HCOLL-81 extend support for mapForkey to all maps.

src/main/java/net/openhft/chronicle/map/ChronicleMap.java

@@ -166,7 +166,7 @@ public interface ChronicleMap<K, V> extends ConcurrentMap<K, V>, ChronicleHash {
      * defaultValueProvider.}
      *
      * <p>If the {@code ChronicleMap} is off-heap updatable, i. e. created via {@link
-     * ChronicleMapBuilder} builder (values are {@link Byteable}), there is one more option of
+     * ChronicleMapBuilder} builder (values are {@tlink Byteable}), there is one more option of
      * what to do if the key is absent in the map, see {@link ChronicleMapBuilder#prepareValueBytesOnAcquire(PrepareValueBytes)}.
      * By default, value bytes are just zeroed out, no default value, either provided for key or constant, is
      * put for the absent key.
@@ -182,5 +182,16 @@ public interface ChronicleMap<K, V> extends ConcurrentMap<K, V>, ChronicleHash {
     @NotNull
     WriteContext<K, V> acquireUsingLocked(@NotNull K key, @NotNull V usingValue);
 
+    /**
+     * Apply a mapping to the value returned by a key and return a result.
+     * A read lock is assumed.
+     *
+     * @param key      to apply the mapping to
+     * @param function to calculate a result
+     * @param <R>      return type.
+     * @return the result of the function.
+     */
+    <R> R mapForKey(K key, @NotNull Function<? super V, R> function);
+
 }
 

src/main/java/net/openhft/chronicle/map/StatelessChronicleMap.java

@@ -458,7 +458,7 @@ class StatelessChronicleMap<K, V> implements ChronicleMap<K, V>, Closeable {
     }
 
 
-    public synchronized <R> R mapForKey(K key, @NotNull Function<V, R> function) {
+    public synchronized <R> R mapForKey(K key, @NotNull Function<? super V, R> function) {
 
         final ThreadLocalCopies local = keyValueSerializer.threadLocalCopies();
         final long sizeLocation = writeEventAnSkip(MAP_FOR_KEY);
@@ -471,7 +471,7 @@ class StatelessChronicleMap<K, V> implements ChronicleMap<K, V>, Closeable {
     }
 
 
-    private <R> void writeObject(@NotNull Function<V, R> function) {
+    private <R> void writeObject(@NotNull Object function) {
         long start = bytes.position();
         for (; ; ) {
             try {

src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java

@@ -34,8 +34,6 @@ import net.openhft.lang.model.constraints.Nullable;
 import net.openhft.lang.threadlocal.Provider;
 import net.openhft.lang.threadlocal.ThreadLocalCopies;
 import org.jetbrains.annotations.NotNull;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import java.io.File;
 import java.io.IOException;
@@ -56,9 +54,6 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, KI>,
         V, VW, MVW extends MetaBytesWriter<V, VW>> extends AbstractMap<K, V>
         implements ChronicleMap<K, V>, Serializable {
 
-
-    private static final Logger LOG = LoggerFactory.getLogger(VanillaChronicleMap.class);
-
     /**
      * Because DirectBitSet implementations couldn't find more than 64 continuous clear or set bits.
      */
@@ -372,6 +367,14 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, KI>,
         }
     }
 
+    @Override
+    public <R> R mapForKey(K key, @NotNull Function<? super V, R> function) {
+        try (Context<K, V> entry = lookupUsing(key, null,
+                LockType.READ_LOCK, false)) {
+            return function.apply(entry.value());
+        }
+    }
+
     @NotNull
     @Override
     public WriteContext<K, V> acquireUsingLocked(@NotNull K key, @NotNull V usingValue) {