modularized all source code (#4391)

* modularized all external plugins

* added README.md in plugins

* fixed title

* fixed typo

* relative link to external plugins

* external plugins configuration README

* added plugins link

* remove plugins link

* plugin names are links

* added links to external plugins

* removed unecessary spacing

* list to table

* added language

* fixed typo

* list to table on internal plugins

* added more documentation to internal plugins

* moved python, node, and bash code and configs into the external plugins

* added statsd README

* fix bug with corrupting config.h every 2nd compilation

* moved all config files together with their code

* more documentation

* diskspace info

* fixed broken links in apps.plugin

* added backends docs

* updated plugins readme

* move nc-backend.sh to backends

* created daemon directory

* moved all code outside src/

* fixed readme identation

* renamed plugins.d.plugin to plugins.d

* updated readme

* removed linux- from linux plugins

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* fixed README.md links

* fixed netdata tree links

* updated codacy, codeclimate and lgtm excluded paths

* update CMakeLists.txt

* updated automake options at top directory

* libnetdata slit into directories

* updated READMEs

* updated READMEs

* updated ARL docs

* updated ARL docs

* moved /plugins to /collectors

* moved all external plugins outside plugins.d

* updated codacy, codeclimate, lgtm

* updated README

* updated url

* updated readme

* updated readme

* updated readme

* updated readme

* moved api and web into webserver

* web/api web/gui web/server

* modularized webserver

* removed web/gui/version.txt

5 files changed, 1455 insertions, 0 deletions

diff --git a/streaming/Makefile.am b/streaming/Makefile.am
new file mode 100644
index 0000000000..84048948b4
--- /dev/null
+++ b/streaming/Makefile.am
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+dist_libconfig_DATA = \
+    stream.conf \
+    $(NULL)
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/streaming/README.md b/streaming/README.md
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/streaming/README.md
diff --git a/streaming/rrdpush.c b/streaming/rrdpush.c
new file mode 100644
index 0000000000..5d28206049
--- /dev/null
+++ b/streaming/rrdpush.c
@@ -0,0 +1,1227 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "rrdpush.h"
+
+/*
+ * rrdpush
+ *
+ * 3 threads are involved for all stream operations
+ *
+ * 1. a random data collection thread, calling rrdset_done_push()
+ *    this is called for each chart.
+ *
+ *    the output of this work is kept in a BUFFER in RRDHOST
+ *    the sender thread is signalled via a pipe (also in RRDHOST)
+ *
+ * 2. a sender thread running at the sending netdata
+ *    this is spawned automatically on the first chart to be pushed
+ *
+ *    It tries to push the metrics to the remote netdata, as fast
+ *    as possible (i.e. immediately after they are collected).
+ *
+ * 3. a receiver thread, running at the receiving netdata
+ *    this is spawned automatically when the sender connects to
+ *    the receiver.
+ *
+ */
+
+#define START_STREAMING_PROMPT "Hit me baby, push them over..."
+
+typedef enum {
+    RRDPUSH_MULTIPLE_CONNECTIONS_ALLOW,
+    RRDPUSH_MULTIPLE_CONNECTIONS_DENY_NEW
+} RRDPUSH_MULTIPLE_CONNECTIONS_STRATEGY;
+
+unsigned int default_rrdpush_enabled = 0;
+char *default_rrdpush_destination = NULL;
+char *default_rrdpush_api_key = NULL;
+char *default_rrdpush_send_charts_matching = NULL;
+
+int rrdpush_init() {
+    default_rrdpush_enabled     = (unsigned int)appconfig_get_boolean(&stream_config, CONFIG_SECTION_STREAM, "enabled", default_rrdpush_enabled);
+    default_rrdpush_destination = appconfig_get(&stream_config, CONFIG_SECTION_STREAM, "destination", "");
+    default_rrdpush_api_key     = appconfig_get(&stream_config, CONFIG_SECTION_STREAM, "api key", "");
+    default_rrdpush_send_charts_matching      = appconfig_get(&stream_config, CONFIG_SECTION_STREAM, "send charts matching", "*");
+    rrdhost_free_orphan_time    = config_get_number(CONFIG_SECTION_GLOBAL, "cleanup orphan hosts after seconds", rrdhost_free_orphan_time);
+
+    if(default_rrdpush_enabled && (!default_rrdpush_destination || !*default_rrdpush_destination || !default_rrdpush_api_key || !*default_rrdpush_api_key)) {
+        error("STREAM [send]: cannot enable sending thread - information is missing.");
