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.client;
019
020import static java.util.stream.Collectors.toList;
021import static org.apache.hadoop.hbase.client.ConnectionUtils.allOf;
022import static org.apache.hadoop.hbase.client.ConnectionUtils.toCheckExistenceOnly;
023
024import java.util.List;
025import java.util.concurrent.CompletableFuture;
026import java.util.concurrent.TimeUnit;
027import java.util.function.Function;
028import org.apache.hadoop.conf.Configuration;
029import org.apache.hadoop.hbase.CompareOperator;
030import org.apache.hadoop.hbase.TableName;
031import org.apache.hadoop.hbase.filter.Filter;
032import org.apache.hadoop.hbase.io.TimeRange;
033import org.apache.hadoop.hbase.util.Bytes;
034import org.apache.yetus.audience.InterfaceAudience;
035
036import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
037import org.apache.hbase.thirdparty.com.google.protobuf.RpcChannel;
038
039/**
040 * The interface for asynchronous version of Table. Obtain an instance from a
041 * {@link AsyncConnection}.
042 * <p>
043 * The implementation is required to be thread safe.
044 * <p>
045 * Usually the implementation will not throw any exception directly. You need to get the exception
046 * from the returned {@link CompletableFuture}.
047 * @since 2.0.0
048 */
049@InterfaceAudience.Public
050public interface AsyncTable<C extends ScanResultConsumerBase> {
051
052  /**
053   * Gets the fully qualified table name instance of this table.
054   */
055  TableName getName();
056
057  /**
058   * Returns the {@link org.apache.hadoop.conf.Configuration} object used by this instance.
059   * <p>
060   * The reference returned is not a copy, so any change made to it will affect this instance.
061   */
062  Configuration getConfiguration();
063
064  /**
065   * Gets the {@link TableDescriptor} for this table.
066   */
067  CompletableFuture<TableDescriptor> getDescriptor();
068
069  /**
070   * Gets the {@link AsyncTableRegionLocator} for this table.
071   */
072  AsyncTableRegionLocator getRegionLocator();
073  /**
074   * Get timeout of each rpc request in this Table instance. It will be overridden by a more
075   * specific rpc timeout config such as readRpcTimeout or writeRpcTimeout.
076   * @see #getReadRpcTimeout(TimeUnit)
077   * @see #getWriteRpcTimeout(TimeUnit)
078   * @param unit the unit of time the timeout to be represented in
079   * @return rpc timeout in the specified time unit
080   */
081  long getRpcTimeout(TimeUnit unit);
082
083  /**
084   * Get timeout of each rpc read request in this Table instance.
085   * @param unit the unit of time the timeout to be represented in
086   * @return read rpc timeout in the specified time unit
087   */
088  long getReadRpcTimeout(TimeUnit unit);
089
090  /**
091   * Get timeout of each rpc write request in this Table instance.
092   * @param unit the unit of time the timeout to be represented in
093   * @return write rpc timeout in the specified time unit
094   */
095  long getWriteRpcTimeout(TimeUnit unit);
096
097  /**
098   * Get timeout of each operation in Table instance.
099   * @param unit the unit of time the timeout to be represented in
100   * @return operation rpc timeout in the specified time unit
101   */
102  long getOperationTimeout(TimeUnit unit);
103
104  /**
105   * Get the timeout of a single operation in a scan. It works like operation timeout for other
106   * operations.
107   * @param unit the unit of time the timeout to be represented in
108   * @return scan rpc timeout in the specified time unit
109   */
110  long getScanTimeout(TimeUnit unit);
111
112  /**
113   * Test for the existence of columns in the table, as specified by the Get.
114   * <p>
115   * This will return true if the Get matches one or more keys, false if not.
116   * <p>
117   * This is a server-side call so it prevents any data from being transfered to the client.
118   * @return true if the specified Get matches one or more keys, false if not. The return value will
119   *         be wrapped by a {@link CompletableFuture}.
120   */
121  default CompletableFuture<Boolean> exists(Get get) {
122    return get(toCheckExistenceOnly(get)).thenApply(r -> r.getExists());
123  }
124
125  /**
126   * Extracts certain cells from a given row.
