Implementation:Datahub project Datahub WriteTrackingAspectCache

Knowledge Sources	Datahub_project_Datahub
Domains	Java_SDK, Metadata_Management
Last Updated	2026-02-10 00:00 GMT

Overview

Description

WriteTrackingAspectCache is an extended, thread-safe cache for entity aspects with TTL-based expiration and dirty tracking. It extends the caching concept of AspectCache by adding support for distinguishing between server-sourced and locally-sourced aspects, tracking dirty (unsaved) state, and controlling read visibility via ReadMode.

Note: This class is currently not in active use. It is preserved for future implementation of write tracking and read-your-own-writes semantics.

Key capabilities:

• TTL-based expiration for SERVER-sourced aspects; LOCAL-sourced aspects never expire
• Dirty tracking to identify aspects with pending writes
• Read modes: ALLOW_DIRTY returns dirty aspects (read-your-own-writes), SERVER_ONLY filters them out
• Thread-safe operations via ConcurrentHashMap

Usage

This cache would be used by entity objects to track both fetched and locally modified aspects. Callers use put() with an AspectSource and dirty flag, get() with a ReadMode, and markDirty() / markClean() to manage write state. After a successful server save, clearDirty() resets all dirty flags.

Code Reference

Source Location

metadata-integration/java/datahub-client/src/main/java/datahub/client/v2/entity/WriteTrackingAspectCache.java

Signature

public class WriteTrackingAspectCache {

    public WriteTrackingAspectCache(long ttlMillis)

    @Nullable
    public <T extends RecordTemplate> T get(
        @Nonnull String aspectName,
        @Nonnull Class<T> aspectClass,
        @Nonnull ReadMode readMode)

    public void put(
        @Nonnull String aspectName,
        @Nonnull RecordTemplate aspect,
        @Nonnull AspectSource source,
        boolean dirty)

    public void markDirty(@Nonnull String aspectName)

    @Nonnull
    public Map<String, RecordTemplate> getDirtyAspects()

    public boolean hasPendingWrites(@Nonnull String aspectName)

    public void markClean(@Nonnull String aspectName)

    public void clearDirty()

    @Nullable
    public RecordTemplate remove(@Nonnull String aspectName)

    @Nonnull
    public Map<String, RecordTemplate> getAllAspects()

    public boolean isEmpty()

    public int size()
}

Import

import datahub.client.v2.entity.WriteTrackingAspectCache;

I/O Contract

Inputs

Method	Parameter	Type	Description
constructor	ttlMillis	long	TTL in milliseconds for SERVER-sourced aspects
get	aspectName	String	Name of the aspect to retrieve
get	aspectClass	Class<T>	Expected class of the aspect
get	readMode	ReadMode	ALLOW_DIRTY or SERVER_ONLY
put	aspectName	String	Name of the aspect to store
put	aspect	RecordTemplate	The aspect data to cache
put	source	AspectSource	SERVER or LOCAL
put	dirty	boolean	Whether the aspect has unsaved modifications
markDirty	aspectName	String	Name of the aspect to mark dirty
markClean	aspectName	String	Name of the aspect to mark clean
remove	aspectName	String	Name of the aspect to remove

Outputs

Method	Return Type	Description
get	T (nullable)	Cached aspect or null if not found, expired, or filtered by read mode
getDirtyAspects	Map<String, RecordTemplate>	All aspects with unsaved modifications
hasPendingWrites	boolean	Whether the named aspect has pending writes
remove	RecordTemplate (nullable)	The removed aspect data or null
getAllAspects	Map<String, RecordTemplate>	All cached aspects (clean and dirty)
isEmpty	boolean	Whether the cache is empty
size	int	Number of cached aspects

Usage Examples

// Create a cache with 60-second TTL for server-sourced aspects
WriteTrackingAspectCache cache = new WriteTrackingAspectCache(60_000L);

// Store a server-sourced aspect (subject to TTL)
cache.put("ownership", ownershipAspect, AspectSource.SERVER, false);

// Store a locally modified aspect (never expires, starts dirty)
cache.put("description", descAspect, AspectSource.LOCAL, true);

// Read with different modes
Ownership ownership = cache.get("ownership", Ownership.class, ReadMode.ALLOW_DIRTY);
Ownership serverOnly = cache.get("ownership", Ownership.class, ReadMode.SERVER_ONLY);

// Check and manage dirty state
boolean pending = cache.hasPendingWrites("description");
cache.markClean("description");
cache.clearDirty();

// Get all dirty aspects for batch save
Map<String, RecordTemplate> dirtyAspects = cache.getDirtyAspects();

Related Pages

• Datahub_project_Datahub_AspectCache - Simple TTL-based cache (currently in active use)
• Datahub_project_Datahub_AspectWithMetadata - Wrapper for aspects with version metadata
• Datahub_project_Datahub_PendingMutationsException - Exception for reads on entities with pending mutations