From 1c3f5a3a9b5e99d5fa64147251aa25cab7f8ed8a Mon Sep 17 00:00:00 2001
From: Copilot <198982749+Copilot@users.noreply.github.com>
Date: Mon, 29 Sep 2025 23:32:33 +0200
Subject: [PATCH] Fix file flushing issue on ESP32 - implement configurable
 smart flushing policy (#22)

* Initial plan

* Implement smart file flushing policy for issue #21

Co-authored-by: jibrilsharafi <83494924+jibrilsharafi@users.noreply.github.com>

* Make flush log level configurable and add README documentation

Co-authored-by: jibrilsharafi <83494924+jibrilsharafi@users.noreply.github.com>

* Simplify flush configuration by removing FLUSH_ON_ERROR define

Co-authored-by: jibrilsharafi <83494924+jibrilsharafi@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jibrilsharafi <83494924+jibrilsharafi@users.noreply.github.com>
---
 README.md              | 12 ++++++++++++
 src/AdvancedLogger.cpp | 29 +++++++++++++++++++++++++++--
 src/AdvancedLogger.h   | 10 ++++++++++
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 04b7322..773c2dd 100644
--- a/README.md
+++ b/README.md
@@ -91,6 +91,18 @@ build_flags =
     -DADVANCED_LOGGER_MAX_MESSAGE_LENGTH=512
 ```
 
+### File Flushing
+Configure when log files are flushed to ensure data persistence:
+
+```cpp
+#define ADVANCED_LOGGER_FLUSH_INTERVAL_MS 5000        // Flush every 5 seconds (default)
+#define ADVANCED_LOGGER_FLUSH_LOG_LEVEL LogLevel::ERROR // Log level that triggers immediate flush (default)
+
+#include "AdvancedLogger.h"
+```
+
+The library automatically flushes files periodically and on the specified log level to prevent data loss during power cycles or crashes.
+
 ### Callbacks
 Register a function to handle log entries:
 
diff --git a/src/AdvancedLogger.cpp b/src/AdvancedLogger.cpp
index 797b5fb..f7a19ba 100644
--- a/src/AdvancedLogger.cpp
+++ b/src/AdvancedLogger.cpp
@@ -38,6 +38,9 @@ namespace AdvancedLogger
     static TaskHandle_t _logTaskHandle = nullptr;
     static bool _queueInitialized = false;
 
+    // File flushing control
+    static unsigned long _lastFlushTime = 0;
+
     // Forward declarations of private functions
     static void _log(const char *message, const char *file, const char *function, int line, LogLevel logLevel);
     static void _internalLog(const char* level, const char* format, ...);
@@ -142,6 +145,9 @@ namespace AdvancedLogger
         
         _logLines = getLogLines();
         
+        // Initialize flush timestamp
+        _lastFlushTime = millis();
+        
         _initLogQueue();
         
         _internalLog("DEBUG", "AdvancedLogger initialized");
@@ -331,7 +337,11 @@ namespace AdvancedLogger
 #endif
 
 #ifndef ADVANCED_LOGGER_DISABLE_FILE_LOGGING
-        if (entry.level >= _saveLevel) _save(messageFormatted);
+        if (entry.level >= _saveLevel) {
+            // Determine if immediate flush is needed based on log level
+            bool forceFlush = (entry.level >= ADVANCED_LOGGER_FLUSH_LOG_LEVEL);
+            _save(messageFormatted, forceFlush);
+        }
 #endif
     }
 
@@ -657,7 +667,21 @@ namespace AdvancedLogger
         if (!_checkAndOpenLogFile(FileMode::APPEND)) return;
 
         _logFile.println(messageFormatted);
-        if (flush) _logFile.flush();
+        
+        // Smart flushing logic
+        unsigned long currentTime = millis();
+        bool shouldFlush = flush;
+        
+        // Check if periodic flush interval has elapsed
+        if (!shouldFlush && (currentTime - _lastFlushTime >= ADVANCED_LOGGER_FLUSH_INTERVAL_MS)) {
+            shouldFlush = true;
+        }
+        
+        if (shouldFlush) {
+            _logFile.flush();
+            _lastFlushTime = currentTime;
+        }
+        
         _logLines++;
 
         if (_logLines >= _maxLogLines) {
@@ -830,6 +854,7 @@ namespace AdvancedLogger
     void _closeLogFile() 
     {
         if (_logFile) {
+            _logFile.flush(); // Ensure all data is written before closing
             _logFile.close();
             _currentFileMode = FileMode::APPEND; // Reset to default
         }
diff --git a/src/AdvancedLogger.h b/src/AdvancedLogger.h
index 605c629..3823a1d 100644
--- a/src/AdvancedLogger.h
+++ b/src/AdvancedLogger.h
@@ -33,6 +33,8 @@
  * - ADVANCED_LOGGER_TASK_PRIORITY: Priority for the log processing task.
  * - ADVANCED_LOGGER_TASK_CORE: Core ID for the log processing task.
  * - ADVANCED_LOGGER_MAX_MESSAGE_LENGTH: Maximum length of log messages.
+ * - ADVANCED_LOGGER_FLUSH_INTERVAL_MS: Interval in milliseconds for periodic file flushing (default: 5000ms).
+ * - ADVANCED_LOGGER_FLUSH_LOG_LEVEL: Log level that triggers immediate flush (default: ERROR).
  *
  * Usage:
  * In platformio.ini: build_flags = -DADVANCED_LOGGER_ALLOCABLE_HEAP_SIZE=10240
@@ -63,6 +65,14 @@
     #define ADVANCED_LOGGER_MAX_MESSAGE_LENGTH 512
 #endif
 
+#ifndef ADVANCED_LOGGER_FLUSH_INTERVAL_MS
+    #define ADVANCED_LOGGER_FLUSH_INTERVAL_MS 5000  // Flush every 5 seconds
+#endif
+
+#ifndef ADVANCED_LOGGER_FLUSH_LOG_LEVEL
+    #define ADVANCED_LOGGER_FLUSH_LOG_LEVEL LogLevel::ERROR  // Default to ERROR level
+#endif
+
 
 /*
  * Compilation flags to conditionally disable logging: