Re: [naviserver-devel] Re: [naviserver-commits] naviserver/nsd tclcache.c,1.2,1.3 tclcmds.c,1.34,1.35

[Vlad S. <vl...@cr...>]

Yes, i use cache and in my case i do need to use get and set in 
different situations, for example i need to set cache entry regardless 
of what is there, eval will return me existing value, so i need to flush 
it first which gets to the same race condition issue.
Same with get, i just need to get value if it exists without issuing 
exists first and then eval, if it is not there i do not want to set it, 
eval will set it.


Stephen Deasey wrote:
> What's the use case for these commands?  I looked at the existing
> usage in e.g. ACS back when I added this and it seems that people are
> calling _get, and if it's not there, then calling _set.  But this
> looks like a race condition to me.
> 
> Does _eval not cover everything?
> 
> 
> 
> On 4/5/06, Vlad Seryakov <ser...@us...> wrote:
>> Update of /cvsroot/naviserver/naviserver/nsd
>> In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv24426/nsd
>>
>> Modified Files:
>>        tclcache.c tclcmds.c
>> Log Message:
>> Added 2 new cache commands ns_cache_get and ns_cache_set for easier cache manipulation
>>
>>
>> Index: tclcmds.c
>> ===================================================================
>> RCS file: /cvsroot/naviserver/naviserver/nsd/tclcmds.c,v
>> retrieving revision 1.34
>> retrieving revision 1.35
>> diff -C2 -d -r1.34 -r1.35
>> *** tclcmds.c   28 Feb 2006 20:02:37 -0000      1.34
>> --- tclcmds.c   5 Apr 2006 17:52:31 -0000       1.35
>> ***************
>> *** 73,76 ****
>> --- 73,78 ----
>>      NsTclCacheCreateObjCmd,
>>      NsTclCacheEvalObjCmd,
>> +     NsTclCacheGetObjCmd,
>> +     NsTclCacheSetObjCmd,
>>      NsTclCacheFlushObjCmd,
>>      NsTclCacheIncrObjCmd,
>> ***************
>> *** 259,262 ****
>> --- 261,266 ----
>>      {"ns_cache_create", NULL, NsTclCacheCreateObjCmd},
>>      {"ns_cache_eval", NULL, NsTclCacheEvalObjCmd},
>> +     {"ns_cache_get", NULL, NsTclCacheGetObjCmd},
>> +     {"ns_cache_set", NULL, NsTclCacheSetObjCmd},
>>      {"ns_cache_flush", NULL, NsTclCacheFlushObjCmd},
>>      {"ns_cache_incr", NULL, NsTclCacheIncrObjCmd},
>>
>> Index: tclcache.c
>> ===================================================================
>> RCS file: /cvsroot/naviserver/naviserver/nsd/tclcache.c,v
>> retrieving revision 1.2
>> retrieving revision 1.3
>> diff -C2 -d -r1.2 -r1.3
>> *** tclcache.c  23 Jan 2006 15:57:33 -0000      1.2
>> --- tclcache.c  5 Apr 2006 17:52:31 -0000       1.3
>> ***************
>> *** 285,288 ****
>> --- 285,378 ----
>>  }
>>
>> + /*
>> +  *----------------------------------------------------------------------
>> +  *
>> +  * NsTclCacheGetObjCmd --
>> +  *
>> +  *      Returns entry value if entry exists in the cache and not expired yet
>> +  *
>> +  * Results:
>> +  *      TCL result with entry value or empty result
>> +  *
>> +  * Side effects:
>> +  *      None.
>> +  *
>> +  *----------------------------------------------------------------------
>> +  */
>> +
>> + int
>> + NsTclCacheGetObjCmd(ClientData arg, Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[])
>> + {
>> +     Ns_Cache *cache;
>> +     Ns_Entry *entry;
>> +     char     *key;
>> +
>> +     Ns_ObjvSpec args[] = {
>> +         {"cache",    ObjvCache,     &cache, arg},
>> +         {"key",      Ns_ObjvString, &key,   NULL},
>> +         {NULL, NULL, NULL, NULL}
>> +     };
>> +     if (Ns_ParseObjv(NULL, args, interp, 1, objc, objv) != NS_OK) {
>> +         return TCL_ERROR;
>> +     }
>> +     Ns_CacheLock(cache);
>> +     if ((entry = Ns_CacheFindEntry(cache, key)) != NULL) {
>> +         Tcl_SetStringObj(Tcl_GetObjResult(interp),
>> +                          Ns_CacheGetValue(entry), Ns_CacheGetSize(entry));
>> +     }
>> +     Ns_CacheUnlock(cache);
>> +     return TCL_OK;
>> + }
>> +
>> + /*
>> +  *----------------------------------------------------------------------
>> +  *
>> +  * NsTclCacheSetObjCmd --
>> +  *
>> +  *      Set new value of the cache entry
>> +  *
>> +  * Results:
>> +  *      TCL result.
>> +  *
>> +  * Side effects:
>> +  *      None.
>> +  *
>> +  *----------------------------------------------------------------------
>> +  */
>> +
>> + int
>> + NsTclCacheSetObjCmd(ClientData arg, Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[])
>> + {
>> +     NsInterp *itPtr = arg;
>> +     Ns_Cache *cache;
>> +     Ns_Entry *entry;
>> +     char     *key, *value = 0;
>> +     int       new, timeout = -1, ttl = 0;
>> +
>> +     Ns_ObjvSpec opts[] = {
>> +         {"-timeout", Ns_ObjvInt,   &timeout, NULL},
>> +         {"-ttl",     Ns_ObjvInt,   &ttl,     NULL},
>> +         {"--",       Ns_ObjvBreak, NULL,     NULL},
>> +         {NULL, NULL, NULL, NULL}
>> +     };
>> +     Ns_ObjvSpec args[] = {
>> +         {"cache",    ObjvCache,     &cache, arg},
>> +         {"key",      Ns_ObjvString, &key,   NULL},
>> +         {"value",    Ns_ObjvString, &value, NULL},
>> +         {NULL, NULL, NULL, NULL}
>> +     };
>> +     if (Ns_ParseObjv(opts, args, interp, 1, objc, objv) != NS_OK) {
>> +         return TCL_ERROR;
>> +     }
>> +     if ((entry = CreateEntry(itPtr, cache, key, &new, timeout)) == NULL) {
>> +         return TCL_ERROR;
>> +     }
>> +     Tcl_SetStringObj(Tcl_GetObjResult(interp), value, -1);
>> +     SetEntry(interp, entry, NULL, ttl);
>> +     Ns_CacheUnlock(cache);
>> +
>> +     return TCL_OK;
>> + }
>> +
>>
>>  /*
>>
>>
>>
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> 
> 
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-- 
Vlad Seryakov
571 262-8608 office
vl...@cr...
http://www.crystalballinc.com/vlad/