https://github.com/datastax/java-driver/java-driver-core: A driver for Apache Cassandra(R) 2.1+ that works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's native protocol versions 3 and above.
  • Various (DataStax) 
/*
 * Copyright DataStax, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.datastax.oss.driver.api.core.retry;

import com.datastax.oss.driver.api.core.ConsistencyLevel;
import com.datastax.oss.driver.api.core.connection.ClosedConnectionException;
import com.datastax.oss.driver.api.core.connection.HeartbeatException;
import com.datastax.oss.driver.api.core.loadbalancing.LoadBalancingPolicy;
import com.datastax.oss.driver.api.core.servererrors.BootstrappingException;
import com.datastax.oss.driver.api.core.servererrors.CoordinatorException;
import com.datastax.oss.driver.api.core.servererrors.FunctionFailureException;
import com.datastax.oss.driver.api.core.servererrors.OverloadedException;
import com.datastax.oss.driver.api.core.servererrors.ProtocolError;
import com.datastax.oss.driver.api.core.servererrors.QueryValidationException;
import com.datastax.oss.driver.api.core.servererrors.ReadFailureException;
import com.datastax.oss.driver.api.core.servererrors.ReadTimeoutException;
import com.datastax.oss.driver.api.core.servererrors.ServerError;
import com.datastax.oss.driver.api.core.servererrors.TruncateException;
import com.datastax.oss.driver.api.core.servererrors.WriteFailureException;
import com.datastax.oss.driver.api.core.servererrors.WriteType;
import com.datastax.oss.driver.api.core.session.Request;
import edu.umd.cs.findbugs.annotations.NonNull;


Defines the behavior to adopt when a request fails.

For each request, the driver gets a "query plan" (a list of coordinators to try) from the LoadBalancingPolicy, and tries each node in sequence. This policy is invoked if the request to that node fails. 
The methods of this interface are invoked on I/O threads, therefore implementations should
never block. In particular, don't call Thread.sleep(long) to retry after a delay: this would prevent asynchronous processing of other requests, and very negatively impact throughput. If the application needs to back off and retry later, this should be implemented in client code, not in this policy. 
/**
 * Defines the behavior to adopt when a request fails.
 *
 * <p>For each request, the driver gets a "query plan" (a list of coordinators to try) from the
 * {@link LoadBalancingPolicy}, and tries each node in sequence. This policy is invoked if the
 * request to that node fails.
 *
 * <p>The methods of this interface are invoked on I/O threads, therefore <b>implementations should
 * never block</b>. In particular, don't call {@link Thread#sleep(long)} to retry after a delay:
 * this would prevent asynchronous processing of other requests, and very negatively impact
 * throughput. If the application needs to back off and retry later, this should be implemented in
 * client code, not in this policy.
 */
public interface RetryPolicy extends AutoCloseable {

  
Whether to retry when the server replied with a READ_TIMEOUT error; this indicates a server-side timeout during a read query, i.e. some replicas did not reply to the
coordinator in time.

Params:
  • request – the request that timed out.
  • cl – the requested consistency level.
  • blockFor – the minimum number of replica acknowledgements/responses that were required to
    fulfill the operation.
  • received – the number of replica that had acknowledged/responded to the operation before
    it failed.
  • dataPresent – whether the actual data was amongst the received replica responses. See ReadTimeoutException.wasDataPresent().
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
Deprecated:As of version 4.10, use onReadTimeoutVerdict(Request, ConsistencyLevel, int, int, boolean, int) instead.
/**
   * Whether to retry when the server replied with a {@code READ_TIMEOUT} error; this indicates a
   * <b>server-side</b> timeout during a read query, i.e. some replicas did not reply to the
   * coordinator in time.
   *
   * @param request the request that timed out.
   * @param cl the requested consistency level.
   * @param blockFor the minimum number of replica acknowledgements/responses that were required to
   *     fulfill the operation.
   * @param received the number of replica that had acknowledged/responded to the operation before
   *     it failed.
   * @param dataPresent whether the actual data was amongst the received replica responses. See
   *     {@link ReadTimeoutException#wasDataPresent()}.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   * @deprecated As of version 4.10, use {@link #onReadTimeoutVerdict(Request, ConsistencyLevel,
   *     int, int, boolean, int)} instead.
   */
  @Deprecated
  RetryDecision onReadTimeout(
      @NonNull Request request,
      @NonNull ConsistencyLevel cl,
      int blockFor,
      int received,
      boolean dataPresent,
      int retryCount);

  
Whether to retry when the server replied with a READ_TIMEOUT error; this indicates a server-side timeout during a read query, i.e. some replicas did not reply to the
coordinator in time.

