Add ability to change config reload interval

programs/keeper/Keeper.cpp

@@ -577,8 +577,7 @@ try
 #if USE_SSL
             CertificateReloader::instance().tryLoad(*config);
 #endif
-        },
+        });
-        /* already_loaded = */ false);  /// Reload it right now (initial loading)
 
     SCOPE_EXIT({
         LOG_INFO(log, "Shutting down.");

programs/server/Server.cpp

@@ -1690,8 +1690,7 @@ try
 
             /// Must be the last.
             latest_config = config;
-        },
+        });
-        /* already_loaded = */ false);  /// Reload it right now (initial loading)
 
     const auto listen_hosts = getListenHosts(config());
     const auto interserver_listen_hosts = getInterserverListenHosts(config());

src/Access/UsersConfigAccessStorage.cpp

@@ -880,8 +880,7 @@ void UsersConfigAccessStorage::load(
             Settings::checkNoSettingNamesAtTopLevel(*new_config, users_config_path);
             parseFromConfig(*new_config);
             access_control.getChangesNotifier().sendNotifications();
-        },
+        });
-        /* already_loaded = */ false);
 }
 
 void UsersConfigAccessStorage::startPeriodicReloading()

src/Common/Config/ConfigReloader.cpp

@@ -19,8 +19,7 @@ ConfigReloader::ConfigReloader(
         const std::string & preprocessed_dir_,
         zkutil::ZooKeeperNodeCache && zk_node_cache_,
         const zkutil::EventPtr & zk_changed_event_,
-        Updater && updater_,
+        Updater && updater_)
-        bool already_loaded)
     : config_path(config_path_)
     , extra_paths(extra_paths_)
     , preprocessed_dir(preprocessed_dir_)
@@ -28,10 +27,15 @@ ConfigReloader::ConfigReloader(
     , zk_changed_event(zk_changed_event_)
     , updater(std::move(updater_))
 {
-    if (!already_loaded)
+    auto config = reloadIfNewer(/* force = */ true, /* throw_on_error = */ true, /* fallback_to_preprocessed = */ true, /* initial_loading = */ true);
-        reloadIfNewer(/* force = */ true, /* throw_on_error = */ true, /* fallback_to_preprocessed = */ true, /* initial_loading = */ true);
-}
 
+    if (config.has_value())
+        reload_interval = std::chrono::milliseconds(config->configuration->getInt64("config_reload_interval_ms", DEFAULT_RELOAD_INTERVAL.count()));
+    else
+        reload_interval = DEFAULT_RELOAD_INTERVAL;
+
+    LOG_TRACE(log, "Config reload interval set to {}ms", reload_interval.count());
+}
 
 void ConfigReloader::start()
 {
@@ -82,7 +86,17 @@ void ConfigReloader::run()
             if (quit)
                 return;
 
-            reloadIfNewer(zk_changed, /* throw_on_error = */ false, /* fallback_to_preprocessed = */ false, /* initial_loading = */ false);
+            auto config = reloadIfNewer(zk_changed, /* throw_on_error = */ false, /* fallback_to_preprocessed = */ false, /* initial_loading = */ false);
+            if (config.has_value())
+            {
+                auto new_reload_interval = std::chrono::milliseconds(config->configuration->getInt64("config_reload_interval_ms", DEFAULT_RELOAD_INTERVAL.count()));
+                if (new_reload_interval != reload_interval)
+                {
+                    reload_interval = new_reload_interval;
+                    LOG_TRACE(log, "Config reload interval changed to {}ms", reload_interval.count());
+                }
+            }
+
         }
         catch (...)
         {
@@ -92,7 +106,7 @@ void ConfigReloader::run()
     }
 }
 
-void ConfigReloader::reloadIfNewer(bool force, bool throw_on_error, bool fallback_to_preprocessed, bool initial_loading)
+std::optional<ConfigProcessor::LoadedConfig> ConfigReloader::reloadIfNewer(bool force, bool throw_on_error, bool fallback_to_preprocessed, bool initial_loading)
 {
     std::lock_guard lock(reload_mutex);
 