127   * @param get The object that specifies what data to fetch and from which row.
128   * @return The data coming from the specified row, if it exists. If the row specified doesn't
129   *         exist, the {@link Result} instance returned won't contain any
130   *         {@link org.apache.hadoop.hbase.KeyValue}, as indicated by {@link Result#isEmpty()}. The
131   *         return value will be wrapped by a {@link CompletableFuture}.
132   */
133  CompletableFuture<Result> get(Get get);
134
135  /**
136   * Puts some data to the table.
137   * @param put The data to put.
138   * @return A {@link CompletableFuture} that always returns null when complete normally.
139   */
140  CompletableFuture<Void> put(Put put);
141
142  /**
143   * Deletes the specified cells/row.
144   * @param delete The object that specifies what to delete.
145   * @return A {@link CompletableFuture} that always returns null when complete normally.
146   */
147  CompletableFuture<Void> delete(Delete delete);
148
149  /**
150   * Appends values to one or more columns within a single row.
151   * <p>
152   * This operation does not appear atomic to readers. Appends are done under a single row lock, so
153   * write operations to a row are synchronized, but readers do not take row locks so get and scan
154   * operations can see this operation partially completed.
155   * @param append object that specifies the columns and amounts to be used for the increment
156   *          operations
157   * @return values of columns after the append operation (maybe null). The return value will be
158   *         wrapped by a {@link CompletableFuture}.
159   */
160  CompletableFuture<Result> append(Append append);
161
162  /**
163   * Increments one or more columns within a single row.
164   * <p>
165   * This operation does not appear atomic to readers. Increments are done under a single row lock,
166   * so write operations to a row are synchronized, but readers do not take row locks so get and
167   * scan operations can see this operation partially completed.
168   * @param increment object that specifies the columns and amounts to be used for the increment
169   *          operations
170   * @return values of columns after the increment. The return value will be wrapped by a
171   *         {@link CompletableFuture}.
172   */
173  CompletableFuture<Result> increment(Increment increment);
174
175  /**
176   * See {@link #incrementColumnValue(byte[], byte[], byte[], long, Durability)}
177   * <p>
178   * The {@link Durability} is defaulted to {@link Durability#SYNC_WAL}.
179   * @param row The row that contains the cell to increment.
180   * @param family The column family of the cell to increment.
181   * @param qualifier The column qualifier of the cell to increment.
182   * @param amount The amount to increment the cell with (or decrement, if the amount is negative).
183   * @return The new value, post increment. The return value will be wrapped by a
184   *         {@link CompletableFuture}.
185   */
186  default CompletableFuture<Long> incrementColumnValue(byte[] row, byte[] family, byte[] qualifier,
187      long amount) {
188    return incrementColumnValue(row, family, qualifier, amount, Durability.SYNC_WAL);
189  }
190
191  /**
192   * Atomically increments a column value. If the column value already exists and is not a
193   * big-endian long, this could throw an exception. If the column value does not yet exist it is
194   * initialized to <code>amount</code> and written to the specified column.
195   * <p>
196   * Setting durability to {@link Durability#SKIP_WAL} means that in a fail scenario you will lose
197   * any increments that have not been flushed.
198   * @param row The row that contains the cell to increment.
199   * @param family The column family of the cell to increment.
200   * @param qualifier The column qualifier of the cell to increment.
201   * @param amount The amount to increment the cell with (or decrement, if the amount is negative).
202   * @param durability The persistence guarantee for this increment.
203   * @return The new value, post increment. The return value will be wrapped by a
204   *         {@link CompletableFuture}.
205   */
206  default CompletableFuture<Long> incrementColumnValue(byte[] row, byte[] family, byte[] qualifier,
207      long amount, Durability durability) {
208    Preconditions.checkNotNull(row, "row is null");
209    Preconditions.checkNotNull(family, "family is null");
210    return increment(
211      new Increment(row).addColumn(family, qualifier, amount).setDurability(durability))
212          .thenApply(r -> Bytes.toLong(r.getValue(family, qualifier)));
213  }
214
215  /**
216   * Atomically checks if a row/family/qualifier value matches the expected value. If it does, it
217   * adds the Put/Delete/RowMutations.
