A simple example is in the test-run source tree
(`test/test-luatest/smoke_check_test.lua`).

https://github.com/tarantool/test-run/issues/304
https://github.com/tarantool/test-run/pull/310

The idea of these changes is to run testing workflows on self-hosted
ubuntu-20.04 machines instead of GitHub ubuntu-20.04 runners. It is
planned to use GitHub ubuntu-20.04 runners only for integration testing
of tarantool with a module/connector where ephemeral environments will
allow us avoiding various cleanup pains on self-hosted runners like

    - if: always()
      run: sudo apt-get -y purge 'tarantool*'

or

    - if: always()
      run: rm -rf .rocks

or

    - if: always()
      run: rm -rf pytest-venv

Also, switch workflows running on GitHub ubuntu-18.04 runners to
self-hosted ubuntu-20.04 machines.

Bump debian/compat to 10 since 9 is deprecated. Bump minimal required
debhelper to 10 (except for Ubuntu Trusty and Xenial) since it is the
recommended practice for compatibility level setup.

Closes #6393

The maximal unix socket file length is 108 symbols on Linux, so
we should decrease file name to fit in this size.

The session can be closed while kharon is travelling between tx and
iproto. If this happens, kharon shouldn't go back to iproto when it
returns to tx, even if there are pending pushes, because the connection
is going to be freed soon.

Thanks to @Gerold103 for the simple fix.

Closes #6520

This patch removes the DECIMAL truncation in LIMIT and OFFSET, because
according to the implicit casting rules, DECIMAL with digits after the
decimal point cannot be implicitly cast to INTEGER.

Closes #6485

This patch fixes an assertion when casting DECIMAL value less than 0 and
greater than -1 to INTEGER.

Part of #6485

In case the DECIMAL value is implicitly cast to INTEGER during a search
using an index, it was possible that DECIMAL would be truncated, which
is not correct according to the implicit cast rules. This patch removes
this truncation.

Part of #6485

In case user enters invalid listen address, tarantool closes previous listen
socket, but bind on invalid address fails also, so tarantool becames blind -
no listening socket at all. This patch fixed this behaviour, now tarantool
still listen old listen address.

Closes #6092

There was access to previously freed memory in case when `cbus_call`
is interrupted: `cbus_call_msg` in iproto allocates on stack, and if
`cbus_call` failed due to fiber cancelation or wake up, `cbus_call_msg`
memory is released. But function called through cbus is still work in
iproto thread and there will be an attempt to access this memory when
this function in iproto thread finished it's work. This patch rework
this behaviour, now before `cbus_call` we reset FIBER_IS_CANCELLABLE
flag, to prevent fiber cancellation or it's wake up.

Closes #6480

For self-host runners, where the workspace with sources is saving
between different workflow runs, it is needed to be sure that all file
permissions are correct for running user to be sure that later call to
sources checkout action by the same user won't fail on sources cleanup.

Follows up tarantool/tarantool-qa#102

This patch extends the 'integration.yml' workflow and adds a new
workflow call for running tests to verify integration between tarantool
and the cartridge module.

Part of #5265
Part of #6056
Closes #6512

Imagine the following situation. One pushed a commit to the master
branch, the 'integration.yml' workflow is triggered and starts to work.
The first step of this workflow is to build tarantool from the pushed
commit. Sometimes we have to wait for a free runner for some period of
time because our resources are limited. One pushed a commit to the
master branch one more time, but tarantool build for the previous
commit hasn't started yet. When tarantool build from the previous
commit starts, actually tarantool will be built from the last commit
because ${{ github.ref }} is passed to the 'reusable_build.yml'
workflow as an input parameter. So we need to pass ${{ github.sha }}.

Now it is possible to mark test files with tags and run some group of
tests using the `--tags` option.

Usage:

 | ./test-run.py --tags foo
 | ./test-run.py --tags foo,bar app/ app-tap/

Show the list of tags:

 | ./test-run.py --tags
 | ./test-run.py app-tap/ --tags

See syntax and more details in
https://github.com/tarantool/test-run/pull/314

See the task description and possible usages in
https://github.com/tarantool/test-run/issues/22

Promote @Totktonada to be a new maintainer for debian packages.

Closes #6392

Bump tarantool-common dependency to use luarocks 3.
Prior to this patch, it was permitted to have
new tarantool package (version >= 2.2.1) installed with
pre-luarocks 3 tarantool-common package (version << 2.2.1).
It caused rocks install to fail.

Closes #5429

Introduced module for timestamp and interval types support.

Closes #5941

For the purposes of format support in datetime we need to modify
standard strftime() implementation so it will be accepting %f flag
we want to use for displaying of fractional part of seconds.

Used Olson' strftime() implementation, simplified their code and
header file, and adapted to work with our `struct datetime` data
structure.
We store timezone information there, seconds since epoch, and
nanoseconds, thus we modified a way how those have being retrieved
in the original implementation.

