Revert "Revert "diff_checker (partial)""

This reverts commit d4bdda5d11.

Cargo.lock

@@ -2833,6 +2833,7 @@ dependencies = [
  "serde_json",
  "serde_with",
  "serial_test",
+ "string-interner",
  "strum",
  "strum_macros",
  "tokio",
@@ -5228,6 +5229,17 @@ dependencies = [
  "pin-project-lite",
 ]
 
+[[package]]
+name = "string-interner"
+version = "0.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c6a0d765f5807e98a091107bae0a56ea3799f66a5de47b2c84c94a39c09974e"
+dependencies = [
+ "cfg-if",
+ "hashbrown 0.14.3",
+ "serde",
+]
+
 [[package]]
 name = "string_cache"
 version = "0.8.7"

crates/db_schema/Cargo.toml

@@ -85,6 +85,7 @@ moka.workspace = true
 [dev-dependencies]
 serial_test = { workspace = true }
 pretty_assertions = { workspace = true }
+string-interner = { version = "0.17.0", features = ["inline-more", "backends"] }
 
 [package.metadata.cargo-machete]
 ignored = ["strum"]

crates/db_schema/src/schema_setup.rs

@@ -1,3 +1,6 @@
+#[cfg(test)]
+mod diff_checker;
+
 use crate::schema::previously_run_sql;
 use anyhow::{anyhow, Context};
 use diesel::{
@@ -17,6 +20,8 @@ use diesel_migrations::MigrationHarness;
 use lemmy_utils::error::{LemmyError, LemmyResult};
 use std::time::Instant;
 use tracing::info;
+use lemmy_utils::settings::SETTINGS;
+use std::collections::BTreeMap;
 
 // In production, include migrations in the binary
 #[cfg(not(debug_assertions))]
@@ -96,20 +101,40 @@ impl<'a, T: MigrationSource<Pg>> MigrationSource<Pg> for MigrationSourceRef<&'a
 }
 
 #[derive(Default)]
-pub struct Options {
+struct DiffChecker {
+  /// Maps a migration name to the schema that exists before the migration is applied
+  schema_before: BTreeMap<String, Schema>,
+  /// Stores strings 
+}
+
+#[derive(Default)]
+struct Schema {
+  indexes: BTreeMap<String, >
+}
+
+#[derive(Default)]
+pub struct Options<'a> {
   enable_forbid_diesel_cli_trigger: bool,
   revert: bool,
   revert_amount: Option<u64>,
   redo_after_revert: bool,
+  #[cfg(test)]
+  diff_checker: Option<&'a mut diff_checker::DiffChecker>,
 }
 
-impl Options {
+impl<'a> Options<'a> {
   #[cfg(test)]
   fn enable_forbid_diesel_cli_trigger(mut self) -> Self {
     self.enable_forbid_diesel_cli_trigger = true;
     self
   }
 
+  #[cfg(test)]
+  fn diff_checker(mut self, diff_checker: &'a mut diff_checker::DiffChecker) -> Self {
+    self.diff_checker = Some(diff_checker);
+    self
+  }
+
   pub fn revert(mut self, amount: Option<u64>) -> Self {
     self.revert = true;
     self.revert_amount = amount;
@@ -122,14 +147,15 @@ impl Options {
   }
 }
 
-pub fn run(db_url: &str, options: Options) -> LemmyResult<()> {
+pub fn run(options: Options) -> LemmyResult<()> {
+  let db_url = SETTINGS.get_database_url();
+
   // Migrations don't support async connection, and this function doesn't need to be async
   let mut conn = PgConnection::establish(db_url).with_context(|| "Error connecting to database")?;
 
   let new_sql = REPLACEABLE_SCHEMA.join("\n");
 
   let migration_source = get_migration_source();
-
   let migration_source_ref = MigrationSourceRef(&migration_source);
 
   // If possible, skip locking the migrations table and recreating the "r" schema, so
@@ -228,24 +254,26 @@ mod tests {
   #[test]
   #[serial]
   fn test_schema_setup() -> LemmyResult<()> {
-    let url = SETTINGS.get_database_url();
+    let db_url = SETTINGS.get_database_url();
-    let mut conn = PgConnection::establish(&url)?;
+    let mut conn = PgConnection::establish(&db_url)?;
+    let diff_checker = DiffChecker::default();
+    let options = || Options::default().diff_checker(&mut diff_checker);
 
     // Start with consistent state by dropping everything
     conn.batch_execute("DROP OWNED BY CURRENT_USER;")?;
 
     // Run and revert all migrations, ensuring there's no mistakes in any down.sql file
-    run(&url, Options::default())?;
+    run(options())?;
-    run(&url, Options::default().revert(None))?;
+    run(options().revert(None))?;
 
     // TODO also don't drop r, and maybe just directly call the migrationharness method here
     assert!(matches!(
-      run(&url, Options::default().enable_forbid_diesel_cli_trigger()),
+      run(options().enable_forbid_diesel_cli_trigger()),
       Err(e) if e.to_string().contains("lemmy_server")
     ));
 
     // Previous run shouldn't stop this one from working
-    run(&url, Options::default())?;
+    run(options())?;
 
     Ok(())
   }

crates/db_schema/src/utils.rs

@@ -427,7 +427,7 @@ pub async fn build_db_pool() -> LemmyResult<ActualDbPool> {
     }))
     .build()?;
 
-  crate::schema_setup::run(&db_url, Default::default())?;
+  crate::schema_setup::run(Default::default())?;
 
   Ok(pool)
 }

src/lib.rs

@@ -133,7 +133,7 @@ pub async fn start_lemmy_server(args: CmdArgs) -> LemmyResult<()> {
       MigrationSubcommand::Run => schema_setup::Options::default(),
     };
 
-    schema_setup::run(&SETTINGS.get_database_url(), options)?;
+    schema_setup::run(options)?;
 
     return Ok(());
   }