blob: 0089841d4e671513f7915068f519c207a4667ed9 [file] [log] [blame]
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
// This is a highly stripped-down version of libjingle's talk/base/logging.h.
// It is a thin wrapper around WEBRTC_TRACE, maintaining the libjingle log
// semantics to ease a transition to that format.
// NOTE: LS_INFO maps to a new trace level which should be reserved for
// infrequent, non-verbose logs. The other levels below kTraceWarning have been
// rendered essentially useless due to their verbosity. Carefully consider the
// impact of adding a new LS_INFO log. If it will be logged at anything
// approaching a frame or packet frequency, use LS_VERBOSE if necessary, or
// preferably, do not log at all.
// LOG(...) an ostream target that can be used to send formatted
// output to a variety of logging targets, such as debugger console, stderr,
// file, or any StreamInterface.
// The severity level passed as the first argument to the LOGging
// functions is used as a filter, to limit the verbosity of the logging.
// Static members of LogMessage documented below are used to control the
// verbosity and target of the output.
// There are several variations on the LOG macro which facilitate logging
// of common error conditions, detailed below.
// LOG(sev) logs the given stream at severity "sev", which must be a
// compile-time constant of the LoggingSeverity type, without the namespace
// prefix.
// LOG_V(sev) Like LOG(), but sev is a run-time variable of the LoggingSeverity
// type (basically, it just doesn't prepend the namespace).
// LOG_F(sev) Like LOG(), but includes the name of the current function.
#include <sstream>
namespace webrtc {
// Note that the non-standard LoggingSeverity aliases exist because they are
// still in broad use. The meanings of the levels are:
// LS_SENSITIVE: Information which should only be logged with the consent
// of the user, due to privacy concerns.
// LS_VERBOSE: This level is for data which we do not want to appear in the
// normal debug log, but should appear in diagnostic logs.
// LS_INFO: Chatty level used in debugging for all sorts of things, the default
// in debug builds.
// LS_WARNING: Something that may warrant investigation.
// LS_ERROR: Something that should not have occurred.
enum LoggingSeverity {
class LogMessage {
LogMessage(const char* file, int line, LoggingSeverity sev);
static bool Loggable(LoggingSeverity sev);
std::ostream& stream() { return print_stream_; }
// The ostream that buffers the formatted message before output
std::ostringstream print_stream_;
// The severity level of this message
LoggingSeverity severity_;
// Macros which automatically disable logging when WEBRTC_LOGGING == 0
#ifndef LOG
// The following non-obvious technique for implementation of a
// conditional log stream was stolen from google3/base/logging.h.
// This class is used to explicitly ignore values in the conditional
// logging macros. This avoids compiler warnings like "value computed
// is not used" and "statement has no effect".
class LogMessageVoidify {
LogMessageVoidify() { }
// This has to be an operator with a precedence lower than << but
// higher than ?:
void operator&(std::ostream&) { }
// This should compile away logs matching the following condition.
sev < webrtc::LS_INFO ? (void) 0 :
RESTRICT_LOGGING_PRECONDITION(sev) !(webrtc::LogMessage::Loggable(sev)) \
? (void) 0 \
: webrtc::LogMessageVoidify() &
#define LOG(sev) \
webrtc::LogMessage(__FILE__, __LINE__, webrtc::sev).stream()
// The _V version is for when a variable is passed in. It doesn't do the
// namespace concatination.
#define LOG_V(sev) \
webrtc::LogMessage(__FILE__, __LINE__, sev).stream()
// The _F version prefixes the message with the current function name.
#if (defined(__GNUC__) && !defined(NDEBUG)) || defined(WANT_PRETTY_LOG_F)
#define LOG_F(sev) LOG(sev) << __PRETTY_FUNCTION__ << ": "
#define LOG_F(sev) LOG(sev) << __FUNCTION__ << ": "
#endif // LOG
} // namespace webrtc