Remove extern from function declared in headers. (#13790)

By default functions are declared as extern in C/C++ headers. The goal
of this PR is to reduce the wall of text that many headers have and,
more importantly, to make the declaration of extern'd variables - of
which we have many dispersed in various places - easily and quickly
identifiable.

Automatically generated with:

    $ git grep -l '^extern.*(' '**.h' | \
            grep -v libjudy | \
            grep -v 'sqlite3.h' | \
            xargs sed -i -e 's/extern \(.*(.*$\)/\1/'

This is a NFC.

25 files changed, 164 insertions, 164 deletions

diff --git a/collectors/ebpf.plugin/ebpf.h b/collectors/ebpf.plugin/ebpf.h
index 899d3b7b7e..beb724faed 100644
--- a/collectors/ebpf.plugin/ebpf.h
+++ b/collectors/ebpf.plugin/ebpf.h
@@ -163,8 +163,8 @@ enum ebpf_algorithms_list {
 };
 
 // Threads
-extern void *ebpf_process_thread(void *ptr);
-extern void *ebpf_socket_thread(void *ptr);
+void *ebpf_process_thread(void *ptr);
+void *ebpf_socket_thread(void *ptr);
 
 // Common variables
 extern pthread_mutex_t lock;
@@ -177,14 +177,14 @@ extern pthread_mutex_t collect_data_mutex;
 extern pthread_cond_t collect_data_cond_var;
 
 // Common functions
-extern void ebpf_global_labels(netdata_syscall_stat_t *is,
+void ebpf_global_labels(netdata_syscall_stat_t *is,
                                netdata_publish_syscall_t *pio,
                                char **dim,
                                char **name,
                                int *algorithm,
                                int end);
 
-extern void ebpf_write_chart_cmd(char *type,
+void ebpf_write_chart_cmd(char *type,
                                  char *id,
                                  char *title,
                                  char *units,
@@ -195,11 +195,11 @@ extern void ebpf_write_chart_cmd(char *type,
                                  int update_every,
                                  char *module);
 
-extern void ebpf_write_global_dimension(char *name, char *id, char *algorithm);
+void ebpf_write_global_dimension(char *name, char *id, char *algorithm);
 
-extern void ebpf_create_global_dimension(void *ptr, int end);
+void ebpf_create_global_dimension(void *ptr, int end);
 
-extern void ebpf_create_chart(char *type,
+void ebpf_create_chart(char *type,
                               char *id,
                               char *title,
                               char *units,
@@ -213,18 +213,18 @@ extern void ebpf_create_chart(char *type,
                               int update_every,
                               char *module);
 
-extern void write_begin_chart(char *family, char *name);
+void write_begin_chart(char *family, char *name);
 
-extern void write_chart_dimension(char *dim, long long value);
+void write_chart_dimension(char *dim, long long value);
 
-extern void write_count_chart(char *name, char *family, netdata_publish_syscall_t *move, uint32_t end);
+void write_count_chart(char *name, char *family, netdata_publish_syscall_t *move, uint32_t end);
 
-extern void write_err_chart(char *name, char *family, netdata_publish_syscall_t *move, int end);
+void write_err_chart(char *name, char *family, netdata_publish_syscall_t *move, int end);
 
-extern void write_io_chart(char *chart, char *family, char *dwrite, long long vwrite,
+void write_io_chart(char *chart, char *family, char *dwrite, long long vwrite,
                            char *dread, long long vread);
 
-extern void ebpf_create_charts_on_apps(char *name,
+void ebpf_create_charts_on_apps(char *name,
                                        char *title,
                                        char *units,
                                        char *family,
@@ -235,15 +235,15 @@ extern void ebpf_create_charts_on_apps(char *name,
                                        int update_every,
                                        char *module);
 
-extern void write_end_chart();
+void write_end_chart();
 
-extern void ebpf_cleanup_publish_syscall(netdata_publish_syscall_t *nps);
+void ebpf_cleanup_publish_syscall(netdata_publish_syscall_t *nps);
 
-extern int ebpf_enable_tracepoint(ebpf_tracepoint_t *tp);
-extern int ebpf_disable_tracepoint(ebpf_tracepoint_t *tp);
-extern uint32_t ebpf_enable_tracepoints(ebpf_tracepoint_t *tps);
+int ebpf_enable_tracepoint(ebpf_tracepoint_t *tp);
+int ebpf_disable_tracepoint(ebpf_tracepoint_t *tp);
+uint32_t ebpf_enable_tracepoints(ebpf_tracepoint_t *tps);
 
