Enforce max batch size in CustomPredicateBatchBuilder

Author: robknight

src/frontend/custom.rs

@@ -184,6 +184,14 @@ impl CustomPredicateBatchBuilder {
         priv_args: &[&str],
         sts: &[StatementTmplBuilder],
     ) -> Result<Predicate> {
+        if self.predicates.len() >= self.params.max_custom_batch_size {
+            return Err(Error::max_length(
+                "self.predicates.len".to_string(),
+                self.predicates.len(),
+                self.params.max_custom_batch_size,
+            ));
+        }
+
         if args.len() > self.params.max_statement_args {
             return Err(Error::max_length(
                 "args.len".to_string(),

src/lang/processor.rs

@@ -208,14 +208,6 @@ fn second_pass(ctx: &mut ProcessingContext) -> Result<ProcessedOutput, Processor
 
     let custom_batch = cpb_builder.finish();
 
-    if custom_batch.predicates.len() > ctx.params.max_custom_batch_size {
-        return Err(ProcessorError::Middleware(middleware::Error::max_length(
-            "custom predicates".to_string(),
-            custom_batch.predicates.len(),
-            ctx.params.max_custom_batch_size,
-        )));
-    }
-
     let request_templates = if let Some(req_pair) = &ctx.request_pair {
         process_request_def(req_pair, ctx, &custom_batch)?
     } else {

src/middleware/custom.rs

@@ -379,14 +379,6 @@ pub struct CustomPredicateBatch {
 impl ToFields for CustomPredicateBatch {
     fn to_fields(&self, params: &Params) -> Vec<F> {
         // all the custom predicates in order
-
-        // TODO think if this check should go into the StatementTmpl creation,
-        // instead of at the `to_fields` method, where we should assume that the
-        // values are already valid
-        if self.predicates.len() > params.max_custom_batch_size {
-            panic!("Predicate batch exceeds maximum size");
-        }
-
         let pad_pred = CustomPredicate::empty();
         let fields: Vec<F> = self
             .predicates