Extract logging logic

Previously logging logic was scattered over OS class implementations
with plenty of duplication. Major changes in this commit:

 - Extracted logging logic into a separate Logger hierarchy. It allows
   easy configuration of logging mechanism depending on compile-time or
   run-time configuration.

 - Implemented RotatedFileLogger which is usually used with StdLogger,
   providing persistency of logs. It is often important to be able to
   obtain logs of the game even in production to be able to understand
   what happened prior to some problem. On mobile there previously was
   no way to obtain the logs aside from having the device connected to
   your machine.

 - flush() is not performed in release mode for every logged line. It
   is only performed for errors.

1 files changed, 18 insertions, 14 deletions

diff --git a/platform/android/os_android.cpp b/platform/android/os_android.cpp
index dbea2d7531..0eb14f6af3 100644
--- a/platform/android/os_android.cpp
+++ b/platform/android/os_android.cpp
@@ -47,6 +47,15 @@
 #include "file_access_jandroid.h"
 #endif
 
+class AndroidLogger : public Logger {
+public:
+	virtual void logv(const char *p_format, va_list p_list, bool p_err) {
+		__android_log_vprint(p_err ? ANDROID_LOG_ERROR : ANDROID_LOG_INFO, "godot", p_format, p_list);
+	}
+
+	virtual ~AndroidLogger() {}
+};
+
 int OS_Android::get_video_driver_count() const {
 
 	return 1;
@@ -111,6 +120,13 @@ void OS_Android::initialize_core() {
 #endif
 }
 
+void OS_Android::initialize_logger() {
+	Vector<Logger *> loggers;
+	loggers.push_back(memnew(AndroidLogger));
+	loggers.push_back(memnew(RotatedFileLogger("user://logs/log.txt")));
+	_set_logger(memnew(CompositeLogger(loggers)));
+}
+
 void OS_Android::set_opengl_extensions(const char *p_gl_extensions) {
 
 	ERR_FAIL_COND(!p_gl_extensions);
@@ -162,23 +178,9 @@ void OS_Android::delete_main_loop() {
 }
 
 void OS_Android::finalize() {
-
 	memdelete(input);
 }
 
-void OS_Android::vprint(const char *p_format, va_list p_list, bool p_stderr) {
-
-	__android_log_vprint(p_stderr ? ANDROID_LOG_ERROR : ANDROID_LOG_INFO, "godot", p_format, p_list);
-}
-
-void OS_Android::print(const char *p_format, ...) {
-
-	va_list argp;
-	va_start(argp, p_format);
-	__android_log_vprint(ANDROID_LOG_INFO, "godot", p_format, argp);
-	va_end(argp);
-}
-
 void OS_Android::alert(const String &p_alert, const String &p_title) {
 
 	//print("ALERT: %s\n", p_alert.utf8().get_data());
@@ -737,6 +739,8 @@ OS_Android::OS_Android(GFXInitFunc p_gfx_init_func, void *p_gfx_init_ud, OpenURI
 	set_keep_screen_on_func = p_set_keep_screen_on_func;
 	alert_func = p_alert_func;
 	use_reload_hooks = false;
+
+	_set_logger(memnew(AndroidLogger));
 }
 
 OS_Android::~OS_Android() {