WIP: Working toward a solution that can cache result sets and/or transformed entity instances when annotated with @Cacheable in the Session cache.

src/main/java/net/helenus/core/SessionInitializer.java

@@ -220,7 +220,6 @@ public final class SessionInitializer extends AbstractSessionOperations {
   }
 
   public void singleton() {
-
     Helenus.setSession(get());
   }
 

src/main/java/net/helenus/core/operation/AbstractOperation.java

@@ -20,17 +20,17 @@ import java.util.concurrent.CompletableFuture;
 import net.helenus.core.AbstractSessionOperations;
 
 public abstract class AbstractOperation<E, O extends AbstractOperation<E, O>>
-    extends AbstractStatementOperation<E, O> implements Transformational<E> {
+    extends AbstractStatementOperation<E, O> implements OperationsDelegate<E> {
 
   public abstract E transform(ResultSet resultSet);
 
+  protected CacheManager getCacheManager() { return null; }
+
   public boolean cacheable() {
     return false;
   }
 
-  public String getCacheKey() {
-    return "";
-  }
+  public CacheKey getCacheKey() { return null; }
 
   public AbstractOperation(AbstractSessionOperations sessionOperations) {
     super(sessionOperations);

src/main/java/net/helenus/core/operation/AbstractOptionalOperation.java

@@ -25,7 +25,7 @@ import java.util.concurrent.CompletableFuture;
 import net.helenus.core.AbstractSessionOperations;
 
 public abstract class AbstractOptionalOperation<E, O extends AbstractOptionalOperation<E, O>>
-    extends AbstractStatementOperation<E, O> implements Transformational<Optional<E>> {
+    extends AbstractStatementOperation<E, O> implements OperationsDelegate<Optional<E>> {
 
   public AbstractOptionalOperation(AbstractSessionOperations sessionOperations) {
     super(sessionOperations);
@@ -33,6 +33,10 @@ public abstract class AbstractOptionalOperation<E, O extends AbstractOptionalOpe
 
   public abstract Optional<E> transform(ResultSet resultSet);
 
+  protected CacheManager getCacheManager() { return null; }
+
+  public CacheKey getCacheKey() { return null; }
+
   public PreparedOptionalOperation<E> prepare() {
     return new PreparedOptionalOperation<E>(prepareStatement(), this);
   }

src/main/java/net/helenus/core/operation/AbstractStreamOperation.java

@@ -25,7 +25,7 @@ import java.util.stream.Stream;
 import net.helenus.core.AbstractSessionOperations;
 
 public abstract class AbstractStreamOperation<E, O extends AbstractStreamOperation<E, O>>
-    extends AbstractStatementOperation<E, O> implements Transformational<Stream<E>> {
+    extends AbstractStatementOperation<E, O> implements OperationsDelegate<Stream<E>> {
 
   public AbstractStreamOperation(AbstractSessionOperations sessionOperations) {
     super(sessionOperations);
@@ -33,6 +33,10 @@ public abstract class AbstractStreamOperation<E, O extends AbstractStreamOperati
 
   public abstract Stream<E> transform(ResultSet resultSet);
 
+  protected CacheManager getCacheManager() { return null; }
+
+  public CacheKey getCacheKey() { return null; }
+
   public PreparedStreamOperation<E> prepare() {
     return new PreparedStreamOperation<E>(prepareStatement(), this);
   }
@@ -51,11 +55,11 @@ public abstract class AbstractStreamOperation<E, O extends AbstractStreamOperati
 
   public Stream<E> sync() {
     return Executioner.INSTANCE.<Stream<E>>sync(
-        sessionOps, options(buildStatement()), traceContext, this, showValues);
+        sessionOps, options(buildStatement()), getCacheManager(), traceContext, this, showValues);
   }
 
   public CompletableFuture<Stream<E>> async() {
     return Executioner.INSTANCE.<Stream<E>>async(
-        sessionOps, options(buildStatement()), traceContext, this, showValues);
+        sessionOps, options(buildStatement()), getCacheManager(), traceContext, this, showValues);
   }
 }

src/main/java/net/helenus/core/operation/BoundOptionalOperation.java

@@ -38,6 +38,9 @@ public final class BoundOptionalOperation<E>
     return delegate.transform(resultSet);
   }
 
