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.

32 files changed, 172 insertions, 172 deletions

diff --git a/web/api/badges/web_buffer_svg.h b/web/api/badges/web_buffer_svg.h
index 4853a8864f..71857811fe 100644
--- a/web/api/badges/web_buffer_svg.h
+++ b/web/api/badges/web_buffer_svg.h
@@ -6,12 +6,12 @@
 #include "libnetdata/libnetdata.h"
 #include "web/server/web_client.h"
 
-extern void buffer_svg(BUFFER *wb, const char *label,
+void buffer_svg(BUFFER *wb, const char *label,
     NETDATA_DOUBLE value, const char *units, const char *label_color, const char *value_color, int precision, int scale, uint32_t options, int fixed_width_lbl, int fixed_width_val, const char* text_color_lbl, const char* text_color_val);
-extern char *format_value_and_unit(char *value_string, size_t value_string_len,
+char *format_value_and_unit(char *value_string, size_t value_string_len,
     NETDATA_DOUBLE value, const char *units, int precision);
 
-extern int web_client_api_request_v1_badge(struct rrdhost *host, struct web_client *w, char *url);
+int web_client_api_request_v1_badge(struct rrdhost *host, struct web_client *w, char *url);
 
 #include "web/api/web_api_v1.h"
 
diff --git a/web/api/exporters/allmetrics.h b/web/api/exporters/allmetrics.h
index f076ff0d56..3afc42e284 100644
--- a/web/api/exporters/allmetrics.h
+++ b/web/api/exporters/allmetrics.h
@@ -7,6 +7,6 @@
 #include "shell/allmetrics_shell.h"
 #include "web/server/web_client.h"
 
-extern int web_client_api_request_v1_allmetrics(RRDHOST *host, struct web_client *w, char *url);
+int web_client_api_request_v1_allmetrics(RRDHOST *host, struct web_client *w, char *url);
 
 #endif //NETDATA_API_ALLMETRICS_H
diff --git a/web/api/exporters/shell/allmetrics_shell.h b/web/api/exporters/shell/allmetrics_shell.h
index 1ee9aa717f..d6598e08d7 100644
--- a/web/api/exporters/shell/allmetrics_shell.h
+++ b/web/api/exporters/shell/allmetrics_shell.h
@@ -15,7 +15,7 @@
 #define ALLMETRICS_JSON                         3
 #define ALLMETRICS_PROMETHEUS_ALL_HOSTS         4
 
-extern void rrd_stats_api_v1_charts_allmetrics_json(RRDHOST *host, const char *filter_string, BUFFER *wb);
-extern void rrd_stats_api_v1_charts_allmetrics_shell(RRDHOST *host, const char *filter_string, BUFFER *wb);
+void rrd_stats_api_v1_charts_allmetrics_json(RRDHOST *host, const char *filter_string, BUFFER *wb);
+void rrd_stats_api_v1_charts_allmetrics_shell(RRDHOST *host, const char *filter_string, BUFFER *wb);
 
 #endif //NETDATA_API_ALLMETRICS_SHELL_H
diff --git a/web/api/formatters/charts2json.h b/web/api/formatters/charts2json.h
index 2d8cce3108..d4b04af585 100644
--- a/web/api/formatters/charts2json.h
+++ b/web/api/formatters/charts2json.h
@@ -5,8 +5,8 @@
 
 #include "rrd2json.h"
 
-extern void charts2json(RRDHOST *host, BUFFER *wb, int skip_volatile, int show_archived);
-extern void chartcollectors2json(RRDHOST *host, BUFFER *wb);
-extern const char* get_release_channel();
+void charts2json(RRDHOST *host, BUFFER *wb, int skip_volatile, int show_archived);
+void chartcollectors2json(RRDHOST *host, BUFFER *wb);
+const char* get_release_channel();
 
 #endif //NETDATA_API_FORMATTER_CHARTS2JSON_H
diff --git a/web/api/formatters/csv/csv.h b/web/api/formatters/csv/csv.h
index cf6020de4d..99aeb338d7 100644
--- a/web/api/formatters/csv/csv.h
+++ b/web/api/formatters/csv/csv.h
@@ -5,7 +5,7 @@
 
 #include "web/api/queries/rrdr.h"
 