218   * <p>
219   * Use the returned {@link CheckAndMutateBuilder} to construct your request and then execute it.
220   * This is a fluent style API, the code is like:
221   *
222   * <pre>
223   * <code>
224   * table.checkAndMutate(row, family).qualifier(qualifier).ifNotExists().thenPut(put)
225   *     .thenAccept(succ -> {
226   *       if (succ) {
227   *         System.out.println("Check and put succeeded");
228   *       } else {
229   *         System.out.println("Check and put failed");
230   *       }
231   *     });
232   * </code>
233   * </pre>
234   *
235   * @deprecated Since 3.0.0, will be removed in 4.0.0. For internal test use only, do not use it
236   *   any more.
237   */
238  @Deprecated
239  CheckAndMutateBuilder checkAndMutate(byte[] row, byte[] family);
240
241  /**
242   * A helper class for sending checkAndMutate request.
243   *
244   * @deprecated Since 3.0.0, will be removed in 4.0.0. For internal test use only, do not use it
245   *   any more.
246   */
247  @Deprecated
248  interface CheckAndMutateBuilder {
249
250    /**
251     * @param qualifier column qualifier to check.
252     */
253    CheckAndMutateBuilder qualifier(byte[] qualifier);
254
255    /**
256     * @param timeRange time range to check.
257     */
258    CheckAndMutateBuilder timeRange(TimeRange timeRange);
259
260    /**
261     * Check for lack of column.
262     */
263    CheckAndMutateBuilder ifNotExists();
264
265    /**
266     * Check for equality.
267     * @param value the expected value
268     */
269    default CheckAndMutateBuilder ifEquals(byte[] value) {
270      return ifMatches(CompareOperator.EQUAL, value);
271    }
272
273    /**
274     * @param compareOp comparison operator to use
275     * @param value the expected value
276     */
277    CheckAndMutateBuilder ifMatches(CompareOperator compareOp, byte[] value);
278
279    /**
280     * @param put data to put if check succeeds
281     * @return {@code true} if the new put was executed, {@code false} otherwise. The return value
282     *         will be wrapped by a {@link CompletableFuture}.
283     */
284    CompletableFuture<Boolean> thenPut(Put put);
285
286    /**
287     * @param delete data to delete if check succeeds
288     * @return {@code true} if the new delete was executed, {@code false} otherwise. The return
289     *         value will be wrapped by a {@link CompletableFuture}.
290     */
291    CompletableFuture<Boolean> thenDelete(Delete delete);
292
293    /**
294     * @param mutation mutations to perform if check succeeds
295     * @return true if the new mutation was executed, false otherwise. The return value will be
296     *         wrapped by a {@link CompletableFuture}.
297     */
298    CompletableFuture<Boolean> thenMutate(RowMutations mutation);
299  }
300
301  /**
302   * Atomically checks if a row matches the specified filter. If it does, it adds the
303   * Put/Delete/RowMutations.
304   * <p>
305   * Use the returned {@link CheckAndMutateWithFilterBuilder} to construct your request and then
306   * execute it. This is a fluent style API, the code is like:
307   *
308   * <pre>
309   * <code>
310   * table.checkAndMutate(row, filter).thenPut(put)
311   *     .thenAccept(succ -> {
312   *       if (succ) {
313   *         System.out.println("Check and put succeeded");
314   *       } else {
315   *         System.out.println("Check and put failed");
316   *       }
317   *     });
318   * </code>
319   * </pre>
320   *
321   * @deprecated Since 3.0.0, will be removed in 4.0.0. For internal test use only, do not use it
322   *   any more.
323   */
324  @Deprecated
325  CheckAndMutateWithFilterBuilder checkAndMutate(byte[] row, Filter filter);
326
327  /**
328   * A helper class for sending checkAndMutate request with a filter.
329   *
330   * @deprecated Since 3.0.0, will be removed in 4.0.0. For internal test use only, do not use it
331   *   any more.