+        default_rrdpush_enabled = 0;
+    }
+
+    return default_rrdpush_enabled;
+}
+
+#define CONNECTED_TO_SIZE 100
+
+// data collection happens from multiple threads
+// each of these threads calls rrdset_done()
+// which in turn calls rrdset_done_push()
+// which uses this pipe to notify the streaming thread
+// that there are more data ready to be sent
+#define PIPE_READ 0
+#define PIPE_WRITE 1
+
+// to have the remote netdata re-sync the charts
+// to its current clock, we send for this many
+// iterations a BEGIN line without microseconds
+// this is for the first iterations of each chart
+unsigned int remote_clock_resync_iterations = 60;
+
+#define rrdpush_buffer_lock(host) netdata_mutex_lock(&((host)->rrdpush_sender_buffer_mutex))
+#define rrdpush_buffer_unlock(host) netdata_mutex_unlock(&((host)->rrdpush_sender_buffer_mutex))
+
+static inline int should_send_chart_matching(RRDSET *st) {
+    if(unlikely(!rrdset_flag_check(st, RRDSET_FLAG_ENABLED))) {
+        rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_SEND);
+        rrdset_flag_set(st, RRDSET_FLAG_UPSTREAM_IGNORE);
+    }
+    else if(!rrdset_flag_check(st, RRDSET_FLAG_UPSTREAM_SEND|RRDSET_FLAG_UPSTREAM_IGNORE)) {
+        RRDHOST *host = st->rrdhost;
+
+        if(simple_pattern_matches(host->rrdpush_send_charts_matching, st->id) ||
+            simple_pattern_matches(host->rrdpush_send_charts_matching, st->name)) {
+            rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_IGNORE);
+            rrdset_flag_set(st, RRDSET_FLAG_UPSTREAM_SEND);
+        }
+        else {
+            rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_SEND);
+            rrdset_flag_set(st, RRDSET_FLAG_UPSTREAM_IGNORE);
+        }
+    }
+
+    return(rrdset_flag_check(st, RRDSET_FLAG_UPSTREAM_SEND));
+}
+
+// checks if the current chart definition has been sent
+static inline int need_to_send_chart_definition(RRDSET *st) {
+    rrdset_check_rdlock(st);
+
+    if(unlikely(!(rrdset_flag_check(st, RRDSET_FLAG_UPSTREAM_EXPOSED))))
+        return 1;
+
+    RRDDIM *rd;
+    rrddim_foreach_read(rd, st) {
+        if(unlikely(!rd->exposed)) {
+            #ifdef NETDATA_INTERNAL_CHECKS
+            info("host '%s', chart '%s', dimension '%s' flag 'exposed' triggered chart refresh to upstream", st->rrdhost->hostname, st->id, rd->id);
+            #endif
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+// sends the current chart definition
+static inline void rrdpush_send_chart_definition_nolock(RRDSET *st) {
+    RRDHOST *host = st->rrdhost;
+
+    rrdset_flag_set(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+
+    // send the chart
+    buffer_sprintf(
+            host->rrdpush_sender_buffer
+            , "CHART \"%s\" \"%s\" \"%s\" \"%s\" \"%s\" \"%s\" \"%s\" %ld %d \"%s %s %s %s\" \"%s\" \"%s\"\n"
+            , st->id
+            , st->name
+            , st->title
+            , st->units
+            , st->family
+            , st->context
+            , rrdset_type_name(st->chart_type)
+            , st->priority
+            , st->update_every
+            , rrdset_flag_check(st, RRDSET_FLAG_OBSOLETE)?"obsolete":""
+            , rrdset_flag_check(st, RRDSET_FLAG_DETAIL)?"detail":""
+            , rrdset_flag_check(st, RRDSET_FLAG_STORE_FIRST)?"store_first":""
+            , rrdset_flag_check(st, RRDSET_FLAG_HIDDEN)?"hidden":""
+            , (st->plugin_name)?st->plugin_name:""
+            , (st->module_name)?st->module_name:""
+    );
+
+    // send the dimensions
+    RRDDIM *rd;
+    rrddim_foreach_read(rd, st) {
+        buffer_sprintf(
+                host->rrdpush_sender_buffer
+                , "DIMENSION \"%s\" \"%s\" \"%s\" " COLLECTED_NUMBER_FORMAT " " COLLECTED_NUMBER_FORMAT " \"%s %s\"\n"
+                , rd->id
+                , rd->name
+                , rrd_algorithm_name(rd->algorithm)
+                , rd->multiplier
+                , rd->divisor
+                , rrddim_flag_check(rd, RRDDIM_FLAG_HIDDEN)?"hidden":""
+                , rrddim_flag_check(rd, RRDDIM_FLAG_DONT_DETECT_RESETS_OR_OVERFLOWS)?"noreset":""
+        );
+        rd->exposed = 1;
+    }
+
+    // send the chart local custom variables
+    RRDSETVAR *rs;
+    for(rs = st->variables; rs ;rs = rs->next) {
+        if(unlikely(rs->type == RRDVAR_TYPE_CALCULATED && rs->options & RRDVAR_OPTION_CUSTOM_CHART_VAR)) {
