[thirdparty/squid.git] / src / repl / lru / store_repl_lru.cc


/*
 * $Id: store_repl_lru.cc,v 1.6 2001/01/12 00:37:36 wessels Exp $
 *
 * DEBUG: section ?     LRU Removal policy
 * AUTHOR: Henrik Nordstrom
 *
 * SQUID Web Proxy Cache          http://www.squid-cache.org/
 * ----------------------------------------------------------
 *
 *  Squid is the result of efforts by numerous individuals from
 *  the Internet community; see the CONTRIBUTORS file for full
 *  details.   Many organizations have provided support for Squid's
 *  development; see the SPONSORS file for full details.  Squid is
 *  Copyrighted (C) 2001 by the Regents of the University of
 *  California; see the COPYRIGHT file for full details.  Squid
 *  incorporates software developed and/or copyrighted by other
 *  sources; see the CREDITS file for full details.
 *
 *  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, USA.
 *
 */

#include "squid.h"

REMOVALPOLICYCREATE createRemovalPolicy_lru;

typedef struct _LruPolicyData LruPolicyData;
struct _LruPolicyData {
    RemovalPolicy *policy;
    dlink_list list;
    int count;
    int nwalkers;
    enum heap_entry_type {
	TYPE_UNKNOWN = 0, TYPE_STORE_ENTRY, TYPE_STORE_MEM
    } type;
};

/* Hack to avoid having to remember the RemovalPolicyNode location.
 * Needed by the purge walker to clear the policy information
 */
static enum heap_entry_type
repl_guessType(StoreEntry * entry, RemovalPolicyNode * node)
{
    if (node == &entry->repl)
	return TYPE_STORE_ENTRY;
    if (entry->mem_obj && node == &entry->mem_obj->repl)
	return TYPE_STORE_MEM;
    fatal("Heap Replacement: Unknown StoreEntry node type");
    return TYPE_UNKNOWN;
}
#define SET_POLICY_NODE(entry,value) \
    switch(lru->type) { \
    case TYPE_STORE_ENTRY: entry->repl.data = value; break ; \
    case TYPE_STORE_MEM: entry->mem_obj->repl.data = value ; break ; \
    default: break; \
    }

typedef struct _LruNode LruNode;
struct _LruNode {
    /* Note: the dlink_node MUST be the first member of the LruNode
     * structure. This member is later pointer typecasted to LruNode *.
     */
    dlink_node node;
};

static MemPool *lru_node_pool = NULL;
static int nr_lru_policies = 0;

static void
lru_add(RemovalPolicy * policy, StoreEntry * entry, RemovalPolicyNode * node)
{
    LruPolicyData *lru = policy->_data;
    LruNode *lru_node;
    assert(!node->data);
    node->data = lru_node = memPoolAlloc(lru_node_pool);
    dlinkAddTail(entry, &lru_node->node, &lru->list);
    lru->count += 1;
    if (!lru->type)
	lru->type = repl_guessType(entry, node);
}

static void
lru_remove(RemovalPolicy * policy, StoreEntry * entry, RemovalPolicyNode * node)
{
    LruPolicyData *lru = policy->_data;
    LruNode *lru_node = node->data;
    if (!lru_node)
	return;
    /*
     * It seems to be possible for an entry to exist in the hash
     * but not be in the LRU list, so check for that case rather
     * than suffer a NULL pointer access.
     */
    if (NULL == lru_node->node.data)
	return;
    assert(lru_node->node.data == entry);
    node->data = NULL;
    dlinkDelete(&lru_node->node, &lru->list);
    memPoolFree(lru_node_pool, lru_node);
    lru->count -= 1;
}

static void
lru_referenced(RemovalPolicy * policy, const StoreEntry * entry,
    RemovalPolicyNode * node)
{
    LruPolicyData *lru = policy->_data;
    LruNode *lru_node = node->data;
    if (!lru_node)
	return;
    dlinkDelete(&lru_node->node, &lru->list);
    dlinkAddTail((void *) entry, &lru_node->node, &lru->list);
}

