feat: add metric for storage reads of missing contracts (#12317)

core/primitives/src/errors.rs

@@ -100,6 +100,17 @@ pub enum MissingTrieValueContext {
     TrieStorage,
 }
 
+impl MissingTrieValueContext {
+    pub fn metrics_label(&self) -> &str {
+        match self {
+            Self::TrieIterator => "trie_iterator",
+            Self::TriePrefetchingStorage => "trie_prefetching_storage",
+            Self::TrieMemoryPartialStorage => "trie_memory_partial_storage",
+            Self::TrieStorage => "trie_storage",
+        }
+    }
+}
+
 /// Errors which may occur during working with trie storages, storing
 /// trie values (trie nodes and state values) by their hashes.
 #[derive(

core/store/src/contract.rs

@@ -1,4 +1,5 @@
-use crate::TrieStorage;
+use crate::{metrics, TrieStorage};
+use near_primitives::errors::StorageError;
 use near_primitives::hash::CryptoHash;
 use near_primitives::stateless_validation::contract_distribution::CodeHash;
 use near_vm_runner::ContractCode;
@@ -124,6 +125,12 @@ impl ContractStorage {
 
         match self.storage.retrieve_raw_bytes(&code_hash) {
             Ok(raw_code) => Some(ContractCode::new(raw_code.to_vec(), Some(code_hash))),
+            Err(StorageError::MissingTrieValue(context, _)) => {
+                metrics::STORAGE_MISSING_CONTRACTS_COUNT
+                    .with_label_values(&[context.metrics_label()])
+                    .inc();
+                None
+            }
             Err(_) => None,
         }
     }

core/store/src/metrics.rs

@@ -561,6 +561,16 @@ pub static TRIE_MEMORY_PARTIAL_STORAGE_MISSING_VALUES_COUNT: LazyLock<IntCounter
         .unwrap()
     });
 
+/// This metrics is useful to track witness contract distribution failures.
+pub static STORAGE_MISSING_CONTRACTS_COUNT: LazyLock<IntCounterVec> = LazyLock::new(|| {
+    try_create_int_counter_vec(
+        "near_storage_missing_contracts_count",
+        "Number of contract reads from storage resulted in MissingTrieValue error",
+        &["context"],
+    )
+    .unwrap()
+});
+
 fn export_store_stats(store: &Store, temperature: Temperature) {
     if let Some(stats) = store.get_store_statistics() {
         tracing::debug!(target:"metrics", "Exporting the db metrics for {temperature:?} store.");