Github user kchilton2 commented on a diff in the pull request:
https://github.com/apache/incubator-rya/pull/172#discussion_r160547226
--- Diff:
extras/rya.indexing.pcj/src/main/java/org/apache/rya/indexing/pcj/storage/mongo/MongoPcjDocuments.java
---
@@ -0,0 +1,438 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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 org.apache.rya.indexing.pcj.storage.mongo;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.accumulo.core.security.Authorizations;
+import org.apache.rya.api.domain.RyaType;
+import org.apache.rya.api.resolver.RdfToRyaConversions;
+import org.apache.rya.api.resolver.RyaToRdfConversions;
+import org.apache.rya.indexing.pcj.storage.PcjMetadata;
+import
org.apache.rya.indexing.pcj.storage.PrecomputedJoinStorage.CloseableIterator;
+import
org.apache.rya.indexing.pcj.storage.PrecomputedJoinStorage.PCJStorageException;
+import org.apache.rya.indexing.pcj.storage.accumulo.PcjVarOrderFactory;
+import org.apache.rya.indexing.pcj.storage.accumulo.ShiftVarOrderFactory;
+import org.apache.rya.indexing.pcj.storage.accumulo.VariableOrder;
+import org.apache.rya.indexing.pcj.storage.accumulo.VisibilityBindingSet;
+import org.bson.Document;
+import org.bson.conversions.Bson;
+import org.openrdf.model.URI;
+import org.openrdf.model.Value;
+import org.openrdf.model.impl.URIImpl;
+import org.openrdf.query.BindingSet;
+import org.openrdf.query.MalformedQueryException;
+import org.openrdf.query.QueryEvaluationException;
+import org.openrdf.query.QueryLanguage;
+import org.openrdf.query.TupleQuery;
+import org.openrdf.query.TupleQueryResult;
+import org.openrdf.query.impl.MapBindingSet;
+import org.openrdf.repository.RepositoryConnection;
+import org.openrdf.repository.RepositoryException;
+
+import com.mongodb.MongoClient;
+import com.mongodb.client.FindIterable;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.util.JSON;
+
+/**
+ * Creates and modifies PCJs in MongoDB. PCJ's are stored as follows:
+ *
+ * <pre>
+ * <code>
+ * ----- PCJ Metadata Doc -----
+ * {
+ * _id: [table_name]_METADATA,
+ * sparql: [sparql query to match results],
+ * cardinality: [number of results]
+ * }
+ *
+ * ----- PCJ Results Doc -----
+ * {
+ * pcjName: [table_name],
+ * auths: [auths]
+ * [binding_var1]: {
+ * uri: [type_uri],
+ * value: value
+ * }
+ * .
+ * .
+ * .
+ * [binding_varn]: {
+ * uri: [type_uri],
+ * value: value
+ * }
+ * }
+ * </code>
+ * </pre>
+ */
+public class MongoPcjDocuments {
+ public static final String PCJ_COLLECTION_NAME = "pcjs";
+
+ // metadata fields
+ public static final String CARDINALITY_FIELD = "cardinality";
+ public static final String SPARQL_FIELD = "sparql";
+ public static final String PCJ_ID = "_id";
+ public static final String VAR_ORDER_ID = "varOrders";
+
+ // pcj results fields
+ private static final String BINDING_VALUE = "value";
+ private static final String BINDING_TYPE = "uri";
+ private static final String AUTHS_FIELD = "auths";
+ private static final String PCJ_NAME = "pcjName";
+
+ private final MongoCollection<Document> pcjCollection;
+ private static final PcjVarOrderFactory pcjVarOrderFactory = new
ShiftVarOrderFactory();
+
+ /**
+ * Creates a new {@link MongoPcjDocuments}.
+ * @param client - The {@link MongoClient} to use to connect to mongo.
+ * @param ryaInstanceName - The rya instance to connect to.
+ */
+ public MongoPcjDocuments(final MongoClient client, final String
ryaInstanceName) {
+ requireNonNull(client);
+ requireNonNull(ryaInstanceName);
+ pcjCollection =
client.getDatabase(ryaInstanceName).getCollection(PCJ_COLLECTION_NAME);
+ }
+
+ private String getMetadataID(final String pcjName) {
+ return pcjName + "_METADATA";
+ }
+
+ /**
+ * Creates a {@link Document} containing the metadata defining the PCj.
