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/*
 * Copyright 2008-present MongoDB, 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.mongodb;

import com.mongodb.TaggableReadPreference.NearestReadPreference;
import com.mongodb.TaggableReadPreference.PrimaryPreferredReadPreference;
import com.mongodb.TaggableReadPreference.SecondaryPreferredReadPreference;
import com.mongodb.TaggableReadPreference.SecondaryReadPreference;
import com.mongodb.annotations.Immutable;
import com.mongodb.connection.ClusterDescription;
import com.mongodb.connection.ServerDescription;
import com.mongodb.lang.Nullable;
import org.bson.BsonDocument;
import org.bson.BsonString;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.TimeUnit;
import static com.mongodb.assertions.Assertions.notNull;
import static java.util.Collections.singletonList;
import static java.util.concurrent.TimeUnit.MILLISECONDS;

/**
 *  A class that represents preferred replica set members to which a query or command can be sent.
 *
 *  @mongodb.driver.manual core/read-preference  Read Preference
 *
 * @deprecated Usage of this API is not supported in AEM as a Cloud Service.
 */
@Immutable
@Deprecated(since = "2021-05-27")
public abstract class ReadPreference {

    ReadPreference() {
    }

    /**
     * True if this read preference allows reading from a secondary member of a replica set.
     *
     * @return if reading from a secondary is ok
     */
    public abstract boolean isSlaveOk();

    /**
     * Gets the name of this read preference.
     *
     * @return the name
     */
    public abstract String getName();

    /**
     * Gets a document representing this read preference in the wire protocol.
     *
     * @return the document
     */
    public abstract BsonDocument toDocument();

    /**
     * Chooses the servers from the given cluster than match this read preference.
     *
     * @param clusterDescription the cluster description
     * @return a list of matching server descriptions, which may be empty but may not be null
     */
    public final List choose(final ClusterDescription clusterDescription) {
        switch(clusterDescription.getType()) {
            case REPLICA_SET:
                return chooseForReplicaSet(clusterDescription);
            case SHARDED:
            case STANDALONE:
                return chooseForNonReplicaSet(clusterDescription);
            case UNKNOWN:
                return Collections.emptyList();
            default:
                throw new UnsupportedOperationException("Unsupported cluster type: " + clusterDescription.getType());
        }
    }

    protected abstract List chooseForNonReplicaSet(ClusterDescription clusterDescription);

    protected abstract List chooseForReplicaSet(ClusterDescription clusterDescription);

    /**
     * Gets a read preference that forces read to the primary.
     *
     * @return ReadPreference which reads from primary only
     */
    public static ReadPreference primary() {
        return PRIMARY;
    }

    /**
     * Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
     *
     * @return ReadPreference which reads primary if available.
     */
    public static ReadPreference primaryPreferred() {
        return PRIMARY_PREFERRED;
    }

    /**
     * Gets a read preference that forces reads to a secondary.
     *
     * @return ReadPreference which reads secondary.
     */
    public static ReadPreference secondary() {
        return SECONDARY;
    }

    /**
     * Gets a read preference that forces reads to a secondary if one is available, otherwise to the primary.
     *
     * @return ReadPreference which reads secondary if available, otherwise from primary.
     */
    public static ReadPreference secondaryPreferred() {
        return SECONDARY_PREFERRED;
    }

    /**
     * Gets a read preference that forces reads to a primary or a secondary.
     *
     * @return ReadPreference which reads nearest
     */
    public static ReadPreference nearest() {
        return NEAREST;
    }

    /**
     * Gets a read preference that forces reads to the primary if available, otherwise to a secondary.
     *
     * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency
     *                     plus 10 seconds, whichever is greatest.
     * @param timeUnit the time unit of maxStaleness
     * @return ReadPreference which reads primary if available.
     * @since 3.4
     * @see TaggableReadPreference#getMaxStaleness(TimeUnit)
     */
    public static ReadPreference primaryPreferred(final long maxStaleness, final TimeUnit timeUnit) {
        return new PrimaryPreferredReadPreference(Collections.emptyList(), maxStaleness, timeUnit);
    }

