FQDN Cache Internals
[FQDN Cache API]

Collaboration diagram for FQDN Cache Internals:

Classes
struct	_fqdn_cache_stats
Defines
#define	FQDN_LOW_WATER   90
#define	FQDN_HIGH_WATER   95
Functions
static void	fqdncacheRelease (fqdncache_entry *)
static fqdncache_entry *	fqdncache_get (const char *)
static int	fqdncacheExpiredEntry (const fqdncache_entry *f)
static fqdncache_entry *	fqdncacheCreateEntry (const char *name)
static void	fqdncacheAddEntry (fqdncache_entry *f)
static void	fqdncacheCallback (fqdncache_entry *, int wait)
static int	fqdncacheParse (fqdncache_entry *f, const char *inbuf)
static void	fqdncacheRegisterWithCacheManager (void)
void	fqdnStats (StoreEntry *sentry)
static void	fqdncacheLockEntry (fqdncache_entry *f)
static void	fqdncacheUnlockEntry (fqdncache_entry *f)
static void	fqdncacheFreeEntry (void *data)
Variables
static struct _fqdn_cache_stats	FqdncacheStats
static dlink_list	lru_list
static hash_table *	fqdn_table = NULL
static long	fqdncache_low = 180
static long	fqdncache_high = 200

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Detailed Description

Internally, the execution flow is as follows: On a miss, fqdncache_nbgethostbyaddr() checks whether a request for this name is already pending, and if positive, it creates a new entry using fqdncacheAddEntry(). Then it calls fqdncacheAddPending() to add a request to the queue together with data and handler. Else, ifqdncache_dnsDispatch() is called to directly create a DNS query or to fqdncacheEnqueue() if all no DNS port is free.

fqdncacheCallback() is called regularly to walk down the pending list and call handlers.

LRU clean-up is performed through fqdncache_purgelru() according to the fqdncache_high threshold.

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Define Documentation

#define FQDN_HIGH_WATER   95

Definition at line 84 of file fqdncache.cc.

Referenced by fqdncache_init(), and fqdncache_restart().

#define FQDN_LOW_WATER   90

Definition at line 81 of file fqdncache.cc.

Referenced by fqdncache_init(), and fqdncache_restart().

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Function Documentation

static fqdncache_entry * fqdncache_get

(

const char *

name

)

[static]

Parameters:

name

FQDN hash string.

Return values:

Match

for given name

Definition at line 192 of file fqdncache.cc.

References hash_lookup(), and NULL.

Referenced by fqdncache_gethostbyaddr(), fqdncache_nbgethostbyaddr(), and fqdncacheAddEntryFromHosts().

static void fqdncacheAddEntry

(

fqdncache_entry *

f

)

[static]

Definition at line 293 of file fqdncache.cc.

References dlinkAdd(), fqdncacheRelease(), fqdncache_entry::hash, hash_join(), hash_lookup(), _hash_link::key, fqdncache_entry::lastref, fqdncache_entry::lru, NULL, and squid_curtime.

Referenced by fqdncacheAddEntryFromHosts(), and fqdncacheHandleReply().

static void fqdncacheCallback	(	fqdncache_entry *	f,
		int	wait
	)			[static]

Walks down the pending list, calling handlers

Definition at line 314 of file fqdncache.cc.

References cbdataReferenceValidDone, fqdncache_entry::error_message, fqdncacheLockEntry(), fqdncacheUnlockEntry(), fqdncache_entry::handler, fqdncache_entry::handlerData, fqdncache_entry::lastref, fqdncache_entry::name_count, fqdncache_entry::names, NULL, and squid_curtime.

Referenced by fqdncache_nbgethostbyaddr(), and fqdncacheHandleReply().

static fqdncache_entry * fqdncacheCreateEntry

(

const char *

name

)

[static]

Create blank fqdncache_entry

Definition at line 282 of file fqdncache.cc.

References Config, fqdncache_entry::expires, fqdncache_entry::hash, _hash_link::key, MEM_FQDNCACHE_ENTRY, memAllocate(), SquidConfig::negativeDnsTtl, squid_curtime, and xstrdup().

Referenced by fqdncache_nbgethostbyaddr(), and fqdncacheAddEntryFromHosts().

static int fqdncacheExpiredEntry

(

const fqdncache_entry *

f

)

[static]

Definition at line 208 of file fqdncache.cc.

