player/Control: convert error from Error to std::exception_ptr

Prepare full C++ exception support in the player thread.

src/command/PlayerCommands.cxx

@@ -32,6 +32,7 @@
 #include "AudioFormat.hxx"
 #include "ReplayGainConfig.hxx"
 #include "util/ScopeExit.hxx"
+#include "util/Error.hxx"
 
 #ifdef ENABLE_DATABASE
 #include "db/update/Service.hxx"
@@ -191,10 +192,15 @@ handle_status(Client &client, gcc_unused Request args, Response &r)
 	}
 #endif
 
-	Error error = client.player_control.LockGetError();
-	if (error.IsDefined())
-		r.Format(COMMAND_STATUS_ERROR ": %s\n",
-			 error.GetMessage());
+	try {
+		client.player_control.LockCheckRethrowError();
+	} catch (const std::exception &e) {
+		r.Format(COMMAND_STATUS_ERROR ": %s\n", e.what());
+	} catch (const Error &error) {
+		r.Format(COMMAND_STATUS_ERROR ": %s\n", error.GetMessage());
+	} catch (...) {
+		r.Format(COMMAND_STATUS_ERROR ": unknown\n");
+	}
 
 	song = playlist.GetNextPosition();
 	if (song >= 0)

src/player/Control.cxx

@@ -21,6 +21,7 @@
 #include "Control.hxx"
 #include "Idle.hxx"
 #include "DetachedSong.hxx"
+#include "util/Error.hxx"
 
 #include <algorithm>
 
@@ -160,14 +161,23 @@ PlayerControl::LockGetStatus()
 	return status;
 }
 
+void
+PlayerControl::SetError(PlayerError type, std::exception_ptr &&_error)
+{
+	assert(type != PlayerError::NONE);
+	assert(_error);
+
+	error_type = type;
+	error = std::move(_error);
+}
+
 void
 PlayerControl::SetError(PlayerError type, Error &&_error)
 {
 	assert(type != PlayerError::NONE);
 	assert(_error.IsDefined());
 
-	error_type = type;
-	error = std::move(_error);
+	SetError(type, std::make_exception_ptr(std::move(_error)));
 }
 
 void
@@ -223,11 +233,11 @@ PlayerControl::SeekLocked(DetachedSong *song, SongTime t)
 	assert(next_song == nullptr);
 
 	if (error_type != PlayerError::NONE) {
-		assert(error.IsDefined());
-		throw error;
+		assert(error);
+		std::rethrow_exception(error);
 	}
 
-	assert(!error.IsDefined());
+	assert(!error);
 }
 
 void

src/player/Control.hxx

@@ -24,12 +24,14 @@
 #include "thread/Mutex.hxx"
 #include "thread/Cond.hxx"
 #include "thread/Thread.hxx"
-#include "util/Error.hxx"
 #include "CrossFade.hxx"
 #include "Chrono.hxx"
 
+#include <exception>
+
 #include <stdint.h>
 
+class Error;
 class PlayerListener;
 class MultipleOutputs;
 class DetachedSong;
@@ -135,7 +137,7 @@ struct PlayerControl {
 	 * #PlayerError::NONE.  The object must be freed when this
 	 * object transitions back to #PlayerError::NONE.
 	 */
-	Error error;
+	std::exception_ptr error;
 
 	/**
 	 * A copy of the current #DetachedSong after its tags have
@@ -327,7 +329,7 @@ private:
 
 	void ClearError() {
 		error_type = PlayerError::NONE;
-		error.Clear();
+		error = std::exception_ptr();
 	}
 
 public:
@@ -356,28 +358,25 @@ public:
 	 * @param error detailed error information; must be defined.
 	 */
 	void SetError(PlayerError type, Error &&error);
+	void SetError(PlayerError type, std::exception_ptr &&_error);
 
 	/**
-	 * Checks whether an error has occurred, and if so, returns a
-	 * copy of the #Error object.
+	 * Checks whether an error has occurred, and if so, rethrows
+	 * it.
 	 *
 	 * Caller must lock the object.
 	 */
-	gcc_pure
-	Error GetError() const {
-		Error result;
+	void CheckRethrowError() const {
 		if (error_type != PlayerError::NONE)
-			result.Set(error);
-		return result;
+			std::rethrow_exception(error);
 	}
 
 	/**
-	 * Like GetError(), but locks and unlocks the object.
+	 * Like CheckRethrowError(), but locks and unlocks the object.
 	 */
-	gcc_pure
-	Error LockGetError() const {
+	void LockCheckRethrowError() const {
 		const ScopeLock protect(mutex);
-		return GetError();
+		CheckRethrowError();
 	}
 
 	void LockClearError();