Merge pull request #2334 from ethcore/fix-migrations

fix migration system for post-consolidation migrations, better errors

parity/migration.rs

@@ -43,13 +43,15 @@ pub enum Error {
 	/// Returned when current version cannot be read or guessed.
 	UnknownDatabaseVersion,
 	/// Migration does not support existing pruning algorithm.
-	UnsuportedPruningMethod,
+	UnsupportedPruningMethod,
 	/// Existing DB is newer than the known one.
 	FutureDBVersion,
 	/// Migration is not possible.
 	MigrationImpossible,
 	/// Migration unexpectadly failed.
 	MigrationFailed,
+	/// Internal migration error.
+	Internal(MigrationError),
 	/// Migration was completed succesfully,
 	/// but there was a problem with io.
 	Io(IoError),
@@ -59,10 +61,11 @@ impl Display for Error {
 	fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
 		let out = match *self {
 			Error::UnknownDatabaseVersion => "Current database version cannot be read".into(),
-			Error::UnsuportedPruningMethod => "Unsupported pruning method for database migration. Delete DB and resync.".into(),
+			Error::UnsupportedPruningMethod => "Unsupported pruning method for database migration. Delete DB and resync.".into(),
 			Error::FutureDBVersion => "Database was created with newer client version. Upgrade your client or delete DB and resync.".into(),
 			Error::MigrationImpossible => format!("Database migration to version {} is not possible.", CURRENT_VERSION),
 			Error::MigrationFailed => "Database migration unexpectedly failed".into(),
+			Error::Internal(ref err) => format!("{}", err),
 			Error::Io(ref err) => format!("Unexpected io error on DB migration: {}.", err),
 		};
 
@@ -80,7 +83,7 @@ impl From<MigrationError> for Error {
 	fn from(err: MigrationError) -> Self {
 		match err {
 			MigrationError::Io(e) => Error::Io(e),
-			_ => Error::MigrationFailed,
+			_ => Error::Internal(err),
 		}
 	}
 }
@@ -320,7 +323,7 @@ mod legacy {
 		let res = match pruning {
 			Algorithm::Archive => manager.add_migration(migrations::state::ArchiveV7::default()),
 			Algorithm::OverlayRecent => manager.add_migration(migrations::state::OverlayRecentV7::default()),
-			_ => return Err(Error::UnsuportedPruningMethod),
+			_ => return Err(Error::UnsupportedPruningMethod),
 		};
 
 		try!(res.map_err(|_| Error::MigrationImpossible));