Get rid of duplicated fiber on stop logic.

Prerequisites: #1254

To apply replicated rows in parallel, we need to be able to complete
transactions asynchronously, from the tx_prio callback. We can't yield
there so we must ensure that on_commit/on_rollback triggers don't yield.
The only place where we may yield in a completion trigger is vinyl DDL,
which submits vylog records and waits for them to complete.

Actually, there's no reason to wait for vylog write to complete, as we
can handle missing records on recovery. So this patch reworks vylog to
make vy_log_tx_try_commit() and hence on_commit/on_rollback triggers
using it non-yielding.

To achieve that, we need to:

 - Use vy_log.latch only to sync log rotation vs writes. Don't protect
   vylog buffer with it. This makes vy_log_tx_begin() non-yielding.

 - Use a separate list and buffer for storing vylog records of each
   transaction. We used to share them among transactions, but without
   vy_log.latch we can't sync access to them anymore. Since vylog
   transactions are rare events, this should be fine.

 - Make vy_log_tx_try_commit() append the transaction to the list of
   pending transactions and wake up a background fiber to flush all
   pending transactions. This way it doesn't need to yield.

Closes #4218

Receive function behaved inconsistently for the cases where
first we use an integer as a pattern as to tell the function
a specific number of elements we want to read, and then
perform another receive call using '*a' as a pattern.
The latter should have denoted that we want to get all there
is to get, but instead it was possible to get only a part of
data and also in non-sequential order.

Closes #4118

URI reconfiguration causes incarnation increment in order to
forcefully rewrite old value on remote instances. But that update
was not delivered to a user via triggers. The patch fixes that.

Add 'decimal' to a built-in modules list to preserve
package.loaded.decimal when pretest_clean is set in suite.ini.

Needed for #692.

Built-in modules are bundled into tarantool in the following way. A lua
file from src/lua or src/box/lua is stored as a string literal in a C
file, then built and linked into tarantool. During startup tarantool
calls luaL_loadbuffer() on this string.

When a Lua source is converted to a C literal, proper escaping is
performed. However there is one case, which was not covered: trigraphs.
The patch adds escaping of question mark symbols to avoid matching ??X
sequences as trigraphs by C preprocessor.

The most simple way to check that it works is to apply the following
patch:

 | diff --git a/src/lua/string.lua b/src/lua/string.lua
 | index 6e12c59ae..2da2dbf4d 100644
 | --- a/src/lua/string.lua
 | +++ b/src/lua/string.lua
 | @@ -425,3 +425,6 @@ string.fromhex    = string_fromhex
 |  string.strip      = string_strip
 |  string.lstrip      = string_lstrip
 |  string.rstrip      = string_rstrip
 | +string.foo = function()
 | +    return '??('
 | +end

And call the function like so:

 | ./src/tarantool -e 'print(string.foo()) os.exit()'

If it printfs `??(`, then everything is okay. If it prints `[`, then
`??(` was preprocessed as the trigraph.

We hit this problem when tried to bundle luarocks-3: it contains
"^(.-)(%??)$" regexp, where `??)` was interpreted as `]`. Debug build or
a build with -DENABLE_WERROR reports an error in the case, but usual
RelWithDebInfo build passes (with -Wtrigraphs warnings) and can show
this unexpected behaviour.

Fixes #4291.

vy_tx_handle_deferred_delete() expects (righteously) that in case a
deferred DELETE overwrites a statement in a secondary index write set
and the overwritten statement wasn't skipped on commit (i.e. doesn't
have txv->is_overwritten flag set), both the old and the new statement
must be REPLACEs (see the comment to the corresponding assertions for
more details).

The problem is we don't set is_overwritten flag in case a statement
doesn't have any effect (txv->is_nop is set), even if it was, in fact,
overwritten in the primary index write set (see vy_tx_prepare). As
a result, we get an assertion failure when we delete such statement
in the same transaction, e.g.

  s = box.schema.space.create('test', {engine = 'vinyl'})
  s:create_index('pk', {parts = {1, 'unsigned'}})
  s:create_index('sk', {parts = {2, 'unsigned'}})
  s:replace{1, 1, 1}
  box.begin()
  s:update(1, {{'+', 3, 1}}) -- adds no-op REPLACE to sk write set
  s:delete(1)                -- produces deferred DELETE for sk
  box.commit()

results in

  vy_tx_handle_deferred_delete: Assertion `vy_stmt_type(stmt) == IPROTO_REPLACE' failed.

Fix this by making sure we set is_overwritten for all overwritten
statements in a secondary index write set.