+            calculated_number *value = (calculated_number *) rs->value;
+
+            buffer_sprintf(
+                    host->rrdpush_sender_buffer
+                    , "VARIABLE CHART %s = " CALCULATED_NUMBER_FORMAT "\n"
+                    , rs->variable
+                    , *value
+            );
+        }
+    }
+
+    st->upstream_resync_time = st->last_collected_time.tv_sec + (remote_clock_resync_iterations * st->update_every);
+}
+
+// sends the current chart dimensions
+static inline void rrdpush_send_chart_metrics_nolock(RRDSET *st) {
+    RRDHOST *host = st->rrdhost;
+    buffer_sprintf(host->rrdpush_sender_buffer, "BEGIN \"%s\" %llu\n", st->id, (st->last_collected_time.tv_sec > st->upstream_resync_time)?st->usec_since_last_update:0);
+
+    RRDDIM *rd;
+    rrddim_foreach_read(rd, st) {
+        if(rd->updated && rd->exposed)
+            buffer_sprintf(host->rrdpush_sender_buffer
+                           , "SET \"%s\" = " COLLECTED_NUMBER_FORMAT "\n"
+                           , rd->id
+                           , rd->collected_value
+        );
+    }
+
+    buffer_strcat(host->rrdpush_sender_buffer, "END\n");
+}
+
+static void rrdpush_sender_thread_spawn(RRDHOST *host);
+
+void rrdset_push_chart_definition_now(RRDSET *st) {
+    RRDHOST *host = st->rrdhost;
+
+    if(unlikely(!host->rrdpush_send_enabled || !should_send_chart_matching(st)))
+        return;
+
+    rrdset_rdlock(st);
+    rrdpush_buffer_lock(host);
+    rrdpush_send_chart_definition_nolock(st);
+    rrdpush_buffer_unlock(host);
+    rrdset_unlock(st);
+}
+
+void rrdset_done_push(RRDSET *st) {
+    if(unlikely(!should_send_chart_matching(st)))
+        return;
+
+    RRDHOST *host = st->rrdhost;
+
+    rrdpush_buffer_lock(host);
+
+    if(unlikely(host->rrdpush_send_enabled && !host->rrdpush_sender_spawn))
+        rrdpush_sender_thread_spawn(host);
+
+    if(unlikely(!host->rrdpush_sender_buffer || !host->rrdpush_sender_connected)) {
+        if(unlikely(!host->rrdpush_sender_error_shown))
+            error("STREAM %s [send]: not ready - discarding collected metrics.", host->hostname);
+
+        host->rrdpush_sender_error_shown = 1;
+
+        rrdpush_buffer_unlock(host);
+        return;
+    }
+    else if(unlikely(host->rrdpush_sender_error_shown)) {
+        info("STREAM %s [send]: sending metrics...", host->hostname);
+        host->rrdpush_sender_error_shown = 0;
+    }
+
+    if(need_to_send_chart_definition(st))
+        rrdpush_send_chart_definition_nolock(st);
+
+    rrdpush_send_chart_metrics_nolock(st);
+
+    // signal the sender there are more data
+    if(host->rrdpush_sender_pipe[PIPE_WRITE] != -1 && write(host->rrdpush_sender_pipe[PIPE_WRITE], " ", 1) == -1)
+        error("STREAM %s [send]: cannot write to internal pipe", host->hostname);
+
+    rrdpush_buffer_unlock(host);
+}
+
+// ----------------------------------------------------------------------------
+// rrdpush sender thread
+
+static inline void rrdpush_sender_add_host_variable_to_buffer_nolock(RRDHOST *host, RRDVAR *rv) {
+    calculated_number *value = (calculated_number *)rv->value;
+
+    buffer_sprintf(
+            host->rrdpush_sender_buffer
+            , "VARIABLE HOST %s = " CALCULATED_NUMBER_FORMAT "\n"
+            , rv->name
+            , *value
+    );
+
+    debug(D_STREAM, "RRDVAR pushed HOST VARIABLE %s = " CALCULATED_NUMBER_FORMAT, rv->name, *value);
+}
+
+void rrdpush_sender_send_this_host_variable_now(RRDHOST *host, RRDVAR *rv) {
+    if(host->rrdpush_send_enabled && host->rrdpush_sender_spawn && host->rrdpush_sender_connected) {
+        rrdpush_buffer_lock(host);
+        rrdpush_sender_add_host_variable_to_buffer_nolock(host, rv);
+        rrdpush_buffer_unlock(host);
+    }
+}
+
+static int rrdpush_sender_thread_custom_host_variables_callback(void *rrdvar_ptr, void *host_ptr) {
+    RRDVAR *rv = (RRDVAR *)rrdvar_ptr;
+    RRDHOST *host = (RRDHOST *)host_ptr;
+
+    if(unlikely(rv->options & RRDVAR_OPTION_CUSTOM_HOST_VAR && rv->type == RRDVAR_TYPE_CALCULATED)) {
+        rrdpush_sender_add_host_variable_to_buffer_nolock(host, rv);
+
+        // return 1, so that the traversal will return the number of variables sent
+        return 1;
+    }
+
+    // returning a negative number will break the traversal
+    return 0;
+}
+
+static void rrdpush_sender_thread_send_custom_host_variables(RRDHOST *host) {
+    int ret = rrdvar_callback_for_all_host_variables(host, rrdpush_sender_thread_custom_host_variables_callback, host);
