Implementation:Apache Shardingsphere MetaDataContexts Container

Knowledge Sources	Apache_Shardingsphere
Domains	Mode_Management, Metadata
Last Updated	2026-02-10 00:00 GMT

Overview

Thread-safe container holding the runtime metadata and statistics contexts for a ShardingSphere instance.

Description

MetaDataContexts wraps ShardingSphereMetaData and ShardingSphereStatistics in AtomicReference objects for thread-safe access. It provides atomic update methods for both metadata and statistics, used throughout the ShardingSphere runtime when configurations change or metadata is refreshed.

Usage

This is the central runtime state object accessed by all components. It is created during context initialization and updated atomically when rule configurations, schemas, or statistics change.

Code Reference

Source Location

• Repository: Apache_Shardingsphere
• File: MetaDataContexts.java
• Lines: 1-81

Signature

public final class MetaDataContexts {

    private final AtomicReference<ShardingSphereMetaData> metaData;
    private final AtomicReference<ShardingSphereStatistics> statistics;

    public MetaDataContexts(ShardingSphereMetaData metaData, ShardingSphereStatistics statistics);

    public ShardingSphereMetaData getMetaData();
    public ShardingSphereStatistics getStatistics();
    public void update(ShardingSphereMetaData metaData);
    public void update(ShardingSphereStatistics statistics);
}

Import

import org.apache.shardingsphere.mode.metadata.MetaDataContexts;

I/O Contract

Inputs

Name	Type	Required	Description
metaData	ShardingSphereMetaData	Yes	Runtime metadata (databases, rules, props)
statistics	ShardingSphereStatistics	Yes	Runtime statistics data

Outputs

Name	Type	Description
getMetaData()	ShardingSphereMetaData	Current metadata reference
getStatistics()	ShardingSphereStatistics	Current statistics reference

Usage Examples

import org.apache.shardingsphere.mode.metadata.MetaDataContexts;

// Created during initialization
MetaDataContexts contexts = new MetaDataContexts(metaData, statistics);

// Thread-safe read
ShardingSphereMetaData currentMeta = contexts.getMetaData();

// Atomic update after rule change
contexts.update(newMetaData);

Related Pages

• Principle:Apache_Shardingsphere_MetaData_Context_Creation