LCOV - code coverage report
Current view: directory - netwerk/dns - nsHostResolver.h (source / functions) Found Hit Coverage
Test: app.info Lines: 5 5 100.0 %
Date: 2012-06-02 Functions: 7 7 100.0 %

       1                 : /* vim:set ts=4 sw=4 sts=4 et cin: */
       2                 : /* ***** BEGIN LICENSE BLOCK *****
       3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       4                 :  *
       5                 :  * The contents of this file are subject to the Mozilla Public License Version
       6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       7                 :  * the License. You may obtain a copy of the License at
       8                 :  * http://www.mozilla.org/MPL/
       9                 :  *
      10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12                 :  * for the specific language governing rights and limitations under the
      13                 :  * License.
      14                 :  *
      15                 :  * The Original Code is Mozilla.
      16                 :  *
      17                 :  * The Initial Developer of the Original Code is IBM Corporation.
      18                 :  * Portions created by IBM Corporation are Copyright (C) 2003
      19                 :  * IBM Corporation. All Rights Reserved.
      20                 :  *
      21                 :  * Contributor(s):
      22                 :  *   IBM Corp.
      23                 :  *
      24                 :  * Alternatively, the contents of this file may be used under the terms of
      25                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      26                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      27                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      28                 :  * of those above. If you wish to allow use of your version of this file only
      29                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      30                 :  * use your version of this file under the terms of the MPL, indicate your
      31                 :  * decision by deleting the provisions above and replace them with the notice
      32                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      33                 :  * the provisions above, a recipient may use your version of this file under
      34                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      35                 :  *
      36                 :  * ***** END LICENSE BLOCK ***** */
      37                 : 
      38                 : #ifndef nsHostResolver_h__
      39                 : #define nsHostResolver_h__
      40                 : 
      41                 : #include "nscore.h"
      42                 : #include "nsAtomicRefcnt.h"
      43                 : #include "prclist.h"
      44                 : #include "prnetdb.h"
      45                 : #include "pldhash.h"
      46                 : #include "mozilla/CondVar.h"
      47                 : #include "mozilla/Mutex.h"
      48                 : #include "nsISupportsImpl.h"
      49                 : #include "nsIDNSListener.h"
      50                 : #include "nsString.h"
      51                 : #include "nsTArray.h"
      52                 : 
      53                 : class nsHostResolver;
      54                 : class nsHostRecord;
      55                 : class nsResolveHostCallback;
      56                 : 
      57                 : /* XXX move this someplace more generic */
      58                 : #define NS_DECL_REFCOUNTED_THREADSAFE(classname)                             \
      59                 :   private:                                                                   \
      60                 :     nsAutoRefCnt _refc;                                                      \
      61                 :   public:                                                                    \
      62                 :     PRInt32 AddRef() {                                                       \
      63                 :         PRInt32 n = NS_AtomicIncrementRefcnt(_refc);                         \
      64                 :         NS_LOG_ADDREF(this, n, #classname, sizeof(classname));               \
      65                 :         return n;                                                            \
      66                 :     }                                                                        \
      67                 :     PRInt32 Release() {                                                      \
      68                 :         PRInt32 n = NS_AtomicDecrementRefcnt(_refc);                         \
      69                 :         NS_LOG_RELEASE(this, n, #classname);                                 \
      70                 :         if (n == 0)                                                          \
      71                 :             delete this;                                                     \
      72                 :         return n;                                                            \
      73                 :     }
      74                 : 
      75                 : #define MAX_RESOLVER_THREADS_FOR_ANY_PRIORITY  3
      76                 : #define MAX_RESOLVER_THREADS_FOR_HIGH_PRIORITY 5
      77                 : #define MAX_NON_PRIORITY_REQUESTS 150
      78                 : 
      79                 : #define MAX_RESOLVER_THREADS (MAX_RESOLVER_THREADS_FOR_ANY_PRIORITY + \
      80                 :                               MAX_RESOLVER_THREADS_FOR_HIGH_PRIORITY)
      81                 : 
      82                 : struct nsHostKey
      83             301 : {
      84                 :     const char *host;
      85                 :     PRUint16    flags;
      86                 :     PRUint16    af;
      87                 : };
      88                 : 
      89                 : /**
      90                 :  * nsHostRecord - ref counted object type stored in host resolver cache.
