core: Cache NFS file handle bytes in Inode

Currently, we regularly convert between Inode and NFS file handles, but
keep regenerating the byte representation, even if it is unchanged.

Cache the byte representation whenever possible, returning clones of the
byte array upon calling Inode#toNfsHandle instead of using ByteBuffer.

Related: #149
Signed-off-by: Christian Kohlschütter <[email protected]>

Author: kohlschuetter

core/src/main/java/org/dcache/nfs/vfs/Inode.java

@@ -51,6 +51,7 @@ public class Inode {
     private final int exportIdx;
     private final int type;
     private final byte[] fs_opaque;
+    private final byte[] nfsHandle;
 
     @Deprecated(forRemoval = true)
     public Inode(FileHandle fh) {
@@ -73,6 +74,8 @@ public Inode(int generation, int exportIdx, int type, byte[] fs_opaque) {
         this.exportIdx = exportIdx;
         this.type = type;
         this.fs_opaque = fs_opaque;
+
+        this.nfsHandle = buildNfsHandle();
     }
 
     /**
@@ -105,6 +108,7 @@ public Inode(byte[] bytes) {
             fs_opaque = new byte[olen];
             b.get(fs_opaque);
 
+            this.nfsHandle = bytes.clone();
         } else if (arrayEquals(bytes, FH_V0_REG, FH_V0_REG.length)
                 || arrayEquals(bytes, FH_V0_PFS, FH_V0_PFS.length)) {
             magic = MAGIC;
@@ -125,6 +129,8 @@ public Inode(byte[] bytes) {
                 exportIdx = -1;
                 fs_opaque = bytes;
             }
+
+            this.nfsHandle = buildNfsHandle();
         } else {
             throw new IllegalArgumentException("Unsupported version: " + geussVersion);
         }
@@ -157,7 +163,7 @@ protected byte[] getFsOpaque() {
 
     @Override
     public String toString() {
-        return BaseEncoding.base16().lowerCase().encode(this.toNfsHandle());
+        return BaseEncoding.base16().lowerCase().encode(nfsHandle);
     }
 
     private static boolean arrayEquals(byte[] a1, byte[] a2, int len) {
@@ -184,6 +190,10 @@ public byte[] getFileId() {
     }
 
     public byte[] toNfsHandle() {
+        return nfsHandle.clone();
+    }
+
+    private byte[] buildNfsHandle() {
         int len = fs_opaque.length + MIN_LEN;
         byte[] bytes = new byte[len];
         ByteBuffer b = ByteBuffer.wrap(bytes);
@@ -196,11 +206,11 @@ public byte[] toNfsHandle() {
         b.put((byte) fs_opaque.length);
         b.put(fs_opaque);
         return bytes;
-     }
+    }
 
     @Override
     public int hashCode() {
-        return Arrays.hashCode(toNfsHandle());
+        return Arrays.hashCode(nfsHandle);
     }
 
     @Override
@@ -212,7 +222,7 @@ public boolean equals(Object obj) {
             return false;
         }
         final Inode other = (Inode) obj;
-        return Arrays.equals(toNfsHandle(), other.toNfsHandle());
+        return Arrays.equals(nfsHandle, other.nfsHandle);
     }
 
     public boolean isPseudoInode() {