Utility for synchronizing interface calls

os/include/os/synced_interface.h

@@ -0,0 +1,66 @@
+/*
+ * \brief  Utility for synchronizing the access of interface functions
+ * \author Norman Feske
+ * \date   2013-05-16
+ *
+ * The 'Synced_interface' utility makes the serialization of interface
+ * function calls easy. The 'Synced_interface' is a functor that takes a lock
+ * and a pointer to an interface as arguments. When called, the functor
+ * returns a smart pointer to the interface. When this smart pointer gets
+ * dereferenced, the smart pointer takes care of acquiring and releasing
+ * the lock while the interface function is executed.
+ */
+
+#ifndef _INCLUDE__OS__SYNCED_INTERFACE_H_
+#define _INCLUDE__OS__SYNCED_INTERFACE_H_
+
+/* Genode includes */
+#include <base/lock.h>
+
+namespace Genode {
+
+	template <typename IF, typename LOCK = Genode::Lock>
+	class Synced_interface
+	{
+		public:
+
+			class Guard
+			{
+				private:
+
+					LOCK &_lock;
+					IF   *_interface;
+
+					Guard(LOCK &lock, IF *interface)
+					: _lock(lock), _interface(interface)
+					{
+						_lock.lock();
+					}
+
+					friend class Synced_interface;
+
+				public:
+
+					~Guard() { _lock.unlock(); }
+
+					IF *operator -> () { return _interface; }
+			};
+
+		private:
+
+			LOCK &_lock;
+			IF   *_interface;
+
+		public:
+
+			Synced_interface(LOCK &lock, IF *interface)
+			: _lock(lock), _interface(interface) { }
+
+			Guard operator () ()
+			{
+				return Guard(_lock, _interface);
+			}
+	};
+}
+
+#endif /* _INCLUDE__OS__SYNCED_INTERFACE_H_ */

os/run/synced_interface.run

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+build "core init test/synced_interface"
+
+create_boot_directory
+
+install_config {
+	<config>
+		<parent-provides>
+			<service name="ROM"/>
+			<service name="RAM"/>
+			<service name="CPU"/>
+			<service name="RM"/>
+			<service name="CAP"/>
+			<service name="PD"/>
+			<service name="SIGNAL"/>
+			<service name="LOG"/>
+		</parent-provides>
+		<default-route>
+			<any-service> <parent/> <any-child/> </any-service>
+		</default-route>
+		<start name="test-synced_interface">
+			<resource name="RAM" quantum="1M"/>
+		</start>
+	</config>
+}
+
+build_boot_image "core init test-synced_interface"
+
+append qemu_args "-nographic -m 64"
+
+run_genode_until {child exited with exit value 0} 10
+
+grep_output {-> test-synced_interface}
+
+compare_output_to {
+[init -> test-synced_interface] lock
+[init -> test-synced_interface] adding 13 + 14
+[init -> test-synced_interface] unlock
+[init -> test-synced_interface] result is 27
+}
+

os/src/test/synced_interface/main.cc

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+/*
+ * \brief  Test for 'Synced_interface'
+ * \author Norman Feske
+ * \date   2013-05-16
+ */
+
+/*
+ * Copyright (C) 2013 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU General Public License version 2.
+ */
+
+/* Genode includes */
+#include <os/synced_interface.h>
+#include <base/printf.h>
+
+
+struct Adder
+{
+	int add(int a, int b)
+	{
+		PLOG("adding %d + %d", a, b);
+		return a + b;
+	}
+};
+
+
+struct Pseudo_lock
+{
+	void lock()   { PLOG("lock"); }
+	void unlock() { PLOG("unlock"); }
+};
+
+
+int main(int, char **)
+{
+	using namespace Genode;
+
+	Pseudo_lock lock;
+	Adder       adder;
+
+	Synced_interface<Adder, Pseudo_lock> synced_adder(lock, &adder);
+
+	int const res = synced_adder()->add(13, 14);
+
+	PLOG("result is %d", res);
+	return 0;
+}

os/src/test/synced_interface/target.mk

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+TARGET = test-synced_interface
+SRC_CC = main.cc
+LIBS   = base