Ticket #342 - better error message when cache overflows

Bug description: ACL cache overflow error message is not very clear
and repeated too many times.

Fix description:
1) print a message like this:
   Your ACL cache of %d slots has overflowed.  This can happen
   when you have many ACIs.  This ACI evaluation requires %d
   slots to cache. You can increase your max value by setting
   the attribute nsslapd-aclpb-max-selected-acls in cn=ACL
   Plugin,cn=plugins,cn=config to a value higher. A server
   restart is required.
2) print the error message only once per ACI evaluation instead
   of hundreds of times

https://fedorahosted.org/389/ticket/342

Reviewed by Mark (Thanks!!)

ldap/servers/plugins/acl/acl.c

@@ -3108,17 +3108,33 @@ acl__TestRights(Acl_PBlock *aclpb,int access, char **right, char ** map_generic,
 				}
 			}
 
-			if ( j < aclpb->aclpb_last_cache_result)  {
+			if (j < aclpb->aclpb_last_cache_result)  {
 				/* already in cache */
-			} else if ( j < aclpb_max_cache_results ) {
-				/* j == aclpb->aclpb_last_cache_result  &&
-					j < ACLPB_MAX_CACHE_RESULTS */
+				aclpb->aclpb_cache_result[j].result &= 
+				        ~ACLPB_CACHE_ERROR_REPORTED;
+			} else if (j < aclpb_max_cache_results) {
+				/* j == aclpb->aclpb_last_cache_result &&
+				   j < ACLPB_MAX_CACHE_RESULTS */
 				aclpb->aclpb_last_cache_result++;
 				aclpb->aclpb_cache_result[j].aci_index = index;
 				aclpb->aclpb_cache_result[j].aci_ruleType = aci->aci_ruleType;
+				aclpb->aclpb_cache_result[j].result &= 
+				        ~ACLPB_CACHE_ERROR_REPORTED;
 			} else {  /* cache overflow */
-				slapi_log_error (SLAPI_LOG_FATAL, "acl__TestRights", "cache overflown\n");
-				if (  rights_rv == ACL_RES_ALLOW) {
+				if (!(aclpb->aclpb_cache_result[j].result &
+				      ACLPB_CACHE_ERROR_REPORTED)) {
+					slapi_log_error (SLAPI_LOG_FATAL, "acl__TestRights",
+					    "Your ACL cache of %d slots has overflowed. "
+					    "This can happen when you have many ACIs. "
+					    "This ACI evaluation requires %d slots to cache. "
+					    "You can increase your max value by setting the attribute "
+					    "%s in cn=ACL Plugin,cn=plugins,cn=config to a value higher. "
+					    "A server restart is required.\n",
+					    j, aclpb_max_cache_results, ATTR_ACLPB_MAX_SELECTED_ACLS);
+					aclpb->aclpb_cache_result[j].result |=
+					            ACLPB_CACHE_ERROR_REPORTED;
+				}
+				if (rights_rv == ACL_RES_ALLOW) {
 					result_reason->deciding_aci = aci;
 					result_reason->reason = ACL_REASON_EVALUATED_ALLOW;
 					TNF_PROBE_1_DEBUG(acl__TestRights_end,"ACL","",

ldap/servers/plugins/acl/acl.h

@@ -361,6 +361,7 @@ typedef struct result_cache {
 #define ACLPB_CACHE_SEARCH_RES_DENY		(short)0x0008 /* used for DENY handles only */
 #define ACLPB_CACHE_SEARCH_RES_SKIP		(short)0x0010 /* used for both types */
 #define ACLPB_CACHE_READ_RES_SKIP		(short)0x0020 /* used for both types */
+#define ACLPB_CACHE_ERROR_REPORTED		(short)0x8000 /* error is reported */
 }r_cache_t;