-extern void rrdr2csv(RRDR *r, BUFFER *wb, uint32_t format, RRDR_OPTIONS options, const char *startline, const char *separator, const char *endline, const char *betweenlines, RRDDIM *temp_rd);
+void rrdr2csv(RRDR *r, BUFFER *wb, uint32_t format, RRDR_OPTIONS options, const char *startline, const char *separator, const char *endline, const char *betweenlines, RRDDIM *temp_rd);
 
 #include "../rrd2json.h"
 
diff --git a/web/api/formatters/json/json.h b/web/api/formatters/json/json.h
index 5c4e11371b..5f5e700820 100644
--- a/web/api/formatters/json/json.h
+++ b/web/api/formatters/json/json.h
@@ -5,6 +5,6 @@
 
 #include "../rrd2json.h"
 
-extern void rrdr2json(RRDR *r, BUFFER *wb, RRDR_OPTIONS options, int datatable, struct context_param *context_param_list);
+void rrdr2json(RRDR *r, BUFFER *wb, RRDR_OPTIONS options, int datatable, struct context_param *context_param_list);
 
 #endif //NETDATA_API_FORMATTER_JSON_H
diff --git a/web/api/formatters/json_wrapper.h b/web/api/formatters/json_wrapper.h
index bfadc883e6..e50f39d6d3 100644
--- a/web/api/formatters/json_wrapper.h
+++ b/web/api/formatters/json_wrapper.h
@@ -7,9 +7,9 @@
 #include "web/api/queries/query.h"
 
 
-extern void rrdr_json_wrapper_begin(RRDR *r, BUFFER *wb, uint32_t format, RRDR_OPTIONS options, int string_value,
+void rrdr_json_wrapper_begin(RRDR *r, BUFFER *wb, uint32_t format, RRDR_OPTIONS options, int string_value,
     RRDR_GROUPING group_method, QUERY_PARAMS *query_params);
-extern void rrdr_json_wrapper_anomaly_rates(RRDR *r, BUFFER *wb, uint32_t format, uint32_t options, int string_value);
-extern void rrdr_json_wrapper_end(RRDR *r, BUFFER *wb, uint32_t format, uint32_t options, int string_value);
+void rrdr_json_wrapper_anomaly_rates(RRDR *r, BUFFER *wb, uint32_t format, uint32_t options, int string_value);
+void rrdr_json_wrapper_end(RRDR *r, BUFFER *wb, uint32_t format, uint32_t options, int string_value);
 
 #endif //NETDATA_API_FORMATTER_JSON_WRAPPER_H
diff --git a/web/api/formatters/rrd2json.h b/web/api/formatters/rrd2json.h
index 6be53ff8a6..8f5f38f100 100644
--- a/web/api/formatters/rrd2json.h
+++ b/web/api/formatters/rrd2json.h
@@ -61,10 +61,10 @@ typedef struct query_params {
 #define DATASOURCE_FORMAT_CSV_JSON_ARRAY "csvjsonarray"
 #define DATASOURCE_FORMAT_CSV_MARKDOWN "markdown"
 
-extern void rrd_stats_api_v1_chart(RRDSET *st, BUFFER *wb);
-extern void rrdr_buffer_print_format(BUFFER *wb, uint32_t format);
+void rrd_stats_api_v1_chart(RRDSET *st, BUFFER *wb);
+void rrdr_buffer_print_format(BUFFER *wb, uint32_t format);
 
-extern int rrdset2anything_api_v1(
+int rrdset2anything_api_v1(
           ONEWAYALLOC *owa
         , RRDSET *st
         , QUERY_PARAMS *query_params
@@ -81,7 +81,7 @@ extern int rrdset2anything_api_v1(
         , int tier
 );
 
-extern int rrdset2value_api_v1(
+int rrdset2value_api_v1(
           RRDSET *st
         , BUFFER *wb
         , NETDATA_DOUBLE *n
@@ -104,8 +104,8 @@ extern int rrdset2value_api_v1(
         , int tier
 );
 
