IP Cache Internals

Collaboration diagram for IP Cache Internals:

Classes
struct	_ipcache_stats

Functions
int	ipcacheCount ()
static void	ipcacheRelease (ipcache_entry *, bool dofree=true)
static ipcache_entry *	ipcache_get (const char *name)
static int	ipcacheExpiredEntry (ipcache_entry *i)
static void	purge_entries_fromhosts (void)
static void	ipcacheAddEntry (ipcache_entry *i)
static void	ipcacheCallback (ipcache_entry *i, const bool hit, const int wait)
static void	ipcacheHandleReply (void *data, const rfc1035_rr *answers, int na, const char *error_message, const bool lastAnswer)
static void	ipcacheRegisterWithCacheManager (void)
static void	ipcacheStatPrint (ipcache_entry *i, StoreEntry *sentry)
static void	stat_ipcache_get (StoreEntry *)
static void	ipcacheLockEntry (ipcache_entry *i)
static void	ipcacheUnlockEntry (ipcache_entry *i)
static void	ipcacheFreeEntry (void *data)

Variables
static struct _ipcache_stats	IpcacheStats
static dlink_list	lru_list
static hash_table *	ip_table = nullptr
static long	ipcache_low = 180
static long	ipcache_high = 200

Detailed Description

Note

when IP cache is provided as a class. These sub-groups will be obsolete for now they are used to separate the public and private functions. with the private ones all being in IPCachInternal and public in IPCacheAPI

Internal Operation

Internally, the execution flow is as follows: On a miss, ipcache_getnbhostbyname checks whether a request for this name is already pending, and if positive, it creates a new entry using ipcacheAddNew with the IP_PENDING flag set . Then it calls ipcacheAddPending to add a request to the queue together with data and handler. Else, ipcache_dnsDispatch() is called to directly create a DNS query or to ipcacheEnqueue() if all no DNS port is free. ipcache_call_pending() is called regularly to walk down the pending list and call handlers. LRU clean-up is performed through ipcache_purgelru() according to the ipcache_high threshold.

Function Documentation

ipcache_get()

static ipcache_entry * ipcache_get ( const char *  name )

static

Definition at line 324 of file ipcache.cc.

References hash_lookup(), and ip_table.

Referenced by ipcache_gethostbyname(), ipcache_nbgethostbyname_(), ipcacheAddEntryFromHosts(), ipcacheInvalidate(), ipcacheInvalidateNegative(), ipcacheMarkBadAddr(), and ipcacheMarkGoodAddr().

ipcacheAddEntry()

static void ipcacheAddEntry ( ipcache_entry *  i )

static

Definition at line 422 of file ipcache.cc.

References dlinkAdd(), ipcache_entry::hash, hash_join(), hash_lookup(), ip_table, ipcacheRelease(), hash_link::key, ipcache_entry::lastref, ipcache_entry::lru, lru_list, and squid_curtime.

Referenced by ipcacheAddEntryFromHosts(), and ipcacheHandleReply().

ipcacheCallback()

static void ipcacheCallback ( ipcache_entry *  i, const bool  hit, const int  wait  )

static

walks down the pending list, calling handlers

Definition at line 443 of file ipcache.cc.

References ipcache_entry::addrs, ipcache_entry::error_message, IpCacheLookupForwarder::finalCallback(), IpCacheLookupForwarder::forwardHits(), ipcache_entry::handler, ipcacheLockEntry(), ipcacheUnlockEntry(), ipcache_entry::lastref, and squid_curtime.

Referenced by ipcache_nbgethostbyname_(), and ipcacheHandleReply().

ipcacheCount()

int ipcacheCount ( )

inline

Definition at line 294 of file ipcache.cc.

References hash_table::count, and ip_table.

Referenced by ipcache_purgelru(), snmp_netIpFn(), and stat_ipcache_get().

ipcacheExpiredEntry()

static int ipcacheExpiredEntry ( ipcache_entry *  i )

static

Definition at line 334 of file ipcache.cc.

References ipcache_entry::addrs, Dns::CachedIps::empty(), ipcache_entry::expires, ipcache_entry::flags, ipcache_entry::locks, ipcache_entry::Flags::negcached, and squid_curtime.

Referenced by ipcache_gethostbyname(), ipcache_nbgethostbyname_(), and ipcacheUnlockEntry().

ipcacheFreeEntry()

static void ipcacheFreeEntry ( void *  data )

static

Definition at line 1085 of file ipcache.cc.

ipcacheHandleReply()

static void ipcacheHandleReply ( void *  data, const rfc1035_rr *  answers, int  na, const char *  error_message, const bool  lastAnswer  )

static

Definition at line 562 of file ipcache.cc.

