// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

// Date: 2012-10-08 23:53:50

#include "butil/logging.h"

#include <gflags/gflags.h>

DEFINE_bool(log_as_json, false, "Print log as a valid JSON");

DEFINE_bool(escape_log, false, "Escape log content before printing");

#if !BRPC_WITH_GLOG

#if defined(OS_WIN)

#include <io.h>

#include <windows.h>

typedef HANDLE FileHandle;

typedef HANDLE MutexHandle;

// Windows warns on using write().  It prefers _write().

#define write(fd, buf, count) _write(fd, buf, static_cast<unsigned int>(count))

// Windows doesn't define STDERR_FILENO.  Define it here.

#define STDERR_FILENO 2

#elif defined(OS_MACOSX)

#include <mach/mach.h>

#include <mach/mach_time.h>

#include <mach-o/dyld.h>

#elif defined(OS_POSIX)

#if defined(OS_NACL) || defined(OS_LINUX)

#include <sys/time.h> // timespec doesn't seem to be in <time.h>

#else

#include <sys/syscall.h>

#endif

#include <time.h>

#endif

#if defined(OS_POSIX)

#include <errno.h>

#include <pthread.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#define MAX_PATH PATH_MAX

typedef FILE* FileHandle;

typedef pthread_mutex_t* MutexHandle;

#endif

#include <algorithm>

#include <cstring>

#include <ctime>

#include <iomanip>

#include <ostream>

#include <string>

#include "butil/file_util.h"

#include "butil/debug/alias.h"

#include "butil/debug/debugger.h"

#include "butil/debug/stack_trace.h"

#include "butil/posix/eintr_wrapper.h"

#include "butil/strings/string_util.h"

#include "butil/strings/stringprintf.h"

#include "butil/strings/utf_string_conversions.h"

#include "butil/synchronization/condition_variable.h"

#include "butil/threading/platform_thread.h"

#include "butil/threading/simple_thread.h"

#include "butil/object_pool.h"

#if defined(OS_POSIX)

#include "butil/errno.h"

#include "butil/fd_guard.h"

#endif

#if defined(OS_LINUX)

#include <fcntl.h>

#endif

#if defined(OS_ANDROID)

#include <android/log.h>

#endif

#include <map>

#include <vector>

#include <deque>

#include <limits>

#include "butil/atomicops.h"

#include "butil/thread_local.h"

#include "butil/scoped_lock.h"                        // BAIDU_SCOPED_LOCK

#include "butil/string_splitter.h"

#include "butil/time.h"

#include "butil/containers/doubly_buffered_data.h"

#include "butil/memory/singleton.h"

#include "butil/endpoint.h"

#ifdef BAIDU_INTERNAL

#include "butil/comlog_sink.h"

#endif

extern "C" {

uint64_t BAIDU_WEAK bthread_self();

typedef struct {

    uint32_t index;    // index in KeyTable

    uint32_t version;  // ABA avoidance

} bthread_key_t;

int BAIDU_WEAK bthread_key_create(bthread_key_t* key,

                                  void (*destructor)(void* data));

int BAIDU_WEAK bthread_setspecific(bthread_key_t key, void* data);

void* BAIDU_WEAK bthread_getspecific(bthread_key_t key);

}

namespace logging {

DEFINE_bool(crash_on_fatal_log, false,

            "Crash process when a FATAL log is printed");

DEFINE_bool(print_stack_on_check, true,

            "Print the stack trace when a CHECK was failed");

DEFINE_int32(v, 0, "Show all VLOG(m) messages for m <= this."

             " Overridable by --vmodule.");

DEFINE_string(vmodule, "", "per-module verbose level."

              " Argument is a comma-separated list of MODULE_NAME=LOG_LEVEL."

              " MODULE_NAME is a glob pattern, matched against the filename base"

              " (that is, name ignoring .cpp/.h)."

