From 7d622695ae19e518fded6aa5fbf001dae4652211 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Sat, 14 Mar 2026 10:13:55 -0400
Subject: back: add qver package to track qid versions

---
 back/qver/update.go | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 back/qver/update.go

(limited to 'back/qver/update.go')

diff --git a/back/qver/update.go b/back/qver/update.go
new file mode 100644
index 0000000..afbe51c
--- /dev/null
+++ b/back/qver/update.go
@@ -0,0 +1,29 @@
+package qver
+
+import (
+	"os"
+	"time"
+)
+
+// An UpdateFunc updates the version and state variables. It is called
+// by Version.Get(). If there is an error, it should return the old
+// version and state along with the error.
+type UpdateFunc func(version uint32, state interface{}) (uint32, interface{}, error)
+
+// UpdateOnFileMod returns a state variable and an UpdateFunc that
+// bumps the version when a file or directory is modified. The return
+// values are to be passed to the Update() option.
+func UpdateOnFileMod(path string) (state interface{}, f UpdateFunc) {
+	return time.Now(), func(ver uint32, state interface{}) (uint32, interface{}, error) {
+		mtime := state.(time.Time)
+		info, err := os.Stat(path)
+		if err != nil {
+			return ver, mtime, err
+		}
+		if info.ModTime().After(mtime) {
+			mtime = info.ModTime()
+			ver++
+		}
+		return ver, mtime, err
+	}
+}
-- 
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