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* Copyright 2004--2005, Google Inc.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// LOG(...) an ostream target that can be used to send formatted
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// output to a variety of logging targets, such as debugger console, stderr,
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// file, or any StreamInterface.
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// The severity level passed as the first argument to the LOGging
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// functions is used as a filter, to limit the verbosity of the logging.
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// Static members of LogMessage documented below are used to control the
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// verbosity and target of the output.
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// There are several variations on the LOG macro which facilitate logging
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// of common error conditions, detailed below.
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// LOG(sev) logs the given stream at severity "sev", which must be a
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// compile-time constant of the LoggingSeverity type, without the namespace
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// LOG_V(sev) Like LOG(), but sev is a run-time variable of the LoggingSeverity
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// type (basically, it just doesn't prepend the namespace).
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// LOG_F(sev) Like LOG(), but includes the name of the current function.
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// LOG_GLE(M)(sev [, mod]) attempt to add a string description of the
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// HRESULT returned by GetLastError. The "M" variant allows searching of a
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// DLL's string table for the error description.
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// LOG_ERRNO(sev) attempts to add a string description of an errno-derived
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// error. errno and associated facilities exist on both Windows and POSIX,
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// but on Windows they only apply to the C/C++ runtime.
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// LOG_ERR(sev) is an alias for the platform's normal error system, i.e. _GLE on
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// Windows and _ERRNO on POSIX.
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// (The above three also all have _EX versions that let you specify the error
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// code, rather than using the last one.)
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// LOG_E(sev, ctx, err, ...) logs a detailed error interpreted using the
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// LOG_CHECK_LEVEL(sev) (and LOG_CHECK_LEVEL_V(sev)) can be used as a test
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// before performing expensive or sensitive operations whose sole purpose is
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// to output logging data at the desired level.
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// Lastly, PLOG(sev, err) is an alias for LOG_ERR_EX.
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#ifndef TALK_BASE_LOGGING_H_
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#define TALK_BASE_LOGGING_H_
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#include "config.h" // NOLINT
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#include "talk/base/basictypes.h"
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#include "talk/base/criticalsection.h"
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class StreamInterface;
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///////////////////////////////////////////////////////////////////////////////
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// ConstantLabel can be used to easily generate string names from constant
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// values. This can be useful for logging descriptive names of error messages.
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// const ConstantLabel LIBRARY_ERRORS[] = {
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// KLABEL(SOME_ERROR),
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// KLABEL(SOME_OTHER_ERROR),
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// int err = LibraryFunc();
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// LOG(LS_ERROR) << "LibraryFunc returned: "
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// << ErrorName(err, LIBRARY_ERRORS);
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struct ConstantLabel { int value; const char * label; };
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#define KLABEL(x) { x, #x }
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#define TLABEL(x, y) { x, y }
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#define LASTLABEL { 0, 0 }
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const char * FindLabel(int value, const ConstantLabel entries[]);
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std::string ErrorName(int err, const ConstantLabel* err_table);
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//////////////////////////////////////////////////////////////////////
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// Note that the non-standard LoggingSeverity aliases exist because they are
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// still in broad use. The meanings of the levels are:
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// LS_SENSITIVE: Information which should only be logged with the consent
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// of the user, due to privacy concerns.
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// LS_VERBOSE: This level is for data which we do not want to appear in the
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// normal debug log, but should appear in diagnostic logs.
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// LS_INFO: Chatty level used in debugging for all sorts of things, the default
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// LS_WARNING: Something that may warrant investigation.
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// LS_ERROR: Something that should not have occurred.
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enum LoggingSeverity { LS_SENSITIVE, LS_VERBOSE, LS_INFO, LS_WARNING, LS_ERROR,
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WARNING = LS_WARNING,
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// LogErrorContext assists in interpreting the meaning of an error value.
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enum LogErrorContext {
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ERRCTX_ERRNO, // System-local errno
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ERRCTX_HRESULT, // Windows HRESULT
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ERRCTX_OSSTATUS, // MacOS OSStatus
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// Abbreviations for LOG_E macro
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ERRCTX_EN = ERRCTX_ERRNO, // LOG_E(sev, EN, x)
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ERRCTX_HR = ERRCTX_HRESULT, // LOG_E(sev, HR, x)
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ERRCTX_OS = ERRCTX_OSSTATUS, // LOG_E(sev, OS, x)
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static const int NO_LOGGING;
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LogMessage(const char* file, int line, LoggingSeverity sev,
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LogErrorContext err_ctx = ERRCTX_NONE, int err = 0,
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const char* module = NULL);
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static inline bool Loggable(LoggingSeverity sev) { return (sev >= min_sev_); }
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std::ostream& stream() { return print_stream_; }
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// Returns the time at which this function was called for the first time.
