1MONGOC_LOGGING(3)                  libmongoc                 MONGOC_LOGGING(3)
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NAME

6       mongoc_logging - Logging
7
8       MongoDB C driver Logging Abstraction
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SYNOPSIS

11          typedef enum {
12             MONGOC_LOG_LEVEL_ERROR,
13             MONGOC_LOG_LEVEL_CRITICAL,
14             MONGOC_LOG_LEVEL_WARNING,
15             MONGOC_LOG_LEVEL_MESSAGE,
16             MONGOC_LOG_LEVEL_INFO,
17             MONGOC_LOG_LEVEL_DEBUG,
18             MONGOC_LOG_LEVEL_TRACE,
19          } mongoc_log_level_t;
20
21          #define MONGOC_ERROR(...)
22          #define MONGOC_CRITICAL(...)
23          #define MONGOC_WARNING(...)
24          #define MONGOC_MESSAGE(...)
25          #define MONGOC_INFO(...)
26          #define MONGOC_DEBUG(...)
27
28          typedef void (*mongoc_log_func_t) (mongoc_log_level_t log_level,
29                                             const char *log_domain,
30                                             const char *message,
31                                             void *user_data);
32
33          void
34          mongoc_log_set_handler (mongoc_log_func_t log_func, void *user_data);
35          void
36          mongoc_log (mongoc_log_level_t log_level,
37                      const char *log_domain,
38                      const char *format,
39                      ...) BSON_GNUC_PRINTF (3, 4);
40          const char *
41          mongoc_log_level_str (mongoc_log_level_t log_level);
42          void
43          mongoc_log_default_handler (mongoc_log_level_t log_level,
44                                      const char *log_domain,
45                                      const char *message,
46                                      void *user_data);
47          void
48          mongoc_log_trace_enable (void);
49          void
50          mongoc_log_trace_disable (void);
51
52       The MongoDB C driver comes with an abstraction for logging that you can
53       use in your application, or integrate with an existing logging system.
54

MACROS

56       To make logging a little less painful, various helper macros  are  pro‐
57       vided. See the following example.
58
59          #undef MONGOC_LOG_DOMAIN
60          #define MONGOC_LOG_DOMAIN "my-custom-domain"
61
62          MONGOC_WARNING ("An error occurred: %s", strerror (errno));
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CUSTOM LOG HANDLERS

65       The  default log handler prints a timestamp and the log message to std‐
66       out, or to stderr for warnings, critical messages, and errors.
67              You can  override  the  handler  with  mongoc_log_set_handler().
68              Your handler function is called in a mutex for thread safety.
69
70       For  example,  you could register a custom handler to suppress messages
71       at INFO level and below:
72
73          void
74          my_logger (mongoc_log_level_t log_level,
75                     const char *log_domain,
76                     const char *message,
77                     void *user_data)
78          {
79             /* smaller values are more important */
80             if (log_level < MONGOC_LOG_LEVEL_INFO) {
81                mongoc_log_default_handler (log_level, log_domain, message, user_data);
82             }
83          }
84
85          int
86          main (int argc, char *argv[])
87          {
88             mongoc_log_set_handler (my_logger, NULL);
89             mongoc_init ();
90
91             /* ... your code ...  */
92
93             mongoc_cleanup ();
94             return 0;
95          }
96
97       Note that in the example above mongoc_log_set_handler() is  called  be‐
98       fore  mongoc_init().  Otherwise, some log traces could not be processed
99       by the log handler.
100
101       To restore the default handler:
102
103          mongoc_log_set_handler (mongoc_log_default_handler, NULL);
104

DISABLE LOGGING

106       To disable all logging, including warnings, critical messages  and  er‐
107       rors, provide an empty log handler:
108
109          mongoc_log_set_handler (NULL, NULL);
110

TRACING

112       If  compiling your own copy of the MongoDB C driver, consider configur‐
113       ing with -DENABLE_TRACING=ON to enable function tracing and  hex  dumps
114       of  network  packets to STDERR and STDOUT during development and debug‐
115       ging.
116
117       This is especially useful when debugging what may be  going  on  inter‐
118       nally in the driver.
119
120       Trace   messages   can   be   enabled  and  disabled  by  calling  mon‐
121       goc_log_trace_enable() and mongoc_log_trace_disable()
122
123       NOTE:
124          Compiling the driver with -DENABLE_TRACING=ON will affect  its  per‐
125          formance. Disabling tracing with mongoc_log_trace_disable() signifi‐
126          cantly reduces the overhead, but cannot remove it completely.
127

AUTHOR

129       MongoDB, Inc
130

132       2017-present, MongoDB, Inc
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1371.21.1                           Mar 02, 2022                MONGOC_LOGGING(3)
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