Extend <ALTER TABLE> statement to drop table constraints by their
names.

Closes #4120

@TarantoolBot document
Title: Drop table constraints in SQL
Now, it is possible to drop table constraints (PRIMARY KEY,
UNIQUE, FOREIGN KEY, CHECK) using
<ALTER TABLE table_name DROP CONSTRAINT constraint_name> statement
by their names.

For example:

tarantool> box.execute([[CREATE TABLE test (
                             a INTEGER PRIMARY KEY,
                             b INTEGER,
                             CONSTRAINT cnstr CHECK (a >= 0)
                        );]])
---
- row_count: 1
...

tarantool> box.execute('ALTER TABLE test DROP CONSTRAINT cnstr;')
---
- row_count: 1
...

The same for all the other constraints.

Remove function box_index_by_name() from parser to avoid selects
during parsing. Add the ability to choose index during VDBE code
compilation which will be used to find the tuple to drop from a
system space.

Needed for #4120

Clarify the error message for better user handling. Add the name
of space where the constraint under dropping wasn't founded.

Part of #4120

When checking wheter rejoin is needed, replica loops through all the
instances in box.cfg.replication, which makes it believe that there is a
master holding files, needed by it, since it accounts itself just like
all other instances.
So make replica skip itself when finding an instance which holds files
needed by it, and determining whether rebootstrap is needed.

We already have a working test for the issue, it missed the issue due to
replica.lua replication settings. Fix replica.lua to optionally include
itself in box.cfg.replication, so that the corresponding test works
correctly.

Closes #4759

We have a mechanism for restoring rows originating from an instance that
suffered a sudden power loss: remote masters resend the isntance's rows
received before a certain point in time, defined by remote master vclock
at the moment of subscribe.
However, this is useful only on initial replication configuraiton, when
an instance has just recovered, so that it can receive what it has
relayed but haven't synced to disk.
In other cases, when an instance is operating normally and master-master
replication is configured, the mechanism described above may lead to
instance re-applying instance's own rows, coming from a master it has just
subscribed to.
To fix the problem do not relay rows coming from a remote instance, if
the instance has already recovered.

Closes #4739

Add a filter for relay to skip rows coming from unwanted instances.
A list of instance ids whose rows replica doesn't want to fetch is encoded
together with SUBSCRIBE request after a freshly introduced flag IPROTO_ID_FILTER.

Filtering rows is needed to prevent an instance from fetching its own
rows from a remote master, which is useful on initial configuration and
harmful on resubscribe.

Prerequisite #4739, #3294

@TarantoolBot document

Title: document new binary protocol key and subscribe request changes

Add key `IPROTO_ID_FILTER = 0x51` to the internals reference.
This is an optional key used in SUBSCRIBE request followed by an array
of ids of instances whose rows won't be relayed to the replica.

SUBSCRIBE request is supplemented with an optional field of the
following structure:
```
+====================+
|      ID_FILTER     |
|   0x51 : ID LIST   |
| MP_INT : MP_ARRRAY |
|                    |
+====================+
```
The field is encoded only when the id list is not empty.

There is an assertion in vclock_follow `lsn > prev_lsn`, which doesn't
fire in release builds, of course. Let's at least warn the user on an
attempt to write a record with a duplicate or otherwise broken lsn, and
not follow such an lsn.

Follow-up #4739

is_orphan status check is needed by applier in order to tell relay
whether to send the instance's own rows back or not.

Prerequisite #4739

Found another problem with the test:

 | /builds/DtQXhC5e/0/tarantool/tarantool/test/unit/popen.c:63:6:
 | error: variable 'rc' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
 |        if (handle == NULL)
 |            ^~~~~~~~~~~~~~

Decided to revert it and fix in background.

This reverts commit 40a51647.

Found another problem with the test:

 | /builds/DtQXhC5e/0/tarantool/tarantool/test/unit/popen.c:63:6:
 | error: variable 'rc' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
 |        if (handle == NULL)
 |            ^~~~~~~~~~~~~~

Decided to revent the test and so revent its disabling.