+    debug(D_STREAM, "RRDVAR sent %d VARIABLES", ret);
+}
+
+// resets all the chart, so that their definitions
+// will be resent to the central netdata
+static void rrdpush_sender_thread_reset_all_charts(RRDHOST *host) {
+    rrdhost_rdlock(host);
+
+    RRDSET *st;
+    rrdset_foreach_read(st, host) {
+        rrdset_flag_clear(st, RRDSET_FLAG_UPSTREAM_EXPOSED);
+
+        st->upstream_resync_time = 0;
+
+        rrdset_rdlock(st);
+
+        RRDDIM *rd;
+        rrddim_foreach_read(rd, st)
+            rd->exposed = 0;
+
+        rrdset_unlock(st);
+    }
+
+    rrdhost_unlock(host);
+}
+
+static inline void rrdpush_sender_thread_data_flush(RRDHOST *host) {
+    rrdpush_buffer_lock(host);
+
+    if(buffer_strlen(host->rrdpush_sender_buffer))
+        error("STREAM %s [send]: discarding %zu bytes of metrics already in the buffer.", host->hostname, buffer_strlen(host->rrdpush_sender_buffer));
+
+    buffer_flush(host->rrdpush_sender_buffer);
+
+    rrdpush_sender_thread_reset_all_charts(host);
+    rrdpush_sender_thread_send_custom_host_variables(host);
+
+    rrdpush_buffer_unlock(host);
+}
+
+void rrdpush_sender_thread_stop(RRDHOST *host) {
+    rrdpush_buffer_lock(host);
+    rrdhost_wrlock(host);
+
+    netdata_thread_t thr = 0;
+
+    if(host->rrdpush_sender_spawn) {
+        info("STREAM %s [send]: signaling sending thread to stop...", host->hostname);
+
+        // signal the thread that we want to join it
+        host->rrdpush_sender_join = 1;
+
+        // copy the thread id, so that we will be waiting for the right one
+        // even if a new one has been spawn
+        thr = host->rrdpush_sender_thread;
+
+        // signal it to cancel
+        netdata_thread_cancel(host->rrdpush_sender_thread);
+    }
+
+    rrdhost_unlock(host);
+    rrdpush_buffer_unlock(host);
+
+    if(thr != 0) {
+        info("STREAM %s [send]: waiting for the sending thread to stop...", host->hostname);
+        void *result;
+        netdata_thread_join(thr, &result);
+        info("STREAM %s [send]: sending thread has exited.", host->hostname);
+    }
+}
+
+static inline void rrdpush_sender_thread_close_socket(RRDHOST *host) {
+    host->rrdpush_sender_connected = 0;
+
+    if(host->rrdpush_sender_socket != -1) {
+        close(host->rrdpush_sender_socket);
+        host->rrdpush_sender_socket = -1;
+    }
+}
+
+static int rrdpush_sender_thread_connect_to_master(RRDHOST *host, int default_port, int timeout, size_t *reconnects_counter, char *connected_to, size_t connected_to_size) {
+    struct timeval tv = {
+            .tv_sec = timeout,
+            .tv_usec = 0
+    };
+
+    // make sure the socket is closed
+    rrdpush_sender_thread_close_socket(host);
+
+    debug(D_STREAM, "STREAM: Attempting to connect...");
+    info("STREAM %s [send to %s]: connecting...", host->hostname, host->rrdpush_send_destination);
+
+    host->rrdpush_sender_socket = connect_to_one_of(
+            host->rrdpush_send_destination
+            , default_port
+            , &tv
+            , reconnects_counter
+            , connected_to
+            , connected_to_size
+    );
+
+    if(unlikely(host->rrdpush_sender_socket == -1)) {
+        error("STREAM %s [send to %s]: failed to connect", host->hostname, host->rrdpush_send_destination);
+        return 0;
+    }
+
+    info("STREAM %s [send to %s]: initializing communication...", host->hostname, connected_to);
+
+    #define HTTP_HEADER_SIZE 8192
+    char http[HTTP_HEADER_SIZE + 1];
+    snprintfz(http, HTTP_HEADER_SIZE,
+            "STREAM key=%s&hostname=%s&registry_hostname=%s&machine_guid=%s&update_every=%d&os=%s&timezone=%s&tags=%s HTTP/1.1\r\n"
+                    "User-Agent: %s/%s\r\n"
+                    "Accept: */*\r\n\r\n"
+              , host->rrdpush_send_api_key
+              , host->hostname
+              , host->registry_hostname
+              , host->machine_guid
+              , default_rrd_update_every
+              , host->os
+              , host->timezone
+              , (host->tags)?host->tags:""
+              , host->program_name
+              , host->program_version
+    );
+
+    if(send_timeout(host->rrdpush_sender_socket, http, strlen(http), 0, timeout) == -1) {
+        error("STREAM %s [send to %s]: failed to send HTTP header to remote netdata.", host->hostname, connected_to);
+        rrdpush_sender_thread_close_socket(host);
+        return 0;
