Actuator & System Monitoring

Sketchboot seamlessly integrates with Spring Boot Actuator to provide deep visibility into the native Rust memory structures.

1. The /actuator/sketches Endpoint

Sketchboot registers a custom Actuator endpoint that allows you to inspect all currently active Count-Min Sketches in your JVM.

Prerequisites: Ensure you have exposed the endpoint in your application.yml:

management:
  endpoints:
    web:
      exposure:
        include: "health,metrics,sketches"

Fetching All Active Sketches

Request: GET /actuator/sketches

Response:

{
  "LIMIT_60000": "Active (1 MB)",
  "SHIELD_10000": "Active (1 MB)",
  "FRAUD_300000": "Active (1 MB)"
}

Note: Sketches are uniquely identified by their annotation type and time window (e.g., LIMIT_60000 means a @SketchLimit with a 60,000ms window).

Fetching Sketch Details

You can query a specific sketch for its mathematical properties.

Request: GET /actuator/sketches/LIMIT_60000

Response:

{
  "epsilon": 0.0000414,
  "memory_bytes": 1048576,
  "delta_percent": 1.8
}

This tells you that the sketch consumes exactly 1,048,576 bytes (1 MB) of off-heap memory, and has an over-count error bound of ~0.00004.

2. Dynamic Library Extraction Logging

When your application boots up, NativeLibraryLoader attempts to detect your Operating System (Linux, Windows, or Mac) and architecture. It extracts the appropriate binary (e.g., libcl_tds.so) from the .jar to your system’s temp directory and loads it.

If you ever encounter UnsatisfiedLinkError, check the startup logs for:

INFO: Sketchboot loading native library for OS: linux, Arch: amd64
INFO: Successfully extracted and loaded libcl_tds.so from /tmp/sketchboot_native_12345.so

If this fails, it is usually because the tmp folder lacks execution permissions or the JVM lacks --enable-native-access.