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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.operation;

import com.mongodb.ExplainVerbosity;
import com.mongodb.MongoNamespace;
import com.mongodb.async.AsyncBatchCursor;
import com.mongodb.async.SingleResultCallback;
import com.mongodb.binding.AsyncConnectionSource;
import com.mongodb.binding.AsyncReadBinding;
import com.mongodb.binding.ConnectionSource;
import com.mongodb.binding.ReadBinding;
import com.mongodb.client.model.Collation;
import com.mongodb.connection.AsyncConnection;
import com.mongodb.connection.Connection;
import com.mongodb.connection.ConnectionDescription;
import com.mongodb.connection.ServerDescription;
import com.mongodb.internal.client.model.CountStrategy;
import com.mongodb.internal.connection.NoOpSessionContext;
import com.mongodb.operation.CommandOperationHelper.CommandReadTransformer;
import com.mongodb.operation.CommandOperationHelper.CommandReadTransformerAsync;
import com.mongodb.session.SessionContext;
import org.bson.BsonDocument;
import org.bson.BsonInt32;
import org.bson.BsonInt64;
import org.bson.BsonString;
import org.bson.BsonValue;
import org.bson.codecs.BsonDocumentCodec;
import org.bson.codecs.Decoder;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

import static com.mongodb.assertions.Assertions.notNull;
import static com.mongodb.operation.CommandOperationHelper.CommandCreator;
import static com.mongodb.operation.CommandOperationHelper.executeCommandAsync;
import static com.mongodb.operation.CommandOperationHelper.executeCommand;
import static com.mongodb.operation.DocumentHelper.putIfNotNull;
import static com.mongodb.operation.DocumentHelper.putIfNotZero;
import static com.mongodb.operation.ExplainHelper.asExplainCommand;
import static com.mongodb.operation.OperationHelper.validateReadConcernAndCollation;
import static com.mongodb.operation.OperationReadConcernHelper.appendReadConcernToCommand;

/**
 * An operation that executes a count.
 *
 * @since 3.0
 */
@Deprecated
public class CountOperation implements AsyncReadOperation, ReadOperation {
    private static final Decoder DECODER = new BsonDocumentCodec();
    private final MongoNamespace namespace;
    private final CountStrategy countStrategy;
    private boolean retryReads;
    private BsonDocument filter;
    private BsonValue hint;
    private long skip;
    private long limit;
    private long maxTimeMS;
    private Collation collation;

    /**
     * Construct a new instance.
     *
     * @param namespace the database and collection namespace for the operation.
     */
    public CountOperation(final MongoNamespace namespace) {
        this(namespace, CountStrategy.COMMAND);
    }

    /**
     * Construct a new instance.
     *
     * @param namespace     the database and collection namespace for the operation.
     * @param countStrategy the strategy to use for calculating the count.
     */
    public CountOperation(final MongoNamespace namespace, final CountStrategy countStrategy) {
        this.namespace = notNull("namespace", namespace);
        this.countStrategy = notNull("countStrategy", countStrategy);
    }

    /**
     * Gets the query filter.
     *
     * @return the query filter
     * @mongodb.driver.manual reference/method/db.collection.find/ filter
     */
    public BsonDocument getFilter() {
        return filter;
    }

    /**
     * Sets the filter to apply to the query.
     *
     * @param filter the filter, which may be null.
     * @return this
     * @mongodb.driver.manual reference/method/db.collection.find/ Filter
     */
    public CountOperation filter(final BsonDocument filter) {
        this.filter = filter;
        return this;
    }

    /**
     * Enables retryable reads if a read fails due to a network error.
     *
     * @param retryReads true if reads should be retried
     * @return this
     * @since 3.11
     */
    public CountOperation retryReads(final boolean retryReads) {
        this.retryReads = retryReads;
        return this;
    }

    /**
     * Gets the value for retryable reads. The default is true.
     *
     * @return the retryable reads value
     * @since 3.11
     */
    public boolean getRetryReads() {
        return retryReads;
    }

    /**
     * Gets the hint to apply.
     *
     * @return the hint, which should describe an existing
     */
    public BsonValue getHint() {
        return hint;
    }

    /**
     * Sets the hint to apply.
     *
     * @param hint a value describing the index which should be used for this operation.
     * @return this
     */
    public CountOperation hint(final BsonValue hint) {
        this.hint = hint;
        return this;
    }

    /**
     * Gets the limit to apply.  The default is 0, which means there is no limit.
     *
     * @return the limit
     * @mongodb.driver.manual reference/method/cursor.limit/#cursor.limit Limit
     */
    public long getLimit() {
        return limit;
    }

    /**
     * Sets the limit to apply.
     *
     * @param limit the limit
     * @return this
     * @mongodb.driver.manual reference/method/cursor.limit/#cursor.limit Limit
     */
    public CountOperation limit(final long limit) {
        this.limit = limit;
        return this;
    }

    /**
     * Gets the number of documents to skip.  The default is 0.
     *
     * @return the number of documents to skip, which may be null
     * @mongodb.driver.manual reference/method/cursor.skip/#cursor.skip Skip
     */
    public long getSkip() {
        return skip;
    }

    /**
     * Sets the number of documents to skip.
     *
     * @param skip the number of documents to skip
     * @return this
     * @mongodb.driver.manual reference/method/cursor.skip/#cursor.skip Skip
     */
    public CountOperation skip(final long skip) {
        this.skip = skip;
        return this;
    }

