fiber.yield() call removed from quantile

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 - cpu metrics hot reload [#228](https://github.com/tarantool/metrics/issues/228)
 - cartridge metrics role fails to start without http [#225](https://github.com/tarantool/metrics/issues/225)
+- quantile overflow after `fiber.yield()` [#235](https://github.com/tarantool/metrics/issues/235)
 
 ## [0.8.0] - 2021-04-13
 ### Added

metrics/quantile.lua

@@ -1,11 +1,12 @@
-local fiber = require('fiber')
 local ffi = require('ffi')
 
 local quantile = {}
 
-ffi.cdef[[
-	typedef struct {int Delta, Width; double Value; } sample;
-]]
+if not pcall(ffi.typeof, "sample") then
+	ffi.cdef[[
+		typedef struct sample {int Delta, Width; double Value; } sample;
+	]]
+end
 
 local sample_constructor = ffi.typeof('sample')
 
@@ -134,9 +135,6 @@ function stream:merge(samples, len)
 	local i = 1
     local r = 0
     for z = 1, len do
-        if i % 1000 == 0 then
-            fiber.yield()
-		end
 		local sample = samples[z-1]
 		for j = i, s.l_len do
             local c = s.l[j]
@@ -165,9 +163,6 @@ function stream:query(q)
     local p = s.l[0]
 	local r = 0
 	for i = 1, s.l_len do
-        if i % 500 == 0 then
-            fiber.yield()
-        end
         local c = s.l[i]
         if r + c.Width + c.Delta > t then
             return p.Value
@@ -189,9 +184,6 @@ function stream:compress()
 	local r = s.n - x.Width
 
     for i = s.l_len - 1, 1, -1 do
-        if i % 1000 == 0 then
-            fiber.yield()
-		end
 		local c = make_sample(0)
 		sample_copy(c, s.l[i])
 		if c.Width + x.Width + x.Delta <= s.f(s, r) then

test/quantile_test.lua

@@ -1,4 +1,5 @@
 local quantile = require('metrics.quantile')
+local fiber = require('fiber')
 local ffi = require('ffi')
 local t = require('luatest')
 local g = t.group('quantile')
@@ -104,3 +105,21 @@ g.test_package_reload = function()
     local ok, quantile_package = pcall(require, 'metrics.quantile')
     t.assert(ok, quantile_package)
 end
+
+g.test_fiber_yield = function()
+    local q1 = quantile.NewTargeted({[0.5]=0.01, [0.9]=0.01, [0.99]=0.01}, 1000)
+
+    for _=1,10 do
+        fiber.create(function()
+            for _=1,1e2 do
+                t.assert(q1.b_len < q1.__max_samples)
+                quantile.Insert(q1, math.random(1000))
+            end
+        end)
+    end
+
+    for _=1,10 do
+        t.assert(q1.b_len < q1.__max_samples)
+        quantile.Insert(q1, math.random(1))
+    end
+end