前言
chromium工程较大,如果看代码看不出线索。日志可以看出一些错误信息,从而找出一些线索。
chromium日志格式的定义在:Z:\chromium\src\base\logging.h
还可以自己按照chromium的日志格式,加一些自己的日志。
chrmoium默认的日志行为:
- 删掉旧的日志
- 默认日志级别:信息,警告,错误级别都开着呢
chromium日志实现
日志等级的定义
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_FATAL = 3;
const LogSeverity LOG_NUM_SEVERITIES = 4;
// LOG_DFATAL is LOG_FATAL in debug mode, ERROR in normal mode
#if defined(NDEBUG)
const LogSeverity LOG_DFATAL = LOG_ERROR;
#else
const LogSeverity LOG_DFATAL = LOG_FATAL;
#endif
设置日志记录的最小等级
logging::SetMinLogLevel(logging::LOG_VERBOSE);
日志的使用例子
由于以下宏的存在, 使用DLOG时,只能日志等级只能从INFO到DCHECK
google日志宏定义的很多,找一种能用就行。
因为FATAL 到 DCHECK 会抛异常,所以用INFO到ERROR的日志级别即可。
#define COMPACT_GOOGLE_LOG_INFO COMPACT_GOOGLE_LOG_EX_INFO(LogMessage)
#define COMPACT_GOOGLE_LOG_WARNING COMPACT_GOOGLE_LOG_EX_WARNING(LogMessage)
#define COMPACT_GOOGLE_LOG_ERROR COMPACT_GOOGLE_LOG_EX_ERROR(LogMessage)
#define COMPACT_GOOGLE_LOG_FATAL COMPACT_GOOGLE_LOG_EX_FATAL(LogMessage)
#define COMPACT_GOOGLE_LOG_DFATAL COMPACT_GOOGLE_LOG_EX_DFATAL(LogMessage)
#define COMPACT_GOOGLE_LOG_DCHECK COMPACT_GOOGLE_LOG_EX_DCHECK(LogMessage)
DLOG记录的日志前缀短些
LOG记录的日志前缀长些
// test log on every log level
DLOG(INFO) << "LOG INFO switch is on";
DLOG(WARNING) << "LOG WARNING switch is on";
DLOG(ERROR) << "LOG ERROR switch is on";
// DLOG(FATAL) << "LOG FATAL switch is on"; // 会抛异常
// DLOG(DFATAL) << "LOG DFATAL switch is on"; // 会抛异常
// DLOG(DCHECK) << "LOG DCHECK switch is on"; // 会抛异常
DLOG_IF(INFO, (2 > 1)) << "2 > 1";
DLOG_IF(WARNING, (2 >= 2)) << "2 >= 2";
DLOG_IF(ERROR, (2 > 2)) << "2 > 2";
LOG(INFO) << "LOG INFO switch is on";
// VLOG的日志级别要写全
VLOG(logging::LOG_INFO) << "find new background url request [" << str_url << "]";
日志打印出的效果
[1122/141842.138:ERROR:logging_chrome.cc(329)] LOG ERROR switch is on
[1122/141842.138:INFO:logging_chrome.cc(334)] 2 > 1
[1122/141842.138:WARNING:logging_chrome.cc(335)] 2 >= 2
[515736:518616:1122/141842.317:WARNING:url_request_job_manager.cc(55)] CreateJob url = 'https://www.gstatic.com/chrome/config/plugins_3/plugins_win.json'
[515736:518616:1122/141842.343:WARNING:url_request_job_manager.cc(55)] CreateJob url = 'https://ssl.gstatic.com/safebrowsing/csd/client_model_v5_variation_0.pb'
[515736:518616:1122/141842.344:WARNING:url_request_job_manager.cc(55)] CreateJob url = 'https://ssl.gstatic.com/safebrowsing/csd/client_model_v5_ext_variation_0.pb'
初始化日志
void ChromeMainDelegate::SandboxInitialized(const std::string& process_type) {
// Note: If you are adding a new process type below, be sure to adjust the
// AdjustLinuxOOMScore function too.
#if defined(OS_LINUX)
AdjustLinuxOOMScore(process_type);
#endif
#if defined(OS_WIN)
InitLogging(process_type);
SuppressWindowsErrorDialogs();
#endif
#if !defined(OS_ANDROID)
void InitLogging(const std::string& process_type) {
logging::OldFileDeletionState file_state =
logging::APPEND_TO_OLD_LOG_FILE;
if (process_type.empty()) {
file_state = logging::DELETE_OLD_LOG_FILE;
}
const base::CommandLine& command_line =
*base::CommandLine::ForCurrentProcess();
logging::InitChromeLogging(command_line, file_state);
}
#endif
void InitChromeLogging(const base::CommandLine& command_line,
OldFileDeletionState delete_old_log_file) {
DCHECK(!chrome_logging_initialized_) <<
"Attempted to initialize logging when it was already initialized.";
LoggingDestination logging_dest = DetermineLoggingDestination(command_line);
LogLockingState log_locking_state = LOCK_LOG_FILE;
base::FilePath log_path;
#if defined(OS_CHROMEOS)
base::FilePath target_path;
#endif
// Don't resolve the log path unless we need to. Otherwise we leave an open
// ALPC handle after sandbox lockdown on Windows.
