From 9aec69aeb699839887d0e7a0d1e7b2f4900e83b0 Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Sun, 28 Aug 2022 17:09:09 +0300
Subject: [PATCH] Cache file existence state

---
 do.go  |  4 ++--
 ood.go | 27 ++++++++++++++++++++++-----
 run.go |  2 +-
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/do.go b/do.go
index fd3bde0..4fbb6c9 100644
--- a/do.go
+++ b/do.go
@@ -34,7 +34,7 @@ const (
 var TopDir string
 
 func existsDo(fdDep *os.File, cwd, pth string) (bool, error) {
-	if _, err := os.Stat(path.Join(cwd, pth)); err == nil {
+	if FileExists(path.Join(cwd, pth)) {
 		return true, nil
 	}
 	return false, ifcreate(fdDep, pth)
@@ -89,7 +89,7 @@ func findDo(fdDep *os.File, cwd, tgt string) (string, int, error) {
 		if dirAbs == TopDir {
 			break
 		}
-		if _, err = os.Stat(path.Join(dirAbs, RedoDir, TopFile)); err == nil {
+		if FileExists(path.Join(dirAbs, RedoDir, TopFile)) {
 			break
 		}
 		if dirAbs == dirAbsPrev {
diff --git a/ood.go b/ood.go
index 7a31573..3ce732f 100644
--- a/ood.go
+++ b/ood.go
@@ -47,9 +47,26 @@ var (
 	FdOODTgts     *os.File
 	FdOODTgtsLock *os.File
 
+	FileExistsCache map[string]bool = make(map[string]bool)
+
 	ErrMissingTarget = errors.New("invalid format of .rec: missing Target")
 )
 
+func FileExists(p string) bool {
+	if exists, known := FileExistsCache[p]; known {
+		return exists
+	}
+	_, err := os.Stat(p)
+	if err == nil {
+		FileExistsCache[p] = true
+		return true
+	}
+	if os.IsNotExist(err) {
+		FileExistsCache[p] = false
+	}
+	return false
+}
+
 type TgtError struct {
 	Tgt string
 	Err error
@@ -80,13 +97,13 @@ func cwdAndTgt(tgt string) (string, string) {
 
 func isSrc(cwd, tgt string) bool {
 	d, f := path.Split(path.Join(cwd, tgt))
-	if _, err := os.Stat(path.Join(d, f)); err != nil {
+	if !FileExists(path.Join(d, f)) {
 		return false
 	}
-	if _, err := os.Stat(path.Join(d, f+".do")); err == nil {
+	if FileExists(path.Join(d, f+".do")) {
 		return false
 	}
-	if _, err := os.Stat(path.Join(d, RedoDir, f+DepSuffix)); err == nil {
+	if FileExists(path.Join(d, RedoDir, f+DepSuffix)) {
 		return false
 	}
 	return true
@@ -127,14 +144,14 @@ func isOOD(cwd, tgtOrig string, level int, seen map[string]struct{}) (bool, erro
 		tracef(CDebug, "ood: %s%s -> already built", indent, tgtOrig)
 		return false, nil
 	}
-	if _, err := os.Stat(path.Join(cwd, tgt)); err != nil && os.IsNotExist(err) {
+	if !FileExists(path.Join(cwd, tgt)) {
 		tracef(CDebug, "ood: %s%s -> non-existent", indent, tgtOrig)
 		return true, nil
 	}
 	ood := false
 
 	for _, dep := range depInfo.ifcreates {
-		if _, err := os.Stat(path.Join(cwd, dep)); err == nil {
+		if FileExists(path.Join(cwd, dep)) {
 			tracef(CDebug, "ood: %s%s -> %s created", indent, tgtOrig, dep)
 			ood = true
 			goto Done
diff --git a/run.go b/run.go
index 5e67c41..985db83 100644
--- a/run.go
+++ b/run.go
@@ -126,7 +126,7 @@ func (e RunError) Error() string {
 }
 
 func mkdirs(pth string) error {
-	if _, err := os.Stat(pth); err == nil {
+	if FileExists(pth) {
 		return nil
 	}
 	return os.MkdirAll(pth, os.FileMode(0777))
-- 
2.44.0