This reverts commit bceaf05c.

This test is buggy, need to rewrite. Thus to not block other developers
which refer the master branch just disable it.

The test was added in 40a51647 ('test:
unit/popen').

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Alexander Turenko <alexander.turenko@tarantool.org>

Fix for commit f58cb606 ('popen:
introduce a backend engine').

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Alexander Turenko <alexander.turenko@tarantool.org>

Basic tests for popen engine

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

In the patch we introduce popen backend engine which provides
a way to execute external programs and communicate with their
stdin/stdout/stderr streams.

It is possible to run a child process with:

 a) completely closed stdX descriptors
 b) provide /dev/null descriptors to appropritate stdX
 c) pass new transport into a child (currently we use
    pipes for this sake, but may extend to tty/sockets)
 d) inherit stdX from a parent, iow do nothing

On tarantool start we create @popen_pids_map hash which maps
created processes PIDs to popen_handle structure, this structure
keeps everything needed to control and communicate with the children.
The hash will allow us to find a hild process quickly from inside
of a signal handler.

Each handle links into @popen_head list, which is need to be able
to destory children processes on exit procedure (ie when we exit
tarantool and need to cleanup the resources used).

Every new process is born by vfork() call - we can't use fork()
because of at_fork() handlers in libeio which cause deadlocking
in internal mutex usage. Thus the caller waits until vfork()
finishes its work and runs exec (or exit with error).

Because children processes are running without any limitations
they can exit by self or can be killed by some other third side
(say user of a hw node), we need to watch their state which is
done by setting a hook with ev_child_start() helper. This helper
allows us to catch SIGCHLD when a child get exited/signaled
and unregister it from a pool or currently running children.
Note the libev wait() reaps child zomby by self. Another
interesting detail is that libev catches signal in async way
but our SIGCHLD hook is called in sync way before child reap.

This engine provides the following API:
 - popen_init
	to initialize engine
 - popen_free
	to finalize engine and free all reasources
	allocated so far
 - popen_new
	to create a new child process and start it
 - popen_delete
	to release resources occupied and
	terminate a child process
 - popen_stat
	to fetch statistics about a child process
 - popen_command
	to fetch command line string formerly used
	on the popen object creation
 - popen_write_timeout
	to write data into child's stdin with
	timeout
 - popen_read_timeout
	to read data from child's stdout/stderr
	with timeout
 - popen_state
	to fetch state (alive, exited or killed) and
	exit code of a child process
 - popen_state_str
	to get state of a child process in string
	form, for Lua usage mostly
 - popen_send_signal
	to send signal to a child process (for
	example to kill it)

Known issues to fix in next series:

 - environment variables for non-linux systems do not support
   inheritance for now due to lack of testing on my side;

 - for linux base systems we use popen2 system call passing
   O_CLOEXEC flag so that two concurrent popen_create calls
   would not affect each other with pipes inheritance (while
   currently we don't have a case where concurrent calls could
   be done as far as I know, still better to be on a safe side
   from the beginning);

 - there are some files (such as xlog) which tarantool opens
   for own needs without setting O_CLOEXEC flag and it get
   propagated to a children process; for linux based systems
   we use close_inherited_fds helper which walks over opened
   files of a process and close them. But for other targets
   like MachO or FreeBSD this helper just zapped simply because
   I don't have such machines to experimant with; we should
   investigate this moment in more details later once base
   code is merged in;

 - need to consider a case where we will be using piping for
   descriptors (for example we might be writting into stdin
   of a child from another pipe, for this sake we could use
   splice() syscall which gonna be a way faster than copying
   data inside kernel between process). Still the question
   is -- do we really need it? Since we use interanal flags
   in popen handle this should not be a big problem to extend
   this interfaces;

   this particular feature is considered to have a very low
   priority but I left it here just to not forget.

Part-of #4031

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

There is no reason to hide functions. In particular
we will use these helpers in popen code.

