add blobs cache and fix some block production

beacon_node/beacon_chain/src/blob_cache.rs

@@ -0,0 +1,32 @@
+use lru::LruCache;
+use parking_lot::Mutex;
+use tree_hash::TreeHash;
+use types::{BlobsSidecar, EthSpec, ExecutionPayload, Hash256};
+
+pub const DEFAULT_BLOB_CACHE_SIZE: usize = 10;
+
+/// A cache blobs by beacon block root.
+pub struct BlobCache<T: EthSpec> {
+    blobs: Mutex<LruCache<BlobCacheId, BlobsSidecar<T>>>,
+}
+
+#[derive(Hash, PartialEq, Eq)]
+struct BlobCacheId(Hash256);
+
+impl<T: EthSpec> Default for BlobCache<T> {
+    fn default() -> Self {
+        BlobCache {
+            blobs: Mutex::new(LruCache::new(DEFAULT_BLOB_CACHE_SIZE)),
+        }
+    }
+}
+
+impl<T: EthSpec> BlobCache<T> {
+    pub fn put(&self, beacon_block: Hash256, blobs: BlobsSidecar<T>) -> Option<BlobsSidecar<T>> {
+        self.blobs.lock().put(BlobCacheId(beacon_block), blobs)
+    }
+
+    pub fn pop(&self, root: &Hash256) -> Option<BlobsSidecar<T>> {
+        self.blobs.lock().pop(&BlobCacheId(*root))
+    }
+}