Params:
  • request – the request that timed out.
  • cl – the requested consistency level.
  • blockFor – the minimum number of replica acknowledgements/responses that were required to
    fulfill the operation.
  • received – the number of replica that had acknowledged/responded to the operation before
    it failed.
  • dataPresent – whether the actual data was amongst the received replica responses. See ReadTimeoutException.wasDataPresent().
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
/**
   * Whether to retry when the server replied with a {@code READ_TIMEOUT} error; this indicates a
   * <b>server-side</b> timeout during a read query, i.e. some replicas did not reply to the
   * coordinator in time.
   *
   * @param request the request that timed out.
   * @param cl the requested consistency level.
   * @param blockFor the minimum number of replica acknowledgements/responses that were required to
   *     fulfill the operation.
   * @param received the number of replica that had acknowledged/responded to the operation before
   *     it failed.
   * @param dataPresent whether the actual data was amongst the received replica responses. See
   *     {@link ReadTimeoutException#wasDataPresent()}.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   */
  default RetryVerdict onReadTimeoutVerdict(
      @NonNull Request request,
      @NonNull ConsistencyLevel cl,
      int blockFor,
      int received,
      boolean dataPresent,
      int retryCount) {
    RetryDecision decision =
        onReadTimeout(request, cl, blockFor, received, dataPresent, retryCount);
    return () -> decision;
  }

  
Whether to retry when the server replied with a WRITE_TIMEOUT error; this indicates a server-side timeout during a write query, i.e. some replicas did not reply to the
coordinator in time.

Note that this method will only be invoked for Request.isIdempotent() idempotent} requests: when a write times out, it is impossible to determine with 100% certainty whether the mutation was applied or not, so the write is never safe to retry; the driver will rethrow the error directly, without invoking the retry policy. 
Params:
  • request – the request that timed out.
  • cl – the requested consistency level.
  • writeType – the type of the write for which the timeout was raised.
  • blockFor – the minimum number of replica acknowledgements/responses that were required to
    fulfill the operation.
  • received – the number of replica that had acknowledged/responded to the operation before
    it failed.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
Deprecated:As of version 4.10, use onWriteTimeoutVerdict(Request, ConsistencyLevel, WriteType, int, int, int) instead.
/**
   * Whether to retry when the server replied with a {@code WRITE_TIMEOUT} error; this indicates a
   * <b>server-side</b> timeout during a write query, i.e. some replicas did not reply to the
   * coordinator in time.
   *
   * <p>Note that this method will only be invoked for {@link Request#isIdempotent()} idempotent}
   * requests: when a write times out, it is impossible to determine with 100% certainty whether the
   * mutation was applied or not, so the write is never safe to retry; the driver will rethrow the
   * error directly, without invoking the retry policy.
   *
   * @param request the request that timed out.
   * @param cl the requested consistency level.
   * @param writeType the type of the write for which the timeout was raised.
   * @param blockFor the minimum number of replica acknowledgements/responses that were required to
   *     fulfill the operation.
   * @param received the number of replica that had acknowledged/responded to the operation before
   *     it failed.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   * @deprecated As of version 4.10, use {@link #onWriteTimeoutVerdict(Request, ConsistencyLevel,
   *     WriteType, int, int, int)} instead.
   */
  @Deprecated
  RetryDecision onWriteTimeout(
      @NonNull Request request,
      @NonNull ConsistencyLevel cl,
      @NonNull WriteType writeType,
      int blockFor,
      int received,
      int retryCount);

  
Whether to retry when the server replied with a WRITE_TIMEOUT error; this indicates a server-side timeout during a write query, i.e. some replicas did not reply to the
coordinator in time.

