Lock all access to logging data, in case it's reinitialized

base/logging.cc

 // Copyright (c) 2010 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.
 
 #include "base/logging.h"
 
 #if defined(OS_WIN)
 #include <io.h>
 #include <windows.h>
 typedef HANDLE FileHandle;
@@ skipping 42 matching lines @@
 #include "base/utf_string_conversions.h"
 
 namespace logging {
 
 bool g_enable_dcheck = false;
 
 const char* const log_severity_names[LOG_NUM_SEVERITIES] = {
   "INFO", "WARNING", "ERROR", "ERROR_REPORT", "FATAL" };
 
 int min_log_level = 0;
-LogLockingState lock_log_file = LOCK_LOG_FILE;
 
 // The default set here for logging_destination will only be used if
 // InitLogging is not called.  On Windows, use a file next to the exe;
 // on POSIX platforms, where it may not even be possible to locate the
 // executable on disk, use stderr.
 #if defined(OS_WIN)
 LoggingDestination logging_destination = LOG_ONLY_TO_FILE;
 #elif defined(OS_POSIX)
 LoggingDestination logging_destination = LOG_ONLY_TO_SYSTEM_DEBUG_LOG;
 #endif
@@ skipping 28 matching lines @@
 
 // An assert handler override specified by the client to be called instead of
 // the debug message dialog and process termination.
 LogAssertHandlerFunction log_assert_handler = NULL;
 // An report handler override specified by the client to be called instead of
 // the debug message dialog.
 LogReportHandlerFunction log_report_handler = NULL;
 // A log message handler that gets notified of every log message we process.
 LogMessageHandlerFunction log_message_handler = NULL;
 
-// 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.  Use
-// LockImpl directly instead of using Lock, because Lock makes logging calls.
-static LockImpl* log_lock = NULL;
-
-// 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)
-MutexHandle log_mutex = NULL;
-#elif defined(OS_POSIX)
-pthread_mutex_t log_mutex = PTHREAD_MUTEX_INITIALIZER;
-#endif
-
 // Helper functions to wrap platform differences.
 
 int32 CurrentProcessId() {
 #if defined(OS_WIN)
   return GetCurrentProcessId();
 #elif defined(OS_POSIX)
   return getpid();
 #endif
 }
 
@@ skipping 36 matching lines @@
 }
 
 void DeleteFilePath(const PathString& log_name) {
 #if defined(OS_WIN)
   DeleteFile(log_name.c_str());
 #else
   unlink(log_name.c_str());
 #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) {
+    if (initialized)
+      return;
+    lock_log_file = lock_log;
+    if (lock_log_file == LOCK_LOG_FILE) {
+#if defined(OS_WIN)
+      if (!log_mutex) {
+        // \ is not a legal character in mutex names so we replace \ with /
+        std::wstring safe_name(*log_file_name);
+        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());
+      }
+#endif
+    } else {
+      log_lock = new LockImpl();
+    }
+    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.  Use
+  // LockImpl directly instead of using Lock, because Lock makes logging calls.
+  static LockImpl* 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
+LockImpl* 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.
@@ skipping 33 matching lines @@
 #elif defined(OS_POSIX)
     log_file = fopen(log_file_name->c_str(), "a");
     if (log_file == NULL)
       return false;
 #endif
   }
 
   return true;
 }
 
-void InitLogMutex() {
-#if defined(OS_WIN)
-  if (!log_mutex) {
-    // \ is not a legal character in mutex names so we replace \ with /
-    std::wstring safe_name(*log_file_name);
-    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());
-  }
-#elif defined(OS_POSIX)
-  // statically initialized
-#endif
-}
-
 void BaseInitLoggingImpl(const PathChar* new_log_file,
                          LoggingDestination logging_dest,
                          LogLockingState lock_log,
                          OldFileDeletionState delete_old) {
   g_enable_dcheck =
       CommandLine::ForCurrentProcess()->HasSwitch(switches::kEnableDCHECK);
 
+  LoggingLock::Init(lock_log);
+
+  LoggingLock logging_lock;
+
   if (log_file) {
     // calling InitLogging twice or after some log call has already opened the
     // default log file will re-initialize to the new options
     CloseFile(log_file);
     log_file = NULL;
   }
 
-  lock_log_file = lock_log;
   logging_destination = logging_dest;
 
