uhd: Move internal headers to uhdlib/

To avoid the proliferation of additional include directories and
multiple ways of including project-local headers, we now default to
moving all headers that are used across UHD into the uhdlib/
subdirectory.

Some #include statements were also reordered as they were modified for
closer compliance with the coding guidelines.

Internal cpp source files should now include files like this:

    #include <uhdlib/rfnoc/ctrl_iface.hpp>

Reviewed-by: Ashish Chaudhari <ashish.chaudhari@ettus.com>

3 files changed, 991 insertions, 0 deletions

diff --git a/host/lib/include/uhdlib/experts/expert_container.hpp b/host/lib/include/uhdlib/experts/expert_container.hpp
new file mode 100644
index 000000000..c50e45847
--- /dev/null
+++ b/host/lib/include/uhdlib/experts/expert_container.hpp
@@ -0,0 +1,192 @@
+//
+// Copyright 2016 Ettus Research
+// Copyright 2018 Ettus Research, a National Instruments Company
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#ifndef INCLUDED_UHD_EXPERTS_EXPERT_CONTAINER_HPP
+#define INCLUDED_UHD_EXPERTS_EXPERT_CONTAINER_HPP
+
+#include <uhdlib/experts/expert_nodes.hpp>
+#include <uhd/config.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/thread/recursive_mutex.hpp>
+
+namespace uhd { namespace experts {
+
+    enum auto_resolve_mode_t {
+        AUTO_RESOLVE_OFF,
+        AUTO_RESOLVE_ON_READ,
+        AUTO_RESOLVE_ON_WRITE,
+        AUTO_RESOLVE_ON_READ_WRITE
+    };
+
+    class UHD_API expert_container : private boost::noncopyable, public node_retriever_t {
+    public: //Methods
+        typedef boost::shared_ptr<expert_container> sptr;
+
+        virtual ~expert_container() {};
+
+        /*!
+         * Return the name of this container
+         */
+        virtual const std::string& get_name() const = 0;
+
+        /*!
+         * Resolves all the nodes in this expert graph.
+         *
+         * Dependency analysis is performed on the graph and nodes
+         * are resolved in a topologically sorted order to ensure
+         * that no nodes receive stale data.
+         * Nodes and their dependencies are resolved only if they are
+         * dirty i.e. their contained values have changed since the
+         * last resolve.
+         * This call requires an acyclic expert graph.
+         *
+         * \param force If true then ignore dirty state and resolve all nodes
+         * \throws uhd::runtime_error if graph cannot be resolved
+         */
+        virtual void resolve_all(bool force = false) = 0;
+
+        /*!
+         * Resolves all the nodes that depend on the specified node.
+         *
+         * Dependency analysis is performed on the graph and nodes
+         * are resolved in a topologically sorted order to ensure
+         * that no nodes receive stale data.
+         * Nodes and their dependencies are resolved only if they are
+         * dirty i.e. their contained values have changed since the
+         * last resolve.
+         * This call requires an acyclic expert graph.
+         *
+         * \param node_name Name of the node to start resolving from
+         * \throws uhd::lookup_error if node_name not in container
+         * \throws uhd::runtime_error if graph cannot be resolved
+         *
+         */
+        virtual void resolve_from(const std::string& node_name) = 0;
+
+        /*!
+         * Resolves all the specified node and all of its dependencies.
+         *
+         * Dependency analysis is performed on the graph and nodes
+         * are resolved in a topologically sorted order to ensure
+         * that no nodes receive stale data.
+         * Nodes and their dependencies are resolved only if they are
+         * dirty i.e. their contained values have changed since the
+         * last resolve.
+         * This call requires an acyclic expert graph.
+         *
+         * \param node_name Name of the node to resolve
+         * \throws uhd::lookup_error if node_name not in container
+         * \throws uhd::runtime_error if graph cannot be resolved
+         *
+         */
+        virtual void resolve_to(const std::string& node_name) = 0;
+
+        /*!
+         * Return a node retriever object for this container
+         */
+        virtual const node_retriever_t& node_retriever() const = 0;
+
+        /*!
+         * Returns a DOT (graph description language) representation
+         * of the expert graph. The output has labels for the node
+         * name, node type (data or worker) and the underlying
+         * data type for each node.