if ((logging_dest & LOG_TO_FILE) != 0) {
log_path = GetLogFileName(command_line);
#if defined(OS_CHROMEOS)
// For BWSI (Incognito) logins, we want to put the logs in the user
// profile directory that is created for the temporary session instead
// of in the system log directory, for privacy reasons.
if (command_line.HasSwitch(chromeos::switches::kGuestSession))
log_path = GetSessionLogFile(command_line);
// On ChromeOS we log to the symlink. We force creation of a new
// symlink if we've been asked to delete the old log, since that
// indicates the start of a new session.
target_path = SetUpSymlinkIfNeeded(
log_path, delete_old_log_file == DELETE_OLD_LOG_FILE);
// Because ChromeOS manages the move to a new session by redirecting
// the link, it shouldn't remove the old file in the logging code,
// since that will remove the newly created link instead.
delete_old_log_file = APPEND_TO_OLD_LOG_FILE;
#endif // defined(OS_CHROMEOS)
} else {
log_locking_state = DONT_LOCK_LOG_FILE;
}
LoggingSettings settings;
settings.logging_dest = logging_dest;
settings.log_file = log_path.value().c_str();
settings.lock_log = log_locking_state;
settings.delete_old = delete_old_log_file;
bool success = InitLogging(settings);
#if defined(OS_CHROMEOS)
if (!success) {
DPLOG(ERROR) << "Unable to initialize logging to " << log_path.value()
<< " (which should be a link to " << target_path.value() << ")";
RemoveSymlinkAndLog(log_path, target_path);
chrome_logging_failed_ = true;
return;
}
#else // defined(OS_CHROMEOS)
if (!success) {
DPLOG(ERROR) << "Unable to initialize logging to " << log_path.value();
chrome_logging_failed_ = true;
return;
}
#endif // defined(OS_CHROMEOS)
// We call running in unattended mode "headless", and allow headless mode to
// be configured either by the Environment Variable or by the Command Line
// Switch. This is for automated test purposes.
std::unique_ptr<base::Environment> env(base::Environment::Create());
const bool is_headless = env->HasVar(env_vars::kHeadless) ||
command_line.HasSwitch(switches::kNoErrorDialogs);
// Show fatal log messages in a dialog in debug builds when not headless.
if (!is_headless)
SetShowErrorDialogs(true);
// we want process and thread IDs because we have a lot of things running
SetLogItems(true, // enable_process_id
true, // enable_thread_id
true, // enable_timestamp
false); // enable_tickcount
// Suppress system error dialogs when headless.
if (is_headless)
SuppressDialogs();
// Use a minimum log level if the command line asks for one. Ignore this
// switch if there's vlog level switch present too (as both of these switches
// refer to the same underlying log level, and the vlog level switch has
// already been processed inside InitLogging). If there is neither
// log level nor vlog level specified, then just leave the default level
// (INFO).
if (command_line.HasSwitch(switches::kLoggingLevel) &&
GetMinLogLevel() >= 0) {
std::string log_level =
command_line.GetSwitchValueASCII(switches::kLoggingLevel);
int level = 0;
if (base::StringToInt(log_level, &level) && level >= 0 &&
level < LOG_NUM_SEVERITIES) {
SetMinLogLevel(level);
} else {
DLOG(WARNING) << "Bad log level: " << log_level;
}
}
#if defined(OS_WIN)
// Enable trace control and transport through event tracing for Windows.
LogEventProvider::Initialize(kChromeTraceProviderName);
// Enable logging to the Windows Event Log.
SetEventSource(base::UTF16ToASCII(
install_static::InstallDetails::Get().install_full_name()),
BROWSER_CATEGORY, MSG_LOG_MESSAGE);
#endif
base::StatisticsRecorder::InitLogOnShutdown();
chrome_logging_initialized_ = true;
}
确定日志名称
默认的日志名称和chrome.exe同级,叫chrome_debug.log
base::FilePath GetLogFileName(const base::CommandLine& command_line) {
std::string filename = command_line.GetSwitchValueASCII(switches::kLogFile);
if (filename.empty())
base::Environment::Create()->GetVar(env_vars::kLogFileName, &filename);
if (!filename.empty())
return base::FilePath::FromUTF8Unsafe(filename);
const base::FilePath log_filename(FILE_PATH_LITERAL("chrome_debug.log"));
base::FilePath log_path;
if (base::PathService::Get(chrome::DIR_LOGS, &log_path)) {
log_path = log_path.Append(log_filename);
return log_path; // Z:\chromium\src\out\my_x86_d\chrome_debug.log
} else {
// error with path service, just use some default file somewhere
return log_filename;
}
}