Part-of #4031

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

The commit e8009f41 ('box: user.grant
error should be versatile') did not do proper clean-up: it grants
non-default privileges for user 'guest' and does not revoke them at the
end. That caused occasional failures of other tests, all with the same
error saying user 'guest' already had access on universe.

This case should be handled by test-run in a future, see [1].

[1]: https://github.com/tarantool/test-run/issues/156

Follows up #714

After #4736 regression fix (in fact it just reverts the new logic in
small) it is possible again that a fiber's region may hold a memory for
a while, but release it eventually. When the used memory exceeds 128 KiB
threshold, fiber_gc() puts 'garbage' slabs back to slab_cache and
subtracts them from region_used() metric. But until this point those
slabs are accounted in region_used() and so in fiber.info() metrics.

This commit fixes flakiness of test cases of the following kind:

 | fiber.info()[fiber.self().id()].memory.used -- should be zero
 | <...workload...>
 | fiber.info()[fiber.self().id()].memory.used -- should be zero

The problem is that the first `<...>.memory.used` value may be non-zero.
It depends of previous tests that were executed on this tarantool
instance.

The obvious way to solve it would be print differences between
`<...>.memory.used` values before and after a workload instead of
absolute values. This however does not work, because a first slab in a
region can be almost used at the point where a test case starts and a
next slab will be acquired from a slab_cache. This means that the
previous slab will become a 'garbage' and will not be collected until
128 KiB threshold will exceed: the latter `<...>.memory.used` check will
return a bigger value than the former one. However, if the threshold
will be reached during the workload, the latter check may show lesser
value than the former one. In short, the test case would be unstable
after this change.

It is resolved by restarting of a tarantool instance before such test
cases to ensure that there are no 'garbage' slabs in a current fiber's
region.

Note: This works only if a test case reserves only one slab at the
moment: otherwise some memory may be hold after the case (and so a
memory check after a workload will fail). However it seems that our
cases are small enough to don't trigger this situation.

Call of region_free() would be enough, but we have no Lua API for it.

Fixes #4750.

Calling prepare and execute did not update corresponding request statistics
in the box.stat table. This happened because methods that collect stats were
never called where they should have been.

Closes #4756

Error message on granted privileges was not flexible and
did not distinguish between universal or any other privileges
leaving either 'nil' or simply '' at the end.

Closes #714

The bug was in an attempt to update a record in _space_sequence
in-place, to add field path and number. This was not properly
supported by the system space's trigger, and was banned in the
previous patch of this series.

But delete + tuple update + insert work fine. The patch uses them.

To test it the old disabled and heavily outdated
xlog/upgrade.test.lua was replaced with a smaller analogue, which
is supposed to be created separately for each upgrade bug.
According to the new policy of creating test files.

The patch tries to make it easy to add new upgrade tests and
snapshots. A new test should consist of fill.lua script to
populate spaces, snapshot, needed xlogs, and a .test.lua file.
Fill script and binaries should be in the same folder as test file
name, which is located in version folder. Like this:

 xlog/
 |
 + <test_name>.test.lua
 |
 +- upgrade/
    |
    +- <version>/
    |   |
    |   +-<test_name>/
    |     |
    |     +- fill.lua
    |     +- *.snap
    |     +- *.xlog

Version is supposed to say explicitly what a version files in
there have.

Closes #4771

Anyway this does not work for generated sequences. A proper
support of update would complicate the code and won't give
anything useful.

Part of #4771

box.internal.bootstrap() before doing anything turns off system
space triggers, because it is likely to do some hard changes
violating existing rules. And eliminates data from all system
spaces to fill it from the scratch.

Each time when a new space is added, its erasure and turning off
its triggers should have been called explicitly here. As a result
it was not done sometimes, by accident. For example, triggers
were not turned off for _sequence_data, _sequence,
_space_sequence.

Content removal wasn't done for _space_sequence.

The patch makes a generic solution which does not require manual
patching of trigger manipulation and truncation anymore.

The bug was discovered while working on #4771, although it is not
related.

In case if we unable to revert guard page back to
read|write we should never use such slab again.

