Define a LoggingSettings struct to use for InitLogging()

base/logging.h

Index: base/logging.h
diff --git a/base/logging.h b/base/logging.h
index 55c9ebfafbf3db7f44419145bcb486073fff6e88..c66717420690d23202bd1f2d7f2579cfec6bcfb4 100644
--- a/base/logging.h
+++ b/base/logging.h
@@ -146,22 +146,39 @@
 
 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
-// POSIX to LOG_ONLY_TO_SYSTEM_DEBUG_LOG (aka stderr).
-enum LoggingDestination { LOG_NONE,
-                          LOG_ONLY_TO_FILE,
-                          LOG_ONLY_TO_SYSTEM_DEBUG_LOG,
-                          LOG_TO_BOTH_FILE_AND_SYSTEM_DEBUG_LOG };
+// TODO(avi): do we want to do a unification of character types here?
+#if defined(OS_WIN)
+typedef wchar_t PathChar;
+#else
+typedef char PathChar;
+#endif
+
+// Where to record logging output? A flat file and/or system debug log
+// via OutputDebugString.
+enum LoggingDestination {
+  LOG_NONE                = 0,
+  LOG_TO_FILE             = 1 << 0,
+  LOG_TO_SYSTEM_DEBUG_LOG = 1 << 1,
+
+  LOG_TO_ALL = LOG_TO_FILE | LOG_TO_SYSTEM_DEBUG_LOG,
+
+  // 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)
+  LOG_DEFAULT = LOG_TO_FILE,
+#elif defined(OS_POSIX)
+  LOG_DEFAULT = LOG_TO_SYSTEM_DEBUG_LOG,
+#endif
+};
 
 // 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.
+// Unless there is only one single-threaded process that is logging to
+// the log file, 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.
+// work properly. Defaults to 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)?
@@ -173,12 +190,19 @@ enum DcheckState {
   ENABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS
 };
 
-// TODO(avi): do we want to do a unification of character types here?
-#if defined(OS_WIN)
-typedef wchar_t PathChar;
-#else
-typedef char PathChar;
-#endif
+struct BASE_EXPORT LoggingSettings {

[brettw, 2013/06/19 18:10:13]

I think the settings here should all be explicit about what the defaults are.
One of the things about this patch is that you don't set things when the default
is OK, which means that we should guarantee in the header how such things are
done.

[akalin, 2013/06/19 19:59:18]

Done. Some of the info is in the comments for the enums, but it's probably good
to put them here anyway.

+  LoggingSettings();
+
+  LoggingDestination logging_dest;
+
+  // The three settings below have an effect only when LOG_TO_FILE is
+  // set in |logging_dest|.
+  const PathChar* log_file;
+  LogLockingState lock_log;
+  OldFileDeletionState delete_old;
+
+  DcheckState dcheck_state;
+};
 
 // 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
@@ -193,11 +217,7 @@ typedef char PathChar;
 // 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_EXPORT bool BaseInitLoggingImpl(const PathChar* log_file,
-                                     LoggingDestination logging_dest,
-                                     LogLockingState lock_log,
-                                     OldFileDeletionState delete_old,
-                                     DcheckState dcheck_state);
+BASE_EXPORT bool BaseInitLoggingImpl(const LoggingSettings& settings);
 
 // 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.
@@ -213,13 +233,8 @@ BASE_EXPORT bool BaseInitLoggingImpl(const PathChar* log_file,
 // This function may be called a second time to re-direct logging (e.g after
 // loging in to a user partition), however it should never be called more than
 // twice.
-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);
+inline bool InitLogging(const LoggingSettings& settings) {
+  return BaseInitLoggingImpl(settings);
 }
 
 // Sets the log level. Anything at or above this level will be written to the