@@ -120,7 +134,7 @@ void ConfigReloader::reloadIfNewer(bool force, bool throw_on_error, bool fallbac
                 throw;
 
             tryLogCurrentException(log, "ZooKeeper error when loading config from '" + config_path + "'");
-            return;
+            return std::nullopt;
         }
         catch (...)
         {
@@ -128,7 +142,7 @@ void ConfigReloader::reloadIfNewer(bool force, bool throw_on_error, bool fallbac
                 throw;
 
             tryLogCurrentException(log, "Error loading config from '" + config_path + "'");
-            return;
+            return std::nullopt;
         }
         config_processor.savePreprocessedConfig(loaded_config, preprocessed_dir);
 
@@ -154,11 +168,13 @@ void ConfigReloader::reloadIfNewer(bool force, bool throw_on_error, bool fallbac
             if (throw_on_error)
                 throw;
             tryLogCurrentException(log, "Error updating configuration from '" + config_path + "' config.");
-            return;
+            return std::nullopt;
         }
 
         LOG_DEBUG(log, "Loaded config '{}', performed update on configuration", config_path);
+        return loaded_config;
     }
+    return std::nullopt;
 }
 
 struct ConfigReloader::FileWithTimestamp

src/Common/Config/ConfigReloader.h

@@ -35,8 +35,7 @@ public:
         const std::string & preprocessed_dir,
         zkutil::ZooKeeperNodeCache && zk_node_cache,
         const zkutil::EventPtr & zk_changed_event,
-        Updater && updater,
+        Updater && updater);
-        bool already_loaded);
 
     ~ConfigReloader();
 
@@ -53,7 +52,7 @@ public:
 private:
     void run();
 
-    void reloadIfNewer(bool force, bool throw_on_error, bool fallback_to_preprocessed, bool initial_loading);
+    std::optional<ConfigProcessor::LoadedConfig> reloadIfNewer(bool force, bool throw_on_error, bool fallback_to_preprocessed, bool initial_loading);
 
     struct FileWithTimestamp;
 
@@ -67,7 +66,7 @@ private:
 
     FilesChangesTracker getNewFileList() const;
 
-    static constexpr auto reload_interval = std::chrono::seconds(2);
+    static constexpr auto DEFAULT_RELOAD_INTERVAL = std::chrono::milliseconds(2000);
 
     LoggerPtr log = getLogger("ConfigReloader");
 
@@ -85,6 +84,8 @@ private:
     std::atomic<bool> quit{false};
     ThreadFromGlobalPool thread;
 
+    std::chrono::milliseconds reload_interval = DEFAULT_RELOAD_INTERVAL;
+
     /// Locked inside reloadIfNewer.
     std::mutex reload_mutex;
 };

tests/integration/test_config_reloader_interval/__init__.py

@@ -0,0 +1 @@
+#!/usr/bin/env python3

tests/integration/test_config_reloader_interval/configs/config_reloader.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<clickhouse>
+  <config_reload_interval_ms>1000</config_reload_interval_ms>
+</clickhouse>

tests/integration/test_config_reloader_interval/test.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+import pytest
+import fnmatch
+
+from helpers.cluster import ClickHouseCluster
+from helpers.client import QueryRuntimeException
+
+cluster = ClickHouseCluster(__file__)
+
+node = cluster.add_instance(
+    "node",
+    main_configs=["configs/config_reloader.xml"],
+)
+
+
+@pytest.fixture(scope="module")
+def start_cluster():
+    try:
+        cluster.start()
+        yield cluster
+    finally:
+        cluster.shutdown()
+
+
+def test_reload_config(start_cluster):
+    assert node.wait_for_log_line(
+        f"Config reload interval set to 1000ms", look_behind_lines=2000
+    )
+
+    node.replace_in_config(
+        "/etc/clickhouse-server/config.d/config_reloader.xml",
+        "1000",
+        "7777",
+    )
+
+    assert node.wait_for_log_line(
+        f"Config reload interval changed to 7777ms", look_behind_lines=2000
+    )