              " LOG_LEVEL overrides any value given by --v.");

DEFINE_bool(log_pid, false, "Log process id");

DEFINE_int32(minloglevel, 0, "Any log at or above this level will be "

             "displayed. Anything below this level will be silently ignored. "

             "0=INFO 1=NOTICE 2=WARNING 3=ERROR 4=FATAL");

DEFINE_bool(log_hostname, false, "Add host after pid in each log so"

            " that we know where logs came from when using aggregation tools"

            " like ELK.");

DEFINE_bool(log_year, false, "Log year in datetime part in each log");

DEFINE_bool(log_func_name, false, "Log function name in each log");

DEFINE_bool(async_log, false, "Use async log");

DEFINE_bool(async_log_in_background_always, false, "Async log written in background always.");

DEFINE_int32(max_async_log_queue_size, 100000, "Max async log size. "

             "If current log count of async log > max_async_log_size, "

             "Use sync log to protect process.");

DEFINE_int32(sleep_to_flush_async_log_s, 0,

             "If the value > 0, sleep before atexit to flush async log");

namespace {

LoggingDestination logging_destination = LOG_DEFAULT;

// For BLOG_ERROR and above, always print to stderr.

const int kAlwaysPrintErrorLevel = BLOG_ERROR;

// Which log file to use? This is initialized by InitLogging or

// will be lazily initialized to the default value when it is

// first needed.

#if defined(OS_WIN)

typedef std::wstring PathString;

#else

typedef std::string PathString;

#endif

PathString* log_file_name = NULL;

// this file is lazily opened and the handle may be NULL

FileHandle log_file = NULL;

// Should we pop up fatal debug messages in a dialog?

bool show_error_dialogs = false;

// An assert handler override specified by the client to be called instead of

// the debug message dialog and process termination.

LogAssertHandler log_assert_handler = NULL;

// Helper functions to wrap platform differences.

int32_t CurrentProcessId() {

#if defined(OS_WIN)

    return GetCurrentProcessId();

#elif defined(OS_POSIX)

    return getpid();

#endif

}

void DeleteFilePath(const PathString& log_name) {

#if defined(OS_WIN)

    DeleteFile(log_name.c_str());

#elif defined (OS_NACL)

    // Do nothing; unlink() isn't supported on NaCl.

#else

    unlink(log_name.c_str());

#endif

}

#if defined(OS_LINUX)

static PathString GetProcessName() {

    butil::fd_guard fd(open("/proc/self/cmdline", O_RDONLY));

    if (fd < 0) {

        return "unknown";

    }

    char buf[512];

    const ssize_t len = read(fd, buf, sizeof(buf) - 1);

    if (len <= 0) {

        return "unknown";

    }

    buf[len] = '\0';

    // Not string(buf, len) because we needs to buf to be truncated at first \0.

    // Under gdb, the first part of cmdline may include path.

    return butil::FilePath(std::string(buf)).BaseName().value();

}

#endif

PathString GetDefaultLogFile() {

#if defined(OS_WIN)

    // On Windows we use the same path as the exe.

    wchar_t module_name[MAX_PATH];

    GetModuleFileName(NULL, module_name, MAX_PATH);

    PathString log_file = module_name;

    PathString::size_type last_backslash =

        log_file.rfind('\\', log_file.size());

    if (last_backslash != PathString::npos)

        log_file.erase(last_backslash + 1);

    log_file += L"debug.log";

    return log_file;

#elif defined(OS_LINUX)

    return GetProcessName() + ".log";

#elif defined(OS_POSIX)    

    // On other platforms we just use the current directory.

    return PathString("debug.log");

#endif

}

// This class acts as a wrapper for locking the logging files.

// LoggingLock::Init() should be called from the main thread before any logging

// is done. Then whenever logging, be sure to have a local LoggingLock

// instance on the stack. This will ensure that the lock is unlocked upon

// exiting the frame.

// LoggingLocks can not be nested.

class LoggingLock {

public:

    LoggingLock() {

        LockLogging();

    }

    ~LoggingLock() {

        UnlockLogging();

    }

    static void Init(LogLockingState lock_log, const LogChar* new_log_file) {

        if (initialized)

            return;

        lock_log_file = lock_log;

        if (lock_log_file == LOCK_LOG_FILE) {

#if defined(OS_WIN)

            if (!log_mutex) {

                std::wstring safe_name;

                if (new_log_file)

                    safe_name = new_log_file;

                else

                    safe_name = GetDefaultLogFile();

