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/*
* DEBUG: section 71 Store Digest Manager
* AUTHOR: Alex Rousskov
*
* 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.
*
*/
/*
* TODO: We probably do not track all the cases when
* storeDigestNoteStoreReady() must be called; this may prevent
* storeDigestRebuild/write schedule to be activated
*/
#include "squid.h"
#include "Debug.h"
#include "event.h"
#include "globals.h"
#include "mgr/Registration.h"
#include "store_digest.h"
#if USE_CACHE_DIGESTS
#include "CacheDigest.h"
#include "HttpReply.h"
#include "HttpRequest.h"
#include "internal.h"
#include "MemObject.h"
#include "PeerDigest.h"
#include "refresh.h"
#include "SquidConfig.h"
#include "SquidTime.h"
#include "Store.h"
#include "StoreSearch.h"
#if HAVE_MATH_H
#include <math.h>
#endif
/*
* local types
*/
class StoreDigestState
{
public:
StoreDigestCBlock cblock;
int rebuild_lock; /* bucket number */
StoreEntry * rewrite_lock; /* points to store entry with the digest */
StoreSearchPointer theSearch;
int rewrite_offset;
int rebuild_count;
int rewrite_count;
};
typedef struct {
int del_count; /* #store entries deleted from store_digest */
int del_lost_count; /* #store entries not found in store_digest on delete */
int add_count; /* #store entries accepted to store_digest */
int add_coll_count; /* #accepted entries that collided with existing ones */
int rej_count; /* #store entries not accepted to store_digest */
int rej_coll_count; /* #not accepted entries that collided with existing ones */
} StoreDigestStats;
/* local vars */
static StoreDigestState sd_state;
static StoreDigestStats sd_stats;
/* local prototypes */
static void storeDigestRebuildStart(void *datanotused);
static void storeDigestRebuildResume(void);
static void storeDigestRebuildFinish(void);
static void storeDigestRebuildStep(void *datanotused);
static void storeDigestRewriteStart(void *);
static void storeDigestRewriteResume(void);
static void storeDigestRewriteFinish(StoreEntry * e);
static EVH storeDigestSwapOutStep;
static void storeDigestCBlockSwapOut(StoreEntry * e);
static int storeDigestCalcCap(void);
static int storeDigestResize(void);
static void storeDigestAdd(const StoreEntry *);
#endif /* USE_CACHE_DIGESTS */
static void
storeDigestRegisterWithCacheManager(void)
{
Mgr::RegisterAction("store_digest", "Store Digest", storeDigestReport, 0, 1);
}
/*
* PUBLIC FUNCTIONS
*/
void
storeDigestInit(void)
{
storeDigestRegisterWithCacheManager();
#if USE_CACHE_DIGESTS
const int cap = storeDigestCalcCap();
if (!Config.onoff.digest_generation) {
store_digest = NULL;
debugs(71, 3, "Local cache digest generation disabled");
return;
}
store_digest = cacheDigestCreate(cap, Config.digest.bits_per_entry);
debugs(71, DBG_IMPORTANT, "Local cache digest enabled; rebuild/rewrite every " <<
(int) Config.digest.rebuild_period << "/" <<
(int) Config.digest.rewrite_period << " sec");
memset(&sd_state, 0, sizeof(sd_state));
#else
store_digest = NULL;
debugs(71, 3, "Local cache digest is 'off'");
#endif
}
/* called when store_rebuild completes */
void
storeDigestNoteStoreReady(void)
{
#if USE_CACHE_DIGESTS
if (Config.onoff.digest_generation) {
storeDigestRebuildStart(NULL);
storeDigestRewriteStart(NULL);
}
#endif
}
//TODO: this seems to be dead code. Is it needed?
