[tarantool-patches] [PATCH 1/4] swim: fix a leak when a trigger is installed
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Fri Jun 28 02:25:43 MSK 2019
SWIM wraps user triggers to prepare arguments. The wrapper
function kept a reference to SWIM object, and prevented its
automatic deletion at GC.
The patch makes this reference weak.
Follow up #4250
---
src/lua/swim.lua | 13 ++++++++++---
test/swim/swim.result | 21 +++++++++++++++++++++
test/swim/swim.test.lua | 10 ++++++++++
3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/src/lua/swim.lua b/src/lua/swim.lua
index b6d826ca0..bae6c0da6 100644
--- a/src/lua/swim.lua
+++ b/src/lua/swim.lua
@@ -786,10 +786,17 @@ local swim_member_event_mt = {
-- @return A function to set as a trigger.
--
local function swim_on_member_event_new(s, callback, ctx)
+ -- Do not keep a hard reference to a SWIM instance. Otherwise
+ -- it is a cyclic reference, and both the instance and the
+ -- trigger will never be GC-ed.
+ s = setmetatable({s}, {__mode = 'v'})
return function(member_ptr, event_mask)
- local m = swim_wrap_member(s, member_ptr)
- local event = setmetatable({event_mask}, swim_member_event_mt)
- return callback(m, event, ctx)
+ local s = s[1]
+ if s then
+ local m = swim_wrap_member(s, member_ptr)
+ local event = setmetatable({event_mask}, swim_member_event_mt)
+ return callback(m, event, ctx)
+ end
end
end
diff --git a/test/swim/swim.result b/test/swim/swim.result
index 05a108614..6004971d0 100644
--- a/test/swim/swim.result
+++ b/test/swim/swim.result
@@ -1574,6 +1574,27 @@ s1:delete()
s2:delete()
---
...
+--
+-- Check that Lua triggers don't keep a reference of SWIM instance
+-- preventing its GC.
+--
+s = swim.new({uri = 0, uuid = uuid(1)})
+---
+...
+_ = s:on_member_event(function() end)
+---
+...
+s = setmetatable({s}, {__mode = 'v'})
+---
+...
+collectgarbage('collect')
+---
+- 0
+...
+s
+---
+- []
+...
test_run:cmd("clear filter")
---
- true
diff --git a/test/swim/swim.test.lua b/test/swim/swim.test.lua
index b4e4adafc..f1139087c 100644
--- a/test/swim/swim.test.lua
+++ b/test/swim/swim.test.lua
@@ -535,4 +535,14 @@ s1:cfg({generation = 5})
s1:delete()
s2:delete()
+--
+-- Check that Lua triggers don't keep a reference of SWIM instance
+-- preventing its GC.
+--
+s = swim.new({uri = 0, uuid = uuid(1)})
+_ = s:on_member_event(function() end)
+s = setmetatable({s}, {__mode = 'v'})
+collectgarbage('collect')
+s
+
test_run:cmd("clear filter")
--
2.20.1 (Apple Git-117)
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