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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#pragma once
#include <string>
#include <cstring>
#include <sstream>
#include "base/base_api.h"
#include "base/basictypes.h"
#include "build/build_config.h"
// Optional message capabilities
// -----------------------------
// Assertion failed messages and fatal errors are displayed in a dialog box
// before the application exits. However, running this UI creates a message
// loop, which causes application messages to be processed and potentially
// dispatched to existing application windows. Since the application is in a
// bad state when this assertion dialog is displayed, these messages may not
// get processed and hang the dialog, or the application might go crazy.
// Therefore, it can be beneficial to display the error dialog in a separate
// process from the main application. When the logging system needs to display
// a fatal error dialog box, it will look for a program called
// "DebugMessage.exe" in the same directory as the application executable. It
// will run this application with the message as the command line, and will
// not include the name of the application as is traditional for easier
// parsing.
// The code for DebugMessage.exe is only one line. In WinMain, do:
// MessageBox(NULL, GetCommandLineW(), L"Fatal Error", 0);
// If DebugMessage.exe is not found, the logging code will use a normal
// MessageBox, potentially causing the problems discussed above.
// Instructions
// ------------
// Make a bunch of macros for logging. The way to log things is to stream
// things to LOG(<a particular severity level>). E.g.,
// LOG(INFO) << "Found " << num_cookies << " cookies";
// You can also do conditional logging:
// LOG_IF(INFO, num_cookies > 10) << "Got lots of cookies";
// The above will cause log messages to be output on the 1st, 11th, 21st, ...
// times it is executed. Note that the special COUNTER value is used to
// identify which repetition is happening.
// The CHECK(condition) macro is active in both debug and release builds and
// effectively performs a LOG(FATAL) which terminates the process and
// generates a crashdump unless a debugger is attached.
// There are also "debug mode" logging macros like the ones above:
// DLOG(INFO) << "Found cookies";
// DLOG_IF(INFO, num_cookies > 10) << "Got lots of cookies";
// All "debug mode" logging is compiled away to nothing for non-debug mode
// compiles. LOG_IF and development flags also work well together
// because the code can be compiled away sometimes.
// We also have
// LOG_ASSERT(assertion);
// DLOG_ASSERT(assertion);
// which is syntactic sugar for {,D}LOG_IF(FATAL, assert fails) << assertion;
// There are "verbose level" logging macros. They look like
// VLOG(1) << "I'm printed when you run the program with --v=1 or more";
// VLOG(2) << "I'm printed when you run the program with --v=2 or more";
// These always log at the INFO log level (when they log at all).
// The verbose logging can also be turned on module-by-module. For instance,
// --vmodule=profile=2,icon_loader=1,browser_*=3,*/chromeos/*=4 --v=0
// will cause:
// a. VLOG(2) and lower messages to be printed from profile.{h,cc}
// b. VLOG(1) and lower messages to be printed from icon_loader.{h,cc}
// c. VLOG(3) and lower messages to be printed from files prefixed with
// "browser"
// d. VLOG(4) and lower messages to be printed from files under a
// "chromeos" directory.
// e. VLOG(0) and lower messages to be printed from elsewhere
// The wildcarding functionality shown by (c) supports both '*' (match
// 0 or more characters) and '?' (match any single character)
// wildcards. Any pattern containing a forward or backward slash will
// be tested against the whole pathname and not just the module.
// E.g., "*/foo/bar/*=2" would change the logging level for all code
// in source files under a "foo/bar" directory.
// There's also VLOG_IS_ON(n) "verbose level" condition macro. To be used as
// if (VLOG_IS_ON(2)) {
// // do some logging preparation and logging
// // that can't be accomplished with just VLOG(2) << ...;
// }
// There is also a VLOG_IF "verbose level" condition macro for sample
// cases, when some extra computation and preparation for logs is not
// needed.
// VLOG_IF(1, (size > 1024))
// << "I'm printed when size is more than 1024 and when you run the "
// "program with --v=1 or more";
// We also override the standard 'assert' to use 'DLOG_ASSERT'.
