Implementation:Datahub project Datahub AspectCache

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

Overview

Description

AspectCache is a simple TTL-based, thread-safe cache for entity aspects fetched from the DataHub server. It stores RecordTemplate aspect instances and automatically expires them after a configurable time-to-live (TTL) period. Expired aspects are lazily evicted on the next access attempt. The cache is backed by a ConcurrentHashMap for safe concurrent access from multiple threads.

This cache is the primary caching mechanism used by the Java SDK V2 entity layer to avoid redundant server fetches for recently accessed aspects.

Usage

AspectCache is used internally by entity objects to cache aspects retrieved from DataHub. Callers create an instance with a desired TTL in milliseconds, then use put() to store aspects and get() to retrieve them. Expired entries are transparently removed during retrieval.

Code Reference

Source Location

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

Signature

public class AspectCache {

    public AspectCache(long ttlMillis)

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

    public void put(@Nonnull String aspectName, @Nonnull RecordTemplate aspect)

    @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.AspectCache;

I/O Contract

Inputs

Method	Parameter	Type	Description
constructor	ttlMillis	long	Time-to-live in milliseconds for cached aspects
get	aspectName	String	The name of the aspect to retrieve
get	aspectClass	Class<T>	The expected class of the aspect
put	aspectName	String	The name of the aspect to store
put	aspect	RecordTemplate	The aspect data to cache
remove	aspectName	String	The name of the aspect to remove

Outputs

Method	Return Type	Description
get	T (nullable)	The cached aspect cast to the requested type, or null if not found or expired
put	void	Stores the aspect with current timestamp
remove	RecordTemplate (nullable)	The removed aspect data, or null if not present
getAllAspects	Map<String, RecordTemplate>	All cached aspects (including expired ones)
isEmpty	boolean	Whether the cache is empty
size	int	Number of cached aspects

Usage Examples

// Create a cache with a 60-second TTL
AspectCache cache = new AspectCache(60_000L);

// Store an aspect
cache.put("ownership", ownershipAspect);

// Retrieve an aspect (returns null if expired or absent)
Ownership ownership = cache.get("ownership", Ownership.class);

// Remove a specific aspect
cache.remove("ownership");

// Check cache state
boolean empty = cache.isEmpty();
int count = cache.size();

// Get all cached aspects (snapshot)
Map<String, RecordTemplate> all = cache.getAllAspects();

Related Pages

• Datahub_project_Datahub_WriteTrackingAspectCache - Extended cache with dirty tracking and read modes
• Datahub_project_Datahub_AspectWithMetadata - Wrapper for aspects with version metadata