From 0c41e9305c227126874c44ff96c0d57091a21dff Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Sat, 8 Jul 2023 22:15:56 +0100
Subject: [PATCH] extract service output watcher to fennel module

---
 examples/acquire-delegated-prefix.fnl | 38 +++++----------------------
 pkgs/anoia/default.nix                |  4 ++-
 pkgs/anoia/svc.fnl                    | 31 ++++++++++++++++++++++
 3 files changed, 40 insertions(+), 33 deletions(-)
 create mode 100644 pkgs/anoia/svc.fnl

diff --git a/examples/acquire-delegated-prefix.fnl b/examples/acquire-delegated-prefix.fnl
index b66e0ef..4d3175c 100644
--- a/examples/acquire-delegated-prefix.fnl
+++ b/examples/acquire-delegated-prefix.fnl
@@ -1,5 +1,5 @@
-(local inotify (require :inotify))
 (local { : merge : split : file-exists? : system } (require :anoia))
+(local svc (require :anoia.svc))
 
 (fn parse-prefix [str]
   (fn parse-extra [s]
@@ -17,32 +17,6 @@
 ;;(parse-prefix "2001:8b0:de3a:40dc::/64,7198,7198")
 ;;(parse-prefix "2001:8b0:de3a:1001::/64,7198,7188,excluded=1/2,thi=10")
 
-(fn read-line [name]
-  (with-open [f (assert (io.open name :r) (.. "can't open file " name))]
-    (f:read "*l")))
-
-(fn watch-fsevents [directory-name]
-  (let [handle (inotify.init)]
-    (handle:addwatch directory-name
-                     inotify.IN_CREATE
-                     inotify.IN_MOVE
-                     inotify.IN_DELETE
-                     inotify.IN_DELETE_SELF
-                     inotify.IN_MOVED_FROM
-                     inotify.IN_MOVED_TO
-                     inotify.IN_CLOSE_WRITE)
-    handle))
-
-(fn watch-directory [pathname]
-  (let [watcher (watch-fsevents pathname)]
-    {
-     :has-file? (fn [_ filename] (file-exists? (.. pathname "/" filename)))
-     :wait-events (fn [] (watcher:read))
-     :ready? (fn [self]
-               (and (self:has-file? "state") (not (self:has-file? ".lock"))))
-     :read-line (fn [_ filename] (read-line (.. pathname "/" filename)))
-     :close #(watcher:close)
-     }))
 
 (local bound-states
        { :bound true
@@ -68,12 +42,12 @@
     (values added deleted)))
 
 (let [[state-directory lan-device] arg
-      dir (watch-directory state-directory)]
+      dir (svc.open state-directory)]
   (var prefixes [])
   (while true
-    (while (not (dir:ready?)) (dir:wait-events))
-    (if (. bound-states (dir:read-line "state"))
-        (let [new-prefixes (split " " (dir:read-line "/prefixes"))
+    (while (not (dir:ready?)) (dir:wait))
+    (if (. bound-states (dir:output "state"))
+        (let [new-prefixes (split " " (dir:output "/prefixes"))
               (added deleted) (changes prefixes new-prefixes)]
           (each [_ p (ipairs added)]
             (system
@@ -82,4 +56,4 @@
             (system
              (.. "ip address del " p.prefix "::1/" p.len " dev " lan-device)))
     	  (set prefixes new-prefixes)))
-    (dir:wait-events)))
+    (dir:wait)))
diff --git a/pkgs/anoia/default.nix b/pkgs/anoia/default.nix
index 1f52732..5af98ae 100644
--- a/pkgs/anoia/default.nix
+++ b/pkgs/anoia/default.nix
@@ -10,7 +10,9 @@ in stdenv.mkDerivation {
   src = ./.;
   nativeBuildInputs = [ fennel ];
   buildPhase = ''
-    fennel --compile init.fnl > init.lua
+    for f in *.fnl ; do
+      fennel --compile $f > `basename $f .fnl`.lua
+    done
   '';
   installPhase = ''
     mkdir -p "$out/share/lua/${lua.luaversion}/${pname}"
diff --git a/pkgs/anoia/svc.fnl b/pkgs/anoia/svc.fnl
new file mode 100644
index 0000000..002583c
--- /dev/null
+++ b/pkgs/anoia/svc.fnl
@@ -0,0 +1,31 @@
+(local inotify (require :inotify))
+(local { : file-exists? } (require :anoia))
+
+(fn read-line [name]
+  (with-open [f (assert (io.open name :r) (.. "can't open file " name))]
+    (f:read "*l")))
+
+(fn watch-fsevents [directory-name]
+  (let [handle (inotify.init)]
+    (handle:addwatch directory-name
+                     inotify.IN_CREATE
+                     inotify.IN_MOVE
+                     inotify.IN_DELETE
+                     inotify.IN_DELETE_SELF
+                     inotify.IN_MOVED_FROM
+                     inotify.IN_MOVED_TO
+                     inotify.IN_CLOSE_WRITE)
+    handle))
+
+(fn open [directory]
+  (let [watcher (watch-fsevents directory)
+        has-file? (fn [filename] (file-exists? (.. directory "/" filename)))]
+    {
+     :wait (fn [] (watcher:read))
+     :ready? (fn [self]
+               (and (has-file? "state") (not (has-file? ".lock"))))
+     :output (fn [_ filename] (read-line (.. directory "/" filename)))
+     :close #(watcher:close)
+     }))
+
+{ : open }