// Lastly, there is:
// PLOG(ERROR) << "Couldn't do foo";
// DPLOG(ERROR) << "Couldn't do foo";
// PLOG_IF(ERROR, cond) << "Couldn't do foo";
// DPLOG_IF(ERROR, cond) << "Couldn't do foo";
// PCHECK(condition) << "Couldn't do foo";
// DPCHECK(condition) << "Couldn't do foo";
// which append the last system error to the message in string form (taken from
// GetLastError() on Windows and errno on POSIX).
// The supported severity levels for macros that allow you to specify one
// are (in increasing order of severity) INFO, WARNING, ERROR, ERROR_REPORT,
// and FATAL.
// Very important: logging a message at the FATAL severity level causes
// the program to terminate (after the message is logged).
// Note the special severity of ERROR_REPORT only available/relevant in normal
// mode, which displays error dialog without terminating the program. There is
// no error dialog for severity ERROR or below in normal mode.
// There is also the special severity of DFATAL, which logs FATAL in
// debug mode, ERROR in normal mode.
namespace logging {
// Where to record logging output? A flat file and/or system debug log via
// OutputDebugString. Defaults on Windows to LOG_ONLY_TO_FILE, and on
enum LoggingDestination { LOG_NONE,
// Indicates that the log file should be locked when being written to.
// Often, there is no locking, which is fine for a single threaded program.
// If logging is being done from multiple threads or there can be more than
// one process doing the logging, the file should be locked during writes to
// make each log outut atomic. Other writers will block.
// All processes writing to the log file must have their locking set for it to
// work properly. Defaults to DONT_LOCK_LOG_FILE.
enum LogLockingState { LOCK_LOG_FILE, DONT_LOCK_LOG_FILE };
// On startup, should we delete or append to an existing log file (if any)?
// Defaults to APPEND_TO_OLD_LOG_FILE.
enum DcheckState {
// TODO(avi): do we want to do a unification of character types here?
#if defined(OS_WIN)
typedef wchar_t PathChar;
typedef char PathChar;
// Define different names for the BaseInitLoggingImpl() function depending on
// whether NDEBUG is defined or not so that we'll fail to link if someone tries
// to compile with NDEBUG but includes logging.h without defining it,
// or vice versa.
#define BaseInitLoggingImpl BaseInitLoggingImpl_built_with_NDEBUG
#define BaseInitLoggingImpl BaseInitLoggingImpl_built_without_NDEBUG
// Implementation of the InitLogging() method declared below. We use a
// more-specific name so we can #define it above without affecting other code
// that has named stuff "InitLogging".
BASE_API bool BaseInitLoggingImpl(const PathChar* log_file,
LoggingDestination logging_dest,
LogLockingState lock_log,
OldFileDeletionState delete_old,
DcheckState dcheck_state);
// Sets the log file name and other global logging state. Calling this function
// is recommended, and is normally done at the beginning of application init.
// If you don't call it, all the flags will be initialized to their default
// values, and there is a race condition that may leak a critical section
// object if two threads try to do the first log at the same time.
// See the definition of the enums above for descriptions and default values.
// The default log file is initialized to "debug.log" in the application
// directory. You probably don't want this, especially since the program
// directory may not be writable on an enduser's system.
inline bool InitLogging(const PathChar* log_file,
LoggingDestination logging_dest,
LogLockingState lock_log,
OldFileDeletionState delete_old,
DcheckState dcheck_state) {
return BaseInitLoggingImpl(log_file, logging_dest, lock_log,
delete_old, dcheck_state);
// Sets the log level. Anything at or above this level will be written to the
// log file/displayed to the user (if applicable). Anything below this level
// will be silently ignored. The log level defaults to 0 (everything is logged
// up to level INFO) if this function is not called.
// Note that log messages for VLOG(x) are logged at level -x, so setting
// the min log level to negative values enables verbose logging.
BASE_API void SetMinLogLevel(int level);
// Gets the current log level.
BASE_API int GetMinLogLevel();
// Gets the VLOG default verbosity level.
BASE_API int GetVlogVerbosity();
// Gets the current vlog level for the given file (usually taken from
// __FILE__).
// Note that |N| is the size *with* the null terminator.
BASE_API int GetVlogLevelHelper(const char* file_start, size_t N);
template <size_t N>
int GetVlogLevel(const char (&file)[N]) {
return GetVlogLevelHelper(file, N);
// Sets the common items you want to be prepended to each log message.
