Lock ordering made right

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

@@ -0,0 +1,37 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.openhft.chronicle.hash;
+
+import net.openhft.chronicle.hash.locks.InterProcessReadWriteUpdateLock;
+
+/**
+ * {@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();
+}