lua: add dump lua stack function and extract flb_lua_arraylength

[nokute78]

I need a debug function to add new feature for flb_lua to fix issue 7708.

This patch is to

• add flb_lua_dump_stack
• modify flb_lua_arraylength to be able to pass index of stack
• add flb_lua_absindex

flb_lua_dump_stack is to dump lua stack for debug.

It needs to modify flb_lua_arraylength since the function expects an array should be on the top of the stack.
flb_lua_dump_stack needs to dump an array in the middle of the stack.

This patch also supports flb_lua_absindex.
In some cases, we use negative index to point from a top of the stack. e.g. lua_next(l, -2) of flb_lua_arraylength.
It can cause an error when the top of stack is added/deleted.
flb_lua_absindex is to prevent it since it returns a positive index from the bottom of the stack.

---

Enter [N/A] in the box, if an item is not applicable to your change.

Testing
Before we can approve your change; please submit the following in a comment:

• [N/A] Example configuration file for the change
• Debug log output from testing the change

• Attached Valgrind output that shows no leaks or memory corruption was found

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

• [N/A] Run local packaging test showing all targets (including any new ones) build.
• [N/A] Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

• [N/A] Documentation required for this feature

Backporting

• [N/A] Backport to latest stable release.

Debug/Valgrind output

$ valgrind --leak-check=full bin/flb-it-lua 
==93371== Memcheck, a memory error detector
==93371== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==93371== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==93371== Command: bin/flb-it-lua
==93371== 
Test lua_is_valid_func...                       [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_pushtimetable...                       [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_pushmsgpack...                         [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_pushmpack...                           [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_tomsgpack...                           [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_tompack...                             [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_arraylength...                         [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_arraylength_with_index...              [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
Test lua_arraylength_for_array_contains_nil...  [ OK ]
==93371== Warning: invalid file descriptor -1 in syscall close()
SUCCESS: All unit tests have passed.
==93371== 
==93371== HEAP SUMMARY:
==93371==     in use at exit: 0 bytes in 0 blocks
==93371==   total heap usage: 7,563 allocs, 7,563 frees, 821,606 bytes allocated
==93371== 
==93371== All heap blocks were freed -- no leaks are possible
==93371== 
==93371== For lists of detected and suppressed errors, rerun with: -s
==93371== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

$ valgrind --leak-check=full bin/flb-rt-filter_lua 
==93377== Memcheck, a memory error detector
==93377== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==93377== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==93377== Command: bin/flb-rt-filter_lua
==93377== 
Test hello_world...                             [2023/08/13 10:24:59] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:24:59] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:24:59] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:24:59] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:24:59] [ info] [input:dummy:dummy.0] initializing
[2023/08/13 10:24:59] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
[2023/08/13 10:24:59] [ info] [output:stdout:stdout.0] worker #0 started
[2023/08/13 10:24:59] [ info] [sp] stream processor started
[2023/08/13 10:24:59] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:24:59] [ info] [input] pausing dummy.0
[2023/08/13 10:24:59] [ info] [engine] service has stopped (0 pending tasks)
[2023/08/13 10:24:59] [ info] [input] pausing dummy.0
[2023/08/13 10:24:59] [ info] [output:stdout:stdout.0] thread worker #0 stopping...
[2023/08/13 10:24:59] [ info] [output:stdout:stdout.0] thread worker #0 stopped
[ OK ]
Test append_tag...                              [2023/08/13 10:25:00] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:00] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:00] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:00] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:00] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:00] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:00] [ info] [sp] stream processor started
[2023/08/13 10:25:00] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:01] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
Test type_int_key...                            [2023/08/13 10:25:01] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:01] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:01] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:01] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:01] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:01] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:01] [ info] [sp] stream processor started
[2023/08/13 10:25:02] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:03] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
Test type_int_key_multi...                      [2023/08/13 10:25:03] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:03] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:03] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:03] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:03] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:03] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:03] [ info] [sp] stream processor started
[2023/08/13 10:25:04] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:05] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
Test type_array_key...                          [2023/08/13 10:25:05] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:05] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:05] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:05] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:05] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:05] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:05] [ info] [sp] stream processor started
[2023/08/13 10:25:06] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:07] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
Test array_contains_null...                     [2023/08/13 10:25:07] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:07] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:07] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:07] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:07] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:07] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:07] [ info] [sp] stream processor started
[2023/08/13 10:25:08] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:09] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
Test drop_all_records...                        [2023/08/13 10:25:09] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:09] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:09] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:09] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:09] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:09] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:09] [ info] [sp] stream processor started
[2023/08/13 10:25:11] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:11] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
Test split_record...                            [2023/08/13 10:25:11] [ info] [fluent bit] version=2.1.9, commit=7c46a40e17, pid=93377
[2023/08/13 10:25:11] [ info] [storage] ver=1.2.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/08/13 10:25:11] [ info] [cmetrics] version=0.6.3
[2023/08/13 10:25:11] [ info] [ctraces ] version=0.3.1
[2023/08/13 10:25:11] [ info] [input:lib:lib.0] initializing
[2023/08/13 10:25:11] [ info] [input:lib:lib.0] storage_strategy='memory' (memory only)
[2023/08/13 10:25:11] [ info] [sp] stream processor started
[2023/08/13 10:25:13] [ warn] [timeout] elapsed_time: 2005
[2023/08/13 10:25:13] [ warn] [engine] service will shutdown in max 1 seconds
[2023/08/13 10:25:14] [ info] [engine] service has stopped (0 pending tasks)
[ OK ]
SUCCESS: All unit tests have passed.
==93377== 
==93377== HEAP SUMMARY:
==93377==     in use at exit: 0 bytes in 0 blocks
==93377==   total heap usage: 12,532 allocs, 12,532 frees, 5,934,382 bytes allocated
==93377== 
==93377== All heap blocks were freed -- no leaks are possible
==93377== 
==93377== For lists of detected and suppressed errors, rerun with: -s
==93377== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

---

Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[edsiper]

@tarruda can you take a look at this pls ?

[tarruda]

LGTM

[edsiper]

thank you!