-extern void ebpf_pid_file(char *filename, size_t length);
+void ebpf_pid_file(char *filename, size_t length);
 
 #define EBPF_PROGRAMS_SECTION "ebpf programs"
 
@@ -279,15 +279,15 @@ extern void *default_btf;
 
 // Socket functions and variables
 // Common functions
-extern void ebpf_process_create_apps_charts(struct ebpf_module *em, void *ptr);
-extern void ebpf_socket_create_apps_charts(struct ebpf_module *em, void *ptr);
-extern void ebpf_cachestat_create_apps_charts(struct ebpf_module *em, void *root);
-extern void ebpf_one_dimension_write_charts(char *family, char *chart, char *dim, long long v1);
-extern collected_number get_value_from_structure(char *basis, size_t offset);
-extern void ebpf_update_pid_table(ebpf_local_maps_t *pid, ebpf_module_t *em);
-extern void ebpf_write_chart_obsolete(char *type, char *id, char *title, char *units, char *family,
+void ebpf_process_create_apps_charts(struct ebpf_module *em, void *ptr);
+void ebpf_socket_create_apps_charts(struct ebpf_module *em, void *ptr);
+void ebpf_cachestat_create_apps_charts(struct ebpf_module *em, void *root);
+void ebpf_one_dimension_write_charts(char *family, char *chart, char *dim, long long v1);
+collected_number get_value_from_structure(char *basis, size_t offset);
+void ebpf_update_pid_table(ebpf_local_maps_t *pid, ebpf_module_t *em);
+void ebpf_write_chart_obsolete(char *type, char *id, char *title, char *units, char *family,
                                       char *charttype, char *context, int order, int update_every);
-extern void write_histogram_chart(char *family, char *name, const netdata_idx_t *hist, char **dimensions, uint32_t end);
+void write_histogram_chart(char *family, char *name, const netdata_idx_t *hist, char **dimensions, uint32_t end);
 void ebpf_update_disabled_plugin_stats(ebpf_module_t *em);
 extern ebpf_filesystem_partitions_t localfs[];
 extern ebpf_sync_syscalls_t local_syscalls[];
diff --git a/collectors/ebpf.plugin/ebpf_apps.h b/collectors/ebpf.plugin/ebpf_apps.h
index f65a137b54..0bea9122f5 100644
--- a/collectors/ebpf.plugin/ebpf_apps.h
+++ b/collectors/ebpf.plugin/ebpf_apps.h
@@ -408,30 +408,30 @@ static inline void debug_log_int(const char *fmt, ...)
 //
 extern struct pid_stat **all_pids;
 
-extern int ebpf_read_apps_groups_conf(struct target **apps_groups_default_target,
+int ebpf_read_apps_groups_conf(struct target **apps_groups_default_target,
                                       struct target **apps_groups_root_target,
                                       const char *path,
                                       const char *file);
 
-extern void clean_apps_groups_target(struct target *apps_groups_root_target);
+void clean_apps_groups_target(struct target *apps_groups_root_target);
 
-extern size_t zero_all_targets(struct target *root);
+size_t zero_all_targets(struct target *root);
 
-extern int am_i_running_as_root();
+int am_i_running_as_root();
 
-extern void cleanup_exited_pids();
+void cleanup_exited_pids();
 
-extern int ebpf_read_hash_table(void *ep, int fd, uint32_t pid);
+int ebpf_read_hash_table(void *ep, int fd, uint32_t pid);
 
-extern int get_pid_comm(pid_t pid, size_t n, char *dest);
+int get_pid_comm(pid_t pid, size_t n, char *dest);
 
-extern size_t read_processes_statistic_using_pid_on_target(ebpf_process_stat_t **ep,
+size_t read_processes_statistic_using_pid_on_target(ebpf_process_stat_t **ep,
                                                            int fd,
                                                            struct pid_on_target *pids);
 
-extern size_t read_bandwidth_statistic_using_pid_on_target(ebpf_bandwidth_t **ep, int fd, struct pid_on_target *pids);
+size_t read_bandwidth_statistic_using_pid_on_target(ebpf_bandwidth_t **ep, int fd, struct pid_on_target *pids);
 
