This change does not affect distribution but simply separates the two
concepts of connection ID (ip:port pair) and alias (value set via the
"alias" connection parameter), the method getConnectionByAlias() has
been added to reflect this change.
The method getConnectionBySlot() has also been added.
When using replication backends, now the role of a connection is not
defined by its alias but by the new connection parameter "role" that
can be set to "master", "slave" and (for redis-sentinel) "sentinel".
This also led to a redesign of how connections can be retrieved from
replication backends: the method getConnectionById() now retrieves a
connection only by its ID (ip:port pair), to get a connection by its
alias there is the new method getConnectionByAlias(). This method is
not supported by the redis-sentinel backend due to its dynamic nature
(connections are retrieved and initialized at runtime from sentinels)
but it is still possible to get a single connection from the pool by
using its ID. It is also possible to retrive a connection by its role
using the method getConnectionByRole().
NOTE: the "role" parameter is an hint for the internals of aggregate
connection backends so it is still possible that the actual role of
a connection changes during the execution of a script (e.g. a slave
gets promoted to the role of master): in this case the parameters of
that connection will not be changed as they are immutable, but the
method getConnectionByRole() will return the appropriate connection.
Predis\Client::getClientBy() has been updated with the addition of
"role" and "alias" as supported selectors.
In addition to that, the methods askSlotsMap() and buildSlotsMap() of
the redis-cluster connection backend have been renamed respectively
to askSlotMap() and buildSlotMap().
By default Predis chooses automatically which hash generator to use:
if a suitable version of ext-phpiredis is loaded (that is, a version
that implements the phpiredis_utils_crc16() function) it uses the new
Predis\Cluster\Hash\PhpiredisCRC16 generator, otherwise it falls back
to the usual pure-PHP Predis\Cluster\Hash\CRC16 generator.
Generating the hash of a string of 10 bytes is 10 times faster than
the equivalent pure-PHP implementation of CRC16 (PHP 7.0.7).
This generator requires a version of phpiredis that implements the
function "phpiredis_utils_crc16()".
This method improves the previous one, which worked only by picking a
connection by ID, allowing users to specify a selector type among the
following ones: "id", "key", "slot", "command". These selectors are
expanded internally to methods, invoked against the connection object
in use by the client, that follow the getConnectionByXXX() convention
already in use through the library:
id => getConnectionById()
key => getConnectionByKey()
slot => getConnectionBySlot()
command => getConnectionByCommand()
The underlying connection does not necessarily need to implement the
aggregate connection interface as the client relies on a duck-typing
approach by using method_exists().
This should not break existing code but allows users to retrieve more
easily the current dispatcher loop instance without resorting to some
tricks (like relying on the "use()" directive with closures).
This new method acts exactly like "getClientFor()" by returning a new
client instance for the specified node unless a callback is passed as
the second argument, in this case the callback is invoked and the new
client instance is passed to it. The value returned by the callback
is used as the return value of the "on()" method.
Promoted the "switchToMaster()" and "switchToSlave()" methods to be
part of the replication connection interface and demoted the method
"switchTo($connection)".
All option classes have been moved in the Predis\Configuration\Option
namespace and some have been optimized to have less impact on client
initialization timings.
Furthermore the accepted values for some options have been changed,
this is the complete list of accepted values:
- _aggregate_: callable returning an aggregate connection.
- cluster: string value ("predis", "redis"), callable returning an
aggregate connection.
- replication: string value ("predis", "sentinel"), callable returning
an aggregate connection.
- commands: command factory, named array mapping command IDs to PHP
classes, callable returning a command factory or a named array.
- connections: connection factory, callable returning a connection
factory, named array mapping connection schemes to PHP classes.
- _prefix_: string value, command processor, callable.
- _exceptions_: boolean value.
Note that the cluster and replication options now return a closure
acting as initializer instead of an aggregate connection.
By default Predis now uses a convention-over-configuration approach
by looking for a command class in the Predis\Command\Redis namespace
if it is not already defined in the commands class map.
This change allow us to decrease the time needed to load Predis on
each request since we removed 99% of the mappings in the commands
class map. Classes defined in the internal class map still take the
precedence over this mechanism, so users can still define their own
command classes to handle each command.
This change reduces some unnecessary complexity in the library, Redis
commands do not change much after all. Developers can still implement
their own commands factory, inject new commands or override existing
ones. The "profile" client options has been renamed to "commands" and
it accepts instances of Predis\Command\FactoryInterface.
The test suite checks at runtime the version of the running instance
of Redis for integration tests to adapt itself automatically.
Iterating over Predis\Connection\Aggregate\RedisCluster returns all
the connections currently mapped in the slots map instead of just the
ones initialized in the pool.
When the slots map is retrieved from Redis (which by default is done
automatically) this allows to iterate over all of the current master
nodes of the cluster. When the underlying use of "CLUSTER SLOTS" is
disabled the iteration returns only connections with a slots range
associated in their parameters or initialized by `-MOVED` responses
to make the behaviour of the iteration consistent between the two
modes of operation.
When various nodes in the configuration are unreachable while trying
to send a command, we should attempt to contact a reachable node to
fetch an updated slots map up to $retryLimit times or until there are
no more servers in the pool before giving up.
It is possible that the slots map fetched from Redis contains stale
data and points to a dead server, this happens when the nodes still
have to agree that a master server is down before promoting a slave
to the role of master. In this case no further attempts to execute
the command are performed and an exception is thrown.
This still needs some more testing and will delay v1.0.4 a few days
past its scheduled release.
Daniele Alessandri
Pascal Hofmann