+         *
+         */
+        virtual std::string to_dot() const = 0;
+
+        /*!
+         * Runs several sanity checks on the underlying graph to
+         * flag dependency issues. Outputs of the checks are
+         * logged to the console so UHD_EXPERTS_VERBOSE_LOGGING
+         * must be enabled to see the results
+         *
+         */
+        virtual void debug_audit() const = 0;
+
+    private:
+        /*!
+         * Lookup a node with the specified name in the contained graph
+         *
+         * If the node is found, a reference to the node is returned.
+         * If the node is not found, uhd::lookup_error is thrown
+         * lookup can return a data or a worker node
+         * \implements uhd::experts::node_retriever_t
+         *
+         * \param name Name of the node to find
+         *
+         */
+        virtual const dag_vertex_t& lookup(const std::string& name) const = 0;
+        virtual dag_vertex_t& retrieve(const std::string& name) const = 0;
+
+        /*!
+         * expert_factory is a friend of expert_container and
+         * handles all operations that change the structure of
+         * the underlying dependency graph.
+         * The expert_container instance owns all data and worker
+         * nodes and is responsible for release storage on destruction.
+         * However, the expert_factory allocates storage for the
+         * node and passes them into the expert_container using the
+         * following "protected" API calls.
+         *
+         */
+        friend class expert_factory;
+
+        /*!
+         * Creates an empty instance of expert_container with the
+         * specified name.
+         *
+         * \param name Name of the container
+         */
+        static sptr make(const std::string& name);
+
+        /*!
+         * Returns a reference to the resolver mutex.
+         *
+         * The resolver mutex guarantees that external operations
+         * to data-nodes are serialized with resolves of this
+         * container.
+         *
+         */
+        virtual boost::recursive_mutex& resolve_mutex() = 0;
+
+        /*!
+         * Add a data node to the expert graph
+         *
+         * \param data_node Pointer to a fully constructed data node object
+         * \resolve_mode Auto resolve options: Choose from "disabled" and resolve on "read", "write" or "both"
+         * \throws uhd::runtime_error if node already exists or is of a wrong type (recoverable)
+         * \throws uhd::assertion_error for other failures (unrecoverable. will clear the graph)
+         *
+         */
+        virtual void add_data_node(dag_vertex_t* data_node, auto_resolve_mode_t resolve_mode = AUTO_RESOLVE_OFF) = 0;
+
+        /*!
+         * Add a worker node to the expert graph
+         *
+         * \param worker Pointer to a fully constructed worker object
+         * \throws uhd::runtime_error if worker already exists or is of a wrong type (recoverable)
+         * \throws uhd::assertion_error for other failures (unrecoverable. will clear the graph)
+         *
+         */
+        virtual void add_worker(worker_node_t* worker) = 0;
+
+        /*!
+         * Release all storage for this object. This will delete all contained
+         * data and worker nodes and remove all dependency relationship and
+         * resolve callbacks.
+         *
+         * The object will be restored to its newly constructed state. Will not
+         * throw.
+         */
+        virtual void clear() = 0;
+    };
+
+}}
+
+#endif /* INCLUDED_UHD_EXPERTS_EXPERT_CONTAINER_HPP */
diff --git a/host/lib/include/uhdlib/experts/expert_factory.hpp b/host/lib/include/uhdlib/experts/expert_factory.hpp
new file mode 100644
index 000000000..72798eccc
--- /dev/null
+++ b/host/lib/include/uhdlib/experts/expert_factory.hpp
@@ -0,0 +1,327 @@
+//
+// Copyright 2016 Ettus Research
+// Copyright 2018 Ettus Research, a National Instruments Company
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#ifndef INCLUDED_UHD_EXPERTS_EXPERT_FACTORY_HPP
+#define INCLUDED_UHD_EXPERTS_EXPERT_FACTORY_HPP
+
+#include <uhdlib/experts/expert_container.hpp>
+#include <uhd/property_tree.hpp>
+#include <uhd/config.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/bind.hpp>
+#include <memory>
+
+namespace uhd { namespace experts {
+
+    /*!
+     * expert_factory is a friend of expert_container and
+     * handles all operations to create and change the structure of
+     * the an expert container.