We have also added missing `%f` and width modifiers support.

```
tarantool> T:format('%d')
---
- '14'
...

tarantool> T:format('%3d')
---
- 3d
...
tarantool> T:format('%3f')
---
- 371
...
tarantool> T:format()
---
- 2021-09-14T12:10:30.371895+0300
...
tarantool> T:format('%FT%T.%f%z')
---
- 2021-09-14T12:10:30.371895+0300
...
```

Created detailed strftime formats test to cover all of known
format flags.

Part of #5941

Introduce a new builtin Tarantool module `datetime.lua` for timestamp
and interval types support.

New third_party module - c-dt
-----------------------------

* Integrated chansen/c-dt parser as 3rd party module to the
  Tarantool cmake build process;
* We use tarantool/c-dt instead of original chansen/c-dt to
  have an easier cmake build integration, as we have added some
  changes, which provide cmake support, and allow to rename symbols
  if necessary (this symbol renaming is similar to that we see
  with xxhash or icu).

New built-in module `datetime`
------------------------------

* created a new Tarantool built-in module `datetime`, which uses
  `struct datetime` data structure for keeping timestamp values;
* Lua module uses a number of `dt_*` functions from `c-dt` library,
  but they were renamed to `tnt_dt_*` at the moment of exporting
  from executable - to avoid possible name clashes with external
  libraries.

* At the moment we libc `strftime` for formatting of datetime
  values according to flags passed, i.e. `date:format('%FT%T%z')`
  will return something like '1970-01-01T00:00:00+0000', but
  `date:format('%A %d, %B %Y')` will return 'Thursday 01, January 1970'

* if there is no format provided then we use default
  `tnt_datetime_to_string()` function, which converts datetime
  to their default ISO-8601 output format, i.e.
  `tostring(date)` will return string like "1970-01-01T00:00:00Z"

* There are a number of simplified interfaces
  - totable() for exporting table with attributes names as provided
    by `os.date('*t')`
  - set() method provides unified interface to set values using
    the set of attributes as defined above in totable()

Example,

```
local dt = datetime.new {
	nsec      = 123456789,

	sec       = 19,
	min       = 29,
	hour      = 18,

	day       = 20,
	month     = 8,
	year      = 2021,

	tzoffset  = 180
}

local t = dt:totable()
--[[
{
	sec = 19,
	min = 29,
	wday = 6,
	day = 20,
	nsec = 123456789,
	isdst = false,
	yday = 232,
	tzoffset = 180,
	month = 8,
	year = 2021,
	hour = 18
}
--]]

dt:format()   -- 2021-08-21T14:53:34.032Z
dt:format('%Y-%m-%dT%H:%M:%S')   -- 2021-08-21T14:53:34

dt:set {
	usec      = 123456,

	sec       = 19,
	min       = 29,
	hour      = 18,

	day       = 20,
	month     = 8,
	year      = 2021,

	tzoffset  = 180,

}
dt:set {
	timestamp = 1629476485.124,

	tzoffset  = 180,
}

```

Coverage is

File                 Hits Missed Coverage
-----------------------------------------
builtin/datetime.lua 299  23     92.86%
-----------------------------------------
Total                299  23     92.86%

Part of #5941

@TarantoolBot document
Title: Introduced a new `datetime` module for timestamp and interval support

Create `datetime` module for timestamp and interval types support.
It allows to create date and timestamp values using either object interface,
or via parsing of string values conforming to iso-8601 standard.
One may manipulate (modify, subtract or add) timestamp and interval values.

Please refer to https://hackmd.io/@Mons/S1Vfc_axK#Datetime-in-Tarantool
for a more detailed description of module API.

For now, there is no testing for the tarantool project verifying its
integration with different modules and connectors from the ecosystem.
This is a quite huge gap in our CI system that is going to be covered
by these changes.

This patch introduces a couple of new workflow files that are named
'integration.yml' and 'reusable_build.yml'. The main workflow is
'integration.yml' that will run automatically per push to master and
release branches. Also, this workflow can be run manually against a
development branch. The 'reusable_build.yml' workflow is called by the
main workflow and builds needed tarantool packages (at this moment for
Ubuntu Focal Fossa only), then stores them as a build artifact. After
that, the main workflow calls the 'reusable_testing.yml' workflow from
a module project that tarantool is going to verify integration with.
The testing workflow should download the tarantool build artifact and
run tests against it.

The basic scheme describing the verification process is represented
below:

      integration.yml
             |
             |
             v
     reusable_build.yml --> <artifact>
             |                  |
             |                  |
             v                  |
    reusable_testing.yml <------+
             |
             |
             v
          <result>

For now, we start only with the vshard module. In the future, we are
going to extend the module list incrementally.

Part of #5265
Part of #6056
Closes #4972

Fixes incorrect handling of variable number of arguments in box.func:call().

