# HG changeset patch
# User Matthew Wild <mwild1@gmail.com>
# Date 1593186091 -3600
# Node ID 73b8aaf5577599b9c310604f5bef0378307921da
# Parent  5691b9773c5b96769916cf14697a5a2881960b56
util.dbuffer: dynamic string buffer

Similar to util.ringbuffer (and shares almost identical API). Differences:

- size limit is optional and dynamic
- does not allocate a fixed buffer of max_size bytes
- focus on simply storing references to existing string objects where possible,
  avoiding unnecessary allocations
- references are still stored in a ring buffer to enable use as a fast FIFO

Optional second parameter to new() provides the number of ring buffer segments. On
Lua 5.2 on my laptop, a segment is ~19 bytes. If the ring buffer fills up, the next
write will compact all strings into a single item.

diff -r 5691b9773c5b -r 73b8aaf55775 util/queue.lua
--- a/util/queue.lua	Mon Jun 15 14:16:34 2020 +0100
+++ b/util/queue.lua	Fri Jun 26 16:41:31 2020 +0100
@@ -51,6 +51,13 @@
 			end
 			return t[tail];
 		end;
+		replace = function (self, data)
+			if items == 0 then
+				return self:push(data);
+			end
+			t[tail] = data;
+			return true;
+		end;
 		items = function (self)
 			--luacheck: ignore 431/t
 			return function (t, pos)