cachedb_perfd: new CacheDB backend for the perfcached daemon

perfd://[:secret@]host:port[,host:port...]/collection[?opts] reaches a
perfcached node or cluster through libperfd (0.7.5 or later, MIT):
Noise-authenticated binary protocol, member discovery from a seed,
per-key routing to the owning node, standby connections and failover.

- get/set/remove/add/sub/counter_fetch over the core Key-Value API
- cache_raw_query(): MGET, EXISTS, EXPIRE, JSON.SET/GET/DEL
- perfd_fetch(): asynchronous fetch from an async() statement
- lazy, pid-stamped per-process connections (fork safe); the Noise
  key is derived once in the parent and inherited by the workers

Excluded from the default build like the other modules that need an
external client library.

Author: Lt-Flash

Makefile.conf.template

@@ -7,6 +7,7 @@
 #cachedb_dynamodb= Implementation of a cache system designed to work with Dynamodb servers | libaws-cpp-sdk-core and libaws-cpp-sdk-dynamodb
 #cachedb_memcached= Implementation of a cache system designed to work with a memcached server. | Memcached client library, typically libmemcached
 #cachedb_mongodb= Implementation of a cache system designed to work with a MongoDB server. | libjson and the mongo-c-driver
+#cachedb_perfd= Implementation of a cache system designed to work with perfcached servers | perfcached client library, libperfd 0.7.5 or higher
 #cachedb_redis= Implementation of a cache system designed to work with Redis servers | Redis client library, hiredis
 #carrierroute= Provides routing, balancing and blacklisting capabilities. | libconfuse, a configuration file parser library
 #cgrates= Provides integration with the CGRateS billing/rating engine. | JSON library, libjson
@@ -76,7 +77,7 @@
 #uuid= UUID generator | uuid-dev
 
 # Modules omitted from the default build, generally due to external dependencies.
-exclude_modules?= aaa_diameter aaa_radius auth_jwt auth_web3 b2b_logic_xml cachedb_cassandra cachedb_couchbase cachedb_dynamodb cachedb_memcached cachedb_mongodb cachedb_redis carrierroute cgrates compression cpl_c db_berkeley db_http db_mysql db_oracle db_perlvdb db_postgres db_sqlite db_unixodbc dialplan emergency event_rabbitmq event_kafka event_sqs h350 httpd http2d identity jabber json launch_darkly ldap lua mi_xmlrpc mmgeoip opentelemetry osp perl pi_http presence presence_dialoginfo presence_mwi presence_reginfo presence_xml presence_dfks proto_ipsec proto_sctp proto_tls proto_wss pua pua_bla pua_dialoginfo pua_mi pua_reginfo pua_usrloc pua_xmpp python regex rabbitmq_consumer rest_client rls rtp.io siprec sngtc snmpstats stir_shaken tls_mgm tls_openssl tls_wolfssl uuid xcap xcap_client xml xmpp
+exclude_modules?= aaa_diameter aaa_radius auth_jwt auth_web3 b2b_logic_xml cachedb_cassandra cachedb_couchbase cachedb_dynamodb cachedb_memcached cachedb_mongodb cachedb_perfd cachedb_redis carrierroute cgrates compression cpl_c db_berkeley db_http db_mysql db_oracle db_perlvdb db_postgres db_sqlite db_unixodbc dialplan emergency event_rabbitmq event_kafka event_sqs h350 httpd http2d identity jabber json launch_darkly ldap lua mi_xmlrpc mmgeoip opentelemetry osp perl pi_http presence presence_dialoginfo presence_mwi presence_reginfo presence_xml presence_dfks proto_ipsec proto_sctp proto_tls proto_wss pua pua_bla pua_dialoginfo pua_mi pua_reginfo pua_usrloc pua_xmpp python regex rabbitmq_consumer rest_client rls rtp.io siprec sngtc snmpstats stir_shaken tls_mgm tls_openssl tls_wolfssl uuid xcap xcap_client xml xmpp
 
 # Modules forced into the build, even when also listed in exclude_modules.
 include_modules?=

modules/cachedb_perfd/Makefile

@@ -0,0 +1,26 @@
+#
+# cachedb_perfd - perfcached client through libperfd
+#
+# WARNING: do not run this directly, it should be run by the master Makefile
+#
+# libperfd (0.7.5 or later) is linked, never compiled in: install
+# libperfd-dev, or run `make install-lib` in perfcached; pkg-config finds it.
+# PERFD_STATIC=1 links libperfd.a instead of libperfd.so; PKG_CONFIG_PATH
+# points at a libperfd in another prefix.
+include ../../Makefile.defs
+auto_gen=
+NAME=cachedb_perfd.so
+
+ifeq ($(filter clean proper realclean distclean,$(MAKECMDGOALS)),)
+ifeq ($(shell pkg-config --atleast-version=0.7.5 libperfd && echo yes),)
+$(error cachedb_perfd needs libperfd 0.7.5 or later - install libperfd-dev, or `make install-lib` in perfcached and set PKG_CONFIG_PATH)
+endif
+endif
+DEFS+=$(shell pkg-config --cflags libperfd 2>/dev/null)
+ifeq ($(PERFD_STATIC),1)
+LIBS+=$(shell pkg-config --variable=libdir libperfd 2>/dev/null)/libperfd.a -lsodium -lpthread
+else
+LIBS+=$(shell pkg-config --libs libperfd 2>/dev/null)
+endif
+
+include ../../Makefile.modules