models-interactions/model-actors/actorServiceProvider/src/main/java/org/onap/policy/controlloop/actorserviceprovider/impl/OperationPartial.java

   1 /*-
   2  * ============LICENSE_START=======================================================
   3  * ONAP
   4  * ================================================================================
   5  * Copyright (C) 2020 AT&T Intellectual Property. All rights reserved.
   6  * ================================================================================
   7  * Licensed under the Apache License, Version 2.0 (the "License");
   8  * you may not use this file except in compliance with the License.
   9  * You may obtain a copy of the License at
  10  *
  11  *      http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  * ============LICENSE_END=========================================================
  19  */
  20
  21 package org.onap.policy.controlloop.actorserviceprovider.impl;
  22
  23 import java.util.ArrayDeque;
  24 import java.util.ArrayList;
  25 import java.util.Arrays;
  26 import java.util.HashMap;
  27 import java.util.LinkedHashMap;
  28 import java.util.LinkedList;
  29 import java.util.List;
  30 import java.util.Map;
  31 import java.util.Queue;
  32 import java.util.UUID;
  33 import java.util.concurrent.CancellationException;
  34 import java.util.concurrent.CompletableFuture;
  35 import java.util.concurrent.CompletionException;
  36 import java.util.concurrent.Executor;
  37 import java.util.concurrent.TimeUnit;
  38 import java.util.concurrent.TimeoutException;
  39 import java.util.function.BiConsumer;
  40 import java.util.function.Function;
  41 import java.util.function.Supplier;
  42 import java.util.function.UnaryOperator;
  43 import lombok.AccessLevel;
  44 import lombok.Getter;
  45 import lombok.Setter;
  46 import org.onap.policy.common.endpoints.event.comm.Topic.CommInfrastructure;
  47 import org.onap.policy.common.endpoints.utils.NetLoggerUtil;
  48 import org.onap.policy.common.endpoints.utils.NetLoggerUtil.EventType;
  49 import org.onap.policy.common.utils.coder.Coder;
  50 import org.onap.policy.common.utils.coder.CoderException;
  51 import org.onap.policy.common.utils.coder.StandardCoder;
  52 import org.onap.policy.controlloop.ControlLoopOperation;
  53 import org.onap.policy.controlloop.actorserviceprovider.CallbackManager;
  54 import org.onap.policy.controlloop.actorserviceprovider.Operation;
  55 import org.onap.policy.controlloop.actorserviceprovider.OperationOutcome;
  56 import org.onap.policy.controlloop.actorserviceprovider.parameters.ControlLoopOperationParams;
  57 import org.onap.policy.controlloop.actorserviceprovider.parameters.OperatorConfig;
  58 import org.onap.policy.controlloop.actorserviceprovider.pipeline.PipelineControllerFuture;
  59 import org.onap.policy.controlloop.policy.PolicyResult;
  60 import org.slf4j.Logger;
  61 import org.slf4j.LoggerFactory;
  62
  63 /**
  64  * Partial implementation of an operator. In general, it's preferable that subclasses
  65  * would override {@link #startOperationAsync(int, OperationOutcome)
  66  * startOperationAsync()}. However, if that proves to be too difficult, then they can
  67  * simply override {@link #doOperation(int, OperationOutcome) doOperation()}. In addition,
  68  * if the operation requires any preprocessor steps, the subclass may choose to override
  69  * {@link #startPreprocessorAsync()}.
  70  * <p/>
  71  * The futures returned by the methods within this class can be canceled, and will
  72  * propagate the cancellation to any subtasks. Thus it is also expected that any futures
  73  * returned by overridden methods will do the same. Of course, if a class overrides
  74  * {@link #doOperation(int, OperationOutcome) doOperation()}, then there's little that can
  75  * be done to cancel that particular operation.
  76  * <p/>
  77  * In general tasks in a pipeline are executed by the same thread. However, the following
  78  * should always be executed via the executor specified in "params":
  79  * <ul>
  80  * <li>start callback</li>
  81  * <li>completion callback</li>
  82  * <li>controller completion (i.e., delayedComplete())</li>
  83  * </ul>
  84  */
  85 public abstract class OperationPartial implements Operation {
  86     private static final Logger logger = LoggerFactory.getLogger(OperationPartial.class);
  87     private static final Coder coder = new StandardCoder();
  88
  89     public static final String GUARD_ACTOR_NAME = "GUARD";
  90     public static final String GUARD_OPERATION_NAME = "Decision";
  91     public static final long DEFAULT_RETRY_WAIT_MS = 1000L;
  92
  93     private final OperatorConfig config;
  94
  95     /**
  96      * Operation parameters.
  97      */
  98     protected final ControlLoopOperationParams params;
  99
 100     @Getter
 101     private final String fullName;
 102
 103     @Getter
 104     @Setter(AccessLevel.PROTECTED)
 105     private String subRequestId;
 106
 107     @Getter
 108     private final List<String> propertyNames;
 109
 110     /**
 111      * Values for the properties identified by {@link #getPropertyNames()}.
 112      */
 113     private final Map<String, Object> properties = new HashMap<>();
 114
 115
 116     /**
 117      * Constructs the object.