void
storeDigestDel(const StoreEntry * entry)
{
#if USE_CACHE_DIGESTS
if (!Config.onoff.digest_generation) {
return;
}
assert(entry && store_digest);
debugs(71, 6, "storeDigestDel: checking entry, key: " << entry->getMD5Text());
if (!EBIT_TEST(entry->flags, KEY_PRIVATE)) {
if (!cacheDigestTest(store_digest, (const cache_key *)entry->key)) {
++sd_stats.del_lost_count;
debugs(71, 6, "storeDigestDel: lost entry, key: " << entry->getMD5Text() << " url: " << entry->url() );
} else {
++sd_stats.del_count;
cacheDigestDel(store_digest, (const cache_key *)entry->key);
debugs(71, 6, "storeDigestDel: deled entry, key: " << entry->getMD5Text());
}
}
#endif //USE_CACHE_DIGESTS
}
void
storeDigestReport(StoreEntry * e)
{
#if USE_CACHE_DIGESTS
if (!Config.onoff.digest_generation) {
return;
}
if (store_digest) {
cacheDigestReport(store_digest, "store", e);
storeAppendPrintf(e, "\t added: %d rejected: %d ( %.2f %%) del-ed: %d\n",
sd_stats.add_count,
sd_stats.rej_count,
xpercent(sd_stats.rej_count, sd_stats.rej_count + sd_stats.add_count),
sd_stats.del_count);
storeAppendPrintf(e, "\t collisions: on add: %.2f %% on rej: %.2f %%\n",
xpercent(sd_stats.add_coll_count, sd_stats.add_count),
xpercent(sd_stats.rej_coll_count, sd_stats.rej_count));
} else {
storeAppendPrintf(e, "store digest: disabled.\n");
}
#endif //USE_CACHE_DIGESTS
}
/*
* LOCAL FUNCTIONS
*/
#if USE_CACHE_DIGESTS
/* should we digest this entry? used by storeDigestAdd() */
static int
storeDigestAddable(const StoreEntry * e)
{
/* add some stats! XXX */
debugs(71, 6, "storeDigestAddable: checking entry, key: " << e->getMD5Text());
/* check various entry flags (mimics StoreEntry::checkCachable XXX) */
if (!EBIT_TEST(e->flags, ENTRY_CACHABLE)) {
debugs(71, 6, "storeDigestAddable: NO: not cachable");
return 0;
}
if (EBIT_TEST(e->flags, KEY_PRIVATE)) {
debugs(71, 6, "storeDigestAddable: NO: private key");
return 0;
}
if (EBIT_TEST(e->flags, ENTRY_NEGCACHED)) {
debugs(71, 6, "storeDigestAddable: NO: negative cached");
return 0;
}
if (EBIT_TEST(e->flags, RELEASE_REQUEST)) {
debugs(71, 6, "storeDigestAddable: NO: release requested");
return 0;
}
if (e->store_status == STORE_OK && EBIT_TEST(e->flags, ENTRY_BAD_LENGTH)) {
debugs(71, 6, "storeDigestAddable: NO: wrong content-length");
return 0;
}
/* do not digest huge objects */
if (e->swap_file_sz > (uint64_t )Config.Store.maxObjectSize) {
debugs(71, 6, "storeDigestAddable: NO: too big");
return 0;
}
/* still here? check staleness */
/* Note: We should use the time of the next rebuild, not (cur_time+period) */
if (refreshCheckDigest(e, Config.digest.rebuild_period)) {
debugs(71, 6, "storeDigestAdd: entry expires within " << Config.digest.rebuild_period << " secs, ignoring");
return 0;
}
/*
* idea: how about also skipping very fresh (thus, potentially
* unstable) entries? Should be configurable through
* cd_refresh_pattern, of course.
*/
/*
* idea: skip objects that are going to be purged before the next
* update.
*/
return 1;
}
static void
storeDigestAdd(const StoreEntry * entry)
{
assert(entry && store_digest);
if (storeDigestAddable(entry)) {
++sd_stats.add_count;
if (cacheDigestTest(store_digest, (const cache_key *)entry->key))
++sd_stats.add_coll_count;
cacheDigestAdd(store_digest, (const cache_key *)entry->key);
debugs(71, 6, "storeDigestAdd: added entry, key: " << entry->getMD5Text());
} else {
++sd_stats.rej_count;
if (cacheDigestTest(store_digest, (const cache_key *)entry->key))
++sd_stats.rej_coll_count;
}
}
/* rebuilds digest from scratch */
static void
storeDigestRebuildStart(void *datanotused)
{
assert(store_digest);
/* prevent overlapping if rebuild schedule is too tight */
if (sd_state.rebuild_lock) {
debugs(71, DBG_IMPORTANT, "storeDigestRebuildStart: overlap detected, consider increasing rebuild period");
return;
}
sd_state.rebuild_lock = 1;
