Add native Go method for finding pids to procstat (#3559)

plugins/inputs/procstat/native_finder_notwindows.go

@@ -0,0 +1,59 @@
+// +build !windows
+
+package procstat
+
+import (
+	"regexp"
+
+	"github.com/shirou/gopsutil/process"
+)
+
+//Pattern matches on the process name
+func (pg *NativeFinder) Pattern(pattern string) ([]PID, error) {
+	var pids []PID
+	regxPattern, err := regexp.Compile(pattern)
+	if err != nil {
+		return pids, err
+	}
+	procs, err := process.Processes()
+	if err != nil {
+		return pids, err
+	}
+	for _, p := range procs {
+		name, err := p.Exe()
+		if err != nil {
+			//skip, this can be caused by the pid no longer existing
+			//or you having no permissions to access it
+			continue
+		}
+		if regxPattern.MatchString(name) {
+			pids = append(pids, PID(p.Pid))
+		}
+	}
+	return pids, err
+}
+
+//FullPattern matches on the command line when the proccess was executed
+func (pg *NativeFinder) FullPattern(pattern string) ([]PID, error) {
+	var pids []PID
+	regxPattern, err := regexp.Compile(pattern)
+	if err != nil {
+		return pids, err
+	}
+	procs, err := process.Processes()
+	if err != nil {
+		return pids, err
+	}
+	for _, p := range procs {
+		cmd, err := p.Cmdline()
+		if err != nil {
+			//skip, this can be caused by the pid no longer existing
+			//or you having no permissions to access it
+			continue
+		}
+		if regxPattern.MatchString(cmd) {
+			pids = append(pids, PID(p.Pid))
+		}
+	}
+	return pids, err
+}