Remove ElasticManager field printing_kwargs

The name of the field is confusing. It's much cleaner for the users to call
`get_connect_cmd` directly. Workers may be added in different ways to the same
ElasticManager and require a different startup. Also, `get_connect_cmd` was not
using printing_kwargs for it's kwargs by default, which was inconsistent.

Author: oschulz

README.md

@@ -19,7 +19,7 @@ port and publish their own host/port information for other workers to connect to
 On the master, you need to instantiate an instance of `ElasticManager`. The constructors defined are:
 
 ```julia
-ElasticManager(;addr=IPv4("127.0.0.1"), port=9009, cookie=nothing, topology=:all_to_all, printing_kwargs=())
+ElasticManager(;addr=IPv4("127.0.0.1"), port=9009, cookie=nothing, topology=:all_to_all)
 ElasticManager(port) = ElasticManager(;port=port)
 ElasticManager(addr, port) = ElasticManager(;addr=addr, port=port)
 ElasticManager(addr, port, cookie) = ElasticManager(;addr=addr, port=port, cookie=cookie)
@@ -37,6 +37,17 @@ ElasticManager:
     /home/user/bin/julia --project=/home/user/myproject/Project.toml -e 'using ElasticClusterManager; ElasticClusterManager.elastic_worker("4cOSyaYpgSl6BC0C","127.0.1.1",36275)'
 ```
 
-By default, the printed command uses the absolute path to the current Julia executable and activates the same project as the current session. You can change either of these defaults by passing `printing_kwargs=(absolute_exename=false, same_project=false))` to the first form of the `ElasticManager` constructor.
+Use `ElasticClusterManager.get_connect_cmd(em; kwargs...)` to generate a suitable system command to start up a
+worker process, e.g.:
 
-Once workers are connected, you can print the `em` object again to see them added to the list of active workers.
+```julia
+print(ElasticClusterManager.get_connect_cmd(em; absolute_exename=false, same_project=false))
+```
+
+```
+/home/user/bin/julia --project=/home/user/myproject/Project.toml -e 'using ElasticClusterManager; ElasticClusterManager.elastic_worker("4cOSyaYpgSl6BC0C","127.0.1.1",36275)'
+```
+
+By default, the printed command uses the absolute path to the current Julia executable and activates the same project as the current session.
+
+Once workers have connected, `show(em)` should show them added to the list of active workers.

src/elastic.jl

@@ -21,12 +21,18 @@ Constructor:
 ```julia
 function ElasticManager(;
     addr=IPv4("127.0.0.1"), port=9009, cookie=nothing,
-    topology=:all_to_all, manage_callback=elastic_no_op_callback, printing_kwargs=()
+    topology=:all_to_all, manage_callback=elastic_no_op_callback
 )
 ```
 
 The manager will listen for worker connections on `addr:port`. Workers have
 to authenticate themselves with `cookie` (randomly generated by default).
+`topology` sets the Julia cluster topology and may be `:all_to_all` or
+`:master_worker` (see documentation of `Distributed.addprocs` for details.
+
+Workers are not added via `Distributed.addprocs`, instead started via
+[`ElasticClusterManager.elastic_worker`](@ref) from external Julia
+processes, this is up to the user.
 
 If `manage_callback` is set to a user-provided `my_manage_callback`, it will
 be called on the primary Julia process when `Distributed.manage` adds or
@@ -47,11 +53,10 @@ struct ElasticManager <: Distributed.ClusterManager
     topology::Symbol
     sockname
     manage_callback
-    printing_kwargs
 
     function ElasticManager(;
-        addr=IPv4("127.0.0.1"), port=9009, cookie=nothing,
-        topology=:all_to_all, manage_callback=elastic_no_op_callback, printing_kwargs=()
+        addr=Sockets.IPv4("127.0.0.1"), port=9009, cookie=nothing,
+        topology=:all_to_all, manage_callback=elastic_no_op_callback
     )
         Distributed.init_multi()
         cookie !== nothing && Distributed.cluster_cookie(cookie)
@@ -67,7 +72,7 @@ struct ElasticManager <: Distributed.ClusterManager
 
         l_sock = Distributed.listen(addr, port)
 
-        lman = new(Dict{Int, Distributed.WorkerConfig}(), Channel{Sockets.TCPSocket}(typemax(Int)), Set{Int}(), topology, Sockets.getsockname(l_sock), manage_callback, printing_kwargs)
+        lman = new(Dict{Int, Distributed.WorkerConfig}(), Channel{Sockets.TCPSocket}(typemax(Int)), Set{Int}(), topology, Sockets.getsockname(l_sock), manage_callback)
 
         t1 = @async begin
             while true
@@ -171,9 +176,6 @@ function Base.show(io::IO, mgr::ElasticManager)
     seek(iob, position(iob)-1)
     println(iob, "]")
 
-    println(iob, "  Worker connect command : ")
-    print(iob, "    ", get_connect_cmd(mgr; mgr.printing_kwargs...))
-
     print(io, String(take!(iob)))
 end
 
@@ -207,6 +209,16 @@ function elastic_worker(
     Distributed.start_worker(c, cookie)
 end
 
+"""
+    ElasticManager.get_connect_cmd(em::ElasticManager; absolute_exename=true, same_project=true, exeflags::Tuple=())
+
+Return a suitable system command that starts a Julia process with an elastic
+worker that will try to connect the the primary Julia process running the
+[`ElasticManager`](@ref) instance `em`.
+
+The output of `get_connect_cmd` should be taken as a baseline. Complex use
+cases (on some batch systems, etc.) may require a more involved command.
+"""
 function get_connect_cmd(em::ElasticManager; absolute_exename=true, same_project=true, exeflags::Tuple=())
     ip = string(em.sockname[1])
     port = convert(Int,em.sockname[2])
@@ -220,5 +232,4 @@ function get_connect_cmd(em::ElasticManager; absolute_exename=true, same_project
         project...,
         "-e 'import ElasticClusterManager; ElasticClusterManager.elastic_worker(\"$cookie\",\"$ip\",$port)'"
     ]," ")
-
 end

test/elastic.jl

@@ -25,7 +25,6 @@
         @test lines[2] == "Active workers : []"
         @test lines[3] == "Number of workers to be added  : 0"
         @test lines[4] == "Terminated workers : [ 2]"
-        @test lines[5] == "Worker connect command :"
     end
 
     @testset "Other constructors for ElasticManager()" begin