Closes #4294

The test used to fail occasionally with a following error:

```
[001] box/net.box.test.lua                                            [ fail ]
[001]
[001] Test failed! Result content mismatch:
[001] —- box/net.box.result  Thu Jun 13 06:16:34 2019
[001] +++ box/net.box.reject  Fri Jun 14 04:50:55 2019
[001] @@ -3774,23 +3774,23 @@
[001]  ...
[001]  test_run:grep_log('default', 'Got a corrupted row.*')
[001]  —-
[001] — 'Got a corrupted row:'
[001] +- null
[001]  ...
[001]  test_run:grep_log('default', '00000000:.*')
[001]  —-
[001] — '00000000: A3 02 D6 5A E4 D9 E7 68 A1 53 8D 53 60 5F 20 3F '
[001] +- null
[001]  ...
[001]  test_run:grep_log('default', '00000010:.*')
[001]  —-
[001] — '00000010: D8 E2 D6 E2 A3 02 D6 5A E4 D9 E7 68 A1 53 8D 53 '
[001] +- null
[001]  ...
[001]  test_run:grep_log('default', '00000020:.*')
[001]  —-
[001] — '00000020: 60 5F 20 3F D8 E2 D6 E2 A3 02 D6 5A E4 D9 E7 68 '
[001] +- null
[001]  ...
[001]  test_run:grep_log('default', '00000030:.*')
[001]  —-
[001] — '00000030: A1 53 8D 53 60 5F 20 3F D8 E2 D6 E2 '
[001] +- null
[001]  ...
[001]  test_run:grep_log('default', '00000040:.*')
[001]  —-
```

This happened because we used `grep_log` right after `socket:write`,
which should cause the expected log messages. Change to `wait_log`.

Follow-up #4273

* Added a new command `test` that is new feature of luarocks 3.x.
* Added a new command `make_manifest` that is command from
  luarocks-admin.
* Added a new command `help` for getting help of internal luarocks
  commands.

Also refined arguments descriptions of existing tarantoolctl rocks
commands.

Made tarantoolctl compatible with luarocks-3.x.

Fixes #4052.

**Intro**:

By default, Lua uses package.path/cpath to load dependencies when user
calls `require("something")`. It also allows to add custom loaders to
extend its functionality. Tarantool transforms default behavior by
injecting some custom loaders into `package.loaders`.

Firstly, it allows to load modules from CWD. Secondly, it looks for
rocks modules starting from CWD and traversing up to root "/"
directory. This "start from CWD" behaviour is hardcoded and not
customizable.

**Problem**:

Let say we have a lua app with all dependencies under myapp directory.
If you start your application like this, you won't be able to load any
of them unless you specify myapp in every require call:

```bash
tarantool myapp/init.lua
```

To allow user scripts require dependencies relatively, user has to first
determine appropriate directory path relatively to scripts file and then
patch package.path/cpath with both modules and rocks paths.

**Solution**:

Introduce the notion of a search root which is used as base for rocks
and module loaders. Let user easily set this path to control how
application dependencies are loaded.

There is 2 new functions introduced in this patch:
- package.setsearchroot(path) is used to set new search root to look
dependency from
- package.searchroot() returns search root currently setup. If no search
root was setup, `fio.cwd()` is returned.

@TarantoolBot document
Title: Document new package.setsearchroot and package.searchroot
functions

What this patch does:

`package.setsearchroot(path)` function sets search root which is used
as root directory to load dependencies from:

- path must be a string (relative or absolute). It will be expanded to
  absolute path and set as a search root;
- if no path specified, it sets current file directory as a search root
  (using debug.sourcedir);
- if path is box.NULL, that searchroot will be reset,
  so default behaviour will apply (CWD).

With that said everything a user now has to do is to just put this line
of code:

```lua
package.setsearchroot()
```

at the top of project init file "myapp/init.lua" which is placed in the
project root and start an app by simply calling:

```bash
$ tarantool myapp/init.lua
```

This will set search root to the absolute path of `myapp` directory, so
all dependencies will be looked relative to that directory.

Run collectgarbage() between tests to ensure that there are no dangling
iterators and so on. Such objects can affect statistic counters that may
be important for a test.

Fixes #4287.

Iproto already listens for requests during recovery, so yielding at this
point of time allows such early requests, which arrived during recovery,
be processed while data is in unfinished state. This caused box/net.box
test failures, and is potentially harmful.
Besides, there is no need to yield during recovery.

