engineering: Add gRPC server base

[frhuelsz]

🔍 Description

Completes #397.

This PR adds the base infrastructure and behavior of the gRPC server.

Depends on

• engineering: Remove original gRPC impl #410
• engineering: Harpoon gRPC Protobuf #386
• engineering: Introduce gRPC logging facilities #411

An attempt to make a mostly accurate arch diagram from all this. I will add a doc with this in the future.

flowchart TD

subgraph harpoon [Harpoon Crate]
  service[TridentService]
end

subgraph Trident
  real_main[main]
  logfwd["Log Forwarder"]
  real_main-->|creates|logfwd
  subgraph Server Module
    main[server_main]
    listener[Unix Socket Listener]
    tracker[Activity Tracker]
    timer[Shutdown Timer]
    tracker-->|starts/cancels|timer
    timer-->|stops|tonic
    middleware[Tracker Middleware]
    subgraph grpc ["gRPC Server (tonic)"]
      tonic["Tonic gRPC Server"]
      middleware[Tracker Middleware]
      tonic-->|uses|middleware
      subgraph server[Harpoon Server]
        rpcs["RPC Methods"]
        rpcs-->|create| resp[Response<br/>Stream Channel]
        rpcs-->|spawn|logtask["Log Fwing Task"]
        logtask-->|sends logs|resp
        connLock[Connection RWLock]
        subgraph mgr[Servicing Manager]
          srvLock[Servicing RW Lock]
          srvCaller[Servicing Callers]
          srvCaller<-->|try lock|srvLock
          srvBlock["Servicing Task (Blocking)"]
          srvCaller<-->|start|srvBlock
        end
        rpcs<-->|try lock|connLock
        rpcs-->|invoke|srvCaller
        srvCaller-->|sends result|resp
      end
      tonic-->|invokes|rpcs
    end
    listener-->|used by|tonic
    service-->|implemented by|server
    main-->|creates| listener
    main-->|creates| tracker
    tracker-->|creates| middleware
    middleware-->|notify conn<br/>start/end| tracker
    main-->|starts| grpc
    srvCaller-->|notifies servicing<br/>start/end|tracker
  end
  logfwd-->|sends to|logtask
  real_main-->|invokes|main
  subgraph TridentCore
    servicing["Servicing action"]
  end

  srvBlock<-->|"runs (NOT IMPL YET)"|servicing
end

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[Copilot]

Pull request overview

This PR adds foundational gRPC server infrastructure to support servicing operations in Trident, including activity tracking, connection management, log forwarding, and systemd socket activation support.

Key changes:

• Implements TridentHarpoonServer with servicing request handling and lock-based concurrency control
• Adds ActivityTracker to monitor connections and servicing operations with automatic shutdown on inactivity
• Introduces systemd socket activation support with Unix domain socket handling

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
crates/trident/src/server/tridentserver/servicingmgr.rs	Manages servicing locks and spawns blocking servicing tasks with activity tracking
crates/trident/src/server/tridentserver/mod.rs	Implements gRPC TridentService with stub methods, request handlers, and log forwarding
crates/trident/src/server/support/stream.rs	Provides StreamWithLock wrapper for managing gRPC streams with associated lock guards
crates/trident/src/server/support/fds.rs	Handles systemd socket activation and Unix socket file descriptor management
crates/trident/src/server/mod.rs	Main server entry point with listener setup and signal handling
crates/trident/src/server/activitytracker/tracker.rs	Tracks active connections and servicing with configurable inactivity timeout
crates/trident/src/server/activitytracker/timer.rs	Simple timer implementation with cancellation support for inactivity tracking
crates/trident/src/server/activitytracker/middleware.rs	Tonic middleware for automatic connection tracking via request/response lifecycle
crates/trident/src/lib.rs	Conditionally includes server module for testing
crates/trident/Cargo.toml	Adds gRPC dependencies (tonic, hyper, tokio-stream) and updates nix to 0.30.1

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Pull request overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated 3 comments.

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Pull request overview

Copilot reviewed 18 out of 19 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 18 out of 19 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 18 out of 19 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 18 out of 19 changed files in this pull request and generated 2 comments.

[ayaegashi]

a couple nits, but otherwise LGTM