* Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
*/
+#include <urcu/compiler.h>
+#include <urcu/system.h>
+
#include "common/logging.h"
-volatile enum lttng_ust_log_level lttng_ust_log_level;
+int lttng_ust_log_level = LTTNG_UST_LOG_LEVEL_UNKNOWN;
-void lttng_ust_logging_init(void)
+/*
+ * Initialize the global log level from the "LTTNG_UST_DEBUG" environment
+ * variable.
+ *
+ * This could end up being called concurently by multiple threads but doesn't
+ * require a mutex since the input is invariant across threads and the result
+ * will be the same.
+ *
+ * Return the current log level to save the caller a second read of the global
+ * log level.
+ */
+int lttng_ust_logging_init(void)
{
char *lttng_ust_debug;
+ int current_log_level;
+
+ current_log_level = CMM_LOAD_SHARED(lttng_ust_log_level);
+
+ /*
+ * Check early if we are initialized, this is unlikely as it's already tested
+ * in lttng_ust_debug_enabled before performing lazy initialization.
+ */
+ if (caa_unlikely(current_log_level != LTTNG_UST_LOG_LEVEL_UNKNOWN))
+ goto end;
+
+ /*
+ * This getenv is not part of lttng_ust_getenv() because logging is
+ * used in the getenv initialization and thus logging must be
+ * initialized prior to getenv.
+ */
+ lttng_ust_debug = getenv("LTTNG_UST_DEBUG");
+
+ /*
+ * If the LTTNG_UST_DEBUG environment variable is defined, print all
+ * messages, otherwise print nothing.
+ */
+ if (lttng_ust_debug)
+ current_log_level = LTTNG_UST_LOG_LEVEL_DEBUG;
+ else
+ current_log_level = LTTNG_UST_LOG_LEVEL_SILENT;
+
+ /* Initialize the log level */
+ CMM_STORE_SHARED(lttng_ust_log_level, current_log_level);
- if (lttng_ust_log_level == LTTNG_UST_LOG_LEVEL_UNKNOWN) {
- /*
- * This getenv is not part of lttng_ust_getenv() because it
- * is required to print ERR() performed during getenv
- * initialization.
- */
- lttng_ust_debug = getenv("LTTNG_UST_DEBUG");
- if (lttng_ust_debug)
- lttng_ust_log_level = LTTNG_UST_LOG_LEVEL_DEBUG;
- else
- lttng_ust_log_level = LTTNG_UST_LOG_LEVEL_NORMAL;
- }
+end:
+ return current_log_level;
}