feature: configurable CoW incremental backup

3 files changed, 70 insertions, 0 deletions

diff --git a/src/main/java/com/keuin/kbackupfabric/util/cow/FileCopier.java b/src/main/java/com/keuin/kbackupfabric/util/cow/FileCopier.java
new file mode 100644
index 0000000..eb21af7
--- /dev/null
+++ b/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();
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/util/cow/FileCowCopier.java b/src/main/java/com/keuin/kbackupfabric/util/cow/FileCowCopier.java
new file mode 100644
index 0000000..e5819de
--- /dev/null
+++ b/src/main/java/com/keuin/kbackupfabric/util/cow/FileCowCopier.java
@@ -0,0 +1,44 @@
+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());
+        }
+        // call a native method to ensure the dynamic library is correctly loaded, JVM will throw if failed
+        // so the outside fallback logic could work
+        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;
+            }
+        };
+    }
+}
diff --git a/src/main/java/com/keuin/kbackupfabric/util/cow/FileEagerCopier.java b/src/main/java/com/keuin/kbackupfabric/util/cow/FileEagerCopier.java
new file mode 100644
index 0000000..0f12374
--- /dev/null
+++ b/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;
+    }
+}