                // \ is not a legal character in mutex names so we replace \ with /

                std::replace(safe_name.begin(), safe_name.end(), '\\', '/');

                std::wstring t(L"Global\\");

                t.append(safe_name);

                log_mutex = ::CreateMutex(NULL, FALSE, t.c_str());

                if (log_mutex == NULL) {

#if DEBUG

                    // Keep the error code for debugging

                    int error = GetLastError();  // NOLINT

                    butil::debug::BreakDebugger();

#endif

                    // Return nicely without putting initialized to true.

                    return;

                }

            }

#endif

        } else {

            log_lock = new butil::Mutex;

        }

        initialized = true;

    }

private:

    static void LockLogging() {

        if (lock_log_file == LOCK_LOG_FILE) {

#if defined(OS_WIN)

            ::WaitForSingleObject(log_mutex, INFINITE);

            // WaitForSingleObject could have returned WAIT_ABANDONED. We don't

            // abort the process here. UI tests might be crashy sometimes,

            // and aborting the test binary only makes the problem worse.

            // We also don't use LOG macros because that might lead to an infinite

            // loop. For more info see http://crbug.com/18028.

#elif defined(OS_POSIX)

            pthread_mutex_lock(&log_mutex);

#endif

        } else {

            // use the lock

            log_lock->lock();

        }

    }

    static void UnlockLogging() {

        if (lock_log_file == LOCK_LOG_FILE) {

#if defined(OS_WIN)

            ReleaseMutex(log_mutex);

#elif defined(OS_POSIX)

            pthread_mutex_unlock(&log_mutex);

#endif

        } else {

            log_lock->unlock();

        }

    }

    // The lock is used if log file locking is false. It helps us avoid problems

    // with multiple threads writing to the log file at the same time.

    static butil::Mutex* log_lock;

    // When we don't use a lock, we are using a global mutex. We need to do this

    // because LockFileEx is not thread safe.

#if defined(OS_WIN)

    static MutexHandle log_mutex;

#elif defined(OS_POSIX)

    static pthread_mutex_t log_mutex;

#endif

    static bool initialized;

    static LogLockingState lock_log_file;

};

// static

bool LoggingLock::initialized = false;

// static

butil::Mutex* LoggingLock::log_lock = NULL;

// static

LogLockingState LoggingLock::lock_log_file = LOCK_LOG_FILE;

#if defined(OS_WIN)

// static

MutexHandle LoggingLock::log_mutex = NULL;

#elif defined(OS_POSIX)

pthread_mutex_t LoggingLock::log_mutex = PTHREAD_MUTEX_INITIALIZER;

#endif

// Called by logging functions to ensure that debug_file is initialized

// and can be used for writing. Returns false if the file could not be

// initialized. debug_file will be NULL in this case.

bool InitializeLogFileHandle() {

    if (log_file)

        return true;

    if (!log_file_name) {

        // Nobody has called InitLogging to specify a debug log file, so here we

        // initialize the log file name to a default.

        log_file_name = new PathString(GetDefaultLogFile());

    }

    if ((logging_destination & LOG_TO_FILE) != 0) {

#if defined(OS_WIN)

        log_file = CreateFile(log_file_name->c_str(), GENERIC_WRITE,

                              FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,

                              OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

        if (log_file == INVALID_HANDLE_VALUE || log_file == NULL) {

            // try the current directory

            log_file = CreateFile(L".\\debug.log", GENERIC_WRITE,

                                  FILE_SHARE_READ | FILE_SHARE_WRITE, NULL,

                                  OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

            if (log_file == INVALID_HANDLE_VALUE || log_file == NULL) {

                log_file = NULL;

                return false;

            }

        }

        SetFilePointer(log_file, 0, 0, FILE_END);

#elif defined(OS_POSIX)

        log_file = fopen(log_file_name->c_str(), "a");

        if (log_file == NULL) {

            fprintf(stderr, "Fail to fopen %s", log_file_name->c_str());

            return false;

        }

#endif

    }

    return true;

}

void CloseFile(FileHandle log) {

#if defined(OS_WIN)

    CloseHandle(log);

#else

    fclose(log);

#endif

}

void CloseLogFileUnlocked() {

    if (!log_file)

        return;

    CloseFile(log_file);

    log_file = NULL;

}

void Log2File(const std::string& log) {

    // We can have multiple threads and/or processes, so try to prevent them

    // from clobbering each other's writes.

