db: cache chain config in local kv::api

Author: battlmonstr

silkworm/db/chain/local_chain_storage.cpp

@@ -23,8 +23,18 @@
 
 namespace silkworm::db::chain {
 
+LocalChainStorage::LocalChainStorage(
+    db::DataModel data_model,
+    std::shared_ptr<Cache> cache)
+    : data_model_{data_model},
+      cache_{cache} {
+    std::call_once(cache_->chain_config_once_flag, [this] {
+        cache_->chain_config = data_model_.read_chain_config();
+    });
+}
+
 Task<ChainConfig> LocalChainStorage::read_chain_config() const {
-    const auto chain_config{data_model_.read_chain_config()};
+    const auto chain_config = cache_->chain_config;
     if (!chain_config) {
         throw std::runtime_error{"empty chain config data in storage"};
     }

silkworm/db/chain/local_chain_storage.hpp

@@ -16,6 +16,8 @@
 
 #pragma once
 
+#include <mutex>
+
 #include <silkworm/db/access_layer.hpp>
 
 #include "chain_storage.hpp"
@@ -26,8 +28,14 @@ namespace silkworm::db::chain {
 //! in local database (accessed via MDBX API) or local snapshot files (accessed via custom snapshot API)
 class LocalChainStorage : public ChainStorage {
   public:
-    explicit LocalChainStorage(db::DataModel data_model)
-        : data_model_{data_model} {}
+    struct Cache {
+        std::optional<ChainConfig> chain_config;
+        std::once_flag chain_config_once_flag;
+    };
+
+    LocalChainStorage(
+        db::DataModel data_model,
+        std::shared_ptr<Cache> cache);
     ~LocalChainStorage() override = default;
 
     Task<ChainConfig> read_chain_config() const override;
@@ -74,6 +82,7 @@ class LocalChainStorage : public ChainStorage {
 
   private:
     db::DataModel data_model_;
+    std::shared_ptr<Cache> cache_;
 };
 
 }  // namespace silkworm::db::chain

silkworm/db/kv/api/direct_service.cpp

@@ -25,7 +25,8 @@ namespace silkworm::db::kv::api {
 
 DirectService::DirectService(ServiceRouter router, DataStoreRef data_store)
     : router_{router},
-      data_store_{std::move(data_store)} {}
+      data_store_{std::move(data_store)},
+      shared_transaction_cache_{std::make_shared<LocalTransaction::Cache>()} {}
 
 // rpc Version(google.protobuf.Empty) returns (types.VersionReply);
 Task<Version> DirectService::version() {
@@ -34,7 +35,7 @@ Task<Version> DirectService::version() {
 
 // rpc Tx(stream Cursor) returns (stream Pair);
 Task<std::unique_ptr<Transaction>> DirectService::begin_transaction() {
-    co_return std::make_unique<LocalTransaction>(data_store_);
+    co_return std::make_unique<LocalTransaction>(data_store_, shared_transaction_cache_);
 }
 
 // rpc StateChanges(StateChangeRequest) returns (stream StateChangeBatch);

silkworm/db/kv/api/direct_service.hpp

@@ -18,6 +18,7 @@
 
 #include <silkworm/db/data_store.hpp>
 
+#include "local_transaction.hpp"
 #include "service.hpp"
 #include "service_router.hpp"
 
@@ -51,6 +52,8 @@ class DirectService : public Service {
 
     //! The data store
     DataStoreRef data_store_;
+
+    std::shared_ptr<LocalTransaction::Cache> shared_transaction_cache_;
 };
 
 }  // namespace silkworm::db::kv::api

silkworm/db/kv/api/local_transaction.cpp

@@ -138,7 +138,9 @@ Task<std::shared_ptr<CursorDupSort>> LocalTransaction::get_cursor(const std::str
 
 std::shared_ptr<chain::ChainStorage> LocalTransaction::create_storage() {
     // The calling thread *must* be the *same* which created this LocalTransaction instance
-    return std::make_shared<chain::LocalChainStorage>(DataModel{tx_, data_store_.blocks_repository});
+    return std::make_shared<chain::LocalChainStorage>(
+        DataModel{tx_, data_store_.blocks_repository},
+        cache_->chain_storage_cache());
 }
 
 Task<TxnId> LocalTransaction::first_txn_num_in_block(BlockNum block_num) {

silkworm/db/kv/api/local_transaction.hpp

@@ -24,6 +24,7 @@
 
 #include <silkworm/infra/concurrency/task.hpp>
 
+#include <silkworm/db/chain/local_chain_storage.hpp>
 #include <silkworm/db/data_store.hpp>
 
 #include "base_transaction.hpp"
@@ -34,8 +35,21 @@ namespace silkworm::db::kv::api {
 
 class LocalTransaction : public BaseTransaction {
   public:
-    explicit LocalTransaction(DataStoreRef data_store)
+    class Cache {
+      public:
+        using ChainStorageCache = db::chain::LocalChainStorage::Cache;
+        Cache() : chain_storage_cache_{std::make_shared<ChainStorageCache>()} {}
+        std::shared_ptr<ChainStorageCache> chain_storage_cache() const { return chain_storage_cache_; }
+
+      private:
+        std::shared_ptr<ChainStorageCache> chain_storage_cache_;
+    };
+
+    LocalTransaction(
+        DataStoreRef data_store,
+        std::shared_ptr<Cache> cache)
         : data_store_{std::move(data_store)},
+          cache_{std::move(cache)},
           tx_{data_store_.chaindata.access_ro().start_ro_tx()} {}
 
     ~LocalTransaction() override = default;
@@ -104,6 +118,7 @@ class LocalTransaction : public BaseTransaction {
     std::map<std::string, std::shared_ptr<CursorDupSort>> dup_cursors_;
 
     DataStoreRef data_store_;
+    std::shared_ptr<Cache> cache_;
     uint32_t last_cursor_id_{0};
     datastore::kvdb::ROTxnManaged tx_;
     uint64_t tx_id_{++next_tx_id_};