This class represents an asynchronous remote procedure call. More...

#include <ClientRPC.h>

Public Types
enum	Status { OK, SERVICE_SPECIFIC_ERROR, RPC_FAILED, RPC_CANCELED, TIMEOUT, INVALID_SERVICE, INVALID_REQUEST }
	The return type of waitForReply(). More...
typedef OpaqueClientRPC::Clock	Clock
	Clock used for timeouts.
typedef OpaqueClientRPC::TimePoint	TimePoint
	Type for absolute time values used for timeouts.
Public Member Functions
	ClientRPC (std::shared_ptr< RPC::ClientSession > session, uint16_t service, uint8_t serviceSpecificErrorVersion, uint16_t opCode, const google::protobuf::Message &request)
	Issue an RPC to a remote service.
	ClientRPC ()
	Default constructor.
	ClientRPC (ClientRPC &&)
	Move constructor.
	~ClientRPC ()
	Destructor.
ClientRPC &	operator= (ClientRPC &&)
	Move assignment.
void	cancel ()
	Abort the RPC.
bool	isReady ()
	Indicate whether a response or error has been received for the RPC.
Status	waitForReply (google::protobuf::Message response, google::protobuf::Message serviceSpecificError, TimePoint timeout)
	Wait for a reply to the RPC or an error.
std::string	getErrorMessage () const
	If an RPC failure occurred, return a message describing that error.
Private Member Functions
	ClientRPC (const ClientRPC &)
ClientRPC &	operator= (const ClientRPC &)
Private Attributes
uint16_t	service
	Identifies the service running on the server.
uint16_t	opCode
	Identifies the remote procedure within the Service to execute.
OpaqueClientRPC	opaqueRPC

Detailed Description

This class represents an asynchronous remote procedure call.

Unlike OpaqueClientRPC, this executes a particular method on a particular service.

TODO(ongaro): This abstraction should ideally contain protocol version negotiation for the higher layer. To do so, we'd want to be able to associate a small amount of state with the session.

Definition at line 41 of file ClientRPC.h.

Member Typedef Documentation

typedef OpaqueClientRPC::Clock LogCabin::RPC::ClientRPC::Clock

Clock used for timeouts.

Definition at line 44 of file ClientRPC.h.

typedef OpaqueClientRPC::TimePoint LogCabin::RPC::ClientRPC::TimePoint

Type for absolute time values used for timeouts.

Definition at line 46 of file ClientRPC.h.

Member Enumeration Documentation

enum LogCabin::RPC::ClientRPC::Status

The return type of waitForReply().

Enumerator:

OK	The service returned a normal response. This is available in 'response'.
SERVICE_SPECIFIC_ERROR	The service threw an error (but at the transport level, the RPC succeeded). Service-specific details may be available in 'serviceSpecificError'.
RPC_FAILED	The server could not be contacted or did not reply. It is unknown whether or not the server executed the RPC. More information is available with getErrorMessage().
RPC_CANCELED	The RPC was aborted using cancel(). It is unknown whether the server executed or will execute the RPC.
TIMEOUT	The RPC did not complete before the given timeout elapsed. It is unknown whether or not the server executed the RPC (yet).
INVALID_SERVICE	The server is not running the requested service.
INVALID_REQUEST	The server rejected the request, probably because it doesn't support the opcode, or maybe the request arguments were invalid.

Definition at line 110 of file ClientRPC.h.

Constructor & Destructor Documentation

LogCabin::RPC::ClientRPC::ClientRPC	(	std::shared_ptr< RPC::ClientSession >	session,
		uint16_t	service,
		uint8_t	serviceSpecificErrorVersion,
		uint16_t	opCode,
		const google::protobuf::Message &	request
	)

Issue an RPC to a remote service.

Parameters:

session	A connection to the remote server.
service	Identifies the service running on the server. See Protocol::Common::ServiceId.
serviceSpecificErrorVersion	This tells the Service what service-specific errors the client understands. Clients can expect services to not send service-specific errors introduced in newer versions, but they should remain compatible with older versions.
opCode	Identifies the remote procedure within the Service to execute.
request	The arguments to the remote procedure.

Definition at line 32 of file ClientRPC.cc.

LogCabin::RPC::ClientRPC::ClientRPC ( )

Default constructor.

This doesn't create a valid RPC, but it is useful as a placeholder.

Definition at line 59 of file ClientRPC.cc.

LogCabin::RPC::ClientRPC::ClientRPC ( ClientRPC && other )

Move constructor.

Definition at line 66 of file ClientRPC.cc.

LogCabin::RPC::ClientRPC::~ClientRPC ( )

Destructor.

Definition at line 73 of file ClientRPC.cc.

LogCabin::RPC::ClientRPC::ClientRPC ( const ClientRPC & ) [private]

Member Function Documentation

ClientRPC & LogCabin::RPC::ClientRPC::operator= ( ClientRPC && other )

Move assignment.

Definition at line 78 of file ClientRPC.cc.

void LogCabin::RPC::ClientRPC::cancel ( )

Abort the RPC.

The caller is no longer interested in its reply.

Definition at line 87 of file ClientRPC.cc.

bool LogCabin::RPC::ClientRPC::isReady ( )

Indicate whether a response or error has been received for the RPC.

Returns:: True means the reply is ready or an error has occurred; false otherwise.

Definition at line 93 of file ClientRPC.cc.

ClientRPC::Status LogCabin::RPC::ClientRPC::waitForReply	(	google::protobuf::Message *	response,
		google::protobuf::Message *	serviceSpecificError,
		TimePoint	timeout
	)

Wait for a reply to the RPC or an error.

Panics if the server responds but is not running the same protocol.

Parameters:

[out]	response	If not NULL, this will be filled in if this method returns OK.
[out]	serviceSpecificError	If not NULL, this will be filled in if this method returns SERVICE_SPECIFIC_ERROR.
[in]	timeout	After this time has elapsed, stop waiting and return TIMEOUT. In this case, response and serviceSpecificError will be left unmodified.

Returns:: See the individual values of Status.

Definition at line 99 of file ClientRPC.cc.

std::string LogCabin::RPC::ClientRPC::getErrorMessage ( ) const

If an RPC failure occurred, return a message describing that error.

All errors indicate that it is unknown whether or not the server executed the RPC. Unless the RPC was canceled with cancel(), the ClientSession has been disconnected and is no longer useful for initiating new RPCs.