Struct Context 

pub struct Context { /* private fields */ }

A handle to an open RDMA device context.

The Context represents an active user-space session with a specific RDMA device. It serves as the root factory for creating all other RDMA resources.

Resource Management & Shared Ownership

The Context uses shared ownership (via Arc) to manage the underlying device connection. This design simplifies resource management by allowing multiple handles to the same hardware context.

All resources created from a Context (such as ProtectionDomain, CompletionQueue, etc.) implicitly hold a clone of this Arc. This creates a robust ownership hierarchy:

1. Child Keeps Parent Alive: Even if you drop your main Context handle, the underlying hardware connection remains open as long as any child resource (PD, QP, MR) is still alive.
2. Automatic Cleanup: The actual ibv_close_device call only happens when the last reference to the context is dropped.

Example: The Resource Lifecycle

use ibverbs_rs::ibverbs;

let context = ibverbs::open_device("mlx5_0")?;

// Create resources — they hold a reference to the context internally.
let pd = context.allocate_pd()?;
let cq = context.create_cq(16)?;

// Drop the context explicitly (optional).
// The device connection remains OPEN because 'pd' and 'cq' are still alive.
drop(context);

// End of scope: 'pd' and 'cq' are dropped, ref count hits zero, context closes.

Implementations

impl Context

pub fn create_cq(&self, min_cq_entries: u32) -> IbvResult<CompletionQueue>

Creates a Completion Queue (CQ) on this device.

The CQ is used to receive completion notifications for work requests posted to Queue Pairs. The returned CompletionQueue will hold a clone of this Context, keeping the device connection alive.

Arguments

• min_cq_entries — The minimum number of entries the CQ must support. The hardware may allocate a larger queue.

Errors

• Returns IbvError::InvalidInput if min_cq_entries exceeds the device’s capabilities.
• Returns IbvError::Resource if the system cannot allocate the queue resources (e.g., out of memory).

pub fn allocate_pd(&self) -> IbvResult<ProtectionDomain>

Allocates a Protection Domain (PD) for this context.

A PD is a container for grouping Queue Pairs and Memory Regions. The returned ProtectionDomain will hold a strong reference to this Context, ensuring the underlying device connection remains open even if the original Context handle is dropped.

Errors

• Returns IbvError::Resource if the PD limit for the device has been reached or if memory allocation fails.

impl Context

pub fn from_device(dev: &Device<'_>) -> IbvResult<Self>

Opens a context for the given device and verifies port connectivity.

This function performs the following steps:

1. Calls ibv_open_device to establish a context.
2. Verifies the RDMA port is in ACTIVE or ARMED state.

Errors

• Returns IbvError::Permission if the process lacks permission to access RDMA devices.
• Returns IbvError::Driver if libibverbs fails to open the device for OS-specific reasons.
• Returns IbvError::Resource if the RDMA port is in any state other than ACTIVE or ARMED.

pub fn device(&self) -> Device<'_>

Returns a Device handle for the hardware backing this context.

Trait Implementations

impl Clone for Context

fn clone(&self) -> Context

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Context

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

Formats the value using the given formatter.