1 | /* -*- C++ -*- */ |
---|
2 | |
---|
3 | #ifndef _LOOSESLOTHEAP_H_ |
---|
4 | #define _LOOSESLOTHEAP_H_ |
---|
5 | |
---|
6 | #include <assert.h> |
---|
7 | |
---|
8 | #include "bigchunk.h" |
---|
9 | |
---|
10 | /* |
---|
11 | LooseSlotHeap: A "Loose" slot heap. |
---|
12 | |
---|
13 | malloc returns objects of size slotSize, allocated from the super heap |
---|
14 | in chunkSize units. |
---|
15 | |
---|
16 | free returns objects of size slotSize. |
---|
17 | |
---|
18 | When the slot heap is at least 1/emptyFraction empty, a |
---|
19 | chunk that is at least that empty is freed to the super heap. |
---|
20 | Note that the chunk's memory MAY NOT SAFELY be recycled in toto -- |
---|
21 | it must be parceled out using the chunk interface. |
---|
22 | |
---|
23 | The intent of this heap is to allow mostly-empty chunks to move up |
---|
24 | to a staging area (the super heap) where they may be reused by other |
---|
25 | "loose" slot heaps. |
---|
26 | |
---|
27 | */ |
---|
28 | |
---|
29 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
30 | class LooseSlotHeap { |
---|
31 | public: |
---|
32 | |
---|
33 | inline LooseSlotHeap (void); |
---|
34 | inline ~LooseSlotHeap (void); |
---|
35 | |
---|
36 | // Get a slotSize object. |
---|
37 | inline void * malloc (size_t sz); |
---|
38 | |
---|
39 | // Free a slotSize object. |
---|
40 | static inline void free (void * ptr); |
---|
41 | |
---|
42 | private: |
---|
43 | |
---|
44 | Super theHeap; |
---|
45 | |
---|
46 | typedef BigChunk<chunkSize, slotSize, LooseSlotHeap> chunkType; |
---|
47 | |
---|
48 | inline void localFree (void * ptr); |
---|
49 | |
---|
50 | void checkClassInvariant (void) { |
---|
51 | #ifndef NDEBUG |
---|
52 | assert (inUse >= 0); |
---|
53 | assert (inUse <= space); |
---|
54 | assert (lastIndex >= 0); |
---|
55 | assert (lastIndex <= emptyFraction); |
---|
56 | // Now check to make sure that inUse & space are correct. |
---|
57 | int localInUse = 0; |
---|
58 | int localSpace = 0; |
---|
59 | for (int i = 0; i < emptyFraction + 1; i++) { |
---|
60 | chunkType * ch = myChunks[i]; |
---|
61 | while (ch != NULL) { |
---|
62 | assert (ch->getHeap() == this); |
---|
63 | localInUse += ch->getNumSlotsInUse(); |
---|
64 | localSpace += ch->getNumSlots(); |
---|
65 | ch = ch->getNext(); |
---|
66 | } |
---|
67 | } |
---|
68 | assert (localSpace == space); |
---|
69 | assert (localInUse == inUse); |
---|
70 | #endif |
---|
71 | } |
---|
72 | |
---|
73 | // How full is this block? |
---|
74 | // 0 == empty to no more than 1/emptyFraction full. |
---|
75 | // emptyFraction == completely full. |
---|
76 | static inline int getFullness (chunkType * ch); |
---|
77 | |
---|
78 | // Move a chunk, if necessary, into the right list |
---|
79 | // based on its emptiness. |
---|
80 | // Returns the index of which list it is put or left in. |
---|
81 | inline int update (chunkType * ch, int prevIndex); |
---|
82 | |
---|
83 | // The array of chunks, "radix sorted" by emptiness. |
---|
84 | // completely empty chunks are in index 0. |
---|
85 | // completely full chunks are in index emptyFraction. |
---|
86 | chunkType * myChunks[emptyFraction + 1]; |
---|
87 | |
---|
88 | // The last index (from 0) in the above array that has a chunk. |
---|
89 | int lastIndex; |
---|
90 | |
---|
91 | // How much space is in use in all of the chunks. |
---|
92 | int inUse; |
---|
93 | |
---|
94 | // How much space there is (free or not) in all of the chunks. |
---|
95 | int space; |
---|
96 | }; |
---|
97 | |
---|
98 | |
---|
99 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
100 | LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::LooseSlotHeap (void) |
---|
101 | : space (0), |
---|
102 | inUse (0), |
---|
103 | lastIndex (emptyFraction - 1) |
---|
104 | { |
---|
105 | // Initialize the chunk pointers (all initially empty). |
---|
106 | for (int i = 0; i < emptyFraction + 1; i++) { |
---|
107 | myChunks[i] = NULL; |
---|
108 | } |
---|
109 | } |
---|
110 | |
---|
111 | |
---|
112 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
113 | LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::~LooseSlotHeap (void) |
---|
114 | { |
