Struct fidl_fuchsia_memorypressure::WatcherSynchronousProxy

pub struct WatcherSynchronousProxy { /* private fields */ }

Implementations

impl WatcherSynchronousProxy

pub fn new(channel: Channel) -> Self

pub fn into_channel(self) -> Channel

pub fn wait_for_event(&self, deadline: Time) -> Result<WatcherEvent, Error>

Waits until an event arrives and returns it. It is safe for other threads to make concurrent requests while waiting for an event.

pub fn on_level_changed( &self, level: Level, ___deadline: Time ) -> Result<(), Error>

Sent to the registered client when the memory pressure level changes. level: indicates the current memory pressure level.

Will also be invoked on initial connection via RegisterWatcher, so that a newly registered client can discover the current memory pressure level.

The watcher must immediately reply with a message to acknowledge that it has received the level change notification, and has initiated required actions as a result. It may then continue to reclaim memory asynchronously after sending the acknowledgement.

Some helpful guidelines for clients:

1. The watcher will be notified of new pressure level changes only after a reply corresponding to the previous message has been received by the provider. If multiple level transitions occur during that time, the watcher will be notified of the latest pressure level.

2. The level changes are edge-triggered, and clients are expected to maintain local state to track the current pressure level, if required. For example, a job might be notified of a CRITICAL level and drop all its caches as a result. Some time after this, it might want to trigger an activity that causes a fair amount of memory to be allocated. At this point, the job is expected to remember that the last pressure level it saw was CRITICAL, and refrain from triggering the memory-intensive activity.

3. As a performance optimization, the provider may decide to skip sending messages for some pressure level changes. For example, when oscillating across the NORMAL / WARNING boundary, it might not be worth notifying clients of every single transition. The provider might rate-limit messages in this case. On a similar note, the provider may decide to send repeated messages at the same pressure level, particularly CRITICAL, to indicate that further action needs to be taken.

Trait Implementations

impl Debug for WatcherSynchronousProxy

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

Formats the value using the given formatter.

impl SynchronousProxy for WatcherSynchronousProxy

type Proxy = WatcherProxy

The async proxy for the same protocol.

type Protocol = WatcherMarker

The protocol which this Proxy controls.

fn from_channel(inner: Channel) -> Self

Create a proxy over the given channel.

fn into_channel(self) -> Channel

Convert the proxy back into a channel.

fn as_channel(&self) -> &Channel

Get a reference to the proxy’s underlying channel.