lib/vlog.h

   1 /*
   2  * Copyright (c) 2008, 2009, 2010, 2011 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 "compiler.h"
  25 #include "util.h"
  26
  27 #ifdef  __cplusplus
  28 extern "C" {
  29 #endif
  30
  31 /* Logging importance levels.
  32  *
  33  * The following log levels, in descending order of importance, are enabled by
  34  * default:
  35  *
  36  *   - EMER: Not currently used.
  37  *
  38  *   - ERR: A high-level operation or a subsystem failed.  Attention is
  39  *     warranted.
  40  *
  41  *   - WARN: A low-level operation failed, but higher-level subsystems may be
  42  *     able to recover.
  43  *
  44  *   - INFO: Information that may be useful in retrospect when investigating
  45  *     a problem.
  46  *
  47  * The lowest log level is not enabled by default:
  48  *
  49  *   - DBG: Information useful only to someone with intricate knowledge of the
  50  *     system, or that would commonly cause too-voluminous log output.
  51  */
  52 #define VLOG_LEVELS                             \
  53     VLOG_LEVEL(EMER, LOG_ALERT)                 \
  54     VLOG_LEVEL(ERR, LOG_ERR)                    \
  55     VLOG_LEVEL(WARN, LOG_WARNING)               \
  56     VLOG_LEVEL(INFO, LOG_NOTICE)                \
  57     VLOG_LEVEL(DBG, LOG_DEBUG)
  58 enum vlog_level {
  59 #define VLOG_LEVEL(NAME, SYSLOG_LEVEL) VLL_##NAME,
  60     VLOG_LEVELS
  61 #undef VLOG_LEVEL
  62     VLL_N_LEVELS
  63 };
  64
  65 const char *vlog_get_level_name(enum vlog_level);
  66 enum vlog_level vlog_get_level_val(const char *name);
  67
  68 /* Facilities that we can log to. */
  69 #define VLOG_FACILITIES                                         \
  70     VLOG_FACILITY(SYSLOG, "%05N|%c|%p|%m")                      \
  71     VLOG_FACILITY(CONSOLE, "%d{%b %d %H:%M:%S}|%05N|%c|%p|%m")  \
  72     VLOG_FACILITY(FILE, "%d{%b %d %H:%M:%S}|%05N|%c|%p|%m")
  73 enum vlog_facility {
  74 #define VLOG_FACILITY(NAME, PATTERN) VLF_##NAME,
  75     VLOG_FACILITIES
  76 #undef VLOG_FACILITY
  77     VLF_N_FACILITIES,
  78     VLF_ANY_FACILITY = -1
  79 };
  80
  81 const char *vlog_get_facility_name(enum vlog_facility);
  82 enum vlog_facility vlog_get_facility_val(const char *name);
  83
  84 /* A log module. */
  85 struct vlog_module {
  86     const char *name;             /* User-visible name. */
  87     int levels[VLF_N_FACILITIES]; /* Minimum log level for each facility. */
  88     int min_level;                /* Minimum log level for any facility. */
  89 };
  90
  91 /* Creates and initializes a global instance of a module named MODULE. */
  92 #if USE_LINKER_SECTIONS
  93 #define VLOG_DEFINE_MODULE(MODULE)                                      \
  94         VLOG_DEFINE_MODULE__(MODULE)                                    \
  95         extern struct vlog_module *vlog_module_ptr_##MODULE;            \
  96         struct vlog_module *vlog_module_ptr_##MODULE                    \
  97             __attribute__((section("vlog_modules"))) = &VLM_##MODULE
  98 #else
  99 #define VLOG_DEFINE_MODULE(MODULE) extern struct vlog_module VLM_##MODULE
 100 #endif
 101
 102 const char *vlog_get_module_name(const struct vlog_module *);
 103 struct vlog_module *vlog_module_from_name(const char *name);
 104
 105 /* Rate-limiter for log messages. */
 106 struct vlog_rate_limit {
 107     /* Configuration settings. */
 108     unsigned int rate;          /* Tokens per second. */
 109     unsigned int burst;         /* Max cumulative tokens credit. */
 110
 111     /* Current status. */
 112     unsigned int tokens;        /* Current number of tokens. */
 113     time_t last_fill;           /* Last time tokens added. */
 114     time_t first_dropped;       /* Time first message was dropped. */
 115     time_t last_dropped;        /* Time of most recent message drop. */
 116     unsigned int n_dropped;     /* Number of messages dropped. */
 117 };
 118
 119 /* Number of tokens to emit a message.  We add 'rate' tokens per second, which
 120  * is 60 times the unit used for 'rate', thus 60 tokens are required to emit
 121  * one message. */
 122 #define VLOG_MSG_TOKENS 60
 123
 124 /* Initializer for a struct vlog_rate_limit, to set up a maximum rate of RATE
