Class ConfigMigrator

java.lang.Object

com.loomcache.server.config.ConfigMigrator

public final class ConfigMigrator
extends Object

Migrates configuration across schema versions.

When loading a configuration file, detects its schema version and applies migration functions to transform it to the current schema version.

Supports: - Auto-detection of schema version from config (schemaVersion field, default 1) - Registration of migration functions for version transitions - Graceful handling of missing or invalid schema versions

Example usage:

Mapinvalid input: '<'String, Object> raw = loadFromFile(...);
Mapinvalid input: '<'String, Object> migrated = ConfigMigrator.migrate(raw);
LoomConfig config = buildFromMap(migrated);

Thread-safe: The migrate() method can be called from multiple threads.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ConfigMigrator.ConfigMigrationException	Exception thrown when configuration migration fails.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	CONFIG_SCHEMA_VERSION

Constructor Summary

Constructors

Constructor	Description
ConfigMigrator()

Method Summary

Modifier and Type	Method	Description
static void	clearMigrations()	Clear all registered migrations (for testing).
static Map<String,Object>	migrate(@Nullable Map<String,Object> raw)	Migrate a raw configuration map to the current schema version.
static Map<String,Object>	migrate(Map<String,Object> raw, int fromVersion, int toVersion)	Migrate configuration from source version to target version.
static void	registerMigration(int fromVersion, BiFunction<Map<String,Object>, Integer, Map<String,Object>> migrator)	Register a migration function for a version transition.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

CONFIG_SCHEMA_VERSION

public static final int CONFIG_SCHEMA_VERSION

See Also:

• Constant Field Values

Constructor Details

ConfigMigrator

public ConfigMigrator()

Method Details

migrate

public static Map<String,Object> migrate(@Nullable Map<String,Object> raw)

Migrate a raw configuration map to the current schema version.

Auto-detects the source schema version (defaults to 1 if not found). Applies migration functions sequentially from source version to current version.

Parameters:

raw - Raw configuration map from file (may be null)

Returns:

Migrated configuration map (or the input if no migration needed)

migrate

public static Map<String,Object> migrate(Map<String,Object> raw,
 int fromVersion,
 int toVersion)

Migrate configuration from source version to target version.

Applies migration functions sequentially for each version step.

Parameters:

raw - Raw configuration

fromVersion - Source schema version

toVersion - Target schema version

Returns:

Migrated configuration

registerMigration

public static void registerMigration(int fromVersion,
 BiFunction<Map<String,Object>, Integer, Map<String,Object>> migrator)

Register a migration function for a version transition. Used by test code to register custom migrations.

clearMigrations

public static void clearMigrations()

Clear all registered migrations (for testing).