From 3e3719dda1beae705ba7353e97de0cce604180a2 Mon Sep 17 00:00:00 2001
From: GeorgyKirichenko <kirichenkoga@gmail.com>
Date: Wed, 3 Feb 2016 15:40:23 +0300
Subject: [PATCH] Randomize snapshot start time. Fixed #732
---
src/box/lua/snapshot_daemon.lua | 45 +++++++++++--------------------
test/box/snapshot_daemon.result | 43 +++++++++++++++++++++++++++++
test/box/snapshot_daemon.test.lua | 23 ++++++++++++++++
3 files changed, 81 insertions(+), 30 deletions(-)
diff --git a/src/box/lua/snapshot_daemon.lua b/src/box/lua/snapshot_daemon.lua
index 81b7bc6c4f..1db09b81d3 100644
--- a/src/box/lua/snapshot_daemon.lua
+++ b/src/box/lua/snapshot_daemon.lua
@@ -6,11 +6,14 @@ do
local fio = require 'fio'
local yaml = require 'yaml'
local errno = require 'errno'
+ local digest = require 'digest'
+ local pickle = require 'pickle'
local PREFIX = 'snapshot_daemon'
local daemon = {
snapshot_period = 0;
+ snapshot_period_bias = 0;
snapshot_count = 6;
}
@@ -145,7 +148,7 @@ do
local function next_snap_interval(self)
-
+
-- don't do anything in hot_standby mode
if box.info.status ~= 'running' or
self.snapshot_period == nil or
@@ -153,34 +156,8 @@ do
return nil
end
- local interval = self.snapshot_period / 10
-
- local time = fiber.time()
- local snaps = fio.glob(fio.pathjoin(box.cfg.snap_dir, '*.snap'))
- if snaps == nil or #snaps == 0 then
- return interval
- end
-
- local last_snap = snaps[ #snaps ]
- local stat = fio.stat(last_snap)
-
- if stat == nil then
- return interval
- end
-
-
- -- there is no activity in xlogs
- if self.snapshot_period * 2 + stat.mtime < time then
- return interval
- end
-
- local time_left = self.snapshot_period + stat.mtime - time
- if time_left > 0 then
- return time_left
- end
-
- return interval
-
+ return self.snapshot_period -
+ (fiber.time() + self.snapshot_period_bias) % self.snapshot_period
end
local function daemon_fiber(self)
@@ -221,6 +198,12 @@ do
__index = {
set_snapshot_period = function()
daemon.snapshot_period = box.cfg.snapshot_period
+ if daemon.snapshot_period > 0 then
+ local rnd = pickle.unpack('i', digest.urandom(4))
+ daemon.snapshot_period_bias = rnd % daemon.snapshot_period
+ else
+ daemon.snapshot_period_bias = 0
+ end
reload(daemon)
return
end,
@@ -232,7 +215,9 @@ do
end
daemon.snapshot_count = box.cfg.snapshot_count
reload(daemon)
- end
+ end,
+
+ next_snap_interval = next_snap_interval
}
})
diff --git a/test/box/snapshot_daemon.result b/test/box/snapshot_daemon.result
index 169e7c2fb0..0cf8bedb7e 100644
--- a/test/box/snapshot_daemon.result
+++ b/test/box/snapshot_daemon.result
@@ -132,3 +132,46 @@ daemon.snapshot_count = 20
box.cfg{ snapshot_count = 0 }
---
...
+-- first start daemon
+box.cfg{ snapshot_count = 2, snapshot_period = 3600}
+---
+...
+period_bias = daemon.snapshot_period_bias
+---
+...
+next_snap_interval = daemon.next_snap_interval(daemon)
+---
+...
+test_snap_interval = 3600 - (fiber.time() + period_bias) % 3600
+---
+...
+(next_snap_interval - test_snap_interval + 3600) % 3600 < 2
+---
+- true
+...
+biases = {}
+---
+...
+max_equals = 0
+---
+...
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+for i = 1, 20 do
+ box.cfg{ snapshot_period = 0}
+ box.cfg{ snapshot_period = 3600}
+ biases[daemon.snapshot_period_bias] = (biases[daemon.snapshot_period_bias] or 0) + 1
+ if biases[daemon.snapshot_period_bias] > max_equals then
+ max_equals = biases[daemon.snapshot_period_bias]
+ end
+end
+
+test_run:cmd("setopt delimiter ''");
+---
+...
+max_equals < 4
+---
+- true
+...
diff --git a/test/box/snapshot_daemon.test.lua b/test/box/snapshot_daemon.test.lua
index cf98a93d9e..8acaed3877 100644
--- a/test/box/snapshot_daemon.test.lua
+++ b/test/box/snapshot_daemon.test.lua
@@ -72,3 +72,26 @@ daemon.snapshot_count = 20
-- stop daemon
box.cfg{ snapshot_count = 0 }
+
+-- first start daemon
+box.cfg{ snapshot_count = 2, snapshot_period = 3600}
+period_bias = daemon.snapshot_period_bias
+next_snap_interval = daemon.next_snap_interval(daemon)
+test_snap_interval = 3600 - (fiber.time() + period_bias) % 3600
+(next_snap_interval - test_snap_interval + 3600) % 3600 < 2
+
+biases = {}
+max_equals = 0
+test_run:cmd("setopt delimiter ';'")
+
+for i = 1, 20 do
+ box.cfg{ snapshot_period = 0}
+ box.cfg{ snapshot_period = 3600}
+ biases[daemon.snapshot_period_bias] = (biases[daemon.snapshot_period_bias] or 0) + 1
+ if biases[daemon.snapshot_period_bias] > max_equals then
+ max_equals = biases[daemon.snapshot_period_bias]
+ end
+end
+
+test_run:cmd("setopt delimiter ''");
+max_equals < 4
--
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