DSL deferred execution #482
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| /* | ||
| * Copyright 2016 The Apache Software Foundation. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package org.apache.brooklyn.camp.brooklyn.spi.dsl; | ||
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| import org.apache.brooklyn.util.core.task.DeferredSupplier; | ||
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| /** | ||
| * Marker interface so the evaluator can tell apart objects which are {@link DeferredSupplier} | ||
| * but which expect DSL methods called on them instead of the value they supply. | ||
| */ | ||
| public interface DslCallable { | ||
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| } | ||
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| /* | ||
| * Copyright 2016 The Apache Software Foundation. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| package org.apache.brooklyn.camp.brooklyn.spi.dsl; | ||
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| import java.lang.reflect.InvocationTargetException; | ||
| import java.util.List; | ||
| import java.util.concurrent.Callable; | ||
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| import org.apache.brooklyn.api.mgmt.Task; | ||
| import org.apache.brooklyn.camp.brooklyn.spi.dsl.methods.BrooklynDslCommon; | ||
| import org.apache.brooklyn.core.entity.EntityInternal; | ||
| import org.apache.brooklyn.core.mgmt.BrooklynTaskTags; | ||
| import org.apache.brooklyn.util.core.task.Tasks; | ||
| import org.apache.brooklyn.util.exceptions.Exceptions; | ||
| import org.apache.brooklyn.util.guava.Maybe; | ||
| import org.apache.brooklyn.util.javalang.Reflections; | ||
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| import com.google.common.base.Joiner; | ||
| import com.google.common.base.Objects; | ||
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| public class DslDeferredFunctionCall extends BrooklynDslDeferredSupplier<Object> { | ||
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| private static final long serialVersionUID = 3243262633795112155L; | ||
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| // TODO should this be some of the super types? | ||
| private BrooklynDslDeferredSupplier<?> object; | ||
| private String fnName; | ||
| private List<?> args; | ||
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| public DslDeferredFunctionCall(BrooklynDslDeferredSupplier<?> o, String fn, List<Object> args) { | ||
| this.object = o; | ||
| this.fnName = fn; | ||
| this.args = args; | ||
| } | ||
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| @Override | ||
| public Maybe<Object> getImmediately() { | ||
| Maybe<?> obj = resolveImmediate(object); | ||
| if (obj.isPresent()) { | ||
| if (obj.isNull()) { | ||
| throw new IllegalArgumentException("Deferred function call, " + object + | ||
| " evaluates to null (when calling " + fnName + "(" + toString(args) + "))"); | ||
| } | ||
| return Maybe.of(invokeOn(obj.get())); | ||
| } | ||
| return Maybe.absent("Could not evaluate immediately " + object); | ||
| } | ||
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| @Override | ||
| public Task<Object> newTask() { | ||
| return Tasks.builder() | ||
| .displayName("Deferred function call " + object + "." + fnName + "(" + toString(args) + ")") | ||
| .tag(BrooklynTaskTags.TRANSIENT_TASK_TAG) | ||
| .dynamic(false) | ||
| .body(new Callable<Object>() { | ||
| @Override | ||
| public Object call() throws Exception { | ||
| Object obj = DslDeferredFunctionCall.this.resolveBlocking(object).orNull(); | ||
| if (obj == null) { | ||
| throw new IllegalArgumentException("Deferred function call, " + object + | ||
| " evaluates to null (when calling " + fnName + "(" + DslDeferredFunctionCall.toString(args) + "))"); | ||
| } | ||
| return invokeOn(obj); | ||
| } | ||
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| }).build(); | ||
| } | ||
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| protected Maybe<?> resolveImmediate(Object object) { | ||
| return resolve(object, true); | ||
| } | ||
| protected Maybe<?> resolveBlocking(Object object) { | ||
| return resolve(object, false); | ||
| } | ||
| protected Maybe<?> resolve(Object object, boolean immediate) { | ||
| if (object instanceof DslCallable || object == null) { | ||
| return Maybe.of(object); | ||
| } | ||
| Maybe<?> resultMaybe = Tasks.resolving(object, Object.class) | ||
|
Contributor
There was a problem hiding this comment. How is this code reachable? This class is only constructed when |
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| .context(((EntityInternal)entity()).getExecutionContext()) | ||
| .deep(true) | ||
| .immediately(immediate) | ||
| .recursive(false) | ||
| .getMaybe(); | ||
| if (resultMaybe.isAbsent()) { | ||
| return resultMaybe; | ||
| } else { | ||
| // No nice way to figure out whether the object is deferred. Try to resolve it | ||
| // until it matches the input value as a poor man's replacement. | ||
| Object result = resultMaybe.get(); | ||
| if (result == object) { | ||
| return resultMaybe; | ||
| } else { | ||
| return resolve(result, immediate); | ||
| } | ||
| } | ||
| } | ||
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| protected Object invokeOn(Object obj) { | ||
| return invokeOn(obj, fnName, args); | ||
| } | ||
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| protected static Object invokeOn(Object obj, String fnName, List<?> args) { | ||
| checkCallAllowed(obj, fnName, args); | ||
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| Maybe<Object> v; | ||
| try { | ||
| v = Reflections.invokeMethodFromArgs(obj, fnName, args); | ||
| } catch (IllegalArgumentException | IllegalAccessException | InvocationTargetException e) { | ||
| Exceptions.propagateIfFatal(e); | ||
| throw Exceptions.propagate(new InvocationTargetException(e, "Error invoking '"+fnName+"("+toString(args)+")' on '"+obj+"'")); | ||
| } | ||
| if (v.isPresent()) { | ||
| // Value is most likely another BrooklynDslDeferredSupplier - let the caller handle it, | ||
| return v.get(); | ||
| } else { | ||
| throw new IllegalArgumentException("No such function '"+fnName+"("+toString(args)+")' on "+obj); | ||
| } | ||
| } | ||
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| private static void checkCallAllowed(Object obj, String fnName2, List<?> args2) { | ||
| Class<?> clazz; | ||
| if (obj instanceof Class) { | ||
| clazz = (Class<?>)obj; | ||
| } else { | ||
| clazz = obj.getClass(); | ||
| } | ||
| if (!(clazz.getPackage().getName().startsWith(BrooklynDslCommon.class.getPackage().getName()))) | ||
| throw new IllegalArgumentException("Not permitted to invoke function on '"+clazz+"' (outside allowed package scope)"); | ||
| } | ||
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| @Override | ||
| public int hashCode() { | ||
| return Objects.hashCode(object, fnName, args); | ||
| } | ||
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| @Override | ||
| public boolean equals(Object obj) { | ||
| if (this == obj) return true; | ||
| if (obj == null || getClass() != obj.getClass()) return false; | ||
| DslDeferredFunctionCall that = DslDeferredFunctionCall.class.cast(obj); | ||
| return Objects.equal(this.object, that.object) && | ||
| Objects.equal(this.fnName, that.fnName) && | ||
| Objects.equal(this.args, that.args); | ||
| } | ||
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| @Override | ||
| public String toString() { | ||
| return object + "." + fnName + "(" + toString(args) + ")"; | ||
| } | ||
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| private static String toString(List<?> args) { | ||
| if (args == null) return ""; | ||
| return Joiner.on(", ").join(args); | ||
| } | ||
| } | ||
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I'm considering changing this to an annotation. When applied on:
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I like this idea. Do you want to make it part of this PR or do it subsequently?
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This one. Don't want to introduce APIs that will go away in master.
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After spiking the changes decided to keep
DslCallableinterface for first case and introduce aDslAccessibleannotation for second. They have different use-cases, better not to mix them in the same annotation.Will send an email to dev@brooklyn.apache.org discussing the
DslAccessiblechange and implement it in a separate PR.