 118      *
 119      * @param params operation parameters
 120      * @param config configuration for this operation
 121      * @param propertyNames names of properties required by this operation
 122      */
 123     public OperationPartial(ControlLoopOperationParams params, OperatorConfig config, List<String> propertyNames) {
 124         this.params = params;
 125         this.config = config;
 126         this.fullName = params.getActor() + "." + params.getOperation();
 127         this.propertyNames = propertyNames;
 128     }
 129
 130     public Executor getBlockingExecutor() {
 131         return config.getBlockingExecutor();
 132     }
 133
 134     public String getActorName() {
 135         return params.getActor();
 136     }
 137
 138     public String getName() {
 139         return params.getOperation();
 140     }
 141
 142     /**
 143      * Sets a property.
 144      *
 145      * @param name property name
 146      * @param value new value
 147      */
 148     public void setProperty(String name, Object value) {
 149         properties.put(name, value);
 150     }
 151
 152     /**
 153      * Gets a property's value.
 154      *
 155      * @param name name of the property of interest
 156      * @return the property's value, or {@code null} if it has no value
 157      */
 158     @SuppressWarnings("unchecked")
 159     public <T> T getProperty(String name) {
 160         return (T) properties.get(name);
 161     }
 162
 163     @Override
 164     public CompletableFuture<OperationOutcome> start() {
 165         // allocate a controller for the entire operation
 166         final PipelineControllerFuture<OperationOutcome> controller = new PipelineControllerFuture<>();
 167
 168         CompletableFuture<OperationOutcome> preproc = startPreprocessorAsync();
 169         if (preproc == null) {
 170             // no preprocessor required - just start the operation
 171             return startOperationAttempt(controller, 1);
 172         }
 173
 174         /*
 175          * Do preprocessor first and then, if successful, start the operation. Note:
 176          * operations create their own outcome, ignoring the outcome from any previous
 177          * steps.
 178          *
 179          * Wrap the preprocessor to ensure "stop" is propagated to it.
 180          */
 181         // @formatter:off
 182         controller.wrap(preproc)
 183                         .exceptionally(fromException("preprocessor of operation"))
 184                         .thenCompose(handlePreprocessorFailure(controller))
 185                         .thenCompose(unusedOutcome -> startOperationAttempt(controller, 1))
 186                         .whenCompleteAsync(controller.delayedComplete(), params.getExecutor());
 187         // @formatter:on
 188
 189         return controller;
 190     }
 191
 192     /**
 193      * Handles a failure in the preprocessor pipeline. If a failure occurred, then it
 194      * invokes the call-backs, marks the controller complete, and returns an incomplete
 195      * future, effectively halting the pipeline. Otherwise, it returns the outcome that it
 196      * received.
 197      * <p/>
 198      * Assumes that no callbacks have been invoked yet.
 199      *
 200      * @param controller pipeline controller
 201      * @return a function that checks the outcome status and continues, if successful, or
 202      *         indicates a failure otherwise
 203      */
 204     private Function<OperationOutcome, CompletableFuture<OperationOutcome>> handlePreprocessorFailure(
 205                     PipelineControllerFuture<OperationOutcome> controller) {
 206
 207         return outcome -> {
 208
 209             if (isSuccess(outcome)) {
 210                 logger.info("{}: preprocessor succeeded for {}", getFullName(), params.getRequestId());
 211                 return CompletableFuture.completedFuture(outcome);
 212             }
 213
 214             logger.warn("preprocessor failed, discontinuing operation {} for {}", getFullName(), params.getRequestId());
 215
 216             final Executor executor = params.getExecutor();
 217             final CallbackManager callbacks = new CallbackManager();
 218
 219             // propagate "stop" to the callbacks
 220             controller.add(callbacks);
 221
 222             final OperationOutcome outcome2 = params.makeOutcome();
 223
 224             // TODO need a FAILURE_MISSING_DATA (e.g., A&AI)
 225
 226             outcome2.setFinalOutcome(true);
 227             outcome2.setResult(PolicyResult.FAILURE_GUARD);
 228             outcome2.setMessage(outcome != null ? outcome.getMessage() : null);
 229
 230             // @formatter:off
 231             CompletableFuture.completedFuture(outcome2)
 232                             .whenCompleteAsync(callbackStarted(callbacks), executor)
 233                             .whenCompleteAsync(callbackCompleted(callbacks), executor)
 234                             .whenCompleteAsync(controller.delayedComplete(), executor);
 235             // @formatter:on
 236
 237             return new CompletableFuture<>();
 238         };
 239     }
 240
 241     /**
 242      * Invokes the operation's preprocessor step(s) as a "future". This method simply
 243      * returns {@code null}.
 244      * <p/>
 245      * This method assumes the following:
 246      * <ul>
 247      * <li>the operator is alive</li>
 248      * <li>exceptions generated within the pipeline will be handled by the invoker</li>
 249      * </ul>
 250      *
 251      * @return a function that will start the preprocessor and returns its outcome, or
 252      *         {@code null} if this operation needs no preprocessor
 253      */
 254     protected CompletableFuture<OperationOutcome> startPreprocessorAsync() {
 255         return null;
 256     }
 257
 258     /**
 259      * Invokes the operation's guard step(s) as a "future".
 260      * <p/>
 261      * This method assumes the following:
 262      * <ul>
 263      * <li>the operator is alive</li>
 264      * <li>exceptions generated within the pipeline will be handled by the invoker</li>
 265      * </ul>
 266      *
 267      * @return a function that will start the guard checks and returns its outcome, or
 268      *         {@code null} if this operation has no guard
 269      */
 270     protected CompletableFuture<OperationOutcome> startGuardAsync() {
 271         if (params.isPreprocessed()) {
 272             return null;
 273         }
 274
 275         // get the guard payload
 276         Map<String, Object> payload = makeGuardPayload();
 277
 278         /*
 279          * Note: can't use constants from actor.guard, because that would create a
 280          * circular dependency.
