util.dbuffer: Add efficient shortcuts for discard() in certain cases
If the buffer is already empty, nothing to do. If we're throwing away the
whole buffer, we can just empty it and avoid read_chunk() (which in turn
may collapse()). These shortcuts are much more efficient.
describe("util.smqueue", function()
local smqueue
setup(function() smqueue = require "util.smqueue"; end)
describe("#new()", function()
it("should work", function()
local q = smqueue.new(10);
assert.truthy(q);
end)
end)
describe("#push()", function()
it("should allow pushing many items", function()
local q = smqueue.new(10);
for i = 1, 20 do q:push(i); end
assert.equal(20, q:count_unacked());
end)
end)
describe("#resumable()", function()
it("returns true while the queue is small", function()
local q = smqueue.new(10);
for i = 1, 10 do q:push(i); end
assert.truthy(q:resumable());
q:push(11);
assert.falsy(q:resumable());
end)
end)
describe("#ack", function()
it("allows removing items", function()
local q = smqueue.new(10);
for i = 1, 10 do q:push(i); end
assert.same({ 1; 2; 3 }, q:ack(3));
assert.same({ 4; 5; 6 }, q:ack(6));
assert.falsy(q:ack(3), "can't go backwards")
assert.falsy(q:ack(100), "can't ack too many")
for i = 11, 20 do q:push(i); end
assert.same({ 11; 12 }, q:ack(12), "items are dropped");
end)
end)
describe("#resume", function()
it("iterates over current items", function()
local q = smqueue.new(10);
for i = 1, 12 do q:push(i); end
assert.same({ 3; 4; 5; 6 }, q:ack(6));
assert.truthy(q:resumable());
local resume = {}
for _, i in q:resume() do resume[i] = true end
assert.same({ [7] = true; [8] = true; [9] = true; [10] = true; [11] = true; [12] = true }, resume);
end)
end)
describe("#table", function ()
it("produces a compat layer", function ()
local q = smqueue.new(10);
for i = 1,10 do q:push(i); end
do
local t = q:table();
assert.same({ 1; 2; 3; 4; 5; 6; 7; 8; 9; 10 }, t);
end
do
for i = 11,20 do q:push(i); end
local t = q:table();
assert.same({ 11; 12; 13; 14; 15; 16; 17; 18; 19; 20 }, t);
end
do
q:ack(15);
local t = q:table();
assert.same({ 16; 17; 18; 19; 20 }, t);
end
do
q:ack(20);
local t = q:table();
assert.same({}, t);
end
end)
end)
end);