001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.procedure2;
019
020import java.io.IOException;
021import java.util.Arrays;
022import java.util.List;
023import java.util.Map;
024import java.util.concurrent.ThreadLocalRandom;
025import org.apache.hadoop.hbase.exceptions.TimeoutIOException;
026import org.apache.hadoop.hbase.metrics.Counter;
027import org.apache.hadoop.hbase.metrics.Histogram;
028import org.apache.hadoop.hbase.procedure2.store.ProcedureStore;
029import org.apache.hadoop.hbase.procedure2.util.StringUtils;
030import org.apache.hadoop.hbase.security.User;
031import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
032import org.apache.hadoop.hbase.util.NonceKey;
033import org.apache.yetus.audience.InterfaceAudience;
034import org.slf4j.Logger;
035import org.slf4j.LoggerFactory;
036
037import org.apache.hadoop.hbase.shaded.protobuf.generated.ProcedureProtos;
038import org.apache.hadoop.hbase.shaded.protobuf.generated.ProcedureProtos.ProcedureState;
039
040/**
041 * Base Procedure class responsible for Procedure Metadata; e.g. state, submittedTime, lastUpdate,
042 * stack-indexes, etc.
043 * <p/>
044 * Procedures are run by a {@link ProcedureExecutor} instance. They are submitted and then the
045 * ProcedureExecutor keeps calling {@link #execute(Object)} until the Procedure is done. Execute may
046 * be called multiple times in the case of failure or a restart, so code must be idempotent. The
047 * return from an execute call is either: null to indicate we are done; ourself if there is more to
048 * do; or, a set of sub-procedures that need to be run to completion before the framework resumes
049 * our execution.
050 * <p/>
051 * The ProcedureExecutor keeps its notion of Procedure State in the Procedure itself; e.g. it stamps
052 * the Procedure as INITIALIZING, RUNNABLE, SUCCESS, etc. Here are some of the States defined in the
053 * ProcedureState enum from protos:
054 * <ul>
055 * <li>{@link #isFailed()} A procedure has executed at least once and has failed. The procedure may
056 * or may not have rolled back yet. Any procedure in FAILED state will be eventually moved to
057 * ROLLEDBACK state.</li>
058 * <li>{@link #isSuccess()} A procedure is completed successfully without exception.</li>
059 * <li>{@link #isFinished()} As a procedure in FAILED state will be tried forever for rollback, only
060 * condition when scheduler/ executor will drop procedure from further processing is when procedure
061 * state is ROLLEDBACK or isSuccess() returns true. This is a terminal state of the procedure.</li>
062 * <li>{@link #isWaiting()} - Procedure is in one of the two waiting states
063 * ({@link ProcedureState#WAITING}, {@link ProcedureState#WAITING_TIMEOUT}).</li>
064 * </ul>
065 * NOTE: These states are of the ProcedureExecutor. Procedure implementations in turn can keep their
066 * own state. This can lead to confusion. Try to keep the two distinct.
067 * <p/>
068 * rollback() is called when the procedure or one of the sub-procedures has failed. The rollback
069 * step is supposed to cleanup the resources created during the execute() step. In case of failure
070 * and restart, rollback() may be called multiple times, so again the code must be idempotent.
071 * <p/>
072 * Procedure can be made respect a locking regime. It has acquire/release methods as well as an
073 * {@link #hasLock()}. The lock implementation is up to the implementor. If an entity needs to be
074 * locked for the life of a procedure -- not just the calls to execute -- then implementations
075 * should say so with the {@link #holdLock(Object)} method.
076 * <p/>
077 * And since we need to restore the lock when restarting to keep the logic correct(HBASE-20846), the
078 * implementation is a bit tricky so we add some comments hrre about it.
079 * <ul>
080 * <li>Make {@link #hasLock()} method final, and add a {@link #locked} field in Procedure to record
081 * whether we have the lock. We will set it to {@code true} in
082 * {@link #doAcquireLock(Object, ProcedureStore)} and to {@code false} in
083 * {@link #doReleaseLock(Object, ProcedureStore)}. The sub classes do not need to manage it any
084 * more.</li>
085 * <li>Also added a locked field in the proto message. When storing, the field will be set according
086 * to the return value of {@link #hasLock()}. And when loading, there is a new field in Procedure
087 * called {@link #lockedWhenLoading}. We will set it to {@code true} if the locked field in proto
088 * message is {@code true}.</li>
089 * <li>The reason why we can not set the {@link #locked} field directly to {@code true} by calling
090 * {@link #doAcquireLock(Object, ProcedureStore)} is that, during initialization, most procedures
091 * need to wait until master is initialized. So the solution here is that, we introduced a new
092 * method called {@link #waitInitialized(Object)} in Procedure, and move the wait master initialized
093 * related code from {@link #acquireLock(Object)} to this method. And we added a restoreLock method
094 * to Procedure, if {@link #lockedWhenLoading} is {@code true}, we will call the
095 * {@link #acquireLock(Object)} to get the lock, but do not set {@link #locked} to true. And later
096 * when we call {@link #doAcquireLock(Object, ProcedureStore)} and pass the
097 * {@link #waitInitialized(Object)} check, we will test {@link #lockedWhenLoading}, if it is
098 * {@code true}, when we just set the {@link #locked} field to true and return, without actually
099 * calling the {@link #acquireLock(Object)} method since we have already called it once.</li>
100 * </ul>
101 * <p/>
102 * Procedures can be suspended or put in wait state with a callback that gets executed on
103 * Procedure-specified timeout. See {@link #setTimeout(int)}}, and
104 * {@link #setTimeoutFailure(Object)}. See TestProcedureEvents and the TestTimeoutEventProcedure
105 * class for an example usage.