 281          */
 282         return params.toBuilder().actor(GUARD_ACTOR_NAME).operation(GUARD_OPERATION_NAME).retry(null).timeoutSec(null)
 283                         .payload(payload).build().start();
 284     }
 285
 286     /**
 287      * Creates a payload to execute a guard operation.
 288      *
 289      * @return a new guard payload
 290      */
 291     protected Map<String, Object> makeGuardPayload() {
 292         // TODO delete this once preprocessing is done by the application
 293         Map<String, Object> guard = new LinkedHashMap<>();
 294         guard.put("actor", params.getActor());
 295         guard.put("operation", params.getOperation());
 296         guard.put("target", params.getTargetEntity());
 297         guard.put("requestId", params.getRequestId());
 298
 299         String clname = params.getContext().getEvent().getClosedLoopControlName();
 300         if (clname != null) {
 301             guard.put("clname", clname);
 302         }
 303
 304         return guard;
 305     }
 306
 307     /**
 308      * Starts the operation attempt, with no preprocessor. When all retries complete, it
 309      * will complete the controller.
 310      *
 311      * @param controller controller for all operation attempts
 312      * @param attempt attempt number, typically starting with 1
 313      * @return a future that will return the final result of all attempts
 314      */
 315     private CompletableFuture<OperationOutcome> startOperationAttempt(
 316                     PipelineControllerFuture<OperationOutcome> controller, int attempt) {
 317
 318         generateSubRequestId(attempt);
 319
 320         // propagate "stop" to the operation attempt
 321         controller.wrap(startAttemptWithoutRetries(attempt)).thenCompose(retryOnFailure(controller, attempt))
 322                         .whenCompleteAsync(controller.delayedComplete(), params.getExecutor());
 323
 324         return controller;
 325     }
 326
 327     /**
 328      * Generates and sets {@link #subRequestId} to a new subrequest ID.
 329      * @param attempt attempt number, typically starting with 1
 330      */
 331     public void generateSubRequestId(int attempt) {
 332         // Note: this should be "protected", but that makes junits much messier
 333
 334         setSubRequestId(UUID.randomUUID().toString());
 335     }
 336
 337     /**
 338      * Starts the operation attempt, without doing any retries.
 339      *
 340      * @param params operation parameters
 341      * @param attempt attempt number, typically starting with 1
 342      * @return a future that will return the result of a single operation attempt
 343      */
 344     private CompletableFuture<OperationOutcome> startAttemptWithoutRetries(int attempt) {
 345
 346         logger.info("{}: start operation attempt {} for {}", getFullName(), attempt, params.getRequestId());
 347
 348         final Executor executor = params.getExecutor();
 349         final OperationOutcome outcome = params.makeOutcome();
 350         final CallbackManager callbacks = new CallbackManager();
 351
 352         // this operation attempt gets its own controller
 353         final PipelineControllerFuture<OperationOutcome> controller = new PipelineControllerFuture<>();
 354
 355         // propagate "stop" to the callbacks
 356         controller.add(callbacks);
 357
 358         // @formatter:off
 359         CompletableFuture<OperationOutcome> future = CompletableFuture.completedFuture(outcome)
 360                         .whenCompleteAsync(callbackStarted(callbacks), executor)
 361                         .thenCompose(controller.wrap(outcome2 -> startOperationAsync(attempt, outcome2)));
 362         // @formatter:on
 363
 364         // handle timeouts, if specified
 365         long timeoutMillis = getTimeoutMs(params.getTimeoutSec());
 366         if (timeoutMillis > 0) {
 367             logger.info("{}: set timeout to {}ms for {}", getFullName(), timeoutMillis, params.getRequestId());
 368             future = future.orTimeout(timeoutMillis, TimeUnit.MILLISECONDS);
 369         }
 370
 371         /*
 372          * Note: we re-invoke callbackStarted() just to be sure the callback is invoked
 373          * before callbackCompleted() is invoked.
 374          *
 375          * Note: no need to remove "callbacks" from the pipeline, as we're going to stop
 376          * the pipeline as the last step anyway.
 377          */
 378
 379         // @formatter:off
 380         future.exceptionally(fromException("operation"))
 381                     .thenApply(setRetryFlag(attempt))
 382                     .whenCompleteAsync(callbackStarted(callbacks), executor)
 383                     .whenCompleteAsync(callbackCompleted(callbacks), executor)
 384                     .whenCompleteAsync(controller.delayedComplete(), executor);
 385         // @formatter:on
 386
 387         return controller;
 388     }
 389
 390     /**
 391      * Determines if the outcome was successful.
 392      *
 393      * @param outcome outcome to examine
 394      * @return {@code true} if the outcome was successful
 395      */
 396     protected boolean isSuccess(OperationOutcome outcome) {
 397         return (outcome != null && outcome.getResult() == PolicyResult.SUCCESS);
 398     }
 399
 400     /**
 401      * Determines if the outcome was a failure for this operator.
 402      *
 403      * @param outcome outcome to examine, or {@code null}
 404      * @return {@code true} if the outcome is not {@code null} and was a failure
 405      *         <i>and</i> was associated with this operator, {@code false} otherwise
 406      */
 407     protected boolean isActorFailed(OperationOutcome outcome) {
 408         return (isSameOperation(outcome) && outcome.getResult() == PolicyResult.FAILURE);
 409     }
 410
 411     /**
 412      * Determines if the given outcome is for this operation.
