Package org.apache.cassandra.hints

Hints subsystem consists of several components.

See: Description

Interface Summary

Interface	Description
HintsServiceMBean
InputPosition	Marker interface for file positions as provided by the various ChecksummedDataReader implementations.

Class Summary

Class	Description
ChecksummedDataInput	A RandomAccessReader wrapper that calculates the CRC in place.
CompressedChecksummedDataInput
CompressedHintsWriter
EncryptedChecksummedDataInput
EncryptedHintsWriter
Hint	Encapsulates the hinted mutation, its creation time, and the gc grace seconds param for each table involved.
HintMessage	The message we use to dispatch and forward hints.
HintMessage.Serializer
HintResponse	An empty successful response to a HintMessage.
HintsService	A singleton-ish wrapper over various hints components: - a catalog of all hints stores - a single-threaded write executor - a multi-threaded dispatch executor - the buffer pool for writing hints into The front-end for everything hints related.
HintVerbHandler	Verb handler used both for hint dispatch and streaming.
LegacyHintsMigrator	A migrator that goes through the legacy system.hints table and writes all the hints to the new hints storage format.

Package org.apache.cassandra.hints Description

Hints subsystem consists of several components. Hint encodes all the required metadata and the mutation being hinted. HintsBuffer provides a temporary buffer for writing the hints to in a concurrent manner, before we flush them to disk. HintsBufferPool is responsible for submitting HintsBuffer instances for flushing when they exceed their capacity, and for maitaining a reserve HintsBuffer instance, and creating extra ones if flushing cannot keep up with arrival rate. HintsWriteExecutor is a single-threaded executor that performs all the writing to disk. HintsDispatchExecutor is a multi-threaded executor responsible for dispatch of the hints to their destinations. HintsStore tracks the state of all hints files (written and being written to) for a given host id destination. HintsCatalog maintains the mapping of host ids to HintsStore instances, and provides some aggregate APIs. HintsService wraps the catalog, the pool, and the two executors, acting as a front-end for hints.