+    }
+
+    info("STREAM %s [send to %s]: waiting response from remote netdata...", host->hostname, connected_to);
+
+    if(recv_timeout(host->rrdpush_sender_socket, http, HTTP_HEADER_SIZE, 0, timeout) == -1) {
+        error("STREAM %s [send to %s]: remote netdata does not respond.", host->hostname, connected_to);
+        rrdpush_sender_thread_close_socket(host);
+        return 0;
+    }
+
+    if(strncmp(http, START_STREAMING_PROMPT, strlen(START_STREAMING_PROMPT)) != 0) {
+        error("STREAM %s [send to %s]: server is not replying properly (is it a netdata?).", host->hostname, connected_to);
+        rrdpush_sender_thread_close_socket(host);
+        return 0;
+    }
+
+    info("STREAM %s [send to %s]: established communication - ready to send metrics...", host->hostname, connected_to);
+
+    if(sock_setnonblock(host->rrdpush_sender_socket) < 0)
+        error("STREAM %s [send to %s]: cannot set non-blocking mode for socket.", host->hostname, connected_to);
+
+    if(sock_enlarge_out(host->rrdpush_sender_socket) < 0)
+        error("STREAM %s [send to %s]: cannot enlarge the socket buffer.", host->hostname, connected_to);
+
+    debug(D_STREAM, "STREAM: Connected on fd %d...", host->rrdpush_sender_socket);
+
+    return 1;
+}
+
+static void rrdpush_sender_thread_cleanup_callback(void *ptr) {
+    RRDHOST *host = (RRDHOST *)ptr;
+
+    rrdpush_buffer_lock(host);
+    rrdhost_wrlock(host);
+
+    info("STREAM %s [send]: sending thread cleans up...", host->hostname);
+
+    rrdpush_sender_thread_close_socket(host);
+
+    // close the pipe
+    if(host->rrdpush_sender_pipe[PIPE_READ] != -1) {
+        close(host->rrdpush_sender_pipe[PIPE_READ]);
+        host->rrdpush_sender_pipe[PIPE_READ] = -1;
+    }
+
+    if(host->rrdpush_sender_pipe[PIPE_WRITE] != -1) {
+        close(host->rrdpush_sender_pipe[PIPE_WRITE]);
+        host->rrdpush_sender_pipe[PIPE_WRITE] = -1;
+    }
+
+    buffer_free(host->rrdpush_sender_buffer);
+    host->rrdpush_sender_buffer = NULL;
+
+    if(!host->rrdpush_sender_join) {
+        info("STREAM %s [send]: sending thread detaches itself.", host->hostname);
+        netdata_thread_detach(netdata_thread_self());
+    }
+
+    host->rrdpush_sender_spawn = 0;
+
+    info("STREAM %s [send]: sending thread now exits.", host->hostname);
+
+    rrdhost_unlock(host);
+    rrdpush_buffer_unlock(host);
+}
+
+void *rrdpush_sender_thread(void *ptr) {
+    RRDHOST *host = (RRDHOST *)ptr;
+
+    if(!host->rrdpush_send_enabled || !host->rrdpush_send_destination || !*host->rrdpush_send_destination || !host->rrdpush_send_api_key || !*host->rrdpush_send_api_key) {
+        error("STREAM %s [send]: thread created (task id %d), but host has streaming disabled.", host->hostname, gettid());
+        return NULL;
+    }
+
+    info("STREAM %s [send]: thread created (task id %d)", host->hostname, gettid());
+
+    int timeout = (int)appconfig_get_number(&stream_config, CONFIG_SECTION_STREAM, "timeout seconds", 60);
+    int default_port = (int)appconfig_get_number(&stream_config, CONFIG_SECTION_STREAM, "default port", 19999);
+    size_t max_size = (size_t)appconfig_get_number(&stream_config, CONFIG_SECTION_STREAM, "buffer size bytes", 1024 * 1024);
+    unsigned int reconnect_delay = (unsigned int)appconfig_get_number(&stream_config, CONFIG_SECTION_STREAM, "reconnect delay seconds", 5);
+    remote_clock_resync_iterations = (unsigned int)appconfig_get_number(&stream_config, CONFIG_SECTION_STREAM, "initial clock resync iterations", remote_clock_resync_iterations);
+    char connected_to[CONNECTED_TO_SIZE + 1] = "";
+
+    // initialize rrdpush globals
+    host->rrdpush_sender_buffer = buffer_create(1);
+    host->rrdpush_sender_connected = 0;
+    if(pipe(host->rrdpush_sender_pipe) == -1) fatal("STREAM %s [send]: cannot create required pipe.", host->hostname);
+
+    // initialize local variables
+    size_t begin = 0;
+    size_t reconnects_counter = 0;
+    size_t sent_bytes = 0;
+    size_t sent_bytes_on_this_connection = 0;
+
+
+    time_t last_sent_t = 0;
+    struct pollfd fds[2], *ifd, *ofd;
+    nfds_t fdmax;
+
+    ifd = &fds[0];
+    ofd = &fds[1];
+
+    size_t not_connected_loops = 0;
+
+    netdata_thread_cleanup_push(rrdpush_sender_thread_cleanup_callback, host);
+
+        for(; host->rrdpush_send_enabled && !netdata_exit ;) {
+            // check for outstanding cancellation requests
+            netdata_thread_testcancel();
