apps/scholexplorer-api/pom.xml

@@ -30,6 +30,11 @@
             <artifactId>dhp-schemas</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-pool2</artifactId>
+        </dependency>
+
     </dependencies>
 
 

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/MainApplication.java

@@ -42,11 +42,6 @@ public class MainApplication extends AbstractDnetApp {
 	@Value("${dhp.swagger.api.basePath}")
 	private String swaggerPath;
 
-	final String descriptionAPI = " <p style=\"text-align:center;\"><img src=\"/logo.png\" alt=\"ScholeXplorer\"> </p>" +
-			"The Scholix Swagger API allows clients to run REST queries over the Scholexplorer index in order to fetch links matching given criteria. In the current version, clients can search for:" +
-			"<ul><li>Links whose source object has a given PID or PID type</li>" +
-			"<li>Links whose source object has been published by a given data source (\"data source as publisher\")</li>" +
-			"<li>Links that were collected from a given data source (\"data source as provider\").</li></ul>";
 
 	public static void main(final String[] args) {
 		SpringApplication.run(MainApplication.class, args);
@@ -57,20 +52,17 @@ public class MainApplication extends AbstractDnetApp {
 	@Bean
 	public TaggedCounter myCounter(MeterRegistry meterRegistry) {
 
-		return new TaggedCounter("scholixLinkCounter", "links",meterRegistry);
+		return new TaggedCounter(ScholixAPIConstants.SCHOLIX_MANAGER_COUNTER_NAME, ScholixAPIConstants.SCHOLIX_MANAGER_TAG_NAME,meterRegistry);
 	}
 
 	@Bean
 	public TimedAspect timedAspect(MeterRegistry meterRegistry) {
-
-
 		MeterFilter mf = new MeterFilter() {
 			@Override
 			public DistributionStatisticConfig configure(Meter.Id id, DistributionStatisticConfig config) {
-				if (id.getName().startsWith("scholix")) {
+				if (id.getName().startsWith(ScholixAPIConstants.SCHOLIX_COUNTER_PREFIX)) {
 
 					return DistributionStatisticConfig.builder()
-							.percentiles(0.20, 0.50, 0.75,0.95)
 							.percentilesHistogram(false)
 							.serviceLevelObjectives( histogramValues)
 							.build()
@@ -79,31 +71,24 @@ public class MainApplication extends AbstractDnetApp {
 				return config;
 			}
 		};
-
-
 		meterRegistry.config().meterFilter(mf);
-
-
-
 		return new TimedAspect(meterRegistry);
 	}
 
 
-
-
 	@Override
 	protected void configSwagger(final Docket docket) {
 		docket
 			.host(swaggetHost)
 			.pathMapping(swaggerPath)
-			.groupName("Scholexplorer V1")
+			.groupName(ScholixAPIConstants.API_V1_NAME)
 			.select()
 			.apis(RequestHandlerSelectors.any())
 			.paths(p -> p.startsWith("/v1"))
 			.build()
 			.apiInfo(new ApiInfoBuilder()
-				.title("Scholexplorer API V1.0")
+				.title(ScholixAPIConstants.API_V1_NAME)
-				.description(descriptionAPI)
+				.description(ScholixAPIConstants.API_DESCRIPTION)
 				.version("1.0")
 				.contact(ApiInfo.DEFAULT_CONTACT)
 				.license("Apache 2.0")
@@ -113,23 +98,20 @@ public class MainApplication extends AbstractDnetApp {
 
 
 
-	@Bean (name = "SpringDOcketv2")
+	@Bean (name = "SpringDocketv2")
 	public Docket v2Docket() {
-
-
 		final Docket docket = new Docket(DocumentationType.SWAGGER_2);
-
 		docket
 				.host(swaggetHost)
 				.pathMapping(swaggerPath)
-				.groupName("Scholexplorer V2")
+				.groupName(ScholixAPIConstants.API_V2_NAME)
 				.select()
 				.apis(RequestHandlerSelectors.any())
 				.paths(p -> p.startsWith("/v2"))
 				.build()
 				.apiInfo(new ApiInfoBuilder()
-						.title("Scholexplorer API V2.0")
+						.title(ScholixAPIConstants.API_V2_NAME)
-						.description(descriptionAPI)
+						.description(ScholixAPIConstants.API_DESCRIPTION)
 						.version("2.0")
 						.contact(ApiInfo.DEFAULT_CONTACT)
 						.license("Apache 2.0")