+     * The expert_factory allocates storage for the nodes in the
+     * expert_container and passes allocated objects to the container
+     * using private APIs. The expert_container instance owns all
+     * data and workernodes and is responsible for releasing their
+     * storage on destruction.
+     *
+     */
+    class UHD_API expert_factory : public boost::noncopyable {
+    public:
+
+        /*!
+         * Creates an empty instance of expert_container with the
+         * specified name.
+         *
+         * \param name Name of the container
+         */
+        static expert_container::sptr create_container(
+            const std::string& name
+        );
+
+        /*!
+         * Add a data node to the expert graph.
+         *
+         * \param container A shared pointer to the container to add the node to
+         * \param name The name of the data node
+         * \param init_val The initial value of the data node
+         * \param mode The auto resolve mode
+         *
+         * Requirements for data_t
+         * - Must have a default constructor
+         * - Must have a copy constructor
+         * - Must have an assignment operator (=)
+         * - Must have an equality operator (==)
+         */
+        template<typename data_t>
+        inline static void add_data_node(
+            expert_container::sptr container,
+            const std::string& name,
+            const data_t& init_val,
+            const auto_resolve_mode_t mode = AUTO_RESOLVE_OFF
+        ) {
+            container->add_data_node(new data_node_t<data_t>(name, init_val), mode);
+        }
+
+        /*!
+         * Add a expert property to a property tree AND an expert graph
+         *
+         * \param container A shared pointer to the expert container to add the node to
+         * \param subtree A shared pointer to subtree to add the property to
+         * \param path The path of the property in the subtree
+         * \param name The name of the data node in the expert graph
+         * \param init_val The initial value of the data node
+         * \param mode The auto resolve mode
+         *
+         * Requirements for data_t
+         * - Must have a default constructor
+         * - Must have a copy constructor
+         * - Must have an assignment operator (=)
+         * - Must have an equality operator (==)
+         */
+        template<typename data_t>
+        inline static property<data_t>& add_prop_node(
+            expert_container::sptr container,
+            property_tree::sptr subtree,
+            const fs_path &path,
+            const std::string& name,
+            const data_t& init_val,
+            const auto_resolve_mode_t mode = AUTO_RESOLVE_OFF
+        ) {
+            property<data_t>& prop = subtree->create<data_t>(path, property_tree::MANUAL_COERCE);
+            data_node_t<data_t>* node_ptr =
+                new data_node_t<data_t>(name, init_val, &container->resolve_mutex());
+            prop.set(init_val);
+            prop.add_desired_subscriber(boost::bind(&data_node_t<data_t>::commit, node_ptr, _1));
+            prop.set_publisher(boost::bind(&data_node_t<data_t>::retrieve, node_ptr));
+            container->add_data_node(node_ptr, mode);
+            return prop;
+        }
+
+        /*!
+         * Add a expert property to a property tree AND an expert graph.
+         * The property is registered with the path as the identifier for
+         * both the property subtree and the expert container
+         *
+         * \param container A shared pointer to the expert container to add the node to
+         * \param subtree A shared pointer to subtree to add the property to
+         * \param path The path of the property in the subtree
+         * \param init_val The initial value of the data node
+         * \param mode The auto resolve mode
+         *
+         */
+        template<typename data_t>
+        inline static property<data_t>& add_prop_node(
+            expert_container::sptr container,
+            property_tree::sptr subtree,
+            const fs_path &path,
+            const data_t& init_val,
+            const auto_resolve_mode_t mode = AUTO_RESOLVE_OFF
+        ) {
+            return add_prop_node(container, subtree, path, path, init_val, mode);
+        }
+
+        /*!
+         * Add a dual expert property to a property tree AND an expert graph.
