reset mean counter on next zero

Closes #21

nginx-metrix/storage/collector_wrapper_factory.lua

@@ -9,7 +9,7 @@ local key_sep_collector = '¦'
 -- @return string
 ---
 local normalize_string = function(str)
-    return str:gsub(key_sep_namespace, '_'):gsub(key_sep_collector, '_')
+  return str:gsub(key_sep_namespace, '_'):gsub(key_sep_collector, '_')
 end
 
 local wrapper_metatable = {}
@@ -21,38 +21,38 @@ wrapper_metatable.__index = wrapper_metatable
 -- @return string
 ---
 wrapper_metatable.prepare_key = function(self, key)
-    assert(key ~= nil, ('key can not be nil'))
-    if type(key) ~= 'string' then key = tostring(key) end
+  assert(key ~= nil, ('key can not be nil'))
+  if type(key) ~= 'string' then key = tostring(key) end
 
-    key = normalize_string(key)
+  key = normalize_string(key)
 
-    local key_prefix = ''
+  local key_prefix = ''
 
-    if self.collector_name ~= nil then
-        key_prefix = normalize_string(self.collector_name) .. key_sep_collector .. key_prefix
-    end
+  if self.collector_name ~= nil then
+    key_prefix = normalize_string(self.collector_name) .. key_sep_collector .. key_prefix
+  end
 
-    if namespaces.active() ~= nil then
-        key_prefix = normalize_string(namespaces.active()) .. key_sep_namespace .. key_prefix
-    end
+  if namespaces.active() ~= nil then
+    key_prefix = normalize_string(namespaces.active()) .. key_sep_namespace .. key_prefix
+  end
 
-    return key_prefix .. key
+  return key_prefix .. key
 end
 
 ---
 -- @param key string
 -- @return mixed,int
 ---
 wrapper_metatable.get = function(self, key)
-    return storage_dict.get(self:prepare_key(key))
+  return storage_dict.get(self:prepare_key(key))
 end
 
 ---
 -- @param key string
 -- @return mixed,int,bool
 ----
 wrapper_metatable.get_stale = function(self, key)
-    return storage_dict.get_stale(self:prepare_key(key))
+  return storage_dict.get_stale(self:prepare_key(key))
 end
 
 ---
@@ -63,7 +63,7 @@ end
 -- @return mixed
 ---
 wrapper_metatable.set = function(self, key, value, exptime, flags)
-    return storage_dict.set(self:prepare_key(key), value, exptime, flags)
+  return storage_dict.set(self:prepare_key(key), value, exptime, flags)
 end
 
 ---
@@ -74,7 +74,7 @@ end
 -- @return mixed
 ---
 wrapper_metatable.safe_set = function(self, key, value, exptime, flags)
-    return storage_dict.safe_set(self:prepare_key(key), value, exptime, flags)
+  return storage_dict.safe_set(self:prepare_key(key), value, exptime, flags)
 end
 
 ---
@@ -85,7 +85,7 @@ end
 -- @return mixed
 ---
 wrapper_metatable.add = function(self, key, value, exptime, flags)
-    return storage_dict.add(self:prepare_key(key), value, exptime, flags)
+  return storage_dict.add(self:prepare_key(key), value, exptime, flags)
 end
 
 ---
@@ -96,7 +96,7 @@ end
 -- @return mixed
 ---
 wrapper_metatable.safe_add = function(self, key, value, exptime, flags)
-    return storage_dict.safe_add(self:prepare_key(key), value, exptime, flags)
+  return storage_dict.safe_add(self:prepare_key(key), value, exptime, flags)
 end
 
 ---
@@ -107,14 +107,14 @@ end
 -- @return mixed
 ---
 wrapper_metatable.replace = function(self, key, value, exptime, flags)
-    return storage_dict.replace(self:prepare_key(key), value, exptime, flags)
+  return storage_dict.replace(self:prepare_key(key), value, exptime, flags)
 end
 
 ---
 -- @param key string
 --
 wrapper_metatable.delete = function(self, key)
-    storage_dict.delete(self:prepare_key(key))
+  storage_dict.delete(self:prepare_key(key))
 end
 
 ---
@@ -123,7 +123,7 @@ end
 -- @return mixed
 ---
 wrapper_metatable.incr = function(self, key, value)
-    return storage_dict.incr(self:prepare_key(key), value)
+  return storage_dict.incr(self:prepare_key(key), value)
 end
 
