From 3900683413da08e6d5507fe227254327c862c7fd Mon Sep 17 00:00:00 2001 From: Daniel Barlow Date: Sun, 2 Jul 2023 00:52:18 +0100 Subject: [PATCH] simplify protocol for watchers of service output directories Previously: the service wrote a timestamp and the receiver read and parsed it to see if there was new data Now: the service writes and removes a .lock file to prevent the receiver reading partial data. The receiver is responsible for remembering the *previous* state and only updating if it's changed --- examples/acquire-delegated-prefix.fnl | 131 ++++++++++++++++---------- pkgs/odhcp-script/odhcp6-script.fnl | 3 +- 2 files changed, 83 insertions(+), 51 deletions(-) diff --git a/examples/acquire-delegated-prefix.fnl b/examples/acquire-delegated-prefix.fnl index 09dbaa01..a4e4562c 100644 --- a/examples/acquire-delegated-prefix.fnl +++ b/examples/acquire-delegated-prefix.fnl @@ -1,6 +1,39 @@ - (local inotify (require :inotify)) +(fn merge [table1 table2] + (collect [k v (pairs table2) &into table1] + k v)) + +(fn split [sep string] + (icollect [v (string.gmatch string (.. "([^" sep "]+)"))] + v)) + +(fn parse-prefix [str] + (fn parse-extra [s] + (let [out {}] + (each [name val (string.gmatch s ",(.-)=([^,]+)")] + (tset out name val)) + out)) + (let [(prefix len preferred valid extra) + (string.match str "(.-)::/(%d+),(%d+),(%d+)(.*)$")] + (merge {: prefix : len : preferred : valid} (parse-extra extra)))) + + +;; Format: /,preferred,valid[,excluded=/][,class=] + +;;(parse-prefix "2001:8b0:de3a:40dc::/64,7198,7198") +;;(parse-prefix "2001:8b0:de3a:1001::/64,7198,7188,excluded=1/2,thi=10") + + +(fn file-exists? [name] + (match (io.open name :r) + f (do (f:close) true) + _ false)) + +(fn read-line [name] + (with-open [f (assert (io.open name :r) (.. "can't open file " name))] + (f:read "*l"))) + (fn watch-fsevents [directory-name] (let [handle (inotify.init)] (handle:addwatch directory-name @@ -13,58 +46,56 @@ inotify.IN_CLOSE_WRITE) handle)) +(fn watch-directory [pathname] + (let [watcher (watch-fsevents pathname)] + { + :has-file? (fn [_ filename] (file-exists? (.. pathname "/" filename))) + :wait-events (fn [] (watcher:read)) + :ready? (fn [self] + (and (self:has-file? "state") (not (self:has-file? ".lock")))) + :read-line (fn [_ filename] (read-line (.. pathname "/" filename))) + :close #(watcher:close) + })) -(fn merge [table1 table2] - (collect [k v (pairs table2) &into table1] - k v)) +(local bound-states + { :bound true + :rebound true + :informed true + :updated true + :ra-updated true + }) -(fn parse-extra [s] - (let [out {}] - (each [name val (string.gmatch s ",(.-)=([^,]+)")] - (tset out name val)) - out)) +; (local { : view } (require :fennel)) -(fn parse-prefixes [prefixes] - (icollect [val (string.gmatch prefixes "([^ ]+)")] - (let [(prefix len preferred valid extra) - (string.match val "(.-)::/(%d+),(%d+),(%d+)(.*)$")] - (merge {: prefix : len : preferred : valid} (parse-extra extra)) - ))) +(fn changes [old-prefixes new-prefixes] + (let [added {} + deleted {} + old-set (collect [_ v (ipairs old-prefixes)] (values v true)) + new-set (collect [_ v (ipairs new-prefixes)] (values v true))] + (each [_ prefix (ipairs new-prefixes)] + (if (not (. old-set prefix)) + (table.insert added (parse-prefix prefix)))) + (each [_ prefix (ipairs old-prefixes)] + (if (not (. new-set prefix)) + (table.insert deleted (parse-prefix prefix)))) + (values added deleted))) -;; Format: /,preferred,valid[,excluded=/][,class=] - -;; (parse-prefixes "2001:8b0:de3a:40dc::/64,7198,7198 2001:8b0:de3a:1001::/64,7198,7188,excluded=1/2,thi=10") - - -(fn file-exists? [name] - (match (io.open name :r) - f (do (f:close) true) - _ false)) - - -(fn read-line [name] - (with-open [f (assert (io.open name :r) (.. "can't open file " name))] - (f:read "*l"))) - -(var last-update 0) -(fn event-time [directory] - (if (file-exists? (.. directory "/state")) - (tonumber (read-line (.. directory "/last-update"))) - nil)) - -(fn wait-for-update [directory fsevents] - (while (<= (or (event-time directory) 0) last-update) - (fsevents:read)) - (set last-update (event-time directory)) - true) +;;(fn execute [s] (do (print s) true)) +(fn execute [s] (assert (os.execute s))) (let [[state-directory lan-device] arg - fsevents (watch-fsevents state-directory)] - (while (wait-for-update state-directory fsevents) - (match (read-line (.. state-directory "/state")) - (where (or :bound :rebound :informed :updated :ra-updated)) - (let [[{ : prefix : len : preferred : valid }] - (parse-prefixes (read-line (.. state-directory "/prefixes")))] - (os.execute (.. "ip address add " prefix "::1/" len - " dev " lan-device))) - _ (os.exit 1)))) + dir (watch-directory 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")) + (added deleted) (changes prefixes new-prefixes)] + (each [_ p (ipairs added)] + (execute + (.. "ip address add " p.prefix "::1/" p.len " dev " lan-device))) + (each [_ p (ipairs deleted)] + (execute + (.. "ip address del " p.prefix "::1/" p.len " dev " lan-device))) + (set prefixes new-prefixes))) + (dir:wait-events))) diff --git a/pkgs/odhcp-script/odhcp6-script.fnl b/pkgs/odhcp-script/odhcp6-script.fnl index 2ab8691b..36544dbf 100644 --- a/pkgs/odhcp-script/odhcp6-script.fnl +++ b/pkgs/odhcp-script/odhcp6-script.fnl @@ -56,8 +56,9 @@ "unbound" false "stopped" false _ true)] - (write-value "last-update" (tostring (os.time))) + (write-value ".lock" (tostring (os.time))) (write-value "ifname" ifname) (write-value "state" state) + (os.remove (.. state-directory "/.lock")) (when ready (with-open [fd (io.open "/proc/self/fd/10" :w)] (fd:write "\n"))))