From 9c6e7e0435fced43f5b1a864e08ea32ce5cb1c24 Mon Sep 17 00:00:00 2001
From: Pankaj Garg <pankaj@solana.com>
Date: Fri, 5 May 2023 06:08:57 -0700
Subject: [PATCH] Return implicit delay visibility tombstone (#31493)

---
 program-runtime/src/loaded_programs.rs | 59 +++++++++++++++++++++-----
 1 file changed, 49 insertions(+), 10 deletions(-)

diff --git a/program-runtime/src/loaded_programs.rs b/program-runtime/src/loaded_programs.rs
index 1b32d6dbce..001276db0c 100644
--- a/program-runtime/src/loaded_programs.rs
+++ b/program-runtime/src/loaded_programs.rs
@@ -25,6 +25,7 @@ use {
 };
 
 const MAX_LOADED_ENTRY_COUNT: usize = 256;
+const DELAY_VISIBILITY_SLOT_OFFSET: Slot = 1;
 
 /// Relationship between two fork IDs
 #[derive(Copy, Clone, PartialEq)]
@@ -231,8 +232,8 @@ impl LoadedProgram {
     }
 
     pub fn new_tombstone(slot: Slot, reason: LoadedProgramType) -> Self {
-        let maybe_expiration_slot =
-            matches!(reason, LoadedProgramType::DelayVisibility).then_some(slot.saturating_add(1));
+        let maybe_expiration_slot = matches!(reason, LoadedProgramType::DelayVisibility)
+            .then_some(slot.saturating_add(DELAY_VISIBILITY_SLOT_OFFSET));
         let tombstone = Self {
             program: reason,
             account_size: 0,
@@ -429,6 +430,18 @@ impl LoadedPrograms {
 
                             if current_slot >= entry.effective_slot {
                                 return Some((key, entry.clone()));
+                            } else if entry.effective_slot.saturating_sub(entry.deployment_slot)
+                                == DELAY_VISIBILITY_SLOT_OFFSET
+                                && current_slot >= entry.deployment_slot
+                            {
+                                // Found a program entry on the current fork, but it's not effective
+                                // yet. It indicates that the program has delayed visibility. Return
+                                // the tombstone to reflect that.
+                                let delay_visibility = LoadedProgram::new_tombstone(
+                                    entry.deployment_slot,
+                                    LoadedProgramType::DelayVisibility,
+                                );
+                                return Some((key, Arc::new(delay_visibility)));
                             }
                         }
                     }
@@ -533,7 +546,7 @@ mod tests {
     use {
         crate::loaded_programs::{
             BlockRelation, ForkGraph, LoadedProgram, LoadedProgramMatchCriteria, LoadedProgramType,
-            LoadedPrograms, LoadedProgramsForTxBatch, WorkingSlot,
+            LoadedPrograms, LoadedProgramsForTxBatch, WorkingSlot, DELAY_VISIBILITY_SLOT_OFFSET,
         },
         percentage::Percentage,
         solana_rbpf::vm::BuiltInProgram,
@@ -1100,7 +1113,14 @@ mod tests {
 
         let program2 = Pubkey::new_unique();
         assert!(!cache.replenish(program2, new_test_loaded_program(5, 6)).0);
-        assert!(!cache.replenish(program2, new_test_loaded_program(11, 12)).0);
+        assert!(
+            !cache
+                .replenish(
+                    program2,
+                    new_test_loaded_program(11, 11 + DELAY_VISIBILITY_SLOT_OFFSET)
+                )
+                .0
+        );
 
         let program3 = Pubkey::new_unique();
         assert!(!cache.replenish(program3, new_test_loaded_program(25, 26)).0);
@@ -1109,7 +1129,14 @@ mod tests {
         assert!(!cache.replenish(program4, new_test_loaded_program(0, 1)).0);
         assert!(!cache.replenish(program4, new_test_loaded_program(5, 6)).0);
         // The following is a special case, where effective slot is 3 slots in the future
-        assert!(!cache.replenish(program4, new_test_loaded_program(15, 18)).0);
+        assert!(
+            !cache
+                .replenish(
+                    program4,
+                    new_test_loaded_program(15, 15 + DELAY_VISIBILITY_SLOT_OFFSET)
+                )
+                .0
+        );
 
         // Current fork graph
         //                   0
@@ -1146,7 +1173,7 @@ mod tests {
         assert!(missing.contains(&program3));
 
         // Testing fork 0 - 5 - 11 - 15 - 16 with current slot at 16
-        let mut working_slot = TestWorkingSlot::new(16, &[0, 5, 11, 15, 16, 18, 19, 23]);
+        let mut working_slot = TestWorkingSlot::new(15, &[0, 5, 11, 15, 16, 18, 19, 23]);
         let (found, missing) = cache.extract(
             &working_slot,
             vec![
@@ -1158,11 +1185,17 @@ mod tests {
             .into_iter(),
         );
 
-        assert!(match_slot(&found, &program1, 0, 16));
-        assert!(match_slot(&found, &program2, 11, 16));
+        assert!(match_slot(&found, &program1, 0, 15));
+        assert!(match_slot(&found, &program2, 11, 15));
 
         // The effective slot of program4 deployed in slot 15 is 19. So it should not be usable in slot 16.
-        assert!(match_slot(&found, &program4, 5, 16));
+        // A delay visibility tombstone should be returned here.
+        let tombstone = found.find(program4).expect("Failed to find the tombstone");
+        assert!(matches!(
+            tombstone.program,
+            LoadedProgramType::DelayVisibility
+        ));
+        assert_eq!(tombstone.deployment_slot, 15);
 
         assert!(missing.contains(&program3));
 
@@ -1222,7 +1255,13 @@ mod tests {
         );
 
         assert!(match_slot(&found, &program1, 0, 11));
-        assert!(match_slot(&found, &program2, 5, 11));
+        // program2 was updated at slot 11, but is not effective till slot 12. The result should contain a tombstone.
+        let tombstone = found.find(program2).expect("Failed to find the tombstone");
+        assert!(matches!(
+            tombstone.program,
+            LoadedProgramType::DelayVisibility
+        ));
+        assert_eq!(tombstone.deployment_slot, 11);
         assert!(match_slot(&found, &program4, 5, 11));
 
         assert!(missing.contains(&program3));