+
+            // if we don't have socket open, lets wait a bit
+            if(unlikely(host->rrdpush_sender_socket == -1)) {
+                if(not_connected_loops == 0 && sent_bytes_on_this_connection > 0) {
+                    // fast re-connection on first disconnect
+                    sleep_usec(USEC_PER_MS * 500); // milliseconds
+                }
+                else {
+                    // slow re-connection on repeating errors
+                    sleep_usec(USEC_PER_SEC * reconnect_delay); // seconds
+                }
+
+                if(rrdpush_sender_thread_connect_to_master(host, default_port, timeout, &reconnects_counter, connected_to, CONNECTED_TO_SIZE)) {
+                    last_sent_t = now_monotonic_sec();
+
+                    // reset the buffer, to properly send charts and metrics
+                    rrdpush_sender_thread_data_flush(host);
+
+                    // make sure the next reconnection will be immediate
+                    not_connected_loops = 0;
+
+                    // reset the bytes we have sent for this session
+                    sent_bytes_on_this_connection = 0;
+
+                    // let the data collection threads know we are ready
+                    host->rrdpush_sender_connected = 1;
+                }
+                else {
+                    // increase the failed connections counter
+                    not_connected_loops++;
+
+                    // reset the number of bytes sent
+                    sent_bytes_on_this_connection = 0;
+                }
+
+                // loop through
+                continue;
+            }
+            else if(unlikely(now_monotonic_sec() - last_sent_t > timeout)) {
+                error("STREAM %s [send to %s]: could not send metrics for %d seconds - closing connection - we have sent %zu bytes on this connection.", host->hostname, connected_to, timeout, sent_bytes_on_this_connection);
+                rrdpush_sender_thread_close_socket(host);
+            }
+
+            ifd->fd = host->rrdpush_sender_pipe[PIPE_READ];
+            ifd->events = POLLIN;
+            ifd->revents = 0;
+
+            ofd->fd = host->rrdpush_sender_socket;
+            ofd->revents = 0;
+            if(ofd->fd != -1 && begin < buffer_strlen(host->rrdpush_sender_buffer)) {
+                debug(D_STREAM, "STREAM: Requesting data output on streaming socket %d...", ofd->fd);
+                ofd->events = POLLOUT;
+                fdmax = 2;
+            }
+            else {
+                debug(D_STREAM, "STREAM: Not requesting data output on streaming socket %d (nothing to send now)...", ofd->fd);
+                ofd->events = 0;
+                fdmax = 1;
+            }
+
+            debug(D_STREAM, "STREAM: Waiting for poll() events (current buffer length %zu bytes)...", buffer_strlen(host->rrdpush_sender_buffer));
+            if(unlikely(netdata_exit)) break;
+            int retval = poll(fds, fdmax, 1000);
+            if(unlikely(netdata_exit)) break;
+
+            if(unlikely(retval == -1)) {
+                debug(D_STREAM, "STREAM: poll() failed (current buffer length %zu bytes)...", buffer_strlen(host->rrdpush_sender_buffer));
+
+                if(errno == EAGAIN || errno == EINTR) {
+                    debug(D_STREAM, "STREAM: poll() failed with EAGAIN or EINTR...");
+                }
+                else {
+                    error("STREAM %s [send to %s]: failed to poll(). Closing socket.", host->hostname, connected_to);
+                    rrdpush_sender_thread_close_socket(host);
+                }
+
+                continue;
+            }
+            else if(likely(retval)) {
+                if (ifd->revents & POLLIN || ifd->revents & POLLPRI) {
+                    debug(D_STREAM, "STREAM: Data added to send buffer (current buffer length %zu bytes)...", buffer_strlen(host->rrdpush_sender_buffer));
+
+                    char buffer[1000 + 1];
+                    if (read(host->rrdpush_sender_pipe[PIPE_READ], buffer, 1000) == -1)
+                        error("STREAM %s [send to %s]: cannot read from internal pipe.", host->hostname, connected_to);
+                }
+
+                if (ofd->revents & POLLOUT) {
+                    if (begin < buffer_strlen(host->rrdpush_sender_buffer)) {
+                        debug(D_STREAM, "STREAM: Sending data (current buffer length %zu bytes, begin = %zu)...", buffer_strlen(host->rrdpush_sender_buffer), begin);
