Enable evaluation cache in the readonly evaluation API. (#42)

* Cleanup unnecessary casts.

* Enable evaluation cache in the readonly evaluation API.

Author: badmonster0

src/execution/indexer.rs

@@ -413,14 +413,41 @@ async fn commit_source_tracking_info(
     Ok(WithApplyStatus::Normal(()))
 }
 
+/// Built an evaluation cache on the existing data.
+pub async fn evaluation_cache_on_existing_data(
+    plan: &ExecutionPlan,
+    source_op_idx: usize,
+    key: &value::KeyValue,
+    pool: &PgPool,
+) -> Result<EvaluationCache> {
+    let source_id = plan.source_ops[source_op_idx].source_id;
+    let source_key_json = serde_json::to_value(key)?;
+    let existing_tracking_info = read_source_tracking_info(
+        source_id,
+        &source_key_json,
+        &plan.tracking_table_setup,
+        pool,
+    )
+    .await?;
+    let process_timestamp = chrono::Utc::now();
+    let memoization_info = existing_tracking_info
+        .map(|info| info.memoization_info.map(|info| info.0))
+        .flatten()
+        .flatten();
+    Ok(EvaluationCache::new(
+        process_timestamp,
+        memoization_info.map(|info| info.cache),
+    ))
+}
+
 pub async fn update_source_entry<'a>(
     plan: &ExecutionPlan,
     source_op_idx: usize,
     schema: &schema::DataSchema,
     key: &value::KeyValue,
     pool: &PgPool,
 ) -> Result<()> {
-    let source_id = plan.source_ops[source_op_idx as usize].source_id;
+    let source_id = plan.source_ops[source_op_idx].source_id;
     let source_key_json = serde_json::to_value(key)?;
     let process_timestamp = chrono::Utc::now();
 
@@ -532,7 +559,7 @@ async fn update_source(
     schema: &schema::DataSchema,
     pool: &PgPool,
 ) -> Result<SourceUpdateInfo> {
-    let source_op = &plan.source_ops[source_op_idx as usize];
+    let source_op = &plan.source_ops[source_op_idx];
     let (keys, existing_keys_json) = try_join(
         source_op.executor.list_keys(),
         db_tracking::list_source_tracking_keys(

src/service/flows.rs

@@ -145,12 +145,22 @@ pub async fn evaluate_data(
         .ok_or_else(|| api_error!("field {} does not have a key", query.field))?;
     let key = value::KeyValue::from_strs(query.key, &key_field.value_type.typ)?;
 
-    let data_builder =
-        evaluator::evaluate_source_entry(&execution_plan, source_op_idx, &schema, &key, None)
-            .await?
-            .ok_or_else(|| {
-                api_error!("value not found for source at the specified key: {key:?}")
-            })?;
+    let evaluation_cache = indexer::evaluation_cache_on_existing_data(
+        &execution_plan,
+        source_op_idx,
+        &key,
+        &lib_context.pool,
+    )
+    .await?;
+    let data_builder = evaluator::evaluate_source_entry(
+        &execution_plan,
+        source_op_idx,
+        &schema,
+        &key,
+        Some(&evaluation_cache),
+    )
+    .await?
+    .ok_or_else(|| api_error!("value not found for source at the specified key: {key:?}"))?;
 
     Ok(Json(EvaluateDataResponse {
         schema: schema.clone(),