References ipcache_entry::addrs, _ipcache_stats::cname_only, Config, StatHist::count(), debugs, StatCounters::dns, Dns::CachedIps::empty(), ipcache_entry::error_message, ipcache_entry::expires, ipcache_entry::flags, IpCacheLookupForwarder::forwardLookup(), ipcache_entry::handler, ipcacheAddEntry(), ipcacheCallback(), ipcacheParse(), IpcacheStats, ipcache_entry::latestError(), ipcache_entry::name(), SquidConfig::negativeDnsTtl, ipcache_entry::Flags::negcached, _ipcache_stats::replies, ipcache_entry::sawCname, squid_curtime, statCounter, StatCounters::svcTime, and IpCacheLookupForwarder::totalResponseTime().

ipcacheLockEntry()

static void ipcacheLockEntry ( ipcache_entry *  i )

static

Definition at line 914 of file ipcache.cc.

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

Referenced by ipcacheAddEntryFromHosts(), and ipcacheCallback().

ipcacheRegisterWithCacheManager()

static void ipcacheRegisterWithCacheManager ( void  )

static

Definition at line 681 of file ipcache.cc.

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

Referenced by ipcache_init().

ipcacheRelease()

static void ipcacheRelease ( ipcache_entry *  i, bool  dofree  )

static

removes the given ipcache entry

Definition at line 302 of file ipcache.cc.

References DBG_CRITICAL, debugs, dlinkDelete(), ipcache_entry::hash, hash_remove_link(), ip_table, ipcacheFreeEntry, hash_link::key, ipcache_entry::lru, and lru_list.

Referenced by ipcache_gethostbyname(), ipcache_nbgethostbyname_(), ipcache_purgelru(), ipcacheAddEntry(), ipcacheAddEntryFromHosts(), ipcacheUnlockEntry(), and purge_entries_fromhosts().

ipcacheStatPrint()

static void ipcacheStatPrint ( ipcache_entry *  i, StoreEntry *  sentry  )

static

Negative-cached entries have no IPs listed.

Cached entries have IPs listed with a BNF of: ip-address '-' ('OK'|'BAD')

Definition at line 770 of file ipcache.cc.

References ipcache_entry::addrs, Dns::CachedIps::badCount(), DBG_CRITICAL, debugs, ipcache_entry::expires, ipcache_entry::flags, ipcache_entry::Flags::fromhosts, ipcache_entry::hash, hashKeyStr(), int, ipcache_entry::lastref, MAX_IPSTRLEN, ipcache_entry::Flags::negcached, Dns::CachedIps::raw(), Dns::CachedIps::size(), squid_curtime, and storeAppendPrintf().

Referenced by stat_ipcache_get().

ipcacheUnlockEntry()

static void ipcacheUnlockEntry ( ipcache_entry *  i )

static

Definition at line 924 of file ipcache.cc.

References DBG_IMPORTANT, debugs, ipcacheExpiredEntry(), ipcacheRelease(), and ipcache_entry::locks.

Referenced by ipcacheAddEntryFromHosts(), and ipcacheCallback().

purge_entries_fromhosts()

static void purge_entries_fromhosts ( void  )

static

purges entries added from /etc/hosts (or whatever).

Definition at line 386 of file ipcache.cc.

References dlink_node::data, dlink_list::head, ipcacheRelease(), lru_list, and dlink_node::next.

stat_ipcache_get()

void stat_ipcache_get ( StoreEntry *  sentry )

static

process objects list

Definition at line 821 of file ipcache.cc.

References assert, _ipcache_stats::cname_only, dlink_node::data, dlink_list::head, _ipcache_stats::hits, _ipcache_stats::invalid, ip_table, ipcacheCount(), ipcacheStatPrint(), IpcacheStats, lru_list, _ipcache_stats::misses, _ipcache_stats::negative_hits, dlink_node::next, _ipcache_stats::numeric_hits, _ipcache_stats::requests, _ipcache_stats::rr_a, _ipcache_stats::rr_aaaa, _ipcache_stats::rr_cname, and storeAppendPrintf().

Referenced by ipcacheRegisterWithCacheManager().

Variable Documentation

ip_table

hash_table* ip_table = nullptr

static

Definition at line 207 of file ipcache.cc.

Referenced by ipcache_get(), ipcache_init(), ipcacheAddEntry(), ipcacheCount(), ipcacheRelease(), and stat_ipcache_get().

ipcache_high

long ipcache_high = 200

static

Definition at line 212 of file ipcache.cc.

Referenced by ipcache_init(), and ipcache_restart().

ipcache_low

long ipcache_low = 180

static

Definition at line 210 of file ipcache.cc.

Referenced by ipcache_init(), ipcache_purgelru(), and ipcache_restart().

IpcacheStats

struct _ipcache_stats IpcacheStats

static

Referenced by ipcache_gethostbyname(), ipcache_init(), ipcache_nbgethostbyname_(), ipcacheHandleReply(), ipcacheParse(), snmp_netIpFn(), and stat_ipcache_get().

lru_list

dlink_list lru_list

static

Definition at line 190 of file ipcache.cc.

Referenced by ipcache_init(), ipcache_purgelru(), ipcacheAddEntry(), ipcacheLockEntry(), ipcacheRelease(), purge_entries_fromhosts(), and stat_ipcache_get().