diff --git a/cmake/asyncpp-options.cmake b/cmake/asyncpp-options.cmake
index 0eb8548..5e406d4 100644
--- a/cmake/asyncpp-options.cmake
+++ b/cmake/asyncpp-options.cmake
@@ -9,3 +9,6 @@ Option                              ( ASYNCPP_INSTALL_PACKAGE
 Option                              ( ASYNCPP_USE_GIT_VERSION
                                       "Read the git tags to get the version of asyncpp"
                                       ON )
+Option                              ( ASYNCPP_FEATURE_TIMING_ENABLED
+                                      "Enable the timing features of asyncpp"
+                                      ON )
diff --git a/cmake/config.h.in b/cmake/config.h.in
new file mode 100644
index 0000000..85fe7b8
--- /dev/null
+++ b/cmake/config.h.in
@@ -0,0 +1,3 @@
+#pragma once
+
+#cmakedefine ASYNCPP_FEATURE_TIMING_ENABLED
diff --git a/include/asyncpp.h b/include/asyncpp.h
index 7e5f792..3e57fa6 100644
--- a/include/asyncpp.h
+++ b/include/asyncpp.h
@@ -1,3 +1,9 @@
 #pragma once
 
+#include <asyncpp/config.h>
+
 #include <asyncpp/core.h>
+
+#ifdef ASYNCPP_FEATURE_TIMING_ENABLED
+    #include <asyncpp/timing.h>
+#endif
diff --git a/include/asyncpp/core/future.h b/include/asyncpp/core/future.h
index 13b1ae8..706ef96 100644
--- a/include/asyncpp/core/future.h
+++ b/include/asyncpp/core/future.h
@@ -6,6 +6,6 @@
 #include "future/lazy.inl"
 #include "future/and_then.inl"
 
-#ifdef asyncpp_timing
+#ifdef ASYNCPP_FEATURE_TIMING_ENABLED
 #include "future/timeout.inl"
 #endif
diff --git a/include/asyncpp/core/future/future.h b/include/asyncpp/core/future/future.h
index 2862d39..18ca90c 100644
--- a/include/asyncpp/core/future/future.h
+++ b/include/asyncpp/core/future/future.h
@@ -57,7 +57,7 @@ namespace asyncpp
             typename X_lambda>
         inline auto and_then(X_lambda&& p_lambda) &&;
 
-    #ifdef asyncpp_timing
+    #ifdef ASYNCPP_FEATURE_TIMING_ENABLED
     public:
         /**
          * @brief Throw an execption if the timeout has passed.
diff --git a/include/asyncpp/core/future/timeout.inl b/include/asyncpp/core/future/timeout.inl
index d9a72ad..5985fda 100644
--- a/include/asyncpp/core/future/timeout.inl
+++ b/include/asyncpp/core/future/timeout.inl
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <asyncpp/timing/timeout/timeout_future.h>
+
 #include "future.h"
 
 namespace asyncpp {
@@ -22,11 +24,11 @@ namespace __future {
                                         derived_type const &,
                                         derived_type &>;
         using derived_forward_type  = forward_type_t<X_mode, derived_ref_type>;
-        using timeout_type          = asyncpp::timing::timeout<derived_storage_type>;
+        using timeout_future_type   = asyncpp::timing::timeout_future<derived_storage_type>;
 
         auto& self = static_cast<derived_ref_type>(p_self);
 
-        return timeout_type(
+        return timeout_future_type(
             std::forward<derived_forward_type>(self),
             p_timeout);
     }
diff --git a/include/asyncpp/core/stream.h b/include/asyncpp/core/stream.h
index f70b0c4..e120ad9 100644
--- a/include/asyncpp/core/stream.h
+++ b/include/asyncpp/core/stream.h
@@ -6,6 +6,6 @@
 #include "stream/flatten.inl"
 #include "stream/for_each.inl"
 
-#ifdef asyncpp_timing
+#ifdef ASYNCPP_FEATURE_TIMING_ENABLED
 #include "stream/timeout.inl"
 #endif
diff --git a/include/asyncpp/core/stream/stream.h b/include/asyncpp/core/stream/stream.h
index 038e98d..9b13b62 100644
--- a/include/asyncpp/core/stream/stream.h
+++ b/include/asyncpp/core/stream/stream.h
@@ -75,7 +75,7 @@ namespace asyncpp
             chaining_mode X_mode = move>
         inline auto flatten() &&;
 
-    #ifdef asyncpp_timing
+    #ifdef ASYNCPP_FEATURE_TIMING_ENABLED
     public:
         /**
          * @brief Throw an execption if the timeout has passed.
diff --git a/include/asyncpp/core/stream/timeout.inl b/include/asyncpp/core/stream/timeout.inl
index 8b9159f..7eda9d1 100644
--- a/include/asyncpp/core/stream/timeout.inl
+++ b/include/asyncpp/core/stream/timeout.inl
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <asyncpp/timing/timeout/timeout_stream.h>
+
 #include "stream.h"
 
 namespace asyncpp {
@@ -22,11 +24,11 @@ namespace __stream {
                                         derived_type const &,
                                         derived_type &>;
         using derived_forward_type  = forward_type_t<X_mode, derived_ref_type>;
-        using timeout_type          = timing::timeout<derived_storage_type>;
+        using timeout_stream_type   = timing::timeout_stream<derived_storage_type>;
 
         auto& self = static_cast<derived_ref_type>(p_self);
 
-        return timeout_type(
+        return timeout_stream_type(
             std::forward<derived_forward_type>(self),
             p_timeout);
     }
diff --git a/include/asyncpp/core/task/task.h b/include/asyncpp/core/task/task.h
index a7f16fc..f7b01a8 100644
--- a/include/asyncpp/core/task/task.h
+++ b/include/asyncpp/core/task/task.h
@@ -59,6 +59,9 @@ namespace asyncpp
              */
             inline lock(task::handle_ptr_s p_handle);
 
+            inline lock(lock &&) = delete;
+            inline lock(lock const &) = delete;
+
             /**
              * @brief Destructor.
              */
diff --git a/include/asyncpp/core/task/task.inl b/include/asyncpp/core/task/task.inl
index 3043d09..665f1f7 100644
--- a/include/asyncpp/core/task/task.inl
+++ b/include/asyncpp/core/task/task.inl
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <cppcore/misc/exception.h>
+
 #include "task.h"
 
 namespace asyncpp
@@ -8,7 +10,12 @@ namespace asyncpp
     /* task::lock */
 
     task::lock::lock(task::handle_ptr_s p_handle)
-        { local_storage().current = p_handle; }
+    {
+        auto& current = local_storage().current;
+        if (!current.expired())
+            throw cppcore::invalid_operation_exception("Current task is already assigned!");
+        current = p_handle;
+    }
 
     task::lock::~lock()
         { local_storage().current.reset(); }
diff --git a/include/asyncpp/executor/executor.inl b/include/asyncpp/executor/executor.inl
index d2ac892..720c466 100644
--- a/include/asyncpp/executor/executor.inl
+++ b/include/asyncpp/executor/executor.inl
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <cppcore/misc/exception.h>
+
 #include "executor.h"
 
 #include "task_handle.inl"
@@ -33,7 +35,12 @@ namespace executor {
     /* lock */
 
     executor::lock::lock(executor& p_current)
-        { executor::local_storage().current = &p_current; }
+    {
+        auto& current = executor::local_storage().current;
+        if (current)
+            throw cppcore::invalid_operation_exception("Current executor is already assigned!");
+        current = &p_current;
+    }
 
     executor::lock::~lock()
         { executor::local_storage().current = nullptr; }
diff --git a/include/asyncpp/timing.h b/include/asyncpp/timing.h
index 47708b7..7472958 100644
--- a/include/asyncpp/timing.h
+++ b/include/asyncpp/timing.h
@@ -1,13 +1,8 @@
 #pragma once
 
