Add utility functions for testing (#10749)

* Add ancestor iterator

* Add blockstore generation from trees

Co-authored-by: Carl <carl@solana.com>

Cargo.lock

@@ -4199,6 +4199,7 @@ dependencies = [
  "solana-vote-program",
  "tempfile",
  "thiserror",
+ "trees",
 ]
 
 [[package]]

ledger/Cargo.toml

@@ -43,6 +43,7 @@ solana-stake-program = { path = "../programs/stake", version = "1.3.0" }
 solana-vote-program = { path = "../programs/vote", version = "1.3.0" }
 tempfile = "3.1.0"
 thiserror = "1.0"
+trees = "0.2.1"
 
 [dependencies.rocksdb]
 # Avoid the vendored bzip2 within rocksdb-sys that can cause linker conflicts

ledger/src/ancestor_iterator.rs

@@ -0,0 +1,116 @@
+use crate::blockstore::*;
+use solana_sdk::clock::Slot;
+
+pub struct AncestorIterator<'a> {
+    current: Option<Slot>,
+    blockstore: &'a Blockstore,
+}
+
+impl<'a> AncestorIterator<'a> {
+    pub fn new(start_slot: Slot, blockstore: &'a Blockstore) -> Self {
+        let current = blockstore.meta(start_slot).unwrap().and_then(|slot_meta| {
+            if slot_meta.is_parent_set() && start_slot != 0 {
+                Some(slot_meta.parent_slot)
+            } else {
+                None
+            }
+        });
+        Self {
+            current,
+            blockstore,
+        }
+    }
+}
+impl<'a> Iterator for AncestorIterator<'a> {
+    type Item = Slot;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let current = self.current.clone();
+        current.map(|slot| {
+            if slot != 0 {
+                self.current = self.blockstore.meta(slot).unwrap().and_then(|slot_meta| {
+                    if slot_meta.is_parent_set() {
+                        Some(slot_meta.parent_slot)
+                    } else {
+                        None
+                    }
+                });
+            } else {
+                self.current = None;
+            }
+            slot
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::blockstore_processor::fill_blockstore_slot_with_ticks;
+    use solana_sdk::hash::Hash;
+
+    #[test]
+    fn test_ancestor_iterator() {
+        let blockstore_path = get_tmp_ledger_path!();
+        let blockstore = Blockstore::open(&blockstore_path).unwrap();
+        blockstore.set_roots(&[0]).unwrap();
+        let ticks_per_slot = 5;
+
+        /*
+            Build a blockstore in the ledger with the following fork structure:
+
+                 slot 0
+                   |
+                 slot 1
+                 /   \
+            slot 2   |
+               /     |
+            slot 3   |
+                     |
+                   slot 4
+
+        */
+
+        // Fork 1, ending at slot 3
+        let last_entry_hash = Hash::default();
+        let fork_point = 1;
+        let mut fork_hash = Hash::default();
+        for slot in 0..=3 {
+            let parent = {
+                if slot == 0 {
+                    0
+                } else {
+                    slot - 1
+                }
+            };
+            let last_entry_hash = fill_blockstore_slot_with_ticks(
+                &blockstore,
+                ticks_per_slot,
+                slot,
+                parent,
+                last_entry_hash,
+            );
+
+            if slot == fork_point {
+                fork_hash = last_entry_hash;
+            }
+        }
+
+        // Fork 2, ending at slot 4
+        let _ =
+            fill_blockstore_slot_with_ticks(&blockstore, ticks_per_slot, 4, fork_point, fork_hash);
+
+        // Test correctness
+        assert!(AncestorIterator::new(0, &blockstore)
+            .collect::<Vec<Slot>>()
+            .is_empty());
+        assert_eq!(
+            AncestorIterator::new(4, &blockstore).collect::<Vec<Slot>>(),
+            vec![1, 0]
+        );
+        assert_eq!(
+            AncestorIterator::new(3, &blockstore).collect::<Vec<Slot>>(),
+            vec![2, 1, 0]
+        );
+    }
+}

ledger/src/blockstore.rs

@@ -55,6 +55,7 @@ use std::{
     },
     time::Duration,
 };
+use trees::{Tree, TreeWalk};
 
 pub mod blockstore_purge;
 
@@ -303,6 +304,23 @@ impl Blockstore {
         Ok((blockstore, signal_receiver, completed_slots_receiver))
     }
 
+    pub fn add_tree(&self, forks: Tree<Slot>, is_orphan: bool) {
+        let mut walk = TreeWalk::from(forks);
+        while let Some(visit) = walk.get() {
+            let slot = visit.node().data;
+            if self.meta(slot).unwrap().is_some() {
+                walk.forward();
+                continue;
+            }
+            let parent = walk.get_parent().map(|n| n.data);
+            if parent.is_some() || !is_orphan {
+                let (shreds, _) = make_slot_entries(slot, parent.unwrap_or(slot), 1);
+                self.insert_shreds(shreds, None, false).unwrap();
+            }
+            walk.forward();
+        }
+    }
+
     pub fn set_no_compaction(&mut self, no_compaction: bool) {
         self.no_compaction = no_compaction;
     }