Crate relay_system

Foundational system components for Relay’s services.

Relay’s system is based on [tokio]. To use any of these components, ensure a tokio runtime is available.

Services

The basic building block in Relay are asynchronous Services. Each service implements an Interface, which consists of one or many messages that can be sent to the service using its Addr. See the docs of these types for more information on how to implement and use them.

Shutdown

The static Controller service can listen for process signals and initiate a graceful shutdown. Note that services must check a ShutdownHandle to receive these signals. See the struct level documentation for more information.

Macros

• spawn
  Spawns an instrumented task with an automatically generated TaskId.

Structs

• Addr
  The address of a Service.
• AsyncResponse
  Message response resulting in an asynchronous Request.
• BroadcastChannel
  A channel that broadcasts values to attached senders.
• BroadcastRequest
  The request when sending an asynchronous message to a service.
• BroadcastResponse
  Variation of AsyncResponse that efficiently broadcasts responses to many requests.
• BroadcastSender
  Sends a message response from a service back to the waiting BroadcastRequest.
• Builder
  Configures a Relay Runtime.
• Controller
  Service to start and gracefully stop the system runtime.
• NoResponse
  Message response for fire-and-forget messages with no output.
• Receiver
  Inbound channel for messages sent through an Addr.
• Recipient
  An address to a Service implementing any interface that takes a given message.
• Request
  The request when sending an asynchronous message to a service.
• Runtime
  A Relay async runtime.
• RuntimeMetrics
  Handle to the Runtime’s metrics.
• SendError
  An error when sending a message to a service fails.
• Sender
  Sends a message response from a service back to the waiting Request.
• ServiceRunner
  Keeps track of running services.
• Shutdown
  Shutdown request message sent by the Controller to subscribed services.
• ShutdownHandle
  Notifies a service about an upcoming shutdown.
• TaskId
  An identifier for tasks spawned by spawn(), used to log metrics.

Enums

• ShutdownMode
  Determines how to shut down the Relay system.

Traits

• FromMessage
  Declares a message as part of an Interface.
• Interface
  A message interface for services.
• MessageResponse
  Response behavior of an Interface message.
• Service
  An asynchronous unit responding to messages.

Functions

• channel
  Creates an unbounded channel for communicating with a Service.
• spawn
  Spawns a new asynchronous task, returning a [JoinHandle] for it.