+
+                        // BEGIN RRDPUSH LOCKED SESSION
+
+                        // during this session, data collectors
+                        // will not be able to append data to our buffer
+                        // but the socket is in non-blocking mode
+                        // so, we will not block at send()
+
+                        netdata_thread_disable_cancelability();
+
+                        debug(D_STREAM, "STREAM: Getting exclusive lock on host...");
+                        rrdpush_buffer_lock(host);
+
+                        debug(D_STREAM, "STREAM: Sending data, starting from %zu, size %zu...", begin, buffer_strlen(host->rrdpush_sender_buffer));
+                        ssize_t ret = send(host->rrdpush_sender_socket, &host->rrdpush_sender_buffer->buffer[begin], buffer_strlen(host->rrdpush_sender_buffer) - begin, MSG_DONTWAIT);
+                        if (unlikely(ret == -1)) {
+                            if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) {
+                                debug(D_STREAM, "STREAM: Send failed - closing socket...");
+                                error("STREAM %s [send to %s]: failed to send metrics - closing connection - we have sent %zu bytes on this connection.", host->hostname, connected_to, sent_bytes_on_this_connection);
+                                rrdpush_sender_thread_close_socket(host);
+                            }
+                            else {
+                                debug(D_STREAM, "STREAM: Send failed - will retry...");
+                            }
+                        }
+                        else if (likely(ret > 0)) {
+                            // DEBUG - dump the string to see it
+                            //char c = host->rrdpush_sender_buffer->buffer[begin + ret];
+                            //host->rrdpush_sender_buffer->buffer[begin + ret] = '\0';
+                            //debug(D_STREAM, "STREAM: sent from %zu to %zd:\n%s\n", begin, ret, &host->rrdpush_sender_buffer->buffer[begin]);
+                            //host->rrdpush_sender_buffer->buffer[begin + ret] = c;
+
+                            sent_bytes_on_this_connection += ret;
+                            sent_bytes += ret;
+                            begin += ret;
+
+                            if (begin == buffer_strlen(host->rrdpush_sender_buffer)) {
+                                // we send it all
+
+                                debug(D_STREAM, "STREAM: Sent %zd bytes (the whole buffer)...", ret);
+                                buffer_flush(host->rrdpush_sender_buffer);
+                                begin = 0;
+                            }
+                            else {
+                                debug(D_STREAM, "STREAM: Sent %zd bytes (part of the data buffer)...", ret);
+                            }
+
+                            last_sent_t = now_monotonic_sec();
+                        }
+                        else {
+                            debug(D_STREAM, "STREAM: send() returned %zd - closing the socket...", ret);
+                            error("STREAM %s [send to %s]: failed to send metrics (send() returned %zd) - closing connection - we have sent %zu bytes on this connection.",
+                                  host->hostname, connected_to, ret, sent_bytes_on_this_connection);
+                            rrdpush_sender_thread_close_socket(host);
+                        }
+
+                        debug(D_STREAM, "STREAM: Releasing exclusive lock on host...");
+                        rrdpush_buffer_unlock(host);
+
+                        netdata_thread_enable_cancelability();
+
+                        // END RRDPUSH LOCKED SESSION
+                    }
+                    else {
+                        debug(D_STREAM, "STREAM: we have sent the entire buffer, but we received POLLOUT...");
+                    }
+                }
+
+                if(host->rrdpush_sender_socket != -1) {
+                    char *error = NULL;
+                    
+                    if (unlikely(ofd->revents & POLLERR))
+                        error = "socket reports errors (POLLERR)";
+                        
+                    else if (unlikely(ofd->revents & POLLHUP))
+                        error = "connection closed by remote end (POLLHUP)";
+                        
