src/common/ResourceManager.h

/***************************************************************************
 *                                                                         *
 *   LinuxSampler - modular, streaming capable sampler                     *
 *                                                                         *
 *   Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck   *
 *   Copyright (C) 2005, 2006 Christian Schoenebeck                        *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the Free Software           *
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston,                 *
 *   MA  02111-1307  USA                                                   *
 ***************************************************************************/

#ifndef __RESOURCE_MANAGER__
#define __RESOURCE_MANAGER__

#include <set>
#include <map>
#include <vector>

#include "Exception.h"

namespace LinuxSampler {

/** @brief Interface class for Resource Consumers.
 *
 * Interface class for consumer classes which use a resource managed
 * by the ResourceManager class. All classes which use the ResourceManager
 * to aquire resources have to derive from this interface class and
 * implement the abstract methods.
 */
template<class T_res>
class ResourceConsumer {
    public:
        /**
         * Will be called by the ResourceManager to inform the
         * consumer that a resource currently used by him is going
         * to be updated. The consumer can then react by stopping
         * usage until resource is updated. The ResourceManager will
         * not update the resource until this method returns. This
         * method needs to be implemented by the consumer.
         *
         * @param pResource  - resource going to be updated
         * @param pUpdateArg - pointer the consumer might use to store
         *                     informations he might need when update
         *                     process was completed
         */
        virtual void ResourceToBeUpdated(T_res* pResource, void*& pUpdateArg) = 0;

        /**
         * Will be called by the ResourceManager to inform the
         * consumer that resource update was completed. This method
         * needs to be implemented by the consumer.
         *
         * @param pOldResource - (now invalid) pointer to the old
         *                       resource
         * @param pNewResource - (valid) pointer to the updated
         *                       resource
         * @param pUpdateArg   - pointer the consumer might have used when
         *                       ResourceToBeUpdated() was called
         */
        virtual void ResourceUpdated(T_res* pOldResource, T_res* pNewResource, void* pUpdateArg) = 0;

        /**
         * Might be called by the ResourceManager periodically during an
         * update / creation of a resource to inform the consumer about the
         * current progress of that process. This method needs to be
         * implemented by the consumer.
         *
         * @param fProgress - current progress as value between 0.0 and 1.0
         */
        virtual void OnResourceProgress(float fProgress) = 0;
};

/** @brief Manager for sharing resources.
 *
 * Abstract base class for sharing resources between multiple consumers.
 * A consumer can borrow a resource from the ResourceManager, if the
 * resource doesn't exist yet it will be created. Other consumers will
 * just be given the same pointer to the resource then. When all consumers
 * gave back their pointer to the resource, the resource will (by default)
 * be destroyed.
 *
 * Descendants of this base class have to implement the (protected)
 * Create() and Destroy() methods to create and destroy a resource.
 *
 * Note: this template class is not thread safe, so if thread safety is
 * needed the descendant has to add synchronization methods on its own.
 */
template<class T_key, class T_res>
class ResourceManager {
    public:
        /**
         * Defines life-time strategy for resources.
         */
        enum mode_t {
            ON_DEMAND      = 0, ///< Create resource when needed, free it once not needed anymore (default behavior).
            ON_DEMAND_HOLD = 1, ///< Create resource when needed and keep it even if not needed anymore.
            PERSISTENT     = 2  ///< Immediately create resource and keep it.
        };

    private:
        typedef std::set<ResourceConsumer<T_res>*> ConsumerSet;
        struct resource_entry_t {
            T_key       key;
            T_res*      resource;  ///< pointer to the resource
            mode_t      mode;      ///< When should the resource be created? When should it be destroyed?
            ConsumerSet consumers; ///< list of all consumers who currently use the resource
            void*       lifearg;   ///< optional pointer the descendant might use to store informations about a created resource
            void*       entryarg;  ///< optional pointer the descendant might use to store informations about an entry
        };
        typedef std::map<T_key, resource_entry_t> ResourceMap;
        ResourceMap ResourceEntries;

    public:
        /**
         * Returns (the keys of) all current entries of this
         * ResourceManager instance.
         */
        std::vector<T_key> Entries() {
            std::vector<T_key> result;
            for (typename ResourceMap::iterator iter = ResourceEntries.begin();
                 iter != ResourceEntries.end(); iter++)
            {
                result.push_back(iter->first);
            }
            return result;
        }