    /**
     * Gets the maximum execution time on the server for this operation.  The default is 0, which places no limit on the execution time.
     *
     * @param timeUnit the time unit to return the result in
     * @return the maximum execution time in the given time unit
     */
    public long getMaxTime(final TimeUnit timeUnit) {
        notNull("timeUnit", timeUnit);
        return timeUnit.convert(maxTimeMS, TimeUnit.MILLISECONDS);
    }

    /**
     * Sets the maximum execution time on the server for this operation.
     *
     * @param maxTime  the max time
     * @param timeUnit the time unit, which may not be null
     * @return this
     */
    public CountOperation maxTime(final long maxTime, final TimeUnit timeUnit) {
        notNull("timeUnit", timeUnit);
        this.maxTimeMS = TimeUnit.MILLISECONDS.convert(maxTime, timeUnit);
        return this;
    }

    /**
     * Returns the collation options
     *
     * @return the collation options
     * @since 3.4
     * @mongodb.server.release 3.4
     */
    public Collation getCollation() {
        return collation;
    }

    /**
     * Sets the collation options
     *
     * 

A null value represents the server default.

* @param collation the collation options to use * @return this */ public CountOperation collation(final Collation collation) { this.collation = collation; return this; } @Override public Long execute(final ReadBinding binding) { if (countStrategy.equals(CountStrategy.COMMAND)) { return executeCommand(binding, namespace.getDatabaseName(), getCommandCreator(binding.getSessionContext()), DECODER, transformer(), retryReads); } else { BatchCursor cursor = getAggregateOperation().execute(binding); return cursor.hasNext() ? getCountFromAggregateResults(cursor.next()) : 0; } } @Override public void executeAsync(final AsyncReadBinding binding, final SingleResultCallback callback) { if (countStrategy.equals(CountStrategy.COMMAND)) { executeCommandAsync(binding, namespace.getDatabaseName(), getCommandCreator(binding.getSessionContext()), DECODER, asyncTransformer(), retryReads, callback); } else { getAggregateOperation().executeAsync(binding, new SingleResultCallback>(){ @Override public void onResult(final AsyncBatchCursor result, final Throwable t) { if (t != null) { callback.onResult(null, t); } else { result.next(new SingleResultCallback>() { @Override public void onResult(final List result, final Throwable t) { if (t != null) { callback.onResult(null, t); } else { callback.onResult(getCountFromAggregateResults(result), null); } } }); } } }); } } /** * Gets an operation whose execution explains this operation. * * @param explainVerbosity the explain verbosity * @return a read operation that when executed will explain this operation */ public ReadOperation asExplainableOperation(final ExplainVerbosity explainVerbosity) { if (countStrategy.equals(CountStrategy.COMMAND)) { return createExplainableOperation(explainVerbosity); } else { return getAggregateOperation().asExplainableOperation(explainVerbosity); } } /** * Gets an operation whose execution explains this operation. * * @param explainVerbosity the explain verbosity * @return a read operation that when executed will explain this operation */ public AsyncReadOperation asExplainableOperationAsync(final ExplainVerbosity explainVerbosity) { if (countStrategy.equals(CountStrategy.COMMAND)) { return createExplainableOperation(explainVerbosity); } else { return getAggregateOperation().asExplainableOperationAsync(explainVerbosity); } } private CommandReadOperation createExplainableOperation(final ExplainVerbosity explainVerbosity) { return new CommandReadOperation(namespace.getDatabaseName(), asExplainCommand(getCommand(NoOpSessionContext.INSTANCE), explainVerbosity), new BsonDocumentCodec()); } private CommandReadTransformer transformer() { return new CommandReadTransformer() { @Override public Long apply(final BsonDocument result, final ConnectionSource source, final Connection connection) { return (result.getNumber("n")).longValue(); } }; } private CommandReadTransformerAsync asyncTransformer() { return new CommandReadTransformerAsync() { @Override public Long apply(final BsonDocument result, final AsyncConnectionSource source, final AsyncConnection connection) { return (result.getNumber("n")).longValue(); } }; } private CommandCreator getCommandCreator(final SessionContext sessionContext) { return new CommandCreator() { @Override public BsonDocument create(final ServerDescription serverDescription, final ConnectionDescription connectionDescription) { validateReadConcernAndCollation(connectionDescription, sessionContext.getReadConcern(), collation); return getCommand(sessionContext); } }; } private BsonDocument getCommand(final SessionContext sessionContext) { BsonDocument document = new BsonDocument("count", new BsonString(namespace.getCollectionName())); appendReadConcernToCommand(sessionContext, document); putIfNotNull(document, "query", filter); putIfNotZero(document, "limit", limit); putIfNotZero(document, "skip", skip); putIfNotNull(document, "hint", hint); putIfNotZero(document, "maxTimeMS", maxTimeMS); if (collation != null) { document.put("collation", collation.asDocument()); } return document; } private AggregateOperation getAggregateOperation() { return new AggregateOperation(namespace, getPipeline(), DECODER) .retryReads(retryReads) .collation(collation) .hint(hint) .maxTime(maxTimeMS, TimeUnit.MILLISECONDS); } private List getPipeline() { ArrayList pipeline = new ArrayList(); pipeline.add(new BsonDocument("$match", filter != null ? filter : new BsonDocument())); if (skip > 0) { pipeline.add(new BsonDocument("$skip", new BsonInt64(skip))); } if (limit > 0) { pipeline.add(new BsonDocument("$limit", new BsonInt64(limit))); } pipeline.add(new BsonDocument("$group", new BsonDocument("_id", new BsonInt32(1)) .append("n", new BsonDocument("$sum", new BsonInt32(1))))); return pipeline; } private Long getCountFromAggregateResults(final List results) { if (results == null || results.isEmpty()) { return 0L; } else { return results.get(0).getNumber("n").longValue(); } } }




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