Add progress on test rig

beacon_node/beacon_chain/src/block_graph.rs

@@ -0,0 +1,37 @@
+use crate::{BeaconChain, CheckPoint, ClientDB, SlotClock};
+use std::collections::HashSet;
+use std::sync::{RwLock, RwLockReadGuard};
+use types::{BeaconBlock, BeaconState, Hash256};
+
+pub struct BlockGraph {
+    pub leaves: RwLock<HashSet<Hash256>>,
+}
+
+impl BlockGraph {
+    pub fn new() -> Self {
+        Self {
+            leaves: RwLock::new(HashSet::new()),
+        }
+    }
+    /// Add a new leaf to the block hash graph. Returns `true` if the leaf was built upon another
+    /// leaf.
+    pub fn add_leaf(&self, parent: &Hash256, leaf: Hash256) -> bool {
+        let mut leaves = self
+            .leaves
+            .write()
+            .expect("CRITICAL: BlockGraph poisioned.");
+
+        if leaves.contains(parent) {
+            leaves.remove(parent);
+            leaves.insert(leaf);
+            true
+        } else {
+            leaves.insert(leaf);
+            false
+        }
+    }
+
+    pub fn leaves(&self) -> RwLockReadGuard<HashSet<Hash256>> {
+        self.leaves.read().expect("CRITICAL: BlockGraph poisioned.")
+    }
+}