This is the first in a series of commits that introduce components
that allow filters to be tested without MaxScale or backends.
Obviously the environment is not suited for all cases, but allow e.g.
the behaviour of the firewall filter to be tested in isolation.
The environment consists of helper classes loading and manipulating
modules and filters and mock-classes that provide the needed
scaffolding around a filter.
Currently all components exist under the test directory of the firewall
filter, but once proven they can be moved to a more general purpose
location.
The setting limits the maximum time a MASTER_GTID_WAIT-function
can wait. To work around this limitation, the function is now called
in a loop such that the total timeout is approximately equal to
the requested timeout.
Slave redirection is a special case, as there the total failure
is only known after all redirects have been attempted. In the
failure case, all errors from connections are gathered to one
message.
By using an the value of a global incremented integer as the
initial version number of a Dbfw instance it is ensured that every
such instance does not "inherit" any rules from a previous instance
that happened to exist in the same place as the new instance to be
created.
The error message was not 100% accurate about the value. In addition to
that, neither the value itself nor the monitor or parameter names were
printed in the error message.
The state of the monitored servers is only persisted if the states of the
servers have changed. This removes the unnecessary disk IO caused by the
writing on the monitor journal.
Adds an option 'reply_time' to log_data. When enabled, query execution time
in milliseconds is logged. Execution time is measured as the time between
routeQuery and the first clientReply.
If a server goes down and it has the stale master bit enabled, all other
bits for the server are cleared. This allows failed masters that have been
replaced to be first detected and then reintroduced into the replication
topology.
Only if the filter is in blocking mode, will a match cause an error
to be returned. Thus, no point in creating the error message unless
the filter is in blocking mode.
Whether or not a match causes the query to be blocked or to be allowed
depends on whether the filter is in white-listing or black-listing mode,
so better if the text is neutral.
Using 'not_function' it is possible to match functions other than
a specific set of ones. That will make it significantly easier to
allow certain functions to be used with certain columns.
The special handling of no arguments to `function` in conjunction
with an allowing filter has been removed. The same effect can now
be achieved, without special handling, using `not_function`, no
arguments and a blocking filter.
Implementation will follow in a subsequent commit.
With "--daemon" or "-n" MaxScale can now be told to run in daemon
mode, that is, it forks and the parent exits. This is the default
behaviour, but a flag to this effect is needed if the default
behaviour is changed.
MaxScale now refuses to run as root. However, it is possible to
start MaxScale as root, as long as a user to run MaxScale as is
provided as a command line argument.
It is possible to run as root by invoking MaxScale as root and
by specifying the MaxScale user to be root.
Only used in conjunction with queued connections, which are not
enabled anyway. Once that comes on the table again, better to use
some standard data structures.
The slave and stale slave status bits should be cleared from a master if
it still has them.
Also used the correct functions to manipulate the bits instead of directly
setting them in the monitor.
The value of the global gtid_slave_pos is only needed during
failover, so querying it every monitor loop is unnecessary. The
value is now only requested when deciding on a new master server
or when waiting for the selected promotion target to clear its
relay logs.
Also, when waiting for the logs to clear, gtid_io_pos must stay
constant or failover is cancelled. Io_pos advancing indicates that
the server is still receiving events from the old master.
This commit introduces maxscale::future, maxscale::packaged_task
and maxscale::thread that are modeled after C++11 std::future,
std::packaged_task and std::thread as described here:
http://en.cppreference.com/w/cpp/thread
The standard classes rely upon rvalue references (and move
constructors) introduced by C++11. As the C++ compilers we must use
are pre-C++11 that feature is obviously not present. The absence of
rvalue references is circumvented by implementing regular copy
constructors and assignment operators as if the arguments were rvalue
references.
In practice the above means that when one of these objects are copied,
the state is _moved_ rendering the copied object in default initialized
state. Some care is needed to ensure that unintended copying does not
occur.
The transaction safety was checked even if master GTID registration was
disabled. This always caused a failure when the router was started without
the transaction safety parameter.
As transaction safety is required by the GTID registration, it is not very
helpful to refuse to start if an invalid set of options is detected. To
make usage of the master GTID registration easier, the transaction safety
is also automatically enabled.
The Gtid_Slave_Pos returned by SHOW ALL SLAVES STATUS is not quite
reliable (MDEV-14182) so the variable version is used instead. Added
a convenience function for querying a single row of values.
Also, gtid_strict_mode, log_bin and log_slave_updates are now
queried during failover. The first only causes a warning message
if disabled, the last two affect new master selection.
The two depended on the PCRE2 and Connector-C libraries which means that
the libraries need to be built first. This information needs to be told to
CMake with the add_dependency call.
Gtid_Slave_Pos may contain multiple triplets even with single-source
replication if the domain has changed at some point. For failover, we
only need to know the current domain values, so the gtid-parsing now
accepts an optional domain parameter. The Gtid-class still only stores
one triplet of values.
When parsing the Show Slave Status result, Gtid_IO_Pos is parsed first.
The resulting domain is then read from Gtid_Slave_Pos.
When selecting the new master server, Gtid_IO_Pos is checked to
select the slave with the latest event in relay log. If there is a
tie, the slave that has processed most events wins.
It's possible that the winning slave has unprocessed events. In
this case, failover waits for the slave to complete processing the
log. The maximum wait is defined in monitor parameter
"failover_timeout", defaulting to 90 seconds. If time runs out
failover ends in failure.
The Gtid struct was separated to its own definition to handle gtid:s
easier.
From the documentation:
* `never`: When there is an active transaction, no data will be returned
from the cache, but all requests will always be sent to the backend.
The cache will be populated inside _explicitly_ read-only transactions.
Inside transactions that are not explicitly read-only, the cache will
be populated _until_ the first non-SELECT statement.
* `read_only_transactions`: The cache will be used and populated inside
_explicitly_ read-only transactions. Inside transactions that are not
explicitly read-only, the cache will be populated, but not used
_until_ the first non-SELECT statement.
* `all_transactions`: The cache will be used and populated inside
_explicitly_ read-only transactions. Inside transactions that are not
explicitly read-only, the cache will be used and populated _until_ the
first non-SELECT statement.