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/RestClientConfig.java

@@ -1,5 +1,6 @@
 package eu.dnetlib.scholix.api;
 
+import eu.dnetlib.scholix.api.index.ElasticSearchPool;
 import eu.dnetlib.scholix.api.index.ElasticSearchProperties;
 import org.elasticsearch.client.RestHighLevelClient;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -12,20 +13,29 @@ import org.springframework.data.elasticsearch.config.AbstractElasticsearchConfig
 import java.time.Duration;
 
 @Configuration
-public class RestClientConfig extends AbstractElasticsearchConfiguration {
+public class RestClientConfig  {
 
     @Autowired
     private ElasticSearchProperties elasticSearchProperties;
 
-    @Override
-    @Bean
-        public RestHighLevelClient elasticsearchClient() {
 
-        final ClientConfiguration clientConfiguration = ClientConfiguration.builder()
+    @Bean
-                .connectedTo(elasticSearchProperties.getClusterNodes().split(","))
+    public ElasticSearchPool connectionPool() {
-                .withConnectTimeout(elasticSearchProperties.getConnectionTimeout())
+
-                .withSocketTimeout(elasticSearchProperties.getSocketTimeout())
+        ElasticSearchPool pool = new ElasticSearchPool(elasticSearchProperties);
-                .build();
+        return pool;
-        return RestClients.create(clientConfiguration).rest();
     }
+
+
+//    @Override
+//    @Bean
+//        public RestHighLevelClient elasticsearchClient() {
+//
+//        final ClientConfiguration clientConfiguration = ClientConfiguration.builder()
+//                .connectedTo(elasticSearchProperties.getClusterNodes().split(","))
+//                .withConnectTimeout(elasticSearchProperties.getConnectionTimeout())
+//                .withSocketTimeout(elasticSearchProperties.getSocketTimeout())
+//                .build();
+//        return RestClients.create(clientConfiguration).rest();
+//    }
 }

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/ScholixAPIConstants.java

@@ -0,0 +1,23 @@
+package eu.dnetlib.scholix.api;
+
+public class ScholixAPIConstants {
+
+    public static final String API_V1_NAME = "Scholexplorer API V1.0";
+    public static final String API_V2_NAME = "Scholexplorer API V2.0";
+
+    public static String API_DESCRIPTION =" <p style=\"text-align:center;\"><img src=\"/logo.png\" alt=\"ScholeXplorer\"> </p>" +
+            "The Scholix Swagger API allows clients to run REST queries over the Scholexplorer index in order to fetch links matching given criteria. In the current version, clients can search for:" +
+            "<ul><li>Links whose source object has a given PID or PID type</li>" +
+            "<li>Links whose source object has been published by a given data source (\"data source as publisher\")</li>" +
+            "<li>Links that were collected from a given data source (\"data source as provider\").</li></ul>";
+
+
+    public static  String SCHOLIX_MANAGER_COUNTER_NAME= "scholixLinkCounter";
+    public static final String SCHOLIX_MANAGER_TAG_NAME = "links";
+
+    public static String SCHOLIX_COUNTER_PREFIX = "scholix";
+
+
+
+
+}

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/controller/ScholixControllerV2.java