+  @Override
+  public CacheKey getCacheKey() { return delegate.getCacheKey(); }
+
   @Override
   public Statement buildStatement() {
     return boundStatement;

src/main/java/net/helenus/core/operation/BoundStreamOperation.java

@@ -25,19 +25,27 @@ public final class BoundStreamOperation<E>
 
   private final BoundStatement boundStatement;
   private final AbstractStreamOperation<E, ?> delegate;
+  private final CacheKey cacheKey;
 
   public BoundStreamOperation(
-      BoundStatement boundStatement, AbstractStreamOperation<E, ?> operation) {
+      BoundStatement boundStatement, CacheKey cacheKey, AbstractStreamOperation<E, ?> operation) {
     super(operation.sessionOps);
     this.boundStatement = boundStatement;
+    this.cacheKey = cacheKey;
     this.delegate = operation;
   }
 
+  @Override
+  protected CacheManager getCacheManager() { return delegate.getCacheManager(); }
+
   @Override
   public Stream<E> transform(ResultSet resultSet) {
     return delegate.transform(resultSet);
   }
 
+  @Override
+  public CacheKey getCacheKey() { return cacheKey; }
+
   @Override
   public Statement buildStatement() {
     return boundStatement;

src/main/java/net/helenus/core/operation/CacheKey.java

@@ -0,0 +1,30 @@
+package net.helenus.core.operation;
+
+public class CacheKey {
+
+    private String key;
+
+    CacheKey() {}
+
+    CacheKey(String key) { this.key = key; }
+
+    public void set(String key) { this.key = key; }
+
+    public String toString() { return key; }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+
+        CacheKey cacheKey = (CacheKey) o;
+
+        return key.equals(cacheKey.key);
+    }
+
+    @Override
+    public int hashCode() {
+        return key.hashCode();
+    }
+
+}

src/main/java/net/helenus/core/operation/CacheManager.java

@@ -0,0 +1,49 @@
+package net.helenus.core.operation;
+
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.core.ResultSetFuture;
+import com.datastax.driver.core.Statement;
+import net.helenus.mapping.HelenusEntity;
+
+import java.util.concurrent.ExecutionException;
+
+
+public abstract class CacheManager {
+    public enum Type { FETCH, MUTATE }
+
+    private static CacheManager sessionFetch = new SessionCacheManager(Type.FETCH);
+
+    protected CacheManager.Type type;
+
+
+    public static CacheManager of(Type type, HelenusEntity entity) {
+        if (entity != null && entity.isCacheable()) {
+            return sessionFetch;
+        }
+        return null;
+    }
+
+    public CacheManager(Type type) {
+        this.type = type;
+    }
+
+    protected abstract ResultSet fetch(Statement statement, OperationsDelegate delegate, ResultSetFuture resultSetFuture)
+            throws InterruptedException, ExecutionException;
+    protected abstract ResultSet mutate(Statement statement, OperationsDelegate delegate, ResultSetFuture resultSetFuture)
+            throws InterruptedException, ExecutionException;
+
+    public ResultSet apply(Statement statement, OperationsDelegate delegate, ResultSetFuture futureResultSet)
+            throws InterruptedException, ExecutionException {
+        ResultSet resultSet = null;
+        switch (type) {
+            case FETCH:
+                 resultSet = fetch(statement, delegate, futureResultSet);
+                break;
+            case MUTATE:
+                resultSet = mutate(statement, delegate, futureResultSet);
+                break;
+        }
+        return resultSet;
+    }
+
+}

src/main/java/net/helenus/core/operation/Executioner.java

@@ -7,6 +7,7 @@ import com.datastax.driver.core.ResultSet;
 import com.datastax.driver.core.ResultSetFuture;
 import com.datastax.driver.core.Statement;
 import net.helenus.core.AbstractSessionOperations;
+import net.helenus.support.HelenusException;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
@@ -14,28 +15,48 @@ import java.util.concurrent.ExecutionException;
 public enum Executioner {
   INSTANCE;
 