106 * </p>
107 * <p/>
108 * There are hooks for collecting metrics on submit of the procedure and on finish. See
109 * {@link #updateMetricsOnSubmit(Object)} and {@link #updateMetricsOnFinish(Object, long, boolean)}.
110 */
111@InterfaceAudience.Private
112public abstract class Procedure<TEnvironment> implements Comparable<Procedure<TEnvironment>> {
113  private static final Logger LOG = LoggerFactory.getLogger(Procedure.class);
114  public static final long NO_PROC_ID = -1;
115  protected static final int NO_TIMEOUT = -1;
116
117  public enum LockState {
118    LOCK_ACQUIRED, // Lock acquired and ready to execute
119    LOCK_YIELD_WAIT, // Lock not acquired, framework needs to yield
120    LOCK_EVENT_WAIT, // Lock not acquired, an event will yield the procedure
121  }
122
123  // Unchanged after initialization
124  private NonceKey nonceKey = null;
125  private String owner = null;
126  private long parentProcId = NO_PROC_ID;
127  private long rootProcId = NO_PROC_ID;
128  private long procId = NO_PROC_ID;
129  private long submittedTime;
130
131  // Runtime state, updated every operation
132  private ProcedureState state = ProcedureState.INITIALIZING;
133  private RemoteProcedureException exception = null;
134  private int[] stackIndexes = null;
135  private int childrenLatch = 0;
136  // since we do not always maintain stackIndexes if the root procedure does not support rollback,
137  // we need a separated flag to indicate whether a procedure was executed
138  private boolean wasExecuted;
139
140  private volatile int timeout = NO_TIMEOUT;
141  private volatile long lastUpdate;
142
143  private volatile byte[] result = null;
144
145  private volatile boolean locked = false;
146
147  private boolean lockedWhenLoading = false;
148
149  /**
150   * Used for override complete of the procedure without actually doing any logic in the procedure.
151   * If bypass is set to true, when executing it will return null when {@link #doExecute(Object)} is
152   * called to finish the procedure and release any locks it may currently hold. The bypass does
153   * cleanup around the Procedure as far as the Procedure framework is concerned. It does not clean
154   * any internal state that the Procedure's themselves may have set. That is for the Procedures to
155   * do themselves when bypass is called. They should override bypass and do their cleanup in the
156   * overridden bypass method (be sure to call the parent bypass to ensure proper processing).
157   * <p>
158   * </p>
159   * Bypassing a procedure is not like aborting. Aborting a procedure will trigger a rollback. And
160   * since the {@link #abort(Object)} method is overrideable Some procedures may have chosen to
161   * ignore the aborting.
162   */
163  private volatile boolean bypass = false;
164
165  /**
166   * Indicate whether we need to persist the procedure to ProcedureStore after execution. Default to
167   * true, and the implementation can all {@link #skipPersistence()} to let the framework skip the
168   * persistence of the procedure.
169   * <p/>
170   * This is useful when the procedure is in error and you want to retry later. The retry interval
171   * and the number of retries are usually not critical so skip the persistence can save some
172   * resources, and also speed up the restart processing.
173   * <p/>
174   * Notice that this value will be reset to true every time before execution. And when rolling back
175   * we do not test this value.
176   */
177  private boolean persist = true;
178
179  public boolean isBypass() {
180    return bypass;
181  }
182
183  /**
184   * Set the bypass to true. Only called in
185   * {@link ProcedureExecutor#bypassProcedure(long, long, boolean, boolean)} for now. DO NOT use
186   * this method alone, since we can't just bypass one single procedure. We need to bypass its
187   * ancestor too. If your Procedure has set state, it needs to undo it in here.
188   * @param env Current environment. May be null because of context; e.g. pretty-printing procedure
189   *            WALs where there is no 'environment' (and where Procedures that require an
190   *            'environment' won't be run.
191   */
192  protected void bypass(TEnvironment env) {
193    this.bypass = true;
194  }
195
196  boolean needPersistence() {
197    return persist;
198  }
199
200  void resetPersistence() {
201    persist = true;
202  }
203
204  protected final void skipPersistence() {
205    persist = false;
206  }
207
208  /**
209   * The main code of the procedure. It must be idempotent since execute() may be called multiple
210   * times in case of machine failure in the middle of the execution.
211   * @param env the environment passed to the ProcedureExecutor
212   * @return a set of sub-procedures to run or ourselves if there is more work to do or null if the
213   *         procedure is done.
214   * @throws ProcedureYieldException     the procedure will be added back to the queue and retried
215   *                                     later.