debugs(71, 2, "storeDigestRebuildStart: rebuild #" << sd_state.rebuild_count + 1);
if (sd_state.rewrite_lock) {
debugs(71, 2, "storeDigestRebuildStart: waiting for Rewrite to finish.");
return;
}
storeDigestRebuildResume();
}
/* called be Rewrite to push Rebuild forward */
static void
storeDigestRebuildResume(void)
{
assert(sd_state.rebuild_lock);
assert(!sd_state.rewrite_lock);
sd_state.theSearch = Store::Root().search(NULL, NULL);
/* resize or clear */
if (!storeDigestResize())
cacheDigestClear(store_digest); /* not clean()! */
memset(&sd_stats, 0, sizeof(sd_stats));
eventAdd("storeDigestRebuildStep", storeDigestRebuildStep, NULL, 0.0, 1);
}
/* finishes swap out sequence for the digest; schedules next rebuild */
static void
storeDigestRebuildFinish(void)
{
assert(sd_state.rebuild_lock);
sd_state.rebuild_lock = 0;
++sd_state.rebuild_count;
debugs(71, 2, "storeDigestRebuildFinish: done.");
eventAdd("storeDigestRebuildStart", storeDigestRebuildStart, NULL, (double)
Config.digest.rebuild_period, 1);
/* resume pending Rewrite if any */
if (sd_state.rewrite_lock)
storeDigestRewriteResume();
}
/* recalculate a few hash buckets per invocation; schedules next step */
static void
storeDigestRebuildStep(void *datanotused)
{
/* TODO: call Store::Root().size() to determine this.. */
int count = Config.Store.objectsPerBucket * (int) ceil((double) store_hash_buckets *
(double) Config.digest.rebuild_chunk_percentage / 100.0);
assert(sd_state.rebuild_lock);
debugs(71, 3, "storeDigestRebuildStep: buckets: " << store_hash_buckets << " entries to check: " << count);
while (count-- && !sd_state.theSearch->isDone() && sd_state.theSearch->next())
storeDigestAdd(sd_state.theSearch->currentItem());
/* are we done ? */
if (sd_state.theSearch->isDone())
storeDigestRebuildFinish();
else
eventAdd("storeDigestRebuildStep", storeDigestRebuildStep, NULL, 0.0, 1);
}
/* starts swap out sequence for the digest */
static void
storeDigestRewriteStart(void *datanotused)
{
RequestFlags flags;
char *url;
StoreEntry *e;
assert(store_digest);
/* prevent overlapping if rewrite schedule is too tight */
if (sd_state.rewrite_lock) {
debugs(71, DBG_IMPORTANT, "storeDigestRewrite: overlap detected, consider increasing rewrite period");
return;
}
debugs(71, 2, "storeDigestRewrite: start rewrite #" << sd_state.rewrite_count + 1);
/* make new store entry */
url = internalLocalUri("/squid-internal-periodic/", StoreDigestFileName);
flags.cachable = true;
e = storeCreateEntry(url, url, flags, Http::METHOD_GET);
assert(e);
sd_state.rewrite_lock = e;
debugs(71, 3, "storeDigestRewrite: url: " << url << " key: " << e->getMD5Text());
HttpRequest *req = HttpRequest::CreateFromUrl(url);
e->mem_obj->request = req;
HTTPMSGLOCK(e->mem_obj->request);
/* wait for rebuild (if any) to finish */
if (sd_state.rebuild_lock) {
debugs(71, 2, "storeDigestRewriteStart: waiting for rebuild to finish.");
return;
}
storeDigestRewriteResume();
}
static void
storeDigestRewriteResume(void)
{
StoreEntry *e;
assert(sd_state.rewrite_lock);
assert(!sd_state.rebuild_lock);
e = sd_state.rewrite_lock;
sd_state.rewrite_offset = 0;
EBIT_SET(e->flags, ENTRY_SPECIAL);
/* setting public key will purge old digest entry if any */
e->setPublicKey();
/* fake reply */
HttpReply *rep = new HttpReply;
rep->setHeaders(Http::scOkay, "Cache Digest OK",
"application/cache-digest", (store_digest->mask_size + sizeof(sd_state.cblock)),
squid_curtime, (squid_curtime + Config.digest.rewrite_period) );
debugs(71, 3, "storeDigestRewrite: entry expires on " << rep->expires <<
" (" << std::showpos << (int) (rep->expires - squid_curtime) << ")");
e->buffer();
e->replaceHttpReply(rep);
storeDigestCBlockSwapOut(e);
e->flush();
eventAdd("storeDigestSwapOutStep", storeDigestSwapOutStep, sd_state.rewrite_lock, 0.0, 1, false);
}
