customizable db locking during migration (launchbadge#2063)

* customizable db locking during migration * Update sqlx-core/src/migrate/migrator.rs Co-authored-by: Austin Bonander <austin.bonander@gmail.com> * [migrator.rs] cargo fmt * fix Migrator 'locking' param doctest fail Co-authored-by: Austin Bonander <austin.bonander@gmail.com>

Author: fuzzbuck

sqlx-core/src/migrate/migrator.rs

@@ -9,6 +9,7 @@ use std::slice;
 pub struct Migrator {
  pub migrations: Cow<'static, [Migration]>,
  pub ignore_missing: bool,
+ pub locking: bool,
 }
 
 fn validate_applied_migrations(
@@ -56,6 +57,7 @@ impl Migrator {
  Ok(Self {
  migrations: Cow::Owned(source.resolve().await.map_err(MigrateError::Source)?),
  ignore_missing: false,
+ locking: true,
  })
  }
 
@@ -65,6 +67,19 @@ impl Migrator {
  self
  }
 
+ /// Specify whether or not to lock database during migration. Defaults to `true`.
+ ///
+ /// ### Warning
+ /// Disabling locking can lead to errors or data loss if multiple clients attempt to apply migrations simultaneously
+ /// without some sort of mutual exclusion.
+ ///
+ /// This should only be used if the database does not support locking, e.g. CockroachDB which talks the Postgres
+ /// protocol but does not support advisory locks used by SQLx's migrations support for Postgres.
+ pub fn set_locking(&mut self, locking: bool) -> &Self {
+ self.locking = locking;
+ self
+ }
+
  /// Get an iterator over all known migrations.
  pub fn iter(&self) -> slice::Iter<'_, Migration> {
  self.migrations.iter()
@@ -103,7 +118,9 @@ impl Migrator {
  C: Migrate,
  {
  // lock the database for exclusive access by the migrator
- conn.lock().await?;
+ if self.locking {
+ conn.lock().await?;
+ }
 
  // creates [_migrations] table only if needed
  // eventually this will likely migrate previous versions of the table
@@ -141,7 +158,9 @@ impl Migrator {
 
  // unlock the migrator to allow other migrators to run
  // but do nothing as we already migrated
- conn.unlock().await?;
+ if self.locking {
+ conn.unlock().await?;
+ }
 
  Ok(())
  }
@@ -170,7 +189,9 @@ impl Migrator {
  let mut conn = migrator.acquire().await?;
 
  // lock the database for exclusive access by the migrator
- conn.lock().await?;
+ if self.locking {
+ conn.lock().await?;
+ }
 
  // creates [_migrations] table only if needed
  // eventually this will likely migrate previous versions of the table
@@ -201,7 +222,9 @@ impl Migrator {
 
  // unlock the migrator to allow other migrators to run
  // but do nothing as we already migrated
- conn.unlock().await?;
+ if self.locking {
+ conn.unlock().await?;
+ }
 
  Ok(())
  }

sqlx-macros/src/migrate.rs

@@ -146,6 +146,7 @@ pub(crate) fn expand_migrator(path: &Path) -> crate::Result<TokenStream> {
  #(#migrations),*
  ]),
  ignore_missing: false,
+ locking: true,
  }
  })
 }

src/macros/test.md

@@ -132,6 +132,7 @@ use sqlx::PgPool;
 # static MIGRATOR: sqlx::migrate::Migrator = sqlx::migrate::Migrator {
 # migrations: Cow::Borrowed(&[]),
 # ignore_missing: false,
+# locking: true,
 # };
 # }