-extern void collect_data_for_all_processes(int tbl_pid_stats_fd);
+void collect_data_for_all_processes(int tbl_pid_stats_fd);
 
 extern ebpf_process_stat_t **global_process_stats;
 extern ebpf_process_publish_apps_t **current_apps_data;
diff --git a/collectors/ebpf.plugin/ebpf_cachestat.h b/collectors/ebpf.plugin/ebpf_cachestat.h
index 4733260487..07f0745d42 100644
--- a/collectors/ebpf.plugin/ebpf_cachestat.h
+++ b/collectors/ebpf.plugin/ebpf_cachestat.h
@@ -81,7 +81,7 @@ typedef struct netdata_publish_cachestat {
     netdata_cachestat_pid_t prev;
 } netdata_publish_cachestat_t;
 
-extern void *ebpf_cachestat_thread(void *ptr);
+void *ebpf_cachestat_thread(void *ptr);
 
 extern struct config cachestat_config;
 extern netdata_ebpf_targets_t cachestat_targets[];
diff --git a/collectors/ebpf.plugin/ebpf_cgroup.h b/collectors/ebpf.plugin/ebpf_cgroup.h
index cca9a950d1..5956adee7f 100644
--- a/collectors/ebpf.plugin/ebpf_cgroup.h
+++ b/collectors/ebpf.plugin/ebpf_cgroup.h
@@ -60,10 +60,10 @@ typedef struct ebpf_cgroup_target {
     struct ebpf_cgroup_target *next;
 } ebpf_cgroup_target_t;
 
-extern void ebpf_map_cgroup_shared_memory();
-extern void ebpf_parse_cgroup_shm_data();
-extern void ebpf_close_cgroup_shm();
-extern void ebpf_create_charts_on_systemd(char *id, char *title, char *units, char *family, char *charttype, int order,
+void ebpf_map_cgroup_shared_memory();
+void ebpf_parse_cgroup_shm_data();
+void ebpf_close_cgroup_shm();
+void ebpf_create_charts_on_systemd(char *id, char *title, char *units, char *family, char *charttype, int order,
                                           char *algorithm, char *context, char *module, int update_every);
 
 #endif /* NETDATA_EBPF_CGROUP_H */
diff --git a/collectors/ebpf.plugin/ebpf_dcstat.h b/collectors/ebpf.plugin/ebpf_dcstat.h
index a5872a1b76..d8687f9681 100644
--- a/collectors/ebpf.plugin/ebpf_dcstat.h
+++ b/collectors/ebpf.plugin/ebpf_dcstat.h
@@ -75,8 +75,8 @@ typedef struct netdata_publish_dcstat {
     netdata_dcstat_pid_t prev;
 } netdata_publish_dcstat_t;
 
-extern void *ebpf_dcstat_thread(void *ptr);
-extern void ebpf_dcstat_create_apps_charts(struct ebpf_module *em, void *ptr);
+void *ebpf_dcstat_thread(void *ptr);
+void ebpf_dcstat_create_apps_charts(struct ebpf_module *em, void *ptr);
 extern struct config dcstat_config;
 extern netdata_ebpf_targets_t dc_targets[];
 extern ebpf_local_maps_t dcstat_maps[];
diff --git a/collectors/ebpf.plugin/ebpf_disk.h b/collectors/ebpf.plugin/ebpf_disk.h
index 8e58174b9a..c14b887f8c 100644
--- a/collectors/ebpf.plugin/ebpf_disk.h
+++ b/collectors/ebpf.plugin/ebpf_disk.h
@@ -72,7 +72,7 @@ typedef struct netdata_ebpf_publish_disk {
 
 extern struct config disk_config;
 
-extern void *ebpf_disk_thread(void *ptr);
+void *ebpf_disk_thread(void *ptr);
 
 #endif /* NETDATA_EBPF_DISK_H */
 
diff --git a/collectors/ebpf.plugin/ebpf_fd.h b/collectors/ebpf.plugin/ebpf_fd.h
index 481cee14c0..914a34b989 100644
--- a/collectors/ebpf.plugin/ebpf_fd.h
+++ b/collectors/ebpf.plugin/ebpf_fd.h
@@ -75,8 +75,8 @@ enum fd_syscalls {
 };
 
