Reimplement Mutex with C++'s <mutex>

Main:
- It's now implemented thanks to `<mutex>`. No more platform-specific implementations.
- `BinaryMutex` (non-recursive) is added, as an alternative for special cases.
- Doesn't need allocation/deallocation anymore. It can live in the stack and be part of other classes.
- Because of that, it's methods are now `const` and the inner mutex is `mutable` so it can be easily used in `const` contexts.
- A no-op implementation is provided if `NO_THREADS` is defined. No more need to add `#ifdef NO_THREADS` just for this.
- `MutexLock` now takes a reference. At this point the cases of null `Mutex`es are rare. If you ever need that, just don't use `MutexLock`.
- Thread-safe utilities are therefore simpler now.

Misc.:
- `ScopedMutexLock` is dropped and replaced by `MutexLock`, because they were pretty much the same.
- Every case of lock, do-something, unlock is replaced by `MutexLock` (complex cases where it's not straightfoward are kept as as explicit lock and unlock).
- `ShaderRD` contained an `std::mutex`, which has been replaced by `Mutex`.

1 files changed, 15 insertions, 17 deletions

diff --git a/core/script_debugger_remote.cpp b/core/script_debugger_remote.cpp
index fdb6135edd..67375da6e2 100644
--- a/core/script_debugger_remote.cpp
+++ b/core/script_debugger_remote.cpp
@@ -601,7 +601,8 @@ void ScriptDebuggerRemote::debug(ScriptLanguage *p_script, bool p_can_continue,
 
 void ScriptDebuggerRemote::_get_output() {
 
-	mutex->lock();
+	MutexLock lock(mutex);
+
 	if (output_strings.size()) {
 
 		locking = true;
@@ -666,7 +667,6 @@ void ScriptDebuggerRemote::_get_output() {
 		errors.pop_front();
 		locking = false;
 	}
-	mutex->unlock();
 }
 
 void ScriptDebuggerRemote::line_poll() {
@@ -914,7 +914,8 @@ void ScriptDebuggerRemote::_send_network_bandwidth_usage() {
 
 void ScriptDebuggerRemote::send_message(const String &p_message, const Array &p_args) {
 
-	mutex->lock();
+	MutexLock lock(mutex);
+
 	if (!locking && is_peer_connected()) {
 
 		if (messages.size() >= max_messages_per_frame) {
@@ -926,7 +927,6 @@ void ScriptDebuggerRemote::send_message(const String &p_message, const Array &p_
 			messages.push_back(msg);
 		}
 	}
-	mutex->unlock();
 }
 
 void ScriptDebuggerRemote::send_error(const String &p_func, const String &p_file, int p_line, const String &p_err, const String &p_descr, ErrorHandlerType p_type, const Vector<ScriptLanguage::StackInfo> &p_stack_info) {
@@ -972,7 +972,7 @@ void ScriptDebuggerRemote::send_error(const String &p_func, const String &p_file
 		err_count++;
 	}
 
-	mutex->lock();
+	MutexLock lock(mutex);
 
 	if (!locking && is_peer_connected()) {
 
@@ -990,8 +990,6 @@ void ScriptDebuggerRemote::send_error(const String &p_func, const String &p_file
 			}
 		}
 	}
-
-	mutex->unlock();
 }
 
 void ScriptDebuggerRemote::_print_handler(void *p_this, const String &p_string, bool p_error) {
@@ -1020,19 +1018,21 @@ void ScriptDebuggerRemote::_print_handler(void *p_this, const String &p_string,
 	sdr->char_count += allowed_chars;
 	bool overflowed = sdr->char_count >= sdr->max_cps;
 
-	sdr->mutex->lock();
-	if (!sdr->locking && sdr->is_peer_connected()) {
+	{
+		MutexLock lock(sdr->mutex);
 
-		if (overflowed)
-			s += "[...]";
+		if (!sdr->locking && sdr->is_peer_connected()) {
 
-		sdr->output_strings.push_back(s);
+			if (overflowed)
+				s += "[...]";
 
-		if (overflowed) {
-			sdr->output_strings.push_back("[output overflow, print less text!]");
+			sdr->output_strings.push_back(s);
+
+			if (overflowed) {
+				sdr->output_strings.push_back("[output overflow, print less text!]");
+			}
 		}
 	}
-	sdr->mutex->unlock();
 }
 
 void ScriptDebuggerRemote::request_quit() {
@@ -1106,7 +1106,6 @@ ScriptDebuggerRemote::ScriptDebuggerRemote() :
 		last_net_bandwidth_time(0),
 		performance(Engine::get_singleton()->get_singleton_object("Performance")),
 		requested_quit(false),
-		mutex(Mutex::create()),
 		max_messages_per_frame(GLOBAL_GET("network/limits/debugger_stdout/max_messages_per_frame")),
 		n_messages_dropped(0),
 		max_errors_per_second(GLOBAL_GET("network/limits/debugger_stdout/max_errors_per_second")),
@@ -1141,5 +1140,4 @@ ScriptDebuggerRemote::~ScriptDebuggerRemote() {
 
 	remove_print_handler(&phl);
 	remove_error_handler(&eh);
-	memdelete(mutex);
 }