Struct Device 

pub struct Device { /* private fields */ }

Device representation for tensor operations

A device specifies where tensors are located and where operations should be performed. Each device has a type (CPU or CUDA) and an index (0 for CPU, GPU ID for CUDA). The device system provides thread-safe context management and automatic resource cleanup.

Fields

• device_type - The type of device (CPU or CUDA)
• index - Device index (0 for CPU, GPU ID for CUDA)

Examples

use train_station::Device;

// Create CPU device
let cpu = Device::cpu();
assert!(cpu.is_cpu());
assert_eq!(cpu.index(), 0);
assert_eq!(cpu.to_string(), "cpu");

// Create CUDA device (when feature enabled)
#[cfg(feature = "cuda")]
{
    if train_station::cuda_is_available() {
        let cuda = Device::cuda(0);
        assert!(cuda.is_cuda());
        assert_eq!(cuda.index(), 0);
        assert_eq!(cuda.to_string(), "cuda:0");
    }
}

Thread Safety

This type is thread-safe and can be shared between threads. Device contexts are managed per-thread using thread-local storage.

Memory Layout

The device struct is small and efficient:

• Size: 16 bytes (8 bytes for enum + 8 bytes for index)
• Alignment: 8 bytes
• Copy semantics: Implements Copy for efficient passing

Implementations

impl Device

pub fn cpu() -> Self

Create a CPU device

CPU devices always have index 0 and are always available regardless of feature flags or system configuration.

Returns

A Device representing the CPU (always index 0)

Examples

use train_station::Device;

let device = Device::cpu();
assert!(device.is_cpu());
assert_eq!(device.index(), 0);
assert_eq!(device.device_type(), train_station::DeviceType::Cpu);

Examples found in repository

examples/getting_started/tensor_basics.rs (line 201)

fn demonstrate_utility_functions() {
    println!("\n--- Utility Functions ---");

    let tensor = Tensor::from_slice(&[1.0, 2.0, 3.0, 4.0], vec![2, 2]).unwrap();

    // Basic properties
    println!("Shape: {:?}", tensor.shape().dims);
    println!("Size: {}", tensor.size());
    println!("Is contiguous: {}", tensor.is_contiguous());
    println!("Device: {:?}", tensor.device());

    // Mathematical operations
    let sum = tensor.sum();
    println!("Sum: {}", sum.value());

    let mean = tensor.mean();
    println!("Mean: {}", mean.value());

    let norm = tensor.norm();
    println!("Norm: {}", norm.value());

    // Device placement
    let cpu_tensor = Tensor::zeros_on_device(vec![3, 3], train_station::Device::cpu());
    println!(
        "CPU tensor: shape {:?}, device: {:?}",
        cpu_tensor.shape().dims,
        cpu_tensor.device()
    );
}

pub fn cuda(index: usize) -> Self

Create a CUDA device

Creates a device representing a specific CUDA GPU. The device index must be valid for the current system configuration.

Arguments

• index - CUDA device index (0-based)

Returns

A Device representing the specified CUDA device

Panics

Panics in the following cases:

• CUDA feature is not enabled (--features cuda not specified)
• CUDA is not available on the system
• Device index is out of range (>= number of available devices)

Examples

use train_station::Device;

// CPU device is always available
let cpu = Device::cpu();

// CUDA device (when feature enabled and available)
#[cfg(feature = "cuda")]
{
    if train_station::cuda_is_available() {
        let device_count = train_station::cuda_device_count();
        if device_count > 0 {
            let cuda = Device::cuda(0);
            assert!(cuda.is_cuda());
            assert_eq!(cuda.index(), 0);
        }
    }
}

pub fn device_type(&self) -> DeviceType

Get the device type

Returns

The DeviceType enum variant representing this device’s type

Examples

use train_station::{Device, DeviceType};

let cpu = Device::cpu();
assert_eq!(cpu.device_type(), DeviceType::Cpu);

pub fn index(&self) -> usize

Get the device index

Returns

The device index (0 for CPU, GPU ID for CUDA)

Examples

use train_station::Device;

let cpu = Device::cpu();
assert_eq!(cpu.index(), 0);

#[cfg(feature = "cuda")]
{
    if train_station::cuda_is_available() {
        let cuda = Device::cuda(0);
        assert_eq!(cuda.index(), 0);
    }
}

pub fn is_cpu(&self) -> bool

Check if this is a CPU device

Returns

true if this device represents a CPU, false otherwise

Examples

use train_station::Device;

let cpu = Device::cpu();
assert!(cpu.is_cpu());
assert!(!cpu.is_cuda());

pub fn is_cuda(&self) -> bool

Check if this is a CUDA device

Returns

true if this device represents a CUDA GPU, false otherwise

Examples

use train_station::Device;

let cpu = Device::cpu();
assert!(!cpu.is_cuda());
assert!(cpu.is_cpu());

Trait Implementations

impl Clone for Device

fn clone(&self) -> Device

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Device

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Device

fn default() -> Self

Create the default device (CPU)

Returns

A CPU device (same as Device::cpu())

Examples

use train_station::Device;

let device = Device::default();
assert!(device.is_cpu());
assert_eq!(device, Device::cpu());

impl Display for Device

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Format the device as a string

Returns

String representation of the device:

• "cpu" for CPU devices
• "cuda:{index}" for CUDA devices

Examples

use train_station::Device;

let cpu = Device::cpu();
assert_eq!(cpu.to_string(), "cpu");

#[cfg(feature = "cuda")]
{
    if train_station::cuda_is_available() {
        let cuda = Device::cuda(0);
        assert_eq!(cuda.to_string(), "cuda:0");
    }
}

impl From<DeviceType> for Device

fn from(device_type: DeviceType) -> Self

Convert DeviceType to Device with index 0

Arguments

• device_type - The device type to convert

Returns

A Device with the specified type and index 0

Panics

Panics if device_type is DeviceType::Cuda and CUDA is not available or the feature is not enabled.

Examples

use train_station::{Device, DeviceType};

let cpu_type = DeviceType::Cpu;
let cpu_device = Device::from(cpu_type);
assert!(cpu_device.is_cpu());
assert_eq!(cpu_device.index(), 0);

impl FromFieldValue for Device

fn from_field_value( value: FieldValue, field_name: &str, ) -> SerializationResult<Self>

Convert FieldValue to Device for deserialization

Arguments

• value - FieldValue containing device object
• field_name - Name of the field for error reporting

Returns

Device instance or error if invalid

impl Hash for Device

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Device

fn eq(&self, other: &Device) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl ToFieldValue for Device

fn to_field_value(&self) -> FieldValue

Convert Device to FieldValue for serialization

Returns

Object containing device type and index

impl Copy for Device

impl Eq for Device

impl StructuralPartialEq for Device