    // If the client app did not call InitLogging, and the lock has not

    // been created do it now. We do this on demand, but if two threads try

    // to do this at the same time, there will be a race condition to create

    // the lock. This is why InitLogging should be called from the main

    // thread at the beginning of execution.

    LoggingLock::Init(LOCK_LOG_FILE, NULL);

    LoggingLock logging_lock;

    if (InitializeLogFileHandle()) {

#if defined(OS_WIN)

        SetFilePointer(log_file, 0, 0, SEEK_END);

                DWORD num_written;

                WriteFile(log_file,

                          static_cast<const void*>(log.data()),

                          static_cast<DWORD>(log.size()),

                          &num_written,

                          NULL);

#else

        fwrite(log.data(), log.size(), 1, log_file);

        fflush(log_file);

#endif

    }

}

}  // namespace

struct BAIDU_CACHELINE_ALIGNMENT LogRequest {

    static LogRequest* const UNCONNECTED;

    LogRequest* next{NULL};

    std::string data;

};

LogRequest* const LogRequest::UNCONNECTED = (LogRequest*)(intptr_t)-1;

class AsyncLogger : public butil::SimpleThread {

public:

    static AsyncLogger* GetInstance();

    void Log(const std::string& log);

    void Log(std::string&& log);

    void StopAndJoin();

private:

friend struct DefaultSingletonTraits<AsyncLogger>;

    static LogRequest _stop_req;

    AsyncLogger();

    ~AsyncLogger() override;

    static void AtExit() {

        GetInstance()->StopAndJoin();

        if (FLAGS_sleep_to_flush_async_log_s > 0) {

            ::sleep(FLAGS_sleep_to_flush_async_log_s);

        }

    }

    void LogImpl(LogRequest* log_req);

    void Run() override;

    void LogTask(LogRequest* req);

    bool IsLogComplete(LogRequest* old_head);

    void DoLog(LogRequest* req);

    void DoLog(const std::string& log);

    butil::atomic<LogRequest*> _log_head;

    butil::Mutex _mutex;

    butil::ConditionVariable _cond;

    LogRequest* _current_log_request;

    butil::atomic<int32_t> _log_request_count;

    butil::atomic<bool> _stop;

};

AsyncLogger* AsyncLogger::GetInstance() {

    return Singleton<AsyncLogger,

                     LeakySingletonTraits<AsyncLogger>>::get();

}

AsyncLogger::AsyncLogger()

    : butil::SimpleThread("async_log_thread")

    , _log_head(NULL)

    , _cond(&_mutex)

    , _current_log_request(NULL)

    , _stop(false) {

    Start();

    // We need to stop async logger and

    // flush all async log before exit.

    atexit(AtExit);

}

AsyncLogger::~AsyncLogger() {

    StopAndJoin();

}

void AsyncLogger::Log(const std::string& log) {

    if (log.empty()) {

        return;

    }

    bool is_full = FLAGS_max_async_log_queue_size > 0 &&

        _log_request_count.fetch_add(1, butil::memory_order_relaxed) >

        FLAGS_max_async_log_queue_size;

    if (is_full || _stop.load(butil::memory_order_relaxed)) {

        // Async logger is full or stopped, fallback to sync log.

        DoLog(log);

        return;

    }

    auto log_req = butil::get_object<LogRequest>();

    if (!log_req) {

        // Async log failed, fallback to sync log.

        DoLog(log);

        return;

    }

    log_req->data = log;

    LogImpl(log_req);

}

void AsyncLogger::Log(std::string&& log) {

    if (log.empty()) {

        return;

    }

    bool is_full = FLAGS_max_async_log_queue_size > 0 &&

        _log_request_count.fetch_add(1, butil::memory_order_relaxed) >

        FLAGS_max_async_log_queue_size;

    if (is_full || _stop.load(butil::memory_order_relaxed)) {

        // Async logger is full or stopped, fallback to sync log.

        DoLog(log);

        return;

    }

    auto log_req = butil::get_object<LogRequest>();

    if (!log_req) {

        // Async log failed, fallback to sync log.