    /**
     * Gets a read preference that forces reads to a secondary that is less stale than the given maximum.
     *
     * 

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads secondary. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static ReadPreference secondary(final long maxStaleness, final TimeUnit timeUnit) { return new SecondaryReadPreference(Collections.emptyList(), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to a secondary that is less stale than the given maximumm if one is available, * otherwise to the primary. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads secondary if available, otherwise from primary. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static ReadPreference secondaryPreferred(final long maxStaleness, final TimeUnit timeUnit) { return new SecondaryPreferredReadPreference(Collections.emptyList(), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to a primary or a secondary that is less stale than the given maximum. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads nearest * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static ReadPreference nearest(final long maxStaleness, final TimeUnit timeUnit) { return new NearestReadPreference(Collections.emptyList(), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags. * * @param tagSet the set of tags to limit the list of secondaries to. * @return ReadPreference which reads primary if available, otherwise a secondary respective of tags.\ * @since 2.13 */ public static TaggableReadPreference primaryPreferred(final TagSet tagSet) { return new PrimaryPreferredReadPreference(singletonList(tagSet), null, MILLISECONDS); } /** * Gets a read preference that forces reads to a secondary with the given set of tags. * * @param tagSet the set of tags to limit the list of secondaries to * @return ReadPreference which reads secondary respective of tags. * @since 2.13 */ public static TaggableReadPreference secondary(final TagSet tagSet) { return new SecondaryReadPreference(singletonList(tagSet), null, MILLISECONDS); } /** * Gets a read preference that forces reads to a secondary with the given set of tags, or the primary is none are available. * * @param tagSet the set of tags to limit the list of secondaries to * @return ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags. * @since 2.13 */ public static TaggableReadPreference secondaryPreferred(final TagSet tagSet) { return new SecondaryPreferredReadPreference(singletonList(tagSet), null, MILLISECONDS); } /** * Gets a read preference that forces reads to the primary or a secondary with the given set of tags. * * @param tagSet the set of tags to limit the list of secondaries to * @return ReadPreference which reads nearest node respective of tags. * @since 2.13 */ public static TaggableReadPreference nearest(final TagSet tagSet) { return new NearestReadPreference(singletonList(tagSet), null, MILLISECONDS); } /** * Gets a read preference that forces reads to the primary if available, otherwise to a secondary with the given set of tags * that is less stale than the given maximum. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSet the set of tags to limit the list of secondaries to. * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads primary if available, otherwise a secondary respective of tags.\ * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference primaryPreferred(final TagSet tagSet, final long maxStaleness, final TimeUnit timeUnit) { return new PrimaryPreferredReadPreference(singletonList(tagSet), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to a secondary with the given set of tags that is less stale than the given maximum. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSet the set of tags to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads secondary respective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference secondary(final TagSet tagSet, final long maxStaleness, final TimeUnit timeUnit) { return new SecondaryReadPreference(singletonList(tagSet), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to a secondary with the given set of tags that is less stale than the given maximum, * or the primary is none are available. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSet the set of tags to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference secondaryPreferred(final TagSet tagSet, final long maxStaleness, final TimeUnit timeUnit) { return new SecondaryPreferredReadPreference(singletonList(tagSet), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to the primary or a secondary with the given set of tags that is less stale than the * given maximum. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSet the set of tags to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads nearest node respective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference nearest(final TagSet tagSet, final long maxStaleness, final TimeUnit timeUnit) { return new NearestReadPreference(singletonList(tagSet), maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags. * The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or failing if no secondary can be found that matches any of the tag sets in the list. * * @param tagSetList the list of tag sets to limit the list of secondaries to * @return ReadPreference which reads primary if available, otherwise a secondary respective of tags. * @since 2.13 */ public static TaggableReadPreference primaryPreferred(final List tagSetList) { return new PrimaryPreferredReadPreference(tagSetList, null, MILLISECONDS); } /** * Gets a read preference that forces reads to a secondary with one of the given sets of tags. * The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or failing if no secondary can be found that matches any of the tag sets in the list. * * @param tagSetList the list of tag sets to limit the list of secondaries to * @return ReadPreference which reads secondary respective of tags. * @since 2.13 */ public static TaggableReadPreference secondary(final List tagSetList) { return new SecondaryReadPreference(tagSetList, null, MILLISECONDS); } /** * Gets a read preference that forces reads to a secondary with one of the given sets of tags. * The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or the primary if none are available. * * @param tagSetList the list of tag sets to limit the list of secondaries to * @return ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags. * @since 2.13 */ public static TaggableReadPreference secondaryPreferred(final List tagSetList) { return new SecondaryPreferredReadPreference(tagSetList, null, MILLISECONDS); } /** * Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags. * The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or the primary if none are available. * * @param tagSetList the list of tag sets to limit the list of secondaries to * @return ReadPreference which reads nearest node respective of tags. * @since 2.13 */ public static TaggableReadPreference nearest(final List tagSetList) { return new NearestReadPreference(tagSetList, null, MILLISECONDS); } /** * Gets a read preference that forces reads to the primary if available, otherwise to a secondary with one of the given sets of tags * that is less stale than the given maximum. * *