Initially I thought of just put panic here and
exit but it is too destructive. I think better
print an error and continue. If node admin ignore
this message then one moment at future there won't
be slab left for use and creating new fibers get
prohibited.

In future (hopefully near one) we plan to drop
guard pages to prevent VMA fracturing and use
stack marks instead.

Reviewed-by: Alexander Turenko <alexander.turenko@tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Both madvise and mprotect calls can fail due to various
reasons, mostly because of lack of free memory in the
system.

We log such cases via say_x helpers but this is not enough.
In particular tarantool/memcached relies on diag error to be
set to detect an error condition:

 | expire_fiber = fiber_new(name, memcached_expire_loop);
 | const box_error_t *err = box_error_last();
 | if (err) {
 |	say_error("Can't start the expire fiber");
 |	say_error("%s", box_error_message(err));
 |	return -1;
 | }

Thus lets use diag_set() helper here and instead of macros
use inline functions for better readability.

Fixes #4722

Reported-by: Alexander Turenko <alexander.turenko@tarantool.org>
Reviewed-by: Alexander Turenko <alexander.turenko@tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Providing socket pathname longer than UNIX_PATH_MAX to socket.tcp_server()
will not cause any error, lbox_socket_local_resolve will just truncate the
name according to the limit, causing bad behavior (tarantool will try to
access a socket, which doesn't exist). Thus, let's verify, that pathname
can fit into buffer.

Closes #4634

Our S3 based repositories now reflect packagecloud.io repositories
structure.

It will allow us to migrate from packagecloud.io w/o much complicating
redirection rules on a web server serving download.tarantool.org.

Deploy source packages (*.src.rpm) into separate 'SRPM' repository
like packagecloud.io does.

Changed repository signing key from its subkey to public and moved it
to gitlab-ci environment.

Follows up #3380

To look similar to txn_complete.

Acked-by: Konstantin Osipov <kostja.osipov@gmail.com>
Acked-by: Nikita Pettik <korablev@tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Instead of on_done use on_complete prefix
since done it too general while we're trying
to complete write procedue. Also it is more
consistent with txn_complete name.

Acked-by: Konstantin Osipov <kostja.osipov@gmail.com>
Acked-by: Nikita Pettik <korablev@tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

We're returning int64_t with values 0 or -1 by now,
there is no need for such big return type, plain
integer is enough.

Acked-by: Nikita Pettik <korablev@tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Using void explicitly in functions which take
no arguments allows to optimize code a bit and
don't assume if there might be variable args.

Moreover in commit e070cc4d we dropped arguments
from txn_begin but didn't update vy_scheduler.c.
The compiler didn't complain because it assumed
there are vargs.

Acked-by: Konstantin Osipov <kostja.osipov@gmail.com>
Acked-by: Nikita Pettik <korablev@tarantool.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Found that on 19.02.2020 APT repositories with packages
for Ubuntu 18.10 Cosmic were removed from Ubuntu archive:

 E: The repository 'http://security.ubuntu.com/ubuntu cosmic-security Release' does not have a Release file.
 E: The repository 'http://archive.ubuntu.com/ubuntu cosmic Release' does not have a Release file.
 E: The repository 'http://archive.ubuntu.com/ubuntu cosmic-updates Release' does not have a Release file.
 E: The repository 'http://archive.ubuntu.com/ubuntu cosmic-backports Release' does not have a Release file.

Also found the half a year old message about Ubuntu 18.10
Cosmic EOL:
 https://fridge.ubuntu.com/2019/07/19/ubuntu-18-10-cosmic-cuttlefish-end-of-life-reached-on-july-18-2019/

Removed the Ubuntu 18.10 Cosmic from gitlab-ci and
travis-ci testings.

The server used to crash when any option argument was passed with
a value concatenated to it, like this: '-lvalue', '-evalue'
instead of '-l value' and '-e value'.

However this is a valid way of writing values, and it should not
have crashed regardless of its validity.

The bug was in usage of 'optind' global variable from getopt()
function family. It is not supposed to be used for getting an
option's value. It points to a next argv to parse. Next argv !=
value of current argv, like it was with '-lvalue' and '-evalue'.