 413      *
 414      * @param outcome outcome to examine
 415      * @return {@code true} if the outcome is for this operation, {@code false} otherwise
 416      */
 417     protected boolean isSameOperation(OperationOutcome outcome) {
 418         return OperationOutcome.isFor(outcome, getActorName(), getName());
 419     }
 420
 421     /**
 422      * Invokes the operation as a "future". This method simply invokes
 423      * {@link #doOperation()} using the {@link #blockingExecutor "blocking executor"},
 424      * returning the result via a "future".
 425      * <p/>
 426      * Note: if the operation uses blocking I/O, then it should <i>not</i> be run using
 427      * the executor in the "params", as that may bring the background thread pool to a
 428      * grinding halt. The {@link #blockingExecutor "blocking executor"} should be used
 429      * instead.
 430      * <p/>
 431      * This method assumes the following:
 432      * <ul>
 433      * <li>the operator is alive</li>
 434      * <li>verifyRunning() has been invoked</li>
 435      * <li>callbackStarted() has been invoked</li>
 436      * <li>the invoker will perform appropriate timeout checks</li>
 437      * <li>exceptions generated within the pipeline will be handled by the invoker</li>
 438      * </ul>
 439      *
 440      * @param attempt attempt number, typically starting with 1
 441      * @return a function that will start the operation and return its result when
 442      *         complete
 443      */
 444     protected CompletableFuture<OperationOutcome> startOperationAsync(int attempt, OperationOutcome outcome) {
 445
 446         return CompletableFuture.supplyAsync(() -> doOperation(attempt, outcome), getBlockingExecutor());
 447     }
 448
 449     /**
 450      * Low-level method that performs the operation. This can make the same assumptions
 451      * that are made by {@link #doOperationAsFuture()}. This particular method simply
 452      * throws an {@link UnsupportedOperationException}.
 453      *
 454      * @param attempt attempt number, typically starting with 1
 455      * @param operation the operation being performed
 456      * @return the outcome of the operation
 457      */
 458     protected OperationOutcome doOperation(int attempt, OperationOutcome operation) {
 459
 460         throw new UnsupportedOperationException("start operation " + getFullName());
 461     }
 462
 463     /**
 464      * Sets the outcome status to FAILURE_RETRIES, if the current operation outcome is
 465      * FAILURE, assuming the policy specifies retries and the retry count has been
 466      * exhausted.
 467      *
 468      * @param attempt latest attempt number, starting with 1
 469      * @return a function to get the next future to execute
 470      */
 471     private Function<OperationOutcome, OperationOutcome> setRetryFlag(int attempt) {
 472
 473         return origOutcome -> {
 474             // ensure we have a non-null outcome
 475             OperationOutcome outcome;
 476             if (origOutcome != null) {
 477                 outcome = origOutcome;
 478             } else {
 479                 logger.warn("{}: null outcome; treating as a failure for {}", getFullName(), params.getRequestId());
 480                 outcome = this.setOutcome(params.makeOutcome(), PolicyResult.FAILURE);
 481             }
 482
 483             // ensure correct actor/operation
 484             outcome.setActor(getActorName());
 485             outcome.setOperation(getName());
 486
 487             // determine if we should retry, based on the result
 488             if (outcome.getResult() != PolicyResult.FAILURE) {
 489                 // do not retry success or other failure types (e.g., exception)
 490                 outcome.setFinalOutcome(true);
 491                 return outcome;
 492             }
 493
 494             int retry = getRetry(params.getRetry());
 495             if (retry <= 0) {
 496                 // no retries were specified
 497                 outcome.setFinalOutcome(true);
 498
 499             } else if (attempt <= retry) {
 500                 // have more retries - not the final outcome
 501                 outcome.setFinalOutcome(false);
 502
 503             } else {
 504                 /*
 505                  * retries were specified and we've already tried them all - change to
 506                  * FAILURE_RETRIES
 507                  */
 508                 logger.info("operation {} retries exhausted for {}", getFullName(), params.getRequestId());
 509                 outcome.setResult(PolicyResult.FAILURE_RETRIES);
 510                 outcome.setFinalOutcome(true);
 511             }
 512
 513             return outcome;
 514         };
 515     }
 516
 517     /**
 518      * Restarts the operation if it was a FAILURE. Assumes that {@link #setRetryFlag(int)}
 519      * was previously invoked, and thus that the "operation" is not {@code null}.
 520      *
 521      * @param controller controller for all of the retries
 522      * @param attempt latest attempt number, starting with 1
 523      * @return a function to get the next future to execute
 524      */
 525     private Function<OperationOutcome, CompletableFuture<OperationOutcome>> retryOnFailure(
 526                     PipelineControllerFuture<OperationOutcome> controller, int attempt) {
 527
 528         return operation -> {
 529             if (!isActorFailed(operation)) {
 530                 // wrong type or wrong operation - just leave it as is
 531                 logger.info("not retrying operation {} for {}", getFullName(), params.getRequestId());
 532                 controller.complete(operation);
 533                 return new CompletableFuture<>();
 534             }
 535
 536             if (getRetry(params.getRetry()) <= 0) {
 537                 // no retries - already marked as FAILURE, so just return it
 538                 logger.info("operation {} no retries for {}", getFullName(), params.getRequestId());
 539                 controller.complete(operation);
 540                 return new CompletableFuture<>();
 541             }
 542
 543             /*
 544              * Retry the operation.