332   */
333  @Deprecated
334  interface CheckAndMutateWithFilterBuilder {
335
336    /**
337     * @param timeRange time range to check.
338     */
339    CheckAndMutateWithFilterBuilder timeRange(TimeRange timeRange);
340
341    /**
342     * @param put data to put if check succeeds
343     * @return {@code true} if the new put was executed, {@code false} otherwise. The return value
344     *         will be wrapped by a {@link CompletableFuture}.
345     */
346    CompletableFuture<Boolean> thenPut(Put put);
347
348    /**
349     * @param delete data to delete if check succeeds
350     * @return {@code true} if the new delete was executed, {@code false} otherwise. The return
351     *         value will be wrapped by a {@link CompletableFuture}.
352     */
353    CompletableFuture<Boolean> thenDelete(Delete delete);
354
355    /**
356     * @param mutation mutations to perform if check succeeds
357     * @return true if the new mutation was executed, false otherwise. The return value will be
358     *         wrapped by a {@link CompletableFuture}.
359     */
360    CompletableFuture<Boolean> thenMutate(RowMutations mutation);
361  }
362
363  /**
364   * checkAndMutate that atomically checks if a row matches the specified condition. If it does,
365   * it performs the specified action.
366   *
367   * @param checkAndMutate The CheckAndMutate object.
368   * @return A {@link CompletableFuture}s that represent the result for the CheckAndMutate.
369   */
370  CompletableFuture<CheckAndMutateResult> checkAndMutate(CheckAndMutate checkAndMutate);
371
372  /**
373   * Batch version of checkAndMutate. The specified CheckAndMutates are batched only in the sense
374   * that they are sent to a RS in one RPC, but each CheckAndMutate operation is still executed
375   * atomically (and thus, each may fail independently of others).
376   *
377   * @param checkAndMutates The list of CheckAndMutate.
378   * @return A list of {@link CompletableFuture}s that represent the result for each
379   *   CheckAndMutate.
380   */
381  List<CompletableFuture<CheckAndMutateResult>> checkAndMutate(
382    List<CheckAndMutate> checkAndMutates);
383
384  /**
385   * A simple version of batch checkAndMutate. It will fail if there are any failures.
386   *
387   * @param checkAndMutates The list of rows to apply.
388   * @return A {@link CompletableFuture} that wrapper the result list.
389   */
390  default CompletableFuture<List<CheckAndMutateResult>> checkAndMutateAll(
391    List<CheckAndMutate> checkAndMutates) {
392    return allOf(checkAndMutate(checkAndMutates));
393  }
394
395  /**
396   * Performs multiple mutations atomically on a single row. Currently {@link Put} and
397   * {@link Delete} are supported.
398   * @param mutation object that specifies the set of mutations to perform atomically
399   * @return A {@link CompletableFuture} that always returns null when complete normally.
400   */
401  CompletableFuture<Void> mutateRow(RowMutations mutation);
402
403  /**
404   * The scan API uses the observer pattern.
405   * @param scan A configured {@link Scan} object.
406   * @param consumer the consumer used to receive results.
407   * @see ScanResultConsumer
408   * @see AdvancedScanResultConsumer
409   */
410  void scan(Scan scan, C consumer);
411
412  /**
413   * Gets a scanner on the current table for the given family.
414   * @param family The column family to scan.
415   * @return A scanner.
416   */
417  default ResultScanner getScanner(byte[] family) {
418    return getScanner(new Scan().addFamily(family));
419  }
420
421  /**
422   * Gets a scanner on the current table for the given family and qualifier.
423   * @param family The column family to scan.
424   * @param qualifier The column qualifier to scan.
425   * @return A scanner.
426   */
427  default ResultScanner getScanner(byte[] family, byte[] qualifier) {
428    return getScanner(new Scan().addColumn(family, qualifier));
429  }
430
431  /**
432   * Returns a scanner on the current table as specified by the {@link Scan} object.
433   * @param scan A configured {@link Scan} object.
434   * @return A scanner.
435   */
436  ResultScanner getScanner(Scan scan);
437
438  /**
439   * Return all the results that match the given scan object.