References fqdncache_entry::expires, fqdncache_entry::locks, and squid_curtime.

Referenced by fqdncache_gethostbyaddr(), fqdncache_nbgethostbyaddr(), and fqdncacheUnlockEntry().

static void fqdncacheFreeEntry

(

void *

data

)

[static]

Definition at line 780 of file fqdncache.cc.

References fqdncache_entry::error_message, fqdncache_entry::hash, _hash_link::key, MEM_FQDNCACHE_ENTRY, memFree(), fqdncache_entry::name_count, fqdncache_entry::names, and safe_free.

static void fqdncacheLockEntry

(

fqdncache_entry *

f

)

[static]

Definition at line 759 of file fqdncache.cc.

References dlinkAdd(), dlinkDelete(), fqdncache_entry::locks, and fqdncache_entry::lru.

Referenced by fqdncacheAddEntryFromHosts(), and fqdncacheCallback().

static int fqdncacheParse	(	fqdncache_entry *	f,
		const char *	buf
	)			[static]

Definition at line 340 of file fqdncache.cc.

References assert, Config, debugs, DNS_INBUF_SZ, fqdncache_entry::error_message, fqdncache_entry::expires, fqdncache_entry::flags, fqdncache_entry::hash, _hash_link::key, LOCAL_ARRAY, name, fqdncache_entry::name_count, fqdncache_entry::names, SquidConfig::negativeDnsTtl, fqdncache_entry::negcached, NULL, SquidConfig::positiveDnsTtl, squid_curtime, w_space, xstrdup(), and xstrncpy().

Referenced by fqdncacheHandleReply().

static void fqdncacheRegisterWithCacheManager

(

void

)

[static]

Definition at line 587 of file fqdncache.cc.

References fqdnStats(), and CacheManager::GetInstance().

Referenced by fqdncache_init().

static void fqdncacheRelease

(

fqdncache_entry *

f

)

[static]

Removes the given fqdncache entry

Definition at line 167 of file fqdncache.cc.

References debugs, dlinkDelete(), hash_remove_link(), hashKeyStr(), _hash_link::key, MEM_FQDNCACHE_ENTRY, memFree(), and safe_free.

Referenced by fqdncache_gethostbyaddr(), fqdncache_nbgethostbyaddr(), fqdncache_purgelru(), fqdncacheAddEntry(), fqdncacheAddEntryFromHosts(), fqdncacheUnlockEntry(), and purge_entries_fromhosts().

static void fqdncacheUnlockEntry

(

fqdncache_entry *

f

)

[static]

Definition at line 769 of file fqdncache.cc.

References assert, fqdncacheExpiredEntry(), fqdncacheRelease(), and fqdncache_entry::locks.

Referenced by fqdncacheAddEntryFromHosts(), and fqdncacheCallback().

void fqdnStats

(

StoreEntry *

sentry

)

Process objects list

Definition at line 691 of file fqdncache.cc.

References fqdncache_entry::expires, fqdncache_entry::flags, FqdncacheStats, fqdncache_entry::fromhosts, fqdncache_entry::hash, hash_first(), hash_next(), hashKeyStr(), _fqdn_cache_stats::hits, MEM_FQDNCACHE_ENTRY, memInUse(), _fqdn_cache_stats::misses, fqdncache_entry::name_count, fqdncache_entry::names, _fqdn_cache_stats::negative_hits, fqdncache_entry::negcached, NULL, _fqdn_cache_stats::requests, squid_curtime, and storeAppendPrintf().

Referenced by fqdncacheRegisterWithCacheManager().

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Variable Documentation

hash_table* fqdn_table = NULL [static]

Definition at line 147 of file fqdncache.cc.

long fqdncache_high = 200 [static]

Definition at line 153 of file fqdncache.cc.

Referenced by fqdncache_init(), and fqdncache_restart().

long fqdncache_low = 180 [static]

Definition at line 150 of file fqdncache.cc.

Referenced by fqdncache_init(), fqdncache_purgelru(), and fqdncache_restart().

struct _fqdn_cache_stats FqdncacheStats [static]

Referenced by fqdncache_gethostbyaddr(), fqdncache_init(), fqdncache_nbgethostbyaddr(), fqdncacheHandleReply(), fqdnStats(), and snmp_netFqdnFn().

dlink_list lru_list [static]

Definition at line 127 of file fqdncache.cc.

Referenced by external_acl::add().