This option must return a callable object that is used to override how
the client aggregates connections when passing an array of parameters
to its constructor.
When specified, this option overrides both "cluster" and "replication"
as it allows to make use of your own code to aggregate multiple nodes.
This is, for example, how you can mimic the standard initialization of
a cluster that relies on client-side sharding:
$parameters = ['tcp://127.0.0.1:6380', 'tcp://127.0.0.1:6381'];
$options = [
'aggregate' => function () {
return function ($parameters, $options) {
$connection = new Predis\Connection\PredisCluster();
$options->connections->aggregate($connection, $parameters);
return $connection;
};
},
];
$client = new Predis\Client($parameters, $options);
When invoked by the client, the specified callable must always return
a Predis\Connection\ConnectionInterface instance or the client will
throw an UnexpectedValueException.
Using list() with the warning suppressor is slower than using isset()
to check the presence of the first two elements of the array returned
by explode(). This also allow us to skip incomplete query string pairs
when parsing the URI string.
We have also changed the exception being thrown on invalid URIs to a
more appropriate one.
The main reason behind that code duplication was performance related
as we tried to reduce method calls when possible, even at the cost of
falling into the realm of early optimizations. Apparently we just lose
~400 req/sec on a 21000 req/sec basis ("SET foo bar") using PHP 5.5.3
(packaged by Ubuntu 13.10) on an Intel Q6600, so we will most likely
stick with this change for the sake of best practices.
The "profile" member is actually used for caching purposes as fetching
its value from the options instance would add noticeable overhead in a
part of the client where every bit of optimization matters, for this
we decided to keep it private.
Despite not being a globally supported feature of Predis anymore, they
are still optionally supported by our default text protocol processors
and they can be used to build custom stuff for specific needs.
Supporting this feature has been problematic and leaded to some ugly
code to make abstractions such as pipelines and transactions aware of
these kind of response objects. Furthermore, it was not possible to
add them to all the connection classes due to implementation limits.
For such reasons Predis do not support them globally anymore, but the
actual classes are still shipped within the library so that they can
be used to build custom stuff at a level lower than client (that is,
unless we decide to remove them for good before going stable).
This commit is a complete rewrite of the classes previously contained
in the Predis\Option namespace aimed at lowering the initialization
overhead while bringing in more consistency. The overall idea is still
the same with a mini DI container, Predis\Configuration\Options, which
carries options with values that can be initialized lazily.
The first difference with our previous implementation is that now even
user-defined options can be initialized lazily, everything needed is
an object responding to the __invoke() magic method such as a closure.
Other kind of callable arguments (strings, arrays) will be treated as
plain values. The only drawback is that we cannot pass any instance of
classes implementing __invoke() as an option value, but considered the
limited scope of our use case we can say it's more of an acceptable
compromise. Callbacks used for lazy initialization will receive two
arguments upon invokation:
- The current instance of Predis\Configuration\Option ($options)
- A string containing the name of the option ($option)
This is an example in actual code:
$options = new Predis\Configuration\Options([
'exceptions' => true,
'profile' => '2.8',
'distributor' => function () {
return new Predis\Cluster\Distribution\KetamaPureRing();
},
'cluster' => function ($options) {
$distr = $options->distributor;
$strategy = new Predis\Cluster\PredisClusterHashStrategy($distr);
$cluster = new Predis\Connection\PredisCluster();
return $cluster;
},
'connections' => function ($options, $option) {
$factory = $options->getDefault($option);
$factory->define('tcp', 'Predis\Connection\PhpiredisConnection');
return $factory;
},
]);
As you can see there's very little difference compared to before in
the actual usage as most changes are under the hood. Some options such
as "exceptions" and "replication" can now correctly parse bool values
from strings (so the string "false" is not evaluated as boolean true).
While options were initially conceived to configure the client and its
behavior, the concept has matured and it's perfectly fine to consider
the use of Predis\Configuration\Options to propagate configurations to
inner parts of the library.
This commit marks the start of works for the next major release of
Predis which will bring various breaking changes needed to polish the
internal design making the library even more flexible to use or extend
and, more importantly, almost stable in terms of API.
The Redis commands API exposed by Predis\Client is not going to change
much if not at all which is a good news. The most immediate changes
affecting developers will involve the renaming of a few namespaces and
classes, the removal of some previously deprecated classes and methods
and some tweaks to the current abstractions.
Right now the plan is to have a fast paced development to release this
version as soon as possible, ideally a few weeks later than Redis 2.8,
then wait to see the final definition of redis-cluster so that we can
tweak our code if needed and finally hit the v1.0.0 milestone with as
few changes as possible. Furthermore, v1.x will most likely be the
last version of Predis supporting PHP 5.3 as we will start migrating
to PHP 5.4 (or even 5.5) with v2.x, which is not going to happen soon
anyway.
This iterator tries to mimic the same behaviour of the cursor-based
iterators implemented upon the SCAN family of commands and offering
only limited guarantees on the returned elements, but uses LRANGE to
fetch items from a list incrementally.
Given the IP address we use for this test (the standard IP assigned by
operating systems when unable to get one lease from a DHCP server), on
certain kernels or network stacks we can get different messages such
as "No route to host". Since we just need to make sure that our test
does not take more than 1 seconds abiding by the sub-second timeout,
we can just live with that.
We are experimenting with a new approach at naming classes using less
redundant names by leveraging the containing namespace. The PHP "use"
directive is not limited to class names but can be used to import the
whole namespace, which means you can do something like this:
use Predis\Collection\Iterator;
// ...
foreach (new Iterator\Keyspace($client) as $key) {
// ...
}
Alternatively you can always rely on "use ... as ..." to import one of
the classes by giving it a more meaningful name in the context of the
root namespace:
use Predis\Collection\Iterator\Keyspace as KeyspaceIterator;
// ...
foreach (new KeyspaceIterator($client) as $key) {
// ...
}
In this specific case we chose to apply the -Key postfix to classes
iterating Redis keys to be more explicit about the fact that those
iterators does not work on local in-memory collections, but fetch
items from a key stored on a remote Redis server.
Daniele Alessandri