440   * <p>
441   * Notice that usually you should use this method with a {@link Scan} object that has limit set.
442   * For example, if you want to get the closest row after a given row, you could do this:
443   * <p>
444   *
445   * <pre>
446   * <code>
447   * table.scanAll(new Scan().withStartRow(row, false).setLimit(1)).thenAccept(results -> {
448   *   if (results.isEmpty()) {
449   *      System.out.println("No row after " + Bytes.toStringBinary(row));
450   *   } else {
451   *     System.out.println("The closest row after " + Bytes.toStringBinary(row) + " is "
452   *         + Bytes.toStringBinary(results.stream().findFirst().get().getRow()));
453   *   }
454   * });
455   * </code>
456   * </pre>
457   * <p>
458   * If your result set is very large, you should use other scan method to get a scanner or use
459   * callback to process the results. They will do chunking to prevent OOM. The scanAll method will
460   * fetch all the results and store them in a List and then return the list to you.
461   * <p>
462   * The scan metrics will be collected background if you enable it but you have no way to get it.
463   * Usually you can get scan metrics from {@code ResultScanner}, or through
464   * {@code ScanResultConsumer.onScanMetricsCreated} but this method only returns a list of results.
465   * So if you really care about scan metrics then you'd better use other scan methods which return
466   * a {@code ResultScanner} or let you pass in a {@code ScanResultConsumer}. There is no
467   * performance difference between these scan methods so do not worry.
468   * @param scan A configured {@link Scan} object. So if you use this method to fetch a really large
469   *          result set, it is likely to cause OOM.
470   * @return The results of this small scan operation. The return value will be wrapped by a
471   *         {@link CompletableFuture}.
472   */
473  CompletableFuture<List<Result>> scanAll(Scan scan);
474
475  /**
476   * Test for the existence of columns in the table, as specified by the Gets.
477   * <p>
478   * This will return a list of booleans. Each value will be true if the related Get matches one or
479   * more keys, false if not.
480   * <p>
481   * This is a server-side call so it prevents any data from being transferred to the client.
482   * @param gets the Gets
483   * @return A list of {@link CompletableFuture}s that represent the existence for each get.
484   */
485  default List<CompletableFuture<Boolean>> exists(List<Get> gets) {
486    return get(toCheckExistenceOnly(gets)).stream()
487        .<CompletableFuture<Boolean>> map(f -> f.thenApply(r -> r.getExists())).collect(toList());
488  }
489
490  /**
491   * A simple version for batch exists. It will fail if there are any failures and you will get the
492   * whole result boolean list at once if the operation is succeeded.
493   * @param gets the Gets
494   * @return A {@link CompletableFuture} that wrapper the result boolean list.
495   */
496  default CompletableFuture<List<Boolean>> existsAll(List<Get> gets) {
497    return allOf(exists(gets));
498  }
499
500  /**
501   * Extracts certain cells from the given rows, in batch.
502   * <p>
503   * Notice that you may not get all the results with this function, which means some of the
504   * returned {@link CompletableFuture}s may succeed while some of the other returned
505   * {@link CompletableFuture}s may fail.
506   * @param gets The objects that specify what data to fetch and from which rows.
507   * @return A list of {@link CompletableFuture}s that represent the result for each get.
508   */
509  List<CompletableFuture<Result>> get(List<Get> gets);
510
511  /**
512   * A simple version for batch get. It will fail if there are any failures and you will get the
513   * whole result list at once if the operation is succeeded.
514   * @param gets The objects that specify what data to fetch and from which rows.
515   * @return A {@link CompletableFuture} that wrapper the result list.
516   */
517  default CompletableFuture<List<Result>> getAll(List<Get> gets) {
518    return allOf(get(gets));
519  }
520
521  /**
522   * Puts some data in the table, in batch.
523   * @param puts The list of mutations to apply.
524   * @return A list of {@link CompletableFuture}s that represent the result for each put.
525   */
526  List<CompletableFuture<Void>> put(List<Put> puts);
527
528  /**
529   * A simple version of batch put. It will fail if there are any failures.
530   * @param puts The list of mutations to apply.
531   * @return A {@link CompletableFuture} that always returns null when complete normally.
