feat: get_next_job_to_run

DESCRIPTION
    Next job is the oldest job with  NULL for `scheduled_at` and
    `finished_at` and `JOB_STATE_CREATE` for state.

src/db.rs

@@ -267,6 +267,28 @@ impl Database {
 
         Ok(())
     }
+
+    pub async fn get_next_job_to_run(&self) -> ServiceResult<SchedulerJob> {
+        let res = sqlx::query_as!(
+            SchedulerJob,
+            "SELECT
+                auth, commit_hash
+            FROM
+                ftest_jobs
+            WHERE
+                job_state = (SELECT ID FROM ftest_job_states WHERE name = $1) 
+            AND
+                finished_at is NULL
+            AND
+                scheduled_at is NULL
+            ORDER BY created_at ASC;",
+            &JOB_STATE_CREATE.name
+        )
+        .fetch_one(&self.pool)
+        .await
+        .map_err(map_register_err)?;
+        Ok(res)
+    }
 }
 
 fn now_unix_time_stamp() -> OffsetDateTime {
@@ -294,7 +316,13 @@ pub fn map_row_not_found_err(e: sqlx::Error, row_not_found: ServiceError) -> Ser
     }
 }
 
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct SchedulerJob {
+    pub commit_hash: String,
+    pub auth: String,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Job {
     pub state: JobState,
     pub commit_hash: String,
@@ -374,6 +402,7 @@ mod tests {
         assert!(db.ping().await);
 
         const COMMIT_HASH: &str = "pasdfasdfasdfadf";
+        const COMMIT_HASH2: &str = "pasdfasdfasdfadf22";
 
         db.migrate().await.unwrap();
 
@@ -383,15 +412,24 @@ mod tests {
         }
 
         let _ = db.delete_job(COMMIT_HASH).await;
+        let _ = db.delete_job(COMMIT_HASH2).await;
 
         let auth = db.add_job(COMMIT_HASH).await.unwrap();
         let job = db.get_job(COMMIT_HASH).await.unwrap();
+        db.add_job(COMMIT_HASH2).await.unwrap();
+        let job2 = db.get_job(COMMIT_HASH2).await.unwrap();
+
+        assert_eq!(
+            db.get_next_job_to_run().await.unwrap().commit_hash,
+            job.commit_hash
+        );
+
         assert!(job.created_at < now_unix_time_stamp());
         assert!(job.scheduled_at.is_none());
         assert!(job.finished_at.is_none());
         assert_eq!(
             db.get_all_jobs_of_state(&*JOB_STATE_CREATE).await.unwrap(),
-            vec![job]
+            vec![job, job2.clone()]
         );
 
         db.mark_job_scheduled(&auth).await.unwrap();
@@ -409,5 +447,9 @@ mod tests {
             db.get_all_jobs_of_state(&*JOB_STATE_FINISH).await.unwrap(),
             vec![job]
         );
+        assert_eq!(
+            db.get_next_job_to_run().await.unwrap().commit_hash,
+            job2.commit_hash
+        );
     }
 }