opt cache impl

Author: Lchangliang

be/src/olap/tablet_schema_cache.h

@@ -18,10 +18,9 @@
 #pragma once
 
 #include <gen_cpp/olap_file.pb.h>
+#include <parallel_hashmap/phmap.h>
 
 #include <memory>
-#include <mutex>
-#include <unordered_map>
 
 #include "olap/tablet_schema.h"
 
@@ -37,26 +36,23 @@ class TabletSchemaCache {
 
     static TabletSchemaCache* instance() { return _s_instance; }
 
-    std::shared_ptr<TabletSchema> insert(const std::string& key) {
-        std::lock_guard guard(_mtx);
-        auto iter = _cache.find(key);
-        if (iter == _cache.end()) {
-            TabletSchemaPB tablet_schema_pb;
-            tablet_schema_pb.ParseFromString(key);
-            std::shared_ptr<TabletSchema> value = std::make_shared<TabletSchema>();
-            value->init_from_pb(tablet_schema_pb);
-            _cache[key] = value;
-            return value;
-        } else {
-            return iter->second;
-        }
+    TabletSchemaSPtr insert(const std::string& key) {
+        TabletSchemaSPtr res;
+        _cache.lazy_emplace_l(
+                key, [&](const TabletSchemaSPtr& tablet_schema) { res = tablet_schema; },
+                [&](const auto& ctor) {
+                    TabletSchemaPB tablet_schema_pb;
+                    tablet_schema_pb.ParseFromString(key);
+                    res = std::make_shared<TabletSchema>();
+                    res->init_from_pb(tablet_schema_pb);
+                    ctor(key, res);
+                });
+        return res;
     }
 
 private:
     static inline TabletSchemaCache* _s_instance = nullptr;
-
-    std::unordered_map<std::string, TabletSchemaSPtr> _cache;
-    std::mutex _mtx;
+    phmap::parallel_flat_hash_map<std::string, TabletSchemaSPtr> _cache;
 };
 
 } // namespace doris