The Listener::create method now takes a set of configuration parameters
from which it constructs a listener. This removes the duplicated code and
makes the behavior of listener creation similar to other objects in
MaxScale. It also allows the configuration parameters to be stored in the
listener object itself.
The configuration mechanism consists of the following concepts:
Specification
Specifies the available configuration parameters of a module,
their names and their types.
Param
Specifies a parameter, its name and its type.
Type
Specifies the type of a configuration parameters; Bool, Size,
Count, etc.
Configuration
Specifies the configuration values of a particular instance of
the module. Configuration walks hand in hand with Specification,
the latter specifies what the former should contain.
A Specification is capable of configuring a Configuration from a
MXS_CONFIG_PARAMETER, checking in the process that all parameters
are of the correct type and that the required parameters are present.
A Specification is capable of persisting itself so that it later
can be read back.
The mechanism is closed for modification but open for extension in
the sense that if a module requires a custom parameter, all it needs
to do is to derive one class from Param and another from Type.
The canonical way for using this mechanism is as follows. Consider
a module xyx that has three parameters; a parameter called
"enabled" that is of boolean type, a parameter called "period"
that is of duration type, and a parameter "cache" that is of
size type. That would be declared as follows:
// xyz.hh
class XYZSession;
class XYZ : public maxscale::Filter<XYZ, XYZSession>
{
public:
static XYZ* create(const char* zName, MXS_CONFIG_PARAMETER* pParams);
private:
XYZ();
static config::Specification s_specification;
static config::ParamBool s_enabled;
static config::ParamDuration<std::chrono::seconds> s_period;
static config::ParamSize s_cache;
config::Configuration m_configuration;
config::Bool m_enabled;
config::Duration<std::chrono::seconds> m_period;
config::Size m_cache;
};
// xyz.cc
config::Specification XYZ::s_specification(MXS_MODULE_NAME);
config::ParamBool XYZ::s_enabled(
&s_specification,
"enabled",
"Specifies whether ... should be enabled or not."
);
config::ParamDuration<std::chrono::seconds> XYZ::s_period(
&s_specification,
"period",
"Specifies the period. Rounded to the nearest second."
);
config::ParamSize XYZ::s_cache(
&s_specification,
"cache",
"Specifies the size of the internal cache."
);
XYZ::XYZ()
: m_configuration(&s_specification)
, m_enabled(&m_configuration, &s_enabled)
, m_period(&m_configuration, &s_period)
, m_cache(&m_configuration, &s_cache)
{
}
XYZ* XYZ::create(const char* zName, MXS_CONFIG_PARAMETER* pParams)
{
XYZ* pXyz = new XYZ;
if (!s_specification.configure(pXyz->m_configuration, pParams))
{
delete pXyz;
pXyz = nullptr;
}
return pXyz;
}
The helper function makes it easier to convert enum values at runtime to
their integer representation. Also changed the configuration processing
code to use the new function.
The parameters are now written in the order they appear in the module
parameter definitions. Also enabled a previously disabled part in
server unit test.
Added a new module parameter type to be used for parameters
that specify a duration. With the suffixes 'h', 'm', 's' and
'ms' the duration can be specified in hours, minutes, seconds
or milliseconds, respectively.
Irrespective of how the duration is specified, it is always
returned as milliseconds.
For backward compatibility, when a duration value is read it must
be specifed how a value *not* defined using a suffix should be
interpreted; as seconds or milliseconds.
value = param->get_duration(name, mxs::config::INTERPRET_AS_SECONDS);
Replaces uses of config_get_param() in modules either with contains()
or get_string(). The config_get_param() is moved to internal headers,
as it allows seeing inside a config setting.
All global parameters are now handled by the runtime configuration
modification code. The parameters that are trivial to update can now be
updated at runtime. All other global parameters cause a new error message
to be returned stating that the parameter in question cannot be modified
at runtime.
Also updated the list of modifiable parameters in MaxCtrl. This list
should not be stored in MaxCtrl and should be created by MaxScale at
runtime.
See script directory for method. The script to run in the top level
MaxScale directory is called maxscale-uncrustify.sh, which uses
another script, list-src, from the same directory (so you need to set
your PATH). The uncrustify version was 0.66.
The services, monitors and filters now construct the JSON format
parameters from the configuration parameters. This reduces the need for
the amount of explicit operations and makes adding new parameters easier.
Putting the file descriptor first keeps it in line with dprintf.
Making the parameter set an initializer list allows matching against
multiple sets of parameters in one function call. This will compact the
parameter serialization by using the same code for the common service
parameters and the module parameters.
The functions dump of parameters only if they differ from the
defaults. The check for equality is rather coarse but it should work as
long as all core objects use C++ types correctly e.g. integer are not used
to store boolean values (I'm looking at you, enable_root and
localhost_match_wildcard_host). The boolean type has a specialization to
convert the value to the string format used for all defaults in the core.
This also adds the missing return value checks to the dprintf calls and
reports errors if any are encountered.
The ssl parameters were defined as strings even thought they were actually
enums. The events parameter was also a string even though it was an enum.
Also added the missing "all" value to the events enum. This fixes the
regression of scripts not being launched on all events by default.
Moved the definition of the default version string where it should be and
removed the empty value check.
The get_suffixed_size function is now exposed in the internal config
header and it also checks for the validity of the size types.
Took the new function into use and added the appropriate error messages.
Enabling it with a value of 1 should remove the vast majority of
connection related problems that appear in MaxScale. This should filter
out most of the errors caused by transient network problems.
Comparing two fixed std::strings would have equal C strings but comparing
with operator== they would be different. This was a result of the string
modification done by fix_object_name.
Converted the internal header into a C++ header, added std::string
overload and fixed use of the function.