* The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or failing if no secondary can be found that matches any of the tag sets in the list. *

* *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSetList the list of tag sets to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads primary if available, otherwise a secondary respective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference primaryPreferred(final List tagSetList, final long maxStaleness, final TimeUnit timeUnit) { return new PrimaryPreferredReadPreference(tagSetList, maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to a secondary with one of the given sets of tags that is less stale than * the given maximum. * *

* The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or failing if no secondary can be found that matches any of the tag sets in the list. *

* *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSetList the list of tag sets to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads secondary respective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference secondary(final List tagSetList, final long maxStaleness, final TimeUnit timeUnit) { return new SecondaryReadPreference(tagSetList, maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to a secondary with one of the given sets of tags that is less stale than * the given maximum. * *

* The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or the primary if none are available. *

* *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSetList the list of tag sets to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads secondary if available respective of tags, otherwise from primary irrespective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference secondaryPreferred(final List tagSetList, final long maxStaleness, final TimeUnit timeUnit) { return new SecondaryPreferredReadPreference(tagSetList, maxStaleness, timeUnit); } /** * Gets a read preference that forces reads to the primary or a secondary with one of the given sets of tags that is less stale than * the given maximum. * *

* The driver will look for a secondary with each tag set in the given list, stopping after one is found, * or the primary if none are available. *

* *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param tagSetList the list of tag sets to limit the list of secondaries to * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return ReadPreference which reads nearest node respective of tags. * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference nearest(final List tagSetList, final long maxStaleness, final TimeUnit timeUnit) { return new NearestReadPreference(tagSetList, maxStaleness, timeUnit); } /** * Creates a read preference from the given read preference name. * * @param name the name of the read preference * @return the read preference */ public static ReadPreference valueOf(final String name) { notNull("name", name); String nameToCheck = name.toLowerCase(); if (nameToCheck.equals(PRIMARY.getName().toLowerCase())) { return PRIMARY; } if (nameToCheck.equals(SECONDARY.getName().toLowerCase())) { return SECONDARY; } if (nameToCheck.equals(SECONDARY_PREFERRED.getName().toLowerCase())) { return SECONDARY_PREFERRED; } if (nameToCheck.equals(PRIMARY_PREFERRED.getName().toLowerCase())) { return PRIMARY_PREFERRED; } if (nameToCheck.equals(NEAREST.getName().toLowerCase())) { return NEAREST; } throw new IllegalArgumentException("No match for read preference of " + name); } /** * Creates a taggable read preference from the given read preference name and list of tag sets. * * @param name the name of the read preference * @param tagSetList the list of tag sets * @return the taggable read preference * @since 2.13 */ public static TaggableReadPreference valueOf(final String name, final List tagSetList) { return valueOf(name, tagSetList, null, MILLISECONDS); } /** * Creates a taggable read preference from the given read preference name, list of tag sets, and max allowable staleness of secondaries. * *