216   * @throws InterruptedException        the procedure will be added back to the queue and retried
217   *                                     later.
218   * @throws ProcedureSuspendedException Signal to the executor that Procedure has suspended itself
219   *                                     and has set itself up waiting for an external event to wake
220   *                                     it back up again.
221   */
222  protected abstract Procedure<TEnvironment>[] execute(TEnvironment env)
223    throws ProcedureYieldException, ProcedureSuspendedException, InterruptedException;
224
225  /**
226   * The code to undo what was done by the execute() code. It is called when the procedure or one of
227   * the sub-procedures failed or an abort was requested. It should cleanup all the resources
228   * created by the execute() call. The implementation must be idempotent since rollback() may be
229   * called multiple time in case of machine failure in the middle of the execution.
230   * @param env the environment passed to the ProcedureExecutor
231   * @throws IOException          temporary failure, the rollback will retry later
232   * @throws InterruptedException the procedure will be added back to the queue and retried later
233   */
234  protected abstract void rollback(TEnvironment env) throws IOException, InterruptedException;
235
236  /**
237   * The abort() call is asynchronous and each procedure must decide how to deal with it, if they
238   * want to be abortable. The simplest implementation is to have an AtomicBoolean set in the
239   * abort() method and then the execute() will check if the abort flag is set or not. abort() may
240   * be called multiple times from the client, so the implementation must be idempotent.
241   * <p>
242   * NOTE: abort() is not like Thread.interrupt(). It is just a notification that allows the
243   * procedure implementor abort.
244   */
245  protected abstract boolean abort(TEnvironment env);
246
247  /**
248   * The user-level code of the procedure may have some state to persist (e.g. input arguments or
249   * current position in the processing state) to be able to resume on failure.
250   * @param serializer stores the serializable state
251   */
252  protected abstract void serializeStateData(ProcedureStateSerializer serializer)
253    throws IOException;
254
255  /**
256   * Called on store load to allow the user to decode the previously serialized state.
257   * @param serializer contains the serialized state
258   */
259  protected abstract void deserializeStateData(ProcedureStateSerializer serializer)
260    throws IOException;
261
262  /**
263   * The {@link #doAcquireLock(Object, ProcedureStore)} will be split into two steps, first, it will
264   * call us to determine whether we need to wait for initialization, second, it will call
265   * {@link #acquireLock(Object)} to actually handle the lock for this procedure.
266   * <p/>
267   * This is because that when master restarts, we need to restore the lock state for all the
268   * procedures to not break the semantic if {@link #holdLock(Object)} is true. But the
269   * {@link ProcedureExecutor} will be started before the master finish initialization(as it is part
270   * of the initialization!), so we need to split the code into two steps, and when restore, we just
271   * restore the lock part and ignore the waitInitialized part. Otherwise there will be dead lock.
272   * @return true means we need to wait until the environment has been initialized, otherwise true.
273   */
274  protected boolean waitInitialized(TEnvironment env) {
275    return false;
276  }
277
278  /**
279   * The user should override this method if they need a lock on an Entity. A lock can be anything,
280   * and it is up to the implementor. The Procedure Framework will call this method just before it
281   * invokes {@link #execute(Object)}. It calls {@link #releaseLock(Object)} after the call to
282   * execute.
283   * <p/>
284   * If you need to hold the lock for the life of the Procedure -- i.e. you do not want any other
285   * Procedure interfering while this Procedure is running, see {@link #holdLock(Object)}.
286   * <p/>
287   * Example: in our Master we can execute request in parallel for different tables. We can create
288   * t1 and create t2 and these creates can be executed at the same time. Anything else on t1/t2 is
289   * queued waiting that specific table create to happen.
290   * <p/>
291   * There are 3 LockState:
292   * <ul>
293   * <li>LOCK_ACQUIRED should be returned when the proc has the lock and the proc is ready to
294   * execute.</li>
295   * <li>LOCK_YIELD_WAIT should be returned when the proc has not the lock and the framework should
296   * take care of readding the procedure back to the runnable set for retry</li>
297   * <li>LOCK_EVENT_WAIT should be returned when the proc has not the lock and someone will take
298   * care of readding the procedure back to the runnable set when the lock is available.</li>
299   * </ul>
300   * @return the lock state as described above.
301   */
302  protected LockState acquireLock(TEnvironment env) {
303    return LockState.LOCK_ACQUIRED;
304  }
305
306  /**
307   * The user should override this method, and release lock if necessary.
308   */
309  protected void releaseLock(TEnvironment env) {
310    // no-op
311  }
312
313  /**
314   * Used to keep the procedure lock even when the procedure is yielding or suspended.
315   * @return true if the procedure should hold on the lock until completionCleanup()
316   */
317  protected boolean holdLock(TEnvironment env) {
318    return false;
319  }
320
321  /**
322   * This is used in conjunction with {@link #holdLock(Object)}. If {@link #holdLock(Object)}
323   * returns true, the procedure executor will call acquireLock() once and thereafter not call
324   * {@link #releaseLock(Object)} until the Procedure is done (Normally, it calls release/acquire
325   * around each invocation of {@link #execute(Object)}.