 125  * messages per minute and a maximum burst size of BURST messages. */
 126 #define VLOG_RATE_LIMIT_INIT(RATE, BURST)                   \
 127         {                                                   \
 128             RATE,                           /* rate */      \
 129             (MIN(BURST, UINT_MAX / VLOG_MSG_TOKENS)         \
 130              * VLOG_MSG_TOKENS),            /* burst */     \
 131             0,                              /* tokens */    \
 132             0,                              /* last_fill */ \
 133             0,                              /* first_dropped */ \
 134             0,                              /* last_dropped */ \
 135             0,                              /* n_dropped */ \
 136         }
 137
 138 /* Configuring how each module logs messages. */
 139 enum vlog_level vlog_get_level(const struct vlog_module *, enum vlog_facility);
 140 void vlog_set_levels(struct vlog_module *,
 141                      enum vlog_facility, enum vlog_level);
 142 char *vlog_set_levels_from_string(const char *);
 143 char *vlog_get_levels(void);
 144 bool vlog_is_enabled(const struct vlog_module *, enum vlog_level);
 145 bool vlog_should_drop(const struct vlog_module *, enum vlog_level,
 146                       struct vlog_rate_limit *);
 147 void vlog_set_verbosity(const char *arg);
 148
 149 /* Configuring log facilities. */
 150 void vlog_set_pattern(enum vlog_facility, const char *pattern);
 151 const char *vlog_get_log_file(void);
 152 int vlog_set_log_file(const char *file_name);
 153 int vlog_reopen_log_file(void);
 154
 155 /* Initialization. */
 156 void vlog_init(void);
 157 void vlog_exit(void);
 158
 159 /* Functions for actual logging. */
 160 void vlog(const struct vlog_module *, enum vlog_level, const char *format, ...)
 161     PRINTF_FORMAT (3, 4);
 162 void vlog_valist(const struct vlog_module *, enum vlog_level,
 163                  const char *, va_list)
 164     PRINTF_FORMAT (3, 0);
 165
 166 void vlog_fatal(const struct vlog_module *, enum vlog_level,
 167                 const char *format, ...)
 168     PRINTF_FORMAT (3, 4) NO_RETURN;
 169 void vlog_fatal_valist(const struct vlog_module *, enum vlog_level,
 170                        const char *, va_list)
 171     PRINTF_FORMAT (3, 0) NO_RETURN;
 172
 173 void vlog_rate_limit(const struct vlog_module *, enum vlog_level,
 174                      struct vlog_rate_limit *, const char *, ...)
 175     PRINTF_FORMAT (4, 5);
 176
 177 /* Creates and initializes a global instance of a module named MODULE, and
 178  * defines a static variable named THIS_MODULE that points to it, for use with
 179  * the convenience macros below. */
 180 #define VLOG_DEFINE_THIS_MODULE(MODULE)                                 \
 181         VLOG_DEFINE_MODULE(MODULE);                                     \
 182         static struct vlog_module *const THIS_MODULE = &VLM_##MODULE
 183
 184 /* Convenience macros.  These assume that THIS_MODULE points to a "struct
 185  * vlog_module" for the current module, as set up by e.g. the
 186  * VLOG_DEFINE_MODULE macro above.
 187  *
 188  * Guaranteed to preserve errno.
 189  */
 190 #define VLOG_FATAL(...) vlog_fatal(THIS_MODULE, VLL_ERR, __VA_ARGS__)
 191 #define VLOG_EMER(...) VLOG(VLL_EMER, __VA_ARGS__)
 192 #define VLOG_ERR(...) VLOG(VLL_ERR, __VA_ARGS__)
 193 #define VLOG_WARN(...) VLOG(VLL_WARN, __VA_ARGS__)
 194 #define VLOG_INFO(...) VLOG(VLL_INFO, __VA_ARGS__)
 195 #define VLOG_DBG(...) VLOG(VLL_DBG, __VA_ARGS__)
 196
 197 /* More convenience macros, for testing whether a given level is enabled in
 198  * THIS_MODULE.  When constructing a log message is expensive, this enables it
 199  * to be skipped. */
 200 #define VLOG_IS_EMER_ENABLED() true
 201 #define VLOG_IS_ERR_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_ERR)
 202 #define VLOG_IS_WARN_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_WARN)
 203 #define VLOG_IS_INFO_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_INFO)
 204 #define VLOG_IS_DBG_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_DBG)
 205
 206 /* Convenience macros for rate-limiting.