-  <E> E sync(
-      AbstractSessionOperations session,
-      Statement statement,
-      TraceContext traceContext,
-      Transformational<E> delegate,
-      boolean showValues) {
+    <E> E sync(
+            AbstractSessionOperations session,
+            Statement statement,
+            TraceContext traceContext,
+            OperationsDelegate<E> delegate,
+            boolean showValues) {
+        return sync(session, statement, null, traceContext, delegate, showValues);
+    }
+
+    <E> E sync(
+            AbstractSessionOperations session,
+            Statement statement,
+            CacheManager cacheManager,
+            TraceContext traceContext,
+            OperationsDelegate<E> delegate,
+            boolean showValues) {
     try {
-      return this.<E>async(session, statement, traceContext, delegate, showValues).get();
+      return this.<E>async(session, statement, cacheManager, traceContext, delegate, showValues).get();
     } catch (InterruptedException | ExecutionException e) {
-      return null;
+        throw new HelenusException(e);
     }
   }
 
   public <E> CompletableFuture<E> async(
-      AbstractSessionOperations session,
-      Statement statement,
-      TraceContext traceContext,
-      Transformational<E> delegate,
-      boolean showValues) {
+            AbstractSessionOperations session,
+            Statement statement,
+            TraceContext traceContext,
+            OperationsDelegate<E> delegate,
+            boolean showValues) {
+        return async(session, statement, null, traceContext, delegate, showValues);
+  }
+
+  public <E> CompletableFuture<E> async(
+            AbstractSessionOperations session,
+            Statement statement,
+            CacheManager cacheManager,
+            TraceContext traceContext,
+            OperationsDelegate<E> delegate,
+            boolean showValues) {
     ResultSetFuture futureResultSet = session.executeAsync(statement, showValues);
 
-    return CompletableFuture.supplyAsync(
+    return CompletableFuture.<E>supplyAsync(
         () -> {
           Tracer tracer = session.getZipkinTracer();
           final Span span =
@@ -45,7 +66,8 @@ public enum Executioner {
               span.name("cassandra");
               span.start();
             }
-            ResultSet resultSet = futureResultSet.get(); // TODO: timeout
+            ResultSet resultSet = cacheManager != null ? cacheManager.apply(statement, delegate, futureResultSet) :
+                    futureResultSet.get();
             E result = delegate.transform(resultSet);
 
             return result;

src/main/java/net/helenus/core/operation/OperationsDelegate.java

@@ -2,6 +2,7 @@ package net.helenus.core.operation;
 
 import com.datastax.driver.core.ResultSet;
 
-public interface Transformational<E> {
+public interface OperationsDelegate<E> {
   E transform(ResultSet resultSet);
+  CacheKey getCacheKey();
 }

src/main/java/net/helenus/core/operation/PreparedStreamOperation.java

@@ -18,6 +18,8 @@ package net.helenus.core.operation;
 import com.datastax.driver.core.BoundStatement;
 import com.datastax.driver.core.PreparedStatement;
 
+import java.util.regex.Pattern;
+
 public final class PreparedStreamOperation<E> {
 
   private final PreparedStatement preparedStatement;
@@ -37,7 +39,10 @@ public final class PreparedStreamOperation<E> {
 
     BoundStatement boundStatement = preparedStatement.bind(params);
 
-    return new BoundStreamOperation<E>(boundStatement, operation);
+    String key = "use " + preparedStatement.getQueryKeyspace() + "; " + preparedStatement.getQueryString();
+    for (Object param : params) { key = key.replaceFirst(Pattern.quote("?"), param.toString()); }
+
+    return new BoundStreamOperation<E>(boundStatement, new CacheKey(key), operation);
   }
 
   @Override

src/main/java/net/helenus/core/operation/SelectFirstOperation.java

@@ -46,4 +46,5 @@ public final class SelectFirstOperation<E>
   public Optional<E> transform(ResultSet resultSet) {
     return src.transform(resultSet).findFirst();
   }
+
 }

src/main/java/net/helenus/core/operation/SelectOperation.java

@@ -46,27 +46,31 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
   protected Integer limit = null;
   protected boolean allowFiltering = false;
 
+  protected CacheManager cacheManager;
+
   public SelectOperation(AbstractSessionOperations sessionOperations) {
     super(sessionOperations);
 
     this.rowMapper =
-        new Function<Row, E>() {
+            new Function<Row, E>() {
 
-          @Override
-          public E apply(Row source) {
+              @Override
+              public E apply(Row source) {
 
-            ColumnValueProvider valueProvider = sessionOps.getValueProvider();
-            Object[] arr = new Object[props.size()];
+                ColumnValueProvider valueProvider = sessionOps.getValueProvider();
+                Object[] arr = new Object[props.size()];
 
-            int i = 0;
-            for (HelenusPropertyNode p : props) {
-              Object value = valueProvider.getColumnValue(source, -1, p.getProperty());
-              arr[i++] = value;
-            }
+                int i = 0;
+                for (HelenusPropertyNode p : props) {
+                  Object value = valueProvider.getColumnValue(source, -1, p.getProperty());
+                  arr[i++] = value;
+                }
 