326   * @see #holdLock(Object)
327   * @return true if the procedure has the lock, false otherwise.
328   */
329  public final boolean hasLock() {
330    return locked;
331  }
332
333  /**
334   * Called when the procedure is loaded for replay. The procedure implementor may use this method
335   * to perform some quick operation before replay. e.g. failing the procedure if the state on
336   * replay may be unknown.
337   */
338  protected void beforeReplay(TEnvironment env) {
339    // no-op
340  }
341
342  /**
343   * Called when the procedure is ready to be added to the queue after the loading/replay operation.
344   */
345  protected void afterReplay(TEnvironment env) {
346    // no-op
347  }
348
349  /**
350   * Called when the procedure is marked as completed (success or rollback). The procedure
351   * implementor may use this method to cleanup in-memory states. This operation will not be retried
352   * on failure. If a procedure took a lock, it will have been released when this method runs.
353   */
354  protected void completionCleanup(TEnvironment env) {
355    // no-op
356  }
357
358  /**
359   * By default, the procedure framework/executor will try to run procedures start to finish. Return
360   * true to make the executor yield between each execution step to give other procedures a chance
361   * to run.
362   * @param env the environment passed to the ProcedureExecutor
363   * @return Return true if the executor should yield on completion of an execution step. Defaults
364   *         to return false.
365   */
366  protected boolean isYieldAfterExecutionStep(TEnvironment env) {
367    return false;
368  }
369
370  /**
371   * By default, the executor will keep the procedure result around util the eviction TTL is
372   * expired. The client can cut down the waiting time by requesting that the result is removed from
373   * the executor. In case of system started procedure, we can force the executor to auto-ack.
374   * @param env the environment passed to the ProcedureExecutor
375   * @return true if the executor should wait the client ack for the result. Defaults to return
376   *         true.
377   */
378  protected boolean shouldWaitClientAck(TEnvironment env) {
379    return true;
380  }
381
382  /**
383   * Override this method to provide procedure specific counters for submitted count, failed count
384   * and time histogram.
385   * @param env The environment passed to the procedure executor
386   * @return Container object for procedure related metric
387   */
388  protected ProcedureMetrics getProcedureMetrics(TEnvironment env) {
389    return null;
390  }
391
392  /**
393   * This function will be called just when procedure is submitted for execution. Override this
394   * method to update the metrics at the beginning of the procedure. The default implementation
395   * updates submitted counter if {@link #getProcedureMetrics(Object)} returns non-null
396   * {@link ProcedureMetrics}.
397   */
398  protected void updateMetricsOnSubmit(TEnvironment env) {
399    ProcedureMetrics metrics = getProcedureMetrics(env);
400    if (metrics == null) {
401      return;
402    }
403
404    Counter submittedCounter = metrics.getSubmittedCounter();
405    if (submittedCounter != null) {
406      submittedCounter.increment();
407    }
408  }
409
410  /**
411   * This function will be called just after procedure execution is finished. Override this method
412   * to update metrics at the end of the procedure. If {@link #getProcedureMetrics(Object)} returns
413   * non-null {@link ProcedureMetrics}, the default implementation adds runtime of a procedure to a
414   * time histogram for successfully completed procedures. Increments failed counter for failed
415   * procedures.
416   * <p/>
417   * TODO: As any of the sub-procedures on failure rolls back all procedures in the stack, including
418   * successfully finished siblings, this function may get called twice in certain cases for certain
419   * procedures. Explore further if this can be called once.
420   * @param env     The environment passed to the procedure executor
421   * @param runtime Runtime of the procedure in milliseconds
422   * @param success true if procedure is completed successfully
423   */
424  protected void updateMetricsOnFinish(TEnvironment env, long runtime, boolean success) {
425    ProcedureMetrics metrics = getProcedureMetrics(env);
426    if (metrics == null) {
427      return;
428    }
429
430    if (success) {
431      Histogram timeHisto = metrics.getTimeHisto();
432      if (timeHisto != null) {
433        timeHisto.update(runtime);
434      }
435    } else {
436      Counter failedCounter = metrics.getFailedCounter();
437      if (failedCounter != null) {
438        failedCounter.increment();
439      }
440    }
441  }
442
443  @Override
444  public String toString() {
445    // Return the simple String presentation of the procedure.
446    return toStringSimpleSB().toString();
447  }
448
449  /**
450   * Build the StringBuilder for the simple form of procedure string.
451   * @return the StringBuilder
452   */
453  protected StringBuilder toStringSimpleSB() {
454    final StringBuilder sb = new StringBuilder();
455
456    sb.append("pid=");
457    sb.append(getProcId());
458
459    if (hasParent()) {
460      sb.append(", ppid=");
461      sb.append(getParentProcId());
462    }
463
464    /*
465     * TODO Enable later when this is being used. Currently owner not used. if (hasOwner()) {
466     * sb.append(", owner="); sb.append(getOwner()); }
467     */
468
469    sb.append(", state="); // pState for Procedure State as opposed to any other kind.