-#define asyncpp_timing
+#define ASYNCPP_FEATURE_TIMING_ENABLED
 
 #include "timing/delay.h"
 #include "timing/interval.h"
 #include "timing/timeout.h"
 #include "timing/timer.h"
-
-#include "timing/delay.inl"
-#include "timing/interval.inl"
-#include "timing/timeout.inl"
-#include "timing/timer.inl"
diff --git a/include/asyncpp/timing/delay.h b/include/asyncpp/timing/delay.h
index 83609d2..b3dab2f 100644
--- a/include/asyncpp/timing/delay.h
+++ b/include/asyncpp/timing/delay.h
@@ -1,64 +1,5 @@
 #pragma once
 
-#include <asyncpp/core/misc.h>
-#include <asyncpp/core/future/future.h>
+#include "delay/delay.h"
 
-#include "timer.h"
-#include "delay.pre.h"
-
-namespace asyncpp {
-namespace timing {
-
-    struct delay final
-        : public base_future<void, delay>
-    {
-    public:
-        using value_type        = void;
-        using base_future_type  = base_future<void, delay>;
-        using result_type       = typename base_future_type::result_type;
-
-    private:
-        time_point                  _deadline;
-        __impl::registration_ptr_w  _registration;
-
-    public:
-        /**
-         * @brief Constructor. Create a delay at the given deadline.
-         */
-        inline delay(const time_point& p_deadline);
-
-        /**
-         * @brief Constructor. Create a delay with the given duration.
-         */
-        template<typename T_base, typename T_ratio>
-        inline delay(const duration<T_base, T_ratio>& p_duration);
-
-        /**
-         * @brief Destructor.
-         */
-        inline ~delay();
-
-        /**
-         * @brief Get the current deadline of the delay.
-         */
-        inline time_point deadline() const;
-
-        /**
-         * @brief Reset the delay to a new time point.
-         */
-        inline void reset(const time_point& p_deadline);
-
-        /**
-         * @brief Reset the delay to the given duration.
-         */
-        template<typename T_base, typename T_ratio>
-        inline void reset(const duration<T_base, T_ratio>& p_duration);
-
-    public: /* future */
-        /**
-         * @brief Poll the result from the future.
-         */
-        inline result_type poll();
-    };
-
-} }
+#include "delay/delay.inl"
diff --git a/include/asyncpp/timing/delay/delay.h b/include/asyncpp/timing/delay/delay.h
new file mode 100644
index 0000000..bac3e09
--- /dev/null
+++ b/include/asyncpp/timing/delay/delay.h
@@ -0,0 +1,65 @@
+#pragma once
+
+#include <asyncpp/core/misc.h>
+#include <asyncpp/core/future/future.h>
+
+#include "delay.pre.h"
+#include "../timer/timer.h"
+#include "../timer/resource.h"
+
+namespace asyncpp {
+namespace timing {
+
+    struct delay final
+        : public base_future<void, delay>
+    {
+    public:
+        using value_type        = void;
+        using base_future_type  = base_future<void, delay>;
+        using result_type       = typename base_future_type::result_type;
+
+    private:
+        time_point              _deadline;
+        __impl::resource_ptr_w  _resource;
+
+    public:
+        /**
+         * @brief Constructor. Create a delay at the given deadline.
+         */
+        inline delay(const time_point& p_deadline);
+
+        /**
+         * @brief Constructor. Create a delay with the given duration.
+         */
+        template<typename T_base, typename T_ratio>
+        inline delay(const duration<T_base, T_ratio>& p_duration);
+
+        /**
+         * @brief Destructor.
+         */
+        inline ~delay();
+
+        /**
+         * @brief Get the current deadline of the delay.
+         */
+        inline time_point deadline() const;
+
+        /**
+         * @brief Reset the delay to a new time point.
+         */
+        inline void reset(const time_point& p_deadline);
+
+        /**
+         * @brief Reset the delay to the given duration.
+         */
+        template<typename T_base, typename T_ratio>
+        inline void reset(const duration<T_base, T_ratio>& p_duration);
+
+    public: /* future */
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
+    };
+
+} }
diff --git a/include/asyncpp/timing/delay.inl b/include/asyncpp/timing/delay/delay.inl
similarity index 66%
rename from include/asyncpp/timing/delay.inl
rename to include/asyncpp/timing/delay/delay.inl
index 3ead3de..ace33a6 100644
--- a/include/asyncpp/timing/delay.inl
+++ b/include/asyncpp/timing/delay/delay.inl
@@ -5,7 +5,7 @@
 
 #include "delay.h"
 
-#include "timer.inl"
+#include "../timer/timer_base.inl"
 
 namespace asyncpp {
 namespace timing {
@@ -13,32 +13,32 @@ namespace timing {
     /* delay */
 
     delay::delay(const time_point& p_deadline)
-        : _deadline     (p_deadline)
-        , _registration ()
+        : _deadline (p_deadline)
+        , _resource ()
         { }
 
     template<typename T_base, typename T_ratio>
     delay::delay(const duration<T_base, T_ratio>& p_duration)
-        : _deadline     (asyncpp::now() + p_duration)
-        , _registration ()
+        : _deadline (asyncpp::now() + p_duration)
+        , _resource ()
         { }
 
     inline delay::~delay()
-        { __impl::timer_base::unregister_resource(_registration); }
+        { __impl::timer_base::unregister_resource(_resource); }
 
     time_point delay::deadline() const
         { return _deadline; }
 
     void delay::reset(const time_point& p_deadline)
     {
-        __impl::timer_base::unregister_resource(_registration);
+        __impl::timer_base::unregister_resource(_resource);
         _deadline = p_deadline;
     }
 
     template<typename T_base, typename T_ratio>
     void delay::reset(const duration<T_base, T_ratio>& p_duration)
     {
-        __impl::timer_base::unregister_resource(_registration);
+        __impl::timer_base::unregister_resource(_resource);
         _deadline = asyncpp::now() + p_duration;
     }
 
@@ -51,8 +51,8 @@ namespace timing {
         if (_deadline <= now)
             return result_type::ready();
 
-        if (_registration.expired())
-            _registration = timing::__impl::timer_base::register_resource(_deadline);
+        if (_resource.expired())
+            _resource = timing::__impl::timer_base::register_resource(_deadline);
 