Closes #6405

Reasons, in short:

* It reaches end of the standard support.
* It looks barely usable with old ca-certificates due to Let's Encrypt
  certificate expire problem.
* It has problems that block updating compat level for our *.deb
  packages.

All details and links can be found in the linked issue.

Fixes #6502

Copyright year in manual page is outdated: update copyright year to
2021.

Closes #5309

There was a bug that led to dirty read after space alter. For the
simplicity sake imagine following setup:

-- space 's' is empty
tx1:begin()
tx1('s:replace{2}')
s:alter({format = format})
s:select{}

Last select returns tuple {2}, however transaction tx1 hasn't been
committed. This happens due to the fact that during alter operation we
create new space, swap all unchanged parts of old space and then delete
old space. During removal of old space we also clean-up all stories
related to it. In turn story destruction may make dirty tuple clean in
case it remains in the index. In the previous implementation there was
no removal of uncommitted tuples from corresponding indexes. So let's
rollback all changes happened to the space right in time of alter. It is
legal since DDL operation anyway aborts ALL other transactions.

Closes #6318
Closes #6263

Since all decoding functions except xrow_decode_header() decode a packet
body, let's pass an xrow_header object to xrow_on_decode_error() instead
of raw pointers to msgpack data. This will simplify packet body decoding
functions a bit while in xrow_decode_header() we can use dump_row_hex()
directly without hurting readability.

While we are at it, make dump_row_hex() static, because it's not used
outside its compilation unit.

xrow_header_has_key() isn't used anywhere.

The purpose of iproto_dml_body_has_key() is unclear - we use it to skip
unknown DML keys, but we would skip them anyway in the switch-case down
the code path, like we do while decoding other requests. The only useful
thing it does is implicitly checks that the key has type MP_UINT, but we
can do that explicitly instead.

xrow_header_decode() checks that the packet body is a valid msgpack and
there's no outstanding data beyond the packet end so we don't need to
redo this checks while decoding the body (e.g. in xrow_decode_dml()).

Prior to this patch, an assertion was thrown if a tuple with an invalid
id was inserted into the _priv system space. This bug appeared only in
the debug build.

Closes #6295

Closes #4909

Fixed error in implementation of `ev_io_closing`: this function
is called to do same work as `fd_kill` and should call it after
checking fd (in `coio_close` we pass invalid event value, that
leads to assertion in new libev version).

Implement ability to pass timeout to 'fiber:join' function.
If timeout expired, join fails with 'timed out' error.

Closes #6203

@TarantoolBot document
Title: ability to set timeout for 'fiber:join' function was implemented
Implement ability to pass timeout to 'fiber:join' function.
If timeout expired, join fails with 'timed out' error.

Add new  metrics `REQUESTS_IN_PROGRESS` and `REQUESTS_IN_STREAM_QUEUE`
to `box.stat.net`, which contain detailed statistics for iproto requests.
These metrics contains same counters as other metrics in `box.stat.net`:
current, rps and total.

Part of #6293

@TarantoolBot document
Title: detailed iproto requests statistics was implemented
Add new  metrics `REQUESTS_IN_PROGRESS` and `REQUESTS_IN_STREAM_QUEUE`
to `box.stat.net`, which contain detailed statistics for iproto requests.
These metrics contains same counters as other metrics in `box.stat.net`:
current, rps and total.
```
-- statistics for requests currently being processed in tx thread.
REQUESTS_IN_PROGRESS:
current: -- count of requests currently being processed in the tx thread
rps: -- count of requests processed by the tx thread per second
total: -- total count of requests processed by tx thread

-- statistics for requests placed in queues of streams.
REQUESTS_IN_STREAM_QUEUE:
current: -- count of requests currently waiting in queues of streams
rps: -- count of requests placed in streams queues per second
total: -- total count of requests, which was placed in queues of streams
          for all time
```

In next patch new rmean for iproto thread statistic, that collected
in tx thread will be implemented. We need rename IPROTO_LAST constant
to make next patch more clear.

There was several different function to get iproto statistic,
one function for one metric. Since we wan't to add some new
metrics it will be better to implement one function for getting
all iproto statistic not add several new functions.

Currently first element in queue of pending requests in
stream is a request which was pushed to tx thread for
processing. In this patch special pointer to this request
(stream->current) was implemented and queue of pending
requests now really contains only pending requests.

OSX workflows use brew for install openssl.
There was a new release of openssl@3.0 and
homebrew updated the openssl formula.

Close #6468

It never returns NULL anymore, because it uses xmalloc for memory
allocations.

It never returns NULL anymore, because it uses xmalloc for memory
allocations.

An mhash is used for allocating system objects. Failing to grow it is
likely to render the Tarantool instance unusuable so better fail early.

Checks of mh(new) and mh(put) return value will be removed in follow-up
patches.