Replace the heartbeat lock in AppHang Plugin

[lemnik]

Goal

Remove the heartbeat lock in the AppHang plugin to avoid possibly locking the main thread when the monitor holds the lock at the same time.

Design

Replaced the lock & condition signalling with the park/unpark primitives. These only allow a single "block" / "unblock" behaviour, but the "parked" thread suits our use-case significantly better. This should reduce the overhead on the main thread.

Changes

• Replaced the lock & condition with park/unpark
• Replaced the elapsedRealtime clock with uptimeMillis which doesn't tick during deep sleeps, avoiding deep sleep triggering false-positive AppHangs
• Moved the heartbeat re-posting to the monitor thread so that the heartbeat, improving the throughput on the main thread

sequenceDiagram
    activate monitor
    monitor->>main: heartbeat
    deactivate monitor
    activate main
    main->>monitor: unpark
    deactivate main
    activate monitor
    monitor->>main: heartbeat
    deactivate monitor
    activate main
    main->>monitor: unpark
    deactivate main
    activate monitor

Loading

Testing

Relied on existing tests.

[bugsnagbot]

Android notifier sizes

Format	Size impact of Bugsnag (kB)	Size impact of Bugsnag when Minified (kB)
APK	1842.46	1603.54
arm64_v8a	651.52	409.86
armeabi_v7a	594.18	352.52
x86	725.23	483.57
x86_64	696.57	454.9

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[YYChen01988]

LGTM