         return result_type::not_ready();
     }
diff --git a/include/asyncpp/timing/delay.pre.h b/include/asyncpp/timing/delay/delay.pre.h
similarity index 100%
rename from include/asyncpp/timing/delay.pre.h
rename to include/asyncpp/timing/delay/delay.pre.h
diff --git a/include/asyncpp/timing/impl/timer_base.h b/include/asyncpp/timing/impl/timer_base.h
deleted file mode 100644
index e29fc42..0000000
--- a/include/asyncpp/timing/impl/timer_base.h
+++ /dev/null
@@ -1,88 +0,0 @@
-#pragma once
-
-#include <set>
-#include <memory>
-
-#include <cppcore/synchronization/locked.h>
-
-#include <asyncpp/core/misc.h>
-
-#include "timer_base.pre.h"
-#include "registration.h"
-
-namespace asyncpp {
-namespace timing {
-namespace __impl {
-
-    struct timer_base
-    {
-    private:
-        struct registration_less_compare
-        {
-            constexpr bool operator()(
-                const registration_ptr_s& lhs,
-                const registration_ptr_s& rhs) const;
-        };
-
-        using registration_set = std::set<registration_ptr_s, registration_less_compare>;
-
-    protected:
-        cppcore::locked<registration_set> _registrations;
-
-    public:
-        /**
-         * @brief Constructor.
-         */
-        inline ~timer_base();
-
-    public:
-        /**
-         * @brief Get the number of resources assigned to this timer_base.
-         */
-        inline size_t resource_count() const;
-
-        /**
-         * @brief Set the thread local current timer_base.
-         */
-        inline void make_current();
-
-        /**
-         * @brief Set the thread local current timer_base.
-         */
-        inline void clear_current();
-
-    public:
-        /**
-         * @brief Get the thread local timer_base instance.
-         */
-        static inline timer_base* current();
-
-        /**
-         * @brief Register a new resource within this timer_base.
-         */
-        static inline registration_ptr_w register_resource(const time_point& p_deadline);
-
-        /**
-         * @brief Register a new resource within this timer_base.
-         */
-        static inline void unregister_resource(registration_ptr_w& p_value);
-
-    private:
-        /**
-         * @brief Create registration for a new resource.
-         */
-        registration_ptr_w create_registration(const time_point& p_deadline);
-
-    protected:
-        struct storage
-        {
-            timer_base* current { nullptr };
-        };
-
-        /**
-         * @brief Get the thread local storage.
-         */
-        static inline storage& local_storage();
-    };
-
-} } }
diff --git a/include/asyncpp/timing/impl/timer_base.inl b/include/asyncpp/timing/impl/timer_base.inl
deleted file mode 100644
index 7d31710..0000000
--- a/include/asyncpp/timing/impl/timer_base.inl
+++ /dev/null
@@ -1,91 +0,0 @@
-#pragma once
-
-#include "timer_base.h"
-
-namespace asyncpp {
-namespace timing {
-namespace __impl {
-
-    /* timer_base::inner_less_compare */
-
-    constexpr bool timer_base::registration_less_compare::operator()(
-        const registration_ptr_s& lhs,
-        const registration_ptr_s& rhs) const
-    {
-        return  (lhs->deadline <  rhs->deadline)
-                    ?  true
-                    :
-                (lhs->deadline == rhs->deadline)
-            &&  (lhs.get()     <  rhs.get())
-                    ?   true
-                    :   false;
-    }
-
-    /* timer_base */
-
-    timer_base::~timer_base()
-    {
-        auto& s = local_storage();
-        if (s.current == this)
-            s.current = nullptr;
-    }
-
-    size_t timer_base::resource_count() const
-        { return _registrations.lock()->size(); }
-
-    void timer_base::make_current()
-    {
-        auto& s = local_storage();
-        if (s.current)
-            throw std::runtime_error("Thread local timer_base instance is already assigned!");
-        s.current = this;
-    }
-
-    void timer_base::clear_current()
-    {
-        auto& s = local_storage();
-        if (s.current && s.current != this)
-            throw std::runtime_error("Thread local timer_base instance is not assigned to this instance!");
-        s.current = nullptr;
-    }
-
-    timer_base* timer_base::current()
-        { return local_storage().current; }
-
-    registration_ptr_w timer_base::register_resource(const time_point& p_deadline)
-    {
-        auto t = current();
-
-        if (!t)
-            throw std::runtime_error("Thread local timer_base instance is not assigned!");
-
-        return t->create_registration(p_deadline);
-    }
-
-    registration_ptr_w timer_base::create_registration(const time_point& p_deadline)
-    {
-        auto r = std::make_shared<registration>(
-            *this,
-            p_deadline,
-            task::current());
-
-        _registrations.lock()->insert(r);
-
-        return r;
-    }
-
-    void timer_base::unregister_resource(registration_ptr_w& p_value)
-    {
-        auto s = p_value.lock();
-        p_value.reset();
-        if (s)
-            s->owner._registrations.lock()->erase(s);
-    }
-
-    timer_base::storage& timer_base::local_storage()
-    {
-        thread_local storage value;
-        return value;
-    }
-
-} } }
diff --git a/include/asyncpp/timing/impl/timer_impl.h b/include/asyncpp/timing/impl/timer_impl.h
deleted file mode 100644
index c0a4525..0000000
--- a/include/asyncpp/timing/impl/timer_impl.h
+++ /dev/null
@@ -1,80 +0,0 @@
-#pragma once
-
-namespace asyncpp {
-namespace timing {
-
-    template<typename T_inner = void>
-    struct timer;
-
-    namespace __impl
-    {
-
-        /* timer_impl - default */
-
-        template<typename T_inner>
-        struct timer_impl
-        {
-        public:
-            using inner_type                = T_inner;
-            using owner_type                = timer<inner_type>;
-            using inner_thread_lock_type    = decltype(std::declval<inner_type>().init_thread());
-
-            struct thread_lock
-            {
-                inner_thread_lock_type inner_lock;
-
-                template<typename... X_args>
-                inline thread_lock(X_args&&... p_args);
-
-                inline ~thread_lock();
-            };
-
-            using thread_lock_ptr_u = std::unique_ptr<thread_lock>;
-
-        public:
-            owner_type& owner;
-            inner_type  inner;
-
-        public:
-            template<typename... X_args>
-            inline timer_impl(
-                owner_type& p_owner,
-                X_args&&... p_args);
-
-            inline void idle(
-                const time_point * p_deadline);
-
-            inline thread_lock_ptr_u init_thread();
-        };
-
-        /* timer_impl<void> */
-
-        template<>
-        struct timer_impl<void>
-        {
-        public:
-            using owner_type = timer<void>;
-
-            struct thread_lock
-            {
-                inline ~thread_lock();
-            };
-
-            using thread_lock_ptr_u = std::unique_ptr<thread_lock>;
-
-        public:
-            owner_type& owner;
-
-        public:
-            inline timer_impl(
-                owner_type& p_owner);
-
-            inline void idle(
-                const time_point * p_deadline);
-
-            inline thread_lock_ptr_u init_thread();
-        };
-
-    }
-
-} }
diff --git a/include/asyncpp/timing/impl/timer_impl.inl b/include/asyncpp/timing/impl/timer_impl.inl
deleted file mode 100644
index 0dce7a7..0000000
--- a/include/asyncpp/timing/impl/timer_impl.inl
+++ /dev/null
@@ -1,73 +0,0 @@
-#pragma once
-
-#include "timer_impl.h"
-
-namespace asyncpp {
-namespace timing {
-namespace __impl {
-
-    /* timer_impl::thread_lock - default */
-
-    template<typename T_inner>
-    template<typename... X_args>
-    timer_impl<T_inner>::thread_lock::thread_lock(X_args&&... p_args)
-        : inner_lock(std::forward<X_args>(p_args)...)
-        { }
-
-    template<typename T_inner>
-    timer_impl<T_inner>::thread_lock::~thread_lock()
-        { owner_type::local_storage().current = nullptr; }
-
-    /* timer_impl - default */
-
-    template<typename T_inner>
-    template<typename... X_args>
-    timer_impl<T_inner>::timer_impl(
-        owner_type& p_owner,
-        X_args&&... p_args)
-        : owner(p_owner)
-        , inner(std::forward<X_args>(p_args)...)
-        { }
-
-    template<typename T_inner>
-    void timer_impl<T_inner>::idle(const time_point * p_deadline)
-    {
-        {
-        auto r = owner._registrations.lock();
-        if (!r->empty())
-        {
-            p_deadline = merge_deadlines(p_deadline, &(*r->begin())->deadline);
-        }
-        }
-
-        inner.idle(p_deadline);
-    }
-
-    template<typename T_inner>
-    typename timer_impl<T_inner>::thread_lock_ptr_u
-    timer_impl<T_inner>::init_thread()
-        { return std::make_unique<thread_lock>(inner.init_thread()); }
-
-
-
-    /* timer_impl<void>::thread_lock - default */
-
-    timer_impl<void>::thread_lock::~thread_lock()
-        { owner_type::local_storage().current = nullptr; }
-
-    /* timer_impl<void> */
-
-    timer_impl<void>::timer_impl(
-        owner_type& p_owner)
-        : owner(p_owner)
-        { }
-
-    void timer_impl<void>::idle(
-        const time_point * p_deadline)
-        { }
-
-    timer_impl<void>::thread_lock_ptr_u
-    timer_impl<void>::init_thread()
-        { return std::unique_ptr<thread_lock>(); }
-
-} } }
diff --git a/include/asyncpp/timing/interval.h b/include/asyncpp/timing/interval.h
index f2a055d..cde80ca 100644
--- a/include/asyncpp/timing/interval.h
+++ b/include/asyncpp/timing/interval.h
@@ -1,55 +1,5 @@
 #pragma once
 
