[Tarantool-patches] [PATCH luajit] Always close profiler output file.

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

From: Mike Pall <mike>

Reported by Guilherme Batalheiro.

(cherry picked from commit fca66335d131669cf017420af6963a7565babb58)

Before the patch, a function `prof_finish` wrote a string
`No samples collected` to profiler output file and then exits.
Due to early exit, output file handle stay opened. This patch
fixes condition and file handle is closed even a number of samples
is equal to 0.

Sergey Bronnikov:
* added the description and the test for the problem

Part of tarantool/tarantool#11055
---
Branch: https://github.com/tarantool/luajit/tree/ligurio/gh-xxxx-close-file-profiler

Related issues:
- https://github.com/luajIT/luajIT/issues/1304
- https://github.com/tarantool/tarantool/issues/11055

 src/jit/p.lua                                 |  4 +--
 ...close-profile-dump-with-0-samples.test.lua | 30 +++++++++++++++++++
 .../script.lua                                | 14 +++++++++
 test/tarantool-tests/utils/tools.lua          |  4 +++
 4 files changed, 49 insertions(+), 3 deletions(-)
 create mode 100644 test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua
 create mode 100644 test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua

diff --git a/src/jit/p.lua b/src/jit/p.lua
index 4569d69e..89b49584 100644
--- a/src/jit/p.lua
+++ b/src/jit/p.lua
@@ -228,9 +228,7 @@ local function prof_finish()
     local samples = prof_samples
     if samples == 0 then
       if prof_raw ~= true then out:write("[No samples collected]\n") end
-      return
-    end
-    if prof_ann then
+    elseif prof_ann then
       prof_annotate(prof_count1, samples)
     else
       prof_top(prof_count1, prof_count2, samples, "")
diff --git a/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua
new file mode 100644
index 00000000..b50b5fce
--- /dev/null
+++ b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples.test.lua
@@ -0,0 +1,30 @@
+local tap = require('tap')
+local test = tap.test('lj-1304-close-profile-dump-with-0-samples'):skipcond({
+  ['Test requires /proc filesystem'] = jit.os == 'OSX',
+})
+local utils = require('utils')
+
+test:plan(1)
+
+-- Test file to demonstrate LuaJIT incorrect behaviour with missed
+-- close a file handle for profile output file.
+-- See also: https://github.com/luajIT/luajIT/issues/1304
+
+local p_filename = '/tmp/profile'
+
+-- <makecmd> runs %testname%/script.lua by <LUAJIT_TEST_BINARY>
+-- with the given environment, launch options and CLI arguments.
+local script = utils.exec.makecmd(arg)
+-- Execute a Lua script with start and stop LuaJIT profiler,
+-- it is expected no samples found by profiler. The script's
+-- output is suppressed, it is not interested.
+local _ = script(p_filename)
+
+local p_content = io.open(p_filename):read('a*')
+test:is(utils.tools.trim(p_content), '[No samples collected]',
+        'profile dump has no samples')
+
+-- Teardown.
+os.remove(p_filename)
+
+test:done(true)
diff --git a/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua
new file mode 100644
index 00000000..77335a08
--- /dev/null
+++ b/test/tarantool-tests/lj-1304-close-profile-dump-with-0-samples/script.lua
@@ -0,0 +1,14 @@
+local p_options = 'ri1'
+local p_filename = assert(arg[1], 'filename argument is missing')
+
+require('jit.p').start(p_options, p_filename)
+
+-- No code to generate profiling samples.
+
+-- Stop profiler to execute `jit/p.lua:prof_fmt()`. With zero
+-- samples it triggers early return without closing the file.
+require('jit.p').stop()
+
+-- Make sure LuaJIT profiler is close a file handle.
+local ls_output = io.popen('ls -l /proc/$$/fd'):read('a*')
+assert(ls_output:find(p_filename) == nil, 'file is open')
diff --git a/test/tarantool-tests/utils/tools.lua b/test/tarantool-tests/utils/tools.lua
index 33fcae78..9cb65daf 100644
--- a/test/tarantool-tests/utils/tools.lua
+++ b/test/tarantool-tests/utils/tools.lua
@@ -21,4 +21,8 @@ function M.read_file(path)
   return content
 end
 
+function M.trim(str)
+  return (str:gsub('^%s*(.-)%s*$', '%1'))
+end
+
 return M
-- 
2.34.1