X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=src%2Fcommon%2Flogging.c;h=fb3f119fcbba3c34e32e6741c6686c17f33ed6a3;hb=662d05907560345f06a19463ce5bf24ca72a442c;hp=eb610833676d46519cd7e7437e36d00df3f84654;hpb=c6e6343c93e1b6ec02de1f9dc825faae0d6cc7ab;p=lttng-ust.git

diff --git a/src/common/logging.c b/src/common/logging.c
index eb610833..fb3f119f 100644
--- a/src/common/logging.c
+++ b/src/common/logging.c
@@ -4,24 +4,57 @@
  * 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;
 }