+         * A dual property is a desired and coerced value pair
+         *
+         * \param container A shared pointer to the expert container to add the node to
+         * \param subtree A shared pointer to subtree to add the property to
+         * \param path The path of the property in the subtree
+         * \param desired_name The name of the desired data node in the expert graph
+         * \param desired_name The name of the coerced data node in the expert graph
+         * \param init_val The initial value of both the data nodes
+         * \param mode The auto resolve mode
+         *
+         * Requirements for data_t
+         * - Must have a default constructor
+         * - Must have a copy constructor
+         * - Must have an assignment operator (=)
+         * - Must have an equality operator (==)
+         */
+        template<typename data_t>
+        inline static property<data_t>& add_dual_prop_node(
+            expert_container::sptr container,
+            property_tree::sptr subtree,
+            const fs_path &path,
+            const std::string& desired_name,
+            const std::string& coerced_name,
+            const data_t& init_val,
+            const auto_resolve_mode_t mode = AUTO_RESOLVE_OFF
+        ) {
+            bool auto_resolve_desired = (mode==AUTO_RESOLVE_ON_WRITE or mode==AUTO_RESOLVE_ON_READ_WRITE);
+            bool auto_resolve_coerced = (mode==AUTO_RESOLVE_ON_READ or mode==AUTO_RESOLVE_ON_READ_WRITE);
+
+            property<data_t>& prop = subtree->create<data_t>(path, property_tree::MANUAL_COERCE);
+            data_node_t<data_t>* desired_node_ptr =
+                new data_node_t<data_t>(desired_name, init_val, &container->resolve_mutex());
+            data_node_t<data_t>* coerced_node_ptr =
+                new data_node_t<data_t>(coerced_name, init_val, &container->resolve_mutex());
+            prop.set(init_val);
+            prop.set_coerced(init_val);
+            prop.add_desired_subscriber(boost::bind(&data_node_t<data_t>::commit, desired_node_ptr, _1));
+            prop.set_publisher(boost::bind(&data_node_t<data_t>::retrieve, coerced_node_ptr));
+
+            container->add_data_node(desired_node_ptr,
+                auto_resolve_desired ? AUTO_RESOLVE_ON_WRITE : AUTO_RESOLVE_OFF);
+            container->add_data_node(coerced_node_ptr,
+                auto_resolve_coerced ? AUTO_RESOLVE_ON_READ : AUTO_RESOLVE_OFF);
+            return prop;
+        }
+
+        /*!
+         * Add a dual expert property to a property tree AND an expert graph.
+         * A dual property is a desired and coerced value pair
+         * The property is registered with path/desired as the desired node
+         * name and path/coerced as the coerced node name
+         *
+         * \param container A shared pointer to the expert container to add the node to
+         * \param subtree A shared pointer to subtree to add the property to
+         * \param path The path of the property in the subtree
+         * \param init_val The initial value of both the data nodes
+         * \param mode The auto resolve mode
+         *
+         */
+        template<typename data_t>
+        inline static property<data_t>& add_dual_prop_node(
+            expert_container::sptr container,
+            property_tree::sptr subtree,
+            const fs_path &path,
+            const data_t& init_val,
+            const auto_resolve_mode_t mode = AUTO_RESOLVE_OFF
+        ) {
+            return add_dual_prop_node(container, subtree, path, path + "/desired", path + "/coerced", init_val, mode);
+        }
+
+        /*!
+         * Add a worker node to the expert graph.
+         * The expert_container owns and manages storage for the worker
+         *
+         * \tparam worker_t Data type of the worker class
+         *
+         * \param container A shared pointer to the container to add the node to
+         *
+         */
+        template<typename worker_t>
+        inline static void add_worker_node(
+            expert_container::sptr container
+        ) {
+            container->add_worker(new worker_t());
+        }
+
+        /*!
+         * Add a worker node to the expert graph.
+         * The expert_container owns and manages storage for the worker
+         *
+         * \tparam worker_t Data type of the worker class
+         * \tparam arg1_t Data type of the first argument to the constructor
+         * \tparam ...
+         * \tparam argN_t Data type of the Nth argument to the constructor
+         *
+         * \param container A shared pointer to the container to add the node to
+         * \param arg1 First arg to ctor
+         * \param ...
