some new exmple

chapter_10/usr.hrl

@@ -0,0 +1,8 @@
+%%% File: usr.hrl
+%%% Description: Include file for user db
+
+-record(usr, {msisdn,
+              id,
+              status = enabled,
+              plan,
+              services = []}).

chapter_10/usr_db.erl

@@ -0,0 +1,72 @@
+%%% File: usr_db.erl
+%%% Description: Database API for subscriber DB
+
+-module(usr_db).
+-include("usr.hrl").
+-export([create_tables/1, close_tables/0]).
+-export([add_usr/1, update_usr/1]).
+-export([lookup_id/1, lookup_msisdn/1]).
+-export([restore_backup/0]).
+
+create_tables(FileName) ->
+  ets:new(usrRam, [named_table, {keypos, #usr.msisdn}]),
+  ets:new(usrIndex, [named_table]),
+  dets:open_file(usrDisk, [{file, FileName}, {keypos, #usr.msisdn}]).
+
+close_tables() ->
+  ets:delete(usrRam),
+  ets:delete(usrIndex),
+  dets:close(usrDisk).
+
+add_usr(#usr{msisdn=PhoneNo, id=CustId} = Usr) ->
+  ets:insert(usrIndex, {CustId, PhoneNo}),
+  update_usr(Usr).
+
+update_usr(Usr) ->
+  ets:insert(usrRam, Usr),
+  dets:insert(usrDisk, Usr),
+  ok.
+
+lookup_id(CustId) ->
+  case get_index(CustId) of
+    {ok, PhoneNo} -> lookup_msisdn(PhoneNo);
+    {error, instance} -> {error, instance}
+  end.
+
+lookup_msisdn(PhoneNo) ->
+  case ets:lookup(usrRam, PhoneNo) of
+    [Usr] -> {ok, Usr};
+    [] -> {error, instance}
+  end.
+
+get_index(CustId) ->
+  case ets:lookup(usrIndex, CustId) of
+    [{CustId, PhoneNo}] -> {ok, PhoneNo};
+    [] -> {error, instance}
+  end.
+
+restore_backup() ->
+  Insert = fun(#usr{msisdn=PhoneNo, id=Id} = Usr) ->
+             ets:insert(usrRam, Usr),
+             ets:insert(usrIndex, {Id, PhoneNo}),
+             continue
+           end,
+  dets:traverse(usrDisk, Insert).
+
+delete_disabled() ->
+  ets:safe_fixtable(usrRam, true),
+  catch loop_delete_disabled(ets:first(usrRam)),
+  ets:safe_fixtable(usrRam, false),
+  ok.
+
+loop_delete_disabled('$end_of_table') ->
+  ok;
+
+loop_delete_disabled(PhoneNo) ->
+  case ets:lookup(usrRam, PhoneNo) of
+    [usr{status=disabled, id=CustId}] ->
+      delete_usr(PhoneNo, CustId);
+    _ ->
+      ok
+  end,
+  loop_delete_disabled(ets:next(usrRam, PhoneNo)).

chapter_11/dist.erl

@@ -0,0 +1,5 @@
+-module(dist).
+-export([t/1]).
+
+t(From) ->
+  From ! node().