Thread API cleanup

This patch cleans up the thread API and comes with the following
noteworthy changes:

- Introduced Cpu_session::Weight type that replaces a formerly used
  plain integer value to prevent the accidental mix-up of
  arguments.
- The enum definition of Cpu_session::DEFAULT_WEIGHT moved to
  Cpu_session::Weight::DEFAULT_WEIGHT
- New Thread constructor that takes a 'Env &' as first argument.
  The original constructors are now marked as deprecated. For the
  common use case where the default 'Weight' and 'Affinity' are
  used, a shortcut is provided. In the long term, those two
  constructors should be the only ones to remain.
- The former 'Thread<>' class template has been renamed to
  'Thread_deprecated'.
- The former 'Thread_base' class is now called 'Thread'.
- The new 'name()' accessor returns the thread's name as 'Name'
  object as centrally defined via 'Cpu_session::Name'. It is meant to
  replace the old-fashioned 'name' method that takes a buffer and size
  as arguments.
- Adaptation of the thread test to the new API

Issue #1954

repos/base/include/cpu_session/client.h

@@ -26,9 +26,9 @@ struct Genode::Cpu_session_client : Rpc_client<Cpu_session>
 	: Rpc_client<Cpu_session>(session) { }
 
 	Thread_capability
-	create_thread(Capability<Pd_session> pd, size_t quota, Name const &name,
-	              Affinity::Location affinity, addr_t utcb = 0) override {
-		return call<Rpc_create_thread>(pd, quota, name, affinity, utcb); }
+	create_thread(Capability<Pd_session> pd, Name const &name,
+	              Affinity::Location affinity, Weight weight, addr_t utcb = 0) override {
+		return call<Rpc_create_thread>(pd, name, affinity, weight, utcb); }
 
 	Ram_dataspace_capability utcb(Thread_capability thread) override {
 		return call<Rpc_utcb>(thread); }

repos/base/include/cpu_session/cpu_session.h

@@ -42,14 +42,24 @@ struct Genode::Cpu_session : Session
 
 	static const char *service_name() { return "CPU"; }
 
-	enum { THREAD_NAME_LEN = 48 };
+	enum { THREAD_NAME_LEN = 32 };
 	enum { PRIORITY_LIMIT = 1 << 16 };
 	enum { QUOTA_LIMIT_LOG2 = 15 };
 	enum { QUOTA_LIMIT = 1 << QUOTA_LIMIT_LOG2 };
 	enum { DEFAULT_PRIORITY = 0 };
-	enum { DEFAULT_WEIGHT = 10 };
 
-	typedef Rpc_in_buffer<THREAD_NAME_LEN> Name;
+	/**
+	 * Thread weight argument type for 'create_thread'
+	 */
+	struct Weight
+	{
+		enum { DEFAULT_WEIGHT = 10 };
+		size_t value = DEFAULT_WEIGHT;
+		Weight() { }
+		explicit Weight(size_t value) : value(value) { }
+	};
+
+	typedef String<THREAD_NAME_LEN> Name;
 
 	/**
 	 * Physical quota configuration
@@ -62,20 +72,20 @@ struct Genode::Cpu_session : Session
 	 * Create a new thread
 	 *
 	 * \param pd        protection domain where the thread will be executed
-	 * \param quota     CPU quota that shall be granted to the thread
 	 * \param name      name for the thread
 	 * \param affinity  CPU affinity, referring to the session-local
 	 *                  affinity space
-	 * \param utcb      Base of the UTCB that will be used by the thread
+	 * \param weight    CPU quota that shall be granted to the thread
+	 * \param utcb      base of the UTCB that will be used by the thread
 	 * \return          capability representing the new thread
 	 * \throw           Thread_creation_failed
 	 * \throw           Out_of_metadata
 	 * \throw           Quota_exceeded
 	 */
 	virtual Thread_capability create_thread(Capability<Pd_session> pd,
-	                                        size_t                 quota,
 	                                        Name const            &name,
-	                                        Affinity::Location     affinity = Affinity::Location(),
+	                                        Affinity::Location     affinity,
+	                                        Weight                 weight,
 	                                        addr_t                 utcb = 0) = 0;
 
 	/**
@@ -317,8 +327,8 @@ struct Genode::Cpu_session : Session
 
 	GENODE_RPC_THROW(Rpc_create_thread, Thread_capability, create_thread,
 	                 GENODE_TYPE_LIST(Thread_creation_failed, Out_of_metadata),
-	                 Capability<Pd_session>, size_t, Name const &,
-	                 Affinity::Location, addr_t);
+	                 Capability<Pd_session>, Name const &, Affinity::Location,
+	                 Weight, addr_t);
 	GENODE_RPC(Rpc_utcb, Ram_dataspace_capability, utcb, Thread_capability);
 	GENODE_RPC(Rpc_kill_thread, void, kill_thread, Thread_capability);
 	GENODE_RPC(Rpc_start, int, start, Thread_capability, addr_t, addr_t);