persistence: Implement RollingBackups

persistence/src/main/java/bisq/persistence/RollingBackupCreationFailedException.java

@@ -0,0 +1,24 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.persistence;
+
+public class RollingBackupCreationFailedException extends RuntimeException {
+    public RollingBackupCreationFailedException(String message) {
+        super(message);
+    }
+}

persistence/src/main/java/bisq/persistence/RollingBackups.java

@@ -0,0 +1,69 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.persistence;
+
+import java.io.File;
+
+public class RollingBackups {
+    private final File baseFile;
+    private final int numberOfBackups;
+    private final File parentDirFile;
+    private final String baseFileName;
+
+    public RollingBackups(File baseFile, int numberOfBackups) {
+        if (numberOfBackups < 1) {
+            throw new IllegalArgumentException("Number of backup is " + numberOfBackups);
+        }
+
+        this.baseFile = baseFile;
+        this.numberOfBackups = numberOfBackups;
+        parentDirFile = baseFile.getParentFile();
+        baseFileName = baseFile.getName();
+    }
+
+    public void rollBackups() {
+        for (int i = numberOfBackups - 2; i >= 0; i--) {
+            File originalFile = new File(parentDirFile, baseFileName + "_" + i);
+            File backupFile = new File(parentDirFile, baseFileName + "_" + (i + 1));
+            renameFile(originalFile, backupFile);
+        }
+
+        File backupFile = new File(parentDirFile, baseFileName + "_0");
+        renameFile(baseFile, backupFile);
+    }
+
+    private void renameFile(File originalFile, File newFile) {
+        if (!originalFile.exists()) {
+            return;
+        }
+
+        if (newFile.exists()) {
+            boolean isSuccess = newFile.delete();
+            if (!isSuccess) {
+                throw new RollingBackupCreationFailedException("Couldn't delete " + newFile.getAbsolutePath() +
+                        " before replacing it.");
+            }
+        }
+
+        boolean isSuccess = originalFile.renameTo(newFile);
+        if (!isSuccess) {
+            throw new RollingBackupCreationFailedException("Couldn't rename " + originalFile.getAbsolutePath() + " to "
+                    + newFile.getAbsolutePath());
+        }
+    }
+}

