riak_test/intercepts/riak_kv_worker_intercepts.erl

-module(riak_kv_worker_intercepts).
-compile(export_all).
-include("intercept.hrl").
-define(M, riak_kv_worker_orig).

%
% Okay, this is an interesting intercept.  The intention here is to insert some
% code into the point where the vnode has completed its fold, but before it invokes the finish
% command, which will inform the riak_core_vnode that handoff has completed for this node.
% This is a magic time, when handoff is running, and the fold has completed.
% In this case, we send a message to a process that is running in riak test
% (see verify_handoff_write_once, for an example), which will do a write during this
% magic time.  We wait for said process to return us an ok.
%
% The objective is to force the vnode to trigger a handle_handoff_command,
% thus exercising the runtime/forwarding handoff logic in the vnode.
%
handle_work_intercept({fold, FoldFun, FinishFun}, Sender, State) ->
    FinishWrapperFun = fun(X) ->
        catch global:send(rt_ho_w1c_proc, {write, self()}),
        receive
            ok -> ok
        end,
        FinishFun(X)
    end,
    ?M:handle_work_orig({fold, FoldFun, FinishWrapperFun}, Sender, State).