-#include <asyncpp/core/misc.h>
-#include <asyncpp/core/future/future.h>
-#include <asyncpp/core/stream/stream.h>
+#include "interval/interval.h"
 
-#include "delay.h"
-
-namespace asyncpp {
-namespace timing {
-
-    struct interval final
-        : public base_stream<void, interval>
-    {
-    public:
-        using value_type        = void;
-        using base_stream_type  = base_stream<void, delay>;
-        using result_type       = typename base_stream_type::result_type;
-
-    private:
-        delay               _delay;     //!< Delay future
-        clock::duration     _duration;  //!< Interval duration.
-        time_point          _deadline;  //!< Deadline after the interval should end.
-
-    public:
-        /**
-         * @brief Constructor.
-         */
-        template<typename T_base, typename T_ratio>
-        inline interval(
-            const duration<T_base, T_ratio>&    p_duration,
-            time_point                          p_deadline = time_point());
-
-        /**
-         * @brief Constructor.
-         */
-        template<typename T_base, typename T_ratio>
-        inline interval(
-            const time_point&                   p_at,
-            const duration<T_base, T_ratio>&    p_duration,
-            time_point                          p_deadline = time_point());
-
-        /**
-         * @brief Get the duration of the interval.
-         */
-        inline const clock::duration& duration() const;
-
-    public: /* stream */
-        /**
-         * @brief Poll the result from the stream.
-         */
-        inline result_type poll();
-    };
-
-} }
+#include "interval/interval.inl"
diff --git a/include/asyncpp/timing/interval/interval.h b/include/asyncpp/timing/interval/interval.h
new file mode 100644
index 0000000..912cb0a
--- /dev/null
+++ b/include/asyncpp/timing/interval/interval.h
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <asyncpp/core/misc.h>
+#include <asyncpp/core/future/future.h>
+#include <asyncpp/core/stream/stream.h>
+
+#include "../delay/delay.h"
+
+namespace asyncpp {
+namespace timing {
+
+    struct interval final
+        : public base_stream<void, interval>
+    {
+    public:
+        using value_type        = void;
+        using base_stream_type  = base_stream<void, delay>;
+        using result_type       = typename base_stream_type::result_type;
+
+    private:
+        delay               _delay;     //!< Delay future
+        clock::duration     _duration;  //!< Interval duration.
+        time_point          _deadline;  //!< Deadline after the interval should end.
+
+    public:
+        /**
+         * @brief Constructor.
+         */
+        template<typename T_base, typename T_ratio>
+        inline interval(
+            const duration<T_base, T_ratio>&    p_duration,
+            time_point                          p_deadline = time_point());
+
+        /**
+         * @brief Constructor.
+         */
+        template<typename T_base, typename T_ratio>
+        inline interval(
+            const time_point&                   p_at,
+            const duration<T_base, T_ratio>&    p_duration,
+            time_point                          p_deadline = time_point());
+
+        /**
+         * @brief Get the duration of the interval.
+         */
+        inline const clock::duration& duration() const;
+
+    public: /* stream */
+        /**
+         * @brief Poll the result from the stream.
+         */
+        inline result_type poll();
+    };
+
+} }
diff --git a/include/asyncpp/timing/interval.inl b/include/asyncpp/timing/interval/interval.inl
similarity index 97%
rename from include/asyncpp/timing/interval.inl
rename to include/asyncpp/timing/interval/interval.inl
index 8b1e17b..824c47b 100644
--- a/include/asyncpp/timing/interval.inl
+++ b/include/asyncpp/timing/interval/interval.inl
@@ -2,7 +2,7 @@
 
 #include "interval.h"
 
-#include "delay.inl"
+#include "../delay/delay.inl"
 
 namespace asyncpp {
 namespace timing {
diff --git a/include/asyncpp/timing/timeout.h b/include/asyncpp/timing/timeout.h
index cda3839..6c44817 100644
--- a/include/asyncpp/timing/timeout.h
+++ b/include/asyncpp/timing/timeout.h
@@ -1,103 +1,9 @@
 #pragma once
 
-#include <cppcore/misc/exception.h>
+#include "timeout/misc.h"
+#include "timeout/timeout_future.h"
+#include "timeout/timeout_stream.h"
 
