Ensure the chunk size is a multiple of the alignment, closed https://github.com/OpenHFT/Chronicle-Map/issues/169

src/main/java/net/openhft/chronicle/hash/impl/VanillaChronicleHash.java

@@ -708,8 +708,8 @@ public abstract class VanillaChronicleHash<K,
 
         // int division is MUCH faster than long on Intel CPUs
         if (sizeInBytes <= Integer.MAX_VALUE)
-            return (((int) sizeInBytes) / (int) chunkSize) + 1;
-        return (int) (sizeInBytes / chunkSize) + 1;
+            return (int) (sizeInBytes + chunkSize - 1) / (int) chunkSize;
+        return Math.toIntExact((sizeInBytes + chunkSize - 1) / chunkSize);
     }
 
     public final int size() {

src/main/java/net/openhft/chronicle/hash/serialization/impl/ByteArrayDataAccess.java

@@ -102,4 +102,9 @@ public class ByteArrayDataAccess extends AbstractData<byte[]> implements DataAcc
         // no fields to read
         initTransients();
     }
+
+    @Override
+    public String toString() {
+        return new String(array, 0, 0, array.length);
+    }
 }

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

@@ -730,6 +730,8 @@ public final class ChronicleMapBuilder<K, V> implements
         }
         if (actualChunkSize <= 0)
             throw new IllegalArgumentException("Chunk size must be positive");
+        if (alignment > 0 && actualChunkSize % alignment != 0)
+            throw new IllegalArgumentException("The chunk size (" + actualChunkSize + ") must be a multiple of the alignment (" + alignment + ")");
         this.actualChunkSize = actualChunkSize;
         return this;
     }
@@ -928,16 +930,25 @@ public final class ChronicleMapBuilder<K, V> implements
         }
         if (Jvm.isArm() && alignment < 8)
             return this;
+        validateAlignment(actualChunkSize, actualChunkSize, alignment);
+
         this.alignment = alignment;
         return this;
     }
 
+    public void validateAlignment(int ifSet, int actualChunkSize, int alignment) {
+        if (ifSet > 0 && actualChunkSize % alignment != 0)
+            throw new IllegalArgumentException("The chunk size (" + actualChunkSize + ") must be a multiple of the alignment (" + alignment + ")");
+    }
+
     int valueAlignment() {
         if (alignment != UNDEFINED_ALIGNMENT_CONFIG)
             return alignment;
         try {
             if (Values.isValueInterfaceOrImplClass(valueBuilder.tClass)) {
-                return ValueModel.acquire(valueBuilder.tClass).recommendedOffsetAlignment();
+                int alignment = ValueModel.acquire(valueBuilder.tClass).recommendedOffsetAlignment();
+                validateAlignment(alignment, actualChunkSize, alignment);
+                return alignment;
             } else {
                 return NO_ALIGNMENT;
             }