // prefer using MemoryAshmem::create
    MemoryAshmem(sp<hal::IMemory> mapped, hal::hidl_memory memory);

   private:
    const sp<hal::IMemory> kMappedMemory;
};

class MemoryFd : public Memory {
   public:
    // Create a memory object based on input size, prot, and fd that can be sent
    // across HIDL. This function duplicates the provided fd, and owns the
    // duplicate.
    //
    // On success, returns ANEURALNETWORKS_NO_ERROR and a memory object.
    // On error, returns the appropriate NNAPI error code and nullptr.
    static std::pair<int, std::unique_ptr<MemoryFd>> create(size_t size, int prot, int fd,
                                                            size_t offset);

    // prefer using MemoryFd::create
    MemoryFd(hal::hidl_memory memory);
};

class MemoryAHWB : public Memory {
   public:
    // Create a memory object to keep track of (but not take ownership of) the
    // provided AHardwareBuffer handle.
    //
    // On success, returns ANEURALNETWORKS_NO_ERROR and a memory object.
    // On error, returns the appropriate NNAPI error code and nullptr.
    static std::pair<int, std::unique_ptr<MemoryAHWB>> create(const AHardwareBuffer& ahwb);

    // validateSize should only be called for blob mode AHardwareBuffer.
    // Calling it on non-blob mode AHardwareBuffer will result in an error.
    // TODO(miaowang): consider separate blob and non-blob into different classes.
    bool validateSize(uint32_t offset, uint32_t length) const override;

    // prefer using MemoryAHWB::create
    MemoryAHWB(const AHardwareBuffer_Desc& desc, hal::hidl_memory memory);

   private:
    const bool kBlobMode;
};

// A utility class to accumulate mulitple Memory objects and assign each
// a distinct index number, starting with 0.
//
// The user of this class is responsible for avoiding concurrent calls
// to this class from multiple threads.
class MemoryTracker {
   private:
    // The vector of Memory pointers we are building.
    std::vector<const Memory*> mMemories;
    // A faster way to see if we already have a memory than doing find().
    std::unordered_map<const Memory*, uint32_t> mKnown;

   public:
    // Adds the memory, if it does not already exists.  Returns its index.
    // The memories should survive the tracker.
    uint32_t add(const Memory* memory);
    // Returns the number of memories contained.
    uint32_t size() const { return static_cast<uint32_t>(mKnown.size()); }
    // Returns the ith memory.
    const Memory* operator[](size_t i) const { return mMemories[i]; }
    // Iteration
    auto begin() { return mMemories.begin(); }
    auto end() { return mMemories.end(); }
    auto begin() const { return mMemories.begin(); }
    auto end() const { return mMemories.end(); }
};

}  // namespace nn
}  // namespace android

#endif  // ANDROID_FRAMEWORKS_ML_NN_RUNTIME_MEMORY_H