-#include <asyncpp/core/misc.h>
-#include <asyncpp/core/future/future.h>
-#include <asyncpp/core/stream/stream.h>
-
-#include "delay.h"
-
-namespace asyncpp {
-namespace timing {
-
-    struct timeout_exception
-        : public cppcore::exception
-    {
-    public:
-        /**
-         * @brief Constructor.
-         */
-        inline timeout_exception();
-    };
-
-    template<typename T_inner>
-    struct timeout;
-
-    namespace __impl
-    {
-
-        template<
-            typename T_derived,
-            typename = void>
-        struct timeout_impl;
-
-        template<
-            typename T_inner>
-        struct timeout_impl<
-            timeout<T_inner>,
-            std::enable_if_t<is_future_v<std::decay_t<T_inner>>>>
-            : public base_future<
-                typename std::decay_t<T_inner>::value_type,
-                timeout<T_inner>>
-        {
-        private:
-            using derived_type = timeout<T_inner>;
-
-        public:
-            auto poll();
-        };
-
-        template<
-            typename T_inner>
-        struct timeout_impl<
-            timeout<T_inner>,
-            std::enable_if_t<is_stream_v<std::decay_t<T_inner>>>>
-            : public base_stream<
-                typename std::decay_t<T_inner>::value_type,
-                timeout<T_inner>>
-        {
-        private:
-            using derived_type = timeout<T_inner>;
-
-        public:
-            auto poll();
-        };
-
-    }
-
-    template<typename T_inner>
-    struct timeout final
-        : public __impl::timeout_impl<timeout<T_inner>>
-    {
-    public:
-        using inner_type = T_inner;
-        using value_type = typename std::decay_t<inner_type>::value_type;
-        using this_type  = timeout<inner_type>;
-        using impl_type  = __impl::timeout_impl<this_type>;
-
-        friend impl_type;
-
-    private:
-        inner_type      _inner;     //!< Inner future / stream.
-        clock::duration _timeout;   //!< Timeout.
-        delay           _delay;     //!< Delay future.
-
-    public:
-        /**
-         * @brief Constructor.
-         */
-        template<typename X_inner, typename X_base, typename X_ratio>
-        inline timeout(
-            X_inner&&                           p_inner,
-            const duration<X_base, X_ratio>&    p_timeout);
-
-        /**
-         * @brief Reset the deadline.
-         */
-        template<typename X_base, typename X_ratio>
-        inline void reset(
-            const duration<X_base, X_ratio>& p_timeout);
-    };
-
-} }
+#include "timeout/misc.inl"
+#include "timeout/timeout_future.inl"
+#include "timeout/timeout_stream.inl"
diff --git a/include/asyncpp/timing/timeout.inl b/include/asyncpp/timing/timeout.inl
deleted file mode 100644
index 6c79e7f..0000000
--- a/include/asyncpp/timing/timeout.inl
+++ /dev/null
@@ -1,96 +0,0 @@
-#pragma once
-
-#include "timeout.h"
-
-namespace asyncpp {
-namespace timing {
-
-    namespace __impl
-    {
-
-        template<
-            typename T_inner>
-        auto timeout_impl<
-            timeout<T_inner>,
-            std::enable_if_t<is_future_v<std::decay_t<T_inner>>>>
-            ::poll()
-        {
-            auto& self = static_cast<derived_type&>(*this);
-            auto r = self._inner.poll();
-
-            if (    r.is_not_ready()
-                &&  self._delay.poll())
-            {
-                auto new_deadline = self._delay.deadline() + self._timeout;
-                self._delay.reset(new_deadline);
-                throw timing::timeout_exception();
-            }
-
-            return r;
-        }
-
-
-        template<
-            typename T_inner>
-        auto timeout_impl<
-            timeout<T_inner>,
-            std::enable_if_t<is_stream_v<std::decay_t<T_inner>>>>
-            ::poll()
-        {
-            auto& self = static_cast<derived_type&>(*this);
-            auto r = self._inner.poll();
-
-            if (r.is_not_ready())
-            {
-                if (self._delay.poll())
-                {
-                    self._delay.reset(self._timeout);
-                    throw timing::timeout_exception();
-                }
-            }
-            else
-            {
-                self._delay.reset(self._timeout);
-            }
-
-            return r;
-        }
-
-    }
-
-    /* timeout_exception */
-
-    timeout_exception::timeout_exception()
-        : cppcore::exception::exception("timeout")
-        { }
-
-    /* timer */
-
-    template<
-        typename T_inner>
-    template<
-        typename X_inner,
-        typename X_base,
-        typename X_ratio>
-    timeout<T_inner>
-        ::timeout(
-            X_inner&&                           p_inner,
-            const duration<X_base, X_ratio>&    p_duration)
-            : _inner    (std::forward<X_inner>(p_inner))
-            , _timeout  (p_duration)
-            , _delay    (asyncpp::now() + p_duration)
-        { }
-
-    template<
-        typename T_inner>
-    template<
-        typename X_base,
-        typename X_ratio>
-    void timeout<T_inner>
-        ::reset(const duration<X_base, X_ratio>& p_duration)
-    {
-        _timeout = p_duration;
-        _delay.reset(asyncpp::now() + p_duration);
-    }
-
-} }
diff --git a/include/asyncpp/timing/timeout/misc.h b/include/asyncpp/timing/timeout/misc.h
new file mode 100644
index 0000000..c1789ed
--- /dev/null
+++ b/include/asyncpp/timing/timeout/misc.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <cppcore/misc/exception.h>
+
+namespace asyncpp {
+namespace timing {
+
+    struct timeout_exception
+        : public cppcore::exception
+    {
+    public:
+        /**
+         * @brief Constructor.
+         */
+        inline timeout_exception();
+    };
+
+} }
diff --git a/include/asyncpp/timing/timeout/misc.inl b/include/asyncpp/timing/timeout/misc.inl
new file mode 100644
index 0000000..ac690a2
--- /dev/null
+++ b/include/asyncpp/timing/timeout/misc.inl
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "misc.h"
+
+namespace asyncpp {
+namespace timing {
+
+    /* timeout_exception */
+
+    timeout_exception::timeout_exception()
+        : cppcore::exception::exception("timeout")
+        { }
+
+} }
diff --git a/include/asyncpp/timing/timeout/timeout_future.h b/include/asyncpp/timing/timeout/timeout_future.h
new file mode 100644
index 0000000..bfd1184
--- /dev/null
+++ b/include/asyncpp/timing/timeout/timeout_future.h
@@ -0,0 +1,50 @@
+#pragma once
+
+#include <asyncpp/core/future/future.h>
+
+#include "../delay/delay.h"
+
+namespace asyncpp {
+namespace timing {
+
+    template<typename T_inner>
+    struct timeout_future final
+        : public base_future<
+            typename std::decay_t<T_inner>::value_type,
+            timeout_future<T_inner>>
+    {
+    public:
+        using inner_type        = T_inner;
+        using value_type        = typename std::decay_t<inner_type>::value_type;
+        using this_type         = timeout_future<inner_type>;
+        using base_future_type  = base_future<value_type, this_type>;
+        using result_type       = typename base_future_type::result_type;
+
+    private:
+        inner_type      _inner;     //!< Inner future.
+        clock::duration _timeout;   //!< Timeout.
+        delay           _delay;     //!< Delay future.
+
+    public:
+        /**
+         * @brief Constructor.
+         */
+        template<typename X_inner, typename X_base, typename X_ratio>
+        inline timeout_future(
+            X_inner&&                           p_inner,
+            const duration<X_base, X_ratio>&    p_timeout);
+
+        /**
+         * @brief Reset the deadline.
+         */
+        template<typename X_base, typename X_ratio>
+        inline void reset(
+            const duration<X_base, X_ratio>& p_timeout);
+
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
+    };
+
+} }
diff --git a/include/asyncpp/timing/timeout/timeout_future.inl b/include/asyncpp/timing/timeout/timeout_future.inl
new file mode 100644
index 0000000..95c16b0
--- /dev/null
+++ b/include/asyncpp/timing/timeout/timeout_future.inl
@@ -0,0 +1,55 @@
+#pragma once
+
+#include "timeout_future.h"
+
+namespace asyncpp {
+namespace timing {
+
+    /* timeout_future */
+
+    template<
+        typename T_inner>
+    template<
+        typename X_inner,
+        typename X_base,
+        typename X_ratio>
+    timeout_future<T_inner>::timeout_future(
+        X_inner&&                           p_inner,
+        const duration<X_base, X_ratio>&    p_timeout)
+        : _inner    (std::forward<X_inner>(p_inner))
+        , _timeout  (p_timeout)
+        , _delay    (asyncpp::now() + p_timeout)
+        { }
+
+    template<
+        typename T_inner>
+    template<
+        typename X_base,
+        typename X_ratio>
+    void timeout_future<T_inner>
+        ::reset(const duration<X_base, X_ratio>& p_timeout)
+    {
+        _timeout = p_timeout;
+        _delay.reset(_timeout);
+    }
+
+    template<
+        typename T_inner>
+    typename timeout_future<T_inner>::result_type
+    timeout_future<T_inner>
+        ::poll()
+    {
+        auto r = _inner.poll();
+
+        if (    r.is_not_ready()
+            &&  _delay.poll())
+        {
+            auto new_deadline = _delay.deadline() + _timeout;
+            _delay.reset(new_deadline);
+            throw timing::timeout_exception();
+        }
+
+        return r;
+    }
+
+} }
diff --git a/include/asyncpp/timing/timeout/timeout_stream.h b/include/asyncpp/timing/timeout/timeout_stream.h
new file mode 100644
index 0000000..7d9a391
--- /dev/null
+++ b/include/asyncpp/timing/timeout/timeout_stream.h
@@ -0,0 +1,50 @@
+#pragma once
+
+#include <asyncpp/core/stream/stream.h>
+
+#include "../delay/delay.h"
+
+namespace asyncpp {
+namespace timing {
+
+    template<typename T_inner>
+    struct timeout_stream final
+        : public base_stream<
+            typename std::decay_t<T_inner>::value_type,
+            timeout_stream<T_inner>>
+    {
+    public:
+        using inner_type        = T_inner;
+        using value_type        = typename std::decay_t<inner_type>::value_type;
+        using this_type         = timeout_stream<inner_type>;
+        using base_stream_type  = base_stream<value_type, this_type>;
+        using result_type       = typename base_stream_type::result_type;
+
+    private:
+        inner_type      _inner;     //!< Inner stream.
+        clock::duration _timeout;   //!< Timeout.
+        delay           _delay;     //!< Delay stream.
+
+    public:
+        /**
+         * @brief Constructor.
+         */
+        template<typename X_inner, typename X_base, typename X_ratio>
+        inline timeout_stream(
+            X_inner&&                           p_inner,
+            const duration<X_base, X_ratio>&    p_timeout);
+
+        /**
+         * @brief Reset the deadline.
+         */
+        template<typename X_base, typename X_ratio>
+        inline void reset(
+            const duration<X_base, X_ratio>& p_timeout);
+
+        /**
+         * @brief Poll the result from the future.
+         */
+        inline result_type poll();
+    };
+
+} }
diff --git a/include/asyncpp/timing/timeout/timeout_stream.inl b/include/asyncpp/timing/timeout/timeout_stream.inl
new file mode 100644
index 0000000..10cc2f4
--- /dev/null
+++ b/include/asyncpp/timing/timeout/timeout_stream.inl
@@ -0,0 +1,60 @@
+#pragma once
+
+#include "timeout_stream.h"
+
+namespace asyncpp {
+namespace timing {
+
+    /* timeout_stream */
+
+    template<
+        typename T_inner>
+    template<
+        typename X_inner,
+        typename X_base,
+        typename X_ratio>
+    timeout_stream<T_inner>::timeout_stream(
+        X_inner&&                           p_inner,
+        const duration<X_base, X_ratio>&    p_timeout)
+        : _inner    (std::forward<X_inner>(p_inner))
+        , _timeout  (p_timeout)
+        , _delay    (asyncpp::now() + p_timeout)
+        { }
+
+    template<
+        typename T_inner>
+    template<
+        typename X_base,
+        typename X_ratio>
+    void timeout_stream<T_inner>
+        ::reset(const duration<X_base, X_ratio>& p_timeout)
+    {
+        _timeout = p_timeout;
+        _delay.reset(_timeout);
+    }
+
+    template<
+        typename T_inner>
+    typename timeout_stream<T_inner>::result_type
+    timeout_stream<T_inner>
+        ::poll()
+    {
+        auto r = _inner.poll();
+
+        if (r.is_not_ready())
+        {
+            if (_delay.poll())
+            {
+                _delay.reset(_timeout);
+                throw timing::timeout_exception();
+            }
+        }
+        else
+        {
+            _delay.reset(_timeout);
+        }
+
+        return r;
+    }
+
+} }
diff --git a/include/asyncpp/timing/timer.h b/include/asyncpp/timing/timer.h
index cca6831..bbd2313 100644
--- a/include/asyncpp/timing/timer.h
+++ b/include/asyncpp/timing/timer.h
@@ -1,50 +1,11 @@
 #pragma once
 