-extern void build_context_param_list(ONEWAYALLOC *owa, struct context_param **param_list, RRDSET *st);
-extern void rebuild_context_param_list(ONEWAYALLOC *owa, struct context_param *context_param_list, time_t after_requested);
-extern void free_context_param_list(ONEWAYALLOC *owa, struct context_param **param_list);
+void build_context_param_list(ONEWAYALLOC *owa, struct context_param **param_list, RRDSET *st);
+void rebuild_context_param_list(ONEWAYALLOC *owa, struct context_param *context_param_list, time_t after_requested);
+void free_context_param_list(ONEWAYALLOC *owa, struct context_param **param_list);
 
 #endif /* NETDATA_RRD2JSON_H */
diff --git a/web/api/formatters/rrdset2json.h b/web/api/formatters/rrdset2json.h
index 697c846347..b2908e225e 100644
--- a/web/api/formatters/rrdset2json.h
+++ b/web/api/formatters/rrdset2json.h
@@ -5,6 +5,6 @@
 
 #include "rrd2json.h"
 
-extern void rrdset2json(RRDSET *st, BUFFER *wb, size_t *dimensions_count, size_t *memory_used, int skip_volatile);
+void rrdset2json(RRDSET *st, BUFFER *wb, size_t *dimensions_count, size_t *memory_used, int skip_volatile);
 
 #endif //NETDATA_API_FORMATTER_RRDSET2JSON_H
diff --git a/web/api/formatters/ssv/ssv.h b/web/api/formatters/ssv/ssv.h
index 66716b9c9f..854fc1f88c 100644
--- a/web/api/formatters/ssv/ssv.h
+++ b/web/api/formatters/ssv/ssv.h
@@ -5,6 +5,6 @@
 
 #include "../rrd2json.h"
 
-extern void rrdr2ssv(RRDR *r, BUFFER *wb, RRDR_OPTIONS options, const char *prefix, const char *separator, const char *suffix, RRDDIM *temp_rd);
+void rrdr2ssv(RRDR *r, BUFFER *wb, RRDR_OPTIONS options, const char *prefix, const char *separator, const char *suffix, RRDDIM *temp_rd);
 
 #endif //NETDATA_API_FORMATTER_SSV_H
diff --git a/web/api/formatters/value/value.h b/web/api/formatters/value/value.h
index fc1c7bf08d..b9583803e8 100644
--- a/web/api/formatters/value/value.h
+++ b/web/api/formatters/value/value.h
@@ -5,6 +5,6 @@
 
 #include "../rrd2json.h"
 
-extern NETDATA_DOUBLE rrdr2value(RRDR *r, long i, RRDR_OPTIONS options, int *all_values_are_null, NETDATA_DOUBLE *anomaly_rate, RRDDIM *temp_rd);
+NETDATA_DOUBLE rrdr2value(RRDR *r, long i, RRDR_OPTIONS options, int *all_values_are_null, NETDATA_DOUBLE *anomaly_rate, RRDDIM *temp_rd);
 
 #endif //NETDATA_API_FORMATTER_VALUE_H
diff --git a/web/api/health/health_cmdapi.h b/web/api/health/health_cmdapi.h
index d8ec6aaa02..d5309c73ff 100644
--- a/web/api/health/health_cmdapi.h
+++ b/web/api/health/health_cmdapi.h
@@ -24,7 +24,7 @@
 #define HEALTH_CMDAPI_MSG_STYPEWARNING "WARNING: Added alarm selector to silence/disable alarms without a SILENCE or DISABLE command.\n"
 #define HEALTH_CMDAPI_MSG_NOSELECTORWARNING "WARNING: SILENCE or DISABLE command is ineffective without defining any alarm selectors.\n"
 
-extern int web_client_api_request_v1_mgmt_health(RRDHOST *host, struct web_client *w, char *url);
+int web_client_api_request_v1_mgmt_health(RRDHOST *host, struct web_client *w, char *url);
 
