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authorKim Alvefur <zash@zash.se>2021-12-14 19:58:53 +0100
committerKim Alvefur <zash@zash.se>2021-12-14 19:58:53 +0100
commit93a9ed262065d9966643ad5ae50b58142a1c6823 (patch)
tree0fbcc8578d3aefac8a5021d36a86c5ae2aa78950 /teal-src/util
parentbdce99b7dd4411a8717798874a320bd2fc191b57 (diff)
downloadprosody-93a9ed262065d9966643ad5ae50b58142a1c6823.tar.gz
prosody-93a9ed262065d9966643ad5ae50b58142a1c6823.zip
util.smqueue: Abstract queue with acknowledgements and overflow
Meant to be used in mod_smacks for XEP-0198 Meant to have a larger virtual size than actual number of items stored, on the theory that in most cases, the excess will be acked before needed for a resumption event.
Diffstat (limited to 'teal-src/util')
-rw-r--r--teal-src/util/smqueue.tl107
1 files changed, 107 insertions, 0 deletions
diff --git a/teal-src/util/smqueue.tl b/teal-src/util/smqueue.tl
new file mode 100644
index 00000000..0bbceb8e
--- /dev/null
+++ b/teal-src/util/smqueue.tl
@@ -0,0 +1,107 @@
+local queue = require "util.queue";
+
+local record lib
+ -- T would typically be util.stanza
+ record smqueue<T>
+ _queue : queue.queue<T>
+ _head : integer
+ _tail : integer
+
+ enum ack_errors
+ "tail"
+ "head"
+ "pop"
+ end
+ push : function (smqueue, T)
+ ack : function (smqueue, integer) : { T }, ack_errors
+ resumable : function (smqueue) : boolean
+ type consume_iter = function (smqueue<T>) : T
+ consume : function (smqueue<T>) : consume_iter
+
+ table : function (smqueue<T>) : { T }
+ end
+ new : function <T>(integer) : smqueue<T>
+end
+
+local type smqueue = lib.smqueue;
+
+function smqueue:push(v)
+ self._head = self._head + 1;
+ -- Wraps instead of errors
+ assert(self._queue:push(v));
+end
+
+function smqueue:ack(h : integer) : { any }, smqueue.ack_errors
+ if h < self._tail then
+ return nil, "tail";
+ elseif h > self._head then
+ return nil, "head";
+ end
+ -- TODO optimize? cache table fields
+ local acked = {};
+ self._tail = h;
+ local expect = self._head - self._tail;
+ while expect < self._queue:count() do
+ local v = self._queue:pop();
+ if not v then return nil, "pop"; end
+ table.insert(acked, v);
+ end
+ return acked;
+end
+
+function smqueue:count_unacked() : integer
+ return self._head - self._tail;
+end
+
+function smqueue:count_acked() : integer
+ return self._tail;
+end
+
+function smqueue:resumable() : boolean
+ return self._queue:count() >= (self._head - self._tail);
+end
+
+function smqueue:resume() : queue.queue.iterator, any, integer
+ return self._queue:items();
+end
+
+function smqueue:consume() : queue.queue.consume_iter
+ return self._queue:consume()
+end
+
+-- Compatibility wrapper, meant to look like a plain ol' array
+local record compat_mt
+ _queue : smqueue<any>
+end
+
+function compat_mt:__index(i : integer) : any
+ if i < self._queue._tail then return nil end
+ return self._queue._queue._items[(i + self._queue._tail) % self._queue._queue.size];
+end
+
+function compat_mt:__len() : integer
+ return self._queue:count_unacked()
+end
+
+function smqueue:table() : { any }
+ return setmetatable({ _queue = self }, compat_mt);
+end
+
+local function freeze(q : smqueue<any>) : { string:integer }
+ return { head = q._head, tail = q._tail }
+end
+
+local queue_mt = {
+ --
+ __name = "smqueue";
+ __index = smqueue;
+ __len = smqueue.count_unacked;
+ __freeze = freeze;
+}
+
+function lib.new<T>(size : integer) : queue.queue<T>
+ assert(size>0);
+ return setmetatable({ _head = 0; _tail = 0; _queue = queue.new(size, true) }, queue_mt);
+end
+
+return lib;