        /**
         * Borrow a resource identified by \a Key. The ResourceManager will
         * mark the resource as in usage by the consumer given with
         * \a pConsumer. If the Resource doesn't exist yet it will be
         * created.
         *
         * @param Key       - resource identifier
         * @param pConsumer - identifier of the consumer who borrows it
         * @returns  pointer to resource
         */
        T_res* Borrow(T_key Key, ResourceConsumer<T_res>* pConsumer) {
            // search for an entry for this resource
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            if (iterEntry == ResourceEntries.end()) { // entry doesn't exist yet
                // already create an entry for the resource
                resource_entry_t entry;
                entry.key      = Key;
                entry.resource = NULL;
                entry.mode     = ON_DEMAND; // default mode
                entry.lifearg  = NULL;
                entry.entryarg = NULL;
                entry.consumers.insert(pConsumer);
                ResourceEntries[Key] = entry;
                try {
                    // actually create the resource
                    entry.resource = Create(Key, pConsumer, entry.lifearg);
                } catch (...) {
                    // creating the resource failed, so remove the entry
                    ResourceEntries.erase(Key);
                    // rethrow the same exception
                    throw;
                }
                // now update the entry with the created resource
                ResourceEntries[Key] = entry;
                OnBorrow(entry.resource, pConsumer, entry.lifearg);
                return entry.resource;
            } else { // entry already exists
                resource_entry_t& entry = iterEntry->second;
                if (!entry.resource) { // create resource if not created already
                    try {
                        entry.resource = Create(Key, pConsumer, entry.lifearg);
                    } catch (...) {
                        entry.resource = NULL;
                        throw; // rethrow the same exception
                    }
                }
                entry.consumers.insert(pConsumer);
                OnBorrow(entry.resource, pConsumer, entry.lifearg);
                return entry.resource;
            }
        }

        /**
         * Give back a resource. This tells the ResourceManager that the
         * consumer given by \a pConsumer doesn't need the resource anymore.
         * If the resource is not needed by any consumer anymore and the
         * resource has a life-time strategy of ON_DEMAND (which is the
         * default setting) then the resource will be destroyed.
         *
         * @param pResource - pointer to resource
         * @param pConsumer - identifier of the consumer who borrowed the
         *                    resource
         */
        void HandBack(T_res* pResource, ResourceConsumer<T_res>* pConsumer) {
            // search for the entry associated with the given resource
            typename ResourceMap::iterator iter = ResourceEntries.begin();
            typename ResourceMap::iterator end  = ResourceEntries.end();
            for (; iter != end; iter++) {
                if (iter->second.resource == pResource) { // found entry for resource
                    resource_entry_t& entry = iter->second;
                    entry.consumers.erase(pConsumer);
                    // remove entry if necessary
                    if (entry.mode == ON_DEMAND && !entry.entryarg && entry.consumers.empty()) {
                        T_res* resource = entry.resource;
                        void* arg       = entry.lifearg;
                        ResourceEntries.erase(iter);
                        // destroy resource if necessary
                        if (resource) Destroy(resource, arg);
                    }
                    return;
                }
            }
        }

        /**
         * Request update of a resource. All consumers will be informed
         * about the pending update of the resource so they can safely react
         * by stopping its usage first, then the resource will be recreated
         * and finally the consumers will be informed once the update was
         * completed, so they can continue to use the resource.
         *
         * @param pResource - resource to be updated
         * @param pConsumer - consumer who requested the update
         */
        void Update(T_res* pResource, ResourceConsumer<T_res>* pConsumer) {
            typename ResourceMap::iterator iter = ResourceEntries.begin();
            typename ResourceMap::iterator end  = ResourceEntries.end();
            for (; iter != end; iter++) {
                if (iter->second.resource == pResource) {
                    resource_entry_t& entry = iter->second;
                    // inform all consumers about pending update
                    std::map<ResourceConsumer<T_res>*,void*> updateargs;
                    typename ConsumerSet::iterator iterCons = entry.consumers.begin();
                    typename ConsumerSet::iterator endCons  = entry.consumers.end();
                    for (; iterCons != endCons; iterCons++) {
                        if (*iterCons == pConsumer) continue;
                        void* updatearg = NULL;
                        (*iterCons)->ResourceToBeUpdated(entry.resource, updatearg);
                        if (updatearg) updateargs[*iterCons] = updatearg;
                    }
                    // update resource
                    T_res* pOldResource = entry.resource;
                    Destroy(entry.resource, entry.lifearg);
                    entry.resource = Create(entry.key, pConsumer, entry.lifearg);
                    // inform all consumers about update completed
                    iterCons = entry.consumers.begin();
                    endCons  = entry.consumers.end();
                    for (; iterCons != endCons; iterCons++) {
                        if (*iterCons == pConsumer) continue;
                        typename std::map<ResourceConsumer<T_res>*,void*>::iterator iterArg = updateargs.find(*iterCons);
                        void* updatearg = (iterArg != updateargs.end()) ? iterArg->second : NULL;
                        (*iterCons)->ResourceUpdated(pOldResource, entry.resource, updatearg);
                    }
                    return;
                }
            }
        }