      91                 :  */
      92                 : class nsHostRecord : public PRCList, public nsHostKey
      93                 : {
      94                 :     typedef mozilla::Mutex Mutex;
      95                 : 
      96                 : public:
      97           39758 :     NS_DECL_REFCOUNTED_THREADSAFE(nsHostRecord)
      98                 : 
      99                 :     /* instantiates a new host record */
     100                 :     static nsresult Create(const nsHostKey *key, nsHostRecord **record);
     101                 : 
     102                 :     /* a fully resolved host record has either a non-null |addr_info| or |addr|
     103                 :      * field.  if |addr_info| is null, it implies that the |host| is an IP
     104                 :      * address literal.  in which case, |addr| contains the parsed address.
     105                 :      * otherwise, if |addr_info| is non-null, then it contains one or many
     106                 :      * IP addresses corresponding to the given host name.  if both |addr_info|
     107                 :      * and |addr| are null, then the given host has not yet been fully resolved.
     108                 :      * |af| is the address family of the record we are querying for.
     109                 :      */
     110                 : 
     111                 :     /* the lock protects |addr_info| and |addr_info_gencnt| because they
     112                 :      * are mutable and accessed by the resolver worker thread and the
     113                 :      * nsDNSService2 class.  |addr| doesn't change after it has been
     114                 :      * assigned a value.  only the resolver worker thread modifies
     115                 :      * nsHostRecord (and only in nsHostResolver::OnLookupComplete);
     116                 :      * the other threads just read it.  therefore the resolver worker
     117                 :      * thread doesn't need to lock when reading |addr_info|.
     118                 :      */
     119                 :     Mutex        addr_info_lock;
     120                 :     int          addr_info_gencnt; /* generation count of |addr_info| */
     121                 :     PRAddrInfo  *addr_info;
     122                 :     PRNetAddr   *addr;
     123                 :     bool         negative;   /* True if this record is a cache of a failed lookup.
     124                 :                                 Negative cache entries are valid just like any other
     125                 :                                 (though never for more than 60 seconds), but a use
     126                 :                                 of that negative entry forces an asynchronous refresh. */
     127                 : 
     128                 :     PRUint32     expiration; /* measured in minutes since epoch */
     129                 : 
     130            4570 :     bool HasResult() const { return addr_info || addr || negative; }
     131                 : 
     132                 :     // hold addr_info_lock when calling the blacklist functions
     133                 :     bool Blacklisted(PRNetAddr *query);
     134                 :     void   ResetBlacklist();
     135                 :     void   ReportUnusable(PRNetAddr *addr);
     136                 : 
     137                 : private:
     138                 :     friend class nsHostResolver;
     139                 : 
     140                 :     PRCList callbacks; /* list of callbacks */
     141                 : 
     142                 :     bool    resolving; /* true if this record is being resolved, which means
     143                 :                         * that it is either on the pending queue or owned by
     144                 :                         * one of the worker threads. */ 
     145                 :     
     146                 :     bool    onQueue;  /* true if pending and on the queue (not yet given to getaddrinfo())*/
     147                 :     bool    usingAnyThread; /* true if off queue and contributing to mActiveAnyThreadCount */
     148                 : 
     149                 :     // a list of addresses associated with this record that have been reported
     150                 :     // as unusable. the list is kept as a set of strings to make it independent
     151                 :     // of gencnt.
     152                 :     nsTArray<nsCString> mBlacklistedItems;
     153                 : 
     154                 :     nsHostRecord(const nsHostKey *key);           /* use Create() instead */
     155                 :    ~nsHostRecord();
     156                 : };
     157                 : 
     158                 : /**
     159                 :  * ResolveHost callback object.  It's PRCList members are used by
     160                 :  * the nsHostResolver and should not be used by anything else.