 
-extern void *ebpf_fd_thread(void *ptr);
-extern void ebpf_fd_create_apps_charts(struct ebpf_module *em, void *ptr);
+void *ebpf_fd_thread(void *ptr);
+void ebpf_fd_create_apps_charts(struct ebpf_module *em, void *ptr);
 extern struct config fd_config;
 extern netdata_fd_stat_t **fd_pid;
 extern netdata_ebpf_targets_t fd_targets[];
diff --git a/collectors/ebpf.plugin/ebpf_filesystem.h b/collectors/ebpf.plugin/ebpf_filesystem.h
index f6a10c8748..0d558df7d3 100644
--- a/collectors/ebpf.plugin/ebpf_filesystem.h
+++ b/collectors/ebpf.plugin/ebpf_filesystem.h
@@ -43,7 +43,7 @@ enum netdata_filesystem_table {
     NETDATA_ADDR_FS_TABLE
 };
 
-extern void *ebpf_filesystem_thread(void *ptr);
+void *ebpf_filesystem_thread(void *ptr);
 extern struct config fs_config;
 
 #endif /* NETDATA_EBPF_FILESYSTEM_H */
diff --git a/collectors/ebpf.plugin/ebpf_hardirq.h b/collectors/ebpf.plugin/ebpf_hardirq.h
index 4c8a7a0988..381da57d8e 100644
--- a/collectors/ebpf.plugin/ebpf_hardirq.h
+++ b/collectors/ebpf.plugin/ebpf_hardirq.h
@@ -68,6 +68,6 @@ typedef struct hardirq_static_val {
 } hardirq_static_val_t;
 
 extern struct config hardirq_config;
-extern void *ebpf_hardirq_thread(void *ptr);
+void *ebpf_hardirq_thread(void *ptr);
 
 #endif /* NETDATA_EBPF_HARDIRQ_H */
diff --git a/collectors/ebpf.plugin/ebpf_mdflush.h b/collectors/ebpf.plugin/ebpf_mdflush.h
index 59856ad676..b04eefd28d 100644
--- a/collectors/ebpf.plugin/ebpf_mdflush.h
+++ b/collectors/ebpf.plugin/ebpf_mdflush.h
@@ -35,7 +35,7 @@ typedef struct netdata_mdflush {
     uint64_t cnt;
 } netdata_mdflush_t;
 
-extern void *ebpf_mdflush_thread(void *ptr);
+void *ebpf_mdflush_thread(void *ptr);
 
 extern struct config mdflush_config;
 
diff --git a/collectors/ebpf.plugin/ebpf_mount.h b/collectors/ebpf.plugin/ebpf_mount.h
index d4f48efd10..5a8d11a59c 100644
--- a/collectors/ebpf.plugin/ebpf_mount.h
+++ b/collectors/ebpf.plugin/ebpf_mount.h
@@ -38,7 +38,7 @@ enum netdata_mount_syscalls {
 };
 
 extern struct config mount_config;
-extern void *ebpf_mount_thread(void *ptr);
+void *ebpf_mount_thread(void *ptr);
 extern netdata_ebpf_targets_t mount_targets[];
 
 #endif /* NETDATA_EBPF_MOUNT_H */
diff --git a/collectors/ebpf.plugin/ebpf_oomkill.h b/collectors/ebpf.plugin/ebpf_oomkill.h
index b5f04c74c9..7860863841 100644
--- a/collectors/ebpf.plugin/ebpf_oomkill.h
+++ b/collectors/ebpf.plugin/ebpf_oomkill.h
@@ -26,7 +26,7 @@ typedef uint8_t oomkill_ebpf_val_t;
 #define NETDATA_CGROUP_OOMKILLS_CONTEXT "cgroup.oomkills"
 
 extern struct config oomkill_config;
-extern void *ebpf_oomkill_thread(void *ptr);
-extern void ebpf_oomkill_create_apps_charts(struct ebpf_module *em, void *ptr);
+void *ebpf_oomkill_thread(void *ptr);
+void ebpf_oomkill_create_apps_charts(struct ebpf_module *em, void *ptr);
 
 #endif /* NETDATA_EBPF_OOMKILL_H */
diff --git a/collectors/ebpf.plugin/ebpf_shm.h b/collectors/ebpf.plugin/ebpf_shm.h
index 8e118a6f58..4e068819bd 100644
--- a/collectors/ebpf.plugin/ebpf_shm.h
+++ b/collectors/ebpf.plugin/ebpf_shm.h
@@ -54,8 +54,8 @@ enum shm_counters {
 
 extern netdata_publish_shm_t **shm_pid;
 