-#include <set>
-#include <memory>
-
-#include <cppcore/synchronization/locked.h>
-
-#include "impl/timer_base.h"
-#include "impl/timer_impl.h"
-#include "impl/registration.h"
-
-namespace asyncpp {
-namespace timing {
-
-    template<typename T_inner>
-    struct timer
-        : public __impl::timer_base
-    {
-    public:
-        template<typename X>
-        friend struct __impl::timer_impl;
-
-        using inner_type        = T_inner;
-        using timer_impl_type   = __impl::timer_impl<inner_type>;
-
-    private:
-        timer_impl_type _impl;
-
-    public:
-        /**
-         * @brief Constructor.
-         */
-        template<typename... X_args>
-        inline timer(X_args&&... p_args);
-
-        /**
-         * @brief Handle idle of the runtime.
-         *
-         * This method is called as soon as the runtime has nothing to do.
-         * The passed deadline is the timepoint the method should return (or null if not set).
-         */
-        inline void idle(const time_point * p_deadline);
-
-        /**
-         * @brief This method is calld by the executor when a new thread needs to be initialized.
-         */
-        inline decltype(auto) init_thread();
-    };
-
-} }
+#include "timer/timer.h"
+#include "timer/timer_base.h"
+#include "timer/timer_impl.h"
+#include "timer/resource.h"
+
+#include "timer/timer.inl"
+#include "timer/timer_base.inl"
+#include "timer/timer_impl.inl"
+#include "timer/resource.inl"
diff --git a/include/asyncpp/timing/impl/registration.h b/include/asyncpp/timing/timer/resource.h
similarity index 74%
rename from include/asyncpp/timing/impl/registration.h
rename to include/asyncpp/timing/timer/resource.h
index 9c8155e..b767d98 100644
--- a/include/asyncpp/timing/impl/registration.h
+++ b/include/asyncpp/timing/timer/resource.h
@@ -11,7 +11,7 @@ namespace asyncpp {
 namespace timing {
 namespace __impl {
 
-    struct registration
+    struct resource
     {
     public:
         timer_base&         owner;
@@ -21,13 +21,13 @@ namespace __impl {
         /**
          * @brief Constructor.
          */
-        inline registration(
+        inline resource(
             timer_base&             p_owner,
             const time_point&       p_deadline,
             const asyncpp::task&    p_task);
     };
 
-    using registration_ptr_w = std::weak_ptr<registration>;
-    using registration_ptr_s = std::shared_ptr<registration>;
+    using resource_ptr_w = std::weak_ptr<resource>;
+    using resource_ptr_s = std::shared_ptr<resource>;
 
 } } }
diff --git a/include/asyncpp/timing/impl/registration.inl b/include/asyncpp/timing/timer/resource.inl
similarity index 79%
rename from include/asyncpp/timing/impl/registration.inl
rename to include/asyncpp/timing/timer/resource.inl
index b19be9b..70aafc0 100644
--- a/include/asyncpp/timing/impl/registration.inl
+++ b/include/asyncpp/timing/timer/resource.inl
@@ -1,14 +1,14 @@
 #pragma once
 
-#include "registration.h"
+#include "resource.h"
 
 namespace asyncpp {
 namespace timing {
 namespace __impl {
 
-    /* registration */
+    /* resource */
 
-    registration::registration(
+    resource::resource(
         timer_base&             p_owner,
         const time_point&       p_deadline,
         const asyncpp::task&    p_task)
diff --git a/include/asyncpp/timing/timer/timer.h b/include/asyncpp/timing/timer/timer.h
new file mode 100644
index 0000000..0dffe7c
--- /dev/null
+++ b/include/asyncpp/timing/timer/timer.h
@@ -0,0 +1,44 @@
+#pragma once
+
+#include <set>
+#include <memory>
+
+#include <cppcore/synchronization/locked.h>
+
+#include "timer_impl.h"
+
+namespace asyncpp {
+namespace timing {
+
+    template<typename T_inner = void>
+    struct timer
+        : public __impl::timer_impl<T_inner>
+    {
+    public:
+        using base_type  = __impl::timer_impl<T_inner>;
+        using inner_type = T_inner;
+
+    public:
+        /**
+         * @brief Constructor.
+         */
+        template<typename... X_args>
+        inline timer(X_args&&... p_args);
+
+        /**
+         * @brief Handle idle of the runtime.
+         *
+         * This method is called as soon as the runtime has nothing to do.
+         * The passed deadline is the timepoint the method should return (or null if not set).
+         */
+        inline void idle(const time_point * p_deadline);
+
+        /**
+         * @brief This method is calld by the executor when a new thread needs to be initialized.
+         *
+         * @return Object to hold as long as the thread is active on this timer.
+         */
+        inline auto init_thread();
+    };
+
+} }
diff --git a/include/asyncpp/timing/timer.inl b/include/asyncpp/timing/timer/timer.inl
similarity index 60%
rename from include/asyncpp/timing/timer.inl
rename to include/asyncpp/timing/timer/timer.inl
index 0549928..8cfb160 100644
--- a/include/asyncpp/timing/timer.inl
+++ b/include/asyncpp/timing/timer/timer.inl
@@ -1,11 +1,8 @@
 #pragma once
 
 #include "timer.h"
-#include "delay.inl"
 
-#include "impl/timer_base.inl"
-#include "impl/timer_impl.inl"
-#include "impl/registration.inl"
+#include "timer_impl.inl"
 
 namespace asyncpp {
 namespace timing {
@@ -15,7 +12,7 @@ namespace timing {
     template<typename T_inner>
     template<typename... X_args>
     timer<T_inner>::timer(X_args&&... p_args)
-        : _impl(*this, std::forward<X_args>(p_args)...)
+        : base_type(std::forward<X_args>(p_args)...)
         { }
 
     template<typename T_inner>
@@ -24,7 +21,7 @@ namespace timing {
         auto now = asyncpp::now();
 
         {
-        auto r = _registrations.lock();
+        auto r = this->_resources.lock();
         auto it = r->begin();
         while (it != r->end() && now >= (**it).deadline)
         {
@@ -33,14 +30,11 @@ namespace timing {
         }
         }
 
