3 * $Id: store_repl_heap.cc,v 1.21 2006/08/21 00:50:47 robertc Exp $
5 * DEBUG: section ? HEAP based removal policies
6 * AUTHOR: Henrik Nordstrom
8 * Based on the ideas of the heap policy implemented by John Dilley of
9 * Hewlett Packard. Rewritten from scratch when modularizing the removal
10 * policy implementation of Squid.
12 * For details on the original heap policy work and the thinking behind see
13 * http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html
16 * SQUID Web Proxy Cache http://www.squid-cache.org/
17 * ----------------------------------------------------------
19 * Squid is the result of efforts by numerous individuals from
20 * the Internet community; see the CONTRIBUTORS file for full
21 * details. Many organizations have provided support for Squid's
22 * development; see the SPONSORS file for full details. Squid is
23 * Copyrighted (C) 2001 by the Regents of the University of
24 * California; see the COPYRIGHT file for full details. Squid
25 * incorporates software developed and/or copyrighted by other
26 * sources; see the CREDITS file for full details.
28 * This program is free software; you can redistribute it and/or modify
29 * it under the terms of the GNU General Public License as published by
30 * the Free Software Foundation; either version 2 of the License, or
31 * (at your option) any later version.
33 * This program is distributed in the hope that it will be useful,
34 * but WITHOUT ANY WARRANTY; without even the implied warranty of
35 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
36 * GNU General Public License for more details.
38 * You should have received a copy of the GNU General Public License
39 * along with this program; if not, write to the Free Software
40 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
46 #include "store_heap_replacement.h"
48 #include "MemObject.h"
51 REMOVALPOLICYCREATE createRemovalPolicy_heap
;
53 static int nr_heap_policies
= 0;
57 void setPolicyNode (StoreEntry
*, void *) const;
58 RemovalPolicy
*policy
;
60 heap_key_func
*keyfunc
;
63 enum heap_entry_type
{
64 TYPE_UNKNOWN
= 0, TYPE_STORE_ENTRY
, TYPE_STORE_MEM
68 /* Hack to avoid having to remember the RemovalPolicyNode location.
69 * Needed by the purge walker.
71 static enum HeapPolicyData::heap_entry_type
72 heap_guessType(StoreEntry
* entry
, RemovalPolicyNode
* node
)
74 if (node
== &entry
->repl
)
75 return HeapPolicyData::TYPE_STORE_ENTRY
;
77 if (entry
->mem_obj
&& node
== &entry
->mem_obj
->repl
)
78 return HeapPolicyData::TYPE_STORE_MEM
;
80 fatal("Heap Replacement: Unknown StoreEntry node type");
82 return HeapPolicyData::TYPE_UNKNOWN
;
86 HeapPolicyData::setPolicyNode (StoreEntry
*entry
, void *value
) const
90 case TYPE_STORE_ENTRY
:
91 entry
->repl
.data
= value
;
95 entry
->mem_obj
->repl
.data
= value
;
104 heap_add(RemovalPolicy
* policy
, StoreEntry
* entry
, RemovalPolicyNode
* node
)
106 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
109 if (EBIT_TEST(entry
->flags
, ENTRY_SPECIAL
))
110 return; /* We won't manage these.. they messes things up */
112 node
->data
= heap_insert(heap
->theHeap
, entry
);
117 heap
->type
= heap_guessType(entry
, node
);
119 /* Add a little more variance to the aging factor */
120 heap
->theHeap
->age
+= heap
->theHeap
->age
/ 100000000;
124 heap_remove(RemovalPolicy
* policy
, StoreEntry
* entry
,
125 RemovalPolicyNode
* node
)
127 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
128 heap_node
*hnode
= (heap_node
*)node
->data
;
133 heap_delete(heap
->theHeap
, hnode
);
141 heap_referenced(RemovalPolicy
* policy
, const StoreEntry
* entry
,
142 RemovalPolicyNode
* node
)
144 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
145 heap_node
*hnode
= (heap_node
*)node
->data
;
150 heap_update(heap
->theHeap
, hnode
, (StoreEntry
*) entry
);
153 /** RemovalPolicyWalker **/
155 typedef struct _HeapWalkData HeapWalkData
;
162 static const StoreEntry
*
163 heap_walkNext(RemovalPolicyWalker
* walker
)
165 HeapWalkData
*heap_walk
= (HeapWalkData
*)walker
->_data
;
166 RemovalPolicy
*policy
= walker
->_policy
;
167 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
170 if (heap_walk
->current
>= heap_nodes(heap
->theHeap
))
171 return NULL
; /* done */
173 entry
= (StoreEntry
*) heap_peep(heap
->theHeap
, heap_walk
->current
++);
179 heap_walkDone(RemovalPolicyWalker
* walker
)
181 RemovalPolicy