-extern void *ebpf_shm_thread(void *ptr);
-extern void ebpf_shm_create_apps_charts(struct ebpf_module *em, void *ptr);
+void *ebpf_shm_thread(void *ptr);
+void ebpf_shm_create_apps_charts(struct ebpf_module *em, void *ptr);
 extern netdata_ebpf_targets_t shm_targets[];
 
 extern struct config shm_config;
diff --git a/collectors/ebpf.plugin/ebpf_socket.h b/collectors/ebpf.plugin/ebpf_socket.h
index 711225acf1..ca6b193f0f 100644
--- a/collectors/ebpf.plugin/ebpf_socket.h
+++ b/collectors/ebpf.plugin/ebpf_socket.h
@@ -356,12 +356,12 @@ typedef struct netdata_vector_plot {
 
 } netdata_vector_plot_t;
 
-extern void clean_port_structure(ebpf_network_viewer_port_list_t **clean);
+void clean_port_structure(ebpf_network_viewer_port_list_t **clean);
 extern ebpf_network_viewer_port_list_t *listen_ports;
-extern void update_listen_table(uint16_t value, uint16_t proto, netdata_passive_connection_t *values);
-extern void parse_network_viewer_section(struct config *cfg);
-extern void fill_ip_list(ebpf_network_viewer_ip_list_t **out, ebpf_network_viewer_ip_list_t *in, char *table);
-extern void parse_service_name_section(struct config *cfg);
+void update_listen_table(uint16_t value, uint16_t proto, netdata_passive_connection_t *values);
+void parse_network_viewer_section(struct config *cfg);
+void fill_ip_list(ebpf_network_viewer_ip_list_t **out, ebpf_network_viewer_ip_list_t *in, char *table);
+void parse_service_name_section(struct config *cfg);
 
 extern ebpf_socket_publish_apps_t **socket_bandwidth_curr;
 extern struct config socket_config;
diff --git a/collectors/ebpf.plugin/ebpf_softirq.h b/collectors/ebpf.plugin/ebpf_softirq.h
index a227518952..7dcddbb493 100644
--- a/collectors/ebpf.plugin/ebpf_softirq.h
+++ b/collectors/ebpf.plugin/ebpf_softirq.h
@@ -29,6 +29,6 @@ typedef struct sofirq_val {
 } softirq_val_t;
 
 extern struct config softirq_config;
-extern void *ebpf_softirq_thread(void *ptr);
+void *ebpf_softirq_thread(void *ptr);
 
 #endif /* NETDATA_EBPF_SOFTIRQ_H */
diff --git a/collectors/ebpf.plugin/ebpf_swap.h b/collectors/ebpf.plugin/ebpf_swap.h
index 80c2c8e946..79182e52e8 100644
--- a/collectors/ebpf.plugin/ebpf_swap.h
+++ b/collectors/ebpf.plugin/ebpf_swap.h
@@ -44,8 +44,8 @@ enum swap_counters {
 
 extern netdata_publish_swap_t **swap_pid;
 
-extern void *ebpf_swap_thread(void *ptr);
-extern void ebpf_swap_create_apps_charts(struct ebpf_module *em, void *ptr);
+void *ebpf_swap_thread(void *ptr);
+void ebpf_swap_create_apps_charts(struct ebpf_module *em, void *ptr);
 
 extern struct config swap_config;
 extern netdata_ebpf_targets_t swap_targets[];
diff --git a/collectors/ebpf.plugin/ebpf_sync.h b/collectors/ebpf.plugin/ebpf_sync.h
index a52434c171..cace2a1cf6 100644
--- a/collectors/ebpf.plugin/ebpf_sync.h
+++ b/collectors/ebpf.plugin/ebpf_sync.h
@@ -52,7 +52,7 @@ enum netdata_sync_table {
     NETDATA_SYNC_GLOBAL_TABLE
 };
 
-extern void *ebpf_sync_thread(void *ptr);
+void *ebpf_sync_thread(void *ptr);
 extern struct config sync_config;
 extern netdata_ebpf_targets_t sync_targets[];
 
diff --git a/collectors/ebpf.plugin/ebpf_vfs.h b/collectors/ebpf.plugin/ebpf_vfs.h
index 7d23e2994e..2e3c7cc295 100644
--- a/collectors/ebpf.plugin/ebpf_vfs.h
+++ b/collectors/ebpf.plugin/ebpf_vfs.h
@@ -168,8 +168,8 @@ enum netdata_vfs_calls_name {
 
 extern netdata_publish_vfs_t **vfs_pid;
 
