Project Structure and Dependencies

Relevant source files

• Cargo.toml

This document details the crate configuration, external dependencies, and organizational structure of the flatten_objects library. It explains how the project is configured for the ArceOS ecosystem and its role as a no_std compatible container library.

For implementation details of the core data structures, see Internal Data Structures. For build and testing procedures, see Building and Testing.

Crate Configuration and Metadata

The flatten_objects crate is configured as a library package targeting resource-constrained environments. The crate metadata defines its purpose as a numbered object container with unique ID assignment capabilities.

Project Metadata

The crate is categorized under no-std and data-structures, indicating its suitability for embedded and kernel development environments where the standard library is unavailable.

Crate Classification and Targets

flowchart TD
subgraph target_environments["Target Environments"]
    edition_2024["Rust Edition 2024"]
    triple_license["Triple License Compatibility"]
    min_rust["Minimum Rust 1.85"]
    no_std["no_std Environment"]
    embedded["Embedded Systems"]
    kernel["Kernel Development"]
    arceos_os["ArceOS Operating System"]
    metadata["Crate Metadata"]
end
subgraph flatten_objects_crate["flatten_objects Crate"]
    arceos_os["ArceOS Operating System"]
    categories["categories: [no-std, data-structures]"]
    keywords["keywords: [arceos, data-structures]"]
    rust_version["rust-version: 1.85"]
    subgraph compatibility_matrix["Compatibility Matrix"]
        edition_2024["Rust Edition 2024"]
        triple_license["Triple License Compatibility"]
        min_rust["Minimum Rust 1.85"]
        no_std["no_std Environment"]
        embedded["Embedded Systems"]
        kernel["Kernel Development"]
        metadata["Crate Metadata"]
    end
end

metadata --> categories
metadata --> keywords
metadata --> rust_version

Sources: Cargo.toml(L1 - L13) 

Dependencies Analysis

The crate maintains a minimal dependency footprint with only one external dependency to ensure compatibility with resource-constrained environments.

External Dependencies

The bitmaps crate version 3.2 serves as the sole external dependency, providing efficient bitmap operations for ID management:

[dependencies]
bitmaps = { version = "3.2", default-features = false }

The default-features = false configuration ensures no_std compatibility by disabling standard library features of the bitmaps crate.

Dependency Relationship Diagram

flowchart TD
subgraph internal_usage["Internal Usage in flatten_objects"]
    id_bitmap["id_bitmap: Bitmap"]
    id_management["ID Management System"]
    allocation_tracking["Allocation Tracking"]
end
subgraph bitmaps_features["bitmaps Crate Features"]
    default_features_disabled["default-features = false"]
    no_std_compat["no_std compatibility"]
    bitmap_ops["Bitmap Operations"]
end
subgraph flatten_objects_dependencies["flatten_objects Dependencies"]
    flatten_objects["flatten_objects"]
    bitmaps_dep["bitmaps v3.2"]
    core_std["core (no_std)"]
end

bitmap_ops --> id_bitmap
bitmaps_dep --> bitmap_ops
bitmaps_dep --> default_features_disabled
default_features_disabled --> no_std_compat
flatten_objects --> bitmaps_dep
flatten_objects --> core_std
id_bitmap --> id_management
id_management --> allocation_tracking

Dependency Rationale

The bitmaps crate integration enables the FlattenObjects container to efficiently track which IDs are allocated using bitwise operations, essential for the ID reuse mechanism.

Sources: Cargo.toml(L15 - L16) 

ArceOS Ecosystem Integration

The flatten_objects crate is designed specifically for integration within the ArceOS operating system ecosystem, serving as a foundational data structure for kernel-level resource management.

Ecosystem Positioning

The crate's homepage points to the broader ArceOS project (https://github.com/arceos-org/arceos), indicating its role as a component within a larger operating system framework.

ArceOS Integration Architecture

flowchart TD
subgraph kernel_integration_points["Kernel Integration Points"]
    process_descriptors["Process Descriptors"]
    file_handles["File Handles"]
    memory_regions["Memory Regions"]
    device_handles["Device Handles"]
end
subgraph flatten_objects_role["flatten_objects Role"]
    flatten_objects_lib["flatten_objects Library"]
    object_pools["Object Pools"]
    handle_tables["Handle Tables"]
    resource_mgmt["Resource Management"]
    id_allocation["ID Allocation"]
end
subgraph arceos_ecosystem["ArceOS Ecosystem"]
    arceos_kernel["ArceOS Kernel"]
    process_mgmt["Process Management"]
    memory_mgmt["Memory Management"]
    file_system["File System"]
    device_drivers["Device Drivers"]
end

arceos_kernel --> flatten_objects_lib
device_drivers --> id_allocation
file_system --> resource_mgmt
flatten_objects_lib --> handle_tables
flatten_objects_lib --> id_allocation
flatten_objects_lib --> object_pools
flatten_objects_lib --> resource_mgmt
handle_tables --> file_handles
id_allocation --> device_handles
memory_mgmt --> handle_tables
object_pools --> process_descriptors
process_mgmt --> object_pools
resource_mgmt --> memory_regions

Target Use Cases

The crate addresses specific requirements in kernel and embedded development:

• Fixed-capacity containers: Essential for predictable memory usage in kernel environments
• Efficient ID reuse: Critical for long-running systems that create and destroy many objects
• No heap allocation: Required for kernel code and embedded systems with limited memory
• Type-safe object storage: Maintains memory safety while allowing low-level optimizations

Sources: Cargo.toml(L8 - L11) 

Project Structure Overview

Based on the crate configuration and typical Rust library conventions, the project follows a standard structure optimized for library distribution and ArceOS integration.

Repository Structure

Project Organization Diagram

flowchart TD
subgraph repository_root["Repository Root"]
    ci_workflow["CI/CD Pipeline"]
    package_metadata["Package Metadata"]
    public_api["Public API Methods"]
    cargo_toml["Cargo.toml"]
    readme_md["README.md"]
    gitignore[".gitignore"]
    src_dir["src/"]
end
subgraph configuration_files["Configuration Files"]
    flatten_objects_struct["FlattenObjects"]
    subgraph development_infrastructure["Development Infrastructure"]
        ci_workflow["CI/CD Pipeline"]
        documentation["API Documentation"]
        multi_target["Multi-target Support"]
        package_metadata["Package Metadata"]
        dependency_spec["Dependency Specification"]
        build_config["Build Configuration"]
        lib_rs["src/lib.rs"]
    end
end
subgraph source_structure["Source Structure"]
    ci_workflow["CI/CD Pipeline"]
    documentation["API Documentation"]
    package_metadata["Package Metadata"]
    dependency_spec["Dependency Specification"]
    lib_rs["src/lib.rs"]
    flatten_objects_struct["FlattenObjects"]
    public_api["Public API Methods"]
    internal_impl["Internal Implementation"]
    cargo_toml["Cargo.toml"]
    readme_md["README.md"]
end

flatten_objects_struct --> internal_impl
flatten_objects_struct --> public_api
lib_rs --> flatten_objects_struct

Build and Distribution Configuration

The crate is configured for distribution through the standard Rust package ecosystem while maintaining specialized requirements for kernel development:

The minimal dependency configuration ensures fast compilation and reduces the attack surface for security-critical kernel components.

Sources: Cargo.toml(L1 - L17)