@@ -4,6 +4,7 @@ package eu.dnetlib.scholix.api.controller;
 import eu.dnetlib.common.controller.AbstractDnetController;
 import eu.dnetlib.dhp.schema.sx.scholix.ScholixIdentifier;
 import eu.dnetlib.scholix.api.ScholixAPIVersion;
+import eu.dnetlib.scholix.api.ScholixException;
 import eu.dnetlib.scholix.api.index.ScholixIndexManager;
 import eu.dnetlib.scholix.api.model.v2.PageResultType;
 import eu.dnetlib.scholix.api.model.v2.ScholixType;
@@ -13,6 +14,7 @@ import io.swagger.annotations.ApiOperation;
 import io.swagger.v3.oas.annotations.Parameter;
 import io.swagger.v3.oas.annotations.enums.ParameterIn;
 import eu.dnetlib.dhp.schema.sx.scholix.Scholix;
+import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.lucene.search.join.ScoreMode;
 import org.elasticsearch.index.query.BoolQueryBuilder;
@@ -77,19 +79,20 @@ public class ScholixControllerV2 extends AbstractDnetController {
             @Parameter(in = ParameterIn.QUERY,
                     description = "select page of result")  Integer page) throws Exception {
 
+        if (StringUtils.isEmpty(sourcePid) && StringUtils.isEmpty(targetPid) && StringUtils.isEmpty(sourcePublisher)&& StringUtils.isEmpty(targetPublisher)&& StringUtils.isEmpty(linkProvider))
+            throw new ScholixException("The method requires one of the following parameters: sourcePid, targetPid, sourcePublisher, targetPublisher, linkProvider");
 
-
+        try {
             final int currentPage = page != null ? page : 0;
-
-        System.out.println(currentPage);
             Pair<Long, List<Scholix>> scholixResult = manager.linksFromPid(ScholixAPIVersion.V2, linkProvider, targetPid, targetPidType, targetPublisher, targetType, sourcePid, sourcePidType, sourcePublisher, sourceType, harvestedAfter, currentPage);
-
             final PageResultType pageResult = new PageResultType();
             pageResult.setTotalPages(scholixResult.getLeft().intValue() / 10);
             pageResult.setTotalLinks(scholixResult.getLeft().intValue());
             pageResult.setResult(scholixResult.getRight().stream().map(ScholixType::fromScholix).collect(Collectors.toList()));
-
             return pageResult;
+        } catch (Throwable e) {
+            throw new ScholixException("Error on requesting url ", e);
+        }
     }
 
 

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/index/ElasticSearchClientFactory.java

@@ -0,0 +1,66 @@
+package eu.dnetlib.scholix.api.index;
+
+import org.apache.commons.pool2.PooledObject;
+import org.apache.commons.pool2.PooledObjectFactory;
+import org.apache.commons.pool2.impl.DefaultPooledObject;
+import org.elasticsearch.client.RequestOptions;
+import org.elasticsearch.client.RestHighLevelClient;
+import org.springframework.data.elasticsearch.client.ClientConfiguration;
+import org.springframework.data.elasticsearch.client.RestClients;
+
+public class ElasticSearchClientFactory implements PooledObjectFactory<RestHighLevelClient> {
+
+    private ElasticSearchProperties elasticSearchProperties;
+
+
+    public ElasticSearchClientFactory(final  ElasticSearchProperties elasticSearchProperties){
+        this.elasticSearchProperties = elasticSearchProperties;
+
+    }
+
+    public PooledObject<RestHighLevelClient> makeObject() throws Exception {
+
+
+
+        final ClientConfiguration clientConfiguration = ClientConfiguration.builder()
+                .connectedTo(elasticSearchProperties.getClusterNodes().split(","))
+                .withConnectTimeout(elasticSearchProperties.getConnectionTimeout())
+                .withSocketTimeout(elasticSearchProperties.getSocketTimeout())
+                .build();
+        RestHighLevelClient cc = RestClients.create(clientConfiguration).rest();
+
+
+        return new DefaultPooledObject(cc);
+    }
+
+    public void destroyObject(PooledObject<RestHighLevelClient> pooledObject) throws Exception {
+        RestHighLevelClient client = pooledObject.getObject();
+        if(client!=null&&client.ping(RequestOptions.DEFAULT)){
+            try {
+                client.close();
+            }catch (Exception e){
+                //ignore
+            }
+        }
+    }
+
+    public boolean validateObject(PooledObject<RestHighLevelClient> pooledObject) {
+        RestHighLevelClient client = pooledObject.getObject();
+        try {
+            return client.ping(RequestOptions.DEFAULT);
+        }catch(Exception e){
+            return false;
+        }
+    }
+
+    public void activateObject(PooledObject<RestHighLevelClient> pooledObject) throws Exception {
+        RestHighLevelClient client = pooledObject.getObject();
+        boolean response = client.ping(RequestOptions.DEFAULT);
+    }
+
+    public void passivateObject(PooledObject<RestHighLevelClient> pooledObject) throws Exception {
+        //nothing
+    }
+
+
+}