-extern void *ebpf_vfs_thread(void *ptr);
-extern void ebpf_vfs_create_apps_charts(struct ebpf_module *em, void *ptr);
+void *ebpf_vfs_thread(void *ptr);
+void ebpf_vfs_create_apps_charts(struct ebpf_module *em, void *ptr);
 extern netdata_ebpf_targets_t vfs_targets[];
 
 extern struct config vfs_config;
diff --git a/collectors/freebsd.plugin/plugin_freebsd.h b/collectors/freebsd.plugin/plugin_freebsd.h
index 3a4ec13a7b..af7d0822e0 100644
--- a/collectors/freebsd.plugin/plugin_freebsd.h
+++ b/collectors/freebsd.plugin/plugin_freebsd.h
@@ -13,41 +13,41 @@
 
 #define MAX_INT_DIGITS 10 // maximum number of digits for int
 
-extern int freebsd_plugin_init();
-
-extern int do_vm_loadavg(int update_every, usec_t dt);
-extern int do_vm_vmtotal(int update_every, usec_t dt);
-extern int do_kern_cp_time(int update_every, usec_t dt);
-extern int do_kern_cp_times(int update_every, usec_t dt);
-extern int do_dev_cpu_temperature(int update_every, usec_t dt);
-extern int do_dev_cpu_0_freq(int update_every, usec_t dt);
-extern int do_hw_intcnt(int update_every, usec_t dt);
-extern int do_vm_stats_sys_v_intr(int update_every, usec_t dt);
-extern int do_vm_stats_sys_v_soft(int update_every, usec_t dt);
-extern int do_vm_stats_sys_v_swtch(int update_every, usec_t dt);
-extern int do_vm_stats_sys_v_forks(int update_every, usec_t dt);
-extern int do_vm_swap_info(int update_every, usec_t dt);
-extern int do_system_ram(int update_every, usec_t dt);
-extern int do_vm_stats_sys_v_swappgs(int update_every, usec_t dt);
-extern int do_vm_stats_sys_v_pgfaults(int update_every, usec_t dt);
-extern int do_kern_ipc_sem(int update_every, usec_t dt);
-extern int do_kern_ipc_shm(int update_every, usec_t dt);
-extern int do_kern_ipc_msq(int update_every, usec_t dt);
-extern int do_uptime(int update_every, usec_t dt);
-extern int do_net_isr(int update_every, usec_t dt);
-extern int do_net_inet_tcp_states(int update_every, usec_t dt);
-extern int do_net_inet_tcp_stats(int update_every, usec_t dt);
-extern int do_net_inet_udp_stats(int update_every, usec_t dt);
-extern int do_net_inet_icmp_stats(int update_every, usec_t dt);
-extern int do_net_inet_ip_stats(int update_every, usec_t dt);
-extern int do_net_inet6_ip6_stats(int update_every, usec_t dt);
-extern int do_net_inet6_icmp6_stats(int update_every, usec_t dt);
-extern int do_getifaddrs(int update_every, usec_t dt);
-extern int do_getmntinfo(int update_every, usec_t dt);
-extern int do_kern_devstat(int update_every, usec_t dt);
-extern int do_kstat_zfs_misc_arcstats(int update_every, usec_t dt);
-extern int do_kstat_zfs_misc_zio_trim(int update_every, usec_t dt);
-extern int do_ipfw(int update_every, usec_t dt);
+int freebsd_plugin_init();
+
+int do_vm_loadavg(int update_every, usec_t dt);
+int do_vm_vmtotal(int update_every, usec_t dt);
+int do_kern_cp_time(int update_every, usec_t dt);
+int do_kern_cp_times(int update_every, usec_t dt);
+int do_dev_cpu_temperature(int update_every, usec_t dt);
+int do_dev_cpu_0_freq(int update_every, usec_t dt);
+int do_hw_intcnt(int update_every, usec_t dt);
+int do_vm_stats_sys_v_intr(int update_every, usec_t dt);
+int do_vm_stats_sys_v_soft(int update_every, usec_t dt);
+int do_vm_stats_sys_v_swtch(int update_every, usec_t dt);
+int do_vm_stats_sys_v_forks(int update_every, usec_t dt);
+int do_vm_swap_info(int update_every, usec_t dt);
+int do_system_ram(int update_every, usec_t dt);
+int do_vm_stats_sys_v_swappgs(int update_every, usec_t dt);
+int do_vm_stats_sys_v_pgfaults(int update_every, usec_t dt);
+int do_kern_ipc_sem(int update_every, usec_t dt);
+int do_kern_ipc_shm(int update_every, usec_t dt);
+int do_kern_ipc_msq(int update_every, usec_t dt);
+int do_uptime(int update_every, usec_t dt);
+int do_net_isr(int update_every, usec_t dt);
+int do_net_inet_tcp_states(int update_every, usec_t dt);
+int do_net_inet_tcp_stats(int update_every, usec_t dt);
+int do_net_inet_udp_stats(int update_every, usec_t dt);
+int do_net_inet_icmp_stats(int update_every, usec_t dt);
+int do_net_inet_ip_stats(int update_every, usec_t dt);
+int do_net_inet6_ip6_stats(int update_every, usec_t dt);
+int do_net_inet6_icmp6_stats(int update_every, usec_t dt);
+int do_getifaddrs(int update_every, usec_t dt);
+int do_getmntinfo(int update_every, usec_t dt);
+int do_kern_devstat(int update_every, usec_t dt);
+int do_kstat_zfs_misc_arcstats(int update_every, usec_t dt);
+int do_kstat_zfs_misc_zio_trim(int update_every, usec_t dt);
+int do_ipfw(int update_every, usec_t dt);
 