-            return (E) Fun.ArrayTuple.of(arr);
-          }
-        };
+                return (E) Fun.ArrayTuple.of(arr);
+              }
+            };
+
+    this.cacheManager = CacheManager.of(CacheManager.Type.FETCH, null) ;
   }
 
   public SelectOperation(AbstractSessionOperations sessionOperations, HelenusEntity entity) {
@@ -74,35 +78,41 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
     super(sessionOperations);
 
     entity
-        .getOrderedProperties()
-        .stream()
-        .map(p -> new HelenusPropertyNode(p, Optional.empty()))
-        .forEach(p -> this.props.add(p));
+            .getOrderedProperties()
+            .stream()
+            .map(p -> new HelenusPropertyNode(p, Optional.empty()))
+            .forEach(p -> this.props.add(p));
+
+    this.cacheManager = CacheManager.of(CacheManager.Type.FETCH, entity) ;
   }
 
   public SelectOperation(
-      AbstractSessionOperations sessionOperations,
-      HelenusEntity entity,
-      Function<Row, E> rowMapper) {
+          AbstractSessionOperations sessionOperations,
+          HelenusEntity entity,
+          Function<Row, E> rowMapper) {
 
     super(sessionOperations);
     this.rowMapper = rowMapper;
 
     entity
-        .getOrderedProperties()
-        .stream()
-        .map(p -> new HelenusPropertyNode(p, Optional.empty()))
-        .forEach(p -> this.props.add(p));
+            .getOrderedProperties()
+            .stream()
+            .map(p -> new HelenusPropertyNode(p, Optional.empty()))
+            .forEach(p -> this.props.add(p));
+
+    this.cacheManager = CacheManager.of(CacheManager.Type.FETCH, entity) ;
   }
 
   public SelectOperation(
-      AbstractSessionOperations sessionOperations,
-      Function<Row, E> rowMapper,
-      HelenusPropertyNode... props) {
+          AbstractSessionOperations sessionOperations,
+          Function<Row, E> rowMapper,
+          HelenusPropertyNode... props) {
 
     super(sessionOperations);
     this.rowMapper = rowMapper;
     Collections.addAll(this.props, props);
+
+    this.cacheManager = CacheManager.of(CacheManager.Type.FETCH, null) ;
   }
 
   public CountOperation count() {
@@ -114,10 +124,10 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
         entity = prop.getEntity();
       } else if (entity != prop.getEntity()) {
         throw new HelenusMappingException(
-            "you can count records only from a single entity "
-                + entity.getMappingInterface()
-                + " or "
-                + prop.getEntity().getMappingInterface());
+                "you can count records only from a single entity "
+                        + entity.getMappingInterface()
+                        + " or "
+                        + prop.getEntity().getMappingInterface());
       }
     }
 
@@ -138,11 +148,11 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
     this.rowMapper = null;
 
     return new SelectTransformingOperation<R, E>(
-        this,
-        (r) -> {
-          Map<String, Object> map = new ValueProviderMap(r, sessionOps.getValueProvider(), entity);
-          return (R) Helenus.map(entityClass, map);
-        });
+            this,
+            (r) -> {
+              Map<String, Object> map = new ValueProviderMap(r, sessionOps.getValueProvider(), entity);
+              return (R) Helenus.map(entityClass, map);
+            });
   }
 
   public <R> SelectTransformingOperation<R, E> map(Function<E, R> fn) {
@@ -192,10 +202,10 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
         entity = prop.getEntity();
       } else if (entity != prop.getEntity()) {
         throw new HelenusMappingException(
-            "you can select columns only from a single entity "
-                + entity.getMappingInterface()
-                + " or "
-                + prop.getEntity().getMappingInterface());
+                "you can select columns only from a single entity "
+                        + entity.getMappingInterface()
+                        + " or "
+                        + prop.getEntity().getMappingInterface());
       }
     }
 
