bug cache: don't write cache metrics before cache component is initialized

commit_hash:d790496a4cffc26f738fdc382251ea6ad8a829de

Author: Anton3

core/include/userver/cache/cache_statistics.hpp

@@ -37,6 +37,7 @@ struct Statistics final {
     UpdateStatistics full_update;
     UpdateStatistics incremental_update;
     std::atomic<std::size_t> documents_current_count{0};
+    std::atomic<bool> is_first_sync_update_complete{false};  // Success or failure does not matter here.
 };
 
 void DumpMetric(utils::statistics::Writer& writer, const Statistics& stats);

core/src/cache/cache_statistics.cpp

@@ -76,6 +76,10 @@ void DumpMetric(utils::statistics::Writer& writer, const UpdateStatistics& stats
 }
 
 void DumpMetric(utils::statistics::Writer& writer, const Statistics& stats) {
+    if (!stats.is_first_sync_update_complete) {
+        return;
+    }
+
     const auto& full = stats.full_update;
     const auto& incremental = stats.incremental_update;
     UpdateStatistics any;

core/src/cache/cache_update_trait_impl.cpp

@@ -214,6 +214,8 @@ void CacheUpdateTrait::Impl::StartPeriodicUpdates(utils::Flags<CacheUpdateTrait:
             }
         }
 
+        statistics_.is_first_sync_update_complete = true;
+
         if (dump_time && config->first_update_type == FirstUpdateType::kIncrementalThenAsyncFull) {
             dump_first_update_type_ = UpdateType::kFull;
             periodic_task_flags_ |= utils::PeriodicTask::Flags::kNow;