 // metrics that need to be shared among data collectors
 extern unsigned long long zfs_arcstats_shrinkable_cache_size_bytes;
diff --git a/collectors/macos.plugin/plugin_macos.h b/collectors/macos.plugin/plugin_macos.h
index b4c2cf542d..2c673a2243 100644
--- a/collectors/macos.plugin/plugin_macos.h
+++ b/collectors/macos.plugin/plugin_macos.h
@@ -5,8 +5,8 @@
 
 #include "daemon/common.h"
 
-extern int do_macos_sysctl(int update_every, usec_t dt);
-extern int do_macos_mach_smi(int update_every, usec_t dt);
-extern int do_macos_iokit(int update_every, usec_t dt);
+int do_macos_sysctl(int update_every, usec_t dt);
+int do_macos_mach_smi(int update_every, usec_t dt);
+int do_macos_iokit(int update_every, usec_t dt);
 
 #endif /* NETDATA_PLUGIN_MACOS_H */
diff --git a/collectors/plugins.d/plugins_d.h b/collectors/plugins.d/plugins_d.h
index 1749ad7090..5a7cccb5b6 100644
--- a/collectors/plugins.d/plugins_d.h
+++ b/collectors/plugins.d/plugins_d.h
@@ -67,9 +67,9 @@ struct plugind {
 
 extern struct plugind *pluginsd_root;
 
-extern size_t pluginsd_process(RRDHOST *host, struct plugind *cd, FILE *fp_plugin_input, FILE *fp_plugin_output, int trust_durations);
+size_t pluginsd_process(RRDHOST *host, struct plugind *cd, FILE *fp_plugin_input, FILE *fp_plugin_output, int trust_durations);
 
-extern int pluginsd_initialize_plugin_directories();
+int pluginsd_initialize_plugin_directories();
 
 
 
diff --git a/collectors/plugins.d/pluginsd_parser.h b/collectors/plugins.d/pluginsd_parser.h
index cdce32d928..3128873a04 100644
--- a/collectors/plugins.d/pluginsd_parser.h
+++ b/collectors/plugins.d/pluginsd_parser.h
@@ -22,22 +22,22 @@ typedef struct parser_user_object {
     void *private; // the user can set this for private use
 } PARSER_USER_OBJECT;
 