   // ignore file options if logging is disabled or only to system
   if (logging_destination == LOG_NONE ||
       logging_destination == LOG_ONLY_TO_SYSTEM_DEBUG_LOG)
     return;
 
   if (!log_file_name)
     log_file_name = new PathString();
   *log_file_name = new_log_file;
   if (delete_old == DELETE_OLD_LOG_FILE)
     DeleteFilePath(*log_file_name);
 
-  if (lock_log_file == LOCK_LOG_FILE) {
-    InitLogMutex();
-  } else if (!log_lock) {
-    log_lock = new LockImpl();
-  }
+  InitializeLogFileHandle();
 
-  InitializeLogFileHandle();
 }
 
 void SetMinLogLevel(int level) {
   min_log_level = level;
 }
 
 int GetMinLogLevel() {
   return min_log_level;
 }
 
@@ skipping 216 matching lines @@
       fflush(stderr);
     }
   } else if (severity_ >= kAlwaysPrintErrorLevel) {
     // When we're only outputting to a log file, above a certain log level, we
     // should still output to stderr so that we can better detect and diagnose
     // problems with unit tests, especially on the buildbots.
     fprintf(stderr, "%s", str_newline.c_str());
     fflush(stderr);
   }
 
+  // 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);
   // write to log file
   if (logging_destination != LOG_NONE &&
-      logging_destination != LOG_ONLY_TO_SYSTEM_DEBUG_LOG &&
-      InitializeLogFileHandle()) {
-    // We can have multiple threads and/or processes, so try to prevent them
-    // from clobbering each other's writes.
-    if (lock_log_file == LOCK_LOG_FILE) {
-      // Ensure that the mutex is initialized in case the client app did not
-      // call InitLogging. This is not thread safe. See below.
-      InitLogMutex();
-
+      logging_destination != LOG_ONLY_TO_SYSTEM_DEBUG_LOG) {
+    LoggingLock logging_lock;
+    if (InitializeLogFileHandle()) {
 #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);
+      SetFilePointer(log_file, 0, 0, SEEK_END);
+      DWORD num_written;
+      WriteFile(log_file,
+                static_cast<const void*>(str_newline.c_str()),
+                static_cast<DWORD>(str_newline.length()),
+                &num_written,
+                NULL);
+#else
+      fprintf(log_file, "%s", str_newline.c_str());
+      fflush(log_file);
 #endif
-    } else {
-      // use the lock
-      if (!log_lock) {
-        // The client app did not call InitLogging, and so the lock has not
-        // been created. 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.
-        log_lock = new LockImpl();
-      }
-      log_lock->Lock();
-    }
-
-#if defined(OS_WIN)
-    SetFilePointer(log_file, 0, 0, SEEK_END);
-    DWORD num_written;
-    WriteFile(log_file,
-              static_cast<const void*>(str_newline.c_str()),
-              static_cast<DWORD>(str_newline.length()),
-              &num_written,
-              NULL);
-#else
-    fprintf(log_file, "%s", str_newline.c_str());
-    fflush(log_file);
-#endif
-
-    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();
     }
   }
 
   if (severity_ == LOG_FATAL) {
     // display a message or break into the debugger on a fatal error
     if (DebugUtil::BeingDebugged()) {
       DebugUtil::BreakDebugger();
     } else {
       if (log_assert_handler) {
         // make a copy of the string for the handler out of paranoia
@@ skipping 103 matching lines @@
     : err_(err),
       log_message_(file, line, severity) {
 }
 
 ErrnoLogMessage::~ErrnoLogMessage() {
   stream() << ": " << safe_strerror(err_);
 }
 #endif  // OS_WIN
 
 void CloseLogFile() {
+  LoggingLock logging_lock;
+
   if (!log_file)
     return;
 
   CloseFile(log_file);
   log_file = NULL;
 }
 
 void RawLog(int level, const char* message) {
   if (level >= min_log_level) {
     size_t bytes_written = 0;
@@ skipping 23 matching lines @@
 
   if (level == LOG_FATAL)
     DebugUtil::BreakDebugger();
 }
 
 }  // namespace logging
 
 std::ostream& operator<<(std::ostream& out, const wchar_t* wstr) {
   return out << WideToUTF8(std::wstring(wstr));
 }