267 lines
9.2 KiB
C++
267 lines
9.2 KiB
C++
/*
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COMMAND-REGISTRY.hpp - proc-Command object registration and storage management
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Copyright (C) Lumiera.org
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2009, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/** @file command-registry.hpp
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** Managing command definitions and the storage of individual command objects.
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** The CommandRegistry is an singleton object, accessible only at the implementation level
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** of control::Command (note: CommandImpl isn't tied to the registry). For the other parts
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** of the command system, it provides all "get me this command object"-services. Actually,
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** these can be decomposed into two distinct parts:
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** - allocation of CommandImpl frames and argument holders, which is delegated
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** to the TypedAllocationManager
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** - maintaining an index to find pre-built command definitions (prototypes)
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**
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** \par Services during command lifecycle
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** Each command starts out as command definition, accessed by client code through CommandDef.
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** While collecting the necessary parts of such a definition, there is just an empty (pending)
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** Command (smart-ptr frontend), which is already registered with the intended command-ID.
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** A lookup on this ID would still fail at this point, as the \link #queryIndex search function \endlink
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** treats missing and incomplete command definitions similar. When the definition is complete,
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** a CommandImpl frame is allocated, configured and used to activate the Command (smart-ptr frontend).
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**
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** Later on, client code is assumed to re-access the command by ID. It may bind arguments, which are
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** stored in the already allocated ArgumentHolder. (-->Ticket #269). As the Command frontend is a
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** smart-ptr, commands may be copied, stored away and passed on. When finally the ref-count of
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** a given definition goes to zero, de-allocation happens automatically. This can't happen for
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** a registered command definition though, as a Command instance is stored within the index
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** table, keeping the linked data alive. Thus, any registered commands will remain in memory
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** until de-registered explicitly, or until application shutdown.
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**
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** @see Command
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** @see ProcDispatcher
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**
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*/
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#ifndef CONTROL_COMMAND_REGISTRY_H
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#define CONTROL_COMMAND_REGISTRY_H
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//#include "pre.hpp"
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#include "lib/error.hpp"
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#include "lib/singleton.hpp"
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#include "lib/sync.hpp"
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#include "lib/format.hpp"
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#include "include/logging.h"
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#include "lib/util.hpp"
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#include "proc/control/command.hpp"
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#include "proc/control/command-signature.hpp"
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#include "proc/control/command-argument-holder.hpp"
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#include "lib/typed-allocation-manager.hpp"
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#include <boost/functional/hash.hpp>
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#include <boost/noncopyable.hpp>
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#include <tr1/unordered_map>
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#include <tr1/memory>
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#include <string>
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#include <map>
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namespace control {
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using boost::hash;
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using boost::noncopyable;
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using std::tr1::shared_ptr;
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using std::tr1::unordered_map;
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using lib::TypedAllocationManager;
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using util::getValue_or_default;
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using util::contains;
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using std::string;
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using std::map;
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/**
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* Helper for building a std::map with
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* Command* as keys. Defines the order
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* by the address of the Command's
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* implementation object.
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*/
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struct order_by_impl
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{
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bool
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operator() (const Command *pC1, const Command *pC2) const
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{
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return ( pC1 && pC2 && (*pC1 < *pC2));
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}
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};
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/**
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* Registry managing command implementation objects (Singleton).
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* Relies on TypedAllocationManager for pooled custom allocation (TODO: not implemented as of 9/09)
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* Registered command (definitions) are accessible by command ID;
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* as this mapping is bidirectional, it is also possible to find
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* out the ID for a given command.
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*/
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class CommandRegistry
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: public lib::Sync<>
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, noncopyable
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{
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// using a hashtable to implement the index
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typedef unordered_map<Symbol, Command, hash<Symbol> > CmdIndex;
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typedef map< const Command*, Symbol, order_by_impl> ReverseIndex;
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TypedAllocationManager allocator_;
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CmdIndex index_;
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ReverseIndex ridx_;
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public:
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static lib::Singleton<CommandRegistry> instance;
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~CommandRegistry()
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{
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INFO (command, "Shutting down Command system...");
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//////////////////////TICKET #295 : possibly remotely trigger Command mass suicide here....
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ridx_.clear();
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index_.clear();
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}
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/** register a command (Frontend) under the given ID
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* @return either the new command, or an already existing
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* command registered under the given ID */
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Command&
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track (Symbol cmdID, Command const& commandHandle)
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{
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Lock sync(this);
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Command& indexSlot (index_[cmdID]);
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if (!indexSlot)
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{
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indexSlot = commandHandle;
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ridx_[&indexSlot] = cmdID;
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}
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return indexSlot;
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}
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/** remove the given command registration.
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* @return \c true if actually removed an entry
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* @note existing command instances remain valid;
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* storage will be freed at zero use-count */
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bool
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remove (Symbol cmdID)
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{
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Lock sync(this);
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bool actually_remove = contains (index_,cmdID);
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if (actually_remove)
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{
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ridx_.erase(& index_[cmdID]);
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index_.erase(cmdID);
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}
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ENSURE (!contains (index_,cmdID));
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return actually_remove;
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}
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/** query the command index by ID
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* @return the registered command,
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* or an "invalid" token */
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Command
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queryIndex (Symbol cmdID)
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{
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Lock sync(this);
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return getValue_or_default (index_, cmdID, Command() );
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} //if not found
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/** search the command index for a definition
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* @param cmdInstance using the definition to look up
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* @return the ID used to register this definition
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* or \c NULL in case of an "anonymous" command */
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const char*
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findDefinition (Command const& cmdInstance) const
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{
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Lock sync(this);
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return getValue_or_default (ridx_, &cmdInstance, 0 );
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} //used as Key
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size_t
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index_size() const
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{
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return index_.size();
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}
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size_t
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instance_count() const
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{
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return allocator_.numSlots<CommandImpl>();
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}
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/** set up a new command implementation frame
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* @return shared-ptr owning a newly created CommandImpl, allocated
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* through the registry and wired internally to invoke
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* TypedAllocationManager#destroyElement for cleanup.
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*/
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template< typename SIG_OPER ///< signature of the command operation
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, typename SIG_CAPT ///< signature for capturing undo state
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, typename SIG_UNDO ///< signature to undo the command
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>
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shared_ptr<CommandImpl>
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newCommandImpl (function<SIG_OPER>& operFunctor
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,function<SIG_CAPT>& captFunctor
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,function<SIG_UNDO>& undoFunctor)
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{
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// derive the storage type necessary
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// to hold the command arguments and UNDO memento
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typedef typename UndoSignature<SIG_CAPT>::Memento Mem;
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typedef ArgumentHolder<SIG_OPER,Mem> Arguments;
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shared_ptr<Arguments> pArg (allocator_.create<Arguments>());
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return allocator_.create<CommandImpl> (pArg, operFunctor,captFunctor,undoFunctor);
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}
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/** create an allocation for holding a clone of the given CommandImpl data.
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* This is a tricky operation, as the CommandImpl after construction erases the
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* specific type information pertaining the ArgumentHolder. But this specific
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* type information is vital for determining the exact allocation size for
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* the clone ArgumentHolder. The only solution is to delegate the cloning
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* of the arguments down into the ArgumentHolder, passing a reference
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* to the memory manager for allocating the clone.
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*/
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shared_ptr<CommandImpl>
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createCloneImpl (CommandImpl const& refObject)
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{
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return allocator_.create<CommandImpl> (refObject, allocator_);
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}
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};
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} // namespace control
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#endif
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