// process and thread IDs default to off, the timestamp defaults to on.
// If this function is not called, logging defaults to writing the timestamp
// only.
BASE_API void SetLogItems(bool enable_process_id, bool enable_thread_id,
bool enable_timestamp, bool enable_tickcount);
// Sets whether or not you'd like to see fatal debug messages popped up in
// a dialog box or not.
// Dialogs are not shown by default.
BASE_API void SetShowErrorDialogs(bool enable_dialogs);
// Sets the Log Assert Handler that will be used to notify of check failures.
// The default handler shows a dialog box and then terminate the process,
// however clients can use this function to override with their own handling
// (e.g. a silent one for Unit Tests)
typedef void (*LogAssertHandlerFunction)(const std::string& str);
BASE_API void SetLogAssertHandler(LogAssertHandlerFunction handler);
// Sets the Log Report Handler that will be used to notify of check failures
// in non-debug mode. The default handler shows a dialog box and continues
// the execution, however clients can use this function to override with their
// own handling.
typedef void (*LogReportHandlerFunction)(const std::string& str);
BASE_API void SetLogReportHandler(LogReportHandlerFunction handler);
// Sets the Log Message Handler that gets passed every log message before
// it's sent to other log destinations (if any).
// Returns true to signal that it handled the message and the message
// should not be sent to other log destinations.
typedef bool (*LogMessageHandlerFunction)(int severity,
const char* file, int line, size_t message_start, const std::string& str);
BASE_API void SetLogMessageHandler(LogMessageHandlerFunction handler);
BASE_API LogMessageHandlerFunction GetLogMessageHandler();
typedef int LogSeverity;
const LogSeverity LOG_VERBOSE = -1; // This is level 1 verbosity
// Note: the log severities are used to index into the array of names,
// see log_severity_names.
const LogSeverity LOG_INFO = 0;
const LogSeverity LOG_WARNING = 1;
const LogSeverity LOG_ERROR = 2;
const LogSeverity LOG_ERROR_REPORT = 3;
const LogSeverity LOG_FATAL = 4;
const LogSeverity LOG_NUM_SEVERITIES = 5;
// LOG_DFATAL is LOG_FATAL in debug mode, ERROR in normal mode
#ifdef NDEBUG
const LogSeverity LOG_DFATAL = LOG_ERROR;
const LogSeverity LOG_DFATAL = LOG_FATAL;
// A few definitions of macros that don't generate much code. These are used
// by LOG() and LOG_IF, etc. Since these are used all over our code, it's
// better to have compact code for these operations.
#define COMPACT_GOOGLE_LOG_EX_INFO(ClassName, ...) \
logging::ClassName(__FILE__, __LINE__, logging::LOG_INFO , ##__VA_ARGS__)
#define COMPACT_GOOGLE_LOG_EX_WARNING(ClassName, ...) \
logging::ClassName(__FILE__, __LINE__, logging::LOG_WARNING , ##__VA_ARGS__)
#define COMPACT_GOOGLE_LOG_EX_ERROR(ClassName, ...) \
logging::ClassName(__FILE__, __LINE__, logging::LOG_ERROR , ##__VA_ARGS__)
logging::ClassName(__FILE__, __LINE__, \
logging::LOG_ERROR_REPORT , ##__VA_ARGS__)
#define COMPACT_GOOGLE_LOG_EX_FATAL(ClassName, ...) \
logging::ClassName(__FILE__, __LINE__, logging::LOG_FATAL , ##__VA_ARGS__)
#define COMPACT_GOOGLE_LOG_EX_DFATAL(ClassName, ...) \
logging::ClassName(__FILE__, __LINE__, logging::LOG_DFATAL , ##__VA_ARGS__)
// wingdi.h defines ERROR to be 0. When we call LOG(ERROR), it gets
// substituted with 0, and it expands to COMPACT_GOOGLE_LOG_0. To allow us
// to keep using this syntax, we define this macro to do the same thing
// as COMPACT_GOOGLE_LOG_ERROR, and also define ERROR the same way that
// the Windows SDK does for consistency.
