faster execution of external programs (#12759)

* faster invocation of external plugins by eliminating the need for starting /bin/sh and then the command

* added missing parameter

* prefer the z function

* cleanup and clarity - addressed LGTM issue

* simplified the popen() interface a bit, to make it more predictable for future uses

* removed commented old code

* more comments cleanup

* mypopen_raw() added for completeness - it is not currently used

* simplified the mypopen_raw() interface even further

* Update libnetdata/popen/popen.c

Co-authored-by: Vladimir Kobal <vlad@prokk.net>

* restored 0 flags for netdata_spawn() and cosmetic  changes

* added more clarity to the code and reverted old behavior of all other execution of commands

Co-authored-by: Vladimir Kobal <vlad@prokk.net>

2 files changed, 34 insertions, 21 deletions

diff --git a/collectors/cgroups.plugin/cgroup-network.c b/collectors/cgroups.plugin/cgroup-network.c
index 6465c91e74..bd7822609c 100644
--- a/collectors/cgroups.plugin/cgroup-network.c
+++ b/collectors/cgroups.plugin/cgroup-network.c
@@ -479,7 +479,17 @@ void call_the_helper(pid_t pid, const char *cgroup) {
     info("running: %s", command);
 
     pid_t cgroup_pid;
-    FILE *fp = mypopene(command, &cgroup_pid, environment);
+    FILE *fp;
+
+    if(cgroup) {
+        (void)mypopen_raw_default_flags(&cgroup_pid, environment, &fp, PLUGINS_DIR "/cgroup-network-helper.sh", "--cgroup", cgroup);
+    }
+    else {
+        char buffer[100];
+        snprintfz(buffer, sizeof(buffer) - 1, "%d", pid);
+        (void)mypopen_raw_default_flags(&cgroup_pid, environment, &fp, PLUGINS_DIR "/cgroup-network-helper.sh", "--pid", buffer);
+    }
+
     if(fp) {
         char buffer[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
         char *s;
@@ -643,8 +653,13 @@ int main(int argc, char **argv) {
     if(argc != 3)
         usage();
 
-    if(!strcmp(argv[1], "-p") || !strcmp(argv[1], "--pid")) {
-        pid = atoi(argv[2]);
+    int arg = 1;
+    int helper = 1;
+    if (getenv("KUBERNETES_SERVICE_HOST") != NULL && getenv("KUBERNETES_SERVICE_PORT") != NULL)
+        helper = 0;
+
+    if(!strcmp(argv[arg], "-p") || !strcmp(argv[arg], "--pid")) {
+        pid = atoi(argv[arg+1]);
 
         if(pid <= 0) {
             errno = 0;
@@ -652,17 +667,17 @@ int main(int argc, char **argv) {
             return 2;
         }
 
-        call_the_helper(pid, NULL);
+        if(helper) call_the_helper(pid, NULL);
     }
-    else if(!strcmp(argv[1], "--cgroup")) {
-        char *cgroup = argv[2];
+    else if(!strcmp(argv[arg], "--cgroup")) {
+        char *cgroup = argv[arg+1];
         if(verify_path(cgroup) == -1) {
             error("cgroup '%s' does not exist or is not valid.", cgroup);
             return 1;
         }
 
         pid = read_pid_from_cgroup(cgroup);
-        call_the_helper(pid, cgroup);
+        if(helper) call_the_helper(pid, cgroup);
 
         if(pid <= 0 && !detected_devices) {
             errno = 0;
diff --git a/collectors/cgroups.plugin/sys_fs_cgroup.c b/collectors/cgroups.plugin/sys_fs_cgroup.c
index 9ba249ca60..0ebfbcc8a9 100644
--- a/collectors/cgroups.plugin/sys_fs_cgroup.c
+++ b/collectors/cgroups.plugin/sys_fs_cgroup.c
@@ -1475,19 +1475,20 @@ static inline void read_cgroup_network_interfaces(struct cgroup *cg) {
     debug(D_CGROUP, "looking for the network interfaces of cgroup '%s' with chart id '%s' and title '%s'", cg->id, cg->chart_id, cg->chart_title);
 