/** RemovalPolicyWalker **/

typedef struct _LruWalkData LruWalkData;
struct _LruWalkData {
    LruNode *current;
};

const StoreEntry *
lru_walkNext(RemovalPolicyWalker * walker)
{
    LruWalkData *lru_walk = walker->_data;
    LruNode *lru_node = lru_walk->current;
    if (!lru_node)
	return NULL;
    lru_walk->current = (LruNode *) lru_node->node.next;
    return (StoreEntry *) lru_node->node.data;
}

static void
lru_walkDone(RemovalPolicyWalker * walker)
{
    RemovalPolicy *policy = walker->_policy;
    LruPolicyData *lru = policy->_data;
    assert(strcmp(policy->_type, "lru") == 0);
    assert(lru->nwalkers > 0);
    lru->nwalkers -= 1;
    safe_free(walker->_data);
    cbdataFree(walker);
}

static RemovalPolicyWalker *
lru_walkInit(RemovalPolicy * policy)
{
    LruPolicyData *lru = policy->_data;
    RemovalPolicyWalker *walker;
    LruWalkData *lru_walk;
    lru->nwalkers += 1;
    walker = CBDATA_ALLOC(RemovalPolicyWalker, NULL);
    lru_walk = xcalloc(1, sizeof(*lru_walk));
    walker->_policy = policy;
    walker->_data = lru_walk;
    walker->Next = lru_walkNext;
    walker->Done = lru_walkDone;
    lru_walk->current = (LruNode *) lru->list.head;
    return walker;
}

/** RemovalPurgeWalker **/

typedef struct _LruPurgeData LruPurgeData;
struct _LruPurgeData {
    LruNode *current;
    LruNode *start;
};

static StoreEntry *
lru_purgeNext(RemovalPurgeWalker * walker)
{
    LruPurgeData *lru_walker = walker->_data;
    RemovalPolicy *policy = walker->_policy;
    LruPolicyData *lru = policy->_data;
    LruNode *lru_node;
    StoreEntry *entry;
  try_again:
    lru_node = lru_walker->current;
    if (!lru_node || walker->scanned >= walker->max_scan)
	return NULL;
    walker->scanned += 1;
    lru_walker->current = (LruNode *) lru_node->node.next;
    if (lru_walker->current == lru_walker->start) {
	/* Last node found */
	lru_walker->current = NULL;
    }
    entry = (StoreEntry *) lru_node->node.data;
    dlinkDelete(&lru_node->node, &lru->list);
    if (storeEntryLocked(entry)) {
	/* Shit, it is locked. we can't return this one */
	walker->locked++;
	dlinkAddTail(entry, &lru_node->node, &lru->list);
	goto try_again;
    }
    memPoolFree(lru_node_pool, lru_node);
    lru->count -= 1;
    SET_POLICY_NODE(entry, NULL);
    return entry;
}

static void
lru_purgeDone(RemovalPurgeWalker * walker)
{
    RemovalPolicy *policy = walker->_policy;
    LruPolicyData *lru = policy->_data;
    assert(strcmp(policy->_type, "lru") == 0);
    assert(lru->nwalkers > 0);
    lru->nwalkers -= 1;
    safe_free(walker->_data);
    cbdataFree(walker);
}

static RemovalPurgeWalker *
lru_purgeInit(RemovalPolicy * policy, int max_scan)
{
    LruPolicyData *lru = policy->_data;
    RemovalPurgeWalker *walker;
    LruPurgeData *lru_walk;
    lru->nwalkers += 1;
    walker = CBDATA_ALLOC(RemovalPurgeWalker, NULL);
    lru_walk = xcalloc(1, sizeof(*lru_walk));
    walker->_policy = policy;
    walker->_data = lru_walk;
    walker->max_scan = max_scan;
    walker->Next = lru_purgeNext;
    walker->Done = lru_purgeDone;
    lru_walk->start = lru_walk->current = (LruNode *) lru->list.head;
    return walker;
}

static void
lru_free(RemovalPolicy * policy)
{
    LruPolicyData *lru = policy->_data;
    /* Make some verification of the policy state */
    assert(strcmp(policy->_type, "lru") == 0);
    assert(lru->nwalkers);
    assert(lru->count);
    /* Ok, time to destroy this policy */
    safe_free(policy->_data);
    memset(policy, 0, sizeof(*policy));
    cbdataFree(policy);
}

