Lock ordering made right

src/main/java/net/openhft/chronicle/hash/HashQueryContext.java

@@ -7,6 +7,7 @@ import net.openhft.chronicle.map.MapMethods;
 import net.openhft.chronicle.map.MapQueryContext;
 import net.openhft.chronicle.set.SetEntryOperations;
 import net.openhft.chronicle.set.SetQueryContext;
+import org.jetbrains.annotations.Nullable;
 
 /**
  * Context of {@link ChronicleHash} operations with <i>individual keys</i>.
@@ -137,7 +138,17 @@ import net.openhft.chronicle.set.SetQueryContext;
  * @param <K> the hash key type
  * @see ChronicleHash#queryContext(Object)
  */
-public interface HashQueryContext<K> extends HashContext<K>, InterProcessReadWriteUpdateLock {
+public interface HashQueryContext<K> extends HashContext<K>, SegmentLock {
+
+    /**
+     * Returns the index of the accessed segment, where the queried key is located (or to which
+     * the key is going to be put).
+     *
+     * <p>This index might also be used as the {@code InterProcessReadWriteUpdateLock} identifier,
+     * because {@code ChronicleHashes} has per-segment locks.
+     */
+    @Override
+    int segmentIndex();
 
     /**
      * Returns the queried key as a {@code Data}.
@@ -160,5 +171,6 @@ public interface HashQueryContext<K> extends HashContext<K>, InterProcessReadWri
      * @implNote Might acquire {@link #readLock} before searching for the key, if the context
      * is not locked yet.
      */
+    @Nullable
     HashAbsentEntry<K> absentEntry();
 }

src/main/java/net/openhft/chronicle/hash/SegmentLock.java

@@ -1,5 +1,7 @@
 /*
- * Copyright 2014 Higher Frequency Trading http://www.higherfrequencytrading.com
+ * Copyright 2015 Higher Frequency Trading
+ *
+ * http://www.higherfrequencytrading.com
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,11 +19,19 @@
 package net.openhft.chronicle.hash;
 
 import net.openhft.chronicle.hash.locks.InterProcessReadWriteUpdateLock;
-import org.jetbrains.annotations.NotNull;
 
-public interface Segment {
-    long index();
-
-    @NotNull
-    InterProcessReadWriteUpdateLock lock();
+/**
+ * {@link InterProcessReadWriteUpdateLock} of a segment in {@code ChronicleHash}.
+ *
+ * <p>In Chronicle-Map off-heap design, locks (and concurrency) are per-segment.
+ *
+ * @see ChronicleHashBuilder#minSegments(int)
+ * @see ChronicleHashBuilder#actualSegments(int)
+ */
+public interface SegmentLock extends InterProcessReadWriteUpdateLock {
+    
+    /**
+     * Returns the index of the accessed segment.
+     */
+    int segmentIndex();
 }

src/main/java/net/openhft/chronicle/hash/impl/stage/entry/SegmentStages.java

@@ -18,6 +18,7 @@
 
 package net.openhft.chronicle.hash.impl.stage.entry;
 
+import net.openhft.chronicle.hash.SegmentLock;
 import net.openhft.chronicle.hash.impl.BigSegmentHeader;
 import net.openhft.chronicle.hash.impl.LocalLockState;
 import net.openhft.chronicle.hash.impl.SegmentHeader;
@@ -38,7 +39,7 @@ import org.jetbrains.annotations.NotNull;
 import static net.openhft.chronicle.hash.impl.LocalLockState.UNLOCKED;
 
 @Staged
-public abstract class SegmentStages implements InterProcessReadWriteUpdateLock {
+public abstract class SegmentStages implements SegmentLock {
 
     @StageRef Chaining chaining;
     @StageRef public VanillaChronicleHashHolder<?, ?, ?> hh;
@@ -48,7 +49,6 @@ public abstract class SegmentStages implements InterProcessReadWriteUpdateLock {
     
     public void initTheSegmentIndex(int segmentIndex) {
         this.segmentIndex = segmentIndex;
-        
     }
 
     // "SegHeader" because stage-generator doesn't support stage names - one is a prefix of another

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

@@ -27,8 +27,6 @@ import org.jetbrains.annotations.Nullable;
  * (like during {@code get()}, {@code put()}, etc., opposed to <i>bulk</i> operations).
  * This is the main context type of {@link MapMethods} and {@link MapRemoteOperations}.
  *
- *
- * 
  * @param <K> the map key type
  * @param <V> the map value type
  * @param <R> the return type of {@link MapEntryOperations} specialized for the queried map