 545              */
 546             long waitMs = getRetryWaitMs();
 547             logger.info("retry operation {} in {}ms for {}", getFullName(), waitMs, params.getRequestId());
 548
 549             return sleep(waitMs, TimeUnit.MILLISECONDS)
 550                             .thenCompose(unused -> startOperationAttempt(controller, attempt + 1));
 551         };
 552     }
 553
 554     /**
 555      * Convenience method that starts a sleep(), running via a future.
 556      *
 557      * @param sleepTime time to sleep
 558      * @param unit time unit
 559      * @return a future that will complete when the sleep completes
 560      */
 561     protected CompletableFuture<Void> sleep(long sleepTime, TimeUnit unit) {
 562         if (sleepTime <= 0) {
 563             return CompletableFuture.completedFuture(null);
 564         }
 565
 566         return new CompletableFuture<Void>().completeOnTimeout(null, sleepTime, unit);
 567     }
 568
 569     /**
 570      * Converts an exception into an operation outcome, returning a copy of the outcome to
 571      * prevent background jobs from changing it.
 572      *
 573      * @param type type of item throwing the exception
 574      * @return a function that will convert an exception into an operation outcome
 575      */
 576     private Function<Throwable, OperationOutcome> fromException(String type) {
 577
 578         return thrown -> {
 579             OperationOutcome outcome = params.makeOutcome();
 580
 581             if (thrown instanceof CancellationException || thrown.getCause() instanceof CancellationException) {
 582                 // do not include exception in the message, as it just clutters the log
 583                 logger.warn("{} canceled {}.{} for {}", type, outcome.getActor(), outcome.getOperation(),
 584                                 params.getRequestId());
 585             } else {
 586                 logger.warn("exception thrown by {} {}.{} for {}", type, outcome.getActor(), outcome.getOperation(),
 587                                 params.getRequestId(), thrown);
 588             }
 589
 590             return setOutcome(outcome, thrown);
 591         };
 592     }
 593
 594     /**
 595      * Similar to {@link CompletableFuture#anyOf(CompletableFuture...)}, but it cancels
 596      * any outstanding futures when one completes.
 597      *
 598      * @param futureMakers function to make a future. If the function returns
 599      *        {@code null}, then no future is created for that function. On the other
 600      *        hand, if the function throws an exception, then the previously created
 601      *        functions are canceled and the exception is re-thrown
 602      * @return a future to cancel or await an outcome, or {@code null} if no futures were
 603      *         created. If this future is canceled, then all of the futures will be
 604      *         canceled
 605      */
 606     public CompletableFuture<OperationOutcome> anyOf(
 607                     @SuppressWarnings("unchecked") Supplier<CompletableFuture<OperationOutcome>>... futureMakers) {
 608
 609         return anyOf(Arrays.asList(futureMakers));
 610     }
 611
 612     /**
 613      * Similar to {@link CompletableFuture#anyOf(CompletableFuture...)}, but it cancels
 614      * any outstanding futures when one completes.
 615      *
 616      * @param futureMakers function to make a future. If the function returns
 617      *        {@code null}, then no future is created for that function. On the other
 618      *        hand, if the function throws an exception, then the previously created
 619      *        functions are canceled and the exception is re-thrown
 620      * @return a future to cancel or await an outcome, or {@code null} if no futures were
 621      *         created. If this future is canceled, then all of the futures will be
 622      *         canceled. Similarly, when this future completes, any incomplete futures
 623      *         will be canceled
 624      */
 625     public CompletableFuture<OperationOutcome> anyOf(List<Supplier<CompletableFuture<OperationOutcome>>> futureMakers) {
 626
 627         PipelineControllerFuture<OperationOutcome> controller = new PipelineControllerFuture<>();
 628
 629         CompletableFuture<OperationOutcome>[] futures =
 630                         attachFutures(controller, futureMakers, UnaryOperator.identity());
 631
 632         if (futures.length == 0) {
 633             // no futures were started
 634             return null;
 635         }
 636
 637         if (futures.length == 1) {
 638             return futures[0];
 639         }
 640
 641         CompletableFuture.anyOf(futures).thenApply(outcome -> (OperationOutcome) outcome)
 642                         .whenCompleteAsync(controller.delayedComplete(), params.getExecutor());
 643
 644         return controller;
 645     }
 646
 647     /**
 648      * Similar to {@link CompletableFuture#allOf(CompletableFuture...)}.
 649      *
 650      * @param futureMakers function to make a future. If the function returns
 651      *        {@code null}, then no future is created for that function. On the other
 652      *        hand, if the function throws an exception, then the previously created
 653      *        functions are canceled and the exception is re-thrown
 654      * @return a future to cancel or await an outcome, or {@code null} if no futures were
 655      *         created. If this future is canceled, then all of the futures will be
 656      *         canceled
 657      */
 658     public CompletableFuture<OperationOutcome> allOf(
 659                     @SuppressWarnings("unchecked") Supplier<CompletableFuture<OperationOutcome>>... futureMakers) {
 660
 661         return allOf(Arrays.asList(futureMakers));
 662     }
 663
 664     /**
 665      * Similar to {@link CompletableFuture#allOf(CompletableFuture...)}.