+                    else if (unlikely(ofd->revents & POLLNVAL))
+                        error = "connection is invalid (POLLNVAL)";
+                    
+                    if(unlikely(error)) {
+                        debug(D_STREAM, "STREAM: %s - closing socket...", error);
+                        error("STREAM %s [send to %s]: %s - reopening socket - we have sent %zu bytes on this connection.", host->hostname, connected_to, error, sent_bytes_on_this_connection);
+                        rrdpush_sender_thread_close_socket(host);
+                    }
+                }
+            }
+            else {
+                debug(D_STREAM, "STREAM: poll() timed out.");
+            }
+
+            // protection from overflow
+            if(buffer_strlen(host->rrdpush_sender_buffer) > max_size) {
+                debug(D_STREAM, "STREAM: Buffer is too big (%zu bytes), bigger than the max (%zu) - flushing it...", buffer_strlen(host->rrdpush_sender_buffer), max_size);
+                errno = 0;
+                error("STREAM %s [send to %s]: too many data pending - buffer is %zu bytes long, %zu unsent - we have sent %zu bytes in total, %zu on this connection. Closing connection to flush the data.", host->hostname, connected_to, host->rrdpush_sender_buffer->len, host->rrdpush_sender_buffer->len - begin, sent_bytes, sent_bytes_on_this_connection);
+                rrdpush_sender_thread_close_socket(host);
+            }
+        }
+
+    netdata_thread_cleanup_pop(1);
+    return NULL;
+}
+
+
+// ----------------------------------------------------------------------------
+// rrdpush receiver thread
+
+static void log_stream_connection(const char *client_ip, const char *client_port, const char *api_key, const char *machine_guid, const char *host, const char *msg) {
+    log_access("STREAM: %d '[%s]:%s' '%s' host '%s' api key '%s' machine guid '%s'", gettid(), client_ip, client_port, msg, host, api_key, machine_guid);
+}
+
+static RRDPUSH_MULTIPLE_CONNECTIONS_STRATEGY get_multiple_connections_strategy(struct config *c, const char *section, const char *name, RRDPUSH_MULTIPLE_CONNECTIONS_STRATEGY def) {
+    char *value;
+    switch(def) {
+        default:
+        case RRDPUSH_MULTIPLE_CONNECTIONS_ALLOW:
+            value = "allow";
+            break;
+
+        case RRDPUSH_MULTIPLE_CONNECTIONS_DENY_NEW:
+            value = "deny";
+            break;
+    }
+
+    value = appconfig_get(c, section, name, value);
+
+    RRDPUSH_MULTIPLE_CONNECTIONS_STRATEGY ret = def;
+
+    if(strcasecmp(value, "allow") == 0 || strcasecmp(value, "permit") == 0 || strcasecmp(value, "accept") == 0)
+        ret = RRDPUSH_MULTIPLE_CONNECTIONS_ALLOW;
+
+    else if(strcasecmp(value, "deny") == 0 || strcasecmp(value, "reject") == 0 || strcasecmp(value, "block") == 0)
+        ret = RRDPUSH_MULTIPLE_CONNECTIONS_DENY_NEW;
+
+    else
+        error("Invalid stream config value at section [%s], setting '%s', value '%s'", section, name, value);
+
+    return ret;
+}
+
+static int rrdpush_receive(int fd
+                           , const char *key
+                           , const char *hostname
+                           , const char *registry_hostname
+                           , const char *machine_guid
+                           , const char *os
+                           , const char *timezone
+                           , const char *tags
+                           , const char *program_name
+                           , const char *program_version
+                           , int update_every
+                           , char *client_ip
+                           , char *client_port
+) {
+    RRDHOST *host;
+    int history = default_rrd_history_entries;
+    RRD_MEMORY_MODE mode = default_rrd_memory_mode;
+    int health_enabled = default_health_enabled;
+    int rrdpush_enabled = default_rrdpush_enabled;
+    char *rrdpush_destination = default_rrdpush_destination;
+    char *rrdpush_api_key = default_rrdpush_api_key;
+    char *rrdpush_send_charts_matching = default_rrdpush_send_charts_matching;
+    time_t alarms_delay = 60;
+    RRDPUSH_MULTIPLE_CONNECTIONS_STRATEGY rrdpush_multiple_connections_strategy = RRDPUSH_MULTIPLE_CONNECTIONS_ALLOW;
+
+    update_every = (int)appconfig_get_number(&stream_config, machine_guid, "update every", update_every);
+    if(update_every < 0) update_every = 1;
+
+    history = (int)appconfig_get_number(&stream_confi