better control over close-state of remote solr connections

source/net/yacy/cora/federate/solr/connector/CachedSolrConnector.java

@@ -74,6 +74,11 @@ public class CachedSolrConnector extends AbstractSolrConnector implements SolrCo
         if (this.solr != null) this.solr.commit(true);
     }
 
+    @Override
+    public boolean isClosed() {
+        return this.solr == null || this.solr.isClosed(); 
+    }
+    
     protected void finalize() throws Throwable {
         this.close();
     }

source/net/yacy/cora/federate/solr/connector/ConcurrentUpdateSolrConnector.java

@@ -291,6 +291,11 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
         return this.connector.getSegmentCount();
     }
 
+    @Override
+    public boolean isClosed() {
+        return this.connector == null || this.connector.isClosed(); 
+    }
+    
     @Override
     public void close() {
         ensureAliveDeletionHandler();
@@ -301,6 +306,8 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
         try {this.updateHandler.join();} catch (final InterruptedException e) {}
         this.connector.close();
         this.idCache.clear();
+        this.connector = null;
+        this.idCache = null;
     }
 
     @Override

source/net/yacy/cora/federate/solr/connector/EmbeddedSolrConnector.java

@@ -142,6 +142,11 @@ public class EmbeddedSolrConnector extends SolrServerConnector implements SolrCo
         return this.core.getSolrConfig();
     }
 
+    @Override
+    public boolean isClosed() {
+        return this.core == null || this.core.isClosed();
+    }
+    
     protected void finalize() throws Throwable {
         this.close();
     }

source/net/yacy/cora/federate/solr/connector/MirrorSolrConnector.java

@@ -121,10 +121,15 @@ public class MirrorSolrConnector extends AbstractSolrConnector implements SolrCo
         return Math.max(s0, s1);
     }
 
+    @Override
+    public boolean isClosed() {
+        return (this.solr0 == null || this.solr0.isClosed()) && (this.solr1 == null || this.solr1.isClosed());
+    }
+    
     @Override
     public synchronized void close() {
-        if (this.solr0 != null) this.solr0.close();
-        if (this.solr1 != null) this.solr1.close();
+        if (this.solr0 != null) {this.solr0.close(); this.solr0 = null;}
+        if (this.solr1 != null) {this.solr1.close(); this.solr1 = null;}
     }
 
     /**

source/net/yacy/cora/federate/solr/connector/SolrConnector.java

@@ -69,6 +69,12 @@ public interface SolrConnector extends Iterable<String> /* Iterable of document
      */
     public int getSegmentCount();
     
+    /**
+     * test if the connector is already closed
+     * @return true if the connector is closed
+     */
+    public boolean isClosed();
+    
     /**
      * close the server connection
      */

source/net/yacy/cora/federate/solr/connector/SolrServerConnector.java

@@ -121,12 +121,23 @@ public abstract class SolrServerConnector extends AbstractSolrConnector implemen
         }
     }
 
+    @Override
+    public boolean isClosed() {
+        return this.server == null; // we cannot now this exactly when server != null, because SolrServer does not provide a method to test the close status
+    }
 
     @Override
     public void close() {
         if (this.server == null) return;
         try {
-            if (this.server instanceof EmbeddedSolrServer) synchronized (this.server) {this.server.commit(true, true, false);}
+            if (this.server instanceof EmbeddedSolrServer) {
+                synchronized (this.server) {
+                    this.server.commit(true, true, false);
+                }
+            }
+            synchronized (this.server) {
+                this.server.shutdown(); // if the server is embedded, resources are freed, if it is a HttpSolrServer, only the httpclient is shut down, not the remote server
+            }
             this.server = null;
         } catch (final Throwable e) {
             ConcurrentLog.logException(e);

source/net/yacy/peers/Protocol.java

@@ -1040,8 +1040,11 @@ public final class Protocol {
             if (localsearch && !Switchboard.getSwitchboard().getConfigBool(SwitchboardConstants.DEBUG_SEARCH_REMOTE_SOLR_TESTLOCAL, false)) {
                 // search the local index
                 try {
-                    rsp[0] = event.getQuery().getSegment().fulltext().getDefaultConnector().getResponseByParams(solrQuery);
+                    SolrConnector sc = event.getQuery().getSegment().fulltext().getDefaultConnector();
+                    if (!sc.isClosed()) {
+                        rsp[0] = sc.getResponseByParams(solrQuery);
                         docList[0] = rsp[0].getResults();
+                    }
                 } catch (final Throwable e) {
                     Network.log.info("SEARCH failed (solr), localpeer (" + e.getMessage() + ")", e);
                     return -1;
@@ -1061,7 +1064,7 @@ public final class Protocol {
                                 RemoteInstance instance = new RemoteInstance("http://" + address, null, "solr", solrtimeout); // this is a 'patch configuration' which considers 'solr' as default collection
                                 try {
                                     SolrConnector solrConnector = new RemoteSolrConnector(instance, myseed ? true : target.getVersion() >= 1.63, "solr");
-                                    try {
+                                    if (!solrConnector.isClosed()) try {
                                         rsp[0] = solrConnector.getResponseByParams(solrQuery);
                                         docList[0] = rsp[0].getResults();
                                     } catch (Throwable e) {} finally {