@@ -224,7 +234,7 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
 
     if (ifFilters != null && !ifFilters.isEmpty()) {
       logger.error(
-          "onlyIf conditions " + ifFilters + " would be ignored in the statement " + select);
+              "onlyIf conditions " + ifFilters + " would be ignored in the statement " + select);
     }
 
     if (allowFiltering) {
@@ -242,16 +252,20 @@ public final class SelectOperation<E> extends AbstractFilterStreamOperation<E, S
 
       return StreamSupport.stream(
               Spliterators.spliteratorUnknownSize(resultSet.iterator(), Spliterator.ORDERED), false)
-          .map(rowMapper);
+              .map(rowMapper);
     } else {
 
       return (Stream<E>)
-          StreamSupport.stream(
-              Spliterators.spliteratorUnknownSize(resultSet.iterator(), Spliterator.ORDERED),
-              false);
+              StreamSupport.stream(
+                      Spliterators.spliteratorUnknownSize(resultSet.iterator(), Spliterator.ORDERED),
+                      false);
     }
   }
 
+  protected CacheManager getCacheManager() {
+    return cacheManager;
+  }
+
   private List<Ordering> getOrCreateOrdering() {
     if (ordering == null) {
       ordering = new ArrayList<Ordering>();

src/main/java/net/helenus/core/operation/SelectTransformingOperation.java

@@ -44,4 +44,5 @@ public final class SelectTransformingOperation<R, E>
   public Stream<R> transform(ResultSet resultSet) {
     return src.transform(resultSet).map(fn);
   }
+
 }

src/main/java/net/helenus/core/operation/SessionCacheManager.java

@@ -0,0 +1,72 @@
+package net.helenus.core.operation;
+
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.core.ResultSetFuture;
+import com.datastax.driver.core.Statement;
+import com.google.common.cache.*;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+
+public class SessionCacheManager extends CacheManager {
+    final Logger logger = LoggerFactory.getLogger(getClass());
+
+    private Cache<String, ResultSet> cache;
+
+    SessionCacheManager(CacheManager.Type type) {
+        super(type);
+
+        RemovalListener<String, ResultSet> listener;
+        listener = new RemovalListener<String, ResultSet>() {
+            @Override
+            public void onRemoval(RemovalNotification<String, ResultSet> n){
+                if (n.wasEvicted()) {
+                    String cause = n.getCause().name();
+                    logger.info(cause);
+                }
+            }
+        };
+
+        cache = CacheBuilder.newBuilder()
+                .maximumSize(10_000)
+                .expireAfterAccess(20, TimeUnit.MINUTES)
+                .weakKeys()
+                .softValues()
+                .removalListener(listener)
+                .build();
+    }
+
+    protected ResultSet fetch(Statement statement, OperationsDelegate delegate, ResultSetFuture resultSetFuture)
+            throws InterruptedException, ExecutionException {
+        CacheKey key = delegate.getCacheKey();
+        final String cacheKey = key == null ? statement.toString() : key.toString();
+        ResultSet resultSet = null;
+        if (cacheKey == null) {
+            resultSet = resultSetFuture.get();
+        } else {
+            resultSet = cache.getIfPresent(cacheKey);
+            if (resultSet == null) {
+                resultSet = resultSetFuture.get();
+                if (resultSet != null) {
+                    cache.put(cacheKey, resultSet);
+                }
+            }
+        }
+        return resultSet;
+    }
+
+    protected ResultSet mutate(Statement statement, OperationsDelegate delegate, ResultSetFuture resultSetFuture)
+            throws InterruptedException, ExecutionException {
+        CacheKey key = delegate.getCacheKey();
+        final String cacheKey = key == null ? statement.toString() : key.toString();
+        ResultSet resultSet = resultSetFuture.get();
+        if (cacheKey != null && resultSet != null) {
+            cache.put(cacheKey, resultSet);
+        }
+        return resultSet;
+    }
+
+}

src/test/java/net/helenus/test/integration/core/prepared/Car.java

@@ -16,10 +16,13 @@
 package net.helenus.test.integration.core.prepared;
 
 import java.math.BigDecimal;
+
+import net.helenus.core.annotation.Cacheable;
 import net.helenus.mapping.annotation.PartitionKey;
 import net.helenus.mapping.annotation.Table;
 
 @Table("cars")
+@Cacheable
 public interface Car {
 
   @PartitionKey(ordinal = 0)

src/test/java/net/helenus/test/integration/core/simple/User.java

@@ -15,11 +15,13 @@
  */
 package net.helenus.test.integration.core.simple;
 
+import net.helenus.core.annotation.Cacheable;
 import net.helenus.mapping.annotation.Column;
 import net.helenus.mapping.annotation.PartitionKey;
 import net.helenus.mapping.annotation.Table;
 
 @Table("simple_users")
+@Cacheable
 public interface User {
 
   @PartitionKey