com.oracle.truffle.api.instrumentation

Class TruffleInstrument

java.lang.Object

com.oracle.truffle.api.instrumentation.TruffleInstrument

public abstract class TruffleInstrument
extends Object

The service provider interface (SPI) for Truffle instruments: clients of Truffle instrumentation that may observe and inject behavior into interpreters written using the Truffle framework.

Instrument implementation classes must use the TruffleInstrument.Registration annotation to provide required metadata and to enable automatic discovery of the implementation.

An instrument is created if at least one instrument option was specified or if a service was looked up. The Instrumenter available in the provided environment allows the instrument instance to bind listeners for execution and source events, as well as node factories for code injection at guest language code locations.

An instrument is disposed when the associated polyglot engine is disposed. All active bindings created by a disposed instrument become disposed automatically. The Instrumenter instance available in the provided environment may not be used after disposal.

Example for a simple expression coverage instrument:

@TruffleInstrument.Registration(id = CoverageExample.ID, services = Object.class)
public final class CoverageExample extends TruffleInstrument {

    public static final String ID = "test-coverage";

    private final Set<SourceSection> coverage = new HashSet<>();

    @Override
    protected void onCreate(final Env env) {
        SourceSectionFilter.Builder builder = SourceSectionFilter.newBuilder();
        SourceSectionFilter filter = builder.tagIs(StandardTags.ExpressionTag.class).build();
        Instrumenter instrumenter = env.getInstrumenter();
        instrumenter.attachExecutionEventFactory(filter,
                        new CoverageExampleEventFactory(env));
    }

    private class CoverageExampleEventFactory
                    implements ExecutionEventNodeFactory {

        private final Env env;

        CoverageExampleEventFactory(final Env env) {
            this.env = env;
        }

        public ExecutionEventNode create(final EventContext ec) {
            final PrintStream out = new PrintStream(env.out());
            return new ExecutionEventNode() {
                @CompilerDirectives.CompilationFinal private boolean visited;

                @Override
                public void onReturnValue(VirtualFrame vFrame, Object result) {
                    if (!visited) {
                        CompilerDirectives.transferToInterpreterAndInvalidate();
                        visited = true;
                        SourceSection src = ec.getInstrumentedSourceSection();
                        out.print(src.getCharIndex() + " ");
                        coverage.add(src);
                    }
                }
            };
        }
    }

}

Since:

0.12

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	TruffleInstrument.Env Access to instrumentation services as well as input, output, and error streams.
static interface	TruffleInstrument.Provider Used to register a TruffleInstrument using a ServiceLoader.
static interface	TruffleInstrument.Registration Annotation that registers an instrument implementations for automatic discovery.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	TruffleInstrument() Constructor for subclasses.

Method Summary

Modifier and Type	Method and Description
protected org.graalvm.options.OptionDescriptors	getOptionDescriptors() Returns a set of option descriptors that are supported by this instrument.
protected abstract void	onCreate(TruffleInstrument.Env env) Invoked once on each newly allocated TruffleInstrument instance.
protected void	onDispose(TruffleInstrument.Env env) Invoked once on an instance when it becomes disabled, possibly because the underlying engine has been closed.
protected void	onFinalize(TruffleInstrument.Env env) Invoked once on an instance just before all instruments and languages are going to be disposed, possibly because the underlying engine is going to be closed.

Methods inherited from class java.lang.Object

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

Constructor Detail

TruffleInstrument

protected TruffleInstrument()

Constructor for subclasses.

Since:

0.12

Method Detail

onCreate

protected abstract void onCreate(TruffleInstrument.Env env)

Invoked once on each newly allocated TruffleInstrument instance.

The method may register additional services - e.g. objects to be exposed via lookup query. For example to expose a debugger one could define an abstract debugger controller:

public abstract class DebuggerController {
    DebuggerController() {
    }

    public abstract void installBreakpoint(int i, Callback callback);

    public abstract void stepInto(Callback callback);

    public abstract void stepOut(Callback callback);

    public abstract void stepOver(Callback callback);

    public interface Callback {

        void halted(DebuggerController debugger, EventContext haltedAt);

    }

}

and declare it as a service associated with the instrument, implement it, instantiate and register in own's instrument onCreate method:

@TruffleInstrument.Registration(id = DebuggerExample.ID, services = DebuggerController.class)
public final class DebuggerExample extends TruffleInstrument {
    private Controller controller;

    @Override
    protected void onCreate(Env env) {
        assert this.controller == null;
        this.controller = new Controller(env.getInstrumenter());
        env.registerService(controller);
    }

    private static final class Controller extends DebuggerController {
        private final Instrumenter instrumenter;
        private EventBinding<?> stepping;
        private Callback currentStatementCallback;

        Controller(Instrumenter instrumenter) {
            this.instrumenter = instrumenter;
        }

    }
}

Parameters:

env - environment information for the instrument

Since:

0.12

See Also:

TruffleInstrument.Env.getInstrumenter()

onFinalize

protected void onFinalize(TruffleInstrument.Env env)

Invoked once on an instance just before all instruments and languages are going to be disposed, possibly because the underlying engine is going to be closed. This method is called before TruffleInstrument.onDispose(Env) and the instrument must remain usable after finalization. The instrument can prepare for disposal while still having other instruments not disposed yet.

Parameters:

env - environment information for the instrument

Since:

19.0

onDispose

protected void onDispose(TruffleInstrument.Env env)

Invoked once on an instance when it becomes disabled, possibly because the underlying engine has been closed. A disposed instance is no longer usable. If the instrument is re-enabled, the engine will create a new instance.

Parameters:

env - environment information for the instrument

Since:

0.12

getOptionDescriptors

protected org.graalvm.options.OptionDescriptors getOptionDescriptors()

Returns a set of option descriptors that are supported by this instrument. Option values are accessible using the environment when the instrument is created. By default no options are available for an instrument. Options returned by this method must specify the instrument id as name prefix for each option. For example if the id of the instrument is "debugger" then a valid option name would be "debugger.Enabled". The instrument will automatically be created if one of the specified options was provided by the engine. To construct option descriptors from a list then OptionDescriptors.create(List) can be used.

Since:

0.27

See Also:

For an example of declaring the option descriptor using an annotation.