-extern PARSER_RC pluginsd_set_action(void *user, RRDSET *st, RRDDIM *rd, long long int value);
-extern PARSER_RC pluginsd_flush_action(void *user, RRDSET *st);
-extern PARSER_RC pluginsd_begin_action(void *user, RRDSET *st, usec_t microseconds, int trust_durations);
-extern PARSER_RC pluginsd_end_action(void *user, RRDSET *st);
-extern PARSER_RC pluginsd_chart_action(void *user, char *type, char *id, char *name, char *family, char *context,
+PARSER_RC pluginsd_set_action(void *user, RRDSET *st, RRDDIM *rd, long long int value);
+PARSER_RC pluginsd_flush_action(void *user, RRDSET *st);
+PARSER_RC pluginsd_begin_action(void *user, RRDSET *st, usec_t microseconds, int trust_durations);
+PARSER_RC pluginsd_end_action(void *user, RRDSET *st);
+PARSER_RC pluginsd_chart_action(void *user, char *type, char *id, char *name, char *family, char *context,
                                        char *title, char *units, char *plugin, char *module, int priority,
                                        int update_every, RRDSET_TYPE chart_type, char *options);
-extern PARSER_RC pluginsd_disable_action(void *user);
-extern PARSER_RC pluginsd_variable_action(void *user, RRDHOST *host, RRDSET *st, char *name, int global, NETDATA_DOUBLE value);
-extern PARSER_RC pluginsd_dimension_action(void *user, RRDSET *st, char *id, char *name, char *algorithm,
+PARSER_RC pluginsd_disable_action(void *user);
+PARSER_RC pluginsd_variable_action(void *user, RRDHOST *host, RRDSET *st, char *name, int global, NETDATA_DOUBLE value);
+PARSER_RC pluginsd_dimension_action(void *user, RRDSET *st, char *id, char *name, char *algorithm,
                                            long multiplier, long divisor, char *options, RRD_ALGORITHM algorithm_type);
-extern PARSER_RC pluginsd_label_action(void *user, char *key, char *value, RRDLABEL_SRC source);
-extern PARSER_RC pluginsd_overwrite_action(void *user, RRDHOST *host, DICTIONARY *new_host_labels);
+PARSER_RC pluginsd_label_action(void *user, char *key, char *value, RRDLABEL_SRC source);
+PARSER_RC pluginsd_overwrite_action(void *user, RRDHOST *host, DICTIONARY *new_host_labels);
 
-extern PARSER_RC pluginsd_function(char **words, void *user, PLUGINSD_ACTION  *plugins_action);
-extern PARSER_RC pluginsd_function_result_begin(char **words, void *user, PLUGINSD_ACTION  *plugins_action);
-extern void inflight_functions_init(PARSER *parser);
+PARSER_RC pluginsd_function(char **words, void *user, PLUGINSD_ACTION  *plugins_action);
+PARSER_RC pluginsd_function_result_begin(char **words, void *user, PLUGINSD_ACTION  *plugins_action);
+void inflight_functions_init(PARSER *parser);
 
 #endif //NETDATA_PLUGINSD_PARSER_H
diff --git a/collectors/proc.plugin/plugin_proc.h b/collectors/proc.plugin/plugin_proc.h
index 8cb5431e5f..cd10991e7a 100644
--- a/collectors/proc.plugin/plugin_proc.h
+++ b/collectors/proc.plugin/plugin_proc.h
@@ -9,58 +9,58 @@
 #define PLUGIN_PROC_NAME PLUGIN_PROC_CONFIG_NAME ".plugin"
 
 #define THREAD_NETDEV_NAME "PLUGIN[proc netdev]"
-extern void *netdev_main(void *ptr);
+void *netdev_main(void *ptr);
 
-extern int do_proc_net_wireless(int update_every, usec_t dt);
-extern int do_proc_diskstats(int update_every, usec_t dt);
-extern int do_proc_mdstat(int update_every, usec_t dt);
-extern int do_proc_net_snmp(int update_every, usec_t dt);
-extern int do_proc_net_snmp6(int update_every, usec_t dt);
-extern int do_proc_net_netstat(int update_every, usec_t dt);
-extern int do_proc_net_stat_conntrack(int update_every, usec_t dt);
-extern int do_proc_net_ip_vs_stats(int update_every, usec_t dt);
-extern int do_proc_stat(int update_every, usec_t dt);
-extern int do_proc_meminfo(int update_every, usec_t dt);
-extern int do_proc_vmstat(int update_every, usec_t dt);
-extern int do_proc_net_rpc_nfs(int update_every, usec_t dt);
-extern int do_proc_net_rpc_nfsd(int update_every, usec_t dt);
-extern int do_proc_sys_kernel_random_entropy_avail(int update_every, usec_t dt);
-extern int do_proc_interrupts(int update_every, usec_t dt);
-extern int do_proc_softirqs(int update_every, usec_t dt);
-extern int do_proc_pressure(int update_every, usec_t dt);
-extern int do_sys_kernel_mm_ksm(int update_every, usec_t dt);
-extern int do_sys_block_zram(int update_every, usec_t dt);
-extern int do_proc_loadavg(int update_every, usec_t dt);