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 int lttng_ust_log_critical_action = LTTNG_UST_LOG_CRITICAL_ACTION_UNKNOWN;
  14
  15 /*
  16  * Initialize the global log level from the "LTTNG_UST_DEBUG" environment
  17  * variable.
  18  *
  19  * This could end up being called concurrently by multiple threads but doesn't
  20  * require a mutex since the input is invariant across threads and the result
  21  * will be the same.
  22  */
  23 static
  24 void lttng_ust_logging_log_level_init(void)
  25 {
  26         char *lttng_ust_debug;
  27         int current_log_level;
  28
  29         current_log_level = CMM_LOAD_SHARED(lttng_ust_log_level);
  30
  31         /*
  32          * Check early if we are initialized, this is unlikely as it's already tested
  33          * in lttng_ust_logging_debug_enabled before performing lazy initialization.
  34          */
  35         if (caa_unlikely(current_log_level != LTTNG_UST_LOG_LEVEL_UNKNOWN))
  36                 return;
  37
  38         /*
  39          * This getenv is not part of lttng_ust_getenv() because logging is
  40          * used in the getenv initialization and thus logging must be
  41          * initialized prior to getenv.
  42          */
  43         lttng_ust_debug = getenv("LTTNG_UST_DEBUG");
  44
  45         /*
  46          * If the LTTNG_UST_DEBUG environment variable is defined, print all
  47          * messages, otherwise print nothing.
  48          */
  49         if (lttng_ust_debug)
  50                 current_log_level = LTTNG_UST_LOG_LEVEL_DEBUG;
  51         else
  52                 current_log_level = LTTNG_UST_LOG_LEVEL_SILENT;
  53
  54         /* Initialize the log level */
  55         CMM_STORE_SHARED(lttng_ust_log_level, current_log_level);
  56 }
  57
  58 /*
  59  * Initialize the global log critical action from the "LTTNG_UST_ABORT_ON_CRITICAL"
  60  * environment variable.
  61  *
  62  * This could end up being called concurrently by multiple threads but doesn't
  63  * require a mutex since the input is invariant across threads and the result
  64  * will be the same.
  65  */
  66 static
  67 void lttng_ust_logging_log_critical_action_init(void)
  68 {
  69         char *lttng_ust_abort_on_critical;
  70         int current_log_critical_action;
  71
  72         current_log_critical_action = CMM_LOAD_SHARED(lttng_ust_log_critical_action);
  73
  74         /*
  75          * Check early if we are initialized, this is unlikely as it's already tested
  76          * in lttng_ust_logging_abort_on_critical_enabled before performing lazy initialization.
  77          */
  78         if (caa_unlikely(current_log_critical_action != LTTNG_UST_LOG_CRITICAL_ACTION_UNKNOWN))
  79                 return;
  80
  81         /*
  82          * This getenv is not part of lttng_ust_getenv() because logging is
  83          * used in the getenv initialization and thus logging must be
  84          * initialized prior to getenv.
  85          */
  86         lttng_ust_abort_on_critical = getenv("LTTNG_UST_ABORT_ON_CRITICAL");
  87
  88         /*
  89          * If the LTTNG_UST_ABORT_ON_CRITICAL environment variable is defined,
  90          * call abort() on CRIT(), otherwise take no action.
  91          */
  92         if (lttng_ust_abort_on_critical)
  93                 current_log_critical_action = LTTNG_UST_LOG_CRITICAL_ACTION_ABORT;
  94         else
  95                 current_log_critical_action = LTTNG_UST_LOG_CRITICAL_ACTION_NONE;
  96
  97         /* Initialize the log critical action */
  98         CMM_STORE_SHARED(lttng_ust_log_critical_action, current_log_critical_action);
  99 }
 100
 101 /*
 102  * Initialize the global log level from the "LTTNG_UST_DEBUG" environment
 103  * variable and the global log critical action from "LTTNG_UST_ABORT_ON_CRITICAL".
 104  *
 105  * This could end up being called concurrently by multiple threads but doesn't
 106  * require a mutex since the input is invariant across threads and the result
 107  * will be the same.
 108  */
 109 void lttng_ust_logging_init(void)
 110 {
 111         lttng_ust_logging_log_level_init();
 112         lttng_ust_logging_log_critical_action_init();
 113 }