For getting a current value there is a variable 'optarg'.

Closes #4775

There was a bug that float +/- float could result into infinity
even if result fits a double. It was fixed by storing double or
float depending on a result value. But it didn't take result field
type into account. That led to a bug when a double field +/- a
value fit the float range, and could be stored as float resulting
into an error at attempt to create a tuple.

Now if a field type is double in the tuple format, it will store
double always, even if it fits the float range.

Follow-up #4701

Currently xrow_update sizeof + store are used to calculate the
result tuple's size, preallocate it as a monolithic memory block,
and save the update tree into it.

Sizeof was expected to return the exact memory size needed for the
tuple. But this is not useful when result size of a field depends
on its format type, and therefore on its position in the tuple.
Because in that case sizeof would need to care about tuple format,
and walk format tree just like store does now. Or it would be
needed to save the found json tree nodes into struct
xrow_update_op during sizeof calculation. All of this would make
sizeof code more complex.

The patch makes it possible for sizeof to return the maximal
needed size. So, for example, a floating point field size now
returns size needed for encoding of a double. And then store can
either encode double or float.

Follow-up #4701

Tuple format now is passed to xrow_update routines. It is going to
be used for two purposes:

- Find field types of the result tuple fields. It will be used to
  decide whether a floating point value should be saved with
  single or double precision;

- In future use the format and tuple offset map to find target
  fields for O(1), without decoding anything. May be especially
  useful for JSON updates of indexed fields.

For the types the format is passed to *_store() functions. Types
can't be calculated earlier, because '!' and '#' operations change
field order. Even if a type would be calculated during operations
appliance for field N, an operation '!' or '#' on field < N would
make this calculation useless.

Follow-up #4701

Before the patch there were the rules:
* float +/- double = double
* double +/- double = double
* float +/- float = float

The rules were applied regardless of values. That led to a problem
when float + float exceeding maximal float value could fit into
double, but was stored as an infinity.

The patch makes so that if a floating point arithmetic operation
result fits into float, it is stored as float. Otherwise as
double. Regardless of initial types.

This alongside saves some memory for cases when doubles can be
stored as floats, and therefore takes 4 less bytes. Although
these cases are rare, because any not integer value stored in a
double may have a long garbage tail in its fraction.

Closes #4701

os.setenv() and os.environ() are Lua API for

    extern char **environ;
    int setenv();

The Open Group standardized access points for environment
variables. But there is no a word about that environ never
changes. Programs can't relay on that. For example, addition of
a new variable may cause realloc of the whole environ array, and
therefore change of its pointer value. That was exactly the case
in os.environ() - it was using value of environ array remembered
when Tarantool started.

And os.setenv() could realloc the array and turn the saved pointer
into garbage.

Closes #4733

Revert "build: introduce LUAJIT_ENABLE_PAIRSMM flag"

Related to #4770

Enabled Tarantool performance testing on Gitlab-CI for release/master
branches and "*-perf" named branches. For this purpose 'perf' and
'cleanup' stages were added into Gitlab-CI pipeline.

Performance testing support next benchmarks:

- cbench
- linkbench
- nosqlbench (hash and tree Tarantool run modes)
- sysbench
- tpcc
- ycsb (hash and tree Tarantool run modes)

Benchmarks use scripts from repository:
http://github.com/tarantool/bench-run

Performance testing uses docker images, built with docker files from
bench-run repository:

- perf/ubuntu-bionic:perf_master           -- parent image with
                                              benchmarks only
- perf_tmp/ubuntu-bionic:perf_<commit_SHA> -- child images used for
                                              testing Tarantool sources

@Totktonada: Harness and workloads are to be reviewed.

After 7fd6c809
(buffer: port static allocator to Lua) uri started to use
static_allocator - cyclic buffer that also is used in
several modules.

However situation when uri.format output is zero-length
string was not handled properly and ffi.string could
return data that was previously written in static buffer
because use as string terminator the first zero byte.

To prevent such situation let's pass result length explicitly.

Closes #4779