1 // Copyright 1999, 2007 Google Inc. All Rights Reserved.
2 // Author: Ray Sidney and many others
4 // Defines the VLOG_IS_ON macro that controls the variable-verbosity
5 // conditional logging.
7 // It's used by VLOG and VLOG_IF in logging.h
8 // and by RAW_VLOG in raw_logging.h to trigger the logging.
10 // It can also be used directly e.g. like this:
11 // if (VLOG_IS_ON(2)) {
12 // // do some logging preparation and logging
13 // // that can't be accomplished e.g. via just VLOG(2) << ...;
16 // The truth value that VLOG_IS_ON(level) returns is determined by
17 // the three verbosity level flags:
18 // --v=<n> Gives the default maximal active V-logging level;
20 // Normally positive values are used for V-logging levels.
21 // --vmodule=<str> Gives the per-module maximal V-logging levels to override
22 // the value given by --v.
23 // E.g. "my_module=2,foo*=3" would change the logging level
24 // for all code in source files "my_module.*" and "foo*.*"
25 // ("-inl" suffixes are also disregarded for this matching).
27 // SetVLOGLevel helper function is provided to do limited dynamic control over
28 // V-logging by overriding the per-module settings given via --vmodule flag.
30 // CAVEAT: --vmodule functionality is not available in non gcc compilers.
33 #ifndef BASE_VLOG_IS_ON_H_
34 #define BASE_VLOG_IS_ON_H_
36 #include "glog/log_severity.h"
39 // We emit an anonymous static int* variable at every VLOG_IS_ON(n) site.
40 // (Normally) the first time every VLOG_IS_ON(n) site is hit,
41 // we determine what variable will dynamically control logging at this site:
42 // it's either FLAGS_v or an appropriate internal variable
43 // matching the current source file that represents results of
44 // parsing of --vmodule flag and/or SetVLOGLevel calls.
45 #define VLOG_IS_ON(verboselevel) \
46 ({ static @ac_google_namespace@::int32* vlocal__ = &@ac_google_namespace@::kLogSiteUninitialized; \
47 @ac_google_namespace@::int32 verbose_level__ = (verboselevel); \
48 (*vlocal__ >= verbose_level__) && \
49 ((vlocal__ != &@ac_google_namespace@::kLogSiteUninitialized) || \
50 (@ac_google_namespace@::InitVLOG3__(&vlocal__, &FLAGS_v, \
51 __FILE__, verbose_level__))); })
53 // GNU extensions not available, so we do not support --vmodule.
54 // Dynamic value of FLAGS_v always controls the logging level.
55 #define VLOG_IS_ON(verboselevel) (FLAGS_v >= (verboselevel))
58 // Set VLOG(_IS_ON) level for module_pattern to log_level.
59 // This lets us dynamically control what is normally set by the --vmodule flag.
60 // Returns the level that previously applied to module_pattern.
61 // NOTE: To change the log level for VLOG(_IS_ON) sites
62 // that have already executed after/during InitGoogleLogging,
63 // one needs to supply the exact --vmodule pattern that applied to them.
64 // (If no --vmodule pattern applied to them
65 // the value of FLAGS_v will continue to control them.)
66 extern int SetVLOGLevel(const char* module_pattern, int log_level);
68 // Various declarations needed for VLOG_IS_ON above: =========================
70 // Special value used to indicate that a VLOG_IS_ON site has not been
71 // initialized. We make this a large value, so the common-case check
72 // of "*vlocal__ >= verbose_level__" in VLOG_IS_ON definition
73 // passes in such cases and InitVLOG3__ is then triggered.
74 extern @ac_google_namespace@::int32 kLogSiteUninitialized;
76 // Helper routine which determines the logging info for a particalur VLOG site.
77 // site_flag is the address of the site-local pointer to the controlling
79 // site_default is the default to use for *site_flag
80 // fname is the current source file name
81 // verbose_level is the argument to VLOG_IS_ON
82 // We will return the return value for VLOG_IS_ON
83 // and if possible set *site_flag appropriately.
84 extern bool InitVLOG3__(@ac_google_namespace@::int32** site_flag,
85 @ac_google_namespace@::int32* site_default,
87 @ac_google_namespace@::int32 verbose_level);
89 #endif // BASE_VLOG_IS_ON_H_