+ * @param pcjName - The name of the PCJ. (not null)
+ * @param sparql - The sparql query the PCJ will use.
+ * @return The document built around the provided metadata.
+ * @throws PCJStorageException - Thrown when the sparql query is
malformed.
+ */
+ public Document getMetadataDocument(final String pcjName, final String
sparql) throws PCJStorageException {
+ requireNonNull(pcjName);
+ requireNonNull(sparql);
+
+ final Set<VariableOrder> varOrders;
+ try {
+ varOrders = pcjVarOrderFactory.makeVarOrders(sparql);
+ } catch (final MalformedQueryException e) {
+ throw new PCJStorageException("Can not create the PCJ. The
SPARQL is malformed.", e);
+ }
+
+ return new Document()
+ .append(PCJ_ID, getMetadataID(pcjName))
+ .append(SPARQL_FIELD, sparql)
+ .append(CARDINALITY_FIELD, 0)
+ .append(VAR_ORDER_ID, varOrders);
+
+ }
+
+ /**
+ * Creates a new PCJ based on the provided metadata. The initial pcj
results will be empty.
+ * @param pcjName - The unique name of the PCJ.
+ * @param varOrders - The {@link VariableOrder}s.
+ * @param sparql - The query the pcj is assigned to.
+ * @throws @throws PCJStorageException - Thrown when the sparql query
is malformed.
+ */
+ public void createPcj(final String pcjName, final String sparql)
throws PCJStorageException {
+ pcjCollection.insertOne(getMetadataDocument(pcjName, sparql));
+ }
+
+ /**
+ * Creates a new PCJ document and populates it by scanning an instance
of
+ * Rya for historic matches.
+ * <p>
+ * If any portion of this operation fails along the way, the partially
+ * create PCJ table will be left in Accumulo.
+ *
+ * @param ryaConn - Connects to the Rya that will be scanned. (not
null)
+ * @param pcjTableName - The name of the PCJ table that will be
created. (not null)
+ * @param sparql - The SPARQL query whose results will be loaded into
the table. (not null)
+ * @throws PCJStorageException The PCJ table could not be create or the
+ * values from Rya were not able to be loaded into it.
+ */
+ public void createAndPopulatePcj(
+ final RepositoryConnection ryaConn,
+ final String pcjTableName,
+ final String sparql) throws PCJStorageException {
+ checkNotNull(pcjTableName);
+ checkNotNull(sparql);
+
+ // Create the PCJ document in Mongo.
+ createPcj(pcjTableName, sparql);
+
+ // Load historic matches from Rya into the PCJ table.
+ populatePcj(pcjTableName, ryaConn);
+ }
+
+ /**
+ * Gets the {@link PcjMetadata} from a provided PCJ name.
+ *
+ * @param pcjName - The PCJ to get from MongoDB. (not null)
+ * @return - The {@link PcjMetadata} of the Pcj specified.
+ * @throws PCJStorageException The PCJ Table does not exist.
+ */
+ public PcjMetadata getPcjMetadata(final String pcjName) throws
PCJStorageException {
+ requireNonNull(pcjName);
+
+ // since query by ID, there will only be one.
+ final Document result = pcjCollection.find(new Document(PCJ_ID,
getMetadataID(pcjName))).first();
+
+ if(result == null) {
+ throw new PCJStorageException("The PCJ: " + pcjName + " does
not exist.");
+ }
+
+ final String sparql = result.getString(SPARQL_FIELD);
+ final int cardinality = result.getInteger(CARDINALITY_FIELD, 0);
+ final List<List<String>> varOrders= (List<List<String>>)
result.get(VAR_ORDER_ID);
+ final Set<VariableOrder> varOrder = new HashSet<>();
+ for(final List<String> vars : varOrders) {
+ varOrder.add(new VariableOrder(vars));
+ }
+ //MongoDB does not need to use VarOrders
--- End diff --
Why is this comment here? What exactly are the variable orders being used
for?
---
