Service Provider Framework

/**
 * Factory for creating optimized loop nodes
 * Implement this interface to provide custom loop optimization strategies
 */
public interface LoopNodeFactory {
    /** 
     * Creates a loop node for the given repeating node
     * @param repeatingNode The node that will be repeated in the loop
     * @return Optimized loop node implementation
     */
    LoopNode createLoopNode(RepeatingNode repeatingNode);
    
    /**
     * Returns the priority of this factory (higher priority takes precedence)
     * @return Priority value, default is 0
     */
    default int getPriority() {
        return 0;
    }
}

// Custom loop node factory implementation
public class MyCustomLoopNodeFactory implements LoopNodeFactory {
    
    @Override
    public LoopNode createLoopNode(RepeatingNode repeatingNode) {
        return new MyOptimizedLoopNode(repeatingNode);
    }
    
    @Override
    public int getPriority() {
        return 100; // Higher priority than default
    }
}

// Register via META-INF/services/com.oracle.truffle.runtime.LoopNodeFactory

/**
 * Support for engine-level caching of compilation artifacts and metadata
 * Implement this interface to provide custom caching strategies
 */
public interface EngineCacheSupport {
    /**
     * Gets or creates a cached value for the given key
     * @param key Cache key (typically related to code structure)
     * @param valueSupplier Supplier to create value if not cached
     * @return Cached or newly created value
     */
    <T> T getEngineCache(Object key, Supplier<T> valueSupplier);
    
    /**
     * Clears all cached values for this engine
     */
    void clearEngineCache();
    
    /**
     * Gets cache statistics if available
     * @return Cache statistics or null if not supported
     */
    default CacheStatistics getStatistics() {
        return null;
    }
    
    /**
     * Returns the maximum cache size
     * @return Maximum number of entries or -1 if unlimited
     */
    default long getMaxCacheSize() {
        return -1;
    }
}

public class MyEngineCacheSupport implements EngineCacheSupport {
    private final ConcurrentHashMap<Object, Object> cache = new ConcurrentHashMap<>();
    
    @Override
    public <T> T getEngineCache(Object key, Supplier<T> valueSupplier) {
        return (T) cache.computeIfAbsent(key, k -> valueSupplier.get());
    }
    
    @Override
    public void clearEngineCache() {
        cache.clear();
    }
    
    @Override
    public long getMaxCacheSize() {
        return 10000;
    }
}

/**
 * Integration point for custom type systems
 * Allows languages to provide type information to the runtime
 */
public interface TruffleTypes {
    /**
     * Returns the Java class for a language value
     * @param value Language-specific value
     * @return Corresponding Java class
     */
    Class<?> getJavaClass(Object value);
    
    /**
     * Returns the Java class name for a language value
     * @param value Language-specific value  
     * @return Java class name string
     */
    String getJavaClassName(Object value);
    
    /**
     * Checks if a value is of a specific type
     * @param value Value to check
     * @param type Type to check against
     * @return True if value is of the specified type
     */
    default boolean isType(Object value, Class<?> type) {
        return type.isInstance(value);
    }
    
    /**
     * Converts a value to a specific type if possible
     * @param value Value to convert
     * @param targetType Target type
     * @return Converted value or null if conversion not possible
     */
    default <T> T convertTo(Object value, Class<T> targetType) {
        if (targetType.isInstance(value)) {
            return targetType.cast(value);
        }
        return null;
    }
}

public class MyLanguageTypes implements TruffleTypes {
    
    @Override
    public Class<?> getJavaClass(Object value) {
        if (value instanceof MyLanguageNumber) {
            return Number.class;
        } else if (value instanceof MyLanguageString) {
            return String.class;
        }
        return Object.class;
    }
    
    @Override
    public String getJavaClassName(Object value) {
        return getJavaClass(value).getName();
    }
    
    @Override
    public <T> T convertTo(Object value, Class<T> targetType) {
        if (value instanceof MyLanguageNumber && targetType == Integer.class) {
            return targetType.cast(((MyLanguageNumber) value).intValue());
        }
        return TruffleTypes.super.convertTo(value, targetType);
    }
}

/**
 * Handler for managing compilation flood control
 * Implement to provide custom strategies for managing compilation load
 */
public interface FloodControlHandler {
    /**
     * Checks if compilation should be allowed for the given call target
     * @param callTarget The call target requesting compilation
     * @return True if compilation should proceed, false to defer
     */
    boolean allowCompilation(OptimizedCallTarget callTarget);
    
    /**
     * Notifies that a compilation request was deferred
     * @param callTarget The call target that was deferred
     * @param reason Reason for deferral
     */
    default void onCompilationDeferred(OptimizedCallTarget callTarget, String reason) {
        // Default implementation does nothing
    }
    
    /**
     * Notifies that compilation started for a call target
     * @param callTarget The call target being compiled
     */
    default void onCompilationStarted(OptimizedCallTarget callTarget) {
        // Default implementation does nothing
    }
    
    /**
     * Notifies that compilation finished for a call target
     * @param callTarget The call target that finished compilation
     * @param success True if compilation was successful
     */
    default void onCompilationFinished(OptimizedCallTarget callTarget, boolean success) {
        // Default implementation does nothing
    }
    
    /**
     * Returns the current compilation load (0.0 to 1.0)
     * @return Load factor where 1.0 means fully loaded
     */
    default double getCurrentLoad() {
        return 0.0;
    }
}

public class MyFloodControlHandler implements FloodControlHandler {
    private final AtomicInteger activeCompilations = new AtomicInteger();
    private static final int MAX_CONCURRENT_COMPILATIONS = 4;
    
    @Override
    public boolean allowCompilation(OptimizedCallTarget callTarget) {
        int current = activeCompilations.get();
        if (current >= MAX_CONCURRENT_COMPILATIONS) {
            return false;
        }
        return activeCompilations.compareAndSet(current, current + 1);
    }
    
    @Override
    public void onCompilationFinished(OptimizedCallTarget callTarget, boolean success) {
        activeCompilations.decrementAndGet();
    }
    
    @Override
    public double getCurrentLoad() {
        return (double) activeCompilations.get() / MAX_CONCURRENT_COMPILATIONS;
    }
}

com.example.MyCustomLoopNodeFactory
com.example.MyEngineCacheSupport  
com.example.MyLanguageTypes
com.example.MyFloodControlHandler

// Access services through the runtime
TruffleRuntime runtime = Truffle.getRuntime();

// Services are automatically discovered and used by the runtime
// No direct API for accessing individual services

public interface CacheStatistics {
    /** Returns the number of cache hits */
    long getHitCount();
    
    /** Returns the number of cache misses */
    long getMissCount();
    
    /** Returns the current number of cached entries */
    long getSize();
    
    /** Returns the cache hit rate (0.0 to 1.0) */
    double getHitRate();
    
    /** Returns the average time to load a value (in nanoseconds) */
    double getAverageLoadTime();
}

public interface Supplier<T> {
    /** Gets a result */
    T get();
}