Closes #4273

Add fixed-point decimal type to tarantool core.
Adapt decNumber floating-point decimal library for the purpose, write a
small wrapper and add unit tests.

A new decimal type is an alias for decNumber numbers from the decNumber
library.
Arithmetic operations (+, -, *, /) and some mathematic functions
(ln, log10, exp, pow, sqrt) are available together with methods to
pack and unpack decimal to and from its packed representation (useful
for serialization).

We introduce a single context for all the arithmetic operations
on decimals, which enforces both number precision and scale to be
in range [0, 38]. NaNs and Infinities are restricted.

Part of #692

After this patch, all errors in VDBE will be set using diag_set().

Closes #4074

After this patch, all errors in the SQL functions will be set
using diag_set().

Part of #4074

This patch replaces SQL error SQL_MISMATCH by Tarantool error
ER_SQL_TYPE_MISMATCH.

Since the interrupt system is no longer used in SQL, the
SQL_INTERRUPT error is out of date and should be removed. Also
this patch removes currently unused progress callback system.

Currently, in OP_Halt, you can get a SQL error other than
SQL_TARANTOOL_ERROR, for example, the SQL_CONSTRAINT error. After
this patch, all errors going through OP_Halt will have SQL error
code SQL_TARANTOOL_ERROR and have diag set.

Part of #4074

The ER_SQL error code is very similar to the ER_SQL_EXECUTE error
code: they have almost identical description and usage. To avoid
misunderstandings, it is better to remove one of them. The ER_SQL
error code has a slightly more vague description, so it was
decided to remove it.

The error codes SQL_TARANTOOL_DELETE_FAIL,
SQL_TARANTOOL_ITERATOR_FAIL and SQL_TARANTOOL_INSERT_FAIL have
practically no functions, but their use can lead to incorrect
behavior. This patch replaces them with SQL_TARANTOOL_ERROR. This
will simplify the work with errors.

Currently, the mayAbort field is working with SQL error
SQL_CONSTRAINT. Since we want to replace SQL_CONSTRAINT with a
Tarantool error, we need to change the way the mayAbort field
works or delete it. Since this field is used only for make an
assertion in debug mode, it is better to simply remove it.

Fixed test replication/misc to be able to run it on
hosts under high load. Changed downstream check to
use test_run:wait_downstream() function, to wait for
certain box.info.replication values to fix the error:

[050] replication/misc.test.lua                                       [ fail ]
[050]
[050] Test failed! Result content mismatch:
[050] --- replication/misc.result	Thu Jun  6 06:46:54 2019
[050] +++ replication/misc.reject	Fri Jun  7 05:55:00 2019
[050] @@ -622,7 +622,7 @@
[050]  ...
[050]  box.info.replication[2].downstream.status
[050]  ---
[050] -- stopped
[050] +- follow
[050]  ...
[050]  test_run:cmd("stop server replica")
[050]  ---

Closes #4277

Added to cmake environment CMAKE_DL_LIBS (The name of the library
that has dlopen and dlclose in it, usually -ldl) to openssl build
to add DL library, to fix the following fails:

Linking CXX executable crypto.test
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_globallookup':
dso_dlfcn.c:(.text+0x11): undefined reference to `dlopen'
dso_dlfcn.c:(.text+0x24): undefined reference to `dlsym'
dso_dlfcn.c:(.text+0x2f): undefined reference to `dlclose'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_bind_func':
dso_dlfcn.c:(.text+0x334): undefined reference to `dlsym'
dso_dlfcn.c:(.text+0x3f2): undefined reference to `dlerror'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_load':
dso_dlfcn.c:(.text+0x459): undefined reference to `dlopen'
dso_dlfcn.c:(.text+0x4c9): undefined reference to `dlclose'
dso_dlfcn.c:(.text+0x502): undefined reference to `dlerror'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_pathbyaddr':
dso_dlfcn.c:(.text+0x5a1): undefined reference to `dladdr'
dso_dlfcn.c:(.text+0x601): undefined reference to `dlerror'
/usr/local/lib64/libcrypto.a(dso_dlfcn.o): In function `dlfcn_unload':
dso_dlfcn.c:(.text+0x662): undefined reference to `dlclose'
collect2: error: ld returned 1 exit status
make[2]: *** [test/unit/crypto.test] Error 1
make[1]: *** [test/unit/CMakeFiles/crypto.test.dir/all] Error 2