 666      *
 667      * @param futureMakers function to make a future. If the function returns
 668      *        {@code null}, then no future is created for that function. On the other
 669      *        hand, if the function throws an exception, then the previously created
 670      *        functions are canceled and the exception is re-thrown
 671      * @return a future to cancel or await an outcome, or {@code null} if no futures were
 672      *         created. If this future is canceled, then all of the futures will be
 673      *         canceled. Similarly, when this future completes, any incomplete futures
 674      *         will be canceled
 675      */
 676     public CompletableFuture<OperationOutcome> allOf(List<Supplier<CompletableFuture<OperationOutcome>>> futureMakers) {
 677         PipelineControllerFuture<OperationOutcome> controller = new PipelineControllerFuture<>();
 678
 679         Queue<OperationOutcome> outcomes = new LinkedList<>();
 680
 681         CompletableFuture<OperationOutcome>[] futures =
 682                         attachFutures(controller, futureMakers, future -> future.thenApply(outcome -> {
 683                             synchronized (outcomes) {
 684                                 outcomes.add(outcome);
 685                             }
 686                             return outcome;
 687                         }));
 688
 689         if (futures.length == 0) {
 690             // no futures were started
 691             return null;
 692         }
 693
 694         if (futures.length == 1) {
 695             return futures[0];
 696         }
 697
 698         // @formatter:off
 699         CompletableFuture.allOf(futures)
 700                         .thenApply(unused -> combineOutcomes(outcomes))
 701                         .whenCompleteAsync(controller.delayedComplete(), params.getExecutor());
 702         // @formatter:on
 703
 704         return controller;
 705     }
 706
 707     /**
 708      * Invokes the functions to create the futures and attaches them to the controller.
 709      *
 710      * @param controller master controller for all of the futures
 711      * @param futureMakers futures to be attached to the controller
 712      * @param adorn function that "adorns" the future, possible adding onto its pipeline.
 713      *        Returns the adorned future
 714      * @return an array of futures, possibly zero-length. If the array is of size one,
 715      *         then that one item should be returned instead of the controller
 716      */
 717     private CompletableFuture<OperationOutcome>[] attachFutures(PipelineControllerFuture<OperationOutcome> controller,
 718                     List<Supplier<CompletableFuture<OperationOutcome>>> futureMakers,
 719                     UnaryOperator<CompletableFuture<OperationOutcome>> adorn) {
 720
 721         if (futureMakers.isEmpty()) {
 722             @SuppressWarnings("unchecked")
 723             CompletableFuture<OperationOutcome>[] result = new CompletableFuture[0];
 724             return result;
 725         }
 726
 727         // the last, unadorned future that is created
 728         CompletableFuture<OperationOutcome> lastFuture = null;
 729
 730         List<CompletableFuture<OperationOutcome>> futures = new ArrayList<>(futureMakers.size());
 731
 732         // make each future
 733         for (var maker : futureMakers) {
 734             try {
 735                 CompletableFuture<OperationOutcome> future = maker.get();
 736                 if (future == null) {
 737                     continue;
 738                 }
 739
 740                 // propagate "stop" to the future
 741                 controller.add(future);
 742
 743                 futures.add(adorn.apply(future));
 744
 745                 lastFuture = future;
 746
 747             } catch (RuntimeException e) {
 748                 logger.warn("{}: exception creating 'future' for {}", getFullName(), params.getRequestId());
 749                 controller.cancel(false);
 750                 throw e;
 751             }
 752         }
 753
 754         @SuppressWarnings("unchecked")
 755         CompletableFuture<OperationOutcome>[] result = new CompletableFuture[futures.size()];
 756
 757         if (result.length == 1) {
 758             // special case - return the unadorned future
 759             result[0] = lastFuture;
 760             return result;
 761         }
 762
 763         return futures.toArray(result);
 764     }
 765
 766     /**
 767      * Combines the outcomes from a set of tasks.
 768      *
 769      * @param outcomes outcomes to be examined
 770      * @return the combined outcome
 771      */
 772     private OperationOutcome combineOutcomes(Queue<OperationOutcome> outcomes) {
 773
 774         // identify the outcome with the highest priority
 775         OperationOutcome outcome = outcomes.remove();
 776         int priority = detmPriority(outcome);
 777
 778         for (OperationOutcome outcome2 : outcomes) {
 779             int priority2 = detmPriority(outcome2);
 780
 781             if (priority2 > priority) {
 782                 outcome = outcome2;
 783                 priority = priority2;
 784             }
 785         }
 786
 787         logger.info("{}: combined outcome of tasks is {} for {}", getFullName(),
 788                         (outcome == null ? null : outcome.getResult()), params.getRequestId());
 789
 790         return outcome;
 791     }
 792
 793     /**
 794      * Determines the priority of an outcome based on its result.
 795      *
 796      * @param outcome outcome to examine, or {@code null}
 797      * @return the outcome's priority
 798      */
 799     protected int detmPriority(OperationOutcome outcome) {
 800         if (outcome == null || outcome.getResult() == null) {
 801             return 1;
 802         }
 803
 804         switch (outcome.getResult()) {
 805             case SUCCESS:
 806                 return 0;
 807
 808             case FAILURE_GUARD:
 809                 return 2;
 810
 811             case FAILURE_RETRIES:
 812                 return 3;
 813
 814             case FAILURE:
 815                 return 4;
 816
 817             case FAILURE_TIMEOUT:
 818                 return 5;
 819
 820             case FAILURE_EXCEPTION:
 821             default:
 822                 return 6;
 823         }
 824     }
 825
 826     /**
 827      * Performs a sequence of tasks, stopping if a task fails. A given task's future is
 828      * not created until the previous task completes. The pipeline returns the outcome of
 829      * the last task executed.