* The driver estimates the staleness of each secondary, based on lastWriteDate values provided in server isMaster responses, * and selects only those secondaries whose staleness is less than or equal to maxStaleness. *

* * @param name the name of the read preference * @param tagSetList the list of tag sets * @param maxStaleness the max allowable staleness of secondaries. The minimum value is either 90 seconds, or the heartbeat frequency * plus 10 seconds, whichever is greatest. * @param timeUnit the time unit of maxStaleness * @return the taggable read preference * @since 3.4 * @see TaggableReadPreference#getMaxStaleness(TimeUnit) */ public static TaggableReadPreference valueOf(final String name, final List tagSetList, final long maxStaleness, final TimeUnit timeUnit) { return valueOf(name, tagSetList, (Long) maxStaleness, timeUnit); } private static TaggableReadPreference valueOf(final String name, final List tagSetList, @Nullable final Long maxStaleness, final TimeUnit timeUnit) { notNull("name", name); notNull("tagSetList", tagSetList); notNull("timeUnit", timeUnit); String nameToCheck = name.toLowerCase(); if (nameToCheck.equals(PRIMARY.getName().toLowerCase())) { throw new IllegalArgumentException("Primary read preference can not also specify tag sets or max staleness"); } if (nameToCheck.equals(SECONDARY.getName().toLowerCase())) { return new SecondaryReadPreference(tagSetList, maxStaleness, timeUnit); } if (nameToCheck.equals(SECONDARY_PREFERRED.getName().toLowerCase())) { return new SecondaryPreferredReadPreference(tagSetList, maxStaleness, timeUnit); } if (nameToCheck.equals(PRIMARY_PREFERRED.getName().toLowerCase())) { return new PrimaryPreferredReadPreference(tagSetList, maxStaleness, timeUnit); } if (nameToCheck.equals(NEAREST.getName().toLowerCase())) { return new NearestReadPreference(tagSetList, maxStaleness, timeUnit); } throw new IllegalArgumentException("No match for read preference of " + name); } /** * Preference to read from primary only. Cannot be combined with tags. * * @deprecated Usage of this API is not supported in AEM as a Cloud Service. */ @Deprecated(since = "2021-05-27") private static final class PrimaryReadPreference extends ReadPreference { private PrimaryReadPreference() { } @Override public boolean isSlaveOk() { return false; } @Override public String toString() { return getName(); } @Override public boolean equals(final Object o) { return o != null && getClass() == o.getClass(); } @Override public int hashCode() { return getName().hashCode(); } public BsonDocument toDocument() { return new BsonDocument("mode", new BsonString(getName())); } @Override @SuppressWarnings("deprecation") protected List chooseForReplicaSet(final ClusterDescription clusterDescription) { return clusterDescription.getPrimaries(); } @Override @SuppressWarnings("deprecation") protected List chooseForNonReplicaSet(final ClusterDescription clusterDescription) { return clusterDescription.getAny(); } @Override public String getName() { return "primary"; } } private static final ReadPreference PRIMARY; private static final ReadPreference SECONDARY; private static final ReadPreference SECONDARY_PREFERRED; private static final ReadPreference PRIMARY_PREFERRED; private static final ReadPreference NEAREST; static { PRIMARY = new PrimaryReadPreference(); SECONDARY = new SecondaryReadPreference(); SECONDARY_PREFERRED = new SecondaryPreferredReadPreference(); PRIMARY_PREFERRED = new PrimaryPreferredReadPreference(); NEAREST = new NearestReadPreference(); } }




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