470    toStringState(sb);
471
472    sb.append(", hasLock=").append(locked);
473
474    if (bypass) {
475      sb.append(", bypass=").append(bypass);
476    }
477
478    if (hasException()) {
479      sb.append(", exception=" + getException());
480    }
481
482    sb.append("; ");
483    toStringClassDetails(sb);
484
485    return sb;
486  }
487
488  /**
489   * Extend the toString() information with more procedure details
490   */
491  public String toStringDetails() {
492    final StringBuilder sb = toStringSimpleSB();
493
494    sb.append(" submittedTime=");
495    sb.append(getSubmittedTime());
496
497    sb.append(", lastUpdate=");
498    sb.append(getLastUpdate());
499
500    final int[] stackIndices = getStackIndexes();
501    if (stackIndices != null) {
502      sb.append("\n");
503      sb.append("stackIndexes=");
504      sb.append(Arrays.toString(stackIndices));
505    }
506
507    return sb.toString();
508  }
509
510  protected String toStringClass() {
511    StringBuilder sb = new StringBuilder();
512    toStringClassDetails(sb);
513    return sb.toString();
514  }
515
516  /**
517   * Called from {@link #toString()} when interpolating {@link Procedure} State. Allows decorating
518   * generic Procedure State with Procedure particulars.
519   * @param builder Append current {@link ProcedureState}
520   */
521  protected void toStringState(StringBuilder builder) {
522    builder.append(getState());
523  }
524
525  /**
526   * Extend the toString() information with the procedure details e.g. className and parameters
527   * @param builder the string builder to use to append the proc specific information
528   */
529  protected void toStringClassDetails(StringBuilder builder) {
530    builder.append(getClass().getName());
531  }
532
533  // ==========================================================================
534  // Those fields are unchanged after initialization.
535  //
536  // Each procedure will get created from the user or during
537  // ProcedureExecutor.start() during the load() phase and then submitted
538  // to the executor. these fields will never be changed after initialization
539  // ==========================================================================
540  public long getProcId() {
541    return procId;
542  }
543
544  public boolean hasParent() {
545    return parentProcId != NO_PROC_ID;
546  }
547
548  public long getParentProcId() {
549    return parentProcId;
550  }
551
552  public long getRootProcId() {
553    return rootProcId;
554  }
555
556  public String getProcName() {
557    return toStringClass();
558  }
559
560  public NonceKey getNonceKey() {
561    return nonceKey;
562  }
563
564  public long getSubmittedTime() {
565    return submittedTime;
566  }
567
568  public String getOwner() {
569    return owner;
570  }
571
572  public boolean hasOwner() {
573    return owner != null;
574  }
575
576  /**
577   * Called by the ProcedureExecutor to assign the ID to the newly created procedure.
578   */
579  protected void setProcId(long procId) {
580    this.procId = procId;
581    this.submittedTime = EnvironmentEdgeManager.currentTime();
582    setState(ProcedureState.RUNNABLE);
583  }
584
585  /**
586   * Called by the ProcedureExecutor to assign the parent to the newly created procedure.
587   */
588  protected void setParentProcId(long parentProcId) {
589    this.parentProcId = parentProcId;
590  }
591
592  protected void setRootProcId(long rootProcId) {
593    this.rootProcId = rootProcId;
594  }
595
596  /**
597   * Called by the ProcedureExecutor to set the value to the newly created procedure.
598   */
599  protected void setNonceKey(NonceKey nonceKey) {
600    this.nonceKey = nonceKey;
601  }
602
603  public void setOwner(String owner) {
604    this.owner = StringUtils.isEmpty(owner) ? null : owner;
605  }
606
607  public void setOwner(User owner) {
608    assert owner != null : "expected owner to be not null";
609    setOwner(owner.getShortName());
610  }
611
612  /**
613   * Called on store load to initialize the Procedure internals after the creation/deserialization.
614   */
615  protected void setSubmittedTime(long submittedTime) {
616    this.submittedTime = submittedTime;
617  }
618
619  // ==========================================================================
620  // runtime state - timeout related
621  // ==========================================================================
622  /**
623   * @param timeout timeout interval in msec
624   */
625  protected void setTimeout(int timeout) {
626    this.timeout = timeout;
627  }
628
629  public boolean hasTimeout() {
630    return timeout != NO_TIMEOUT;
631  }
632
633  /** Returns the timeout in msec */
634  public int getTimeout() {
635    return timeout;
636  }
637
638  /**
639   * Called on store load to initialize the Procedure internals after the creation/deserialization.
640   */
641  protected void setLastUpdate(long lastUpdate) {
642    this.lastUpdate = lastUpdate;
643  }
644
645  /**
646   * Called by ProcedureExecutor after each time a procedure step is executed.
647   */
648  protected void updateTimestamp() {
649    this.lastUpdate = EnvironmentEdgeManager.currentTime();
650  }
651
652  public long getLastUpdate() {
653    return lastUpdate;
654  }
655
656  /**
657   * Timeout of the next timeout. Called by the ProcedureExecutor if the procedure has timeout set
658   * and the procedure is in the waiting queue.
659   * @return the timestamp of the next timeout.
