Introduce message_level_overrides to tune log message levels at runtime

* Changelog entry
Type: feature

Add message_level_overrides option to logging config for better run-time tuning.
commit_hash:07e9563fd111c437edf7ac0e5dd190781878d8fa

3 files changed, 35 insertions, 20 deletions

diff --git a/library/cpp/yt/logging/backends/stream/stream_log_manager.cpp b/library/cpp/yt/logging/backends/stream/stream_log_manager.cpp
index 62269dc0c0..62fa3e91d0 100644
--- a/library/cpp/yt/logging/backends/stream/stream_log_manager.cpp
+++ b/library/cpp/yt/logging/backends/stream/stream_log_manager.cpp
@@ -28,10 +28,8 @@ public:
         anchor->Registered = true;
     }
 
-    virtual void UpdateAnchor(TLoggingAnchor* anchor) override
-    {
-        anchor->Enabled = true;
-    }
+    virtual void UpdateAnchor(TLoggingAnchor* /*anchor*/) override
+    { }
 
     virtual void Enqueue(TLogEvent&& event) override
     {
diff --git a/library/cpp/yt/logging/logger-inl.h b/library/cpp/yt/logging/logger-inl.h
index f3993a4c48..f1be10827f 100644
--- a/library/cpp/yt/logging/logger-inl.h
+++ b/library/cpp/yt/logging/logger-inl.h
@@ -14,11 +14,11 @@ namespace NYT::NLogging {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-inline bool TLogger::IsAnchorUpToDate(const TLoggingAnchor& position) const
+inline bool TLogger::IsAnchorUpToDate(const TLoggingAnchor& anchor) const
 {
     return
         !Category_ ||
-        position.CurrentVersion == Category_->ActualVersion->load(std::memory_order::relaxed);
+        anchor.CurrentVersion == Category_->ActualVersion->load(std::memory_order::relaxed);
 }
 
 template <class... TArgs>
@@ -49,6 +49,17 @@ TLogger TLogger::WithStructuredTag(TStringBuf key, TType value) const
     return result;
 }
 
+Y_FORCE_INLINE ELogLevel TLogger::GetEffectiveLoggingLevel(ELogLevel level, const TLoggingAnchor& anchor)
+{
+    // Check if anchor is suppressed.
+    if (anchor.Suppressed.load(std::memory_order::relaxed)) {
+        return ELogLevel::Minimum;
+    }
+
+    // Compute the actual level taking anchor override into account.
+    return anchor.LevelOverride.load(std::memory_order::relaxed).value_or(level);
+}
+
 Y_FORCE_INLINE bool TLogger::IsLevelEnabled(ELogLevel level) const
 {
     // This is the first check which is intended to be inlined next to
diff --git a/library/cpp/yt/logging/logger.h b/library/cpp/yt/logging/logger.h
index 4f0ed44ab7..35aba4eb4c 100644
--- a/library/cpp/yt/logging/logger.h
+++ b/library/cpp/yt/logging/logger.h
@@ -47,12 +47,17 @@ struct TLoggingCategory
 struct TLoggingAnchor
 {
     std::atomic<bool> Registered = false;
+    TLoggingAnchor* NextAnchor = nullptr;
+
     ::TSourceLocation SourceLocation = {TStringBuf{}, 0};
     TString AnchorMessage;
-    TLoggingAnchor* NextAnchor = nullptr;
 
     std::atomic<int> CurrentVersion = 0;
-    std::atomic<bool> Enabled = false;
+
+    std::atomic<bool> Suppressed = false;
+
+    std::atomic<std::optional<ELogLevel>> LevelOverride;
+    static_assert(decltype(LevelOverride)::is_always_lock_free);
 
     struct TCounter
     {
@@ -189,6 +194,9 @@ public:
 
     const TLoggingCategory* GetCategory() const;
 
+    //! Combines given #level and the override from #anchor.
+    static ELogLevel GetEffectiveLoggingLevel(ELogLevel level, const TLoggingAnchor& anchor);
+
     //! Validate that level is admitted by logger's own min level
     //! and by category's min level.
     bool IsLevelEnabled(ELogLevel level) const;
@@ -300,40 +308,38 @@ void LogStructuredEvent(
     do { \
         const auto& logger__ = (logger)(); \
         auto level__ = (level); \
-        \
-        if (!logger__.IsLevelEnabled(level__)) { \
-            break; \
-        } \
-        \
         auto location__ = __LOCATION__; \
         \
         ::NYT::NLogging::TLoggingAnchor* anchor__ = (anchor); \
-        if (!anchor__) { \
+        [[unlikely]] if (!anchor__) { \
             static ::NYT::TLeakyStorage<::NYT::NLogging::TLoggingAnchor> staticAnchor__; \
             anchor__ = staticAnchor__.Get(); \
         } \
         \
         bool anchorUpToDate__ = logger__.IsAnchorUpToDate(*anchor__); \
-        if (anchorUpToDate__ && !anchor__->Enabled.load(std::memory_order::relaxed)) { \
-            break; \
+        [[likely]] if (anchorUpToDate__) { \
+            auto effectiveLevel__ = ::NYT::NLogging::TLogger::GetEffectiveLoggingLevel(level__, *anchor__); \
+            if (!logger__.IsLevelEnabled(effectiveLevel__)) { \
+                break; \
+            } \
         } \
         \
         auto loggingContext__ = ::NYT::NLogging::GetLoggingContext(); \
         auto message__ = ::NYT::NLogging::NDetail::BuildLogMessage(loggingContext__, logger__, __VA_ARGS__); \
         \
-        if (!anchorUpToDate__) { \
+        [[unlikely]] if (!anchorUpToDate__) { \
             logger__.RegisterStaticAnchor(anchor__, location__, message__.Anchor); \
-            logger__.UpdateAnchor(anchor__); \
         } \
         \
-        if (!anchor__->Enabled.load(std::memory_order::relaxed)) { \
+        auto effectiveLevel__ = ::NYT::NLogging::TLogger::GetEffectiveLoggingLevel(level__, *anchor__); \
+        if (!logger__.IsLevelEnabled(effectiveLevel__)) { \
             break; \
         } \
         \
         ::NYT::NLogging::NDetail::LogEventImpl( \
             loggingContext__, \
             logger__, \
-            level__, \
+            effectiveLevel__, \
             location__, \
             anchor__, \
             std::move(message__.MessageRef)); \