Handle duplicate build_ref creation by upserting on conflict

Author: barthalion

src/api/build.rs

@@ -439,15 +439,23 @@ async fn create_build_ref_async(
 
     has_token_for_build(&req, &build)?;
 
-    let buildref = db
-        .new_build_ref(NewBuildRef {
-            build_id,
-            ref_name: args.ref_name.clone(),
-            commit: args.commit.clone(),
-            build_log_url: args.build_log_url.clone(),
-        })
+    let existing_ref = db
+        .lookup_build_ref_by_name(build_id, args.ref_name.clone())
         .await?;
 
+    let buildref = match existing_ref {
+        Some(existing) if existing.commit == args.commit => existing,
+        _ => {
+            db.upsert_build_ref(NewBuildRef {
+                build_id,
+                ref_name: args.ref_name.clone(),
+                commit: args.commit.clone(),
+                build_log_url: args.build_log_url.clone(),
+            })
+            .await?
+        }
+    };
+
     respond_with_url(
         &buildref,
         &req,

src/db.rs

@@ -455,16 +455,6 @@ impl Db {
 
     /* Build refs */
 
-    pub async fn new_build_ref(&self, a_build_ref: NewBuildRef) -> Result<BuildRef, ApiError> {
-        self.run(move |conn| {
-            use self::schema::build_refs::dsl::*;
-            Ok(diesel::insert_into(build_refs)
-                .values(&a_build_ref)
-                .get_result::<BuildRef>(conn)?)
-        })
-        .await
-    }
-
     pub async fn lookup_build_ref(
         &self,
         the_build_id: i32,
@@ -490,6 +480,39 @@ impl Db {
         .await
     }
 
+    pub async fn lookup_build_ref_by_name(
+        &self,
+        the_build_id: i32,
+        the_ref_name: String,
+    ) -> Result<Option<BuildRef>, ApiError> {
+        self.run(move |conn| {
+            use schema::build_refs::dsl::*;
+            Ok(build_refs
+                .filter(build_id.eq(the_build_id))
+                .filter(ref_name.eq(the_ref_name))
+                .first::<BuildRef>(conn)
+                .optional()?)
+        })
+        .await
+    }
+
+    pub async fn upsert_build_ref(&self, a_build_ref: NewBuildRef) -> Result<BuildRef, ApiError> {
+        self.run(move |conn| {
+            use self::schema::build_refs::dsl::*;
+            use diesel::pg::upsert::excluded;
+            Ok(diesel::insert_into(build_refs)
+                .values(&a_build_ref)
+                .on_conflict((build_id, ref_name))
+                .do_update()
+                .set((
+                    commit.eq(excluded(commit)),
+                    build_log_url.eq(excluded(build_log_url)),
+                ))
+                .get_result::<BuildRef>(conn)?)
+        })
+        .await
+    }
+
     /// Checks whether the given token has been revoked. If it hasn't, update its last used time.
     pub async fn check_token(&self, jti: String, expires_at: i64) -> Result<(), ApiError> {
         self.run_in_transaction(move |conn| {