1MONGOC_LOGGING(3)                  libmongoc                 MONGOC_LOGGING(3)
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NAME

6       mongoc_logging - Logging
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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);
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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.
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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"
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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:
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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_init ();
89             mongoc_log_set_handler (my_logger, NULL);
90
91             /* ... your code ...  */
92
93             mongoc_cleanup ();
94             return 0;
95          }
96
97       To restore the default handler:
98
99          mongoc_log_set_handler (mongoc_log_default_handler, NULL);
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DISABLE LOGGING

102       To disable all  logging,  including  warnings,  critical  messages  and
103       errors, provide an empty log handler:
104
105          mongoc_log_set_handler (NULL, NULL);
106

TRACING

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

125       MongoDB, Inc
126

128       2017-present, MongoDB, Inc
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1331.16.2                           Feb 25, 2020                MONGOC_LOGGING(3)
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