Note that this method will only be invoked for Request.isIdempotent() idempotent} requests: when a write times out, it is impossible to determine with 100% certainty whether the mutation was applied or not, so the write is never safe to retry; the driver will rethrow the error directly, without invoking the retry policy. 
Params:
  • request – the request that timed out.
  • cl – the requested consistency level.
  • writeType – the type of the write for which the timeout was raised.
  • blockFor – the minimum number of replica acknowledgements/responses that were required to
    fulfill the operation.
  • received – the number of replica that had acknowledged/responded to the operation before
    it failed.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
/**
   * Whether to retry when the server replied with a {@code WRITE_TIMEOUT} error; this indicates a
   * <b>server-side</b> timeout during a write query, i.e. some replicas did not reply to the
   * coordinator in time.
   *
   * <p>Note that this method will only be invoked for {@link Request#isIdempotent()} idempotent}
   * requests: when a write times out, it is impossible to determine with 100% certainty whether the
   * mutation was applied or not, so the write is never safe to retry; the driver will rethrow the
   * error directly, without invoking the retry policy.
   *
   * @param request the request that timed out.
   * @param cl the requested consistency level.
   * @param writeType the type of the write for which the timeout was raised.
   * @param blockFor the minimum number of replica acknowledgements/responses that were required to
   *     fulfill the operation.
   * @param received the number of replica that had acknowledged/responded to the operation before
   *     it failed.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   */
  default RetryVerdict onWriteTimeoutVerdict(
      @NonNull Request request,
      @NonNull ConsistencyLevel cl,
      @NonNull WriteType writeType,
      int blockFor,
      int received,
      int retryCount) {
    RetryDecision decision = onWriteTimeout(request, cl, writeType, blockFor, received, retryCount);
    return () -> decision;
  }

  
Whether to retry when the server replied with an UNAVAILABLE error; this indicates that the coordinator determined that there were not enough replicas alive to perform a query with the requested consistency level. 
Params:
  • request – the request that timed out.
  • cl – the requested consistency level.
  • required – the number of replica acknowledgements/responses required to perform the
    operation (with its required consistency level).
  • alive – the number of replicas that were known to be alive by the coordinator node when it
    tried to execute the operation.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
Deprecated:As of version 4.10, use onUnavailableVerdict(Request, ConsistencyLevel, int, int, int) instead.
/**
   * Whether to retry when the server replied with an {@code UNAVAILABLE} error; this indicates that
   * the coordinator determined that there were not enough replicas alive to perform a query with
   * the requested consistency level.
   *
   * @param request the request that timed out.
   * @param cl the requested consistency level.
   * @param required the number of replica acknowledgements/responses required to perform the
   *     operation (with its required consistency level).
   * @param alive the number of replicas that were known to be alive by the coordinator node when it
   *     tried to execute the operation.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   * @deprecated As of version 4.10, use {@link #onUnavailableVerdict(Request, ConsistencyLevel,
   *     int, int, int)} instead.
   */
  @Deprecated
  RetryDecision onUnavailable(
      @NonNull Request request,
      @NonNull ConsistencyLevel cl,
      int required,
      int alive,
      int retryCount);

  
Whether to retry when the server replied with an UNAVAILABLE error; this indicates that the coordinator determined that there were not enough replicas alive to perform a query with the requested consistency level. 
Params:
  • request – the request that timed out.
  • cl – the requested consistency level.
  • required – the number of replica acknowledgements/responses required to perform the
    operation (with its required consistency level).
  • alive – the number of replicas that were known to be alive by the coordinator node when it
    tried to execute the operation.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
/**
   * Whether to retry when the server replied with an {@code UNAVAILABLE} error; this indicates that
   * the coordinator determined that there were not enough replicas alive to perform a query with
   * the requested consistency level.
   *
   * @param request the request that timed out.
   * @param cl the requested consistency level.
   * @param required the number of replica acknowledgements/responses required to perform the
   *     operation (with its required consistency level).
   * @param alive the number of replicas that were known to be alive by the coordinator node when it
   *     tried to execute the operation.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   */
  default RetryVerdict onUnavailableVerdict(
      @NonNull Request request,
      @NonNull ConsistencyLevel cl,
      int required,
      int alive,
      int retryCount) {
    RetryDecision decision = onUnavailable(request, cl, required, alive, retryCount);
    return () -> decision;
  }

  
Whether to retry when a request was aborted before we could get a response from the server.