#define ERROR 0
#define COMPACT_GOOGLE_LOG_EX_0(ClassName, ...) \
// Needed for LOG_IS_ON(ERROR).
const LogSeverity LOG_0 = LOG_ERROR;
// As special cases, we can assume that LOG_IS_ON(ERROR_REPORT) and
// LOG_IS_ON(FATAL) always hold. Also, LOG_IS_ON(DFATAL) always holds
// in debug mode. In particular, CHECK()s will always fire if they
// fail.
#define LOG_IS_ON(severity) \
((::logging::LOG_ ## severity) >= ::logging::GetMinLogLevel())
// We can't do any caching tricks with VLOG_IS_ON() like the
// google-glog version since it requires GCC extensions. This means
// that using the v-logging functions in conjunction with --vmodule
// may be slow.
#define VLOG_IS_ON(verboselevel) \
((verboselevel) <= ::logging::GetVlogLevel(__FILE__))
// Helper macro which avoids evaluating the arguments to a stream if
// the condition doesn't hold.
#define LAZY_STREAM(stream, condition) \
!(condition) ? (void) 0 : ::logging::LogMessageVoidify() & (stream)
// We use the preprocessor's merging operator, "##", so that, e.g.,
// LOG(INFO) becomes the token COMPACT_GOOGLE_LOG_INFO. There's some funny
// subtle difference between ostream member streaming functions (e.g.,
// ostream::operator<<(int) and ostream non-member streaming functions
// (e.g., ::operator<<(ostream&, string&): it turns out that it's
// impossible to stream something like a string directly to an unnamed
// ostream. We employ a neat hack by calling the stream() member
// function of LogMessage which seems to avoid the problem.
#define LOG_STREAM(severity) COMPACT_GOOGLE_LOG_ ##
#define LOG(severity) LAZY_STREAM(LOG_STREAM(severity), LOG_IS_ON(severity))
#define LOG_IF(severity, condition) \
LAZY_STREAM(LOG_STREAM(severity), LOG_IS_ON(severity) && (condition))
#define SYSLOG(severity) LOG(severity)
#define SYSLOG_IF(severity, condition) LOG_IF(severity, condition)
// The VLOG macros log with negative verbosities.
#define VLOG_STREAM(verbose_level) \
logging::LogMessage(__FILE__, __LINE__, -verbose_level).stream()
#define VLOG(verbose_level) \
LAZY_STREAM(VLOG_STREAM(verbose_level), VLOG_IS_ON(verbose_level))
#define VLOG_IF(verbose_level, condition) \
LAZY_STREAM(VLOG_STREAM(verbose_level), \
VLOG_IS_ON(verbose_level) && (condition))
#if defined (OS_WIN)
#define VPLOG_STREAM(verbose_level) \
logging::Win32ErrorLogMessage(__FILE__, __LINE__, -verbose_level, \
#elif defined(OS_POSIX)
#define VPLOG_STREAM(verbose_level) \
logging::ErrnoLogMessage(__FILE__, __LINE__, -verbose_level, \
#define VPLOG(verbose_level) \
LAZY_STREAM(VPLOG_STREAM(verbose_level), VLOG_IS_ON(verbose_level))
#define VPLOG_IF(verbose_level, condition) \
LAZY_STREAM(VPLOG_STREAM(verbose_level), \
VLOG_IS_ON(verbose_level) && (condition))
// TODO(akalin): Add more VLOG variants, e.g. VPLOG.
#define LOG_ASSERT(condition) \
LOG_IF(FATAL, !(condition)) << "Assert failed: " #condition ". "
#define SYSLOG_ASSERT(condition) \
SYSLOG_IF(FATAL, !(condition)) << "Assert failed: " #condition ". "
#if defined(OS_WIN)
#define LOG_GETLASTERROR_STREAM(severity) \
COMPACT_GOOGLE_LOG_EX_ ## severity(Win32ErrorLogMessage, \
#define LOG_GETLASTERROR(severity) \
#define LOG_GETLASTERROR_MODULE_STREAM(severity, module) \
COMPACT_GOOGLE_LOG_EX_ ## severity(Win32ErrorLogMessage, \
::logging::GetLastSystemErrorCode(), module).stream()
#define LOG_GETLASTERROR_MODULE(severity, module) \
// PLOG_STREAM is used by PLOG, which is the usual error logging macro
// for each platform.
