issue#135 Expose API to restore database from backups

src/backup.rs

@@ -78,6 +78,60 @@ impl BackupEngine {
             Ok(())
         }
     }
+    /// Restore from the latest backup
+    /// db_dir:  input db directory
+    /// wal_dir:  input wal directory
+    /// opts: restore options
+    /// example:
+    /// use rocksdb::backup::{BackupEngine, BackupEngineOptions};
+    /// let backup_opts = BackupEngineOptions::default();
+    /// let backup_engine = BackupEngine::open(&backup_opts, &backup_path).unwrap();
+    /// let mut restore_option = rocksdb::backup::RestoreOptions::default();
+    /// restore_option.set_keep_log_files(true); /// true to keep log files
+    /// if let Err(e) = backup_engine.restore_from_latest_backup(&db_path, &wal_dir, &restore_option) {
+    ///     error!("Failed to restore from the backup. Error:{:?}", e);
+    ///     return Err(e.to_string());
+    ///  }
+    pub fn restore_from_latest_backup<P: AsRef<Path>>(
+        &mut self,
+        db_dir: P,
+        wal_dir: P,
+        opts: &RestoreOptions,
+    ) -> Result<(), Error> {
+        let db_dir = db_dir.as_ref();
+        let c_db_dir = match CString::new(db_dir.to_string_lossy().as_bytes()) {
+            Ok(c) => c,
+            Err(_) => {
+                return Err(Error::new(
+                    "Failed to convert db_dir to CString \
+                     when restoring from latest backup"
+                        .to_owned(),
+                ));
+            }
+        };
+
+        let wal_dir = wal_dir.as_ref();
+        let c_wal_dir = match CString::new(wal_dir.to_string_lossy().as_bytes()) {
+            Ok(c) => c,
+            Err(_) => {
+                return Err(Error::new(
+                    "Failed to convert wal_dir to CString \
+                     when restoring from latest backup"
+                        .to_owned(),
+                ));
+            }
+        };
+
+        unsafe {
+            ffi_try!(ffi::rocksdb_backup_engine_restore_db_from_latest_backup(
+                self.inner,
+                c_db_dir.as_ptr(),
+                c_wal_dir.as_ptr(),
+                opts.inner,
+            ));
+        }
+        Ok(())
+    }
 }
 
 impl BackupEngineOptions {