+         * \param argN Nth arg to ctor
+         *
+         */
+        template<typename worker_t, typename arg1_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1
+        ) {
+            container->add_worker(new worker_t(arg1));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2
+        ) {
+            container->add_worker(new worker_t(arg1, arg2));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t, typename arg3_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2,
+            arg3_t const & arg3
+        ) {
+            container->add_worker(new worker_t(arg1, arg2, arg3));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t, typename arg3_t, typename arg4_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2,
+            arg3_t const & arg3,
+            arg4_t const & arg4
+        ) {
+            container->add_worker(new worker_t(arg1, arg2, arg3, arg4));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t, typename arg3_t, typename arg4_t,
+                                    typename arg5_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2,
+            arg3_t const & arg3,
+            arg4_t const & arg4,
+            arg5_t const & arg5
+        ) {
+            container->add_worker(new worker_t(arg1, arg2, arg3, arg4, arg5));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t, typename arg3_t, typename arg4_t,
+                                    typename arg5_t, typename arg6_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2,
+            arg3_t const & arg3,
+            arg4_t const & arg4,
+            arg5_t const & arg5,
+            arg6_t const & arg6
+        ) {
+            container->add_worker(new worker_t(arg1, arg2, arg3, arg4, arg5, arg6));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t, typename arg3_t, typename arg4_t,
+                                    typename arg5_t, typename arg6_t, typename arg7_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2,
+            arg3_t const & arg3,
+            arg4_t const & arg4,
+            arg5_t const & arg5,
+            arg6_t const & arg6,
+            arg7_t const & arg7
+        ) {
+            container->add_worker(new worker_t(arg1, arg2, arg3, arg4, arg5, arg6, arg7));
+        }
+
+        template<typename worker_t, typename arg1_t, typename arg2_t, typename arg3_t, typename arg4_t,
+                                    typename arg5_t, typename arg6_t, typename arg7_t, typename arg8_t>
+        inline static void add_worker_node(
+            expert_container::sptr container,
+            arg1_t const & arg1,
+            arg2_t const & arg2,
+            arg3_t const & arg3,
+            arg4_t const & arg4,
+            arg5_t const & arg5,
+            arg6_t const & arg6,
+            arg7_t const & arg7,
+            arg7_t const & arg8
+        ) {
+            container->add_worker(new worker_t(arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8));
+        }
+    };
+}}
+
+#endif /* INCLUDED_UHD_EXPERTS_EXPERT_FACTORY_HPP */
diff --git a/host/lib/include/uhdlib/experts/expert_nodes.hpp b/host/lib/include/uhdlib/experts/expert_nodes.hpp
new file mode 100644
index 000000000..697ca19c3
--- /dev/null
+++ b/host/lib/include/uhdlib/experts/expert_nodes.hpp
@@ -0,0 +1,472 @@
+//
+// Copyright 2016 Ettus Research
+// Copyright 2018 Ettus Research, a National Instruments Company
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+
+#ifndef INCLUDED_UHD_EXPERTS_EXPERT_NODES_HPP
+#define INCLUDED_UHD_EXPERTS_EXPERT_NODES_HPP
+
+#include <uhd/config.hpp>
+#include <uhd/exception.hpp>
+#include <uhd/utils/dirty_tracked.hpp>
+#include <uhd/types/time_spec.hpp>
+#include <boost/function.hpp>
+#include <boost/thread/recursive_mutex.hpp>
+#include <boost/thread.hpp>
+#include <boost/units/detail/utility.hpp>
+#include <memory>
+#include <list>
+#include <stdint.h>
+
+namespace uhd { namespace experts {
+
+    enum node_class_t  { CLASS_WORKER, CLASS_DATA, CLASS_PROPERTY };
+    enum node_access_t { ACCESS_READER, ACCESS_WRITER };
+    enum node_author_t { AUTHOR_NONE, AUTHOR_USER, AUTHOR_EXPERT };
+
+    /*!---------------------------------------------------------
+     * class dag_vertex_t
+     *
+     * This serves as the base class for all nodes in the expert
+     * graph. Data nodes and workers are derived from this class.