*policy
= walker
->_policy
;
182 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
183 assert(strcmp(policy
->_type
, "heap") == 0);
184 assert(heap
->nwalkers
> 0);
186 safe_free(walker
->_data
);
190 static RemovalPolicyWalker
*
191 heap_walkInit(RemovalPolicy
* policy
)
193 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
194 RemovalPolicyWalker
*walker
;
195 HeapWalkData
*heap_walk
;
197 walker
= new RemovalPolicyWalker
;
198 heap_walk
= (HeapWalkData
*)xcalloc(1, sizeof(*heap_walk
));
199 heap_walk
->current
= 0;
200 walker
->_policy
= policy
;
201 walker
->_data
= heap_walk
;
202 walker
->Next
= heap_walkNext
;
203 walker
->Done
= heap_walkDone
;
207 /** RemovalPurgeWalker **/
209 typedef struct _HeapPurgeData HeapPurgeData
;
211 struct _HeapPurgeData
213 link_list
*locked_entries
;
218 heap_purgeNext(RemovalPurgeWalker
* walker
)
220 HeapPurgeData
*heap_walker
= (HeapPurgeData
*)walker
->_data
;
221 RemovalPolicy
*policy
= walker
->_policy
;
222 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
228 if (!heap_nodes(heap
->theHeap
) > 0)
229 return NULL
; /* done */
231 age
= heap_peepminkey(heap
->theHeap
);
233 entry
= (StoreEntry
*)heap_extractmin(heap
->theHeap
);
235 if (storeEntryLocked(entry
)) {
240 linklistPush(&heap_walker
->locked_entries
, entry
);
245 heap_walker
->min_age
= age
;
246 heap
->setPolicyNode(entry
, NULL
);
251 heap_purgeDone(RemovalPurgeWalker
* walker
)
253 HeapPurgeData
*heap_walker
= (HeapPurgeData
*)walker
->_data
;
254 RemovalPolicy
*policy
= walker
->_policy
;
255 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
257 assert(strcmp(policy
->_type
, "heap") == 0);
258 assert(heap
->nwalkers
> 0);
261 if (heap_walker
->min_age
> 0) {
262 heap
->theHeap
->age
= heap_walker
->min_age
;
263 debug(81, 3) ("heap_purgeDone: Heap age set to %f\n",
264 (double) heap
->theHeap
->age
);
268 * Reinsert the locked entries
270 while ((entry
= (StoreEntry
*)linklistShift(&heap_walker
->locked_entries
))) {
271 heap_node
*node
= heap_insert(heap
->theHeap
, entry
);
272 heap
->setPolicyNode(entry
, node
);
276 safe_free(walker
->_data
);
280 static RemovalPurgeWalker
*
281 heap_purgeInit(RemovalPolicy
* policy
, int max_scan
)
283 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
284 RemovalPurgeWalker
*walker
;
285 HeapPurgeData
*heap_walk
;
287 walker
= new RemovalPurgeWalker
;
288 heap_walk
= (HeapPurgeData
*)xcalloc(1, sizeof(*heap_walk
));
289 heap_walk
->min_age
= 0.0;
290 heap_walk
->locked_entries
= NULL
;
291 walker
->_policy
= policy
;
292 walker
->_data
= heap_walk
;
293 walker
->max_scan
= max_scan
;
294 walker
->Next
= heap_purgeNext
;
295 walker
->Done
= heap_purgeDone
;
300 heap_free(RemovalPolicy
* policy
)
302 HeapPolicyData
*heap
= (HeapPolicyData
*)policy
->_data
;
303 /* Make some verification of the policy state */
304 assert(strcmp(policy
->_type
, "heap") == 0);
305 assert(heap
->nwalkers
);
307 /* Ok, time to destroy this policy */
309 memset(policy
, 0, sizeof(*policy
));
314 createRemovalPolicy_heap(wordlist
* args
)
316 RemovalPolicy
*policy
;
317 HeapPolicyData
*heap_data
;
319 /* Allocate the needed structures */
320 policy
= new RemovalPolicy
;
321 heap_data
= (HeapPolicyData
*)xcalloc(1, sizeof(*heap_data
));
322 /* Initialize the policy data */
323 heap_data
->policy
= policy
;
329 debug(81, 1) ("createRemovalPolicy_heap: No key type specified. Using LRU\n");
333 if (!strcmp(keytype
, "GDSF"))
334 heap_data
->keyfunc
= HeapKeyGen_StoreEntry_GDSF
;
335 else if (!strcmp(keytype
, "LFUDA"))
336 heap_data
->keyfunc
= HeapKeyGen_StoreEntry_LFUDA
;
337 else if (!strcmp(keytype
, "LRU"))
338 heap_data
->keyfunc
= HeapKeyGen_StoreEntry_LRU
;
340 debug(81, 0) ("createRemovalPolicy_heap: Unknown key type \"%s\". Using LRU\n",
342 heap_data
->keyfunc
= HeapKeyGen_StoreEntry_LRU
;
345 /* No additional arguments expected */
348 heap_data
->theHeap
= new_heap(1000, heap_data
->keyfunc
);
350 heap_data
->theHeap
->age
= 1.0;
352 /* Populate the policy structure */
353 policy
->_type
= "heap";
355 policy
->_data
= heap_data
;
357 policy
->Free
= heap_free
;
359 policy
->Add
= heap_add
;
361 policy
->Remove
= heap_remove
;
363 policy
->Referenced
= NULL
;
365 policy
->Dereferenced
= heap_referenced
;
367 policy
->WalkInit
= heap_walkInit
;
369 policy
->PurgeInit
= heap_purgeInit
;
371 /* Increase policy usage count */
372 nr_heap_policies
+= 0;