 830      *
 831      * @param futureMakers functions to make the futures
 832      * @return a future to cancel the sequence or await the outcome
 833      */
 834     public CompletableFuture<OperationOutcome> sequence(
 835                     @SuppressWarnings("unchecked") Supplier<CompletableFuture<OperationOutcome>>... futureMakers) {
 836
 837         return sequence(Arrays.asList(futureMakers));
 838     }
 839
 840     /**
 841      * Performs a sequence of tasks, stopping if a task fails. A given task's future is
 842      * not created until the previous task completes. The pipeline returns the outcome of
 843      * the last task executed.
 844      *
 845      * @param futureMakers functions to make the futures
 846      * @return a future to cancel the sequence or await the outcome, or {@code null} if
 847      *         there were no tasks to perform
 848      */
 849     public CompletableFuture<OperationOutcome> sequence(
 850                     List<Supplier<CompletableFuture<OperationOutcome>>> futureMakers) {
 851
 852         Queue<Supplier<CompletableFuture<OperationOutcome>>> queue = new ArrayDeque<>(futureMakers);
 853
 854         CompletableFuture<OperationOutcome> nextTask = getNextTask(queue);
 855         if (nextTask == null) {
 856             // no tasks
 857             return null;
 858         }
 859
 860         if (queue.isEmpty()) {
 861             // only one task - just return it rather than wrapping it in a controller
 862             return nextTask;
 863         }
 864
 865         /*
 866          * multiple tasks - need a controller to stop whichever task is currently
 867          * executing
 868          */
 869         final PipelineControllerFuture<OperationOutcome> controller = new PipelineControllerFuture<>();
 870         final Executor executor = params.getExecutor();
 871
 872         // @formatter:off
 873         controller.wrap(nextTask)
 874                     .thenCompose(nextTaskOnSuccess(controller, queue))
 875                     .whenCompleteAsync(controller.delayedComplete(), executor);
 876         // @formatter:on
 877
 878         return controller;
 879     }
 880
 881     /**
 882      * Executes the next task in the queue, if the previous outcome was successful.
 883      *
 884      * @param controller pipeline controller
 885      * @param taskQueue queue of tasks to be performed
 886      * @return a future to execute the remaining tasks, or the current outcome, if it's a
 887      *         failure, or if there are no more tasks
 888      */
 889     private Function<OperationOutcome, CompletableFuture<OperationOutcome>> nextTaskOnSuccess(
 890                     PipelineControllerFuture<OperationOutcome> controller,
 891                     Queue<Supplier<CompletableFuture<OperationOutcome>>> taskQueue) {
 892
 893         return outcome -> {
 894             if (!isSuccess(outcome)) {
 895                 // return the failure
 896                 return CompletableFuture.completedFuture(outcome);
 897             }
 898
 899             CompletableFuture<OperationOutcome> nextTask = getNextTask(taskQueue);
 900             if (nextTask == null) {
 901                 // no tasks - just return the success
 902                 return CompletableFuture.completedFuture(outcome);
 903             }
 904
 905             // @formatter:off
 906             return controller
 907                         .wrap(nextTask)
 908                         .thenCompose(nextTaskOnSuccess(controller, taskQueue));
 909             // @formatter:on
 910         };
 911     }
 912
 913     /**
 914      * Gets the next task from the queue, skipping those that are {@code null}.
 915      *
 916      * @param taskQueue task queue
 917      * @return the next task, or {@code null} if the queue is now empty
 918      */
 919     private CompletableFuture<OperationOutcome> getNextTask(
 920                     Queue<Supplier<CompletableFuture<OperationOutcome>>> taskQueue) {
 921
 922         Supplier<CompletableFuture<OperationOutcome>> maker;
 923
 924         while ((maker = taskQueue.poll()) != null) {
 925             CompletableFuture<OperationOutcome> future = maker.get();
 926             if (future != null) {
 927                 return future;
 928             }
 929         }
 930
 931         return null;
 932     }
 933
 934     /**
 935      * Sets the start time of the operation and invokes the callback to indicate that the
 936      * operation has started. Does nothing if the pipeline has been stopped.
 937      * <p/>
 938      * This assumes that the "outcome" is not {@code null}.
 939      *
 940      * @param callbacks used to determine if the start callback can be invoked
 941      * @return a function that sets the start time and invokes the callback
 942      */
 943     protected BiConsumer<OperationOutcome, Throwable> callbackStarted(CallbackManager callbacks) {
 944
 945         return (outcome, thrown) -> {
 946
 947             if (callbacks.canStart()) {
 948                 outcome.setSubRequestId(getSubRequestId());
 949                 outcome.setStart(callbacks.getStartTime());
 950                 outcome.setEnd(null);
 951
 952                 // pass a copy to the callback
 953                 OperationOutcome outcome2 = new OperationOutcome(outcome);
 954                 outcome2.setFinalOutcome(false);
 955                 params.callbackStarted(outcome2);
 956             }
 957         };
 958     }
 959
 960     /**
 961      * Sets the end time of the operation and invokes the callback to indicate that the
 962      * operation has completed. Does nothing if the pipeline has been stopped.
 963      * <p/>
 964      * This assumes that the "outcome" is not {@code null}.
