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classdef Future < IceInternal.WrapperObject
% Future Summary of Future
%
% Represents an asynchronous invocation.
%
% Future Methods:
% wait - Block until the invocation reaches a certain state, or a
% timeout expires.
% fetchOutputs - Block until the invocation completes and then return
% the results or raise an exception.
% cancel - If the invocation is still pending, calling this method
% instructs the local Ice run time to ignore its results.
%
% Future Properties:
% ID - A unique identifier for this object.
% NumOutputArguments - The number of output arguments that will be
% returned by fetchOutputs upon successful completion.
% Operation - The name of the operation that was invoked.
% Read - True if fetchOutputs has already been called.
% State - The current state of the future.
% Copyright (c) ZeroC, Inc. All rights reserved.
properties(SetAccess=private)
% ID - A unique identifier for this object.
ID int32 = 0
% NumOutputArguments - The number of output arguments that will be
% returned by fetchOutputs upon successful completion.
NumOutputArguments int32
% Operation - The name of the operation that was invoked.
Operation char
% Read - True if fetchOutputs has already been called.
Read logical = false
% State - The current state of the future. Its initial value is
% 'running' and its final value is 'finished'. A remote invocation
% transitions from 'running' to 'sent' to 'finished'.
State char = 'running'
end
methods
function obj = Future(impl, op, numOutArgs, type, fetchFunc)
%
% The nextId variable is persistent, which acts somewhat like a static variable. It retains its
% current value as long as there is at least one reference to a Future instance. Once the last
% reference drops, nextId is cleared.
%
persistent nextId;
obj = obj@IceInternal.WrapperObject(impl, type);
obj.Operation = op;
obj.NumOutputArguments = numOutArgs;
obj.fetchFunc = fetchFunc;
if nextId
obj.ID = nextId;
else
nextId = int32(0);
obj.ID = 0;
end
nextId = nextId + 1;
end
function delete(obj)
if ~isempty(obj.impl_)
obj.iceCall('unref');
end
obj.impl_ = [];
end
function ok = wait(obj, state, timeout)
% wait - Block until the invocation reaches a certain state, or a
% timeout expires.
%
% Parameters:
% state (char) - If provided, wait blocks until the future reaches
% the given state. Must be one of 'running', 'sent', 'finished'.
% If not provided, wait blocks until the state is 'finished'.
% Note that the future enters the 'finished' state when
% completed successfully or exceptionally.
% timeout (double) - If provided, wait blocks up to the given
% number of seconds while waiting for the future to reach the
% desired state. If the timeout is negative or not provided,
% wait blocks indefinitely.
%
% Returns (logical) - True if the future reached the desired state,
% false if the future has not reached the desired state or an
% exception occurred.
if ~isempty(obj.impl_)
if nargin == 1
ok = obj.iceCallWithResult('wait');
elseif nargin == 2
ok = obj.iceCallWithResult('waitState', state, -1);
else
ok = obj.iceCallWithResult('waitState', state, timeout);
end
else
ok = true;
end
end
function varargout = fetchOutputs(obj)
% fetchOutputs Block until the invocation completes and then
% return the results or raise an exception. Can only be called
% once.
if obj.Read
throw(MException('Ice:InvalidStateException', 'outputs already read'));
end
if ~isempty(obj.fetchFunc)
%
% We assume the fetch function implementation also deletes the C++ object so that we
% can avoid another call into C++.
%
try
[varargout{1:obj.NumOutputArguments}] = obj.fetchFunc(obj);
obj.impl_ = [];
catch ex
obj.impl_ = [];
rethrow(ex);
end
end
obj.Read = true;
end
function cancel(obj)
% cancel If the invocation is still pending, calling this method
% instructs the local Ice run time to ignore its results.
if ~isempty(obj.impl_)
obj.iceCall('cancel');
end
end
function r = get.State(obj)
if ~isempty(obj.impl_)
obj.State = obj.iceCallWithResult('state');
r = obj.State;
else
r = 'finished';
end
end
end
properties(Access=private)
fetchFunc
end
end
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