 ---
@@ -132,7 +132,7 @@ end
 -- @return mixed
 ---
 wrapper_metatable.safe_incr = function(self, key, value)
-    return storage_dict.safe_incr(self:prepare_key(key), value)
+  return storage_dict.safe_incr(self:prepare_key(key), value)
 end
 
 ---
@@ -141,22 +141,24 @@ end
 -- @return mixed
 ---
 wrapper_metatable.mean_add = function(self, key, value)
-    key = self:prepare_key(key)
-    local prev_value, counter = storage_dict.get(key)
-    value = ((prev_value or 0) * counter + value) / (counter + 1)
-    return storage_dict.set(key, value, nil, counter + 1)
+  key = self:prepare_key(key)
+  local prev_value, counter = storage_dict.get(key)
+  value = ((prev_value or 0) * counter + value) / (counter + 1)
+  return storage_dict.set(key, value, nil, counter + 1)
 end
 
 ---
 -- @param key string
 ---
 wrapper_metatable.mean_flush = function(self, key)
-    key = self:prepare_key(key)
-    local prev_value, counter = storage_dict.get(key)
-    if counter > 0 then
-        counter = 1
-    end
-    storage_dict.set(key, (prev_value or 0), 0, counter)
+  key = self:prepare_key(key)
+  local prev_value, counter = storage_dict.get(key)
+  if counter > 0 then
+    counter = prev_value > 0 and 1 or 0
+  else
+    prev_value = 0
+  end
+  storage_dict.set(key, (prev_value or 0), 0, counter)
 end
 
 ---
@@ -165,32 +167,32 @@ end
 -- @return mixed
 ---
 wrapper_metatable.cyclic_incr = function(self, key, value)
-    return storage_dict.safe_incr(self:prepare_key(key) .. '^^next^^', value)
+  return storage_dict.safe_incr(self:prepare_key(key) .. '^^next^^', value)
 end
 
 ---
 -- @param key string
 ---
 wrapper_metatable.cyclic_flush = function(self, key)
-    key = self:prepare_key(key)
-    local next_key = key .. '^^next^^'
-    local next_value = storage_dict.get(next_key) or 0
-    storage_dict.delete(next_key)
-    storage_dict.set(key, next_value, 0, 0)
+  key = self:prepare_key(key)
+  local next_key = key .. '^^next^^'
+  local next_value = storage_dict.get(next_key) or 0
+  storage_dict.delete(next_key)
+  storage_dict.set(key, next_value, 0, 0)
 end
 
 ---
 -- Factory method
 -- @param collector
 ---
 local create = function(collector)
-    local wrapper = {
-        collector_name = collector.name
-    }
+  local wrapper = {
+    collector_name = collector.name
+  }
 
-    setmetatable(wrapper, wrapper_metatable)
+  setmetatable(wrapper, wrapper_metatable)
 
-    return wrapper
+  return wrapper
 end
 
 --------------------------------------------------------------------------------
@@ -201,9 +203,9 @@ local exports = {}
 exports.create = create
 
 if __TEST__ then
-    exports.__private__ = {
-        wrapper_metatable = wrapper_metatable
-    }
+  exports.__private__ = {
+    wrapper_metatable = wrapper_metatable
+  }
 end
 
 return exports

tests/storage/collector_wrapper_factory_spec.lua

@@ -35,6 +35,7 @@ describe('storage.collector_wrapper_factory', function()
 
   after_each(function()
     namespaces.reset_active()
+    mock.clear(dict_mock)
   end)
 
   it('create', function()
@@ -195,6 +196,18 @@ describe('storage.collector_wrapper_factory', function()
     dict_mock.get:revert()
   end)
 
+  it('wrapper_metatable.mean_flush [existent, zero]', function()
+    local wrapper_metatable = mk_wrapper_metatable_mock('collector-mock')
+
+    stub.new(dict_mock, 'get').on_call_with('collector_mock¦test-key').returns(0, 1)
+
+    wrapper_metatable:mean_flush('test-key')
+    assert.spy(dict_mock.get).was.called_with('collector_mock¦test-key')
+    assert.spy(dict_mock.set).was.called_with('collector_mock¦test-key', 0, 0, 0)
+
+    dict_mock.get:revert()
+  end)
+
   it('wrapper_metatable.cyclic_incr', function()
     local wrapper_metatable = mk_wrapper_metatable_mock('collector-mock')