+     * ---------------------------------------------------------
+     */
+    class dag_vertex_t : private boost::noncopyable {
+    public:
+        typedef boost::function<void(std::string)> callback_func_t;
+
+        virtual ~dag_vertex_t() {}
+
+        // Getters for basic info about the node
+        inline node_class_t get_class() const {
+            return _class;
+        }
+
+        inline const std::string& get_name() const {
+            return _name;
+        }
+
+        virtual const std::string& get_dtype() const = 0;
+
+        virtual std::string to_string() const = 0;
+
+        // Graph resolution specific
+        virtual bool is_dirty() const = 0;
+        virtual void mark_clean() = 0;
+        virtual void resolve() = 0;
+
+        // External callbacks
+        virtual void set_write_callback(const callback_func_t& func) = 0;
+        virtual bool has_write_callback() const = 0;
+        virtual void clear_write_callback() = 0;
+        virtual void set_read_callback(const callback_func_t& func) = 0;
+        virtual bool has_read_callback() const = 0;
+        virtual void clear_read_callback() = 0;
+
+    protected:
+        dag_vertex_t(const node_class_t c, const std::string& n):
+            _class(c), _name(n) {}
+
+    private:
+        const node_class_t  _class;
+        const std::string   _name;
+    };
+
+    class data_node_printer {
+    public:
+        //Generic implementation
+        template<typename data_t>
+        static std::string print(const data_t& val) {
+            std::ostringstream os;
+            os << val;
+            return os.str();
+        }
+
+        static std::string print(const uint8_t& val) {
+            std::ostringstream os;
+            os << int(val);
+            return os.str();
+        }
+
+        static std::string print(const time_spec_t time) {
+            std::ostringstream os;
+            os << time.get_real_secs();
+            return os.str();
+        }
+    };
+
+    /*!---------------------------------------------------------
+     * class data_node_t
+     *
+     * The data node class hold a passive piece of data in the
+     * expert graph. A data node is clean if its underlying data
+     * is clean. Access to the underlying data is provided using
+     * two methods:
+     * 1. Special accessor classes (for R/W enforcement)
+     * 2. External clients (via commit and retrieve). This access
+     *    is protected by the callback mutex.
+     *
+     * Requirements for data_t
+     * - Must have a default constructor
+     * - Must have a copy constructor
+     * - Must have an assignment operator (=)
+     * - Must have an equality operator (==)
+     * ---------------------------------------------------------
+     */
+    template<typename data_t>
+    class data_node_t : public dag_vertex_t {
+    public:
+        // A data_node_t instance can have a type of CLASS_DATA or CLASS_PROPERTY
+        // In general a data node is a property if it can be accessed and modified
+        // from the outside world (of experts) using read and write callbacks. We
+        // assume that if a callback mutex is passed into the data node that it will
+        // be accessed from the outside and tag the data node as a PROPERTY.
+        data_node_t(const std::string& name, boost::recursive_mutex* mutex = NULL) :
+            dag_vertex_t(mutex?CLASS_PROPERTY:CLASS_DATA, name), _callback_mutex(mutex), _data(), _author(AUTHOR_NONE) {}
+
+        data_node_t(const std::string& name, const data_t& value, boost::recursive_mutex* mutex = NULL) :
+            dag_vertex_t(mutex?CLASS_PROPERTY:CLASS_DATA, name), _callback_mutex(mutex), _data(value), _author(AUTHOR_NONE) {}
+
+        // Basic info
+        virtual const std::string& get_dtype() const {
+            static const std::string dtype(
+                boost::units::detail::demangle(typeid(data_t).name()));
+            return dtype;
+        }
+
+        virtual std::string to_string() const {
+            return data_node_printer::print(get());
+        }
+
+        inline node_author_t get_author() const {
+            return _author;
+        }
+
+        // Graph resolution specific
+        virtual bool is_dirty() const {
+            return _data.is_dirty();
+        }
+
+        virtual void mark_clean() {
+            _data.mark_clean();
+        }
+
+        void resolve() {
+            //NOP
+        }
+
+        // Data node specific setters and getters (for the framework)
+        void set(const data_t& value) {
+            _data = value;
+            _author = AUTHOR_EXPERT;
+        }
+
+        const data_t& get() const {
+            return _data;
+        }
+
+        // Data node specific setters and getters (for external entities)
+        void commit(const data_t& value) {
+            if (_callback_mutex == NULL) throw uhd::assertion_error("node " + get_name() + " is missing the callback mutex");
+            boost::lock_guard<boost::recursive_mutex> lock(*_callback_mutex);
+            set(value);
+            _author = AUTHOR_USER;
+            if (is_dirty() and has_write_callback()) {
+                _wr_callback(std::string(get_name()));  //Put the name on the stack before calling
+            }
+        }
+
+        const data_t retrieve() const {
+            if (_callback_mutex == NULL) throw uhd::assertion_error("node " + get_name() + " is missing the callback mutex");
+            boost::lock_guard<boost::recursive_mutex> lock(*_callback_mutex);
+            if (has_read_callback()) {
+                _rd_callback(std::string(get_name()));
+            }
+            return get();
+        }
+
+    private:
+        // External callbacks
+        virtual void set_write_callback(const callback_func_t& func) {
+            _wr_callback = func;
+        }
+
+        virtual bool has_write_callback() const {
+            return not _wr_callback.empty();
+        }
+
+        virtual void clear_write_callback() {
+            _wr_callback.clear();
+        }
+
+        virtual void set_read_callback(const callback_func_t& func) {
+            _rd_callback = func;
+        }
+
+        virtual bool has_read_callback() const {
+            return not _rd_callback.empty();
+        }
+
+        virtual void clear_read_callback() {
+            _rd_callback.clear();
+        }
+
+        boost::recursive_mutex* _callback_mutex;
+        callback_func_t         _rd_callback;
+        callback_func_t         _wr_callback;
+        dirty_tracked<data_t>   _data;
+        node_author_t           _author;
+    };
+
+    /*!---------------------------------------------------------
+     * class node_retriever_t
+     *
+     * Node storage is managed by a framework class so we need
+     * and interface to find and retrieve data nodes to associate
+     * with accessors.