532   */
533  default CompletableFuture<Void> putAll(List<Put> puts) {
534    return allOf(put(puts)).thenApply(r -> null);
535  }
536
537  /**
538   * Deletes the specified cells/rows in bulk.
539   * @param deletes list of things to delete.
540   * @return A list of {@link CompletableFuture}s that represent the result for each delete.
541   */
542  List<CompletableFuture<Void>> delete(List<Delete> deletes);
543
544  /**
545   * A simple version of batch delete. It will fail if there are any failures.
546   * @param deletes list of things to delete.
547   * @return A {@link CompletableFuture} that always returns null when complete normally.
548   */
549  default CompletableFuture<Void> deleteAll(List<Delete> deletes) {
550    return allOf(delete(deletes)).thenApply(r -> null);
551  }
552
553  /**
554   * Method that does a batch call on Deletes, Gets, Puts, Increments, Appends and RowMutations. The
555   * ordering of execution of the actions is not defined. Meaning if you do a Put and a Get in the
556   * same {@link #batch} call, you will not necessarily be guaranteed that the Get returns what the
557   * Put had put.
558   * @param actions list of Get, Put, Delete, Increment, Append, and RowMutations objects
559   * @return A list of {@link CompletableFuture}s that represent the result for each action.
560   */
561  <T> List<CompletableFuture<T>> batch(List<? extends Row> actions);
562
563  /**
564   * A simple version of batch. It will fail if there are any failures and you will get the whole
565   * result list at once if the operation is succeeded.
566   * @param actions list of Get, Put, Delete, Increment, Append and RowMutations objects
567   * @return A list of the result for the actions. Wrapped by a {@link CompletableFuture}.
568   */
569  default <T> CompletableFuture<List<T>> batchAll(List<? extends Row> actions) {
570    return allOf(batch(actions));
571  }
572
573  /**
574   * Execute the given coprocessor call on the region which contains the given {@code row}.
575   * <p>
576   * The {@code stubMaker} is just a delegation to the {@code newStub} call. Usually it is only a
577   * one line lambda expression, like:
578   *
579   * <pre>
580   * <code>
581   * channel -> xxxService.newStub(channel)
582   * </code>
583   * </pre>
584   *
585   * @param stubMaker a delegation to the actual {@code newStub} call.
586   * @param callable a delegation to the actual protobuf rpc call. See the comment of
587   *          {@link ServiceCaller} for more details.
588   * @param row The row key used to identify the remote region location
589   * @param <S> the type of the asynchronous stub
590   * @param <R> the type of the return value
591   * @return the return value of the protobuf rpc call, wrapped by a {@link CompletableFuture}.
592   * @see ServiceCaller
593   */
594  <S, R> CompletableFuture<R> coprocessorService(Function<RpcChannel, S> stubMaker,
595      ServiceCaller<S, R> callable, byte[] row);
596
597  /**
598   * The callback when we want to execute a coprocessor call on a range of regions.
599   * <p>
600   * As the locating itself also takes some time, the implementation may want to send rpc calls on
601   * the fly, which means we do not know how many regions we have when we get the return value of
602   * the rpc calls, so we need an {@link #onComplete()} which is used to tell you that we have
603   * passed all the return values to you(through the {@link #onRegionComplete(RegionInfo, Object)}
604   * or {@link #onRegionError(RegionInfo, Throwable)} calls), i.e, there will be no
605   * {@link #onRegionComplete(RegionInfo, Object)} or {@link #onRegionError(RegionInfo, Throwable)}
606   * calls in the future.
607   * <p>
608   * Here is a pseudo code to describe a typical implementation of a range coprocessor service
609   * method to help you better understand how the {@link CoprocessorCallback} will be called. The
610   * {@code callback} in the pseudo code is our {@link CoprocessorCallback}. And notice that the
611   * {@code whenComplete} is {@code CompletableFuture.whenComplete}.