        /**
         * Returns the life-time strategy of the given resource.
         *
         * @param Key - ID of the resource
         */
        mode_t AvailabilityMode(T_key Key) {
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            if (iterEntry == ResourceEntries.end())
                return ON_DEMAND; // resource entry doesn't exist, so we return the default mode
            resource_entry_t& entry = iterEntry->second;
            return entry.mode;
        }

        /**
         * Change life-time strategy of the given resource. If a life-time
         * strategy of PERSISTENT was given and the resource was not created
         * yet, it will immediately be created and this method will block
         * until the resource creation was completed.
         *
         * @param Key - ID of the resource
         * @param Mode - life-time strategy of resource to be set
         * @throws Exception in case an invalid Mode was given
         */
        void SetAvailabilityMode(T_key Key, mode_t Mode) throw (Exception) {
            if (Mode != ON_DEMAND && Mode != ON_DEMAND_HOLD && Mode != PERSISTENT)
                throw Exception("ResourceManager::SetAvailabilityMode(): invalid mode");

            // search for an entry for this resource
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            resource_entry_t* pEntry = NULL;
            if (iterEntry == ResourceEntries.end()) { // resource entry doesn't exist
                if (Mode == ON_DEMAND) return; // we don't create an entry for the default value
                // create an entry for the resource
                pEntry = &ResourceEntries[Key];
                pEntry->key      = Key;
                pEntry->resource = NULL;
                pEntry->mode     = Mode;
                pEntry->lifearg  = NULL;
                pEntry->entryarg = NULL;
            } else { // resource entry exists
                pEntry = &iterEntry->second;
                // remove entry if necessary
                if (Mode == ON_DEMAND && !pEntry->entryarg && pEntry->consumers.empty()) {
                    T_res* resource = pEntry->resource;
                    void* arg       = pEntry->lifearg;
                    ResourceEntries.erase(iterEntry);
                    // destroy resource if necessary
                    if (resource) Destroy(resource, arg);
                    return; // done
                }
                pEntry->mode = Mode; // apply new mode
            }

            // already create the resource if necessary
            if (pEntry->mode == PERSISTENT && !pEntry->resource) {
                try {
                    // actually create the resource
                    pEntry->resource = Create(Key, NULL /*no consumer yet*/, pEntry->lifearg);
                } catch (...) {
                    // creating the resource failed, so skip it for now
                    pEntry->resource = NULL;
                    // rethrow the same exception
                    throw;
                }
            }
        }

        /**
         * Returns true in case the resource associated with \a Key is
         * currently created / "alive".
         *
         * @param Key - ID of resource
         */
        bool IsCreated(T_key Key) {
            return Resource(Key) != NULL;
        }

        /**
         * Returns custom data sticked to the given resource previously by
         * a SetCustomData() call.
         *
         * @param Key - ID of resource
         */
        void* CustomData(T_key Key) {
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            if (iterEntry == ResourceEntries.end()) return NULL; // resource entry doesn't exist, so we return the default mode
            resource_entry_t& entry = iterEntry->second;
            return entry.entryarg;
        }

        /**
         * This method can be used to stick custom data to an resource
         * entry. In case the custom data is not needed anymore, you should
         * call this method again and set \a pData to NULL, so the
         * ResourceManager might safe space by removing the respective
         * entry if not needed anymore.
         *
         * @param Key - ID of resource
         * @param pData - pointer to custom data, or NULL if not needed anymore
         */
        void SetCustomData(T_key Key, void* pData) {
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            if (pData) {
                if (iterEntry == ResourceEntries.end()) { // entry doesnt exist, so create one
                    resource_entry_t* pEntry = &ResourceEntries[Key];
                    pEntry->key      = Key;
                    pEntry->resource = NULL;
                    pEntry->mode     = ON_DEMAND;
                    pEntry->lifearg  = NULL;
                    pEntry->entryarg = pData; // set custom data
                } else { // entry exists, so just update its custom data
                    iterEntry->second.entryarg = pData;
                }
            } else { // !pData
                if (iterEntry == ResourceEntries.end()) return; // entry doesnt exist, so nothing to do
                // entry exists, remove it if necessary
                resource_entry_t* pEntry = &iterEntry->second;
                if (pEntry->mode == ON_DEMAND && pEntry->consumers.empty()) {
                    ResourceEntries.erase(iterEntry);
                } else iterEntry->second.entryarg = NULL;
            }
        }

        virtual ~ResourceManager() {} // due to C++'s nature we cannot destroy created resources here

    protected:
        /**
         * Has to be implemented by the descendant to create (allocate) a
         * resource identified by \a Key.
         *
         * @param Key       - identifier of the resource
         * @param pConsumer - identifier of the consumer who borrows the
         *                    resource
         * @param pArg      - pointer the descendant can use to store
         *                    informations he might need for destruction of
         *                    the resource
         * @returns  pointer to new resource
         */
        virtual T_res* Create(T_key Key, ResourceConsumer<T_res>* pConsumer, void*& pArg) = 0;

        /**
         * Has to be implemented by the descendant to destroy (free) a
         * resource pointed by \a pResource.
         *
         * @param pResource - pointer to the resource
         * @param pArg      - pointer the descendant might have used when
         *                    Create() was called to store informations
         *                    about the resource
         */
        virtual void Destroy(T_res* pResource, void* pArg) = 0;

        /**
         * Has to be implemented by the descendant to react when a consumer
         * borrows a resource (no matter if freshly created or an already
         * created one). Of course reacting is optional, but the descendant
         * at least has to provide a method with empty body.
         *
         * @param pResource - pointer to the resource
         * @param pConsumer - identifier of the consumer who borrows the
         *                    resource
         * @param pArg      - pointer the descendant might have used when
         *                    Create() was called to store informations
         *                    about the resource, this information can be
         *                    updated by the descendant here
         */
        virtual void OnBorrow(T_res* pResource, ResourceConsumer<T_res>* pConsumer, void*& pArg) = 0;

        /**
         * Dispatcher method which should be periodically called by the
         * descendant during update or creation of the resource associated
         * with \a Key. This method will inform all associated consumers
         * of the given resource about the current progress.
         *
         * @param Key       - unique identifier of the resource which is
         *                    currently creating or updating
         * @param fProgress - current progress of that creation / update
         *                    process as value between 0.0 and 1.0
         */
        void DispatchResourceProgressEvent(T_key Key, float fProgress) {
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            if (iterEntry != ResourceEntries.end()) {
                resource_entry_t& entry = iterEntry->second;
                // inform all consumers of that resource about current progress
                typename ConsumerSet::iterator iterCons = entry.consumers.begin();
                typename ConsumerSet::iterator endCons  = entry.consumers.end();
                for (; iterCons != endCons; iterCons++) {
                    (*iterCons)->OnResourceProgress(fProgress);
                }
            }
        }

        /**
         * Returns pointer to the resource associated with \a Key if
         * currently created / "alive", NULL otherwise. This method
         * should be taken with great care in multi-threaded scenarios,
         * since the returned resource might be destroyed by a concurrent
         * HandBack() call.
         *
         * @param Key - ID of resource
         */
        T_res* Resource(T_key Key) {
            typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
            return (iterEntry == ResourceEntries.end()) ? NULL : iterEntry->second.resource;
        }
};

} // namespace LinuxSampler

#endif // __RESOURCE_MANAGER__
1	/***************************************************************************
2	* *
3	* LinuxSampler - modular, streaming capable sampler *
4	* *
5	* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck *
6	* Copyright (C) 2005, 2006 Christian Schoenebeck *
7	* *
8	* This program is free software; you can redistribute it and/or modify *
9	* it under the terms of the GNU General Public License as published by *
10	* the Free Software Foundation; either version 2 of the License, or *
11	* (at your option) any later version. *
12	* *
13	* This program is distributed in the hope that it will be useful, *
14	* but WITHOUT ANY WARRANTY; without even the implied warranty of *
15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16	* GNU General Public License for more details. *
17	* *
18	* You should have received a copy of the GNU General Public License *
19	* along with this program; if not, write to the Free Software *
20	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, *
21	* MA 02111-1307 USA *
22	***************************************************************************/
23
24	#ifndef __RESOURCE_MANAGER__
25	#define __RESOURCE_MANAGER__
26
27	#include <set>
28	#include <map>
29	#include <vector>
30
31	#include "Exception.h"
32
33	namespace LinuxSampler {
34
35	/** @brief Interface class for Resource Consumers.
36	*
37	* Interface class for consumer classes which use a resource managed
38	* by the ResourceManager class. All classes which use the ResourceManager
39	* to aquire resources have to derive from this interface class and
40	* implement the abstract methods.
41	*/
42	template<class T_res>
43	class ResourceConsumer {
44	public:
45	/**
46	* Will be called by the ResourceManager to inform the
47	* consumer that a resource currently used by him is going
48	* to be updated. The consumer can then react by stopping
49	* usage until resource is updated. The ResourceManager will
50	* not update the resource until this method returns. This
51	* method needs to be implemented by the consumer.
52	*
53	* @param pResource - resource going to be updated
54	* @param pUpdateArg - pointer the consumer might use to store
55	* informations he might need when update
56	* process was completed
57	*/
58	virtual void ResourceToBeUpdated(T_res* pResource, void*& pUpdateArg) = 0;
59
60	/**
61	* Will be called by the ResourceManager to inform the
62	* consumer that resource update was completed. This method
63	* needs to be implemented by the consumer.
64	*
65	* @param pOldResource - (now invalid) pointer to the old
66	* resource
67	* @param pNewResource - (valid) pointer to the updated
68	* resource
69	* @param pUpdateArg - pointer the consumer might have used when
70	* ResourceToBeUpdated() was called
71	*/
72	virtual void ResourceUpdated(T_res* pOldResource, T_res* pNewResource, void* pUpdateArg) = 0;
73
74	/**
75	* Might be called by the ResourceManager periodically during an
76	* update / creation of a resource to inform the consumer about the
77	* current progress of that process. This method needs to be
78	* implemented by the consumer.
79	*
80	* @param fProgress - current progress as value between 0.0 and 1.0
81	*/
82	virtual void OnResourceProgress(float fProgress) = 0;
83	};
84
85	/** @brief Manager for sharing resources.
86	*
87	* Abstract base class for sharing resources between multiple consumers.
88	* A consumer can borrow a resource from the ResourceManager, if the
89	* resource doesn't exist yet it will be created. Other consumers will
90	* just be given the same pointer to the resource then. When all consumers
91	* gave back their pointer to the resource, the resource will (by default)
92	* be destroyed.
93	*
94	* Descendants of this base class have to implement the (protected)
95	* Create() and Destroy() methods to create and destroy a resource.
96	*
97	* Note: this template class is not thread safe, so if thread safety is
98	* needed the descendant has to add synchronization methods on its own.
99	*/
100	template<class T_key, class T_res>
101	class ResourceManager {
102	public:
103	/**
104	* Defines life-time strategy for resources.
105	*/
106	enum mode_t {
107	ON_DEMAND = 0, ///< Create resource when needed, free it once not needed anymore (default behavior).
108	ON_DEMAND_HOLD = 1, ///< Create resource when needed and keep it even if not needed anymore.
109	PERSISTENT = 2 ///< Immediately create resource and keep it.
110	};
111
112	private:
113	typedef std::set<ResourceConsumer<T_res>*> ConsumerSet;
114	struct resource_entry_t {
115	T_key key;
116	T_res* resource; ///< pointer to the resource
117	mode_t mode; ///< When should the resource be created? When should it be destroyed?
118	ConsumerSet consumers; ///< list of all consumers who currently use the resource
119	void* lifearg; ///< optional pointer the descendant might use to store informations about a created resource
120	void* entryarg; ///< optional pointer the descendant might use to store informations about an entry
121	};
122	typedef std::map<T_key, resource_entry_t> ResourceMap;
123	ResourceMap ResourceEntries;
124
125	public:
126	/**
127	* Returns (the keys of) all current entries of this
128	* ResourceManager instance.
129	*/
130	std::vector<T_key> Entries() {
131	std::vector<T_key> result;
132	for (typename ResourceMap::iterator iter = ResourceEntries.begin();
133	iter != ResourceEntries.end(); iter++)
134	{
135	result.push_back(iter->first);
136	}
137	return result;
138	}
139
140	/**
141	* Borrow a resource identified by \a Key. The ResourceManager will
142	* mark the resource as in usage by the consumer given with
143	* \a pConsumer. If the Resource doesn't exist yet it will be
144	* created.
145	*
146	* @param Key - resource identifier
147	* @param pConsumer - identifier of the consumer who borrows it
148	* @returns pointer to resource
149	*/
150	T_res* Borrow(T_key Key, ResourceConsumer<T_res>* pConsumer) {
151	// search for an entry for this resource
152	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
153	if (iterEntry == ResourceEntries.end()) { // entry doesn't exist yet
154	// already create an entry for the resource
155	resource_entry_t entry;
156	entry.key = Key;
157	entry.resource = NULL;
158	entry.mode = ON_DEMAND; // default mode
159	entry.lifearg = NULL;
160	entry.entryarg = NULL;
161	entry.consumers.insert(pConsumer);
162	ResourceEntries[Key] = entry;
163	try {
164	// actually create the resource
165	entry.resource = Create(Key, pConsumer, entry.lifearg);
166	} catch (...) {
167	// creating the resource failed, so remove the entry
168	ResourceEntries.erase(Key);
169	// rethrow the same exception
170	throw;
171	}
172	// now update the entry with the created resource
173	ResourceEntries[Key] = entry;
174	OnBorrow(entry.resource, pConsumer, entry.lifearg);
175	return entry.resource;
176	} else { // entry already exists
177	resource_entry_t& entry = iterEntry->second;
178	if (!entry.resource) { // create resource if not created already
179	try {
180	entry.resource = Create(Key, pConsumer, entry.lifearg);
181	} catch (...) {
182	entry.resource = NULL;
183	throw; // rethrow the same exception
184	}
185	}
186	entry.consumers.insert(pConsumer);
187	OnBorrow(entry.resource, pConsumer, entry.lifearg);
188	return entry.resource;
189	}
190	}
191
192	/**
193	* Give back a resource. This tells the ResourceManager that the
194	* consumer given by \a pConsumer doesn't need the resource anymore.
195	* If the resource is not needed by any consumer anymore and the
196	* resource has a life-time strategy of ON_DEMAND (which is the
197	* default setting) then the resource will be destroyed.
198	*
199	* @param pResource - pointer to resource
200	* @param pConsumer - identifier of the consumer who borrowed the
201	* resource
202	*/
203	void HandBack(T_res* pResource, ResourceConsumer<T_res>* pConsumer) {
204	// search for the entry associated with the given resource
205	typename ResourceMap::iterator iter = ResourceEntries.begin();
206	typename ResourceMap::iterator end = ResourceEntries.end();
207	for (; iter != end; iter++) {
208	if (iter->second.resource == pResource) { // found entry for resource
209	resource_entry_t& entry = iter->second;
210	entry.consumers.erase(pConsumer);
211	// remove entry if necessary
212	if (entry.mode == ON_DEMAND && !entry.entryarg && entry.consumers.empty()) {
213	T_res* resource = entry.resource;
214	void* arg = entry.lifearg;
215	ResourceEntries.erase(iter);
216	// destroy resource if necessary
217	if (resource) Destroy(resource, arg);
218	}
219	return;
220	}
221	}
222	}
223
224	/**
225	* Request update of a resource. All consumers will be informed
226	* about the pending update of the resource so they can safely react
227	* by stopping its usage first, then the resource will be recreated
228	* and finally the consumers will be informed once the update was
229	* completed, so they can continue to use the resource.
230	*
231	* @param pResource - resource to be updated
232	* @param pConsumer - consumer who requested the update
233	*/
234	void Update(T_res* pResource, ResourceConsumer<T_res>* pConsumer) {
235	typename ResourceMap::iterator iter = ResourceEntries.begin();
236	typename ResourceMap::iterator end = ResourceEntries.end();
237	for (; iter != end; iter++) {
238	if (iter->second.resource == pResource) {
239	resource_entry_t& entry = iter->second;
240	// inform all consumers about pending update
241	std::map<ResourceConsumer<T_res>,void> updateargs;
242	typename ConsumerSet::iterator iterCons = entry.consumers.begin();
243	typename ConsumerSet::iterator endCons = entry.consumers.end();
244	for (; iterCons != endCons; iterCons++) {
245	if (*iterCons == pConsumer) continue;
246	void* updatearg = NULL;
247	(*iterCons)->ResourceToBeUpdated(entry.resource, updatearg);
248	if (updatearg) updateargs[*iterCons] = updatearg;
249	}
250	// update resource
251	T_res* pOldResource = entry.resource;
252	Destroy(entry.resource, entry.lifearg);
253	entry.resource = Create(entry.key, pConsumer, entry.lifearg);
254	// inform all consumers about update completed
255	iterCons = entry.consumers.begin();
256	endCons = entry.consumers.end();
257	for (; iterCons != endCons; iterCons++) {
258	if (*iterCons == pConsumer) continue;
259	typename std::map<ResourceConsumer<T_res>,void>::iterator iterArg = updateargs.find(*iterCons);
260	void* updatearg = (iterArg != updateargs.end()) ? iterArg->second : NULL;
261	(*iterCons)->ResourceUpdated(pOldResource, entry.resource, updatearg);
262	}
263	return;
264	}
265	}
266	}
267
268	/**
269	* Returns the life-time strategy of the given resource.
270	*
271	* @param Key - ID of the resource
272	*/
273	mode_t AvailabilityMode(T_key Key) {
274	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
275	if (iterEntry == ResourceEntries.end())
276	return ON_DEMAND; // resource entry doesn't exist, so we return the default mode
277	resource_entry_t& entry = iterEntry->second;
278	return entry.mode;
279	}
280
281	/**
282	* Change life-time strategy of the given resource. If a life-time
283	* strategy of PERSISTENT was given and the resource was not created
284	* yet, it will immediately be created and this method will block
285	* until the resource creation was completed.
286	*
287	* @param Key - ID of the resource
288	* @param Mode - life-time strategy of resource to be set
289	* @throws Exception in case an invalid Mode was given
290	*/
291	void SetAvailabilityMode(T_key Key, mode_t Mode) throw (Exception) {
292	if (Mode != ON_DEMAND && Mode != ON_DEMAND_HOLD && Mode != PERSISTENT)
293	throw Exception("ResourceManager::SetAvailabilityMode(): invalid mode");
294
295	// search for an entry for this resource
296	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
297	resource_entry_t* pEntry = NULL;
298	if (iterEntry == ResourceEntries.end()) { // resource entry doesn't exist
299	if (Mode == ON_DEMAND) return; // we don't create an entry for the default value
300	// create an entry for the resource
301	pEntry = &ResourceEntries[Key];
302	pEntry->key = Key;
303	pEntry->resource = NULL;
304	pEntry->mode = Mode;
305	pEntry->lifearg = NULL;
306	pEntry->entryarg = NULL;
307	} else { // resource entry exists
308	pEntry = &iterEntry->second;
309	// remove entry if necessary
310	if (Mode == ON_DEMAND && !pEntry->entryarg && pEntry->consumers.empty()) {
311	T_res* resource = pEntry->resource;
312	void* arg = pEntry->lifearg;
313	ResourceEntries.erase(iterEntry);
314	// destroy resource if necessary
315	if (resource) Destroy(resource, arg);
316	return; // done
317	}
318	pEntry->mode = Mode; // apply new mode
319	}
320
321	// already create the resource if necessary
322	if (pEntry->mode == PERSISTENT && !pEntry->resource) {
323	try {
324	// actually create the resource
325	pEntry->resource = Create(Key, NULL /no consumer yet/, pEntry->lifearg);
326	} catch (...) {
327	// creating the resource failed, so skip it for now
328	pEntry->resource = NULL;
329	// rethrow the same exception
330	throw;
331	}
332	}
333	}
334
335	/**
336	* Returns true in case the resource associated with \a Key is
337	* currently created / "alive".
338	*
339	* @param Key - ID of resource
340	*/
341	bool IsCreated(T_key Key) {
342	return Resource(Key) != NULL;
343	}
344
345	/**
346	* Returns custom data sticked to the given resource previously by
347	* a SetCustomData() call.
348	*
349	* @param Key - ID of resource
350	*/
351	void* CustomData(T_key Key) {
352	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
353	if (iterEntry == ResourceEntries.end()) return NULL; // resource entry doesn't exist, so we return the default mode
354	resource_entry_t& entry = iterEntry->second;
355	return entry.entryarg;
356	}
357
358	/**
359	* This method can be used to stick custom data to an resource