     161                 :  */
     162                 : class NS_NO_VTABLE nsResolveHostCallback : public PRCList
     163            6493 : {
     164                 : public:
     165                 :     /**
     166                 :      * OnLookupComplete
     167                 :      * 
     168                 :      * this function is called to complete a host lookup initiated by
     169                 :      * nsHostResolver::ResolveHost.  it may be invoked recursively from
     170                 :      * ResolveHost or on an unspecified background thread.
     171                 :      * 
     172                 :      * NOTE: it is the responsibility of the implementor of this method
     173                 :      * to handle the callback in a thread safe manner.
     174                 :      *
     175                 :      * @param resolver
     176                 :      *        nsHostResolver object associated with this result
     177                 :      * @param record
     178                 :      *        the host record containing the results of the lookup
     179                 :      * @param status
     180                 :      *        if successful, |record| contains non-null results
     181                 :      */
     182                 :     virtual void OnLookupComplete(nsHostResolver *resolver,
     183                 :                                   nsHostRecord   *record,
     184                 :                                   nsresult        status) = 0;
     185                 :     /**
     186                 :      * EqualsAsyncListener
     187                 :      *
     188                 :      * Determines if the listener argument matches the listener member var.
     189                 :      * For subclasses not implementing a member listener, should return false.
     190                 :      * For subclasses having a member listener, the function should check if
     191                 :      * they are the same.  Used for cases where a pointer to an object
     192                 :      * implementing nsResolveHostCallback is unknown, but a pointer to
     193                 :      * the original listener is known.
     194                 :      *
     195                 :      * @param aListener
     196                 :      *        nsIDNSListener object associated with the original request
     197                 :      */
     198                 :     virtual bool EqualsAsyncListener(nsIDNSListener *aListener) = 0;
     199                 : };
     200                 : 
     201                 : /**
     202                 :  * nsHostResolver - an asynchronous host name resolver.
     203                 :  */
     204                 : class nsHostResolver
     205                 : {
     206                 :     typedef mozilla::CondVar CondVar;
     207                 :     typedef mozilla::Mutex Mutex;
     208                 : 
     209                 : public:
     210                 :     /**
     211                 :      * host resolver instances are reference counted.
     212                 :      */
     213           52769 :     NS_DECL_REFCOUNTED_THREADSAFE(nsHostResolver)
     214                 : 
     215                 :     /**
     216                 :      * creates an addref'd instance of a nsHostResolver object.
     217                 :      */
     218                 :     static nsresult Create(PRUint32         maxCacheEntries,  // zero disables cache
     219                 :                            PRUint32         maxCacheLifetime, // minutes
     220                 :                            PRUint32         lifetimeGracePeriod, // minutes
     221                 :                            nsHostResolver **resolver);
     222                 :     
     223                 :     /**
     224                 :      * puts the resolver in the shutdown state, which will cause any pending
     225                 :      * callbacks to be detached.  any future calls to ResolveHost will fail.
     226                 :      */
     227                 :     void Shutdown();
     228                 : 
     229                 :     /**
     230                 :      * resolve the given hostname asynchronously.  the caller can synthesize
     231                 :      * a synchronous host lookup using a lock and a cvar.  as noted above
     232                 :      * the callback will occur re-entrantly from an unspecified thread.  the
     233                 :      * host lookup cannot be canceled (cancelation can be layered above this
     234                 :      * by having the callback implementation return without doing anything).
     235                 :      */
     236                 :     nsresult ResolveHost(const char            *hostname,
     237                 :                          PRUint16               flags,
     238                 :                          PRUint16               af,
     239                 :                          nsResolveHostCallback *callback);
     240                 : 
     241                 :     /**
     242                 :      * removes the specified callback from the nsHostRecord for the given
     243                 :      * hostname, flags, and address family.  these parameters should correspond
     244                 :      * to the parameters passed to ResolveHost.  this function executes the
     245                 :      * callback if the callback is still pending with the given status.
