Initial commit for FilePerMap implementation.

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

@@ -13,17 +13,26 @@ import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 /**
- *
+ * A {@link Map} implementation that stores each entry as a file in a
+ * directory. The <code>key</> is the file name and the <code>value</>
+ * is the contents of the file. This map will only handle <code>String</>'s.
+ * <p>
+ * The class is effectively an abstraction over a directory in the file system.
+ * Therefore when the underlying files are changed an event will be fired to those
+ * registered for notifications.
+ * Since every write to this map will cause a change to underlying
+ * file system the event will distinguish between a programmatic event
+ * (i.e one caused my the actions of the map itself) and an event that
+ * has been triggered as a direct result of a file being manipulated outside
+ * this class.
  */
 public class FilePerKeyMap implements Map<String, String> {
-    private final String dir;
     private final Path dirPath;
     private final Map<File, Long> lastModifiedByProgram = new ConcurrentHashMap<>();
     private final List<Consumer<FPMEvent>> listeners = new ArrayList<>();
     private final FPMWatcher fileFpmWatcher = new FPMWatcher();
 
     public FilePerKeyMap(String dir){
-        this.dir = dir;
         this.dirPath = Paths.get(dir);
         try {
             Files.createDirectories(dirPath);
@@ -59,7 +68,6 @@ public class FilePerKeyMap implements Map<String, String> {
 
     @Override
     public boolean containsKey(Object key) {
-
         return getFiles().anyMatch(p->p.getFileName().toString().equals(key));
     }
 
@@ -87,10 +95,9 @@ public class FilePerKeyMap implements Map<String, String> {
     public String remove(Object key) {
         String existing = get(key);
         if(existing != null){
-            deleteFile(Paths.get(dir, (String)key));
+            deleteFile(dirPath.resolve((String) key));
         }
         return existing;
-
     }
 
     @Override
@@ -132,7 +139,7 @@ public class FilePerKeyMap implements Map<String, String> {
         try {
             return Files.walk(dirPath).filter(p -> !Files.isDirectory(p));
         } catch (IOException e) {
-            throw new AssertionError(e);
+            throw new RuntimeException(e);
         }
     }
 
@@ -142,7 +149,7 @@ public class FilePerKeyMap implements Map<String, String> {
             try {
                 existingValue = Files.readAllLines(path).stream().collect(Collectors.joining());
             } catch (IOException e) {
-                throw new AssertionError(e);
+                throw new RuntimeException(e);
             }
         }
         return existingValue;
@@ -208,7 +215,6 @@ public class FilePerKeyMap implements Map<String, String> {
 
             if (key != null ? !key.equals(fpmEntry.key) : fpmEntry.key != null) return false;
             return !(value != null ? !value.equals(fpmEntry.value) : fpmEntry.value != null);
-
         }
 
         @Override