RemovalPolicy *
createRemovalPolicy_lru(wordlist * args)
{
    RemovalPolicy *policy;
    LruPolicyData *lru_data;
    /* no arguments expected or understood */
    assert(!args);
    /* Initialize */
    if (!lru_node_pool)
	lru_node_pool = memPoolCreate("LRU policy node", sizeof(LruNode));
    /* Allocate the needed structures */
    lru_data = xcalloc(1, sizeof(*lru_data));
    policy = CBDATA_ALLOC(RemovalPolicy, NULL);
    /* Initialize the URL data */
    lru_data->policy = policy;
    /* Populate the policy structure */
    policy->_type = "lru";
    policy->_data = lru_data;
    policy->Free = lru_free;
    policy->Add = lru_add;
    policy->Remove = lru_remove;
    policy->Referenced = lru_referenced;
    policy->Dereferenced = lru_referenced;
    policy->WalkInit = lru_walkInit;
    policy->PurgeInit = lru_purgeInit;
    /* Increase policy usage count */
    nr_lru_policies += 0;
    return policy;
}
Commit	Line	Data
6a566b9c	1
6a566b9c	2	/*
2b6662ba	3	* $Id: store_repl_lru.cc,v 1.6 2001/01/12 00:37:36 wessels Exp $
6a566b9c	4	*
	5	* DEBUG: section ? LRU Removal policy
	6	* AUTHOR: Henrik Nordstrom
	7	*
2b6662ba	8	* SQUID Web Proxy Cache http://www.squid-cache.org/
6a566b9c	9	* ----------------------------------------------------------
6a566b9c	10	*
2b6662ba	11	* Squid is the result of efforts by numerous individuals from
	12	* the Internet community; see the CONTRIBUTORS file for full
	13	* details. Many organizations have provided support for Squid's
	14	* development; see the SPONSORS file for full details. Squid is
	15	* Copyrighted (C) 2001 by the Regents of the University of
	16	* California; see the COPYRIGHT file for full details. Squid
	17	* incorporates software developed and/or copyrighted by other
	18	* sources; see the CREDITS file for full details.
6a566b9c	19	*
	20	* This program is free software; you can redistribute it and/or modify
	21	* it under the terms of the GNU General Public License as published by
	22	* the Free Software Foundation; either version 2 of the License, or
	23	* (at your option) any later version.
	24	*
	25	* This program is distributed in the hope that it will be useful,
	26	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	27	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	28	* GNU General Public License for more details.
	29	*
	30	* You should have received a copy of the GNU General Public License
	31	* along with this program; if not, write to the Free Software
	32	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
	33	*
	34	*/
	35
	36	#include "squid.h"
	37
	38	REMOVALPOLICYCREATE createRemovalPolicy_lru;
	39
	40	typedef struct _LruPolicyData LruPolicyData;
	41	struct _LruPolicyData {
	42	RemovalPolicy *policy;
	43	dlink_list list;
	44	int count;
	45	int nwalkers;
9f913cf1	46	enum heap_entry_type {
	47	TYPE_UNKNOWN = 0, TYPE_STORE_ENTRY, TYPE_STORE_MEM
	48	} type;
6a566b9c	49	};
	50
	51	/* Hack to avoid having to remember the RemovalPolicyNode location.
	52	* Needed by the purge walker to clear the policy information
	53	*/
	54	static enum heap_entry_type
	55	repl_guessType(StoreEntry * entry, RemovalPolicyNode * node)
	56	{
	57	if (node == &entry->repl)
	58	return TYPE_STORE_ENTRY;
	59	if (entry->mem_obj && node == &entry->mem_obj->repl)
	60	return TYPE_STORE_MEM;
	61	fatal("Heap Replacement: Unknown StoreEntry node type");
	62	return TYPE_UNKNOWN;
	63	}
	64	#define SET_POLICY_NODE(entry,value) \
	65	switch(lru->type) { \