#define PLOG_STREAM(severity) LOG_GETLASTERROR_STREAM(severity)
#elif defined(OS_POSIX)
#define LOG_ERRNO_STREAM(severity) \
COMPACT_GOOGLE_LOG_EX_ ## severity(ErrnoLogMessage, \
#define LOG_ERRNO(severity) \
// PLOG_STREAM is used by PLOG, which is the usual error logging macro
// for each platform.
#define PLOG_STREAM(severity) LOG_ERRNO_STREAM(severity)
// TODO(tschmelcher): Should we add OSStatus logging for Mac?
#define PLOG(severity) \
LAZY_STREAM(PLOG_STREAM(severity), LOG_IS_ON(severity))
#define PLOG_IF(severity, condition) \
LAZY_STREAM(PLOG_STREAM(severity), LOG_IS_ON(severity) && (condition))
// CHECK dies with a fatal error if condition is not true. It is *not*
// controlled by NDEBUG, so the check will be executed regardless of
// compilation mode.
// We make sure CHECK et al. always evaluates their arguments, as
// doing CHECK(FunctionWithSideEffect()) is a common idiom.
#define CHECK(condition) \
<< "Check failed: " #condition ". "
#define PCHECK(condition) \
<< "Check failed: " #condition ". "
// Build the error message string. This is separate from the "Impl"
// function template because it is not performance critical and so can
// be out of line, while the "Impl" code should be inline. Caller
// takes ownership of the returned string.
template<class t1, class t2>
#ifdef ANDROID
std::string* MakeCheckOpString(const t1& v1, const t2& v2, const char* names) {
std::ostringstream ss;
ss << names << " (" << v1 << " vs. " << v2 << ")";
std::string* msg = new std::string(ss.str());
return msg;
// MSVC doesn't like complex extern templates and DLLs.
#if !defined(COMPILER_MSVC)
// Commonly used instantiations of MakeCheckOpString<>. Explicitly instantiated
// in
extern template std::string* MakeCheckOpString<int, int>(
const int&, const int&, const char* names);
extern template std::string* MakeCheckOpString<unsigned long, unsigned long>(
const unsigned long&, const unsigned long&, const char* names);
extern template std::string* MakeCheckOpString<unsigned long, unsigned int>(
const unsigned long&, const unsigned int&, const char* names);
extern template std::string* MakeCheckOpString<unsigned int, unsigned long>(
const unsigned int&, const unsigned long&, const char* names);
extern template std::string* MakeCheckOpString<std::string, std::string>(
const std::string&, const std::string&, const char* name);
// Helper macro for binary operators.
// Don't use this macro directly in your code, use CHECK_EQ et al below.
// TODO(akalin): Rewrite this so that constructs like if (...)
// CHECK_EQ(...) else { ... } work properly.
#define CHECK_OP(name, op, val1, val2) \
if (std::string* _result = \
logging::Check##name##Impl((val1), (val2), \
#val1 " " #op " " #val2)) \
logging::LogMessage(__FILE__, __LINE__, _result).stream()
// Helper functions for CHECK_OP macro.
// The (int, int) specialization works around the issue that the compiler
// will not instantiate the template version of the function on values of
// unnamed enum type - see comment below.
#define DEFINE_CHECK_OP_IMPL(name, op) \
template <class t1, class t2> \
inline std::string* Check##name##Impl(const t1& v1, const t2& v2, \
const char* names) { \
if (v1 op v2) return NULL; \
else return MakeCheckOpString(v1, v2, names); \
} \
inline std::string* Check##name##Impl(int v1, int v2, const char* names) { \
if (v1 op v2) return NULL; \
else return MakeCheckOpString(v1, v2, names); \
#define CHECK_EQ(val1, val2) CHECK_OP(EQ, ==, val1, val2)
#define CHECK_NE(val1, val2) CHECK_OP(NE, !=, val1, val2)
#define CHECK_LE(val1, val2) CHECK_OP(LE, <=, val1, val2)
#define CHECK_LT(val1, val2) CHECK_OP(LT, < , val1, val2)
#define CHECK_GE(val1, val2) CHECK_OP(GE, >=, val1, val2)
#define CHECK_GT(val1, val2) CHECK_OP(GT, > , val1, val2)
// is open for a real fix for this. For now, Windows
// uses OFFICIAL_BUILD and other platforms use the branding flag when NDEBUG is
// defined.
