lib/vlog.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef VLOG_H
  18 #define VLOG_H 1
  19
  20 #include <limits.h>
  21 #include <stdarg.h>
  22 #include <stdbool.h>
  23 #include <time.h>
  24 #include "util.h"
  25
  26 #ifdef  __cplusplus
  27 extern "C" {
  28 #endif
  29
  30 /* Logging importance levels. */
  31 #define VLOG_LEVELS                             \
  32     VLOG_LEVEL(EMER, LOG_ALERT)                 \
  33     VLOG_LEVEL(ERR, LOG_ERR)                    \
  34     VLOG_LEVEL(WARN, LOG_WARNING)               \
  35     VLOG_LEVEL(INFO, LOG_NOTICE)                \
  36     VLOG_LEVEL(DBG, LOG_DEBUG)
  37 enum vlog_level {
  38 #define VLOG_LEVEL(NAME, SYSLOG_LEVEL) VLL_##NAME,
  39     VLOG_LEVELS
  40 #undef VLOG_LEVEL
  41     VLL_N_LEVELS
  42 };
  43
  44 const char *vlog_get_level_name(enum vlog_level);
  45 enum vlog_level vlog_get_level_val(const char *name);
  46
  47 /* Facilities that we can log to. */
  48 #define VLOG_FACILITIES                                         \
  49     VLOG_FACILITY(SYSLOG, "%05N|%c|%p|%m")                      \
  50     VLOG_FACILITY(CONSOLE, "%d{%b %d %H:%M:%S}|%05N|%c|%p|%m")  \
  51     VLOG_FACILITY(FILE, "%d{%b %d %H:%M:%S}|%05N|%c|%p|%m")
  52 enum vlog_facility {
  53 #define VLOG_FACILITY(NAME, PATTERN) VLF_##NAME,
  54     VLOG_FACILITIES
  55 #undef VLOG_FACILITY
  56     VLF_N_FACILITIES,
  57     VLF_ANY_FACILITY = -1
  58 };
  59
  60 const char *vlog_get_facility_name(enum vlog_facility);
  61 enum vlog_facility vlog_get_facility_val(const char *name);
  62
  63 /* A log module. */
  64 struct vlog_module {
  65     const char *name;             /* User-visible name. */
  66     int levels[VLF_N_FACILITIES]; /* Minimum log level for each facility. */
  67     int min_level;                /* Minimum log level for any facility. */
  68 };
  69
  70 /* Creates and initializes a global instance of a module named MODULE. */
  71 #if USE_LINKER_SECTIONS
  72 #define VLOG_DEFINE_MODULE(MODULE)                                      \
  73         VLOG_DEFINE_MODULE__(MODULE)                                    \
  74         struct vlog_module *vlog_module_ptr_##MODULE                    \
  75             __attribute__((section("vlog_modules"))) = &VLM_##MODULE;
  76 #else
  77 #define VLOG_DEFINE_MODULE(MODULE) extern struct vlog_module VLM_##MODULE;
  78 #endif
  79
  80 const char *vlog_get_module_name(const struct vlog_module *);
  81 struct vlog_module *vlog_module_from_name(const char *name);
  82
  83 /* Rate-limiter for log messages. */
  84 struct vlog_rate_limit {
  85     /* Configuration settings. */
  86     unsigned int rate;          /* Tokens per second. */
  87     unsigned int burst;         /* Max cumulative tokens credit. */
  88
  89     /* Current status. */
  90     unsigned int tokens;        /* Current number of tokens. */
  91     time_t last_fill;           /* Last time tokens added. */
  92     time_t first_dropped;       /* Time first message was dropped. */
  93     unsigned int n_dropped;     /* Number of messages dropped. */
  94 };
  95
  96 /* Number of tokens to emit a message.  We add 'rate' tokens per second, which
  97  * is 60 times the unit used for 'rate', thus 60 tokens are required to emit
  98  * one message. */
  99 #define VLOG_MSG_TOKENS 60
 100
 101 /* Initializer for a struct vlog_rate_limit, to set up a maximum rate of RATE
 102  * messages per minute and a maximum burst size of BURST messages. */
 103 #define VLOG_RATE_LIMIT_INIT(RATE, BURST)                   \
 104         {                                                   \
 105             RATE,                           /* rate */      \
 106             (MIN(BURST, UINT_MAX / VLOG_MSG_TOKENS)         \
 107              * VLOG_MSG_TOKENS),            /* burst */     \
 108             0,                              /* tokens */    \
 109             0,                              /* last_fill */ \
 110             0,                              /* first_dropped */ \
 111             0,                              /* n_dropped */ \
 112         }
 113
 114 /* Configuring how each module logs messages. */
 115 enum vlog_level vlog_get_level(const struct vlog_module *, enum vlog_facility);
 116 void vlog_set_levels(struct vlog_module *,
 117                      enum vlog_facility, enum vlog_level);
 118 char *vlog_set_levels_from_string(const char *);
 119 char *vlog_get_levels(void);
 120 bool vlog_is_enabled(const struct vlog_module *, enum vlog_level);
 121 bool vlog_should_drop(const struct vlog_module *, enum vlog_level,
 122                       struct vlog_rate_limit *);
 123 void vlog_set_verbosity(const char *arg);
 124
 125 /* Configuring log facilities. */
 126 void vlog_set_pattern(enum vlog_facility, const char *pattern);
 127 const char *vlog_get_log_file(void);
 128 int vlog_set_log_file(const char *file_name);
 129 int vlog_reopen_log_file(void);
 130
 131 /* Function for actual logging. */
 132 void vlog_init(void);
 133 void vlog_exit(void);
 134 void vlog(const struct vlog_module *, enum vlog_level, const char *format, ...)
