fix duplicate UUIDs of LiveView on server startup

src/Interpreters/Context.cpp

@@ -26,7 +26,6 @@
 #include <Storages/MergeTree/MergeTreeSettings.h>
 #include <Storages/CompressionCodecSelector.h>
 #include <Storages/StorageS3Settings.h>
-#include <Storages/LiveView/TemporaryLiveViewCleaner.h>
 #include <Disks/DiskLocal.h>
 #include <TableFunctions/TableFunctionFactory.h>
 #include <Interpreters/ActionLocksManager.h>
@@ -429,7 +428,6 @@ struct ContextShared
         if (system_logs)
             system_logs->shutdown();
 
-        TemporaryLiveViewCleaner::shutdown();
         DatabaseCatalog::shutdown();
 
         /// Preemptive destruction is important, because these objects may have a refcount to ContextShared (cyclic reference).
@@ -493,7 +491,6 @@ Context Context::createGlobal(ContextShared * shared)
 void Context::initGlobal()
 {
     DatabaseCatalog::init(*this);
-    TemporaryLiveViewCleaner::init(*this);
 }
 
 SharedContextHolder Context::createShared()

src/Interpreters/DatabaseCatalog.cpp

@@ -8,6 +8,7 @@
 #include <Poco/File.h>
 #include <Common/quoteString.h>
 #include <Storages/StorageMemory.h>
+#include <Storages/LiveView/TemporaryLiveViewCleaner.h>
 #include <Core/BackgroundSchedulePool.h>
 #include <Parsers/formatAST.h>
 #include <IO/ReadHelpers.h>
@@ -148,10 +149,16 @@ void DatabaseCatalog::loadDatabases()
     std::lock_guard lock{tables_marked_dropped_mutex};
     if (!tables_marked_dropped.empty())
         (*drop_task)->schedule();
+
+    /// Another background thread which drops temporary LiveViews.
+    /// We should start it after loadMarkedAsDroppedTables() to avoid race condition.
+    TemporaryLiveViewCleaner::instance().startupIfNecessary();
 }
 
 void DatabaseCatalog::shutdownImpl()
 {
+    TemporaryLiveViewCleaner::shutdown();
+
     if (drop_task)
         (*drop_task)->deactivate();
 
@@ -524,6 +531,7 @@ std::unique_ptr<DatabaseCatalog> DatabaseCatalog::database_catalog;
 DatabaseCatalog::DatabaseCatalog(Context & global_context_)
     : global_context(global_context_), log(&Poco::Logger::get("DatabaseCatalog"))
 {
+    TemporaryLiveViewCleaner::init(global_context);
 }
 
 DatabaseCatalog & DatabaseCatalog::init(Context & global_context_)

src/Storages/LiveView/TemporaryLiveViewCleaner.cpp

@@ -48,6 +48,37 @@ void TemporaryLiveViewCleaner::init(Context & global_context_)
     the_instance.reset(new TemporaryLiveViewCleaner(global_context_));
 }
 
+void TemporaryLiveViewCleaner::startupIfNecessary()
+{
+    std::lock_guard lock{mutex};
+    if (background_thread_should_exit)
+        return;
+    if (!views.empty())
+        startupIfNecessaryImpl(lock);
+}
+
+void TemporaryLiveViewCleaner::startupIfNecessaryImpl(const std::lock_guard<std::mutex> &)
+{
+    /// If views.empty() the background thread isn't running or it's going to stop right now.
+    /// If can_start_background_thread is false, then the thread has not been started previously.
+    bool background_thread_is_running;
+    if (can_start_background_thread)
+    {
+        background_thread_is_running = !views.empty();
+    }
+    else
+    {
+        can_start_background_thread = true;
+        background_thread_is_running = false;
+    }
+
+    if (!background_thread_is_running)
+    {
+        if (background_thread.joinable())
+            background_thread.join();
+        background_thread = ThreadFromGlobalPool{&TemporaryLiveViewCleaner::backgroundThreadFunc, this};
+    }
+}
 
 void TemporaryLiveViewCleaner::shutdown()
 {
@@ -79,20 +110,13 @@ void TemporaryLiveViewCleaner::addView(const std::shared_ptr<StorageLiveView> &
     if (background_thread_should_exit)
         return;
 
-    /// If views.empty() the background thread isn't running or it's going to stop right now.
+    if (can_start_background_thread)
-    bool background_thread_is_running = !views.empty();
+        startupIfNecessaryImpl(lock);
 
     /// Keep the vector `views` sorted by time of next check.
     StorageAndTimeOfCheck storage_and_time_of_check{view, time_of_next_check};
     views.insert(std::upper_bound(views.begin(), views.end(), storage_and_time_of_check), storage_and_time_of_check);
 
-    if (!background_thread_is_running)
-    {
-        if (background_thread.joinable())
-            background_thread.join();
-        background_thread = ThreadFromGlobalPool{&TemporaryLiveViewCleaner::backgroundThreadFunc, this};
-    }
-
     background_thread_wake_up.notify_one();
 }
 

src/Storages/LiveView/TemporaryLiveViewCleaner.h

@@ -23,6 +23,9 @@ public:
     static void init(Context & global_context_);
     static void shutdown();
 
+    void startupIfNecessary();
+    void startupIfNecessaryImpl(const std::lock_guard<std::mutex> &);
+
 private:
     friend std::unique_ptr<TemporaryLiveViewCleaner>::deleter_type;
 
@@ -44,6 +47,7 @@ private:
     std::mutex mutex;
     std::vector<StorageAndTimeOfCheck> views;
     ThreadFromGlobalPool background_thread;
+    bool can_start_background_thread = false;
     std::atomic<bool> background_thread_should_exit = false;
     std::condition_variable background_thread_wake_up;
 };