Struct dbs_utils::epoll_manager::EpollManager

pub struct EpollManager {
    pub mgr: Arc<Mutex<EventManager<EpollSubscriber>>>,
    /* private fields */
}

A wrapper struct over EventManager to solve possible deadlock.

It’s a rather tough topic to deal with the epoll event manager in rust way. The event_manager::EventManager is designed for single-threaded environment and it leaves the task for concurrent access to the clients. There are two types of threads involved, epoll worker thread and vCPU threads. To reduce overhead, the epoll worker thread calls epoll::wait() without timeout, so the worker thread will hold the EpollManagerImpl::Mutex for undetermined periods. When the vCPU threads tries to activate virtio devices, they need to acquire the same EpollManagerImpl::Mutex. Thus the vCPU threads may block for an undetermined time. To solve this issue, we perform an kick()/try_lock() loop to wake up the epoll worker thread from sleeping.

Fields

mgr: Arc<Mutex<EventManager<EpollSubscriber>>>

Implementations

impl EpollManager

pub fn add_subscriber(&self, handler: EpollSubscriber) -> SubscriberId

Add a new epoll event subscriber.

pub fn remove_subscriber(
    &mut self,
    subscriber_id: SubscriberId
) -> Result<EpollSubscriber>

Remove a given epoll event subscriber.

pub fn add_event(
    &self,
    subscriber_id: SubscriberId,
    events: Events
) -> Result<(), Error>

Add an epoll event to be monitored.

pub fn handle_events(&self, timeout: i32) -> Result<usize, Error>

Run the epoll polling loop.

Trait Implementations

impl Clone for EpollManager

fn clone(&self) -> EpollManager

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Default for EpollManager

fn default() -> Self

Create a new epoll manager.