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// The time will be used as the logging start time.
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// If this is not called externally, the LogMessage ctor also calls it, in
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// which case the logging start time will be the time of the first LogMessage
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// instance is created.
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static uint32 LogStartTime();
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// These are attributes which apply to all logging channels
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// LogContext: Display the file and line number of the message
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static void LogContext(int min_sev);
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// LogThreads: Display the thread identifier of the current thread
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static void LogThreads(bool on = true);
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// LogTimestamps: Display the elapsed time of the program
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static void LogTimestamps(bool on = true);
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// These are the available logging channels
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// Debug: Debug console on Windows, otherwise stderr
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static void LogToDebug(int min_sev);
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static int GetLogToDebug() { return dbg_sev_; }
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// Stream: Any non-blocking stream interface. LogMessage takes ownership of
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// the stream. Multiple streams may be specified by using AddLogToStream.
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// LogToStream is retained for backwards compatibility; when invoked, it
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// will discard any previously set streams and install the specified stream.
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// GetLogToStream gets the severity for the specified stream, of if none
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// is specified, the minimum stream severity.
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// RemoveLogToStream removes the specified stream, without destroying it.
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static void LogToStream(StreamInterface* stream, int min_sev);
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static int GetLogToStream(StreamInterface* stream = NULL);
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static void AddLogToStream(StreamInterface* stream, int min_sev);
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static void RemoveLogToStream(StreamInterface* stream);
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// Testing against MinLogSeverity allows code to avoid potentially expensive
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// logging operations by pre-checking the logging level.
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static int GetMinLogSeverity() { return min_sev_; }
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static void SetDiagnosticMode(bool f) { is_diagnostic_mode_ = f; }
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static bool IsDiagnosticMode() { return is_diagnostic_mode_; }
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// Parses the provided parameter stream to configure the options above.
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// Useful for configuring logging from the command line. If file logging
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// is enabled, it is output to the specified filename.
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static void ConfigureLogging(const char* params, const char* filename);
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// Convert the string to a LS_ value; also accept numeric values.
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static int ParseLogSeverity(const std::string& value);
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typedef std::list<std::pair<StreamInterface*, int> > StreamList;
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// Updates min_sev_ appropriately when debug sinks change.
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static void UpdateMinLogSeverity();
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// These assist in formatting some parts of the debug output.
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static const char* Describe(LoggingSeverity sev);
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static const char* DescribeFile(const char* file);
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// These write out the actual log messages.
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static void OutputToDebug(const std::string& msg, LoggingSeverity severity_);
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static void OutputToStream(StreamInterface* stream, const std::string& msg);
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// The ostream that buffers the formatted message before output
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std::ostringstream print_stream_;
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// The severity level of this message
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LoggingSeverity severity_;
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// String data generated in the constructor, that should be appended to
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// the message before output.
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// Global lock for the logging subsystem
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static CriticalSection crit_;
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// dbg_sev_ is the thresholds for those output targets
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// min_sev_ is the minimum (most verbose) of those levels, and is used
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// as a short-circuit in the logging macros to identify messages that won't
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// ctx_sev_ is the minimum level at which file context is displayed
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static int min_sev_, dbg_sev_, ctx_sev_;
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// The output streams and their associated severities
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static StreamList streams_;
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// Flags for formatting options
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static bool thread_, timestamp_;
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// are we in diagnostic mode (as defined by the app)?
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static bool is_diagnostic_mode_;
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DISALLOW_EVIL_CONSTRUCTORS(LogMessage);
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//////////////////////////////////////////////////////////////////////
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//////////////////////////////////////////////////////////////////////
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class LogMultilineState {
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size_t unprintable_count_[2];
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LogMultilineState() {
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unprintable_count_[0] = unprintable_count_[1] = 0;
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// When possible, pass optional state variable to track various data across
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// multiple calls to LogMultiline. Otherwise, pass NULL.
