Time the other filters at two lengths as well

The avatar checks held a 40000 byte address to half a second, twenty
times tighter than the readme budget that already failed on a slow
host, and in stub mode nearly all of that time went on the fake digest.
Link-commits and link-trailers had no check on a long input at all. The
readme checks' method moves into the harness so all four share it.

A single timing of each length let a busy host that took the CPU away
during the longer one make a linear pass look quadratic. The lengths
now take turns and the fastest timing of each counts, since a busy host
can slow one timing but rarely all five. A ratio under six ends the
turns at once, so only one near the bound of ten waits for all five.

1 file changed, 5 insertions, 18 deletions

diff --git a/tests/extensions/test-about-render.lua b/tests/extensions/test-about-render.luaindex a08de66..cdba28a 100644--- a/tests/extensions/test-about-render.lua+++ b/tests/extensions/test-about-render.lua@@ -266,25 +266,12 @@ out = render("README.md", "**__*_x_*__**") h.contains("every kind of emphasis nests in the others", out, 	"<p><strong><strong><em><em>x</em></em></strong></strong></p>") --- A hostile readme must cost about four times as much at four times the--- length, as a linear pass does, where a quadratic one costs sixteen times--- as much and holds a request for minutes near the size cap. Timing one--- length against the other cancels out how fast the host is, and each--- render repeats until it is long enough to time.-local function seconds(filename, text)-	local runs, started, out = 0, os.clock(), nil-	repeat-		out = render(filename, text)-		runs = runs + 1-	until os.clock() - started >= 0.02-	return (os.clock() - started) / runs, out-end-+-- A hostile readme that renders in more than linear time holds a request+-- for minutes near the size cap. local function stays_linear(name, filename, make, length)-	local short = seconds(filename, make(length))-	local long, out = seconds(filename, make(4 * length))-	h.check(name, long < 10 * short,-		string.format("%.4f s at length %d, then %.4f s at four times that", short, length, long))+	local out = h.stays_linear(name, function(text)+		return render(filename, text)+	end, make, length) 	h.equals(name .. " and still renders as markup", out:sub(1, 22), "<div class='markdown'>") end 
diff --git a/tests/extensions/test-about-render.lua b/tests/extensions/test-about-render.lua
index a08de66..cdba28a 100644
--- a/tests/extensions/test-about-render.lua
+++ b/tests/extensions/test-about-render.lua
@@ -266,25 +266,12 @@ out = render("README.md", "**__*_x_*__**")
 h.contains("every kind of emphasis nests in the others", out,
 	"<p><strong><strong><em><em>x</em></em></strong></strong></p>")
 
--- A hostile readme must cost about four times as much at four times the
--- length, as a linear pass does, where a quadratic one costs sixteen times
--- as much and holds a request for minutes near the size cap. Timing one
--- length against the other cancels out how fast the host is, and each
--- render repeats until it is long enough to time.
-local function seconds(filename, text)
-	local runs, started, out = 0, os.clock(), nil
-	repeat
-		out = render(filename, text)
-		runs = runs + 1
-	until os.clock() - started >= 0.02
-	return (os.clock() - started) / runs, out
-end
-
+-- A hostile readme that renders in more than linear time holds a request
+-- for minutes near the size cap.
 local function stays_linear(name, filename, make, length)
-	local short = seconds(filename, make(length))
-	local long, out = seconds(filename, make(4 * length))
-	h.check(name, long < 10 * short,
-		string.format("%.4f s at length %d, then %.4f s at four times that", short, length, long))
+	local out = h.stays_linear(name, function(text)
+		return render(filename, text)
+	end, make, length)
 	h.equals(name .. " and still renders as markup", out:sub(1, 22), "<div class='markdown'>")
 end