---|
115 | // Free every chunk. |
---|
116 | chunkType * ch, * tmp; |
---|
117 | for (int i = 0; i < emptyFraction + 1; i++) { |
---|
118 | ch = myChunks[i]; |
---|
119 | while (ch != NULL) { |
---|
120 | tmp = ch; |
---|
121 | ch = ch->getNext(); |
---|
122 | theHeap.free (tmp); |
---|
123 | } |
---|
124 | } |
---|
125 | } |
---|
126 | |
---|
127 | |
---|
128 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
129 | int LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::getFullness (chunkType * ch) |
---|
130 | { |
---|
131 | int fullness = (emptyFraction * ch->getNumSlotsInUse())/ch->getNumSlots(); |
---|
132 | //printf ("numslots avail = %d, num slots total = %d, fullness = %d\n", ch->getNumSlotsFree(), ch->getNumSlots(), fullness); |
---|
133 | return fullness; |
---|
134 | } |
---|
135 | |
---|
136 | |
---|
137 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
138 | void * LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::malloc (size_t sz) |
---|
139 | { |
---|
140 | checkClassInvariant(); |
---|
141 | //printf ("Loose malloc %d (slot size = %d)\n", sz, slotSize); |
---|
142 | assert (sz <= slotSize); |
---|
143 | void * ptr = NULL; |
---|
144 | chunkType * ch = NULL; |
---|
145 | // Always try to allocate from the most-full chunk (resetting |
---|
146 | // lastIndex as we go). |
---|
147 | lastIndex = emptyFraction - 1; // FIX ME! |
---|
148 | while (lastIndex >= 0) { |
---|
149 | ch = myChunks[lastIndex]; |
---|
150 | if (ch == NULL) { |
---|
151 | lastIndex--; |
---|
152 | } else { |
---|
153 | // Got one. |
---|
154 | break; |
---|
155 | } |
---|
156 | } |
---|
157 | if (lastIndex < 0) { |
---|
158 | assert (ch == NULL); |
---|
159 | // There were no chunks available. |
---|
160 | assert ((space - inUse) == 0); |
---|
161 | // Make one with memory from the "super" heap. |
---|
162 | printf ("!!!\n"); |
---|
163 | ch = (chunkType*) theHeap.malloc (chunkSize); |
---|
164 | ch->setHeap (this); |
---|
165 | assert (ch->getNumSlotsFree() > 0); |
---|
166 | printf ("Super malloc %d\n", chunkSize); |
---|
167 | lastIndex = getFullness(ch); |
---|
168 | register chunkType*& head = myChunks[lastIndex]; |
---|
169 | assert (head == NULL); |
---|
170 | ch->setPrev (NULL); |
---|
171 | ch->setNext (NULL); |
---|
172 | head = ch; |
---|
173 | inUse += ch->getNumSlotsInUse(); |
---|
174 | space += ch->getNumSlots(); |
---|
175 | assert (ch->getNumSlotsFree() <= ch->getNumSlots()); |
---|
176 | // FOR NOW!! FIX ME!!! |
---|
177 | assert (ch->getNumSlotsFree() == ch->getNumSlots()); |
---|
178 | printf ("Space, in use was %d, %d\n", space, inUse); |
---|
179 | printf ("Space, in use NOW %d, %d\n", space, inUse); |
---|
180 | } |
---|
181 | assert (ch != NULL); |
---|
182 | assert (ch->getNumSlotsFree() > 0); |
---|
183 | int prevFullness = getFullness (ch); |
---|
184 | int prevInUse = ch->getNumSlotsInUse(); |
---|
185 | assert (ch->getHeap() == this); |
---|
186 | ptr = ch->getSlot(); |
---|
187 | inUse++; |
---|
188 | assert (prevInUse + 1 == ch->getNumSlotsInUse()); |
---|
189 | int newFullness = getFullness (ch); |
---|
190 | if (prevFullness != newFullness) { |
---|
191 | int n = update (ch, prevFullness); |
---|
192 | assert (n == newFullness); |
---|
193 | } |
---|
194 | chunkType * bch = (chunkType *) chunkType::getChunk(ptr); |
---|
195 | assert (bch == ch); |
---|
196 | assert (ptr != NULL); |
---|
197 | checkClassInvariant(); |
---|
198 | return ptr; |
---|
199 | } |
---|
200 | |
---|
201 | |
---|
202 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
203 | void LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::free (void * ptr) { |
---|
204 | chunkType * ch |
---|
205 | = (chunkType *) chunkType::getChunk (ptr); |
---|
206 | assert (ch != NULL); |
---|
207 | (ch->getHeap())->localFree (ptr); |
---|
208 | } |
---|
209 | |
---|
210 | |
---|
211 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
212 | void LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::localFree (void * ptr) { |
---|
213 | checkClassInvariant(); |
---|
214 | printf ("free! (in use = %d, space = %d)\n", inUse, space); |
---|
215 | // Mark the slot in the chunk as free. |