 135     __attribute__((format(printf, 3, 4)));
 136 void vlog_valist(const struct vlog_module *, enum vlog_level,
 137                  const char *, va_list)
 138     __attribute__((format(printf, 3, 0)));
 139 void vlog_rate_limit(const struct vlog_module *, enum vlog_level,
 140                      struct vlog_rate_limit *, const char *, ...)
 141     __attribute__((format(printf, 4, 5)));
 142
 143 /* Creates and initializes a global instance of a module named MODULE, and
 144  * defines a static variable named THIS_MODULE that points to it, for use with
 145  * the convenience macros below. */
 146 #define VLOG_DEFINE_THIS_MODULE(MODULE)                                 \
 147         VLOG_DEFINE_MODULE(MODULE)                                      \
 148         static struct vlog_module *const THIS_MODULE = &VLM_##MODULE;
 149
 150 /* Convenience macros.  These assume that THIS_MODULE points to a "struct
 151  * vlog_module" for the current module, as set up by e.g. the
 152  * VLOG_DEFINE_MODULE macro above.
 153  *
 154  * Guaranteed to preserve errno.
 155  */
 156 #define VLOG_EMER(...) VLOG(VLL_EMER, __VA_ARGS__)
 157 #define VLOG_ERR(...) VLOG(VLL_ERR, __VA_ARGS__)
 158 #define VLOG_WARN(...) VLOG(VLL_WARN, __VA_ARGS__)
 159 #define VLOG_INFO(...) VLOG(VLL_INFO, __VA_ARGS__)
 160 #define VLOG_DBG(...) VLOG(VLL_DBG, __VA_ARGS__)
 161
 162 /* More convenience macros, for testing whether a given level is enabled in
 163  * THIS_MODULE.  When constructing a log message is expensive, this enables it
 164  * to be skipped. */
 165 #define VLOG_IS_EMER_ENABLED() true
 166 #define VLOG_IS_ERR_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_EMER)
 167 #define VLOG_IS_WARN_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_WARN)
 168 #define VLOG_IS_INFO_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_INFO)
 169 #define VLOG_IS_DBG_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_DBG)
 170
 171 /* Convenience macros for rate-limiting.
 172  * Guaranteed to preserve errno.
 173  */
 174 #define VLOG_ERR_RL(RL, ...) VLOG_RL(RL, VLL_ERR, __VA_ARGS__)
 175 #define VLOG_WARN_RL(RL, ...) VLOG_RL(RL, VLL_WARN, __VA_ARGS__)
 176 #define VLOG_INFO_RL(RL, ...) VLOG_RL(RL, VLL_INFO, __VA_ARGS__)
 177 #define VLOG_DBG_RL(RL, ...) VLOG_RL(RL, VLL_DBG, __VA_ARGS__)
 178
 179 #define VLOG_DROP_ERR(RL) vlog_should_drop(THIS_MODULE, VLL_ERR, RL)
 180 #define VLOG_DROP_WARN(RL) vlog_should_drop(THIS_MODULE, VLL_WARN, RL)
 181 #define VLOG_DROP_INFO(RL) vlog_should_drop(THIS_MODULE, VLL_INFO, RL)
 182 #define VLOG_DROP_DBG(RL) vlog_should_drop(THIS_MODULE, VLL_DBG, RL)
 183
 184 /* Command line processing. */
 185 #define VLOG_OPTION_ENUMS OPT_LOG_FILE
 186 #define VLOG_LONG_OPTIONS                                   \
 187         {"verbose",     optional_argument, 0, 'v'},         \
 188         {"log-file",    optional_argument, 0, OPT_LOG_FILE}
 189 #define VLOG_OPTION_HANDLERS                    \
 190         case 'v':                               \
 191             vlog_set_verbosity(optarg);         \
 192             break;                              \
 193         case OPT_LOG_FILE:                      \
 194             vlog_set_log_file(optarg);          \
 195             break;
 196 void vlog_usage(void);
 197
 198 /* Implementation details. */
 199 #define VLOG(LEVEL, ...)                            \
 200     do {                                            \
 201         if (THIS_MODULE->min_level >= LEVEL) {      \
 202             vlog(THIS_MODULE, LEVEL, __VA_ARGS__);  \
 203         }                                           \
 204     } while (0)
 205 #define VLOG_RL(RL, LEVEL, ...)                                     \
 206     do {                                                            \
 207         if (THIS_MODULE->min_level >= LEVEL) {                      \
 208             vlog_rate_limit(THIS_MODULE, LEVEL, RL, __VA_ARGS__);   \
 209         }                                                           \
 210     } while (0)
 211 #define VLOG_DEFINE_MODULE__(MODULE)                                    \
 212         struct vlog_module VLM_##MODULE =                               \
 213         {                                                               \
 214             #MODULE,                                      /* name */    \
 215             { [ 0 ... VLF_N_FACILITIES - 1] = VLL_INFO }, /* levels */  \
 216             VLL_INFO,                                     /* min_level */ \
 217         };
 218
 219 #ifdef  __cplusplus
 220 }
 221 #endif
 222
 223
 224 #endif /* vlog.h */