Closes #4245

Removes the following unused macros:
SQL_OMIT_AUTOINCREMENT
SQL_OMIT_CONFLICT_CLAUSE
SQL_OMIT_PRAGMA
SQL_PRINTF_PRECISION_LIMIT
SQL_OMIT_COMPOUND_SELECT
SQL_POWERSAFE_OVERWRITE
SQL_OMIT_PROGRESS_CALLBACK
SQL_OMIT_AUTORESET
SQL_OMIT_DECLTYPE
SQL_ENABLE_COLUMN_METADATA
SQL_TRACE_SIZE_LIMIT
SQL_OMIT_LIKE_OPTIMIZATION
SQL_OMIT_OR_OPTIMIZATION
SQL_OMIT_BETWEEN_OPTIMIZATION
SQL_EXPLAIN_ESTIMATED_ROWS
SQL_ENABLE_COLUMN_USED_MASK
SQL_DISABLE_DIRSYNC
SQL_DEBUG_SORTER_THREADS
SQL_DEFAULT_WORKER_THREADS
SQL_LIMIT_WORKER_THREADS
SQL_MAX_WORKER_THREADS
SQL_ENABLE_MEMORY_MANAGEMENT
SQL_ENABLE_UNKNOWN_SQL_FUNCTION
SQL_SUBSTR_COMPATIBILITY
SQL_ENABLE_STMT_SCANSTATUS
Removed the remains of multithreading in the VDBE
sorting tools.
Updates tests.

Closes #3978

As alter schema triggers lifecycle is bound with a transaction
so corresponding structures should be placed onto a txn memory
region instead of a fiber gc space.

Prerequisites: #1254

We tend to synchronize cached data with the actual data changes: apply
while on_replace and undo while on_rollback.

Fire transaction trigger after a transaction finalization. This allows
to not to view the transaction dismissed changes in case of rollback.

Fixes: #4276

SWIM as a monitoring module is hard to use without an ability to
subscribe on events. Otherwise a user should have polled a SWIM
member table for updates - it would be too inefficient.

This commit exposes an ability to set Lua triggers.

Closes #4250

@TarantoolBot document
Title: SWIM: swim:on_member_event

Now a user can set triggers on member table updates. There is a
function for that, which can be used in one of several ways:
```Lua
swim:on_member_event(new_trigger[, ctx])
```
Add a new trigger on member table update. The function
`new_trigger` will be called on each new member appearance, an
existing member drop, and update. It should take 3 arguments:
first is an updated SWIM member, second is an events object,
third is `ctx` passed as is.

Events object has methods to help a user to determine what event
has happened.
```Lua
local function on_event(member, event, ctx)
    if event:is_new() then
        ...
    elseif event:is_drop() then
        ...
    end

    if event:is_update() then
        -- All next conditions can be
        -- true simultaneously.
        if event:is_new_status() then
            ...
        end
        if event:is_new_uri() then
            ...
        end
        if event:is_new_incarnation() then
            ...
        end
        if event:is_new_payload() then
            ...
        end
    end
end

s:on_member_event(on_event, ctx)
```
Note, that multiple events can happen simultaneously. A user
should be ready to that. Additionally, 'new' and 'drop' never
happen together. But they can happen with 'update', easily.
Especially if there are lots of events, and triggers work too
slow. Then a member can be added and updated after a while, but
still does not reach a trigger.

A remarkable case is 'new' + 'new payload'. This case does not
correlate with triggers speed. The thing is that payload absence
and payload of size 0 are not the same. And sometimes is happens,
that a member is added without a payload. For example, a ping
was received - pings do not carry payload. In such a case the
missed payload is received later eventually. If that matters for
a user's application, it should be ready to that: 'new' does not
mean, that the member already has a payload, and payload size
says nothing about its presence or absence.

Second usage case:
```Lua
swim:on_member_event(nil, old_trigger)
```
Drop an old trigger.

Third usage case:
```Lua
swim:on_member_event(new_trigger, old_trigger[, ctx])
```
Replace an existing trigger in-place, with keeping its position
in the trigger list.

Fourth usage case:
```Lua
swim:on_member_event()
```
Get a list of triggers.

When drop or replace a trigger, a user should be attentive - the
following code does not work:
```Lua
tr = function() ... end
-- Add a trigger.
s:on_member_event(tr)
...
-- Drop a trigger.
s:on_member_event(nil, tr)
```
The last line, if be precise. This is because SWIM wraps user
triggers with an internal closure for parameters preprocessing.
To drop a trigger a user should save result of the first
on_member_event() call.

