1 files changed, 69 insertions, 15 deletions
diff --git a/library/cpp/logger/sync_page_cache_file.cpp b/library/cpp/logger/sync_page_cache_file.cpp
index 1424159af7..7f262c7ee7 100644
--- a/library/cpp/logger/sync_page_cache_file.cpp
+++ b/library/cpp/logger/sync_page_cache_file.cpp
@@ -1,26 +1,44 @@
 #include "sync_page_cache_file.h"
+
 #include "record.h"
 
 #include <util/generic/buffer.h>
 #include <util/generic/yexception.h>
+#include <util/system/align.h>
+#include <util/system/event.h>
 #include <util/system/file.h>
 #include <util/system/info.h>
 #include <util/system/mutex.h>
-#include <util/system/align.h>
+#include <util/system/thread.h>
 
 class TSyncPageCacheFileLogBackend::TImpl: public TNonCopyable {
 public:
-    TImpl(const TString& path, size_t maxBufferSize, size_t maxPendingCacheSize)
+    TImpl(
+        const TString& path,
+        size_t maxBufferSize,
+        size_t maxPendingCacheSize,
+        TMaybe<TDuration> bufferFlushPeriod
+    )
         : File_{OpenFile(path)}
         , MaxBufferSize_{maxBufferSize}
         , MaxPendingCacheSize_{maxPendingCacheSize}
         , Buffer_{maxBufferSize}
+        , BufferFlushPeriod_{bufferFlushPeriod}
     {
         ResetPtrs();
+
+        if (BufferFlushPeriod_) {
+            BufferFlushThreadPtr_ = MakeHolder<TThread>([this] {RunBufferFlushThread();});
+            BufferFlushThreadPtr_->Start();
+        }
     }
 
     ~TImpl() noexcept {
         try {
+            if (BufferFlushThreadPtr_) {
+                BufferFlushThreadExitWaiter_.Signal();
+            }
+
             Write();
             FlushSync(GuaranteedWrittenPtr_, WrittenPtr_);
         } catch (...) {
@@ -32,17 +50,7 @@ public:
 
         Buffer_.Append(rec.Data, rec.Len);
         if (Buffer_.size() >= MaxBufferSize_) {
-            const i64 prevAlignedEndPtr = PageAlignedWrittenPtr_;
-            Write();
-
-            if (prevAlignedEndPtr < PageAlignedWrittenPtr_) {
-                FlushAsync(prevAlignedEndPtr, PageAlignedWrittenPtr_);
-            }
-
-            const i64 minPendingCacheOffset = PageAlignedWrittenPtr_ - MaxPendingCacheSize_;
-            if (minPendingCacheOffset > GuaranteedWrittenPtr_) {
-                FlushSync(GuaranteedWrittenPtr_, minPendingCacheOffset);
-            }
+            WriteAndFlush();
         }
     }
 
@@ -101,6 +109,36 @@ private:
         GuaranteedWrittenPtr_ = to;
     }
 
+    void WriteAndFlush() {
+        const i64 prevAlignedEndPtr = PageAlignedWrittenPtr_;
+        Write();
+
+        if (prevAlignedEndPtr < PageAlignedWrittenPtr_) {
+            FlushAsync(prevAlignedEndPtr, PageAlignedWrittenPtr_);
+        }
+
+        const i64 minPendingCacheOffset = PageAlignedWrittenPtr_ - MaxPendingCacheSize_;
+        if (minPendingCacheOffset > GuaranteedWrittenPtr_) {
+            FlushSync(GuaranteedWrittenPtr_, minPendingCacheOffset);
+        }
+    }
+
+    void RunBufferFlushThread() {
+        Y_ENSURE(BufferFlushPeriod_);
+        TInstant deadline;
+        do {
+            deadline = TInstant::Now() + *BufferFlushPeriod_;
+            try {
+                TGuard guard{Lock_};
+                if (!Buffer_.Empty()) {
+                    WriteAndFlush();
+                }
+            } catch (...) {
+                Cerr << "Failed to flush eventlog buffer: " << CurrentExceptionMessage() << Endl;
+            }
+        } while (!BufferFlushThreadExitWaiter_.WaitD(deadline));
+    }
+
 private:
     TMutex Lock_;
     TFile File_;
@@ -112,10 +150,26 @@ private:
     i64 WrittenPtr_ = 0;
     i64 PageAlignedWrittenPtr_ = 0;
     i64 GuaranteedWrittenPtr_ = 0;
+
+    const TMaybe<TDuration> BufferFlushPeriod_;
+    TManualEvent BufferFlushThreadExitWaiter_;
+
+    // thread should be declared last to be destroyed before other props
+    THolder<TThread> BufferFlushThreadPtr_;
 };
 
-TSyncPageCacheFileLogBackend::TSyncPageCacheFileLogBackend(const TString& path, size_t maxBufferSize, size_t maxPengingCacheSize)
-    : Impl_(MakeHolder<TImpl>(path, maxBufferSize, maxPengingCacheSize))
+TSyncPageCacheFileLogBackend::TSyncPageCacheFileLogBackend(
+    const TString& path,
+    size_t maxBufferSize,
+    size_t maxPengingCacheSize,
+    TMaybe<TDuration> bufferFlushPeriod
+)
+    : Impl_(MakeHolder<TImpl>(
+        path,
+        maxBufferSize,
+        maxPengingCacheSize,
+        bufferFlushPeriod
+    ))
 {}
 
 TSyncPageCacheFileLogBackend::~TSyncPageCacheFileLogBackend() {