 #include "web/api/web_api_v1.h"
 
diff --git a/web/api/queries/average/average.h b/web/api/queries/average/average.h
index 55c51722c9..b319668860 100644
--- a/web/api/queries/average/average.h
+++ b/web/api/queries/average/average.h
@@ -6,10 +6,10 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_average(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_average(RRDR *r);
-extern void grouping_free_average(RRDR *r);
-extern void grouping_add_average(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_average(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_average(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_average(RRDR *r);
+void grouping_free_average(RRDR *r);
+void grouping_add_average(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_average(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERY_AVERAGE_H
diff --git a/web/api/queries/countif/countif.h b/web/api/queries/countif/countif.h
index 0c7d2d7d11..dfe8056589 100644
--- a/web/api/queries/countif/countif.h
+++ b/web/api/queries/countif/countif.h
@@ -6,10 +6,10 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_countif(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_countif(RRDR *r);
-extern void grouping_free_countif(RRDR *r);
-extern void grouping_add_countif(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_countif(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_countif(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_countif(RRDR *r);
+void grouping_free_countif(RRDR *r);
+void grouping_add_countif(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_countif(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERY_COUNTIF_H
diff --git a/web/api/queries/des/des.h b/web/api/queries/des/des.h
index 8906d14eb2..05fa01b349 100644
--- a/web/api/queries/des/des.h
+++ b/web/api/queries/des/des.h
@@ -6,12 +6,12 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_init_des(void);
+void grouping_init_des(void);
 
-extern void grouping_create_des(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_des(RRDR *r);
-extern void grouping_free_des(RRDR *r);
-extern void grouping_add_des(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_des(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_des(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_des(RRDR *r);
+void grouping_free_des(RRDR *r);
+void grouping_add_des(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_des(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERIES_DES_H
diff --git a/web/api/queries/incremental_sum/incremental_sum.h b/web/api/queries/incremental_sum/incremental_sum.h
index 6d908cef68..c24507fcf2 100644
--- a/web/api/queries/incremental_sum/incremental_sum.h
+++ b/web/api/queries/incremental_sum/incremental_sum.h
@@ -6,10 +6,10 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_incremental_sum(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_incremental_sum(RRDR *r);
-extern void grouping_free_incremental_sum(RRDR *r);
-extern void grouping_add_incremental_sum(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_incremental_sum(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_incremental_sum(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_incremental_sum(RRDR *r);
+void grouping_free_incremental_sum(RRDR *r);
+void grouping_add_incremental_sum(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_incremental_sum(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERY_INCREMENTAL_SUM_H
diff --git a/web/api/queries/max/max.h b/web/api/queries/max/max.h
index 28913686b1..e2427d26d4 100644
--- a/web/api/queries/max/max.h
+++ b/web/api/queries/max/max.h
@@ -6,10 +6,10 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_max(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_max(RRDR *r);
-extern void grouping_free_max(RRDR *r);
-extern void grouping_add_max(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_max(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_max(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_max(RRDR *r);
+void grouping_free_max(RRDR *r);
+void grouping_add_max(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_max(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERY_MAX_H
diff --git a/web/api/queries/median/median.h b/web/api/queries/median/median.h
index dd1b3de613..9fc159db42 100644
--- a/web/api/queries/median/median.h
+++ b/web/api/queries/median/median.h
@@ -6,18 +6,18 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_median(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median1(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median2(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median3(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median5(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median10(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median15(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median20(RRDR *r, const char *options);
-extern void grouping_create_trimmed_median25(RRDR *r, const char *options);
-extern void grouping_reset_median(RRDR *r);
-extern void grouping_free_median(RRDR *r);
-extern void grouping_add_median(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_median(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_median(RRDR *r, const char *options);
+void grouping_create_trimmed_median1(RRDR *r, const char *options);
+void grouping_create_trimmed_median2(RRDR *r, const char *options);
+void grouping_create_trimmed_median3(RRDR *r, const char *options);
+void grouping_create_trimmed_median5(RRDR *r, const char *options);
+void grouping_create_trimmed_median10(RRDR *r, const char *options);
+void grouping_create_trimmed_median15(RRDR *r, const char *options);
+void grouping_create_trimmed_median20(RRDR *r, const char *options);
+void grouping_create_trimmed_median25(RRDR *r, const char *options);
+void grouping_reset_median(RRDR *r);
+void grouping_free_median(RRDR *r);
+void grouping_add_median(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_median(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERIES_MEDIAN_H
diff --git a/web/api/queries/min/min.h b/web/api/queries/min/min.h
index b8627f6679..dcdfe252fc 100644
--- a/web/api/queries/min/min.h
+++ b/web/api/queries/min/min.h
@@ -6,10 +6,10 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_min(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_min(RRDR *r);
-extern void grouping_free_min(RRDR *r);
-extern void grouping_add_min(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_min(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_min(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_min(RRDR *r);
+void grouping_free_min(RRDR *r);
+void grouping_add_min(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_min(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERY_MIN_H
diff --git a/web/api/queries/percentile/percentile.h b/web/api/queries/percentile/percentile.h
index 709717ebd5..65e335c110 100644
--- a/web/api/queries/percentile/percentile.h
+++ b/web/api/queries/percentile/percentile.h
@@ -6,18 +6,18 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_percentile25(RRDR *r, const char *options);
-extern void grouping_create_percentile50(RRDR *r, const char *options);
-extern void grouping_create_percentile75(RRDR *r, const char *options);
-extern void grouping_create_percentile80(RRDR *r, const char *options);
-extern void grouping_create_percentile90(RRDR *r, const char *options);
-extern void grouping_create_percentile95(RRDR *r, const char *options);
-extern void grouping_create_percentile97(RRDR *r, const char *options);
-extern void grouping_create_percentile98(RRDR *r, const char *options);
-extern void grouping_create_percentile99(RRDR *r, const char *options );
-extern void grouping_reset_percentile(RRDR *r);
-extern void grouping_free_percentile(RRDR *r);
-extern void grouping_add_percentile(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_percentile(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_percentile25(RRDR *r, const char *options);
+void grouping_create_percentile50(RRDR *r, const char *options);
+void grouping_create_percentile75(RRDR *r, const char *options);
+void grouping_create_percentile80(RRDR *r, const char *options);
+void grouping_create_percentile90(RRDR *r, const char *options);
+void grouping_create_percentile95(RRDR *r, const char *options);
+void grouping_create_percentile97(RRDR *r, const char *options);
+void grouping_create_percentile98(RRDR *r, const char *options);
+void grouping_create_percentile99(RRDR *r, const char *options );
+void grouping_reset_percentile(RRDR *r);
+void grouping_free_percentile(RRDR *r);
+void grouping_add_percentile(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_percentile(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERIES_PERCENTILE_H
diff --git a/web/api/queries/query.h b/web/api/queries/query.h
index df876d9ac7..ebad5a1f8d 100644
--- a/web/api/queries/query.h
+++ b/web/api/queries/query.h
@@ -47,10 +47,10 @@ typedef enum rrdr_grouping {
     RRDR_GROUPING_COUNTIF,
 } RRDR_GROUPING;
 