660   */
661  protected long getTimeoutTimestamp() {
662    return getLastUpdate() + getTimeout();
663  }
664
665  // ==========================================================================
666  // runtime state
667  // ==========================================================================
668  /** Returns the time elapsed between the last update and the start time of the procedure. */
669  public long elapsedTime() {
670    return getLastUpdate() - getSubmittedTime();
671  }
672
673  /** Returns the serialized result if any, otherwise null */
674  public byte[] getResult() {
675    return result;
676  }
677
678  /**
679   * The procedure may leave a "result" on completion.
680   * @param result the serialized result that will be passed to the client
681   */
682  protected void setResult(byte[] result) {
683    this.result = result;
684  }
685
686  /**
687   * Will only be called when loading procedures from procedure store, where we need to record
688   * whether the procedure has already held a lock. Later we will call {@link #restoreLock(Object)}
689   * to actually acquire the lock.
690   */
691  final void lockedWhenLoading() {
692    this.lockedWhenLoading = true;
693  }
694
695  /**
696   * Can only be called when restarting, before the procedure actually being executed, as after we
697   * actually call the {@link #doAcquireLock(Object, ProcedureStore)} method, we will reset
698   * {@link #lockedWhenLoading} to false.
699   * <p/>
700   * Now it is only used in the ProcedureScheduler to determine whether we should put a Procedure in
701   * front of a queue.
702   */
703  public boolean isLockedWhenLoading() {
704    return lockedWhenLoading;
705  }
706
707  // ==============================================================================================
708  // Runtime state, updated every operation by the ProcedureExecutor
709  //
710  // There is always 1 thread at the time operating on the state of the procedure.
711  // The ProcedureExecutor may check and set states, or some Procecedure may
712  // update its own state. but no concurrent updates. we use synchronized here
713  // just because the procedure can get scheduled on different executor threads on each step.
714  // ==============================================================================================
715
716  /** Returns true if the procedure is in a RUNNABLE state. */
717  public synchronized boolean isRunnable() {
718    return state == ProcedureState.RUNNABLE;
719  }
720
721  public synchronized boolean isInitializing() {
722    return state == ProcedureState.INITIALIZING;
723  }
724
725  /** Returns true if the procedure has failed. It may or may not have rolled back. */
726  public synchronized boolean isFailed() {
727    return state == ProcedureState.FAILED || state == ProcedureState.ROLLEDBACK;
728  }
729
730  /** Returns true if the procedure is finished successfully. */
731  public synchronized boolean isSuccess() {
732    return state == ProcedureState.SUCCESS && !hasException();
733  }
734
735  /**
736   * @return true if the procedure is finished. The Procedure may be completed successfully or
737   *         rolledback.
738   */
739  public synchronized boolean isFinished() {
740    return isSuccess() || state == ProcedureState.ROLLEDBACK;
741  }
742
743  /** Returns true if the procedure is waiting for a child to finish or for an external event. */
744  public synchronized boolean isWaiting() {
745    switch (state) {
746      case WAITING:
747      case WAITING_TIMEOUT:
748        return true;
749      default:
750        break;
751    }
752    return false;
753  }
754
755  protected synchronized void setState(final ProcedureState state) {
756    this.state = state;
757    updateTimestamp();
758  }
759
760  public synchronized ProcedureState getState() {
761    return state;
762  }
763
764  protected void setFailure(final String source, final Throwable cause) {
765    setFailure(new RemoteProcedureException(source, cause));
766  }
767
768  protected synchronized void setFailure(final RemoteProcedureException exception) {
769    this.exception = exception;
770    if (!isFinished()) {
771      setState(ProcedureState.FAILED);
772    }
773  }
774
775  protected void setAbortFailure(final String source, final String msg) {
776    setFailure(source, new ProcedureAbortedException(msg));
777  }
778
779  /**
780   * Called by the ProcedureExecutor when the timeout set by setTimeout() is expired.
781   * <p/>
782   * Another usage for this method is to implement retrying. A procedure can set the state to
783   * {@code WAITING_TIMEOUT} by calling {@code setState} method, and throw a
784   * {@link ProcedureSuspendedException} to halt the execution of the procedure, and do not forget a
785   * call {@link #setTimeout(int)} method to set the timeout. And you should also override this
786   * method to wake up the procedure, and also return false to tell the ProcedureExecutor that the
787   * timeout event has been handled.
788   * @return true to let the framework handle the timeout as abort, false in case the procedure
789   *         handled the timeout itself.
790   */
791  protected synchronized boolean setTimeoutFailure(TEnvironment env) {
792    if (state == ProcedureState.WAITING_TIMEOUT) {
793      long timeDiff = EnvironmentEdgeManager.currentTime() - lastUpdate;
794      setFailure("ProcedureExecutor",
795        new TimeoutIOException("Operation timed out after " + StringUtils.humanTimeDiff(timeDiff)));
796      return true;
797    }
798    return false;
799  }
800
801  public synchronized boolean hasException() {
802    return exception != null;
803  }
804
805  public synchronized RemoteProcedureException getException() {
806    return exception;
807  }
808
809  /**
810   * Called by the ProcedureExecutor on procedure-load to restore the latch state
811   */
812  protected synchronized void setChildrenLatch(int numChildren) {
813    this.childrenLatch = numChildren;
814    if (LOG.isTraceEnabled()) {
815      LOG.trace("CHILD LATCH INCREMENT SET " + this.childrenLatch, new Throwable(this.toString()));
816    }
817  }
818
819  /**
820   * Called by the ProcedureExecutor on procedure-load to restore the latch state
821   */
822  protected synchronized void incChildrenLatch() {
823    // TODO: can this be inferred from the stack? I think so...