-        _impl.idle(p_deadline);
+        base_type::idle_impl(p_deadline);
     }
 
     template<typename T_inner>
-    decltype(auto) timer<T_inner>::init_thread()
-    {
-        local_storage().current = this;
-        return _impl.init_thread();
-    }
+    auto timer<T_inner>::init_thread()
+        { return base_type::init_thread_impl(); }
 
 } }
diff --git a/include/asyncpp/timing/timer/timer_base.h b/include/asyncpp/timing/timer/timer_base.h
new file mode 100644
index 0000000..cbe8e48
--- /dev/null
+++ b/include/asyncpp/timing/timer/timer_base.h
@@ -0,0 +1,87 @@
+#pragma once
+
+#include <set>
+#include <memory>
+
+#include <cppcore/synchronization/locked.h>
+
+#include <asyncpp/core/misc.h>
+
+#include "timer_base.pre.h"
+#include "resource.h"
+
+namespace asyncpp {
+namespace timing {
+namespace __impl {
+
+    struct timer_base
+    {
+    private:
+        struct resource_less_compare
+        {
+            constexpr bool operator()(
+                const resource_ptr_s& lhs,
+                const resource_ptr_s& rhs) const;
+        };
+
+        using resource_set = std::set<resource_ptr_s, resource_less_compare>;
+
+    protected:
+        cppcore::locked<resource_set> _resources;
+
+    public:
+        /**
+         * @brief Get the number of registered timing resources.
+         */
+        inline size_t resource_count();
+
+    public:
+        /**
+         * @brief Get the thread local timer_base instance.
+         */
+        static inline timer_base* current();
+
+        /**
+         * @brief Register a new resource within this timer_base.
+         */
+        static inline resource_ptr_w register_resource(const time_point& p_deadline);
+
+        /**
+         * @brief Register a new resource within this timer_base.
+         */
+        static inline void unregister_resource(resource_ptr_w& p_value);
+
+    private:
+        /**
+         * @brief Create resource for a new resource.
+         */
+        resource_ptr_w create_resource(const time_point& p_deadline);
+
+    public:
+        struct lock
+        {
+        public:
+            /**
+             * @brief Constructor.
+             */
+            inline lock(timer_base& p_timer);
+
+            /**
+             * @brief Destructor.
+             */
+            inline ~lock();
+        };
+
+    private:
+        struct storage
+        {
+            timer_base* current { nullptr };
+        };
+
+        /**
+         * @brief Get the thread local storage.
+         */
+        static inline storage& local_storage();
+    };
+
+} } }
diff --git a/include/asyncpp/timing/timer/timer_base.inl b/include/asyncpp/timing/timer/timer_base.inl
new file mode 100644
index 0000000..f50d295
--- /dev/null
+++ b/include/asyncpp/timing/timer/timer_base.inl
@@ -0,0 +1,83 @@
+#pragma once
+
+#include <cppcore/misc/exception.h>
+
+#include "timer_base.h"
+
+namespace asyncpp {
+namespace timing {
+namespace __impl {
+
+    /* timer_base::inner_less_compare */
+
+    constexpr bool timer_base::resource_less_compare::operator()(
+        const resource_ptr_s& lhs,
+        const resource_ptr_s& rhs) const
+    {
+        return  (lhs->deadline <  rhs->deadline)
+                    ?  true
+                    :
+                (lhs->deadline == rhs->deadline)
+            &&  (lhs.get()     <  rhs.get())
+                    ?   true
+                    :   false;
+    }
+
+    /* timer_base::lock */
+
+    timer_base::lock::lock(timer_base& p_timer)
+    {
+        auto& current = timer_base::local_storage().current;
+        if (current)
+            throw cppcore::invalid_operation_exception("Current timer is already assigned!");
+        current = &p_timer;
+    }
+
+    timer_base::lock::~lock()
+        { timer_base::local_storage().current = nullptr; }
+
+    /* timer_base */
+
+    size_t timer_base::resource_count()
+        { return _resources.lock()->size(); }
+
+    timer_base* timer_base::current()
+        { return local_storage().current; }
+
+    resource_ptr_w timer_base::register_resource(const time_point& p_deadline)
+    {
+        auto t = current();
+
+        if (!t)
+            throw cppcore::invalid_operation_exception("Thread local timer_base instance is not assigned!");
+
+        return t->create_resource(p_deadline);
+    }
+
+    void timer_base::unregister_resource(resource_ptr_w& p_value)
+    {
+        auto s = p_value.lock();
+        p_value.reset();
+        if (s)
+            s->owner._resources.lock()->erase(s);
+    }
+
+    resource_ptr_w timer_base::create_resource(const time_point& p_deadline)
+    {
+        auto r = std::make_shared<resource>(
+            *this,
+            p_deadline,
+            task::current());
+
+        _resources.lock()->insert(r);
+
+        return r;
+    }
+
+    timer_base::storage& timer_base::local_storage()
+    {
+        thread_local storage value;
+        return value;
+    }
+
+} } }
diff --git a/include/asyncpp/timing/impl/timer_base.pre.h b/include/asyncpp/timing/timer/timer_base.pre.h
similarity index 100%
rename from include/asyncpp/timing/impl/timer_base.pre.h
rename to include/asyncpp/timing/timer/timer_base.pre.h
diff --git a/include/asyncpp/timing/timer/timer_impl.h b/include/asyncpp/timing/timer/timer_impl.h
new file mode 100644
index 0000000..68fe3d9
--- /dev/null
+++ b/include/asyncpp/timing/timer/timer_impl.h
@@ -0,0 +1,10 @@
+#pragma once
+
+namespace asyncpp {
+namespace timing {
+namespace __impl {
+
+    template<typename T_inner>
+    struct timer_impl;
+
+} } }
diff --git a/include/asyncpp/timing/timer/timer_impl.inl b/include/asyncpp/timing/timer/timer_impl.inl
new file mode 100644
index 0000000..1bf4dad
--- /dev/null
+++ b/include/asyncpp/timing/timer/timer_impl.inl
@@ -0,0 +1,76 @@
+#pragma once
+
+#include "timer_impl.h"
+#include "timer_base.h"
+
+namespace asyncpp {
+namespace timing {
+namespace __impl {
+
+    /* timer_impl - default */
+
+    template<typename T_inner>
+    struct timer_impl
+        : public timer_base
+    {
+    public:
+        using inner_type                = T_inner;
+        using inner_thread_lock_type    = decltype(std::declval<inner_type>().init_thread());
+
+        struct thread_lock
+        {
+            timer_base::lock        timer_lock;
+            inner_thread_lock_type  inner_lock;
+
+            template<typename... X_args>
+            inline thread_lock(timer_base& p_timer, X_args&&... p_args)
+                : timer_lock(p_timer)
+                , inner_lock(std::forward<X_args>(p_args)...)
+                { }
+
+            inline thread_lock(thread_lock &&) = delete;
+            inline thread_lock(thread_lock const &) = delete;
+        };
+
+    private:
+        inner_type  _inner;
+
+    public:
+        template<typename X_inner>
+        inline timer_impl(X_inner&& p_inner)
+            : _inner(std::forward<X_inner>(p_inner))
+            { }
+
+    protected:
+        inline void idle_impl(const time_point * p_deadline)
+        {
+            {
+            auto r = _resources.lock();
+            if (!r->empty())
+            {
+                p_deadline = merge_deadlines(p_deadline, &(*r->begin())->deadline);
+            }
+            }
+
+            _inner.idle(p_deadline);
+        }
+
+        inline auto init_thread_impl()
+            { return thread_lock(*this, _inner.init_thread()); }
+    };
+
+    /* timer_impl - void */
+
+    template<>
+    struct timer_impl<void>
+        : public timer_base
+    {
+    protected:
+        inline void idle_impl(const time_point * p_deadline)
+            { }
+
+        inline auto init_thread_impl()
+            { return timer_base::lock(*this); }
+    };
+
+} } }
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 975a22a..44aedde 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -9,11 +9,15 @@ Find_Package                        ( cppcore REQUIRED )
 
