genode/repos/base/src/core/include/trace/policy_registry.h

/*
 * \brief  Registry containing tracing policy modules
 * \author Norman Feske
 * \date   2013-08-12
 */

/*
 * Copyright (C) 2013-2017 Genode Labs GmbH
 *
 * This file is part of the Genode OS framework, which is distributed
 * under the terms of the GNU Affero General Public License version 3.
 */

#ifndef _CORE__INCLUDE__TRACE__POLICY_REGISTRY_H_
#define _CORE__INCLUDE__TRACE__POLICY_REGISTRY_H_

/* Genode includes */
#include <base/lock.h>
#include <util/list.h>

namespace Genode { namespace Trace {
	class Policy_owner;
	class Policy;
	class Policy_registry;
} }


class Genode::Trace::Policy_owner : Interface { };


class Genode::Trace::Policy : public Genode::List<Genode::Trace::Policy>::Element
{
	friend class Policy_registry;

	private:

		Policy_owner  const &_owner;
		Allocator           &_md_alloc;
		Policy_id     const  _id;
		Dataspace_capability _ds;
		size_t        const  _size;

		/**
		 * Constructor
		 *
		 * \param md_alloc  allocator that holds the 'Policy' object
		 */
		Policy(Policy_owner const &owner, Policy_id const id,
		       Allocator &md_alloc, Dataspace_capability ds, size_t size)
		:
			_owner(owner), _md_alloc(md_alloc), _id(id), _ds(ds), _size(size)
		{ }

		Allocator &md_alloc() { return _md_alloc; }

		bool owned_by(Policy_owner const &owner) const
		{
			return &_owner == &owner;
		}

		bool has_id(Policy_id id) const { return id == _id; }

	public:

		Dataspace_capability dataspace() const { return _ds; }
		size_t               size()      const { return _size; }
};


/**
 * Global policy registry
 */
class Genode::Trace::Policy_registry
{

	private:

		Lock         _lock     { };
		List<Policy> _policies { };

		Policy &_unsynchronized_lookup(Policy_owner const &owner, Policy_id id)
		{
			for (Policy *p = _policies.first(); p; p = p->next())
				if (p->owned_by(owner) && p->has_id(id))
					return *p;

			throw Nonexistent_policy();
		}

		Policy *_any_policy_owned_by(Policy_owner const &owner)
		{
			for (Policy *p = _policies.first(); p; p = p->next())
				if (p->owned_by(owner))
					return p;

			return nullptr;
		}

	public:

		~Policy_registry()
		{
			Lock::Guard guard(_lock);

			while (Policy *p = _policies.first())
				_policies.remove(p);
		}

		void insert(Policy_owner const &owner, Policy_id const id,
		            Allocator &md_alloc, Dataspace_capability ds, size_t size)
		{
			Lock::Guard guard(_lock);

			Policy &policy = *new (&md_alloc) Policy(owner, id, md_alloc, ds, size);
			_policies.insert(&policy);
		}

		void remove(Policy_owner &owner, Policy_id id)
		{
			Lock::Guard guard(_lock);

			for (Policy *p = _policies.first(); p; ) {
				Policy *tmp = p;
				p = p->next();

				if (tmp->owned_by(owner) && tmp->has_id(id)) {
					_policies.remove(tmp);
					destroy(&tmp->md_alloc(), tmp);
				}
			}
		}

		void destroy_policies_owned_by(Policy_owner const &owner)
		{
			Lock::Guard guard(_lock);

			while (Policy *p = _any_policy_owned_by(owner)) {
				_policies.remove(p);
				destroy(&p->md_alloc(), p);
			}
		}

		Dataspace_capability dataspace(Policy_owner &owner, Policy_id id)
		{
			Lock::Guard guard(_lock);

			return _unsynchronized_lookup(owner, id).dataspace();
		}

		size_t size(Policy_owner &owner, Policy_id id)
		{
			Lock::Guard guard(_lock);

			return _unsynchronized_lookup(owner, id).size();
		}
};

#endif /* _CORE__INCLUDE__TRACE__POLICY_REGISTRY_H_ */