     246                 :      */
     247                 :     void DetachCallback(const char            *hostname,
     248                 :                         PRUint16               flags,
     249                 :                         PRUint16               af,
     250                 :                         nsResolveHostCallback *callback,
     251                 :                         nsresult               status);
     252                 : 
     253                 :     /**
     254                 :      * Cancels an async request associated with the hostname, flags,
     255                 :      * address family and listener.  Cancels first callback found which matches
     256                 :      * these criteria.  These parameters should correspond to the parameters
     257                 :      * passed to ResolveHost.  If this is the last callback associated with the
     258                 :      * host record, it is removed from any request queues it might be on. 
     259                 :      */
     260                 :     void CancelAsyncRequest(const char            *host,
     261                 :                             PRUint16               flags,
     262                 :                             PRUint16               af,
     263                 :                             nsIDNSListener        *aListener,
     264                 :                             nsresult               status);
     265                 :     /**
     266                 :      * values for the flags parameter passed to ResolveHost and DetachCallback
     267                 :      * that may be bitwise OR'd together.
     268                 :      *
     269                 :      * NOTE: in this implementation, these flags correspond exactly in value
     270                 :      *       to the flags defined on nsIDNSService.
     271                 :      */
     272                 :     enum {
     273                 :         RES_BYPASS_CACHE = 1 << 0,
     274                 :         RES_CANON_NAME   = 1 << 1,
     275                 :         RES_PRIORITY_MEDIUM   = 1 << 2,
     276                 :         RES_PRIORITY_LOW  = 1 << 3,
     277                 :         RES_SPECULATE     = 1 << 4   
     278                 :     };
     279                 : 
     280                 : private:
     281                 :     nsHostResolver(PRUint32 maxCacheEntries = 50, PRUint32 maxCacheLifetime = 1,
     282                 :                    PRUint32 lifetimeGracePeriod = 0);
     283                 :    ~nsHostResolver();
     284                 : 
     285                 :     nsresult Init();
     286                 :     nsresult IssueLookup(nsHostRecord *);
     287                 :     bool     GetHostToLookup(nsHostRecord **m);
     288                 :     void     OnLookupComplete(nsHostRecord *, nsresult, PRAddrInfo *);
     289                 :     void     DeQueue(PRCList &aQ, nsHostRecord **aResult);
     290                 :     void     ClearPendingQueue(PRCList *aPendingQueue);
     291                 :     nsresult ConditionallyCreateThread(nsHostRecord *rec);
     292                 :     
     293                 :     static void  MoveQueue(nsHostRecord *aRec, PRCList &aDestQ);
     294                 :     
     295                 :     static void ThreadFunc(void *);
     296                 : 
     297                 :     enum {
     298                 :         METHOD_HIT = 1,
     299                 :         METHOD_RENEWAL = 2,
     300                 :         METHOD_NEGATIVE_HIT = 3,
     301                 :         METHOD_LITERAL = 4,
     302                 :         METHOD_OVERFLOW = 5,
     303                 :         METHOD_NETWORK_FIRST = 6,
     304                 :         METHOD_NETWORK_SHARED = 7
     305                 :     };
     306                 : 
     307                 :     PRUint32      mMaxCacheEntries;
     308                 :     PRUint32      mMaxCacheLifetime;
     309                 :     PRUint32      mGracePeriod;
     310                 :     Mutex         mLock;
     311                 :     CondVar       mIdleThreadCV;
     312                 :     PRUint32      mNumIdleThreads;
     313                 :     PRUint32      mThreadCount;
     314                 :     PRUint32      mActiveAnyThreadCount;
     315                 :     PLDHashTable  mDB;
     316                 :     PRCList       mHighQ;
     317                 :     PRCList       mMediumQ;
     318                 :     PRCList       mLowQ;
     319                 :     PRCList       mEvictionQ;
     320                 :     PRUint32      mEvictionQSize;
     321                 :     PRUint32      mPendingCount;
     322                 :     PRTime        mCreationTime;
     323                 :     bool          mShutdown;
     324                 :     PRIntervalTime mLongIdleTimeout;
     325                 :     PRIntervalTime mShortIdleTimeout;
     326                 : };
     327                 : 
     328                 : #endif // nsHostResolver_h__

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