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/index/ElasticSearchPool.java

@@ -0,0 +1,19 @@
+package eu.dnetlib.scholix.api.index;
+
+import org.elasticsearch.client.RestHighLevelClient;
+
+public class ElasticSearchPool extends Pool<RestHighLevelClient> {
+
+    private final ElasticSearchProperties elasticSearchProperties;
+
+    public ElasticSearchPool(ElasticSearchProperties elasticSearchProperties){
+        super(elasticSearchProperties, new ElasticSearchClientFactory(elasticSearchProperties));
+        this.elasticSearchProperties = elasticSearchProperties;
+    }
+
+    public ElasticSearchProperties getElasticSearchProperties() {
+        return elasticSearchProperties;
+    }
+}
+
+

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/index/ElasticSearchProperties.java

@@ -1,5 +1,6 @@
 package eu.dnetlib.scholix.api.index;
 
+import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.stereotype.Component;
 
@@ -10,7 +11,7 @@ import javax.validation.constraints.NotNull;
  */
 @Component("elasticSearchProperties")
 @ConfigurationProperties(prefix = "scholix.elastic")
-public class ElasticSearchProperties {
+public class ElasticSearchProperties extends GenericObjectPoolConfig {
 
 	@NotNull
 	private String clusterNodes;

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/index/Pool.java

@@ -0,0 +1,138 @@
+package eu.dnetlib.scholix.api.index;
+
+import eu.dnetlib.scholix.api.ScholixException;
+import org.apache.commons.pool2.PooledObjectFactory;
+import org.apache.commons.pool2.impl.GenericObjectPool;
+import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
+
+public class Pool<T> implements Cloneable {
+
+    protected GenericObjectPool<T> internalPool ;
+
+    public Pool(){
+        super();
+    }
+
+    public Pool(final GenericObjectPoolConfig poolConfig, PooledObjectFactory<T> factory){
+        initPool(poolConfig, factory);
+    }
+
+    public void initPool(final GenericObjectPoolConfig poolConfig, PooledObjectFactory<T> factory) {
+
+        if (this.internalPool != null) {
+            try {
+                closeInternalPool();
+            } catch (Exception e) {
+            }
+        }
+
+        this.internalPool = new GenericObjectPool<T>(factory, poolConfig);
+    }
+
+    protected void closeInternalPool() throws ScholixException {
+        try {
+            internalPool.close();
+        } catch (Exception e) {
+            throw new ScholixException("Could not destroy the pool", e);
+        }
+    }
+
+    public T getResource() throws ScholixException {
+        try {
+            return internalPool.borrowObject();
+        } catch (Exception e) {
+            throw new ScholixException("Could not get a resource from the pool", e);
+        }
+    }
+
+
+    public void returnResource(final T resource) throws ScholixException {
+        if (resource != null) {
+            returnResourceObject(resource);
+        }
+    }
+
+    private void returnResourceObject(final T resource) throws ScholixException {
+        if (resource == null) {
+            return;
+        }
+        try {
+            internalPool.returnObject(resource);
+        } catch (Exception e) {
+            throw new ScholixException("Could not return the resource to the pool", e);
+        }
+    }
+
+    public void returnBrokenResource(final T resource) throws ScholixException {
+        if (resource != null) {
+            returnBrokenResourceObject(resource);
+        }
+    }
+
+    private void returnBrokenResourceObject(T resource) throws ScholixException {
+        try {
+            internalPool.invalidateObject(resource);
+        } catch (Exception e) {
+            throw new ScholixException("Could not return the resource to the pool", e);
+        }
+    }
+
+    public void destroy() throws ScholixException {
+        closeInternalPool();
+    }
+
+
+    public int getNumActive() {
+        if (poolInactive()) {
+            return -1;
+        }
+
+        return this.internalPool.getNumActive();
+    }
+
+    public int getNumIdle() {
+        if (poolInactive()) {
+            return -1;
+        }
+
+        return this.internalPool.getNumIdle();
+    }
+
+    public int getNumWaiters() {
+        if (poolInactive()) {
+            return -1;
+        }
+
+        return this.internalPool.getNumWaiters();
+    }
+
+    public long getMeanBorrowWaitTimeMillis() {
+        if (poolInactive()) {
+            return -1;
+        }
+
+        return this.internalPool.getMeanBorrowWaitTimeMillis();
+    }
+
+    public long getMaxBorrowWaitTimeMillis() {
+        if (poolInactive()) {
+            return -1;
+        }
+
+        return this.internalPool.getMaxBorrowWaitTimeMillis();
+    }
+
+    private boolean poolInactive() {
+        return this.internalPool == null || this.internalPool.isClosed();
+    }
+
+    public void addObjects(int count) throws Exception {
+        try {
+            for (int i = 0; i < count; i++) {
+                this.internalPool.addObject();
+            }
+        } catch (Exception e) {
+            throw new Exception("Error trying to add idle objects", e);
+        }
+    }
+}