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void LogMultiline(LoggingSeverity level, const char* label, bool input,
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const void* data, size_t len, bool hex_mode,
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LogMultilineState* state);
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//////////////////////////////////////////////////////////////////////
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// Macros which automatically disable logging when LOGGING == 0
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//////////////////////////////////////////////////////////////////////
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// If LOGGING is not explicitly defined, default to enabled in debug mode
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#if !defined(LOGGING)
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#if defined(_DEBUG) && !defined(NDEBUG)
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#endif // !defined(LOGGING)
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// The following non-obvious technique for implementation of a
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// conditional log stream was stolen from google3/base/logging.h.
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// This class is used to explicitly ignore values in the conditional
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// logging macros. This avoids compiler warnings like "value computed
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// is not used" and "statement has no effect".
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class LogMessageVoidify {
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LogMessageVoidify() { }
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// This has to be an operator with a precedence lower than << but
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void operator&(std::ostream&) { }
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#define LOG_SEVERITY_PRECONDITION(sev) \
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!(talk_base::LogMessage::Loggable(sev)) \
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: talk_base::LogMessageVoidify() &
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LOG_SEVERITY_PRECONDITION(talk_base::sev) \
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talk_base::LogMessage(__FILE__, __LINE__, talk_base::sev).stream()
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// The _V version is for when a variable is passed in. It doesn't do the
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// namespace concatination.
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LOG_SEVERITY_PRECONDITION(sev) \
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talk_base::LogMessage(__FILE__, __LINE__, sev).stream()
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// The _F version prefixes the message with the current function name.
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#if (defined(__GNUC__) && defined(_DEBUG)) || defined(WANT_PRETTY_LOG_F)
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#define LOG_F(sev) LOG(sev) << __PRETTY_FUNCTION__ << ": "
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#define LOG_F(sev) LOG(sev) << __FUNCTION__ << ": "
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#define LOG_CHECK_LEVEL(sev) \
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talk_base::LogCheckLevel(talk_base::sev)
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#define LOG_CHECK_LEVEL_V(sev) \
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talk_base::LogCheckLevel(sev)
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inline bool LogCheckLevel(LoggingSeverity sev) {
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return (LogMessage::GetMinLogSeverity() <= sev);
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#define LOG_E(sev, ctx, err, ...) \
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LOG_SEVERITY_PRECONDITION(talk_base::sev) \
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talk_base::LogMessage(__FILE__, __LINE__, talk_base::sev, \
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talk_base::ERRCTX_ ## ctx, err , ##__VA_ARGS__) \
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// Hopefully, the compiler will optimize away some of this code.
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// Note: syntax of "1 ? (void)0 : LogMessage" was causing errors in g++,
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// converted to "while (false)"
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while (false)talk_base:: LogMessage(NULL, 0, talk_base::sev).stream()
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while (false) talk_base::LogMessage(NULL, 0, sev).stream()
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#define LOG_F(sev) LOG(sev) << __FUNCTION__ << ": "
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#define LOG_CHECK_LEVEL(sev) \
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#define LOG_CHECK_LEVEL_V(sev) \
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#define LOG_E(sev, ctx, err, ...) \
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while (false) talk_base::LogMessage(__FILE__, __LINE__, talk_base::sev, \
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talk_base::ERRCTX_ ## ctx, err , ##__VA_ARGS__) \
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#define LOG_ERRNO_EX(sev, err) \
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LOG_E(sev, ERRNO, err)
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#define LOG_ERRNO(sev) \
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LOG_ERRNO_EX(sev, errno)
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#define LOG_GLE_EX(sev, err) \
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LOG_E(sev, HRESULT, err)
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#define LOG_GLE(sev) \
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LOG_GLE_EX(sev, GetLastError())
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#define LOG_GLEM(sev, mod) \
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LOG_E(sev, HRESULT, GetLastError(), mod)
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#define LOG_ERR_EX(sev, err) \
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#define LOG_ERR(sev) \
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#define LAST_SYSTEM_ERROR \
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#define LOG_ERR_EX(sev, err) \
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LOG_ERRNO_EX(sev, err)
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#define LOG_ERR(sev) \
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#define LAST_SYSTEM_ERROR \
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#define PLOG(sev, err) \
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// TODO(?): Add an "assert" wrapper that logs in the same manner.
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} // namespace talk_base
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#endif // TALK_BASE_LOGGING_H_