Achieving compatibility actually required a few marginal changes:
- HHVM still has some issues with re-entrant calls to __get(). The
applied change is an hack simply because it is ugly, but it is not
wrong and does not break the signature of the options interface.
- Since we cannot rely on the PHP version to detect the availability
of socket_import_stream(), we switched to function_exists(). As an
added bonus, using function_exists() is twice faster.
- In the test suite we removed an assertion for the message of an
E_WARNING simply because HHVM emits a different message. Checking
for the warning is actually enough in that context.
While the whole test suite passes on HHVM 2.3.0, please remember that
HHVM is still in development and things could break anytime especially
in some obscure corner cases.
Using PHP's "parse_str()" to parse the query string is slightly more
efficient then our own code especially when the number of fields in
the query string grows, with the additional benefit of supporting
arrays for values when brackets are present in fieldnames.
So after this commit, providing this URI string:
$string = 'tcp://127.0.0.1?metavars[]=foo&metavars[]=hoge';
Is equivalent to providing the following named array:
$array = [
'scheme' => 'tcp',
'host' => '127.0.0.1',
'metavars' => ['foo', 'hoge'],
];
Aside from this improvement, the URI parsing behavior has not changed.
These parameters are applied only to connections being created on the
fly when not part of the current pool. This condition usually happens
upon -MOVE or -ASK responses returned by Redis to redirect client to
different nodes.
Only named arrays are explicitly accepted now, but the old behaviour
of creating a connection parameters instance out of an URI string or
a named array is still available using the "create()" static method.
$array = ['host' => '127.0.0.1', 'timeout' => 1];
$uri = 'tcp://127.0.0.1?timeout=1';
$parameters = new ConnectionParameters($array); // Arrays only
$parameters = ConnectionParameters::create($array); // Arrays OK
$parameters = ConnectionParameters::create($uri); // Strings OK
The purpose of the change is to have a more concise constructor with a
well defined signature.
List of changes:
- The cluster connection can be initialized with a partial list of
nodes, the full slots map will be fetched from Redis itself using
the CLUSTER NODES command.
- The slots map can be optionally retrieved from Redis if the server
returns a -MOVE response, otherwise only the interested slot will
be permanently reassigned to the new target node.
- $cluster->connect() connects to a random connection in the pool
instead of forcing the connect operation on all the connections.
Status response objects are needed mostly to make it possible from the
client perspective to differentiate a status response with the payload
"OK" from a normale bulk reply containing "OK".
The biggest change is for commands returning +OK responses: these were
previously translated to TRUE (bool value), but they are now returned
as instances of Predis\Response\Status. Just to illustrate an example
of the possibilities with this change we will use SET since it is the
most widely used command returning +OK:
$response = $client->set('foo', 'bar');
echo $response; // 'OK'
$response == 'OK'; // TRUE
isset($response->ok); // TRUE
$response == true; // TRUE
$response === true; // FALSE
$response instanceof Predis\Response\ObjectInterface; // TRUE
$response instanceof Predis\Response\Status; // TRUE
For those checking responses returned by commands such as SET or PONG,
the breaking change basically lies in the usage of strict comparison:
doing $response === true will now evaluate to FALSE instead of TRUE.
By default Predis caches common status responses such as OK or QUEUED
to lower the memory usage when using pipelines or transactions.
This optimization is mostly useful since connection parameters can be
instantiated more than one time in a script when using clustering or
replication.
A profile is not needed to create instances of basic initialization
commands such as AUTH (authentication) and SELECT (database selection)
since they do not need prefixing and other stuff.
If needed, developers can still extend the base connection factory to
make it use a server profile and configure the client to use it using
options.
We must always execute ASKING on the connection identified by the -ASK
response before executing the actual command because not doing so will
break the cluster specifications while redis-cluster is performing a
resharding operation.
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.
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).
Daniele Alessandri
Alexandru Patranescu