commonlibrary_memory_utils/README_zh.md

# The Part of Memory Base Libraries

-   [Introduction](#section_introduction)
-   [Architecture](#section_architecture)
-   [Directory Structure](#section_catalogue)
-   [Memory Base Libraries](#section_libraries)
    -   [libdmabufheap system library](#section_libdmabufheap)
    -   [libmeminfo system library (in planning)](#section_libmeminfo)
    -   [libmemleak system library (in planning)](#section_libmemleak)
    -   [libpurgeable system library (in planning)](#section_libpurgeable)
    -   [libspeculative system library (in planning)](#section_libspeculative)
-   [Usage Guidelines](#section_usage)
-   [Repositories Involved](#section_projects)

## Introduction<a name="section_introduction"></a>

The part of *Memory base libraries* belongs to the subsystem named *Utils Subsystem*. It provides the system library for upper-layer services to operate memory, ensuring the stability of upper-layer services.

## Architecture<a name="section_architecture"></a>

![](figures/en-us_image_fwk.png)

**Figure  1** Memory Base Libraries architecture

## Directory Structure<a name="section_catalogue"></a>

```
/utils/memory
├── libdmabufheap           # DMA (Direct Memory Access) memory allocation system library
│   ├── include             # DMA memory allocation system library header directory
│   ├── src                 # DMA memory allocation system library source directory
│   └── test                # DMA memory allocation system library usecase directory
├── libmeminfo              # Memory footprint management library
├── libmemleak              # Memory leak detection library
├── libpurgeable            # Purgeable memory management library
└── libspeculative          # Speculative memory management library
```

## Memory Base Libraries<a name="section_libraries"></a>

*Memory base libraries* is a component of the system library that integrates memory operations and manages them in a unified manner.

### libdmabufheap system library<a name="section_libdmabufheap"></a>

The memory system library provides interfaces for services to allocate and share shared memory. By allocating and sharing memory between hardware devices and user space, zero-copy memory between devices and processes is implemented to improve execution efficiency.

### libmeminfo system library (in planning)<a name="section_libmeminfo"></a>

It provides interfaces for memory usage queries. It is mainly used by memory footprint management service(hidumper) and low-memory killing service(lmks).

### libmemleak system library (in planning)<a name="section_libmemleak"></a>

It cooperates with malloc_debug to detect memory leaks of native heap.

### libpurgeable system library (in planning)<a name="section_libpurgeable"></a>

It provides management interfaces for discardable-type memory. It is mainly used by graphics and image codec libraries.

### libspeculative system library (in planning)<a name="section_libspeculative"></a>

It provides management interfaces for speculative-type memory. It is mainly used by system services for data pre-loading.

## Usage Guidelines<a name="section_usage"></a>

System developers can add or remove this part by configuring the product definition JSON file under **/productdefine/common/products** to enable or disable this part:

` "utils:utils_memory":{} `

## Repositories Involved<a name="section_projects"></a>

[utils](https://gitee.com/openharmony/utils)