Merge #713: Add datatype for is_spent sqlite column

54d7684 Sqlite migrations should either succeed or fail (Vladimir Fomene)
369e17b Add datatype for is_spent sqlite column (Vladimir Fomene)

Pull request description:

  ### Description

  During table creation, Sqlite does not throw an error when a column datatype is not defined. In addition, the datatype provided during table creation does not put a constraint on the type of data that can be put in that column. So you can easily put a string value in an integer column. Despite this, I think it is important for us to add the datatype for clarity.

  ### Notes to the reviewers

  You can read more about how Sqlite dynamic typing [here](https://www.sqlite.org/faq.html). I have amended our `migrate` code with a new commit. The idea is to run migrations in a transaction so that they either succeed or fail. This prevents us from having the database in an inconsistent state at any point in time.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

  #### Bugfixes:

  * [ ] This pull request breaks the existing API
  * [ ] I've added tests to reproduce the issue which are now passing
  * [ ] I'm linking the issue being fixed by this PR

ACKs for top commit:
  rajarshimaitra:
    tACK 54d7684
  afilini:
    ACK 54d7684

Tree-SHA512: bb6c0467f799ca917f8d45c6495b766352b3177fc81952fcdd678208abf092fdeae966686528a5dcb3f342d7171783274df6312a08cbef3580063e059f5f7254

src/database/sqlite.rs

@@ -52,6 +52,11 @@ static MIGRATIONS: &[&str] = &[
     "DELETE FROM transactions;",
     "DELETE FROM utxos;",
     "DROP INDEX idx_txid_vout;",
+    "CREATE UNIQUE INDEX idx_utxos_txid_vout ON utxos(txid, vout);",
+    "ALTER TABLE utxos RENAME TO utxos_old;",
+    "CREATE TABLE utxos (value INTEGER, keychain TEXT, vout INTEGER, txid BLOB, script BLOB, is_spent BOOLEAN DEFAULT 0);",
+    "INSERT INTO utxos SELECT value, keychain, vout, txid, script, is_spent FROM utxos_old;",
+    "DROP TABLE utxos_old;",
     "CREATE UNIQUE INDEX idx_utxos_txid_vout ON utxos(txid, vout);"
 ];
 
@@ -916,8 +921,8 @@ impl BatchDatabase for SqliteDatabase {
 }
 
 pub fn get_connection<T: AsRef<Path>>(path: &T) -> Result<Connection, Error> {
-    let connection = Connection::open(path)?;
-    migrate(&connection)?;
+    let mut connection = Connection::open(path)?;
+    migrate(&mut connection)?;
     Ok(connection)
 }
 
@@ -952,28 +957,41 @@ pub fn set_schema_version(conn: &Connection, version: i32) -> rusqlite::Result<u
     )
 }
 
-pub fn migrate(conn: &Connection) -> rusqlite::Result<()> {
+pub fn migrate(conn: &mut Connection) -> Result<(), Error> {
     let version = get_schema_version(conn)?;
     let stmts = &MIGRATIONS[(version as usize)..];
-    let mut i: i32 = version;
 
-    if version == MIGRATIONS.len() as i32 {
+    // begin transaction, all migration statements and new schema version commit or rollback
+    let tx = conn.transaction()?;
+
+    // execute every statement and return `Some` new schema version
+    // if execution fails, return `Error::Rusqlite`
+    // if no statements executed returns `None`
+    let new_version = stmts
+        .iter()
+        .enumerate()
+        .map(|version_stmt| {
+            log::info!(
+                "executing db migration {}: `{}`",
+                version + version_stmt.0 as i32 + 1,
+                version_stmt.1
+            );
+            tx.execute(version_stmt.1, [])
+                // map result value to next migration version
+                .map(|_| version_stmt.0 as i32 + version + 1)
+        })
+        .last()
+        .transpose()?;
+
+    // if `Some` new statement version, set new schema version
+    if let Some(version) = new_version {
+        set_schema_version(&tx, version)?;
+    } else {
         log::info!("db up to date, no migration needed");
-        return Ok(());
     }
 
-    for stmt in stmts {
-        let res = conn.execute(stmt, []);
-        if res.is_err() {
-            println!("migration failed on:\n{}\n{:?}", stmt, res);
-            break;
-        }
-
-        i += 1;
-    }
-
-    set_schema_version(conn, i)?;
-
+    // commit transaction
+    tx.commit()?;
     Ok(())
 }