This can happen in two cases: if the connection was closed due to an external event (this will manifest as a ClosedConnectionException, or HeartbeatException for a heartbeat failure); or if there was an unexpected error while decoding the response (this can only be a driver bug). 
Note that this method will only be invoked for 
idempotent requests: when execution was aborted before getting a response, it is impossible to determine with 100% certainty whether a mutation was applied or not, so a write is never safe to retry; the driver will rethrow the error directly, without invoking the retry policy. 
Params:
  • request – the request that was aborted.
  • error – the error.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
Deprecated:As of version 4.10, use onRequestAbortedVerdict(Request, Throwable, int) instead.
/**
   * Whether to retry when a request was aborted before we could get a response from the server.
   *
   * <p>This can happen in two cases: if the connection was closed due to an external event (this
   * will manifest as a {@link ClosedConnectionException}, or {@link HeartbeatException} for a
   * heartbeat failure); or if there was an unexpected error while decoding the response (this can
   * only be a driver bug).
   *
   * <p>Note that this method will only be invoked for {@linkplain Request#isIdempotent()
   * idempotent} requests: when execution was aborted before getting a response, it is impossible to
   * determine with 100% certainty whether a mutation was applied or not, so a write is never safe
   * to retry; the driver will rethrow the error directly, without invoking the retry policy.
   *
   * @param request the request that was aborted.
   * @param error the error.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   * @deprecated As of version 4.10, use {@link #onRequestAbortedVerdict(Request, Throwable, int)}
   *     instead.
   */
  @Deprecated
  RetryDecision onRequestAborted(
      @NonNull Request request, @NonNull Throwable error, int retryCount);

  
Whether to retry when a request was aborted before we could get a response from the server.

This can happen in two cases: if the connection was closed due to an external event (this will manifest as a ClosedConnectionException, or HeartbeatException for a heartbeat failure); or if there was an unexpected error while decoding the response (this can only be a driver bug). 
Note that this method will only be invoked for 
idempotent requests: when execution was aborted before getting a response, it is impossible to determine with 100% certainty whether a mutation was applied or not, so a write is never safe to retry; the driver will rethrow the error directly, without invoking the retry policy. 
Params:
  • request – the request that was aborted.
  • error – the error.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
/**
   * Whether to retry when a request was aborted before we could get a response from the server.
   *
   * <p>This can happen in two cases: if the connection was closed due to an external event (this
   * will manifest as a {@link ClosedConnectionException}, or {@link HeartbeatException} for a
   * heartbeat failure); or if there was an unexpected error while decoding the response (this can
   * only be a driver bug).
   *
   * <p>Note that this method will only be invoked for {@linkplain Request#isIdempotent()
   * idempotent} requests: when execution was aborted before getting a response, it is impossible to
   * determine with 100% certainty whether a mutation was applied or not, so a write is never safe
   * to retry; the driver will rethrow the error directly, without invoking the retry policy.
   *
   * @param request the request that was aborted.
   * @param error the error.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   */
  default RetryVerdict onRequestAbortedVerdict(
      @NonNull Request request, @NonNull Throwable error, int retryCount) {
    RetryDecision decision = onRequestAborted(request, error, retryCount);
    return () -> decision;
  }

  
Whether to retry when the server replied with a recoverable error (other than 
READ_TIMEOUT, WRITE_TIMEOUT or UNAVAILABLE). 
This can happen for the following errors: OverloadedException, ServerError, TruncateException, ReadFailureException, WriteFailureException. 
The following errors are handled internally by the driver, and therefore will never
be encountered in this method:



Note that this method will only be invoked for Request.isIdempotent() idempotent} requests: when execution was aborted before getting a response, it is impossible to determine with 100% certainty whether a mutation was applied or not, so a write is never safe to retry; the driver will rethrow the error directly, without invoking the retry policy. 
Params:
  • request – the request that failed.
  • error – the error.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
Deprecated:As of version 4.10, use onErrorResponseVerdict(Request, CoordinatorException, int) instead.
/**
   * Whether to retry when the server replied with a recoverable error (other than {@code
   * READ_TIMEOUT}, {@code WRITE_TIMEOUT} or {@code UNAVAILABLE}).
   *
   * <p>This can happen for the following errors: {@link OverloadedException}, {@link ServerError},
   * {@link TruncateException}, {@link ReadFailureException}, {@link WriteFailureException}.
   *
   * <p>The following errors are handled internally by the driver, and therefore will <b>never</b>
   * be encountered in this method:
   *
   * <ul>
   *   <li>{@link BootstrappingException}: always retried on the next node;
   *   <li>{@link QueryValidationException} (and its subclasses), {@link FunctionFailureException}
   *       and {@link ProtocolError}: always rethrown.
   * </ul>
   *
   * <p>Note that this method will only be invoked for {@link Request#isIdempotent()} idempotent}
   * requests: when execution was aborted before getting a response, it is impossible to determine
   * with 100% certainty whether a mutation was applied or not, so a write is never safe to retry;
   * the driver will rethrow the error directly, without invoking the retry policy.
   *
   * @param request the request that failed.
   * @param error the error.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   * @deprecated As of version 4.10, use {@link #onErrorResponseVerdict(Request,
   *     CoordinatorException, int)} instead.
   */
  @Deprecated
  RetryDecision onErrorResponse(
      @NonNull Request request, @NonNull CoordinatorException error, int retryCount);

  
Whether to retry when the server replied with a recoverable error (other than 
READ_TIMEOUT, WRITE_TIMEOUT or UNAVAILABLE). 
This can happen for the following errors: OverloadedException, ServerError, TruncateException, ReadFailureException, WriteFailureException. 
The following errors are handled internally by the driver, and therefore will never
be encountered in this method:



Note that this method will only be invoked for Request.isIdempotent() idempotent} requests: when execution was aborted before getting a response, it is impossible to determine with 100% certainty whether a mutation was applied or not, so a write is never safe to retry; the driver will rethrow the error directly, without invoking the retry policy. 
Params:
  • request – the request that failed.
  • error – the error.
  • retryCount – how many times the retry policy has been invoked already for this request
    (not counting the current invocation).
/**
   * Whether to retry when the server replied with a recoverable error (other than {@code
   * READ_TIMEOUT}, {@code WRITE_TIMEOUT} or {@code UNAVAILABLE}).
   *
   * <p>This can happen for the following errors: {@link OverloadedException}, {@link ServerError},
   * {@link TruncateException}, {@link ReadFailureException}, {@link WriteFailureException}.
   *
   * <p>The following errors are handled internally by the driver, and therefore will <b>never</b>
   * be encountered in this method:
   *
   * <ul>
   *   <li>{@link BootstrappingException}: always retried on the next node;
   *   <li>{@link QueryValidationException} (and its subclasses), {@link FunctionFailureException}
   *       and {@link ProtocolError}: always rethrown.
   * </ul>
   *
   * <p>Note that this method will only be invoked for {@link Request#isIdempotent()} idempotent}
   * requests: when execution was aborted before getting a response, it is impossible to determine
   * with 100% certainty whether a mutation was applied or not, so a write is never safe to retry;
   * the driver will rethrow the error directly, without invoking the retry policy.
   *
   * @param request the request that failed.
   * @param error the error.
   * @param retryCount how many times the retry policy has been invoked already for this request
   *     (not counting the current invocation).
   */
  default RetryVerdict onErrorResponseVerdict(
      @NonNull Request request, @NonNull CoordinatorException error, int retryCount) {
    RetryDecision decision = onErrorResponse(request, error, retryCount);
    return () -> decision;
  }

  
Called when the cluster that this policy is associated with closes. 
/** Called when the cluster that this policy is associated with closes. */
  @Override
  void close();
}