     pid_t cgroup_pid;
-    char command[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
+    char cgroup_identifier[CGROUP_NETWORK_INTERFACE_MAX_LINE + 1];
 
     if(!(cg->options & CGROUP_OPTIONS_IS_UNIFIED)) {
-        snprintfz(command, CGROUP_NETWORK_INTERFACE_MAX_LINE, "exec %s --cgroup '%s%s'", cgroups_network_interface_script, cgroup_cpuacct_base, cg->id);
+        snprintfz(cgroup_identifier, CGROUP_NETWORK_INTERFACE_MAX_LINE, "%s%s", cgroup_cpuacct_base, cg->id);
     }
     else {
-        snprintfz(command, CGROUP_NETWORK_INTERFACE_MAX_LINE, "exec %s --cgroup '%s%s'", cgroups_network_interface_script, cgroup_unified_base, cg->id);
+        snprintfz(cgroup_identifier, CGROUP_NETWORK_INTERFACE_MAX_LINE, "%s%s", cgroup_unified_base, cg->id);
     }
 
-    debug(D_CGROUP, "executing command '%s' for cgroup '%s'", command, cg->id);
-    FILE *fp = mypopen(command, &cgroup_pid);
+    debug(D_CGROUP, "executing cgroup_identifier %s --cgroup '%s' for cgroup '%s'", cgroups_network_interface_script, cgroup_identifier, cg->id);
+    FILE *fp;
+    (void)mypopen_raw_default_flags_and_environment(&cgroup_pid, &fp, cgroups_network_interface_script, "--cgroup", cgroup_identifier);
     if(!fp) {
-        error("CGROUP: cannot popen(\"%s\", \"r\").", command);
+        error("CGROUP: cannot popen(%s --cgroup \"%s\", \"r\").", cgroups_network_interface_script, cgroup_identifier);
         return;
     }
 
@@ -1528,7 +1529,7 @@ static inline void read_cgroup_network_interfaces(struct cgroup *cg) {
     }
 
     mypclose(fp, cgroup_pid);
-    // debug(D_CGROUP, "closed command for cgroup '%s'", cg->id);
+    // debug(D_CGROUP, "closed cgroup_identifier for cgroup '%s'", cg->id);
 }
 
 static inline void free_cgroup_network_interfaces(struct cgroup *cg) {
@@ -1614,13 +1615,10 @@ static inline void cgroup_get_chart_name(struct cgroup *cg) {
     debug(D_CGROUP, "looking for the name of cgroup '%s' with chart id '%s' and title '%s'", cg->id, cg->chart_id, cg->chart_title);
 
     pid_t cgroup_pid;
-    char command[CGROUP_CHARTID_LINE_MAX + 1];
-
     // TODO: use cg->id when the renaming script is fixed
-    snprintfz(command, CGROUP_CHARTID_LINE_MAX, "exec %s '%s'", cgroups_rename_script, cg->intermediate_id);
-
-    debug(D_CGROUP, "executing command \"%s\" for cgroup '%s'", command, cg->chart_id);
-    FILE *fp = mypopen(command, &cgroup_pid);
+    debug(D_CGROUP, "executing command %s \"%s\" for cgroup '%s'", cgroups_rename_script, cg->intermediate_id, cg->chart_id);
+    FILE *fp;
+    (void)mypopen_raw_default_flags_and_environment(&cgroup_pid, &fp, cgroups_rename_script, cg->intermediate_id);
     if(fp) {
         // debug(D_CGROUP, "reading from command '%s' for cgroup '%s'", command, cg->id);
         char buffer[CGROUP_CHARTID_LINE_MAX + 1];
@@ -1661,7 +1659,7 @@ static inline void cgroup_get_chart_name(struct cgroup *cg) {
         }
     }
     else
-        error("CGROUP: cannot popen(\"%s\", \"r\").", command);
+        error("CGROUP: cannot popen(%s \"%s\", \"r\").", cgroups_rename_script, cg->intermediate_id);
 }
 
 static inline struct cgroup *cgroup_add(const char *id) {