612   *
613   * <pre>
614   * locateThenCall(byte[] row) {
615   *   locate(row).whenComplete((location, locateError) -> {
616   *     if (locateError != null) {
617   *       callback.onError(locateError);
618   *       return;
619   *     }
620   *     incPendingCall();
621   *     region = location.getRegion();
622   *     if (region.getEndKey() > endKey) {
623   *       locateEnd = true;
624   *     } else {
625   *       locateThenCall(region.getEndKey());
626   *     }
627   *     sendCall().whenComplete((resp, error) -> {
628   *       if (error != null) {
629   *         callback.onRegionError(region, error);
630   *       } else {
631   *         callback.onRegionComplete(region, resp);
632   *       }
633   *       if (locateEnd && decPendingCallAndGet() == 0) {
634   *         callback.onComplete();
635   *       }
636   *     });
637   *   });
638   * }
639   * </pre>
640   */
641  @InterfaceAudience.Public
642  interface CoprocessorCallback<R> {
643
644    /**
645     * @param region the region that the response belongs to
646     * @param resp the response of the coprocessor call
647     */
648    void onRegionComplete(RegionInfo region, R resp);
649
650    /**
651     * @param region the region that the error belongs to
652     * @param error the response error of the coprocessor call
653     */
654    void onRegionError(RegionInfo region, Throwable error);
655
656    /**
657     * Indicate that all responses of the regions have been notified by calling
658     * {@link #onRegionComplete(RegionInfo, Object)} or
659     * {@link #onRegionError(RegionInfo, Throwable)}.
660     */
661    void onComplete();
662
663    /**
664     * Indicate that we got an error which does not belong to any regions. Usually a locating error.
665     */
666    void onError(Throwable error);
667  }
668
669  /**
670   * Helper class for sending coprocessorService request that executes a coprocessor call on regions
671   * which are covered by a range.
672   * <p>
673   * If {@code fromRow} is not specified the selection will start with the first table region. If
674   * {@code toRow} is not specified the selection will continue through the last table region.
675   * @param <S> the type of the protobuf Service you want to call.
676   * @param <R> the type of the return value.
677   */
678  interface CoprocessorServiceBuilder<S, R> {
679
680    /**
681     * @param startKey start region selection with region containing this row, inclusive.
682     */
683    default CoprocessorServiceBuilder<S, R> fromRow(byte[] startKey) {
684      return fromRow(startKey, true);
685    }
686
687    /**
688     * @param startKey start region selection with region containing this row
689     * @param inclusive whether to include the startKey
690     */
691    CoprocessorServiceBuilder<S, R> fromRow(byte[] startKey, boolean inclusive);
692
693    /**
694     * @param endKey select regions up to and including the region containing this row, exclusive.
695     */
696    default CoprocessorServiceBuilder<S, R> toRow(byte[] endKey) {
697      return toRow(endKey, false);
698    }
699
700    /**
701     * @param endKey select regions up to and including the region containing this row
702     * @param inclusive whether to include the endKey
703     */
704    CoprocessorServiceBuilder<S, R> toRow(byte[] endKey, boolean inclusive);
705
706    /**
707     * Execute the coprocessorService request. You can get the response through the
708     * {@link CoprocessorCallback}.
709     */
710    void execute();
711  }
712
713  /**
714   * Execute a coprocessor call on the regions which are covered by a range.
715   * <p>
716   * Use the returned {@link CoprocessorServiceBuilder} construct your request and then execute it.
717   * <p>
718   * The {@code stubMaker} is just a delegation to the {@code xxxService.newStub} call. Usually it
719   * is only a one line lambda expression, like:
720   *
721   * <pre>
722   * <code>
723   * channel -> xxxService.newStub(channel)
724   * </code>
725   * </pre>
726   *
727   * @param stubMaker a delegation to the actual {@code newStub} call.
728   * @param callable a delegation to the actual protobuf rpc call. See the comment of
729   *          {@link ServiceCaller} for more details.
730   * @param callback callback to get the response. See the comment of {@link CoprocessorCallback}
731   *          for more details.
732   */
733  <S, R> CoprocessorServiceBuilder<S, R> coprocessorService(Function<RpcChannel, S> stubMaker,
734      ServiceCaller<S, R> callable, CoprocessorCallback<R> callback);
735}