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log: allow dynamic updates of the global log level

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This commit is contained in:
Danny Robson 2017-01-31 20:30:38 +11:00
parent cc4f91f393
commit 256e1c32b3
2 changed files with 71 additions and 9 deletions
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50
log.cpp
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@ -54,6 +54,9 @@ ALL_LEVELS[] = {
static util::level_t
to_level (std::string name)
{
if (std::empty (name))
return util::EMERGENCY;
static const std::map<std::string, util::level_t> NAME_LEVELS = {
{ "EMERGENCY", util::EMERGENCY },
{ "ALERT", util::ALERT },
@ -106,8 +109,14 @@ util::operator<< (std::ostream& os, util::level_t l)
///////////////////////////////////////////////////////////////////////////////
static util::level_t
log_level (void)
// Determine what the value for LOG_LEVEL should be at the beginning of
// execution given the system environment.
//
// Note that the LOG macros _cannot_ be used from within this function as it
// will likely result in infinite recursion.
static
util::level_t
initial_log_level (void)
{
const char *env = getenv ("LOG_LEVEL");
if (!env)
@ -116,12 +125,42 @@ log_level (void)
try {
return to_level (env);
} catch (...) {
LOG_ERROR("Invalid environment LOG_LEVEL: '%s'", env);
std::clog << "Invalid environment LOG_LEVEL: '" << env << "'\n";
return util::DEFAULT_LOG_LEVEL;
}
}
//-----------------------------------------------------------------------------
// We shouldn't ever actually get to use the default value, but we set it to
// the most verbose option just in case we've made a mistake elsewhere.
static bool s_log_level_done;
static util::level_t s_log_level_value;
//-----------------------------------------------------------------------------
util::level_t
util::log_level (level_t _level)
{
s_log_level_value = _level;
s_log_level_done = true;
return s_log_level_value;
}
//-----------------------------------------------------------------------------
util::level_t
util::log_level (void)
{
if (!s_log_level_done) {
s_log_level_value = initial_log_level ();
s_log_level_done = true;
}
return s_log_level_value;
}
//-----------------------------------------------------------------------------
static bool
needs_break (util::level_t level)
@ -195,8 +234,7 @@ level_width (void)
void
util::log (util::level_t level, const std::string &msg)
{
static const util::level_t LOG_LEVEL = log_level ();
if (level <= LOG_LEVEL) {
if (level <= log_level ()) {
static const size_t time_len = strlen("YYYY-mm-dd HHMMhSS") + 1;
std::string time_string (time_len - 1, '\0');
time_t unix_time = time (nullptr);
@ -209,7 +247,7 @@ util::log (util::level_t level, const std::string &msg)
return;
}
std::cerr << time_string << " ["
std::clog << time_string << " ["
<< level_colour (level)
<< std::setw (trunc_cast<int> (level_width ()))
<< std::left

30
log.hpp
View File

@ -32,7 +32,6 @@ namespace util {
///////////////////////////////////////////////////////////////////////////
// rfc5424 log levels. It is assumed they are contiguous to simplify array
// indexing in logging code.
//
enum level_t {
EMERGENCY, /** system is unusable */
ALERT, /** action must be taken immediately */
@ -58,14 +57,39 @@ namespace util {
operator<< (std::ostream&, level_t);
///////////////////////////////////////////////////////////////////////////
// Query or set the global logging level filter. If the severity passed to
// a logging call is less than this then the output is discarded.
//
// The initial logging level can be controlled by setting the environment
// variable LOG_LEVEL to a string corresponding to the names of the values
// in level_t.
//
// Otherwise we fall back to the hard coded default from above.
//
// As a special case, a blank value for the environment variable LOG_LEVEL
// corresponds to the maximum log level. It indicates a preference for
// minimum output, and may be changed to disable all output in future
// updates.
level_t log_level (void);
level_t log_level (level_t);
///////////////////////////////////////////////////////////////////////////
void log (level_t, const std::string &msg);
template <typename ...Args, size_t N>
void log (level_t, const char (&fmt)[N], const Args&...);
void
log (level_t, const char (&fmt)[N], const Args&...);
//-------------------------------------------------------------------------
// Various convenience macros for logging specific strings with a well
// known severity.
//
// LOG_DEBUG is treated similarly to assert; if NDEBUG is defined then we
// compile out the statement so as to gain a little runtime efficiency
// speed.
#define LOG_EMERGENCY(...) do { util::log(util::EMERGENCY, ##__VA_ARGS__); } while (0)
#define LOG_ALERT(...) do { util::log(util::ALERT, ##__VA_ARGS__); } while (0)
#define LOG_CRITICAL(...) do { util::log(util::CRITICAL, ##__VA_ARGS__); } while (0)
@ -74,7 +98,7 @@ namespace util {
#define LOG_WARN(...) do { util::log(util::WARN, ##__VA_ARGS__); } while (0)
#define LOG_NOTICE(...) do { util::log(util::NOTICE, ##__VA_ARGS__); } while (0)
#define LOG_INFO(...) do { util::log(util::INFO, ##__VA_ARGS__); } while (0)
#if defined(ENABLE_DEBUGGING)
#if !defined(NDEBUG)
#define LOG_DEBUG(...) do { util::log(util::DEBUG, ##__VA_ARGS__); } while (0)
#else
#define LOG_DEBUG(...) do { ; } while (0)