src/common/logging.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #include <urcu/compiler.h>
   8 #include <urcu/system.h>
   9
  10 #include "common/logging.h"
  11
  12 int lttng_ust_log_level = LTTNG_UST_LOG_LEVEL_UNKNOWN;
  13
  14 /*
  15  * Initialize the global log level from the "LTTNG_UST_DEBUG" environment
  16  * variable.
  17  *
  18  * This could end up being called concurently by multiple threads but doesn't
  19  * require a mutex since the input is invariant across threads and the result
  20  * will be the same.
  21  *
  22  * Return the current log level to save the caller a second read of the global
  23  * log level.
  24  */
  25 int lttng_ust_logging_init(void)
  26 {
  27         char *lttng_ust_debug;
  28         int current_log_level;
  29
  30         current_log_level = CMM_LOAD_SHARED(lttng_ust_log_level);
  31
  32         /*
  33          * Check early if we are initialized, this is unlikely as it's already tested
  34          * in lttng_ust_debug_enabled before performing lazy initialization.
  35          */
  36         if (caa_unlikely(current_log_level != LTTNG_UST_LOG_LEVEL_UNKNOWN))
  37                 goto end;
  38
  39         /*
  40          * This getenv is not part of lttng_ust_getenv() because logging is
  41          * used in the getenv initialization and thus logging must be
  42          * initialized prior to getenv.
  43          */
  44         lttng_ust_debug = getenv("LTTNG_UST_DEBUG");
  45
  46         /*
  47          * If the LTTNG_UST_DEBUG environment variable is defined, print all
  48          * messages, otherwise print nothing.
  49          */
  50         if (lttng_ust_debug)
  51                 current_log_level = LTTNG_UST_LOG_LEVEL_DEBUG;
  52         else
  53                 current_log_level = LTTNG_UST_LOG_LEVEL_SILENT;
  54
  55         /* Initialize the log level */
  56         CMM_STORE_SHARED(lttng_ust_log_level, current_log_level);
  57
  58 end:
  59         return current_log_level;
  60 }