+     * ---------------------------------------------------------
+     */
+    class node_retriever_t {
+    public:
+        virtual ~node_retriever_t() {}
+        virtual const dag_vertex_t& lookup(const std::string& name) const = 0;
+    private:
+        friend class data_accessor_t;
+        virtual dag_vertex_t& retrieve(const std::string& name) const = 0;
+    };
+
+    /*!---------------------------------------------------------
+     * class data_accessor_t
+     *
+     * Accessors provide protected access to data nodes and help
+     * establish dependency relationships.
+     * ---------------------------------------------------------
+     */
+    class data_accessor_t {
+    public:
+        virtual ~data_accessor_t() {}
+
+        virtual bool is_reader() const = 0;
+        virtual bool is_writer() const = 0;
+        virtual dag_vertex_t& node() const = 0;
+    protected:
+        data_accessor_t(const node_retriever_t& r, const std::string& n):
+            _vertex(r.retrieve(n)) {}
+        dag_vertex_t& _vertex;
+    };
+
+    template<typename data_t>
+    class data_accessor_base : public data_accessor_t {
+    public:
+        virtual ~data_accessor_base() {}
+
+        virtual bool is_reader() const {
+            return _access == ACCESS_READER;
+        }
+
+        virtual bool is_writer() const {
+            return _access == ACCESS_WRITER;
+        }
+
+        inline bool is_dirty() const {
+            return _datanode->is_dirty();
+        }
+
+        inline node_class_t get_class() const {
+            return _datanode->get_class();
+        }
+
+        inline node_author_t get_author() const {
+            return _datanode->get_author();
+        }
+
+    protected:
+        data_accessor_base(
+            const node_retriever_t& r, const std::string& n, const node_access_t a) :
+                data_accessor_t(r, n), _datanode(NULL), _access(a)
+        {
+            _datanode = dynamic_cast< data_node_t<data_t>* >(&node());
+            if (_datanode == NULL) {
+                throw uhd::type_error("Expected data type for node " + n +
+                                      " was " + boost::units::detail::demangle(typeid(data_t).name()) +
+                                      " but got " + node().get_dtype());
+            }
+        }
+
+        data_node_t<data_t>*    _datanode;
+        const node_access_t     _access;
+
+    private:
+        virtual dag_vertex_t& node() const {
+            return _vertex;
+        }
+    };
+
+    /*!---------------------------------------------------------
+     * class data_reader_t
+     *
+     * Accessor to read the value of a data node and to establish
+     * a data node => worker node dependency
+     * ---------------------------------------------------------
+     */
+    template<typename data_t>
+    class data_reader_t : public data_accessor_base<data_t> {
+    public:
+        data_reader_t(const node_retriever_t& retriever, const std::string& node) :
+            data_accessor_base<data_t>(
+                retriever, node, ACCESS_READER) {}
+
+        inline const data_t& get() const {
+            return data_accessor_base<data_t>::_datanode->get();
+        }
+
+        inline operator const data_t&() const {
+            return get();
+        }
+
+        inline bool operator==(const data_t& rhs) {
+            return get() == rhs;
+        }
+
+        inline bool operator!=(const data_t& rhs) {
+            return !(get() == rhs);
+        }
+    };
+
+    /*!---------------------------------------------------------
+     * class data_reader_t
+     *
+     * Accessor to read and write the value of a data node and
+     * to establish a worker node => data node dependency
+     * ---------------------------------------------------------
+     */
+    template<typename data_t>
+    class data_writer_t : public data_accessor_base<data_t> {
+    public:
+        data_writer_t(const node_retriever_t& retriever, const std::string& node) :
+            data_accessor_base<data_t>(