#if ( defined(OS_WIN) && defined(OFFICIAL_BUILD)) || \
(!defined(OS_WIN) && defined(NDEBUG) && defined(GOOGLE_CHROME_BUILD))
// Used by unit tests.
// In order to have optimized code for official builds, remove DLOGs and
#define ENABLE_DLOG 0
#elif defined(NDEBUG)
// Otherwise, if we're a release build, remove DLOGs but not DCHECKs
// (since those can still be turned on via a command-line flag).
#define ENABLE_DLOG 0
// Otherwise, we're a debug build so enable DLOGs and DCHECKs.
#define ENABLE_DLOG 1
// Definitions for DLOG et al.
#define DLOG_IS_ON(severity) LOG_IS_ON(severity)
#define DLOG_IF(severity, condition) LOG_IF(severity, condition)
#define DLOG_ASSERT(condition) LOG_ASSERT(condition)
#define DPLOG_IF(severity, condition) PLOG_IF(severity, condition)
#define DVLOG_IF(verboselevel, condition) VLOG_IF(verboselevel, condition)
#define DVPLOG_IF(verboselevel, condition) VPLOG_IF(verboselevel, condition)
#else // ENABLE_DLOG
// If ENABLE_DLOG is off, we want to avoid emitting any references to
// |condition| (which may reference a variable defined only if NDEBUG
// is not defined). Contrast this with DCHECK et al., which has
// different behavior.
true ? (void) 0 : ::logging::LogMessageVoidify() & LOG_STREAM(FATAL)
#define DLOG_IS_ON(severity) false
#define DLOG_IF(severity, condition) DLOG_EAT_STREAM_PARAMETERS
#define DPLOG_IF(severity, condition) DLOG_EAT_STREAM_PARAMETERS
#define DVLOG_IF(verboselevel, condition) DLOG_EAT_STREAM_PARAMETERS
#define DVPLOG_IF(verboselevel, condition) DLOG_EAT_STREAM_PARAMETERS
#endif // ENABLE_DLOG
// DEBUG_MODE is for uses like
// if (DEBUG_MODE) foo.CheckThatFoo();
// instead of
// #ifndef NDEBUG
// foo.CheckThatFoo();
// #endif
// We tie its state to ENABLE_DLOG.
#define DLOG(severity) \
LAZY_STREAM(LOG_STREAM(severity), DLOG_IS_ON(severity))
#if defined(OS_WIN)
#define DLOG_GETLASTERROR(severity) \
#define DLOG_GETLASTERROR_MODULE(severity, module) \
#elif defined(OS_POSIX)
#define DLOG_ERRNO(severity) \
#define DPLOG(severity) \
LAZY_STREAM(PLOG_STREAM(severity), DLOG_IS_ON(severity))
#define DVLOG(verboselevel) DLOG_IF(INFO, VLOG_IS_ON(verboselevel))
#define DVPLOG(verboselevel) DVPLOG_IF(verboselevel, VLOG_IS_ON(verboselevel))
// Definitions for DCHECK et al.
#if defined(NDEBUG)
#define COMPACT_GOOGLE_LOG_EX_DCHECK(ClassName, ...) \
extern DcheckState g_dcheck_state;
#define DCHECK_IS_ON() \
((::logging::g_dcheck_state == \
#else // defined(NDEBUG)
// On a regular debug build, we want to have DCHECKs enabled.
#define COMPACT_GOOGLE_LOG_EX_DCHECK(ClassName, ...) \
const LogSeverity LOG_DCHECK = LOG_FATAL;
#define DCHECK_IS_ON() true
#endif // defined(NDEBUG)
// These are just dummy values since DCHECK_IS_ON() is always false in
// this case.
