io.flamingock.internal.common.core.template

Class ChangeTemplateManager

java.lang.Object

io.flamingock.internal.common.core.template.ChangeTemplateManager

public final class ChangeTemplateManager
extends java.lang.Object

Runtime registry of ChangeTemplate implementations discovered through Java's ServiceLoader SPI.

The runtime entry point is loadTemplates() — called once during Flamingock initialization to populate the internal registry. After that, callers look templates up by name via getTemplate(String) or getTemplateOrFail(String).

This class is intentionally runtime-only. The GraalVM RegistrationFeature needs a build-time-safe way to enumerate templates without instantiating them (which would fire each template's <clinit> and pull SLF4J/Logback into the build-time image heap). That enumeration lives inside the flamingock-graalvm module so it can use the JDK 9+ ServiceLoader.Provider::type API; this module is Java-8 compatible and stays small.

Thread Safety Note: not thread-safe during initialization. loadTemplates() modifies static state and is intended to be called only once during application startup from a single thread. After initialization, the template registry is effectively read-only and can be safely accessed concurrently.

Method Summary

Modifier and Type	Method and Description
static void	addTemplate(java.lang.Class<? extends io.flamingock.api.template.ChangeTemplate<?,?,?>> templateClass) Adds a template to the internal registry for testing purposes.
static java.util.Optional<ChangeTemplateDefinition>	getTemplate(java.lang.String templateName) Retrieves a template definition by name from the internal registry.
static ChangeTemplateDefinition	getTemplateOrFail(java.lang.String templateName)
static void	loadTemplates() Loads and registers all available templates from the classpath into the internal registry.

Methods inherited from class java.lang.Object

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

Method Detail

loadTemplates

public static void loadTemplates()

Loads and registers all available templates from the classpath into the internal registry.

Runtime-only. Iterates ServiceLoader for ChangeTemplate, which instantiates each provider — that's fine here because we're at runtime; static initializers (loggers etc.) are allowed to fire. The build-time path that must not instantiate templates lives in the flamingock-graalvm module.

Not thread-safe; call once during application startup from a single thread, before any template lookups.

getTemplate

public static java.util.Optional<ChangeTemplateDefinition> getTemplate(java.lang.String templateName)

Retrieves a template definition by name from the internal registry.

This method is used during runtime to look up template definitions by their simple name. It returns an Optional that will be empty if no template with the specified name has been registered.

This method is thread-safe after initialization (after loadTemplates() has been called).

Parameters:

templateName - The simple class name of the template to retrieve

Returns:

An Optional containing the template definition if found, or empty if not found

getTemplateOrFail

public static ChangeTemplateDefinition getTemplateOrFail(java.lang.String templateName)

addTemplate

@TestOnly
public static void addTemplate(java.lang.Class<? extends io.flamingock.api.template.ChangeTemplate<?,?,?>> templateClass)

Adds a template to the internal registry for testing purposes.

This method is intended for use in test environments only to register mock or test templates. It directly modifies the internal template registry and is not thread-safe. The template is registered under its @ChangeTemplate annotation's id.

Parameters:

templateClass - The template class to register