persistence/src/test/java/bisq/persistence/RollingBackupsTests.java

@@ -0,0 +1,179 @@
+/*
+ * This file is part of Bisq.
+ *
+ * Bisq is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Bisq is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Bisq. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package bisq.persistence;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import static bisq.persistence.DirectoryHasNChildren.hasNChildren;
+import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class RollingBackupsTests {
+    private Path baseFilePath;
+
+    @BeforeEach
+    void setup(@TempDir Path tempDir) {
+        baseFilePath = tempDir.resolve("file");
+    }
+
+    @Test
+    void noBackup(@TempDir Path tempDir) {
+        File file = new File(tempDir.toFile(), "file");
+        assertThrows(IllegalArgumentException.class, () -> new RollingBackups(file, 0));
+    }
+
+    @Test
+    void firstBackup(@TempDir Path tempDir) throws IOException {
+        Files.writeString(baseFilePath, "ABC");
+        assertThat(tempDir, hasNChildren(1));
+
+        RollingBackups rollingBackups = new RollingBackups(baseFilePath.toFile(), 1);
+        rollingBackups.rollBackups();
+
+        assertThat(tempDir, hasNChildren(1));
+
+        File backupFile = tempDir.resolve("file_0").toFile();
+        String backupFileContent = Files.readString(backupFile.toPath());
+        assertThat(backupFileContent, is("ABC"));
+    }
+
+    @Test
+    void oneBackupWithExistingFiles(@TempDir Path tempDir) throws IOException {
+        Files.writeString(baseFilePath, "NEW_CONTENT");
+
+        Path backupPath = tempDir.resolve("file_0");
+        Files.writeString(backupPath, "OLD_CONTENT");
+
+        assertThat(tempDir, hasNChildren(2));
+
+        RollingBackups rollingBackups = new RollingBackups(baseFilePath.toFile(), 1);
+        rollingBackups.rollBackups();
+
+        assertThat(tempDir, hasNChildren(1));
+        String backupFileContent = Files.readString(backupPath);
+        assertThat(backupFileContent, is("NEW_CONTENT"));
+    }
+
+    @Test
+    void threeBackupsFirstBackup(@TempDir Path tempDir) throws IOException {
+        Files.writeString(baseFilePath, "NEW_CONTENT");
+        assertThat(tempDir, hasNChildren(1));
+
+        RollingBackups rollingBackups = new RollingBackups(baseFilePath.toFile(), 3);
+        rollingBackups.rollBackups();
+
+        assertThat(tempDir, hasNChildren(1));
+
+        Path backupPath = tempDir.resolve("file_0");
+        String backupFileContent = Files.readString(backupPath);
+        assertThat(backupFileContent, is("NEW_CONTENT"));
+    }
+
+    @Test
+    void threeBackupsWithExistingFiles(@TempDir Path tempDir) throws IOException {
+        Files.writeString(baseFilePath, "A");
+
+        Path firstBackupPath = tempDir.resolve("file_0");
+        Files.writeString(firstBackupPath, "B");
+
+        Path secondBackupPath = tempDir.resolve("file_1");
+        Files.writeString(secondBackupPath, "C");
+
+        Path thirdBackupPath = tempDir.resolve("file_2");
+        Files.writeString(thirdBackupPath, "D");
+
+        assertThat(tempDir, hasNChildren(4));
+
+        RollingBackups rollingBackups = new RollingBackups(baseFilePath.toFile(), 3);
+        rollingBackups.rollBackups();
+
+        assertThat(tempDir, hasNChildren(3));
+
+        String firstBackupFileContent = Files.readString(firstBackupPath);
+        assertThat(firstBackupFileContent, is("A"));
+
+        String secondBackupFileContent = Files.readString(secondBackupPath);
+        assertThat(secondBackupFileContent, is("B"));
+
+        String thirdBackupFileContent = Files.readString(thirdBackupPath);
+        assertThat(thirdBackupFileContent, is("C"));
+    }
+
+    @Test
+    void threeBackupsFirstBackupMissing(@TempDir Path tempDir) throws IOException {
+        Files.writeString(baseFilePath, "A");
+
+        Path secondBackupPath = tempDir.resolve("file_1");
+        Files.writeString(secondBackupPath, "C");
+
+        Path thirdBackupPath = tempDir.resolve("file_2");
+        Files.writeString(thirdBackupPath, "D");
+
+        assertThat(tempDir, hasNChildren(3));
+
+        RollingBackups rollingBackups = new RollingBackups(baseFilePath.toFile(), 3);
+        rollingBackups.rollBackups();
+
+        assertThat(tempDir, hasNChildren(2));
+
+        Path firstBackupPath = tempDir.resolve("file_0");
+        String firstBackupFileContent = Files.readString(firstBackupPath);
+        assertThat(firstBackupFileContent, is("A"));
+
+        String thirdBackupFileContent = Files.readString(thirdBackupPath);
+        assertThat(thirdBackupFileContent, is("C"));
+    }
+
+    @Test
+    void threeBackupsFileMissingInMiddles(@TempDir Path tempDir) throws IOException {
+        Files.writeString(baseFilePath, "A");
+
+        Path firstBackupPath = tempDir.resolve("file_0");
+        Files.writeString(firstBackupPath, "B");
+
+        Path thirdBackupPath = tempDir.resolve("file_2");
+        Files.writeString(thirdBackupPath, "D");
+
+        assertThat(tempDir, hasNChildren(3));
+
+        RollingBackups rollingBackups = new RollingBackups(baseFilePath.toFile(), 3);
+        rollingBackups.rollBackups();
+
+        assertThat(tempDir, hasNChildren(3));
+
+        String firstBackupFileContent = Files.readString(firstBackupPath);
+        assertThat(firstBackupFileContent, is("A"));
+
+        Path secondBackupPath = tempDir.resolve("file_1");
+        String secondBackupFileContent = Files.readString(secondBackupPath);
+        assertThat(secondBackupFileContent, is("B"));
+
+        // Stays the same
+        String thirdBackupFileContent = Files.readString(thirdBackupPath);
+        assertThat(thirdBackupFileContent, is("D"));
+    }
+}