feature: native copy-on-write support

src/main/java/com/keuin/kbackupfabric/backup/incremental/manager/IncrementalBackupStorageManager.java

@@ -6,13 +6,15 @@
 import com.keuin.kbackupfabric.backup.incremental.identifier.ObjectIdentifier;
 import com.keuin.kbackupfabric.util.FilesystemUtil;
 import com.keuin.kbackupfabric.util.PrintUtil;
+import com.keuin.kbackupfabric.util.cow.FileCopier;
+import com.keuin.kbackupfabric.util.cow.FileCowCopier;
+import com.keuin.kbackupfabric.util.cow.FileEagerCopier;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
-import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.*;
 import java.util.logging.Logger;
@@ -27,9 +29,21 @@ public class IncrementalBackupStorageManager {
     private final Logger logger = Logger.getLogger(IncrementalBackupStorageManager.class.getName());
     private final Path backupStorageBase;
     private final Logger LOGGER = Logger.getLogger(IncrementalBackupStorageManager.class.getName());
+    private FileCopier copier = null;
 
     public IncrementalBackupStorageManager(Path backupStorageBase) {
         this.backupStorageBase = backupStorageBase;
+        try {
+            this.copier = FileCowCopier.getInstance();
+        } catch (Exception | UnsatisfiedLinkError ex) {
+            PrintUtil.error("Failed to initialize kbackup-cow: " + ex + ex.getMessage());
+            this.copier = new FileEagerCopier();
+        }
+        if (this.copier.isCow()) {
+            PrintUtil.info("Copy-on-write is enabled");
+        } else {
+            PrintUtil.info("Copy-on-write is disabled");
+        }
     }
 
     /**
@@ -85,7 +99,7 @@ IncCopyResult addObjectCollection(ObjectCollection2 collection, File collectionB
             if (!contains(entry.getValue())) {
                 // element does not exist. copy.
                 logger.fine("Copy new file `" + copySourceFile.getName() + "`.");
-                Files.copy(copySourceFile.toPath(), copyDestination.toPath());
+                copier.copy(copyDestination.getAbsolutePath(), copySourceFile.getAbsolutePath());
                 copyCount = copyCount.addWith(new IncCopyResult(1, 1, fileBytes, fileBytes));
             } else {
                 // element exists (file reused). Just update the stat info
@@ -198,7 +212,7 @@ public int restoreObjectCollection(ObjectCollection2 collection, File collection
                 }
             }
 
-            Files.copy(copySource.toPath(), copyTarget.toPath());
+            copier.copy(copyTarget.getAbsolutePath(), copySource.getAbsolutePath());
             ++copyCount;
         }
 

src/main/java/com/keuin/kbackupfabric/operation/backup/method/ConfiguredIncrementalBackupMethod.java

@@ -46,7 +46,7 @@ public ConfiguredIncrementalBackupMethod(String backupIndexFileName, String leve
     @Override
     public IncrementalBackupFeedback backup() {
         final int hashFactoryThreads = ThreadingUtil.getRecommendedThreadCount(); // how many threads do we use to generate the hash tree
-        LOGGER.info("Threads: " + hashFactoryThreads);
+        PrintUtil.info("Threads: " + hashFactoryThreads);
 
         // needed in abort progress
         File levelPathFile = new File(levelPath);
@@ -99,6 +99,7 @@ public IncrementalBackupFeedback backup() {
             PrintUtil.info("Incremental backup finished.");
             feedback = new IncrementalBackupFeedback(true, copyResult);
         } catch (IOException e) {
+            PrintUtil.error("Incremental backup failed: " + e + e.getMessage());
             feedback = new IncrementalBackupFeedback(e);
         }
 

src/main/java/com/keuin/kbackupfabric/util/cow/FileCopier.java

@@ -0,0 +1,9 @@
+package com.keuin.kbackupfabric.util.cow;
+
+import java.io.IOException;
+
+public interface FileCopier {
+    void copy(String dst, String src) throws IOException;
+
+    boolean isCow();
+}

src/main/java/com/keuin/kbackupfabric/util/cow/FileCowCopier.java

@@ -0,0 +1,41 @@
+package com.keuin.kbackupfabric.util.cow;
+
+import com.keuin.kbackupfabric.util.PrintUtil;
+
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public final class FileCowCopier {
+    private static final AtomicBoolean initialized = new AtomicBoolean(false);
+
+    static {
+        try {
+            System.loadLibrary("kbackup_cow");
+        } catch (SecurityException | UnsatisfiedLinkError ignored) {
+        }
+    }
+
+    public static native void init();
+
+    public static native void copy(String dst, String src) throws IOException;
+
+    public static native String getVersion();
+
+    public static FileCopier getInstance() {
+        if (initialized.compareAndSet(false, true)) {
+            FileCowCopier.init();
+            PrintUtil.info("kbackup-cow version: " + FileCowCopier.getVersion());
+        }
+        return new FileCopier() {
+            @Override
+            public void copy(String dst, String src) throws IOException {
+                FileCowCopier.copy(dst, src);
+            }
+
+            @Override
+            public boolean isCow() {
+                return true;
+            }
+        };
+    }
+}

src/main/java/com/keuin/kbackupfabric/util/cow/FileEagerCopier.java

@@ -0,0 +1,17 @@
+package com.keuin.kbackupfabric.util.cow;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
+public class FileEagerCopier implements FileCopier {
+    @Override
+    public void copy(String dst, String src) throws IOException {
+        Files.copy(Paths.get(src), Paths.get(dst));
+    }
+
+    @Override
+    public boolean isCow() {
+        return false;
+    }
+}