 # Interface Library ###############################################################################
 
+Set                                 ( ASYNCPP_GENERATED_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/generated )
+Configure_File                      ( ${CMAKE_CURRENT_SOURCE_DIR}/../cmake/config.h.in
+                                      ${ASYNCPP_GENERATED_INCLUDE_DIR}/asyncpp/config.h )
 Set                                 ( ASYNCPP_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../include )
 Add_Library                         ( asyncpp INTERFACE )
 Target_Include_Directories          ( asyncpp
                                       INTERFACE
                                         $<BUILD_INTERFACE:${ASYNCPP_INCLUDE_DIR}>
+                                        $<BUILD_INTERFACE:${ASYNCPP_GENERATED_INCLUDE_DIR}>
                                         $<INSTALL_INTERFACE:${ASYNCPP_INSTALL_DIR_INCLUDE}> )
 Target_Link_Libraries               ( asyncpp
                                       INTERFACE
@@ -31,6 +35,8 @@ If                                  ( ASYNCPP_INSTALL_HEADER )
                                           DESTINATION ${ASYNCPP_INSTALL_DIR_INCLUDE} )
     Install                             ( DIRECTORY ${ASYNCPP_INCLUDE_DIR}/asyncpp
                                           DESTINATION ${ASYNCPP_INSTALL_DIR_INCLUDE} )
+    Install                             ( DIRECTORY ${ASYNCPP_GENERATED_INCLUDE_DIR}/cppcore
+                                          DESTINATION ${ASYNCPP_INSTALL_DIR_INCLUDE} )
     Install                             ( TARGETS asyncpp
                                           EXPORT asyncpp
                                           DESTINATION ${ASYNCPP_INSTALL_DIR_INCLUDE} )
diff --git a/test/asyncpp/executor/current_thread_tests.cpp b/test/asyncpp/executor/current_thread_tests.cpp
index 9f2027b..38562e9 100644
--- a/test/asyncpp/executor/current_thread_tests.cpp
+++ b/test/asyncpp/executor/current_thread_tests.cpp
@@ -3,9 +3,8 @@
 #include "../../helper/now_mock.h"
 #include "../../helper/runtime_mock.h"
 
-#include <asyncpp/timing.h>
-#include <asyncpp/executor/current_thread.h>
 #include <asyncpp.h>
+#include <asyncpp/executor/current_thread.h>
 
 using namespace ::testing;
 using namespace ::asyncpp;
diff --git a/test/asyncpp/timing/delay_tests.cpp b/test/asyncpp/timing/delay_tests.cpp
index 40cd8d3..3626f67 100644
--- a/test/asyncpp/timing/delay_tests.cpp
+++ b/test/asyncpp/timing/delay_tests.cpp
@@ -3,7 +3,6 @@
 #include "../../helper/now_mock.h"
 
 #include <asyncpp.h>
-#include <asyncpp/timing.h>
 
 using namespace ::testing;
 using namespace ::asyncpp;
@@ -19,7 +18,7 @@ TEST(delay_tests, poll)
         .WillOnce(Return(time_point(std::chrono::seconds(1000))));
 
     asyncpp::timing::timer t;
-    t.make_current();
+    timing::__impl::timer_base::lock l(t);
 
     {
     delay f(time_point(std::chrono::seconds(1000)));
diff --git a/test/asyncpp/timing/interval_tests.cpp b/test/asyncpp/timing/interval_tests.cpp
index e86feeb..0d53df6 100644
--- a/test/asyncpp/timing/interval_tests.cpp
+++ b/test/asyncpp/timing/interval_tests.cpp
@@ -3,7 +3,6 @@
 #include "../../helper/now_mock.h"
 
 #include <asyncpp.h>
-#include <asyncpp/timing.h>
 
 using namespace ::testing;
 using namespace ::asyncpp;
@@ -23,7 +22,7 @@ TEST(interval_tests, poll)
     // 20 / 5  = 4
     // 4 x Ready
 
-    t.make_current();
+    timing::__impl::timer_base::lock l(t);
 
     EXPECT_CALL(m, now)
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
diff --git a/test/asyncpp/timing/timeout_tests.cpp b/test/asyncpp/timing/timeout_tests.cpp
index c8d9792..5b45971 100644
--- a/test/asyncpp/timing/timeout_tests.cpp
+++ b/test/asyncpp/timing/timeout_tests.cpp
@@ -2,7 +2,6 @@
 
 #include "../../helper/now_mock.h"
 
-#include <asyncpp/timing.h>
 #include <asyncpp.h>
 
 using namespace ::testing;
@@ -68,8 +67,8 @@ TEST(timeout_tests, poll_future_no_timeout)
     InSequence seq;
     StrictMock<now_mock> m;
 
-    asyncpp::timing::timer tmr;
-    tmr.make_current();
+    timing::timer tmr;
+    timing::__impl::timer_base::lock l(tmr);
 
     EXPECT_CALL(m, now())
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
@@ -101,8 +100,8 @@ TEST(timeout_tests, poll_future_timeout)
     InSequence seq;
     StrictMock<now_mock> m;
 
-    asyncpp::timing::timer tmr;
-    tmr.make_current();
+    timing::timer tmr;
+    timing::__impl::timer_base::lock l(tmr);
 
     EXPECT_CALL(m, now())
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
@@ -133,8 +132,8 @@ TEST(timeout_tests, poll_stream_no_timeout)
     InSequence seq;
     StrictMock<now_mock> m;
 
-    asyncpp::timing::timer tmr;
-    tmr.make_current();
+    timing::timer tmr;
+    timing::__impl::timer_base::lock l(tmr);
 
     EXPECT_CALL(m, now())
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
@@ -183,8 +182,8 @@ TEST(timeout_tests, poll_stream_timeout)
     InSequence seq;
     StrictMock<now_mock> m;
 
-    asyncpp::timing::timer tmr;
-    tmr.make_current();
+    timing::timer tmr;
+    timing::__impl::timer_base::lock l(tmr);
 
     EXPECT_CALL(m, now())
         .WillOnce(Return(time_point(std::chrono::seconds(0))));
diff --git a/test/asyncpp/timing/timer_tests.cpp b/test/asyncpp/timing/timer_tests.cpp
index 9189641..1b10d1c 100644
--- a/test/asyncpp/timing/timer_tests.cpp
+++ b/test/asyncpp/timing/timer_tests.cpp
@@ -4,27 +4,18 @@
 #include "../../helper/runtime_mock.h"
 
 #include <asyncpp.h>
-#include <asyncpp/timing.h>
 
 using namespace ::testing;
 using namespace ::asyncpp;
 
-TEST(timer_tests, current)
+TEST(timer_tests, lock)
 {
-    {
     timing::timer t;
 
     EXPECT_EQ(nullptr, timing::__impl::timer_base::current());
 
-    t.make_current();
-
-    EXPECT_EQ(&t, timing::__impl::timer_base::current());
-
-    t.clear_current();
-
-    EXPECT_EQ(nullptr, timing::__impl::timer_base::current());
-
-    t.make_current();
+    {
+    timing::__impl::timer_base::lock l(t);
 
     EXPECT_EQ(&t, timing::__impl::timer_base::current());
     }
@@ -39,7 +30,7 @@ TEST(timer_tests, resource_registration)
         .WillRepeatedly(Return(time_point(std::chrono::seconds(0))));
 
     timing::timer t;
-    t.make_current();
+    timing::__impl::timer_base::lock l(t);
 
     auto f1 = std::make_unique<timing::delay>(std::chrono::seconds(10));
     auto f2 = std::make_unique<timing::delay>(std::chrono::seconds(20));
@@ -83,7 +74,7 @@ TEST(timer_tests, idle)
     StrictMock<now_mock> nm;
     StrictMock<runtime_mock> rm;
     timing::timer<StrictMock<runtime_mock>&> t(rm);
-    t.make_current();
+    timing::__impl::timer_base::lock l(t);
 
     EXPECT_CALL(nm, now);
     EXPECT_CALL(rm, idle(nullptr));