Refactor globpath pkg to return a map

this is so that we don't call os.Stat twice for every file matched
by Match(). Also changing the behavior to _not_ return the name of a
file that doesn't exist if it's not a glob.

internal/globpath/globpath.go

@@ -39,20 +39,25 @@ func Compile(path string) (*GlobPath, error) {
 	return &out, nil
 }
 
-func (g *GlobPath) Match() []string {
+func (g *GlobPath) Match() map[string]os.FileInfo {
 	if !g.hasMeta {
-		return []string{g.path}
+		out := make(map[string]os.FileInfo)
+		info, err := os.Stat(g.path)
+		if !os.IsNotExist(err) {
+			out[g.path] = info
+		}
+		return out
 	}
 	return walkFilePath(g.root, g.g)
 }
 
 // walk the filepath from the given root and return a list of files that match
 // the given glob.
-func walkFilePath(root string, g glob.Glob) []string {
+func walkFilePath(root string, g glob.Glob) map[string]os.FileInfo {
-	matchedFiles := []string{}
+	matchedFiles := make(map[string]os.FileInfo)
-	walkfn := func(path string, _ os.FileInfo, _ error) error {
+	walkfn := func(path string, info os.FileInfo, _ error) error {
 		if g.Match(path) {
-			matchedFiles = append(matchedFiles, path)
+			matchedFiles[path] = info
 		}
 		return nil
 	}

internal/globpath/globpath_test.go

@@ -11,12 +11,21 @@ import (
 
 func TestCompileAndMatch(t *testing.T) {
 	dir := getTestdataDir()
+	// test super asterisk
 	g1, err := Compile(dir + "/**")
 	require.NoError(t, err)
+	// test single asterisk
 	g2, err := Compile(dir + "/*.log")
 	require.NoError(t, err)
+	// test no meta characters (file exists)
 	g3, err := Compile(dir + "/log1.log")
 	require.NoError(t, err)
+	// test file that doesn't exist
+	g4, err := Compile(dir + "/i_dont_exist.log")
+	require.NoError(t, err)
+	// test super asterisk that doesn't exist
+	g5, err := Compile(dir + "/dir_doesnt_exist/**")
+	require.NoError(t, err)
 
 	matches := g1.Match()
 	assert.Len(t, matches, 3)
@@ -24,6 +33,10 @@ func TestCompileAndMatch(t *testing.T) {
 	assert.Len(t, matches, 2)
 	matches = g3.Match()
 	assert.Len(t, matches, 1)
+	matches = g4.Match()
+	assert.Len(t, matches, 0)
+	matches = g5.Match()
+	assert.Len(t, matches, 0)
 }
 
 func TestFindRootDir(t *testing.T) {

plugins/inputs/filestat/filestat.go

@@ -55,31 +55,29 @@ func (f *FileStat) Gather(acc telegraf.Accumulator) error {
 			f.globs[filepath] = g
 		}
 
-		for _, file := range g.Match() {
+		files := g.Match()
+		if len(files) == 0 {
+			acc.AddFields("filestat",
+				map[string]interface{}{
+					"exists": int64(0),
+				},
+				map[string]string{
+					"file": filepath,
+				})
+			continue
+		}
+
+		for fileName, fileInfo := range files {
 			tags := map[string]string{
-				"file": file,
+				"file": fileName,
 			}
 			fields := map[string]interface{}{
-				"exists": int64(0),
+				"exists":     int64(1),
+				"size_bytes": fileInfo.Size(),
 			}
-			// Get file stats
-			fileInfo, err := os.Stat(file)
-			if os.IsNotExist(err) {
-				// file doesn't exist, so move on to the next
-				acc.AddFields("filestat", fields, tags)
-				continue
-			}
-			if err != nil {
-				errS += err.Error() + " "
-				continue
-			}
-
-			// file exists and no errors encountered
-			fields["exists"] = int64(1)
-			fields["size_bytes"] = fileInfo.Size()
 
 			if f.Md5 {
-				md5, err := getMd5(file)
+				md5, err := getMd5(fileName)
 				if err != nil {
 					errS += err.Error() + " "
 				} else {