 207  * Guaranteed to preserve errno.
 208  */
 209 #define VLOG_ERR_RL(RL, ...) VLOG_RL(RL, VLL_ERR, __VA_ARGS__)
 210 #define VLOG_WARN_RL(RL, ...) VLOG_RL(RL, VLL_WARN, __VA_ARGS__)
 211 #define VLOG_INFO_RL(RL, ...) VLOG_RL(RL, VLL_INFO, __VA_ARGS__)
 212 #define VLOG_DBG_RL(RL, ...) VLOG_RL(RL, VLL_DBG, __VA_ARGS__)
 213
 214 #define VLOG_DROP_ERR(RL) vlog_should_drop(THIS_MODULE, VLL_ERR, RL)
 215 #define VLOG_DROP_WARN(RL) vlog_should_drop(THIS_MODULE, VLL_WARN, RL)
 216 #define VLOG_DROP_INFO(RL) vlog_should_drop(THIS_MODULE, VLL_INFO, RL)
 217 #define VLOG_DROP_DBG(RL) vlog_should_drop(THIS_MODULE, VLL_DBG, RL)
 218
 219 /* Macros for logging at most once per execution. */
 220 #define VLOG_ERR_ONCE(...) VLOG_ONCE(VLL_ERR, __VA_ARGS__)
 221 #define VLOG_WARN_ONCE(...) VLOG_ONCE(VLL_WARN, __VA_ARGS__)
 222 #define VLOG_INFO_ONCE(...) VLOG_ONCE(VLL_INFO, __VA_ARGS__)
 223 #define VLOG_DBG_ONCE(...) VLOG_ONCE(VLL_DBG, __VA_ARGS__)
 224
 225 /* Command line processing. */
 226 #define VLOG_OPTION_ENUMS OPT_LOG_FILE
 227 #define VLOG_LONG_OPTIONS                                   \
 228         {"verbose",     optional_argument, NULL, 'v'},         \
 229         {"log-file",    optional_argument, NULL, OPT_LOG_FILE}
 230 #define VLOG_OPTION_HANDLERS                    \
 231         case 'v':                               \
 232             vlog_set_verbosity(optarg);         \
 233             break;                              \
 234         case OPT_LOG_FILE:                      \
 235             vlog_set_log_file(optarg);          \
 236             break;
 237 void vlog_usage(void);
 238
 239 /* Implementation details. */
 240 #define VLOG(LEVEL, ...)                                \
 241     do {                                                \
 242         enum vlog_level level__ = LEVEL;                \
 243         if (THIS_MODULE->min_level >= level__) {        \
 244             vlog(THIS_MODULE, level__, __VA_ARGS__);    \
 245         }                                               \
 246     } while (0)
 247 #define VLOG_RL(RL, LEVEL, ...)                                     \
 248     do {                                                            \
 249         enum vlog_level level__ = LEVEL;                            \
 250         if (THIS_MODULE->min_level >= level__) {                    \
 251             vlog_rate_limit(THIS_MODULE, level__, RL, __VA_ARGS__); \
 252         }                                                           \
 253     } while (0)
 254 #define VLOG_ONCE(LEVEL, ...)                       \
 255     do {                                            \
 256         static bool already_logged;                 \
 257         if (!already_logged) {                      \
 258             already_logged = true;                  \
 259             vlog(THIS_MODULE, LEVEL, __VA_ARGS__);  \
 260         }                                           \
 261     } while (0)
 262
 263 #define VLOG_DEFINE_MODULE__(MODULE)                                    \
 264         extern struct vlog_module VLM_##MODULE;                         \
 265         struct vlog_module VLM_##MODULE =                               \
 266         {                                                               \
 267             #MODULE,                                      /* name */    \
 268             { [ 0 ... VLF_N_FACILITIES - 1] = VLL_INFO }, /* levels */  \
 269             VLL_INFO,                                     /* min_level */ \
 270         };
 271
 272 #ifdef  __cplusplus
 273 }
 274 #endif
 275
 276
 277 #endif /* vlog.h */