        DoLog(log);

        return;

    }

    log_req->data = std::move(log);

    LogImpl(log_req);

}

void AsyncLogger::LogImpl(LogRequest* log_req) {

    log_req->next = LogRequest::UNCONNECTED;

    // Release fence makes sure the thread getting request sees *req

    LogRequest* const prev_head =

        _log_head.exchange(log_req, butil::memory_order_release);

    if (prev_head != NULL) {

        // Someone is logging. The async_log_thread thread may spin

        // until req->next to be non-UNCONNECTED. This process is not

        // lock-free, but the duration is so short(1~2 instructions,

        // depending on compiler) that the spin rarely occurs in practice

        // (I've not seen any spin in highly contended tests).

        log_req->next = prev_head;

        return;

    }

    // We've got the right to write.

    log_req->next = NULL;

    if (!FLAGS_async_log_in_background_always) {

        // Use sync log for the LogRequest

        // which has got the right to write.

        DoLog(log_req);

        // Return when there's no more LogRequests.

        if (IsLogComplete(log_req)) {

            butil::return_object(log_req);

            return;

        }

    }

    BAIDU_SCOPED_LOCK(_mutex);

    if (_stop.load(butil::memory_order_relaxed)) {

        // Async logger is stopped, fallback to sync log.

        LogTask(log_req);

    } else {

        // Wake up async logger.

        _current_log_request = log_req;

        _cond.Signal();

    }

}

void AsyncLogger::StopAndJoin() {

    if (!_stop.exchange(true, butil::memory_order_relaxed)) {

        BAIDU_SCOPED_LOCK(_mutex);

        _cond.Signal();

    }

    if (!HasBeenJoined()) {

        Join();

    }

}

void AsyncLogger::Run() {

    while (true) {

        BAIDU_SCOPED_LOCK(_mutex);

        while (!_stop.load(butil::memory_order_relaxed) &&

               !_current_log_request) {

            _cond.Wait();

        }

        if (_stop.load(butil::memory_order_relaxed) &&

            !_current_log_request) {

            break;

        }

        LogTask(_current_log_request);

        _current_log_request = NULL;

    }

}

void AsyncLogger::LogTask(LogRequest* req) {

    do {

        // req was logged, skip it.

        if (req->next != NULL && req->data.empty()) {

            LogRequest* const saved_req = req;

            req = req->next;

            butil::return_object(saved_req);

        }

        // Log all requests to file.

        while (req->next != NULL) {

            LogRequest* const saved_req = req;

            req = req->next;

            if (!saved_req->data.empty()) {

                DoLog(saved_req);

            }

            // Release LogRequests until last request.

            butil::return_object(saved_req);

        }

        if (!req->data.empty()) {

            DoLog(req);

        }

        // Return when there's no more LogRequests.

        if (IsLogComplete(req)) {

            butil::return_object(req);

            return;

        }

    } while (true);

}

bool AsyncLogger::IsLogComplete(LogRequest* old_head) {

    if (old_head->next) {

        fprintf(stderr, "old_head->next should be NULL\n");

    }

    LogRequest* new_head = old_head;

    LogRequest* desired = NULL;

    if (_log_head.compare_exchange_strong(

        new_head, desired, butil::memory_order_acquire)) {

        // No one added new requests.

        return true;

    }

    if (new_head == old_head) {

        fprintf(stderr, "new_head should not be equal to old_head\n");

    }

    // Above acquire fence pairs release fence of exchange in Log() to make

    // sure that we see all fields of requests set.

    // Someone added new requests.

    // Reverse the list until old_head.

    LogRequest* tail = NULL;

    LogRequest* p = new_head;

    do {

        while (p->next == LogRequest::UNCONNECTED) {

            sched_yield();

        }

        LogRequest* const saved_next = p->next;

        p->next = tail;

        tail = p;

        p = saved_next;

        if (!p) {

            fprintf(stderr, "p should not be NULL\n");

        }

    } while (p != old_head);

    // Link old list with new list.

    old_head->next = tail;

    return false;

}

void AsyncLogger::DoLog(LogRequest* req) {

    DoLog(req->data);

    req->data.clear();

}

void AsyncLogger::DoLog(const std::string& log) {

    Log2File(log);

    _log_request_count.fetch_sub(1);

}

LoggingSettings::LoggingSettings()

    : logging_dest(LOG_DEFAULT),

      log_file(NULL),

      lock_log(LOCK_LOG_FILE),

      delete_old(APPEND_TO_OLD_LOG_FILE) {}

bool BaseInitLoggingImpl(const LoggingSettings& settings) {

#if defined(OS_NACL)

    // Can log only to the system debug log.