	66	case TYPE_STORE_ENTRY: entry->repl.data = value; break ; \
	67	case TYPE_STORE_MEM: entry->mem_obj->repl.data = value ; break ; \
	68	default: break; \
	69	}
	70
	71	typedef struct _LruNode LruNode;
9f913cf1	72	struct _LruNode {
6a566b9c	73	/* Note: the dlink_node MUST be the first member of the LruNode
	74	* structure. This member is later pointer typecasted to LruNode *.
	75	*/
	76	dlink_node node;
	77	};
	78
	79	static MemPool *lru_node_pool = NULL;
	80	static int nr_lru_policies = 0;
	81
	82	static void
	83	lru_add(RemovalPolicy * policy, StoreEntry * entry, RemovalPolicyNode * node)
	84	{
	85	LruPolicyData *lru = policy->_data;
	86	LruNode *lru_node;
	87	assert(!node->data);
	88	node->data = lru_node = memPoolAlloc(lru_node_pool);
	89	dlinkAddTail(entry, &lru_node->node, &lru->list);
	90	lru->count += 1;
	91	if (!lru->type)
	92	lru->type = repl_guessType(entry, node);
	93	}
	94
	95	static void
	96	lru_remove(RemovalPolicy * policy, StoreEntry * entry, RemovalPolicyNode * node)
	97	{
	98	LruPolicyData *lru = policy->_data;
	99	LruNode *lru_node = node->data;
	100	if (!lru_node)
	101	return;
75240ca9	102	/*
	103	* It seems to be possible for an entry to exist in the hash
	104	* but not be in the LRU list, so check for that case rather
	105	* than suffer a NULL pointer access.
	106	*/
	107	if (NULL == lru_node->node.data)
	108	return;
6a566b9c	109	assert(lru_node->node.data == entry);
	110	node->data = NULL;
	111	dlinkDelete(&lru_node->node, &lru->list);
	112	memPoolFree(lru_node_pool, lru_node);
	113	lru->count -= 1;
	114	}
	115
	116	static void
	117	lru_referenced(RemovalPolicy * policy, const StoreEntry * entry,
	118	RemovalPolicyNode * node)
	119	{
	120	LruPolicyData *lru = policy->_data;
	121	LruNode *lru_node = node->data;
	122	if (!lru_node)
	123	return;
	124	dlinkDelete(&lru_node->node, &lru->list);
	125	dlinkAddTail((void *) entry, &lru_node->node, &lru->list);
	126	}
	127
	128	/ RemovalPolicyWalker /
	129
	130	typedef struct _LruWalkData LruWalkData;
9f913cf1	131	struct _LruWalkData {
6a566b9c	132	LruNode *current;
	133	};
	134
	135	const StoreEntry *
	136	lru_walkNext(RemovalPolicyWalker * walker)
	137	{
	138	LruWalkData *lru_walk = walker->_data;
	139	LruNode *lru_node = lru_walk->current;
	140	if (!lru_node)
	141	return NULL;
	142	lru_walk->current = (LruNode *) lru_node->node.next;
	143	return (StoreEntry *) lru_node->node.data;
	144	}
	145
	146	static void
	147	lru_walkDone(RemovalPolicyWalker * walker)
	148	{
	149	RemovalPolicy *policy = walker->_policy;
	150	LruPolicyData *lru = policy->_data;
	151	assert(strcmp(policy->_type, "lru") == 0);
	152	assert(lru->nwalkers > 0);
	153	lru->nwalkers -= 1;
	154	safe_free(walker->_data);
	155	cbdataFree(walker);
	156	}
	157
	158	static RemovalPolicyWalker *
	159	lru_walkInit(RemovalPolicy * policy)
	160	{
	161	LruPolicyData *lru = policy->_data;
	162	RemovalPolicyWalker *walker;
	163	LruWalkData *lru_walk;
	164	lru->nwalkers += 1;
468ae12b	165	walker = CBDATA_ALLOC(RemovalPolicyWalker, NULL);
6a566b9c	166	lru_walk = xcalloc(1, sizeof(*lru_walk));
	167	walker->_policy = policy;
	168	walker->_data = lru_walk;
	169	walker->Next = lru_walkNext;
	170	walker->Done = lru_walkDone;
	171	lru_walk->current = (LruNode *) lru->list.head;
6a566b9c	172	return walker;
	173	}
	174
	175	/ RemovalPurgeWalker /
	176
	177	typedef struct _LruPurgeData LruPurgeData;
9f913cf1	178	struct _LruPurgeData {
6a566b9c	179	LruNode *current;
