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

#include <OpaqueClientRPC.h>

Public Types
enum	Status { NOT_READY, OK, ERROR, CANCELED }
	State of the RPC. More...
typedef Core::Time::SteadyClock	Clock
	Clock used for timeouts.
typedef Clock::time_point	TimePoint
	Type for absolute time values used for timeouts.
Public Member Functions
	OpaqueClientRPC ()
	Default constructor.
	OpaqueClientRPC (OpaqueClientRPC &&)
	Move constructor.
	~OpaqueClientRPC ()
	Destructor.
OpaqueClientRPC &	operator= (OpaqueClientRPC &&)
	Move assignment.
void	cancel ()
	Abort the RPC.
std::string	getErrorMessage () const
	If an error has occurred, return a message describing that error.
Status	getStatus () const
	See Status.
Core::Buffer *	peekReply ()
	Look at the reply buffer.
void	waitForReply (TimePoint timeout)
	Block until the reply is ready, an error has occurred, or the given timeout elapses.
Private Member Functions
void	update ()
	Update the fields of this object if the RPC has not completed.
	OpaqueClientRPC (const OpaqueClientRPC &)
OpaqueClientRPC &	operator= (const OpaqueClientRPC &)
Private Attributes
std::mutex	mutex
	Protects all the members of this class.
std::shared_ptr< ClientSession >	session
	The session on which this RPC is executing.
uint64_t	responseToken
	A token given to the session to look up new information about the progress of this RPC's reply.
Status	status
	See Status.
Core::Buffer	reply
	The payload of a successful reply, once available.
std::string	errorMessage
	If an error occurred in the RPC then this holds the error message; otherwise, this is the empty string.
Friends
class	ClientSession

Detailed Description

This class represents an asynchronous remote procedure call.

A ClientSession returns an instance when an RPC is initiated; this can be used to wait for and retrieve the reply.

Definition at line 39 of file OpaqueClientRPC.h.

Member Typedef Documentation

typedef Core::Time::SteadyClock LogCabin::RPC::OpaqueClientRPC::Clock

Clock used for timeouts.

Definition at line 42 of file OpaqueClientRPC.h.

typedef Clock::time_point LogCabin::RPC::OpaqueClientRPC::TimePoint

Type for absolute time values used for timeouts.

Definition at line 44 of file OpaqueClientRPC.h.

Member Enumeration Documentation

enum LogCabin::RPC::OpaqueClientRPC::Status

State of the RPC.

Enumerator:

NOT_READY	The RPC is still in progress.
OK	The RPC has completed successfully.
ERROR	The RPC has failed with an error (see getErrorMessage()).
CANCELED	The RPC was aborted using cancel().

Definition at line 49 of file OpaqueClientRPC.h.

Constructor & Destructor Documentation

LogCabin::RPC::OpaqueClientRPC::OpaqueClientRPC ( )

Default constructor.

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

Definition at line 24 of file OpaqueClientRPC.cc.

LogCabin::RPC::OpaqueClientRPC::OpaqueClientRPC ( OpaqueClientRPC && other )

Move constructor.

Definition at line 34 of file OpaqueClientRPC.cc.

LogCabin::RPC::OpaqueClientRPC::~OpaqueClientRPC ( )

Destructor.

Definition at line 44 of file OpaqueClientRPC.cc.

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

Member Function Documentation

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

Move assignment.

Definition at line 50 of file OpaqueClientRPC.cc.

void LogCabin::RPC::OpaqueClientRPC::cancel ( )

Abort the RPC.

The caller is no longer interested in its reply.

Definition at line 62 of file OpaqueClientRPC.cc.

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

If an error has 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.

Returns:: If an error has occurred, a message describing that error. Otherwise, an empty string.

Definition at line 76 of file OpaqueClientRPC.cc.

OpaqueClientRPC::Status LogCabin::RPC::OpaqueClientRPC::getStatus ( ) const

See Status.

Definition at line 84 of file OpaqueClientRPC.cc.

Core::Buffer * LogCabin::RPC::OpaqueClientRPC::peekReply ( )

Look at the reply buffer.

Returns:: If the reply is already available and there were no errors, returns a pointer to the reply buffer inside this OpaqueClientRPC object. Otherwise, returns NULL.

Definition at line 92 of file OpaqueClientRPC.cc.

void LogCabin::RPC::OpaqueClientRPC::waitForReply ( TimePoint timeout )

Block until the reply is ready, an error has occurred, or the given timeout elapses.

This may be used from worker threads only, because OpaqueClientRPC objects rely on the event loop servicing their ClientSession in order to make progress.

Parameters:

timeout After this time has elapsed, stop waiting and return. The RPC's results will probably not be available yet in this case (status will be NOT_READY).

Definition at line 103 of file OpaqueClientRPC.cc.

void LogCabin::RPC::OpaqueClientRPC::update ( ) [private]

Update the fields of this object if the RPC has not completed.

Must be called with the lock held.

Definition at line 124 of file OpaqueClientRPC.cc.

OpaqueClientRPC& LogCabin::RPC::OpaqueClientRPC::operator= ( const OpaqueClientRPC & ) [private]