    CHECK_EQ(settings.logging_dest & ~LOG_TO_SYSTEM_DEBUG_LOG, 0);

#endif

    logging_destination = settings.logging_dest;

    // ignore file options unless logging to file is set.

    if ((logging_destination & LOG_TO_FILE) == 0)

        return true;

    LoggingLock::Init(settings.lock_log, settings.log_file);

    LoggingLock logging_lock;

    // Calling InitLogging twice or after some log call has already opened the

    // default log file will re-initialize to the new options.

    CloseLogFileUnlocked();

    if (!log_file_name)

        log_file_name = new PathString();

    if (settings.log_file) {

        *log_file_name = settings.log_file;

    } else {

        *log_file_name = GetDefaultLogFile();

    }

    if (settings.delete_old == DELETE_OLD_LOG_FILE)

        DeleteFilePath(*log_file_name);

    return InitializeLogFileHandle();

}

void SetMinLogLevel(int level) {

    FLAGS_minloglevel = std::min(BLOG_FATAL, level);

}

int GetMinLogLevel() {

    return FLAGS_minloglevel;

}

void SetShowErrorDialogs(bool enable_dialogs) {

    show_error_dialogs = enable_dialogs;

}

void SetLogAssertHandler(LogAssertHandler handler) {

    log_assert_handler = handler;

}

const char* const log_severity_names[LOG_NUM_SEVERITIES] = {

    "INFO", "NOTICE", "WARNING", "ERROR", "FATAL" };

static void PrintLogSeverity(std::ostream& os, int severity) {

    if (severity < 0) {

        // Add extra space to separate from following datetime.

        os << 'V' << -severity << ' ';

    } else if (severity < LOG_NUM_SEVERITIES) {

        os << log_severity_names[severity][0];

    } else {

        os << 'U';

    }

}

void PrintLogPrefix(std::ostream& os, int severity,

                    const char* file, int line,

                    const char* func) {

    PrintLogSeverity(os, severity);

#if defined(OS_LINUX) || defined(OS_MACOSX)

    timeval tv;

    gettimeofday(&tv, NULL);

    time_t t = tv.tv_sec;

#else

    time_t t = time(NULL);

#endif

    struct tm local_tm = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL};

#if _MSC_VER >= 1400

    localtime_s(&local_tm, &t);

#else

    localtime_r(&t, &local_tm);

#endif

    const char prev_fill = os.fill('0');

    if (FLAGS_log_year) {

        os << std::setw(4) << local_tm.tm_year + 1900;

    }

    os << std::setw(2) << local_tm.tm_mon + 1

       << std::setw(2) << local_tm.tm_mday << ' '

       << std::setw(2) << local_tm.tm_hour << ':'

       << std::setw(2) << local_tm.tm_min << ':'

       << std::setw(2) << local_tm.tm_sec;

#if defined(OS_LINUX) || defined(OS_MACOSX)

    os << '.' << std::setw(6) << tv.tv_usec;

#endif

    if (FLAGS_log_pid) {

        os << ' ' << std::setfill(' ') << std::setw(5) << CurrentProcessId();

    }

    os << ' ' << std::setfill(' ') << std::setw(5)

       << butil::PlatformThread::CurrentId() << std::setfill('0');

    if (FLAGS_log_hostname) {

        butil::StringPiece hostname(butil::my_hostname());

        if (hostname.ends_with(".baidu.com")) { // make it shorter

            hostname.remove_suffix(10);

        }

        os << ' ' << hostname;

    }

    os << ' ' << file << ':' << line;

    if (func && *func != '\0') {

        os << " " << func;

    }

    os << "] ";

    os.fill(prev_fill);

}

void PrintLogPrefix(std::ostream& os, int severity,

                    const char* file, int line) {

    PrintLogPrefix(os, severity, file, line, "");

}

static void PrintLogPrefixAsJSON(std::ostream& os, int severity,

                                 const char* file, const char* func,

                                 int line) {

    // severity

    os << "\"L\":\"";

    if (severity < 0) {

        os << 'V' << -severity;

    } else if (severity < LOG_NUM_SEVERITIES) {

        os << log_severity_names[severity][0];

    } else {

        os << 'U';

