BackupService backwards compatibility

atlasdb-backup/src/main/java/com/palantir/atlasdb/backup/ExternalBackupPersister.java

@@ -17,6 +17,9 @@
 package com.palantir.atlasdb.backup;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.PropertyNamingStrategies;
+import com.fasterxml.jackson.databind.exc.MismatchedInputException;
+import com.google.common.annotations.VisibleForTesting;
 import com.palantir.atlasdb.backup.api.AtlasService;
 import com.palantir.atlasdb.backup.api.CompletedBackup;
 import com.palantir.atlasdb.backup.api.InProgressBackupToken;
@@ -37,6 +40,9 @@ public class ExternalBackupPersister implements BackupPersister {
     private static final SafeLogger log = SafeLoggerFactory.get(ExternalBackupPersister.class);
 
     private static final ObjectMapper OBJECT_MAPPER = ObjectMappers.newClientObjectMapper();
+    private static final ObjectMapper LEGACY_OBJECT_MAPPER =
+            OBJECT_MAPPER.copy().setPropertyNamingStrategy(PropertyNamingStrategies.KEBAB_CASE);
+
     private static final String SCHEMA_METADATA_FILE_NAME = "internal_schema_metadata_state";
     private static final String BACKUP_TIMESTAMP_FILE_NAME = "backup.timestamp";
     private static final String IMMUTABLE_TIMESTAMP_FILE_NAME = "immutable.timestamp";
@@ -138,21 +144,22 @@ private void writeToFile(AtlasService atlasService, File file, Object data) {
         }
     }
 
-    private <T> Optional<T> loadFromFile(AtlasService atlasService, File file, Class<T> clazz) {
+    @VisibleForTesting
+    <T> Optional<T> loadFromFile(AtlasService atlasService, File file, Class<T> clazz) {
         if (!file.exists()) {
             log.info(
                     "Tried to load file, but it did not exist",
                     SafeArg.of("fileName", file.getName()),
-                    SafeArg.of("atlasService", atlasService));
+                    SafeArg.of("namespace", atlasService.getNamespace()));
             return Optional.empty();
         }
 
         try {
-            T state = OBJECT_MAPPER.readValue(file, clazz);
+            T state = tryLoadFromFile(file, clazz);
             log.info(
                     "Successfully loaded file",
                     SafeArg.of("fileName", file.getName()),
-                    SafeArg.of("atlasService", atlasService));
+                    SafeArg.of("namespace", atlasService.getNamespace()));
             return Optional.of(state);
         } catch (IOException e) {
             log.warn(
@@ -163,4 +170,13 @@ private <T> Optional<T> loadFromFile(AtlasService atlasService, File file, Class
             return Optional.empty();
         }
     }
+
+    private <T> T tryLoadFromFile(File file, Class<T> clazz) throws IOException {
+        try {
+            return OBJECT_MAPPER.readValue(file, clazz);
+        } catch (MismatchedInputException e) {
+            log.debug("Using old mapper format", e);
+            return LEGACY_OBJECT_MAPPER.readValue(file, clazz);
+        }
+    }
 }

atlasdb-backup/src/test/java/com/palantir/atlasdb/backup/ExternalBackupPersisterTest.java

@@ -27,9 +27,13 @@
 import com.palantir.atlasdb.internalschema.InternalSchemaMetadataState;
 import com.palantir.atlasdb.timelock.api.Namespace;
 import com.palantir.lock.v2.LockToken;
+import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 import java.util.UUID;
 import org.junit.Before;
 import org.junit.Rule;
@@ -101,6 +105,22 @@ public void putAndGetCompletedBackup() {
         assertThat(externalBackupPersister.getCompletedBackup(ATLAS_SERVICE)).contains(completedBackup);
     }
 
+    @Test
+    public void testLegacyCasing() throws IOException {
+        String legacyState = "{\"value\":{\"value\":{\"timestampToTransactionsTableSchemaVersion\":{\"timestampMappings"
+            + "\":[{\"longRange\":{\"lower-endpoint\":1316020054,\"lower-bound-type\":\"CLOSED\"},\"value\":3},{\"longRange\":{\"lower-endpoint\":1,\"lower-bound-type\":\"CLOSED\",\"upper-endpoint\":1316020054,\"upper-bound-type\":\"OPEN\"},\"value\":1}]}},\"bound\":1318613869}}";
+        File tempFile = tempFolder.newFile();
+        Files.copy(
+                new ByteArrayInputStream(legacyState.getBytes(StandardCharsets.UTF_8)),
+                tempFile.toPath(),
+                StandardCopyOption.REPLACE_EXISTING);
+
+        InternalSchemaMetadataState parsed = externalBackupPersister
+                .loadFromFile(ATLAS_SERVICE, tempFile, InternalSchemaMetadataState.class)
+                .get();
+        assertThat(parsed).isNotNull();
+    }
+
     private Path getPath(AtlasService atlasService) {
         try {
             return getOrCreateFolder(atlasService).toPath();

changelog/0.610.0-rc1/pr-6040.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Backup Service can now deserialise metadata persisted from older formats.
+  links:
+  - https://github.com/palantir/atlasdb/pull/6040

changelog/@unreleased/pr-6040.v2.yml

@@ -0,0 +1,5 @@
+type: improvement
+improvement:
+  description: Backup Service can now deserialise metadata persisted from older formats.
+  links:
+  - https://github.com/palantir/atlasdb/pull/6040