	180	LruNode *start;
	181	};
	182
	183	static StoreEntry *
	184	lru_purgeNext(RemovalPurgeWalker * walker)
	185	{
	186	LruPurgeData *lru_walker = walker->_data;
	187	RemovalPolicy *policy = walker->_policy;
	188	LruPolicyData *lru = policy->_data;
	189	LruNode *lru_node;
	190	StoreEntry *entry;
	191	try_again:
	192	lru_node = lru_walker->current;
	193	if (!lru_node \|\| walker->scanned >= walker->max_scan)
	194	return NULL;
	195	walker->scanned += 1;
	196	lru_walker->current = (LruNode *) lru_node->node.next;
	197	if (lru_walker->current == lru_walker->start) {
	198	/* Last node found */
	199	lru_walker->current = NULL;
	200	}
	201	entry = (StoreEntry *) lru_node->node.data;
	202	dlinkDelete(&lru_node->node, &lru->list);
	203	if (storeEntryLocked(entry)) {
	204	/* Shit, it is locked. we can't return this one */
	205	walker->locked++;
	206	dlinkAddTail(entry, &lru_node->node, &lru->list);
	207	goto try_again;
	208	}
	209	memPoolFree(lru_node_pool, lru_node);
	210	lru->count -= 1;
	211	SET_POLICY_NODE(entry, NULL);
	212	return entry;
	213	}
	214
	215	static void
	216	lru_purgeDone(RemovalPurgeWalker * walker)
	217	{
	218	RemovalPolicy *policy = walker->_policy;
	219	LruPolicyData *lru = policy->_data;
	220	assert(strcmp(policy->_type, "lru") == 0);
	221	assert(lru->nwalkers > 0);
	222	lru->nwalkers -= 1;
	223	safe_free(walker->_data);
	224	cbdataFree(walker);
	225	}
	226
	227	static RemovalPurgeWalker *
	228	lru_purgeInit(RemovalPolicy * policy, int max_scan)
	229	{
	230	LruPolicyData *lru = policy->_data;
	231	RemovalPurgeWalker *walker;
	232	LruPurgeData *lru_walk;
	233	lru->nwalkers += 1;
468ae12b	234	walker = CBDATA_ALLOC(RemovalPurgeWalker, NULL);
6a566b9c	235	lru_walk = xcalloc(1, sizeof(*lru_walk));
	236	walker->_policy = policy;
	237	walker->_data = lru_walk;
	238	walker->max_scan = max_scan;
	239	walker->Next = lru_purgeNext;
	240	walker->Done = lru_purgeDone;
	241	lru_walk->start = lru_walk->current = (LruNode *) lru->list.head;
6a566b9c	242	return walker;
	243	}
	244
	245	static void
	246	lru_free(RemovalPolicy * policy)
	247	{
	248	LruPolicyData *lru = policy->_data;
	249	/* Make some verification of the policy state */
	250	assert(strcmp(policy->_type, "lru") == 0);
	251	assert(lru->nwalkers);
	252	assert(lru->count);
	253	/* Ok, time to destroy this policy */
	254	safe_free(policy->_data);
	255	memset(policy, 0, sizeof(*policy));
	256	cbdataFree(policy);
	257	}
	258
	259	RemovalPolicy *
9f913cf1	260	createRemovalPolicy_lru(wordlist * args)
6a566b9c	261	{
	262	RemovalPolicy *policy;
	263	LruPolicyData *lru_data;
	264	/* no arguments expected or understood */
	265	assert(!args);
	266	/* Initialize */
	267	if (!lru_node_pool)
	268	lru_node_pool = memPoolCreate("LRU policy node", sizeof(LruNode));
	269	/* Allocate the needed structures */
6a566b9c	270	lru_data = xcalloc(1, sizeof(*lru_data));
468ae12b	271	policy = CBDATA_ALLOC(RemovalPolicy, NULL);
6a566b9c	272	/* Initialize the URL data */
	273	lru_data->policy = policy;
	274	/* Populate the policy structure */
	275	policy->_type = "lru";
	276	policy->_data = lru_data;
	277	policy->Free = lru_free;
	278	policy->Add = lru_add;
	279	policy->Remove = lru_remove;
	280	policy->Referenced = lru_referenced;
	281	policy->Dereferenced = lru_referenced;
	282	policy->WalkInit = lru_walkInit;
	283	policy->PurgeInit = lru_purgeInit;
	284	/* Increase policy usage count */
	285	nr_lru_policies += 0;
	286	return policy;
	287	}