824    this.childrenLatch++;
825    if (LOG.isTraceEnabled()) {
826      LOG.trace("CHILD LATCH INCREMENT " + this.childrenLatch, new Throwable(this.toString()));
827    }
828  }
829
830  /**
831   * Called by the ProcedureExecutor to notify that one of the sub-procedures has completed.
832   */
833  private synchronized boolean childrenCountDown() {
834    assert childrenLatch > 0 : this;
835    boolean b = --childrenLatch == 0;
836    if (LOG.isTraceEnabled()) {
837      LOG.trace("CHILD LATCH DECREMENT " + childrenLatch, new Throwable(this.toString()));
838    }
839    return b;
840  }
841
842  /**
843   * Try to set this procedure into RUNNABLE state. Succeeds if all subprocedures/children are done.
844   * @return True if we were able to move procedure to RUNNABLE state.
845   */
846  synchronized boolean tryRunnable() {
847    // Don't use isWaiting in the below; it returns true for WAITING and WAITING_TIMEOUT
848    if (getState() == ProcedureState.WAITING && childrenCountDown()) {
849      setState(ProcedureState.RUNNABLE);
850      return true;
851    } else {
852      return false;
853    }
854  }
855
856  protected synchronized boolean hasChildren() {
857    return childrenLatch > 0;
858  }
859
860  protected synchronized int getChildrenLatch() {
861    return childrenLatch;
862  }
863
864  /**
865   * Called by the RootProcedureState on procedure execution. Each procedure store its stack-index
866   * positions.
867   */
868  protected synchronized void addStackIndex(final int index) {
869    if (stackIndexes == null) {
870      stackIndexes = new int[] { index };
871    } else {
872      int count = stackIndexes.length;
873      stackIndexes = Arrays.copyOf(stackIndexes, count + 1);
874      stackIndexes[count] = index;
875    }
876    wasExecuted = true;
877  }
878
879  protected synchronized boolean removeStackIndex() {
880    if (stackIndexes != null && stackIndexes.length > 1) {
881      stackIndexes = Arrays.copyOf(stackIndexes, stackIndexes.length - 1);
882      return false;
883    } else {
884      stackIndexes = null;
885      return true;
886    }
887  }
888
889  /**
890   * Called on store load to initialize the Procedure internals after the creation/deserialization.
891   */
892  protected synchronized void setStackIndexes(final List<Integer> stackIndexes) {
893    this.stackIndexes = new int[stackIndexes.size()];
894    for (int i = 0; i < this.stackIndexes.length; ++i) {
895      this.stackIndexes[i] = stackIndexes.get(i);
896    }
897    // for backward compatible, where a procedure is serialized before we added the executed flag,
898    // the flag will be false so we need to set the wasExecuted flag here
899    this.wasExecuted = true;
900  }
901
902  protected synchronized void setExecuted() {
903    this.wasExecuted = true;
904  }
905
906  public synchronized boolean wasExecuted() {
907    return wasExecuted;
908  }
909
910  protected synchronized int[] getStackIndexes() {
911    return stackIndexes;
912  }
913
914  /**
915   * Return whether the procedure supports rollback. If the procedure does not support rollback, we
916   * can skip the rollback state management which could increase the performance. See HBASE-28210
917   * and HBASE-28212.
918   */
919  protected boolean isRollbackSupported() {
920    return true;
921  }
922
923  // ==========================================================================
924  // Internal methods - called by the ProcedureExecutor
925  // ==========================================================================
926
927  /**
928   * Internal method called by the ProcedureExecutor that starts the user-level code execute().
929   * @throws ProcedureSuspendedException This is used when procedure wants to halt processing and
930   *                                     skip out without changing states or releasing any locks
931   *                                     held.
932   */
933  protected Procedure<TEnvironment>[] doExecute(TEnvironment env)
934    throws ProcedureYieldException, ProcedureSuspendedException, InterruptedException {
935    try {
936      updateTimestamp();
937      if (bypass) {
938        LOG.info("{} bypassed, returning null to finish it", this);
939        return null;
940      }
941      return execute(env);
942    } finally {
943      updateTimestamp();
944    }
945  }
946
947  /**
948   * Internal method called by the ProcedureExecutor that starts the user-level code rollback().
