From 3b2583c540c67ebf8276a550df8dd17ff574ba57 Mon Sep 17 00:00:00 2001
From: pedrocarlo <pedro.muniz.carlo@gmail.com>
Date: Tue, 7 Oct 2025 13:31:27 -0300
Subject: [PATCH] adjust Interaction generation to take into account possibilty
 of `PropertyDistribution` to have 0 Weights

---
 simulator/generation/plan.rs     | 79 ++++++++++++++++----------------
 simulator/generation/property.rs | 14 +++---
 simulator/generation/query.rs    |  5 +-
 3 files changed, 51 insertions(+), 47 deletions(-)

diff --git a/simulator/generation/plan.rs b/simulator/generation/plan.rs
index 836c24780..a468e87ec 100644
--- a/simulator/generation/plan.rs
+++ b/simulator/generation/plan.rs
@@ -1242,46 +1242,45 @@ impl ArbitraryFrom<(&SimulatorEnv, InteractionStats, usize)> for Interactions {
         let queries = possible_queries(conn_ctx.tables());
         let query_distr = QueryDistribution::new(queries, &remaining_);
 
-        let property_distr = PropertyDistribution::new(env, &remaining_, &query_distr, conn_ctx);
+        #[allow(clippy::type_complexity)]
+        let mut choices: Vec<(u32, Box<dyn Fn(&mut R) -> Interactions>)> = vec![
+            (
+                query_distr.weights().total_weight(),
+                Box::new(|rng: &mut R| {
+                    Interactions::new(
+                        conn_index,
+                        InteractionsType::Query(Query::arbitrary_from(rng, conn_ctx, &query_distr)),
+                    )
+                }),
+            ),
+            (
+                remaining_
+                    .select
+                    .min(remaining_.insert)
+                    .min(remaining_.create)
+                    .max(1),
+                Box::new(|rng: &mut R| random_fault(rng, env, conn_index)),
+            ),
+        ];
 
-        frequency(
-            vec![
-                (
-                    property_distr.weights().total_weight(),
-                    Box::new(|rng: &mut R| {
-                        Interactions::new(
-                            conn_index,
-                            InteractionsType::Property(Property::arbitrary_from(
-                                rng,
-                                conn_ctx,
-                                &property_distr,
-                            )),
-                        )
-                    }),
-                ),
-                (
-                    query_distr.weights().total_weight(),
-                    Box::new(|rng: &mut R| {
-                        Interactions::new(
-                            conn_index,
-                            InteractionsType::Query(Query::arbitrary_from(
-                                rng,
-                                conn_ctx,
-                                &query_distr,
-                            )),
-                        )
-                    }),
-                ),
-                (
-                    remaining_
-                        .select
-                        .min(remaining_.insert)
-                        .min(remaining_.create)
-                        .max(1),
-                    Box::new(|rng: &mut R| random_fault(rng, env, conn_index)),
-                ),
-            ],
-            rng,
-        )
+        if let Ok(property_distr) =
+            PropertyDistribution::new(env, &remaining_, &query_distr, conn_ctx)
+        {
+            choices.push((
+                property_distr.weights().total_weight(),
+                Box::new(move |rng: &mut R| {
+                    Interactions::new(
+                        conn_index,
+                        InteractionsType::Property(Property::arbitrary_from(
+                            rng,
+                            conn_ctx,
+                            &property_distr,
+                        )),
+                    )
+                }),
+            ));
+        };
+
+        frequency(choices, rng)
     }
 }
diff --git a/simulator/generation/property.rs b/simulator/generation/property.rs
index 8d6b4cb79..9df45db2e 100644
--- a/simulator/generation/property.rs
+++ b/simulator/generation/property.rs
@@ -274,7 +274,10 @@ impl Property {
 
     /// Property Does some sort of fault injection
     pub fn check_tables(&self) -> bool {
-        matches!(self, Property::FsyncNoWait { .. } | Property::FaultyQuery { .. })
+        matches!(
+            self,
+            Property::FsyncNoWait { .. } | Property::FaultyQuery { .. }
+        )
     }
 
     pub fn get_extensional_queries(&mut self) -> Option<&mut Vec<Query>> {
@@ -1940,21 +1943,20 @@ impl<'a> PropertyDistribution<'a> {
         remaining: &Remaining,
         query_distr: &'a QueryDistribution,
         ctx: &impl GenerationContext,
-    ) -> Self {
+    ) -> Result<Self, rand::distr::weighted::Error> {
         let properties = PropertyDiscriminants::can_generate(query_distr.items());
         let weights = WeightedIndex::new(
             properties
                 .iter()
                 .map(|property| property.weight(env, remaining, ctx)),
-        )
-        .unwrap();
+        )?;
 
-        Self {
+        Ok(Self {
             properties,
             weights,
             query_distr,
             mvcc: env.profile.experimental_mvcc,
-        }
+        })
     }
 }
 
diff --git a/simulator/generation/query.rs b/simulator/generation/query.rs
index 3408dca3b..914b44b35 100644
--- a/simulator/generation/query.rs
+++ b/simulator/generation/query.rs
@@ -120,7 +120,9 @@ impl QueryDiscriminants {
     pub fn weight(&self, remaining: &Remaining) -> u32 {
         match self {
             QueryDiscriminants::Create => remaining.create,
-            QueryDiscriminants::Select => remaining.select + remaining.select / 3, // remaining.select / 3 is for the random_expr generation
+            // remaining.select / 3 is for the random_expr generation
+            // have a max of 1 so that we always generate at least a non zero weight for `QueryDistribution`
+            QueryDiscriminants::Select => (remaining.select + remaining.select / 3).max(1),
             QueryDiscriminants::Insert => remaining.insert,
             QueryDiscriminants::Delete => remaining.delete,
             QueryDiscriminants::Update => remaining.update,
@@ -138,6 +140,7 @@ impl QueryDiscriminants {
     }
 }
 
+#[derive(Debug)]
 pub(super) struct QueryDistribution {
     queries: &'static [QueryDiscriminants],
     weights: WeightedIndex<u32>,