+extern RRDHOST *localhost;
+
+#define rrdhost_rdlock(host) netdata_rwlock_rdlock(&((host)->rrdhost_rwlock))
+#define rrdhost_wrlock(host) netdata_rwlock_wrlock(&((host)->rrdhost_rwlock))
+#define rrdhost_unlock(host) netdata_rwlock_unlock(&((host)->rrdhost_rwlock))
+
+// ----------------------------------------------------------------------------
+// these loop macros make sure the linked list is accessed with the right lock
+
+#define rrdhost_foreach_read(var) \
+ for(var = localhost, rrd_check_rdlock(); var ; var = var->next)
+
+#define rrdhost_foreach_write(var) \
+ for(var = localhost, rrd_check_wrlock(); var ; var = var->next)
+
+
+// ----------------------------------------------------------------------------
+// global lock for all RRDHOSTs
+
+extern netdata_rwlock_t rrd_rwlock;
+
+#define rrd_rdlock() netdata_rwlock_rdlock(&rrd_rwlock)
+#define rrd_wrlock() netdata_rwlock_wrlock(&rrd_rwlock)
+#define rrd_unlock() netdata_rwlock_unlock(&rrd_rwlock)
+
+// ----------------------------------------------------------------------------
+
+extern size_t rrd_hosts_available;
+extern time_t rrdhost_free_orphan_time;
+
+extern void rrd_init(char *hostname);
+
+extern RRDHOST *rrdhost_find_by_hostname(const char *hostname, uint32_t hash);
+extern RRDHOST *rrdhost_find_by_guid(const char *guid, uint32_t hash);
+
+extern RRDHOST *rrdhost_find_or_create(
+ const char *hostname
+ , const char *guid
+ , const char *os
+ , int update_every
+ , long history
+ , RRD_MEMORY_MODE mode
+ , int health_enabled
+ , int rrdpush_enabled
+ , char *rrdpush_destination
+ , char *rrdpush_api_key
+);
+
+#if defined(NETDATA_INTERNAL_CHECKS) && defined(NETDATA_VERIFY_LOCKS)
+extern void __rrdhost_check_wrlock(RRDHOST *host, const char *file, const char *function, const unsigned long line);
+extern void __rrdhost_check_rdlock(RRDHOST *host, const char *file, const char *function, const unsigned long line);
+extern void __rrdset_check_rdlock(RRDSET *st, const char *file, const char *function, const unsigned long line);
+extern void __rrdset_check_wrlock(RRDSET *st, const char *file, const char *function, const unsigned long line);
+extern void __rrd_check_rdlock(const char *file, const char *function, const unsigned long line);
+extern void __rrd_check_wrlock(const char *file, const char *function, const unsigned long line);
+
+#define rrdhost_check_rdlock(host) __rrdhost_check_rdlock(host, __FILE__, __FUNCTION__, __LINE__)
+#define rrdhost_check_wrlock(host) __rrdhost_check_wrlock(host, __FILE__, __FUNCTION__, __LINE__)
+#define rrdset_check_rdlock(st) __rrdset_check_rdlock(st, __FILE__, __FUNCTION__, __LINE__)
+#define rrdset_check_wrlock(st) __rrdset_check_wrlock(st, __FILE__, __FUNCTION__, __LINE__)
+#define rrd_check_rdlock() __rrd_check_rdlock(__FILE__, __FUNCTION__, __LINE__)
+#define rrd_check_wrlock() __rrd_check_wrlock(__FILE__, __FUNCTION__, __LINE__)