+                retriever, node, ACCESS_WRITER) {}
+
+        inline const data_t& get() const {
+            return data_accessor_base<data_t>::_datanode->get();
+        }
+
+        inline operator const data_t&() const {
+            return get();
+        }
+
+        inline bool operator==(const data_t& rhs) {
+            return get() == rhs;
+        }
+
+        inline bool operator!=(const data_t& rhs) {
+            return !(get() == rhs);
+        }
+
+        inline void set(const data_t& value) {
+            data_accessor_base<data_t>::_datanode->set(value);
+        }
+
+        inline data_writer_t<data_t>& operator=(const data_t& value) {
+            set(value);
+            return *this;
+        }
+
+        inline data_writer_t<data_t>& operator=(const data_writer_t<data_t>& value) {
+            set(value.get());
+            return *this;
+        }
+};
+
+    /*!---------------------------------------------------------
+     * class worker_node_t
+     *
+     * A node class to implement a function that consumes
+     * zero or more input data nodes and emits zero or more output
+     * data nodes. The worker can also operate on other non-expert
+     * interfaces because worker_node_t is abstract and the client
+     * is required to implement the "resolve" method in a subclass.
+     * ---------------------------------------------------------
+     */
+    class worker_node_t : public dag_vertex_t {
+    public:
+        worker_node_t(const std::string& name) :
+            dag_vertex_t(CLASS_WORKER, name) {}
+
+        // Worker node specific
+        std::list<std::string> get_inputs() const {
+            std::list<std::string> retval;
+            for(data_accessor_t* acc:  _inputs) {
+                retval.push_back(acc->node().get_name());
+            }
+            return retval;
+        }
+
+        std::list<std::string> get_outputs() const {
+            std::list<std::string> retval;
+            for(data_accessor_t* acc:  _outputs) {
+                retval.push_back(acc->node().get_name());
+            }
+            return retval;
+        }
+
+    protected:
+        // This function is used to bind data accessors
+        // to this worker. Accessors can be read/write
+        // and the binding will ensure proper dependency
+        // handling.
+        void bind_accessor(data_accessor_t& accessor) {
+            if (accessor.is_reader()) {
+                _inputs.push_back(&accessor);
+            } else if (accessor.is_writer()) {
+                _outputs.push_back(&accessor);
+            } else {
+                throw uhd::assertion_error("Invalid accessor type");
+            }
+        }
+
+    private:
+        // Graph resolution specific
+        virtual bool is_dirty() const {
+            bool inputs_dirty = false;
+            for(data_accessor_t* acc:  _inputs) {
+                inputs_dirty |= acc->node().is_dirty();
+            }
+            return inputs_dirty;
+        }
+
+        virtual void mark_clean() {
+            for(data_accessor_t* acc:  _inputs) {
+                acc->node().mark_clean();
+            }
+        }
+
+        virtual void resolve() = 0;
+
+        // Basic type info
+        virtual const std::string& get_dtype() const {
+            static const std::string dtype = "<worker>";
+            return dtype;
+        }
+
+        virtual std::string to_string() const {
+            return "<worker>";
+        }
+
+        // Workers don't have callbacks so implement stubs
+        virtual void set_write_callback(const callback_func_t&) {}
+        virtual bool has_write_callback() const { return false; }
+        virtual void clear_write_callback() {}
+        virtual void set_read_callback(const callback_func_t&) {}
+        virtual bool has_read_callback() const { return false; }
+        virtual void clear_read_callback() {}
+
+        std::list<data_accessor_t*> _inputs;
+        std::list<data_accessor_t*> _outputs;
+    };
+
+}}
+
+#endif /* INCLUDED_UHD_EXPERTS_EXPERT_NODE_HPP */