Health Checks

This issue is meant to track the various classes and state that we hope to integrate with the health check framework. The following like appears in no order of importance.

BookKeeperLog - ✔️

• private final WriteQueue writes : Capture the number of writes and the length of the queue.

DurableLog - ✔️

• isOffline(): Capture if the durable log is considered offline or not.
• state(): Report the State of the service (extends AbstractService).

InMemoryLog - ✔️

• size(): Captures the size of the queue (extends AbstractDrainingQueue).

OperationProcessor - ✔️

• state(): Report the State of the service (extends AbstractService).
• private final PriorityBlockingDrainingQueue<CompletableOperation> operationQueue;: Report the size() of this queue.
• private final BlockingDrainingQueue<List<CompletableOperation>> commitQueue;: Report the size() of this queue.

StreamSegmentContainer - ✔️

• private final OperationLog durableLog: Report the State (state()) of the service (extends AbstractService).
• private final Writer writer: Report the State (state()) of the service (extends AbstractService).
• private final MetadataCleaner metadataCleaner: Report the State (state()) of the service (extends AbstractService).

StreamSegmentContainerMetadata - ✔️

• getActiveSegmentCount(): Reports the amount of active segments.
• getOperationSequenceNumber(): Reports the current operation sequence number.
• Report the difference between sequenceNumber and the lastTruncatedSequenceNumber.

_{Let these symbols, ✔️ and ❌, represent a complete and not-started state respectively.}