apps/scholexplorer-api/src/main/java/eu/dnetlib/scholix/api/index/ScholixIndexManager.java

@@ -11,13 +11,14 @@ import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.tuple.ImmutablePair;
 import org.apache.commons.lang3.tuple.Pair;
 import org.apache.lucene.search.join.ScoreMode;
+import org.elasticsearch.client.RestHighLevelClient;
 import org.elasticsearch.index.query.BoolQueryBuilder;
 import org.elasticsearch.index.query.NestedQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.TermQueryBuilder;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.PageRequest;
-import org.springframework.data.elasticsearch.core.ElasticsearchOperations;
+import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
 import org.springframework.data.elasticsearch.core.SearchHit;
 import org.springframework.data.elasticsearch.core.SearchHits;
 import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
@@ -45,7 +46,7 @@ public class ScholixIndexManager {
      * The Elasticsearch template.
      */
     @Autowired
-    ElasticsearchOperations elasticsearchTemplate;
+    ElasticSearchPool connectionPool;
 
     /**
      * The My counter.
@@ -205,12 +206,13 @@ public class ScholixIndexManager {
                 .withPageable(PageRequest.of(page,10))
                 .build();
 
-        long tt = elasticsearchTemplate.count(finalQuery, Scholix.class, IndexCoordinates.of(elasticSearchProperties.getIndexName()));
+        RestHighLevelClient client = connectionPool.getResource();
-        System.out.println(tt);
+        ElasticsearchRestTemplate template = new ElasticsearchRestTemplate(client);
+        long tt = template.count(finalQuery, Scholix.class, IndexCoordinates.of(elasticSearchProperties.getIndexName()));
 
-        SearchHits<Scholix> scholixRes = elasticsearchTemplate.search(finalQuery, Scholix.class, IndexCoordinates.of(elasticSearchProperties.getIndexName()));
+        SearchHits<Scholix> scholixRes = template.search(finalQuery, Scholix.class, IndexCoordinates.of(elasticSearchProperties.getIndexName()));
 
-        System.out.println("SIZE OF HITS ->"+scholixRes.getSearchHits().size());
+        connectionPool.returnResource(client);
 
         return new ImmutablePair<>(tt,scholixRes.stream().map(SearchHit::getContent).collect(Collectors.toList()));
     }

pom.xml

@@ -142,6 +142,13 @@
 			<scope>test</scope>
 		</dependency>
 
+		<dependency>
+			<groupId>org.apache.commons</groupId>
+			<artifactId>commons-pool2</artifactId>
+			<version>2.11.1</version>
+		</dependency>
+
+
 	</dependencies>
 
 	<dependencyManagement>