/* finishes swap out sequence for the digest; schedules next rewrite */
static void
storeDigestRewriteFinish(StoreEntry * e)
{
assert(e == sd_state.rewrite_lock);
e->complete();
e->timestampsSet();
debugs(71, 2, "storeDigestRewriteFinish: digest expires at " << e->expires <<
" (" << std::showpos << (int) (e->expires - squid_curtime) << ")");
/* is this the write order? @?@ */
e->mem_obj->unlinkRequest();
e->unlock();
sd_state.rewrite_lock = NULL;
++sd_state.rewrite_count;
eventAdd("storeDigestRewriteStart", storeDigestRewriteStart, NULL, (double)
Config.digest.rewrite_period, 1);
/* resume pending Rebuild if any */
if (sd_state.rebuild_lock)
storeDigestRebuildResume();
}
/* swaps out one digest "chunk" per invocation; schedules next swap out */
static void
storeDigestSwapOutStep(void *data)
{
StoreEntry *e = static_cast<StoreEntry *>(data);
int chunk_size = Config.digest.swapout_chunk_size;
assert(e == sd_state.rewrite_lock);
assert(e);
/* _add_ check that nothing bad happened while we were waiting @?@ @?@ */
if (sd_state.rewrite_offset + chunk_size > store_digest->mask_size)
chunk_size = store_digest->mask_size - sd_state.rewrite_offset;
e->append(store_digest->mask + sd_state.rewrite_offset, chunk_size);
debugs(71, 3, "storeDigestSwapOutStep: size: " << store_digest->mask_size <<
" offset: " << sd_state.rewrite_offset << " chunk: " <<
chunk_size << " bytes");
sd_state.rewrite_offset += chunk_size;
/* are we done ? */
if (sd_state.rewrite_offset >= store_digest->mask_size)
storeDigestRewriteFinish(e);
else
eventAdd("storeDigestSwapOutStep", storeDigestSwapOutStep, data, 0.0, 1, false);
}
static void
storeDigestCBlockSwapOut(StoreEntry * e)
{
memset(&sd_state.cblock, 0, sizeof(sd_state.cblock));
sd_state.cblock.ver.current = htons(CacheDigestVer.current);
sd_state.cblock.ver.required = htons(CacheDigestVer.required);
sd_state.cblock.capacity = htonl(store_digest->capacity);
sd_state.cblock.count = htonl(store_digest->count);
sd_state.cblock.del_count = htonl(store_digest->del_count);
sd_state.cblock.mask_size = htonl(store_digest->mask_size);
sd_state.cblock.bits_per_entry = (unsigned char)
Config.digest.bits_per_entry;
sd_state.cblock.hash_func_count = (unsigned char) CacheDigestHashFuncCount;
e->append((char *) &sd_state.cblock, sizeof(sd_state.cblock));
}
/* calculates digest capacity */
static int
storeDigestCalcCap(void)
{
/*
* To-Do: Bloom proved that the optimal filter utilization is 50% (half of
* the bits are off). However, we do not have a formula to calculate the
* number of _entries_ we want to pre-allocate for.
*/
const int hi_cap = Store::Root().maxSize() / Config.Store.avgObjectSize;
const int lo_cap = 1 + Store::Root().currentSize() / Config.Store.avgObjectSize;
const int e_count = StoreEntry::inUseCount();
int cap = e_count ? e_count :hi_cap;
debugs(71, 2, "storeDigestCalcCap: have: " << e_count << ", want " << cap <<
" entries; limits: [" << lo_cap << ", " << hi_cap << "]");
if (cap < lo_cap)
cap = lo_cap;
/* do not enforce hi_cap limit, average-based estimation may be wrong
*if (cap > hi_cap)
* cap = hi_cap;
*/
return cap;
}
/* returns true if we actually resized the digest */
static int
storeDigestResize(void)
{
const int cap = storeDigestCalcCap();
int diff;
assert(store_digest);
diff = abs(cap - store_digest->capacity);
debugs(71, 2, "storeDigestResize: " <<
store_digest->capacity << " -> " << cap << "; change: " <<
diff << " (" << xpercentInt(diff, store_digest->capacity) << "%)" );
/* avoid minor adjustments */
if (diff <= store_digest->capacity / 10) {
debugs(71, 2, "storeDigestResize: small change, will not resize.");
return 0;
} else {
debugs(71, 2, "storeDigestResize: big change, resizing.");
cacheDigestChangeCap(store_digest, cap);
return 1;
}
}
#endif /* USE_CACHE_DIGESTS */
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