#define COMPACT_GOOGLE_LOG_EX_DCHECK(ClassName, ...) \
const LogSeverity LOG_DCHECK = LOG_INFO;
#define DCHECK_IS_ON() false
// DCHECK et al. make sure to reference |condition| regardless of
// whether DCHECKs are enabled; this is so that we don't get unused
// variable warnings if the only use of a variable is in a DCHECK.
// This behavior is different from DLOG_IF et al.
#define DCHECK(condition) \
<< "Check failed: " #condition ". "
#define DPCHECK(condition) \
<< "Check failed: " #condition ". "
// Helper macro for binary operators.
// Don't use this macro directly in your code, use DCHECK_EQ et al below.
#define DCHECK_OP(name, op, val1, val2) \
if (DCHECK_IS_ON()) \
if (std::string* _result = \
logging::Check##name##Impl((val1), (val2), \
#val1 " " #op " " #val2)) \
logging::LogMessage( \
__FILE__, __LINE__, ::logging::LOG_DCHECK, \
// Equality/Inequality checks - compare two values, and log a
// LOG_DCHECK message including the two values when the result is not
// as expected. The values must have operator<<(ostream, ...)
// defined.
// You may append to the error message like so:
// DCHECK_NE(1, 2) << ": The world must be ending!";
// We are very careful to ensure that each argument is evaluated exactly
// once, and that anything which is legal to pass as a function argument is
// legal here. In particular, the arguments may be temporary expressions
// which will end up being destroyed at the end of the apparent statement,
// for example:
// DCHECK_EQ(string("abc")[1], 'b');
// WARNING: These may not compile correctly if one of the arguments is a pointer
// and the other is NULL. To work around this, simply static_cast NULL to the
// type of the desired pointer.
#define DCHECK_EQ(val1, val2) DCHECK_OP(EQ, ==, val1, val2)
#define DCHECK_NE(val1, val2) DCHECK_OP(NE, !=, val1, val2)
#define DCHECK_LE(val1, val2) DCHECK_OP(LE, <=, val1, val2)
#define DCHECK_LT(val1, val2) DCHECK_OP(LT, < , val1, val2)
#define DCHECK_GE(val1, val2) DCHECK_OP(GE, >=, val1, val2)
#define DCHECK_GT(val1, val2) DCHECK_OP(GT, > , val1, val2)
#define NOTREACHED() DCHECK(false)
// Redefine the standard assert to use our nice log files
#undef assert
#define assert(x) DLOG_ASSERT(x)
// This class more or less represents a particular log message. You
// create an instance of LogMessage and then stream stuff to it.
// When you finish streaming to it, ~LogMessage is called and the
// full message gets streamed to the appropriate destination.
// You shouldn't actually use LogMessage's constructor to log things,
// though. You should use the LOG() macro (and variants thereof)
// above.
class BASE_API LogMessage {
LogMessage(const char* file, int line, LogSeverity severity, int ctr);
// Two special constructors that generate reduced amounts of code at
// LOG call sites for common cases.
// Used for LOG(INFO): Implied are:
// severity = LOG_INFO, ctr = 0
// Using this constructor instead of the more complex constructor above
// saves a couple of bytes per call site.
LogMessage(const char* file, int line);
// Used for LOG(severity) where severity != INFO. Implied
// are: ctr = 0
// Using this constructor instead of the more complex constructor above
// saves a couple of bytes per call site.
LogMessage(const char* file, int line, LogSeverity severity);
// A special constructor used for check failures. Takes ownership
// of the given string.
// Implied severity = LOG_FATAL
LogMessage(const char* file, int line, std::string* result);
// A special constructor used for check failures, with the option to
// specify severity. Takes ownership of the given string.
LogMessage(const char* file, int line, LogSeverity severity,
std::string* result);
std::ostream& stream() { return stream_; }
void Init(const char* file, int line);
LogSeverity severity_;
std::ostringstream stream_;
size_t message_start_; // Offset of the start of the message (past prefix
// info).
// The file and line information passed in to the constructor.
const char* file_;
const int line_;
#if defined(OS_WIN)
// Stores the current value of GetLastError in the constructor and restores
// it in the destructor by calling SetLastError.