-extern const char *group_method2string(RRDR_GROUPING group);
-extern void web_client_api_v1_init_grouping(void);
-extern RRDR_GROUPING web_client_api_request_v1_data_group(const char *name, RRDR_GROUPING def);
-extern const char *web_client_api_request_v1_data_group_to_string(RRDR_GROUPING group);
+const char *group_method2string(RRDR_GROUPING group);
+void web_client_api_v1_init_grouping(void);
+RRDR_GROUPING web_client_api_request_v1_data_group(const char *name, RRDR_GROUPING def);
+const char *web_client_api_request_v1_data_group_to_string(RRDR_GROUPING group);
 
 #ifdef __cplusplus
 }
diff --git a/web/api/queries/rrdr.h b/web/api/queries/rrdr.h
index ffc378193c..d431f7d055 100644
--- a/web/api/queries/rrdr.h
+++ b/web/api/queries/rrdr.h
@@ -128,20 +128,20 @@ typedef struct rrdresult {
 #define rrdr_rows(r) ((r)->rows)
 
 #include "database/rrd.h"
-extern void rrdr_free(ONEWAYALLOC *owa, RRDR *r);
-extern RRDR *rrdr_create(ONEWAYALLOC *owa, struct rrdset *st, long n, struct context_param *context_param_list);
-extern RRDR *rrdr_create_for_x_dimensions(ONEWAYALLOC *owa, int dimensions, long points);
+void rrdr_free(ONEWAYALLOC *owa, RRDR *r);
+RRDR *rrdr_create(ONEWAYALLOC *owa, struct rrdset *st, long n, struct context_param *context_param_list);
+RRDR *rrdr_create_for_x_dimensions(ONEWAYALLOC *owa, int dimensions, long points);
 
 #include "../web_api_v1.h"
 #include "web/api/queries/query.h"
 