This code works:
```Lua
tr = function() ... end
-- Add a trigger.
tr_id = s:on_member_event(tr)
...
-- Drop a trigger.
s:on_member_event(nil, tr_id)
```

The triggers are executed one by one in a separate fiber. And
they can yield. These two facts mean that if one trigger sleeps
too long - other triggers wait. It does not block SWIM from doing
its routine operations, but block other triggers.

The last point to remember is that if a member was added and
dropped before its appearance has reached a trigger, then such
a member does not fire triggers at all. A user will not notice
that easy rider member.

These function are going to yield in scope of #4250, because
swim:new() will start a fiber, while swim:delete() cancels and
gives it a control.

Needed for #4250

SWIM is asynchronous by design. It means, that there are two
ways of getting updates of a member table and individual members:
polling and triggers. Polling is terrible - this is why libev
with select(), poll(), epoll(), kevent() have appeared. The only
acceptable solution is triggers.

This commit allows to set triggers on member updates.

Part of #4250

It is a miracle, but somehow it worked until I changed a couple
of places. Here objects stored in an rlist are freed, but not
deleted from the list. The list is reused after that.

The SWIM unit tests code with the fake events and time does lots
of forbidden things: it manually invokes pending watcher
callbacks; manages global time without a kernel; puts not
existing descriptors into the loop. These foul blows open the
gates to the full control over IO events, descriptors, virtual
time. Hundreds of virtual seconds pass in milliseconds in
reality, it makes SWIM unit tests fast despite complex logic.

All these actions does not affect the loop until yield. On yield
a scheduler fiber wakes up and

    1) infinitely generates EV_READ on not existing descriptors
       because a kernel considers them closed;

    2) manual pending callbacks invocation asserts, because it is
       not allowed for non-scheduler fibers.

To avoid these problems a new isolated loop is created, not
visible for the scheduler. Here the fake events library can rack
and ruin whatever it wants.

Needed for #4250

When a member is deleted, pointer at its struct tt_uuid becomes
invalid. This commit makes member:uuid() create a new tt_uuid
object, cached for subsequent calls.

Travis-ci failed on brew install python2 due to it was
already installed on OSX 10.13 Sierra, so it needs
to be installed without fails on its exists.

Follow up #4254

Up to this point, the is_temporary flag has been set for surrogate space
definitions used to transfer meta-information during compilation stage
of DML queries (CREATE TABLE/INDEX etc).

At some point, it became possible to use spaces created in Lua in
SQL statements. Since it is allowed to create temporary spaces in
Lua, not all temporary spaces in SQL are surrogate wrappers. To separate
real temporary spaces (i.e. which came from space cache) from surrogate
ones, is_ephemeral flag is now set in such spaces instead of
is_temporary. Note that there can't be mess between these flags since
ephemeral spaces can exist only during execution of VDBE bytecode.
Also note that flag is required only for debugging facilities.

Close #4139

Fixed swim headers in addition to commit:
88892f13 ('swim: fix build on FreeBSD')

Included unistd.h header to fix the following errors:

In file included from src/lib/swim/swim_transport_udp.c:31:
src/lib/swim/swim_transport.h:61:1:
    error: unknown type name 'ssize_t'; did you mean 'size_t'?
ssize_t
^~~~~~~
size_t
/usr/include/netinet6/in6.h:698:18: note: 'size_t' declared here
typedef __size_t        size_t;
                        ^
In file included from src/lib/swim/swim_transport_udp.c:31:
src/lib/swim/swim_transport.h:66:1:
    error: unknown type name 'ssize_t'; did you mean 'size_t'?
ssize_t
^~~~~~~
size_t
/usr/include/netinet6/in6.h:698:18: note: 'size_t' declared here
typedef __size_t        size_t;

Closes #4050

Enabled use_unix_sockets_iproto option to use unix sockets
iproto provides the new way to handle the problem with
'Address already in use' error. It lets test-run appoint
unix sockets for LISTEN environment variable values.

Before this change the TcpPortDispatcher was used to
eliminate the race condition when two workers trying to use
the same port: the idea was that each worker used its own
ports range. Really these ports could race with client ports
(from, say, net.box or replication), which typically didn't
use bind() and so bound to a random available port (despite
any dispatched ranges) and could produce 'Address already in
use' error.

Closes: #4008

Removed skip flag file to switch on the testing of the
http_client test. Enabled http_client test on OSX,
fixed missing of the python2 symlink. Removed the subtest
on '595 error return' from 'error' suite, due to it may
hang forever. To enable test on travis-ci reverted commit:

1d7285c4 ('Disable flaky http_client.test.lua')

Closes #4254