1 |
/*************************************************************************** |
2 |
* * |
3 |
* LinuxSampler - modular, streaming capable sampler * |
4 |
* * |
5 |
* Copyright (C) 2003, 2004 by Benno Senoner and Christian Schoenebeck * |
6 |
* * |
7 |
* This program is free software; you can redistribute it and/or modify * |
8 |
* it under the terms of the GNU General Public License as published by * |
9 |
* the Free Software Foundation; either version 2 of the License, or * |
10 |
* (at your option) any later version. * |
11 |
* * |
12 |
* This program is distributed in the hope that it will be useful, * |
13 |
* but WITHOUT ANY WARRANTY; without even the implied warranty of * |
14 |
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
15 |
* GNU General Public License for more details. * |
16 |
* * |
17 |
* You should have received a copy of the GNU General Public License * |
18 |
* along with this program; if not, write to the Free Software * |
19 |
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, * |
20 |
* MA 02111-1307 USA * |
21 |
***************************************************************************/ |
22 |
|
23 |
#ifndef __RESOURCE_MANAGER__ |
24 |
#define __RESOURCE_MANAGER__ |
25 |
|
26 |
#include <set> |
27 |
#include <map> |
28 |
|
29 |
/** |
30 |
* Interface class for consumer classes which use a resource managed |
31 |
* by the ResourceManager class. |
32 |
*/ |
33 |
template<class T_res> |
34 |
class ResourceConsumer { |
35 |
public: |
36 |
/** |
37 |
* Will be called by the ResourceManager to inform the |
38 |
* consumer that a resource currently used by him is going |
39 |
* to be updated. The consumer can then react by stopping |
40 |
* usage until resource is updated. The ResourceManager will |
41 |
* not update the resource until this method returns. This |
42 |
* method needs to be implemented by the consumer. |
43 |
* |
44 |
* @param pResource - resource going to be updated |
45 |
* @param pUpdateArg - pointer the consumer might use to store |
46 |
* informations he might need when update |
47 |
* process was completed |
48 |
*/ |
49 |
virtual void ResourceToBeUpdated(T_res* pResource, void*& pUpdateArg) = 0; |
50 |
|
51 |
/** |
52 |
* Will be called by the ResourceManager to inform the |
53 |
* consumer that resource update was completed. This method |
54 |
* needs to be implemented by the consumer. |
55 |
* |
56 |
* @param pOldResource - (now invalid) pointer to the old |
57 |
* resource |
58 |
* @param pNewResource - (valid) pointer to the updated |
59 |
* resource |
60 |
* @param pUpdateArg - pointer the consumer might have used when |
61 |
* ResourceToBeUpdated() was called |
62 |
*/ |
63 |
virtual void ResourceUpdated(T_res* pOldResource, T_res* pNewResource, void* pUpdateArg) = 0; |
64 |
}; |
65 |
|
66 |
/** |
67 |
* Abstract base class for sharing resources between multiple consumers. |
68 |
* A consumer can borrow a resource from the ResourceManager, if the |
69 |
* resource doesn't exist yet it will be created. Other consumers will |
70 |
* just be given the same pointer to the resource then. When all consumers |
71 |
* gave back their pointer to the resource, the resource will be destroyed. |
72 |
* Descendants of this base class have to implement the (protected) |
73 |
* Create() and Destroy() methods to create and destroy a resource. |
74 |
*/ |
75 |
template<class T_key, class T_res> |
76 |
class ResourceManager { |
77 |
private: |
78 |
typedef std::set<ResourceConsumer<T_res>*> ConsumerSet; |
79 |
struct resource_entry_t { |
80 |
T_key key; |
81 |
T_res* resource; ///< pointer to the resource |
82 |
ConsumerSet consumers; ///< list of all consumers who currently use the resource |
83 |
void* arg; ///< optional pointer the descendant might use to store informations about the resource |
84 |
}; |
85 |
typedef std::map<T_key, resource_entry_t> ResourceMap; |
86 |
ResourceMap ResourceEntries; |
87 |
|
88 |
public: |
89 |
virtual ~ResourceManager() {} |
90 |
/** |
91 |
* Borrow a resource identified by \a Key. The ResourceManager will |
92 |
* mark the resource as in usage by the consumer given with |
93 |
* \a pConsumer. If the Resource doesn't exist yet it will be |
94 |
* created. |
95 |
* |
96 |
* @param Key - resource identifier |
97 |
* @param pConsumer - identifier of the consumer who borrows it |
98 |
* @returns pointer to resource |
99 |
*/ |
100 |
T_res* Borrow(T_key Key, ResourceConsumer<T_res>* pConsumer) { |
101 |
typename ResourceMap::iterator iterEntry = ResourceEntries.find(Key); |
102 |
if (iterEntry == ResourceEntries.end()) { |
103 |
resource_entry_t entry; |
104 |
entry.key = Key; |
105 |
entry.resource = Create(Key, pConsumer, entry.arg); |
106 |
entry.consumers.insert(pConsumer); |
107 |
OnBorrow(entry.resource, pConsumer, entry.arg); |
108 |
ResourceEntries[Key] = entry; |
109 |
return entry.resource; |
110 |
} |
111 |
resource_entry_t& entry = iterEntry->second; |
112 |
entry.consumers.insert(pConsumer); |
113 |
OnBorrow(entry.resource, pConsumer, entry.arg); |
114 |
return entry.resource; |
115 |
} |
116 |
|
117 |
/** |
118 |
* Give back a resource. This tells the ResourceManager that the |
119 |
* consumer given by \a pConsumer doesn't need the resource anymore. |
120 |
* If the resource is not needed by any consumer anymore then the |
121 |
* resource will be destroyed. |
122 |
* |
123 |
* @param pResource - pointer to resource |
124 |
* @param pConsumer - identifier of the consumer who borrowed the |
125 |
* resource |
126 |
*/ |
127 |
void HandBack(T_res* pResource, ResourceConsumer<T_res>* pConsumer) { |
128 |
typename ResourceMap::iterator iter = ResourceEntries.begin(); |
129 |
typename ResourceMap::iterator end = ResourceEntries.end(); |
130 |
for (; iter != end; iter++) { |
131 |
if (iter->second.resource == pResource) { |
132 |
resource_entry_t& entry = iter->second; |
133 |
entry.consumers.erase(pConsumer); |
134 |
if (entry.consumers.empty()) { |
135 |
ResourceEntries.erase(iter); |
136 |
Destroy(entry.resource, entry.arg); |
137 |
} |
138 |
return; |
139 |
} |
140 |
} |
141 |
} |
142 |
|
143 |
/** |
144 |
* Request update of a resource. |
145 |
* |
146 |
* @param pResource - resource to be updated |
147 |
* @param pConsumer - consumer who requested the update |
148 |
*/ |
149 |
void Update(T_res* pResource, ResourceConsumer<T_res>* pConsumer) { |
150 |
typename ResourceMap::iterator iter = ResourceEntries.begin(); |
151 |
typename ResourceMap::iterator end = ResourceEntries.end(); |
152 |
for (; iter != end; iter++) { |
153 |
if (iter->second.resource == pResource) { |
154 |
resource_entry_t& entry = iter->second; |
155 |
// inform all consumers about pending update |
156 |
std::map<ResourceConsumer<T_res>*,void*> updateargs; |
157 |
typename ConsumerSet::iterator iterCons = entry.consumers.begin(); |
158 |
typename ConsumerSet::iterator endCons = entry.consumers.end(); |
159 |
for (; iterCons != endCons; iterCons++) { |
160 |
if (*iterCons == pConsumer) continue; |
161 |
void* updatearg = NULL; |
162 |
(*iterCons)->ResourceToBeUpdated(entry.resource, updatearg); |
163 |
if (updatearg) updateargs[*iterCons] = updatearg; |
164 |
} |
165 |
// update resource |
166 |
T_res* pOldResource = entry.resource; |
167 |
Destroy(entry.resource, entry.arg); |
168 |
entry.resource = Create(entry.key, pConsumer, entry.arg); |
169 |
// inform all consumers about update completed |
170 |
iterCons = entry.consumers.begin(); |
171 |
endCons = entry.consumers.end(); |
172 |
for (; iterCons != endCons; iterCons++) { |
173 |
if (*iterCons == pConsumer) continue; |
174 |
typename std::map<ResourceConsumer<T_res>*,void*>::iterator iterArg = updateargs.find(*iterCons); |
175 |
void* updatearg = (iterArg != updateargs.end()) ? iterArg->second : NULL; |
176 |
(*iterCons)->ResourceUpdated(pOldResource, entry.resource, updatearg); |
177 |
} |
178 |
return; |
179 |
} |
180 |
} |
181 |
} |
182 |
|
183 |
protected: |
184 |
/** |
185 |
* Has to be implemented by the descendant to create (allocate) a |
186 |
* resource identified by \a Key. |
187 |
* |
188 |
* @param Key - identifier of the resource |
189 |
* @param pConsumer - identifier of the consumer who borrows the |
190 |
* resource |
191 |
* @param pArg - pointer the descendant can use to store |
192 |
* informations he might need for destruction of |
193 |
* the resource |
194 |
* @returns pointer to new resource |
195 |
*/ |
196 |
virtual T_res* Create(T_key Key, ResourceConsumer<T_res>* pConsumer, void*& pArg) = 0; |
197 |
|
198 |
/** |
199 |
* Has to be implemented by the descendant to destroy (free) a |
200 |
* resource pointed by \a pResource. |
201 |
* |
202 |
* @param pResource - pointer to the resource |
203 |
* @param pArg - pointer the descendant might have used when |
204 |
* Create() was called to store informations |
205 |
* about the resource |
206 |
*/ |
207 |
virtual void Destroy(T_res* pResource, void* pArg) = 0; |
208 |
|
209 |
/** |
210 |
* Has to be implemented by the descendant to react when a consumer |
211 |
* borrows a resource (no matter if freshly created or an already |
212 |
* created one). Of course reacting is optional, but the descendant |
213 |
* at least has to provide a method with empty body. |
214 |
* |
215 |
* @param pResource - pointer to the resource |
216 |
* @param pConsumer - identifier of the consumer who borrows the |
217 |
* resource |
218 |
* @param pArg - pointer the descendant might have used when |
219 |
* Create() was called to store informations |
220 |
* about the resource, this information can be |
221 |
* updated by the descendant here |
222 |
*/ |
223 |
virtual void OnBorrow(T_res* pResource, ResourceConsumer<T_res>* pConsumer, void*& pArg) = 0; |
224 |
}; |
225 |
|
226 |
#endif // __RESOURCE_MANAGER__ |