From b8abeed6c7bddb9d9770f3be93dc41400354783b Mon Sep 17 00:00:00 2001
From: Simon Ruderich <simon@ruderich.org>
Date: Thu, 13 Jun 2019 07:58:04 +0200
Subject: [PATCH] nsscash: write state on each successful run

---
 README   |  4 ++++
 main.go  |  4 +++-
 state.go | 18 ++++--------------
 3 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/README b/README
index 059fe51..510ba33 100644
--- a/README
+++ b/README
@@ -95,6 +95,10 @@ running processes!
 Now configure `nsscash` to run regularly, for example via cron or a systemd
 timer.
 
+To monitor `nsscash` for errors one can use the last modification time of the
+state file (see below). It's written on each successful run and not modified
+if an error occurs.
+
 === CONFIGURATION
 
 Nsscash is configured through a simple configuration file written in TOML. A
diff --git a/main.go b/main.go
index b10f57e..5272740 100644
--- a/main.go
+++ b/main.go
@@ -61,7 +61,9 @@ func main() {
 		if err != nil {
 			log.Fatal(err)
 		}
-		err = WriteStateIfChanged(cfg.StatePath, state)
+		// NOTE: Make sure to call WriteState() only if there were no
+		// errors (see WriteState() and README)
+		err = WriteState(cfg.StatePath, state)
 		if err != nil {
 			log.Fatal(err)
 		}
diff --git a/state.go b/state.go
index b0dec1c..fa8dccd 100644
--- a/state.go
+++ b/state.go
@@ -22,15 +22,11 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"reflect"
 	"time"
 )
 
 type State struct {
 	LastModified map[string]time.Time
-
-	// Copy of LastModified to write the state file only on changes
-	origLastModified map[string]time.Time
 }
 
 func LoadState(path string) (*State, error) {
@@ -54,19 +50,13 @@ func LoadState(path string) (*State, error) {
 		state.LastModified = make(map[string]time.Time)
 	}
 
-	state.origLastModified = make(map[string]time.Time)
-	for k, v := range state.LastModified {
-		state.origLastModified[k] = v
-	}
-
 	return &state, nil
 }
 
-func WriteStateIfChanged(path string, state *State) error {
-	// State hasn't changed, nothing to do
-	if reflect.DeepEqual(state.LastModified, state.origLastModified) {
-		return nil
-	}
+func WriteState(path string, state *State) error {
+	// Update the state file even if nothing has changed to provide a
+	// simple way to check if nsscash ran successfully (the state is only
+	// updated if there were no errors)
 
 	x, err := json.Marshal(state)
 	if err != nil {
-- 
2.43.2