-extern RRDR *rrd2rrdr(
+RRDR *rrd2rrdr(
     ONEWAYALLOC *owa,
     RRDSET *st, long points_wanted, long long after_wanted, long long before_wanted,
     RRDR_GROUPING group_method, long resampling_time_requested, RRDR_OPTIONS options, const char *dimensions,
     struct context_param *context_param_list, const char *group_options, int timeout, int tier);
 
-extern int rrdr_relative_window_to_absolute(long long *after, long long *before);
+int rrdr_relative_window_to_absolute(long long *after, long long *before);
 
 #ifdef __cplusplus
 }
diff --git a/web/api/queries/ses/ses.h b/web/api/queries/ses/ses.h
index 094b8de3fd..79b09fbdf8 100644
--- a/web/api/queries/ses/ses.h
+++ b/web/api/queries/ses/ses.h
@@ -6,12 +6,12 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_init_ses(void);
+void grouping_init_ses(void);
 
-extern void grouping_create_ses(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_ses(RRDR *r);
-extern void grouping_free_ses(RRDR *r);
-extern void grouping_add_ses(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_ses(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_ses(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_ses(RRDR *r);
+void grouping_free_ses(RRDR *r);
+void grouping_add_ses(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_ses(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERIES_SES_H
diff --git a/web/api/queries/stddev/stddev.h b/web/api/queries/stddev/stddev.h
index c5c91f88d4..4b8ffcd53c 100644
--- a/web/api/queries/stddev/stddev.h
+++ b/web/api/queries/stddev/stddev.h
@@ -6,13 +6,13 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_stddev(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_stddev(RRDR *r);
-extern void grouping_free_stddev(RRDR *r);
-extern void grouping_add_stddev(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_stddev(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
-extern NETDATA_DOUBLE grouping_flush_coefficient_of_variation(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
-// extern NETDATA_DOUBLE grouping_flush_mean(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
-// extern NETDATA_DOUBLE grouping_flush_variance(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_stddev(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_stddev(RRDR *r);
+void grouping_free_stddev(RRDR *r);
+void grouping_add_stddev(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_stddev(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+NETDATA_DOUBLE grouping_flush_coefficient_of_variation(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+// NETDATA_DOUBLE grouping_flush_mean(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+// NETDATA_DOUBLE grouping_flush_variance(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERIES_STDDEV_H
diff --git a/web/api/queries/sum/sum.h b/web/api/queries/sum/sum.h
index 4e7e396e95..8987827754 100644
--- a/web/api/queries/sum/sum.h
+++ b/web/api/queries/sum/sum.h
@@ -6,10 +6,10 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_sum(RRDR *r, const char *options __maybe_unused);
-extern void grouping_reset_sum(RRDR *r);
-extern void grouping_free_sum(RRDR *r);
-extern void grouping_add_sum(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_sum(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_sum(RRDR *r, const char *options __maybe_unused);
+void grouping_reset_sum(RRDR *r);
+void grouping_free_sum(RRDR *r);
+void grouping_add_sum(RRDR *r, NETDATA_DOUBLE value);
+NETDATA_DOUBLE grouping_flush_sum(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
 
 #endif //NETDATA_API_QUERY_SUM_H
diff --git a/web/api/queries/trimmed_mean/trimmed_mean.h b/web/api/queries/trimmed_mean/trimmed_mean.h
index 1a4f63e9c0..e66d925411 100644
--- a/web/api/queries/trimmed_mean/trimmed_mean.h
+++ b/web/api/queries/trimmed_mean/trimmed_mean.h
@@ -6,17 +6,17 @@
 #include "../query.h"
 #include "../rrdr.h"
 
-extern void grouping_create_trimmed_mean1(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean2(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean3(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean5(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean10(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean15(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean20(RRDR *r, const char *options);
-extern void grouping_create_trimmed_mean25(RRDR *r, const char *options);
-extern void grouping_reset_trimmed_mean(RRDR *r);
-extern void grouping_free_trimmed_mean(RRDR *r);
-extern void grouping_add_trimmed_mean(RRDR *r, NETDATA_DOUBLE value);
-extern NETDATA_DOUBLE grouping_flush_trimmed_mean(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr);
+void grouping_create_trimmed_mean1(RRDR *r, const char *options);