FQDN Cache Internals

Collaboration diagram for FQDN Cache Internals:

Classes
struct	_fqdn_cache_stats

Macros
#define	FQDN_LOW_WATER   90
#define	FQDN_HIGH_WATER   95

Functions
int	fqdncacheCount ()
static void	fqdncacheRelease (fqdncache_entry *)
static fqdncache_entry *	fqdncache_get (const char *)
static int	fqdncacheExpiredEntry (const fqdncache_entry *f)
static void	fqdncacheAddEntry (fqdncache_entry *f)
static void	fqdncacheCallback (fqdncache_entry *, int wait)
static int	fqdncacheParse (fqdncache_entry *f, const rfc1035_rr *answers, int nr, const char *error_message)
void	fqdnStats (StoreEntry *sentry)
static void	fqdncacheLockEntry (fqdncache_entry *f)
static void	fqdncacheUnlockEntry (fqdncache_entry *f)
static void	fqdncacheRegisterWithCacheManager (void)

Variables
static struct _fqdn_cache_stats	FqdncacheStats
static dlink_list	lru_list
static hash_table *	fqdn_table = nullptr
static long	fqdncache_low = 180
static long	fqdncache_high = 200

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.

Macro Definition Documentation

FQDN_HIGH_WATER

#define FQDN_HIGH_WATER   95

Definition at line 71 of file fqdncache.cc.

FQDN_LOW_WATER

#define FQDN_LOW_WATER   90

Definition at line 68 of file fqdncache.cc.

Function Documentation

fqdncache_get()

static fqdncache_entry * fqdncache_get ( const char *  name )

static

Parameters

name	FQDN hash string.

Return values

Match

for given name

Definition at line 169 of file fqdncache.cc.

References fqdn_table, and hash_lookup().

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

fqdncacheAddEntry()

static void fqdncacheAddEntry ( fqdncache_entry *  f )

static

Definition at line 270 of file fqdncache.cc.

References dlinkAdd(), fqdn_table, fqdncacheRelease(), fqdncache_entry::hash, hash_join(), hash_lookup(), hash_link::key, fqdncache_entry::lastref, fqdncache_entry::lru, lru_list, and squid_curtime.

Referenced by fqdncacheAddEntryFromHosts(), and fqdncacheHandleReply().

fqdncacheCallback()

static void fqdncacheCallback ( fqdncache_entry *  f, int  wait  )

static

Walks down the pending list, calling handlers

Definition at line 291 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, and squid_curtime.

Referenced by fqdncache_nbgethostbyaddr(), and fqdncacheHandleReply().

fqdncacheCount()

int fqdncacheCount ( )

inline

Definition at line 142 of file fqdncache.cc.

References hash_table::count, and fqdn_table.

Referenced by fqdncache_purgelru(), fqdnStats(), and snmp_netFqdnFn().

fqdncacheExpiredEntry()

static int fqdncacheExpiredEntry ( const fqdncache_entry *  f )

static

Definition at line 185 of file fqdncache.cc.

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

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

fqdncacheLockEntry()

static void fqdncacheLockEntry ( fqdncache_entry *  f )

static

Definition at line 584 of file fqdncache.cc.

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

Referenced by fqdncacheAddEntryFromHosts(), and fqdncacheCallback().

fqdncacheParse()

static int fqdncacheParse ( fqdncache_entry *  f, const rfc1035_rr *  answers, int  nr, const char *  error_message  )

static

Definition at line 316 of file fqdncache.cc.

References assert, Config, DBG_IMPORTANT, debugs, fqdncache_entry::error_message, fqdncache_entry::expires, fqdncache_entry::flags, FQDN_MAX_NAMES, fqdncache_entry::hash, hash_link::key, fqdncache_entry::name_count, fqdncache_entry::names, SquidConfig::negativeDnsTtl, fqdncache_entry::Flags::negcached, SquidConfig::positiveDnsTtl, RFC1035_CLASS_IN, RFC1035_TYPE_CNAME, RFC1035_TYPE_PTR, squid_curtime, rfc1035_rr::ttl, and xstrdup.

Referenced by fqdncacheHandleReply().

fqdncacheRegisterWithCacheManager()

static void fqdncacheRegisterWithCacheManager ( void  )

static

Definition at line 671 of file fqdncache.cc.

References fqdnStats(), and Mgr::RegisterAction().

Referenced by fqdncache_init().

fqdncacheRelease()

static void fqdncacheRelease ( fqdncache_entry *  f )

static

Removes the given fqdncache entry

Definition at line 155 of file fqdncache.cc.

References debugs, dlinkDelete(), fqdn_table, fqdncache_entry::hash, hash_remove_link(), hashKeyStr(), fqdncache_entry::lru, and lru_list.

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

fqdncacheUnlockEntry()

static void fqdncacheUnlockEntry ( fqdncache_entry *  f )

static

Definition at line 594 of file fqdncache.cc.

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

Referenced by fqdncacheAddEntryFromHosts(), and fqdncacheCallback().

fqdnStats()

void fqdnStats

(

StoreEntry *

sentry

)

Process objects list

Definition at line 530 of file fqdncache.cc.

References fqdncache_entry::expires, fqdncache_entry::flags, fqdn_table, fqdncacheCount(), FqdncacheStats, fqdncache_entry::Flags::fromhosts, fqdncache_entry::hash, hash_first(), hash_next(), hashKeyStr(), _fqdn_cache_stats::hits, int, _fqdn_cache_stats::misses, fqdncache_entry::name_count, fqdncache_entry::names, _fqdn_cache_stats::negative_hits, fqdncache_entry::Flags::negcached, _fqdn_cache_stats::requests, squid_curtime, and storeAppendPrintf().

Referenced by fqdncacheRegisterWithCacheManager().

Variable Documentation

fqdn_table

hash_table* fqdn_table = nullptr

static

Definition at line 133 of file fqdncache.cc.

Referenced by fqdncache_get(), fqdncache_init(), fqdncacheAddEntry(), fqdncacheCount(), fqdncacheRelease(), and fqdnStats().

fqdncache_high

long fqdncache_high = 200

static

Definition at line 139 of file fqdncache.cc.

Referenced by fqdncache_init(), and fqdncache_restart().

fqdncache_low

long fqdncache_low = 180

static

Definition at line 136 of file fqdncache.cc.

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

FqdncacheStats

struct _fqdn_cache_stats FqdncacheStats

static

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

lru_list

dlink_list lru_list

static

Definition at line 120 of file fqdncache.cc.

Referenced by fqdncache_init(), fqdncache_purgelru(), fqdncacheAddEntry(), fqdncacheLockEntry(), fqdncacheRelease(), and purge_entries_fromhosts().