Fix exception on RocksDB.getColumnFamilyMetaData() (#12474)

Summary:
facebook/rocksdb#12466 reported a bug when `RocksDB.getColumnFamilyMetaData()` is called on an existing database(With files stored on disk). As neilramaswamy mentioned, this was caused by facebook/rocksdb#11770 where the signature of `SstFileMetaData` constructor was changed, but JNI code wasn't updated.

This PR fix JNI code, and also properly populate `fileChecksum` on `SstFileMetaData`.

Pull Request resolved: facebook/rocksdb#12474

Reviewed By: jowlyzhang

Differential Revision: D55811808

Pulled By: ajkr

fbshipit-source-id: 2ab156f41eaf4a4f30c49e6df421b61e8451230e
(cherry picked from commit a8035ebc0b22f079a447bdc6b0aeeb2f1cf09d47)

Author: rhubner

java/rocksjni/portal.h

@@ -7569,7 +7569,8 @@ class SstFileMetaDataJni : public JavaClass {
     }
 
     jmethodID mid = env->GetMethodID(
-        jclazz, "<init>", "(Ljava/lang/String;Ljava/lang/String;JJJ[B[BJZJJ)V");
+        jclazz, "<init>",
+        "(Ljava/lang/String;Ljava/lang/String;JJJ[B[BJZJJ[B)V");
     if (mid == nullptr) {
       // exception thrown: NoSuchMethodException or OutOfMemoryError
       return nullptr;
@@ -7609,6 +7610,17 @@ class SstFileMetaDataJni : public JavaClass {
       return nullptr;
     }
 
+    jbyteArray jfile_checksum = ROCKSDB_NAMESPACE::JniUtil::copyBytes(
+        env, sst_file_meta_data->file_checksum);
+    if (env->ExceptionCheck()) {
+      // exception occurred creating java string
+      env->DeleteLocalRef(jfile_name);
+      env->DeleteLocalRef(jpath);
+      env->DeleteLocalRef(jsmallest_key);
+      env->DeleteLocalRef(jlargest_key);
+      return nullptr;
+    }
+
     jobject jsst_file_meta_data = env->NewObject(
         jclazz, mid, jfile_name, jpath,
         static_cast<jlong>(sst_file_meta_data->size),
@@ -7617,13 +7629,14 @@ class SstFileMetaDataJni : public JavaClass {
         jlargest_key, static_cast<jlong>(sst_file_meta_data->num_reads_sampled),
         static_cast<jboolean>(sst_file_meta_data->being_compacted),
         static_cast<jlong>(sst_file_meta_data->num_entries),
-        static_cast<jlong>(sst_file_meta_data->num_deletions));
+        static_cast<jlong>(sst_file_meta_data->num_deletions), jfile_checksum);
 
     if (env->ExceptionCheck()) {
       env->DeleteLocalRef(jfile_name);
       env->DeleteLocalRef(jpath);
       env->DeleteLocalRef(jsmallest_key);
       env->DeleteLocalRef(jlargest_key);
+      env->DeleteLocalRef(jfile_checksum);
       return nullptr;
     }
 
@@ -7632,6 +7645,7 @@ class SstFileMetaDataJni : public JavaClass {
     env->DeleteLocalRef(jpath);
     env->DeleteLocalRef(jsmallest_key);
     env->DeleteLocalRef(jlargest_key);
+    env->DeleteLocalRef(jfile_checksum);
 
     return jsst_file_meta_data;
   }

java/src/test/java/org/rocksdb/RocksDBTest.java

@@ -1409,6 +1409,33 @@ public void getLiveFilesMetadataWithChecksum() throws RocksDBException {
     }
   }
 
+  @Test
+  public void getColumnFamilyMetadataWithChecksum() throws RocksDBException {
+    final Properties props = new Properties();
+    props.put("file_checksum_gen_factory", "FileChecksumGenCrc32cFactory");
+    final String dbPath = dbFolder.getRoot().getAbsolutePath();
+
+    try (final DBOptions dbOptions = DBOptions.getDBOptionsFromProps(props);
+         final ColumnFamilyOptions cfOptions = new ColumnFamilyOptions();
+         final Options options = new Options(dbOptions, cfOptions).setCreateIfMissing(true)) {
+      try (final RocksDB db = RocksDB.open(options, dbPath);
+           final WriteOptions writeOptions = new WriteOptions().setDisableWAL(true)) {
+        db.put("key".getBytes(UTF_8), "value".getBytes(UTF_8));
+      }
+
+      try (final RocksDB db = RocksDB.open(options, dbFolder.getRoot().getAbsolutePath())) {
+        ColumnFamilyMetaData metadata = db.getColumnFamilyMetaData(); // Exception here
+        List<LevelMetaData> levels = metadata.levels();
+        assertThat(levels).isNotEmpty();
+        List<SstFileMetaData> filesMetadata = levels.get(0).files();
+        assertThat(filesMetadata).isNotEmpty();
+        assertThat(filesMetadata.get(0).fileChecksum()).isNotNull();
+        assertThat(filesMetadata.get(0).fileChecksum()).hasSize(4);
+        assertThat(filesMetadata.get(0).fileChecksum()).isNotEqualTo(new byte[] {0, 0, 0, 0});
+      }
+    }
+  }
+
   @Ignore("TODO(AR) re-enable when ready!")
   @Test
   public void compactFiles() throws RocksDBException {