added logging_helper for futuer C++ backends

src/damaris/backend/logging_helper.h

@@ -0,0 +1,134 @@
+// -*- C++ -*-
+/**
+ * @file logging_helper.h
+ * @brief Lightweight logging helper for the DAMARIS C++ backend.
+ *
+ * Writes structured log messages to stdout in a format parseable by the
+ * Python FileTailerHandler:
+ *
+ *   [LEVEL] message
+ *
+ * Levels: DEBUG, INFO, WARNING, ERROR, CRITICAL
+ *
+ * Usage in C++ code:
+ *   #include "logging_helper.h"
+ *   log_info("Starting backend, spool=%s", spool_dir.c_str());
+ *   log_error("Failed to open device: %s", strerror(errno));
+ */
+
+#ifndef DAMARIS_LOGGING_HELPER_H
+#define DAMARIS_LOGGING_HELPER_H
+
+#include <cstdio>
+#include <cstdarg>
+#include <cstring>
+#include <ctime>
+#include <string>
+
+namespace damaris {
+namespace logging {
+
+// ---------------------------------------------------------------------------
+// Internal helpers
+// ---------------------------------------------------------------------------
+
+inline std::string timestamp() {
+    char buf[32];
+    time_t now = time(nullptr);
+    struct tm tm_buf;
+#ifdef _WIN32
+    localtime_s(&tm_buf, &now);
+#else
+    localtime_r(&now, &tm_buf);
+#endif
+    strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", &tm_buf);
+    return std::string(buf);
+}
+
+inline void log_message(int level, const char* fmt, ...) {
+    const char* level_str = "INFO";
+    switch (level) {
+        case 0: level_str = "DEBUG"; break;
+        case 1: level_str = "INFO";  break;
+        case 2: level_str = "WARNING"; break;
+        case 3: level_str = "ERROR";   break;
+        case 4: level_str = "CRITICAL"; break;
+    }
+
+    char msg[4096];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, args);
+    va_end(args);
+
+    fprintf(stdout, "[%s] %s\n", level_str, msg);
+    fflush(stdout);
+}
+
+// ---------------------------------------------------------------------------
+// Convenience macros / inline functions
+// ---------------------------------------------------------------------------
+
+inline void log_debug(const char* fmt, ...) {
+    char msg[4096];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, args);
+    va_end(args);
+    fprintf(stdout, "[DEBUG] %s\n", msg);
+    fflush(stdout);
+}
+
+inline void log_info(const char* fmt, ...) {
+    char msg[4096];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, args);
+    va_end(args);
+    fprintf(stdout, "[INFO] %s\n", msg);
+    fflush(stdout);
+}
+
+inline void log_warning(const char* fmt, ...) {
+    char msg[4096];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, args);
+    va_end(args);
+    fprintf(stdout, "[WARNING] %s\n", msg);
+    fflush(stdout);
+}
+
+inline void log_error(const char* fmt, ...) {
+    char msg[4096];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, args);
+    va_end(args);
+    fprintf(stdout, "[ERROR] %s\n", msg);
+    fflush(stdout);
+}
+
+inline void log_critical(const char* fmt, ...) {
+    char msg[4096];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(msg, sizeof(msg), fmt, args);
+    va_end(args);
+    fprintf(stdout, "[CRITICAL] %s\n", msg);
+    fflush(stdout);
+}
+
+} // namespace logging
+} // namespace damaris
+
+// ---------------------------------------------------------------------------
+// Optional C-style macros for convenience
+// ---------------------------------------------------------------------------
+#define DAMARIS_LOG_DEBUG(fmt, ...)   damaris::logging::log_debug(fmt, ##__VA_ARGS__)
+#define DAMARIS_LOG_INFO(fmt, ...)    damaris::logging::log_info(fmt, ##__VA_ARGS__)
+#define DAMARIS_LOG_WARNING(fmt, ...) damaris::logging::log_warning(fmt, ##__VA_ARGS__)
+#define DAMARIS_LOG_ERROR(fmt, ...)   damaris::logging::log_error(fmt, ##__VA_ARGS__)
+#define DAMARIS_LOG_CRITICAL(fmt, ...) damaris::logging::log_critical(fmt, ##__VA_ARGS__)
+
+#endif // DAMARIS_LOGGING_HELPER_H