---|
216 | chunkType * ch |
---|
217 | = (chunkType *) chunkType::getChunk (ptr); |
---|
218 | assert (ch != NULL); |
---|
219 | assert (ch->getHeap() == this); |
---|
220 | int prevFullness = getFullness (ch); |
---|
221 | int prevInUse = ch->getNumSlotsInUse(); |
---|
222 | ch->putSlot (ptr); |
---|
223 | inUse--; |
---|
224 | assert (prevInUse - 1 == ch->getNumSlotsInUse()); |
---|
225 | checkClassInvariant(); |
---|
226 | int newIndex = getFullness (ch); |
---|
227 | if (prevFullness != newIndex) { |
---|
228 | int n = update (ch, prevFullness); |
---|
229 | assert (n == newIndex); |
---|
230 | } |
---|
231 | // If we are more than 1/emptyFraction empty, |
---|
232 | // return a mostly-empty chunk to the super heap. |
---|
233 | if ((space - inUse > 2 * chunkSize/slotSize) |
---|
234 | && (emptyFraction * (space - inUse) > space)) { |
---|
235 | printf ("RETURNING A CHUNK!\n"); |
---|
236 | // Find an empty chunk. |
---|
237 | int emptyIndex = 0; |
---|
238 | ch = NULL; |
---|
239 | while (emptyIndex < emptyFraction) { |
---|
240 | ch = myChunks[emptyIndex]; |
---|
241 | if (ch != NULL) |
---|
242 | break; |
---|
243 | emptyIndex++; |
---|
244 | } |
---|
245 | assert (ch != NULL); |
---|
246 | checkClassInvariant(); |
---|
247 | ch->setHeap (NULL); |
---|
248 | // Remove a chunk and give it to the super heap. |
---|
249 | myChunks[emptyIndex] = myChunks[emptyIndex]->getNext(); |
---|
250 | if (myChunks[emptyIndex] != NULL) { |
---|
251 | myChunks[emptyIndex]->setPrev (NULL); |
---|
252 | } |
---|
253 | ch->setPrev (NULL); |
---|
254 | ch->setNext (NULL); |
---|
255 | // A sanity check on the chunk we're about to return. |
---|
256 | assert (ch->getNumSlotsFree() >= 0); |
---|
257 | assert (ch->getNumSlots() >= ch->getNumSlotsFree()); |
---|
258 | printf ("Updating space & in use: was %d, %d (slots in use = %d)\n", |
---|
259 | space, inUse, ch->getNumSlotsInUse()); |
---|
260 | space -= ch->getNumSlots(); |
---|
261 | inUse -= ch->getNumSlotsInUse(); |
---|
262 | printf ("Updating space & in use: NOW %d, %d\n", space, inUse); |
---|
263 | theHeap.free (ch); |
---|
264 | checkClassInvariant(); |
---|
265 | } |
---|
266 | checkClassInvariant(); |
---|
267 | } |
---|
268 | |
---|
269 | |
---|
270 | // Move a chunk, if necessary, into the right list |
---|
271 | // based on its emptiness. |
---|
272 | template <int chunkSize, int slotSize, int emptyFraction, class Super> |
---|
273 | int LooseSlotHeap<chunkSize, slotSize, emptyFraction, Super>::update (chunkType * ch, int prevIndex) |
---|
274 | { |
---|
275 | // Move this chunk if necessary. |
---|
276 | #ifndef NDEBUG |
---|
277 | chunkType * bch = myChunks[prevIndex]; |
---|
278 | while (bch != NULL) { |
---|
279 | if (bch == ch) |
---|
280 | break; |
---|
281 | bch = bch->getNext(); |
---|
282 | } |
---|
283 | assert (bch == ch); |
---|
284 | #endif |
---|
285 | int newIndex = getFullness(ch); |
---|
286 | // printf ("newIndex = %d\n", newIndex); |
---|
287 | // Reset last index (for simplicity). // FIX ME?? |
---|
288 | // Remove the chunk from its current list. |
---|
289 | if (ch == myChunks[prevIndex]) { |
---|
290 | myChunks[prevIndex] = myChunks[prevIndex]->getNext(); |
---|
291 | } |
---|
292 | ///// lastIndex = emptyFraction - 1; |
---|
293 | if (ch->getPrev() != NULL) { |
---|
294 | ch->getPrev()->setNext(ch->getNext()); |
---|
295 | } |
---|
296 | if (ch->getNext() != NULL) { |
---|
297 | ch->getNext()->setPrev(ch->getPrev()); |
---|
298 | } |
---|
299 | // Add it to the newIndex list. |
---|
300 | chunkType*& head = myChunks[newIndex]; |
---|
301 | ch->setPrev (NULL); |
---|
302 | ch->setNext (head); |
---|
303 | if (head != NULL) { |
---|
304 | head->setPrev(ch); |
---|
305 | } |
---|
306 | head = ch; |
---|
307 | // Verify that the chunk is in the right list. |
---|
308 | #ifndef NDEBUG |
---|
309 | bch = myChunks[newIndex]; |
---|
310 | while (bch != NULL) { |
---|
311 | if (bch == ch) |
---|
312 | break; |
---|
313 | bch = bch->getNext(); |
---|
314 | } |
---|
315 | assert (bch == ch); |
---|
316 | #endif |
---|
317 | return newIndex; |
---|
318 | } |
---|
319 | |
---|
320 | |
---|
321 | |
---|
322 | #endif |
---|