event/Call, ...: use wait() with predicate

src/input/AsyncInputStream.cxx

@@ -136,8 +136,8 @@ AsyncInputStream::Seek(std::unique_lock<Mutex> &lock,
 
 	CondInputStreamHandler cond_handler;
 	const ScopeExchangeInputStreamHandler h(*this, &cond_handler);
-	while (seek_state != SeekState::NONE)
-		cond_handler.cond.wait(lock);
+	cond_handler.cond.wait(lock,
+			       [this]{ return seek_state == SeekState::NONE; });
 
 	Check();
 }

src/input/BufferedInputStream.cxx

@@ -84,8 +84,7 @@ BufferedInputStream::Seek(std::unique_lock<Mutex> &lock,
 	seek = true;
 	wake_cond.notify_one();
 
-	while (seek)
-		client_cond.wait(lock);
+	client_cond.wait(lock, [this]{ return !seek; });
 
 	if (seek_error)
 		std::rethrow_exception(std::exchange(seek_error, {}));

src/input/Open.cxx

@@ -59,13 +59,10 @@ InputStream::OpenReady(const char *uri, Mutex &mutex)
 	{
 		std::unique_lock<Mutex> lock(mutex);
 
-		while (true) {
+		handler.cond.wait(lock, [&is]{
 			is->Update();
-			if (is->IsReady())
-				break;
-
-			handler.cond.wait(lock);
-		}
+			return is->IsReady();
+		});
 
 		is->Check();
 	}

src/input/ProxyInputStream.cxx

@@ -92,8 +92,7 @@ void
 ProxyInputStream::Seek(std::unique_lock<Mutex> &lock,
 		       offset_type new_offset)
 {
-	while (!input)
-		set_input_cond.wait(lock);
+	set_input_cond.wait(lock, [this]{ return !!input; });
 
 	input->Seek(lock, new_offset);
 	CopyAttributes();
@@ -124,8 +123,7 @@ size_t
 ProxyInputStream::Read(std::unique_lock<Mutex> &lock,
 		       void *ptr, size_t read_size)
 {
-	while (!input)
-		set_input_cond.wait(lock);
+	set_input_cond.wait(lock, [this]{ return !!input; });
 
 	size_t nbytes = input->Read(lock, ptr, read_size);
 	CopyAttributes();