360	* entry. In case the custom data is not needed anymore, you should
361	* call this method again and set \a pData to NULL, so the
362	* ResourceManager might safe space by removing the respective
363	* entry if not needed anymore.
364	*
365	* @param Key - ID of resource
366	* @param pData - pointer to custom data, or NULL if not needed anymore
367	*/
368	void SetCustomData(T_key Key, void* pData) {
369	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
370	if (pData) {
371	if (iterEntry == ResourceEntries.end()) { // entry doesnt exist, so create one
372	resource_entry_t* pEntry = &ResourceEntries[Key];
373	pEntry->key = Key;
374	pEntry->resource = NULL;
375	pEntry->mode = ON_DEMAND;
376	pEntry->lifearg = NULL;
377	pEntry->entryarg = pData; // set custom data
378	} else { // entry exists, so just update its custom data
379	iterEntry->second.entryarg = pData;
380	}
381	} else { // !pData
382	if (iterEntry == ResourceEntries.end()) return; // entry doesnt exist, so nothing to do
383	// entry exists, remove it if necessary
384	resource_entry_t* pEntry = &iterEntry->second;
385	if (pEntry->mode == ON_DEMAND && pEntry->consumers.empty()) {
386	ResourceEntries.erase(iterEntry);
387	} else iterEntry->second.entryarg = NULL;
388	}
389	}
390
391	virtual ~ResourceManager() {} // due to C++'s nature we cannot destroy created resources here
392
393	protected:
394	/**
395	* Has to be implemented by the descendant to create (allocate) a
396	* resource identified by \a Key.
397	*
398	* @param Key - identifier of the resource
399	* @param pConsumer - identifier of the consumer who borrows the
400	* resource
401	* @param pArg - pointer the descendant can use to store
402	* informations he might need for destruction of
403	* the resource
404	* @returns pointer to new resource
405	*/
406	virtual T_res* Create(T_key Key, ResourceConsumer<T_res>* pConsumer, void*& pArg) = 0;
407
408	/**
409	* Has to be implemented by the descendant to destroy (free) a
410	* resource pointed by \a pResource.
411	*
412	* @param pResource - pointer to the resource
413	* @param pArg - pointer the descendant might have used when
414	* Create() was called to store informations
415	* about the resource
416	*/
417	virtual void Destroy(T_res* pResource, void* pArg) = 0;
418
419	/**
420	* Has to be implemented by the descendant to react when a consumer
421	* borrows a resource (no matter if freshly created or an already
422	* created one). Of course reacting is optional, but the descendant
423	* at least has to provide a method with empty body.
424	*
425	* @param pResource - pointer to the resource
426	* @param pConsumer - identifier of the consumer who borrows the
427	* resource
428	* @param pArg - pointer the descendant might have used when
429	* Create() was called to store informations
430	* about the resource, this information can be
431	* updated by the descendant here
432	*/
433	virtual void OnBorrow(T_res* pResource, ResourceConsumer<T_res>* pConsumer, void*& pArg) = 0;
434
435	/**
436	* Dispatcher method which should be periodically called by the
437	* descendant during update or creation of the resource associated
438	* with \a Key. This method will inform all associated consumers
439	* of the given resource about the current progress.
440	*
441	* @param Key - unique identifier of the resource which is
442	* currently creating or updating
443	* @param fProgress - current progress of that creation / update
444	* process as value between 0.0 and 1.0
445	*/
446	void DispatchResourceProgressEvent(T_key Key, float fProgress) {
447	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
448	if (iterEntry != ResourceEntries.end()) {
449	resource_entry_t& entry = iterEntry->second;
450	// inform all consumers of that resource about current progress
451	typename ConsumerSet::iterator iterCons = entry.consumers.begin();
452	typename ConsumerSet::iterator endCons = entry.consumers.end();
453	for (; iterCons != endCons; iterCons++) {
454	(*iterCons)->OnResourceProgress(fProgress);
455	}
456	}
457	}
458
459	/**
460	* Returns pointer to the resource associated with \a Key if
461	* currently created / "alive", NULL otherwise. This method
462	* should be taken with great care in multi-threaded scenarios,
463	* since the returned resource might be destroyed by a concurrent
464	* HandBack() call.
465	*
466	* @param Key - ID of resource
467	*/
468	T_res* Resource(T_key Key) {
469	typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key);
470	return (iterEntry == ResourceEntries.end()) ? NULL : iterEntry->second.resource;
471	}
472	};
473
474	} // namespace LinuxSampler
475
476	#endif // __RESOURCE_MANAGER__