NAME

       MR::IProto - iproto network protocol client

SYNOPSIS

       IProto client can be created with full control of its behaviour:

           my $client = MR::IProto->new(
               cluster => MR::IProto::Cluster->new(
                   servers => [
                       MR::IProto::Cluster::Server->new(
                           host => 'xxx.xxx.xxx.xxx',
                           port => xxxx,
                       ),
                       ...
                   ],
               ),
           );

       Or without it:

           my $client = MR::IProto->new(
               servers => 'xxx.xxx.xxx.xxx:xxxx,xxx.xxx.xxx.xxx:xxxx',
           );

       Messages can be prepared and processed using objects (requires some more CPU):

           my $request = MyProject::Message::MyOperation::Request->new(
               arg1 => 1,
               arg2 => 2,
           );
           my $response = $client->send($request);
           # $response isa My::Project::Message::MyOperation::Response.
           # Of course, both message classes (request and reply) must
           # be implemented by user.

       Or without them:

           my $response = $client->send({
               msg    => x,
               data   => [...],
               pack   => 'xxx',
               unpack => sub {
                   my ($data) = @_;
                   return (...);
               },
           });

       Messages can be sent synchronously:

           my $response = $client->send($response);
           # exception is raised if error is occurred
           # besides $@ you can check $! to identify reason of error

       Or asynchronously:

           use AnyEvent;
           my $callback = sub {
               my ($reply, $error) = @_;
               # on error $error is defined and $! can be set
               return;
           };
           $client->send($request, $callback);
           # callback is called when reply is received or error is occurred

       It is recommended to disconnect all connections in child after fork() to prevent possible
       conflicts:

           my $pid = fork();
           if ($pid == 0) {
               MR::IProto->disconnect_all();
           }

DESCRIPTION

       This client is used to communicate with cluster of balanced servers using iproto network
       protocol.

       To use it nicely you should to implement two subclasses of MR::IProto::Message for each
       message type, one for request message and another for reply.  This classes must be named
       as "prefix::*::suffix", where prefix must be passed to constructor of MR::IProto as value
       of "prefix" attribute and suffix is either "Request" or "Response".  This classes must be
       loaded before first message through client object will be sent.

       To send messages asynchronously you should to implement event loop by self.  AnyEvent is
       recommended.

ATTRIBUTES

       prefix
           Prefix of the class name in which hierarchy subclasses of MR::IProto::Message are
           located. Used to find reply message classes.

       cluster
           Instance of MR::IProto::Cluster. Contains all servers between which requests can be
           balanced.  Also can be specified in servers parameter of constructor as a list of
           "host:port" pairs separated by comma.

       max_parallel
           Max amount of simultaneous request to all servers.

       max_request_retries
           Max amount of request retries which must be sent to different servers before error is
           returned.

       retry_delay
           Delay between request retries.

PUBLIC METHODS

       new( [ %args | \%args ] )
           Constructor.  See "ATTRIBUTES" and "BUILDARGS" for more information about allowed
           arguments.

       send( [ $message | \%args ], $callback? )
           Send $message to server and receive reply.

           If $callback is passed then request is done asynchronously and reply is passed to
           callback as first argument.  Method must be called in void context to prevent possible
           errors.  Only client errors can be raised in async mode. All communication errors are
           passed to callback as second argument. Additional information can be extracted from $!
           variable.

           In sync mode (when $callback argument is skipped) all errors are raised and $! is also
           set. Response is returned from method, so method must be called in scalar context.

           Request $message can be instance of MR::IProto::Message subclass.  In this case reply
           will be also subclass of MR::IProto::Message.  Or it can be passed as "\%args" hash
           reference with keys described in "_send".

       send_bulk( \@messages, $callback? )
           Send all of messages in "\@messages" and return result (sync-mode) or call callback
           (async-mode) after all replies was received.  Result is returned as array reference,
           which values can be instances of MR::IProto::Response or MR::IProto::Error if request
           was passed as object, or hash with keys "data" and "error" if message was passed as
           "\%args".  Replies in result can be returned in order different then order of
           requests.

           See "_send" for more information about message data. Either $message or "\%args"
           allowed as content of "\@messages".

       disconnect_all
           Class method used to disconnect all iproto-connections. Very useful in case of fork().

PROTECTED METHODS

       BUILDARGS( [ %args | \%args ] )
           For compatibility with previous version of client and simplicity some additional
           arguments to constructor is allowed:

           servers
               "host:port" pairs separated by comma used to create MR::IProto::Cluster::Server
               objects.

           timeout, tcp_nodelay, tcp_keepalive, dump_no_ints
               Are passed directly to constructor of MR::IProto::Cluster::Server.

           balance
               Is passed directly to constructor of MR::IProto::Cluster.

           See "BUILDARGS" in Mouse::Manual::Construction for more information.

       _send( [ $message | \%args ], $callback? )
           Pure asyncronious internal implementation of send.

           $message is an instance of MR::IProto::Message.  If "\%args" hash reference is passed
           instead of $message then it can contain following keys:

           msg Message code.

           key Depending on this value balancing between servers is implemented.

           data
               Message data. Already packed or unpacked. Unpacked data must be passed as array
               reference and additional parameter pack must be passed.

           pack
               First argument of pack function.

           unpack
               Code reference which is used to unpack reply.

           no_reply
               Message have no reply.

           retry
               Is retry is allowed. Values of attributes "max_request_retries" and "retry_delay"
               is used if retry is allowed.

           is_retry
               Callback used to determine if server asks for retry. Unpacked data is passed to it
               as a first argument.

SEE ALSO

       MR::IProto::Cluster, MR::IProto::Cluster::Server, MR::IProto::Message.