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Adding setLogLevel feature #264

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Adding setLogLevel feature #264

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8b2e785
Adding setLogLevel feature
moleksy Nov 22, 2024
691cc1b
small fixes to description
moleksy Nov 22, 2024
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37 changes: 32 additions & 5 deletions media-proxy/include/mesh/logger.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@ enum class Level {
fatal
};

extern Level currentLogLevel;

class Formatter {
public:
virtual void formatMessage(std::ostringstream& ostream,
Expand Down Expand Up @@ -68,14 +70,14 @@ extern std::unique_ptr<Formatter> formatter;
class Logger {
public:
Logger(Level level, const char *format, va_list args);
Logger(Logger&& other) noexcept : ostream(std::move(other.ostream)) {}
Logger(Logger&& other) noexcept : level(other.level), ostream(std::move(other.ostream)) {}
Logger(const Logger&) = delete;
Logger& operator=(const Logger&) = delete;
~Logger();

template<typename T>
Logger& operator()(const char *key, const T& value) {
if (formatter)
if (formatter && level >= currentLogLevel)
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You still print the log message here no matter which log level is set, right? You only avoid formatter methods to be called if the level is disabled.

formatter->formatKeyValueBefore(ostream, key);

using DecayedT = std::decay_t<T>;
Expand All @@ -88,12 +90,13 @@ class Logger {
else
ostream << value;

if (formatter)
if (formatter && level >= currentLogLevel)
formatter->formatKeyValueAfter(ostream, key);
return *this;
}

private:
Level level;
std::ostringstream ostream;
};

Expand Down Expand Up @@ -130,6 +133,31 @@ class Logger {
* {"time":"2024-11-15T00:27:30.300Z","level":"error","msg":"High load","percent":99.8,"num_clients":9801}
* {"time":"2024-11-15T00:27:30.300Z","level":"debug","msg":"Counter incremented","cnt":355}
* {"time":"2024-11-15T00:27:30.300Z","level":"fatal","msg":"Emergency exit","err_code":312645}
* Example C: Setting the log level dynamically
* ============================================
* mesh::log::setLogLevel(mesh::log::Level::warn); // Set minimum log level to WARN
*
* log::info("This message will not be displayed")("id", "123456");
* log::warn("Low memory warning")("available_mb", 512);
* log::error("Critical error occurred")("error_code", 5001);
* log::debug("Debugging details")("step", "init");
*
* Output:
* Nov 15 00:26:07.672 [WARN] Low memory warning available_mb=512
* Nov 15 00:26:07.672 [ERRO] Critical error occurred error_code=5001
* Nov 15 00:26:07.672 [DEBU] Debugging details step=init
* Example D: Adjusting log levels during runtime
* ==============================================
* mesh::log::setLogLevel(mesh::log::Level::info); // Enable all log messages
* log::info("Re-enabled info logging")("reason", "debugging mode");
*
* Output:
* Nov 15 00:26:07.672 [INFO] Re-enabled info logging reason="debugging mode"
*
* Features:
* - Use `mesh::log::setLogLevel(mesh::log::Level)` to dynamically adjust log filtering.
* - Supported log levels: `info`, `warn`, `error`, `debug`, `fatal`.
* - Messages below the set log level will be ignored.
*/
Logger info(const char* format, ...);
Logger warn(const char* format, ...);
Expand All @@ -138,8 +166,7 @@ Logger debug(const char* format, ...);
Logger fatal(const char* format, ...);

void setFormatter(std::unique_ptr<Formatter> new_formatter);

// TODO: Add an option to set the log level.
void setLogLevel(Level level);

} // namespace mesh::log

Expand Down
19 changes: 12 additions & 7 deletions media-proxy/src/mesh/logger.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@

namespace mesh::log {

Level currentLogLevel = Level::info;

void StandardFormatter::formatMessage(std::ostringstream& ostream, Level level,
const char *format, va_list args)
{
Expand Down Expand Up @@ -113,21 +115,24 @@ void setFormatter(std::unique_ptr<Formatter> new_formatter)
formatter = std::move(new_formatter);
}

void setLogLevel(Level level) {
currentLogLevel = level;
}
Comment on lines +118 to +120
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This function is not thread-safe. Since there is no meaning in changing the log level at runtime, I suggest to leave this function as it is but say in the comment block that this is to be called only once the logger is created in the app.

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Actually there was a meaning for me - for different tests I wanted to have control over what is visible where, I'll make it thread safe.

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If you make it thread safe, you'll make currentLogLevel thread safe. It will add latency to printing messages. Please don't.


Logger::Logger(Level level, const char *format, va_list args)
{
if (formatter) {
if (level >= currentLogLevel && formatter) {
formatter->formatBefore(ostream);
formatter->formatMessage(ostream, level, format, args);
}
}

Logger::~Logger()
{
if (formatter)
formatter->formatAfter(ostream);

if (!ostream.str().empty())
Logger::~Logger() {
if (!ostream.str().empty() && level >= currentLogLevel) {
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Suggested change
if (!ostream.str().empty() && level >= currentLogLevel) {
if (level >= currentLogLevel && !ostream.str().empty()) {

if (formatter)
formatter->formatAfter(ostream);
std::cout << ostream.str() << std::endl;
}
}

Logger info(const char* format, ...)
Expand Down