// This is useful since the LogMessage class uses a lot of Win32 calls
// that will lose the value of GLE and the code that called the log function
// will have lost the thread error value when the log call returns.
class SaveLastError {
unsigned long get_error() const { return last_error_; }
unsigned long last_error_;
SaveLastError last_error_;
// A non-macro interface to the log facility; (useful
// when the logging level is not a compile-time constant).
inline void LogAtLevel(int const log_level, std::string const &msg) {
LogMessage(__FILE__, __LINE__, log_level).stream() << msg;
// 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 BASE_API LogMessageVoidify {
LogMessageVoidify() { }
// This has to be an operator with a precedence lower than << but
// higher than ?:
void operator&(std::ostream&) { }
#if defined(OS_WIN)
typedef unsigned long SystemErrorCode;
#elif defined(OS_POSIX)
typedef int SystemErrorCode;
// Alias for ::GetLastError() on Windows and errno on POSIX. Avoids having to
// pull in windows.h just for GetLastError() and DWORD.
BASE_API SystemErrorCode GetLastSystemErrorCode();
#if defined(OS_WIN)
// Appends a formatted system message of the GetLastError() type.
class BASE_API Win32ErrorLogMessage {
Win32ErrorLogMessage(const char* file,
int line,
LogSeverity severity,
SystemErrorCode err,
const char* module);
Win32ErrorLogMessage(const char* file,
int line,
LogSeverity severity,
SystemErrorCode err);
// Appends the error message before destructing the encapsulated class.
std::ostream& stream() { return; }
SystemErrorCode err_;
// Optional name of the module defining the error.
const char* module_;
LogMessage log_message_;
#elif defined(OS_POSIX)
// Appends a formatted system message of the errno type
class ErrnoLogMessage {
ErrnoLogMessage(const char* file,
int line,
LogSeverity severity,
SystemErrorCode err);
// Appends the error message before destructing the encapsulated class.
std::ostream& stream() { return; }
SystemErrorCode err_;
LogMessage log_message_;
#endif // OS_WIN
// Closes the log file explicitly if open.
// NOTE: Since the log file is opened as necessary by the action of logging
// statements, there's no guarantee that it will stay closed
// after this call.
BASE_API void CloseLogFile();
// Async signal safe logging mechanism.
BASE_API void RawLog(int level, const char* message);
#define RAW_LOG(level, message) logging::RawLog(logging::LOG_ ## level, message)
#define RAW_CHECK(condition) \
do { \
if (!(condition)) \
logging::RawLog(logging::LOG_FATAL, "Check failed: " #condition "\n"); \
} while (0)
} // namespace logging
// These functions are provided as a convenience for logging, which is where we
// use streams (it is against Google style to use streams in other places). It
// is designed to allow you to emit non-ASCII Unicode strings to the log file,
// which is normally ASCII. It is relatively slow, so try not to use it for
// common cases. Non-ASCII characters will be converted to UTF-8 by these
// operators.
BASE_API std::ostream& operator<<(std::ostream& out, const wchar_t* wstr);
inline std::ostream& operator<<(std::ostream& out, const std::wstring& wstr) {
return out << wstr.c_str();
// The NOTIMPLEMENTED() macro annotates codepaths which have
// not been implemented yet.
// The implementation of this macro is controlled by NOTIMPLEMENTED_POLICY:
// 0 -- Do nothing (stripped by compiler)
// 1 -- Warn at compile time
// 2 -- Fail at compile time
// 3 -- Fail at runtime (DCHECK)
// 4 -- [default] LOG(ERROR) at runtime
// 5 -- LOG(ERROR) at runtime, only once per call-site
// Select default policy: LOG(ERROR)
#if defined(COMPILER_GCC)
// On Linux, with GCC, we can use __PRETTY_FUNCTION__ to get the demangled name
// of the current function in the NOTIMPLEMENTED message.
#define NOTIMPLEMENTED_MSG "Not implemented reached in " << __PRETTY_FUNCTION__
// TODO, figure out how to generate a warning
#define NOTIMPLEMENTED() do {\
static int count = 0;\
} while(0)
namespace base {
class StringPiece;
// Allows StringPiece to be logged.
BASE_API std::ostream& operator<<(std::ostream& o, const StringPiece& piece);
} // namespace base
#endif // BASE_LOGGING_H_
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