949   */
950  protected void doRollback(TEnvironment env) throws IOException, InterruptedException {
951    try {
952      updateTimestamp();
953      if (bypass) {
954        LOG.info("{} bypassed, skipping rollback", this);
955        return;
956      }
957      rollback(env);
958    } finally {
959      updateTimestamp();
960    }
961  }
962
963  final void restoreLock(TEnvironment env) {
964    if (!lockedWhenLoading) {
965      LOG.debug("{} didn't hold the lock before restarting, skip acquiring lock.", this);
966      return;
967    }
968
969    if (isFinished()) {
970      LOG.debug("{} is already finished, skip acquiring lock.", this);
971      return;
972    }
973
974    if (isBypass()) {
975      LOG.debug("{} is already bypassed, skip acquiring lock.", this);
976      return;
977    }
978    // this can happen if the parent stores the sub procedures but before it can
979    // release its lock, the master restarts
980    if (getState() == ProcedureState.WAITING && !holdLock(env)) {
981      LOG.debug("{} is in WAITING STATE, and holdLock=false, skip acquiring lock.", this);
982      lockedWhenLoading = false;
983      return;
984    }
985    LOG.debug("{} held the lock before restarting, call acquireLock to restore it.", this);
986    LockState state = acquireLock(env);
987    assert state == LockState.LOCK_ACQUIRED;
988  }
989
990  /**
991   * Internal method called by the ProcedureExecutor that starts the user-level code acquireLock().
992   */
993  final LockState doAcquireLock(TEnvironment env, ProcedureStore store) {
994    if (waitInitialized(env)) {
995      return LockState.LOCK_EVENT_WAIT;
996    }
997    if (lockedWhenLoading) {
998      // reset it so we will not consider it anymore
999      lockedWhenLoading = false;
1000      locked = true;
1001      // Here we return without persist the locked state, as lockedWhenLoading is true means
1002      // that the locked field of the procedure stored in procedure store is true, so we do not need
1003      // to store it again.
1004      return LockState.LOCK_ACQUIRED;
1005    }
1006    LockState state = acquireLock(env);
1007    if (state == LockState.LOCK_ACQUIRED) {
1008      locked = true;
1009      // persist that we have held the lock. This must be done before we actually execute the
1010      // procedure, otherwise when restarting, we may consider the procedure does not have a lock,
1011      // but it may have already done some changes as we have already executed it, and if another
1012      // procedure gets the lock, then the semantic will be broken if the holdLock is true, as we do
1013      // not expect that another procedure can be executed in the middle.
1014      store.update(this);
1015    }
1016    return state;
1017  }
1018
1019  /**
1020   * Internal method called by the ProcedureExecutor that starts the user-level code releaseLock().
1021   */
1022  final void doReleaseLock(TEnvironment env, ProcedureStore store) {
1023    locked = false;
1024    // persist that we have released the lock. This must be done before we actually release the
1025    // lock. Another procedure may take this lock immediately after we release the lock, and if we
1026    // crash before persist the information that we have already released the lock, then when
1027    // restarting there will be two procedures which both have the lock and cause problems.
1028    if (getState() != ProcedureState.ROLLEDBACK) {
1029      // If the state is ROLLEDBACK, it means that we have already deleted the procedure from
1030      // procedure store, so do not need to log the release operation any more.
1031      store.update(this);
1032    }
1033    releaseLock(env);
1034  }
1035
1036  protected final ProcedureSuspendedException suspend(int timeoutMillis, boolean jitter)
1037    throws ProcedureSuspendedException {
1038    if (jitter) {
1039      // 10% possible jitter
1040      double add = (double) timeoutMillis * ThreadLocalRandom.current().nextDouble(0.1);
1041      timeoutMillis += add;
1042    }
1043    setTimeout(timeoutMillis);
1044    setState(ProcedureProtos.ProcedureState.WAITING_TIMEOUT);
1045    skipPersistence();
1046    throw new ProcedureSuspendedException();
1047  }
1048
1049  @Override
1050  public int compareTo(final Procedure<TEnvironment> other) {
1051    return Long.compare(getProcId(), other.getProcId());
1052  }
1053
1054  // ==========================================================================
1055  // misc utils
1056  // ==========================================================================
1057
1058  /**
1059   * Get an hashcode for the specified Procedure ID
1060   * @return the hashcode for the specified procId
1061   */
1062  public static long getProcIdHashCode(long procId) {
1063    long h = procId;
1064    h ^= h >> 16;
1065    h *= 0x85ebca6b;
1066    h ^= h >> 13;
1067    h *= 0xc2b2ae35;
1068    h ^= h >> 16;
1069    return h;
1070  }
1071
1072  /**
1073   * Helper to lookup the root Procedure ID given a specified procedure.
1074   */
1075  protected static <T> Long getRootProcedureId(Map<Long, Procedure<T>> procedures,
1076    Procedure<T> proc) {
1077    while (proc.hasParent()) {
1078      proc = procedures.get(proc.getParentProcId());
1079      if (proc == null) {
1080        return null;
1081      }
1082    }
1083    return proc.getProcId();
1084  }
1085
1086  /**
1087   * @param a the first procedure to be compared.
1088   * @param b the second procedure to be compared.
1089   * @return true if the two procedures have the same parent
1090   */
1091  public static boolean haveSameParent(Procedure<?> a, Procedure<?> b) {
1092    return a.hasParent() && b.hasParent() && (a.getParentProcId() == b.getParentProcId());
1093  }
1094}