[erlang-questions] Shared ETS Access

Steve Vinoski <>
Sun Jan 10 23:30:30 CET 2010


On Sun, Jan 10, 2010 at 4:57 PM, L. S. <> wrote:

> Where can I find a full, simple example of one Erlang process creating an
> ETS table and having another process access that table?
>
> After looking at the docs, I seem to understand the basic call to create
> and populate a table...
>
>    %ErlShellProcess1:
>        TabId = ets:new(food, [public, named_table]).
>        ets:insert(TabId, {drink, cofee}).
>
>
> ... (And I know I may have to use gen_server to create a persistent
> process) but I don't know the mechanics to make the it work.
>
>    %ErlShellProcess2:
>        ?
>

-module(ets_ex).
-export([run/0]).

run() ->
    Parent = self(),
    spawn(fun() ->
                  TblName = my_table,
                  Tbl = ets:new(TblName, [public, named_table]),
                  Parent ! {ready, self(), TblName},
                  receive
                      stop ->
                          ets:delete(Tbl)
                  end
          end),
    receive
        {ready, Loop, TblNm} ->
            ets:insert(TblNm, {"key", "value"}),
            Lookup = ets:lookup(TblNm, "key"),
            io:format("lookup returned ~p~n", [Lookup]),
            Loop ! stop
    end.

The spawned anonymous function creates and owns the ets table, and for this
example serves essentially the same purpose as a gen_server and its receive
loop would. The run() function spawns the loop, waits for the message
telling it the table name, then does an insert and a lookup on the table.
Note that all the main part of the run() function knows is the name of the
table received in the message from the loop.

--steve


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