 965      * <p/>
 966      * Note: the start time must be a reference rather than a plain value, because it's
 967      * value must be gotten on-demand, when the returned function is executed at a later
 968      * time.
 969      *
 970      * @param callbacks used to determine if the end callback can be invoked
 971      * @return a function that sets the end time and invokes the callback
 972      */
 973     protected BiConsumer<OperationOutcome, Throwable> callbackCompleted(CallbackManager callbacks) {
 974
 975         return (outcome, thrown) -> {
 976             if (callbacks.canEnd()) {
 977                 outcome.setSubRequestId(getSubRequestId());
 978                 outcome.setStart(callbacks.getStartTime());
 979                 outcome.setEnd(callbacks.getEndTime());
 980
 981                 // pass a copy to the callback
 982                 params.callbackCompleted(new OperationOutcome(outcome));
 983             }
 984         };
 985     }
 986
 987     /**
 988      * Sets an operation's outcome and message, based on a throwable.
 989      *
 990      * @param operation operation to be updated
 991      * @return the updated operation
 992      */
 993     public OperationOutcome setOutcome(OperationOutcome operation, Throwable thrown) {
 994         PolicyResult result = (isTimeout(thrown) ? PolicyResult.FAILURE_TIMEOUT : PolicyResult.FAILURE_EXCEPTION);
 995         return setOutcome(operation, result);
 996     }
 997
 998     /**
 999      * Sets an operation's outcome and default message based on the result.
1000      *
1001      * @param operation operation to be updated
1002      * @param result result of the operation
1003      * @return the updated operation
1004      */
1005     public OperationOutcome setOutcome(OperationOutcome operation, PolicyResult result) {
1006         logger.trace("{}: set outcome {} for {}", getFullName(), result, params.getRequestId());
1007         operation.setResult(result);
1008         operation.setMessage(result == PolicyResult.SUCCESS ? ControlLoopOperation.SUCCESS_MSG
1009                         : ControlLoopOperation.FAILED_MSG);
1010
1011         return operation;
1012     }
1013
1014     /**
1015      * Determines if a throwable is due to a timeout.
1016      *
1017      * @param thrown throwable of interest
1018      * @return {@code true} if the throwable is due to a timeout, {@code false} otherwise
1019      */
1020     protected boolean isTimeout(Throwable thrown) {
1021         if (thrown instanceof CompletionException) {
1022             thrown = thrown.getCause();
1023         }
1024
1025         return (thrown instanceof TimeoutException);
1026     }
1027
1028     /**
1029      * Logs a message. If the message is not of type, String, then it attempts to
1030      * pretty-print it into JSON before logging.
1031      *
1032      * @param direction IN or OUT
1033      * @param infra communication infrastructure on which it was published
1034      * @param source source name (e.g., the URL or Topic name)
1035      * @param message message to be logged
1036      * @return the JSON text that was logged
1037      */
1038     public <T> String logMessage(EventType direction, CommInfrastructure infra, String source, T message) {
1039         String json;
1040         try {
1041             json = prettyPrint(message);
1042
1043         } catch (IllegalArgumentException e) {
1044             String type = (direction == EventType.IN ? "response" : "request");
1045             logger.warn("cannot pretty-print {}", type, e);
1046             json = message.toString();
1047         }
1048
1049         logger.info("[{}|{}|{}|]{}{}", direction, infra, source, NetLoggerUtil.SYSTEM_LS, json);
1050
1051         return json;
1052     }
1053
1054     /**
1055      * Converts a message to a "pretty-printed" String using the operation's normal
1056      * serialization provider (i.e., it's <i>coder</i>).
1057      *
1058      * @param message response to be logged
1059      * @return the JSON text that was logged
1060      * @throws IllegalArgumentException if the message cannot be converted
1061      */
1062     public <T> String prettyPrint(T message) {
1063         if (message == null) {
1064             return null;
1065         } else if (message instanceof String) {
1066             return message.toString();
1067         } else {
1068             try {
1069                 return getCoder().encode(message, true);
1070             } catch (CoderException e) {
1071                 throw new IllegalArgumentException("cannot encode message", e);
1072             }
1073         }
1074     }
1075
1076     // these may be overridden by subclasses or junit tests
1077
1078     /**
1079      * Gets the retry count.
1080      *
1081      * @param retry retry, extracted from the parameters, or {@code null}
1082      * @return the number of retries, or {@code 0} if no retries were specified
1083      */
1084     protected int getRetry(Integer retry) {
1085         return (retry == null ? 0 : retry);
1086     }
1087
1088     /**
1089      * Gets the retry wait, in milliseconds.
1090      *
1091      * @return the retry wait, in milliseconds
1092      */
1093     protected long getRetryWaitMs() {
1094         return DEFAULT_RETRY_WAIT_MS;
1095     }
1096
1097     /**
1098      * Gets the operation timeout.
1099      *
1100      * @param timeoutSec timeout, in seconds, extracted from the parameters, or
1101      *        {@code null}
1102      * @return the operation timeout, in milliseconds, or {@code 0} if no timeout was
1103      *         specified
1104      */
1105     protected long getTimeoutMs(Integer timeoutSec) {
1106         return (timeoutSec == null ? 0 : TimeUnit.MILLISECONDS.convert(timeoutSec, TimeUnit.SECONDS));
1107     }
1108
1109     // these may be overridden by junit tests
1110
1111     protected Coder getCoder() {
1112         return coder;
1113     }
1114 }