    }

    // time

    os << "\",\"T\":\"";

#if defined(OS_LINUX)

    timeval tv;

    gettimeofday(&tv, NULL);

    time_t t = tv.tv_sec;

#else

    time_t t = time(NULL);

#endif

    struct tm local_tm = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL};

#if _MSC_VER >= 1400

    localtime_s(&local_tm, &t);

#else

    localtime_r(&t, &local_tm);

#endif

    const char prev_fill = os.fill('0');

    if (FLAGS_log_year) {

        os << std::setw(4) << local_tm.tm_year + 1900;

    }

    os << std::setw(2) << local_tm.tm_mon + 1

       << std::setw(2) << local_tm.tm_mday << ' '

       << std::setw(2) << local_tm.tm_hour << ':'

       << std::setw(2) << local_tm.tm_min << ':'

       << std::setw(2) << local_tm.tm_sec;

#if defined(OS_LINUX)

    os << '.' << std::setw(6) << tv.tv_usec;

#endif

    os << "\",";

    os.fill(prev_fill);

    if (FLAGS_log_pid) {

        os << "\"pid\":\"" << CurrentProcessId() << "\",";

    }

    os << "\"tid\":\"" << butil::PlatformThread::CurrentId() << "\",";

    if (FLAGS_log_hostname) {

        butil::StringPiece hostname(butil::my_hostname());

        if (hostname.ends_with(".baidu.com")) { // make it shorter

            hostname.remove_suffix(10);

        }

        os << "\"host\":\"" << hostname << "\",";

    }

    os << "\"C\":\"" << file << ':' << line;

    if (func && *func != '\0') {

        os << " " << func;

    }

    os << "\"";

}

void EscapeJson(std::ostream& os, const butil::StringPiece& s) {

    for (auto it = s.begin(); it != s.end(); it++) {

        auto c = *it;

        switch (c) {

        case '"': os << "\\\""; break;

        case '\\': os << "\\\\"; break;

        case '\b': os << "\\b"; break;

        case '\f': os << "\\f"; break;

        case '\n': os << "\\n"; break;

        case '\r': os << "\\r"; break;

        case '\t': os << "\\t"; break;

        default: os << c;

        }

    }

}

inline void OutputLog(std::ostream& os, const butil::StringPiece& s) {

    if (FLAGS_escape_log) {

        EscapeJson(os, s);

    } else {

        os.write(s.data(), s.length());

    }

}

void PrintLog(std::ostream& os, int severity, const char* file, int line,

              const char* func, const butil::StringPiece& content) {

    if (!FLAGS_log_as_json) {

        PrintLogPrefix(os, severity, file, line, func);

        OutputLog(os, content);

    } else {

        os << '{';

        PrintLogPrefixAsJSON(os, severity, file, func, line);

        bool pair_quote = false;

        if (content.empty() || content[0] != '"') {

            // not a json, add a 'M' field

            os << ",\"M\":\"";

            pair_quote = true;

        } else {

            os << ',';

        }

        OutputLog(os, content);

        if (pair_quote) {

            os << '"';

        } else if (!content.empty() && content[content.size()-1] != '"') {

            // Controller may write `"M":"...` which misses the last quote

            os << '"';

        }

        os << '}';

    }

}

void PrintLog(std::ostream& os,

              int severity, const char* file, int line,

              const butil::StringPiece& content) {

    PrintLog(os, severity, file, line, "", content);

}

// A log message handler that gets notified of every log message we process.

class DoublyBufferedLogSink : public butil::DoublyBufferedData<LogSink*> {

public:

    DoublyBufferedLogSink() {}

    static DoublyBufferedLogSink* GetInstance();

private:

friend struct DefaultSingletonTraits<DoublyBufferedLogSink>;

    DISALLOW_COPY_AND_ASSIGN(DoublyBufferedLogSink);

};

DoublyBufferedLogSink* DoublyBufferedLogSink::GetInstance() {

    return Singleton<DoublyBufferedLogSink,

                     LeakySingletonTraits<DoublyBufferedLogSink> >::get();

}

struct SetLogSinkFn {

    LogSink* new_sink;

    LogSink* old_sink;

    bool operator()(LogSink*& ptr) {

        old_sink = ptr;

        ptr = new_sink;

        return true;

    }

};