From 37a16d1924778cddb65aa6862d752c2fe6d989ec Mon Sep 17 00:00:00 2001
From: Fabio Salvini <salvini.fabio001@gmail.com>
Date: Mon, 12 Jun 2017 11:35:57 +0200
Subject: [PATCH] Save log configs to DETS

---
 apps/log_monitor/src/config.erl   | 27 +++++++++++++++++-------
 apps/log_monitor/src/gatherer.erl | 34 +++++++++++++++++--------------
 config/sys.config                 |  1 +
 3 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/apps/log_monitor/src/config.erl b/apps/log_monitor/src/config.erl
index c9caa0e..41dce6e 100644
--- a/apps/log_monitor/src/config.erl
+++ b/apps/log_monitor/src/config.erl
@@ -6,22 +6,35 @@
 -export([handle_info/2, handle_cast/2, handle_call/3]).
 -export([code_change/3]).
 
+-define(INTERVAL, 60000). % One minute
+
 start_link() ->
     gen_server:start_link(?MODULE, [], []).
 
 init([]) ->
     register(config, self()),
-    {ok, []}.
+    {ok, Storage} = application:get_env(log_monitor, storage),
+    {ok, Logfiles} = dets:open_file(Storage, []),
+    %% erlang:send_after(?INTERVAL, self(), trigger),
+    {ok, [Logfiles]}.
 
+handle_info(trigger, State) ->
+    erlang:send_after(?INTERVAL, self(), trigger),
+    {noreply, State};
 handle_info(_Msg, State) ->
     {noreply, State}.
 
 handle_cast(_Msg, State) ->
     {noreply, State}.
 
-handle_call({monitor, Path}, _From, State) ->
-    supervisor:start_child(logfiles_sup, [Path]),
-    {reply, ok, State}.
+handle_call({monitor, File}, _From, [Logfiles]) ->
+    case dets:lookup(Logfiles, File) of
+        [] ->
+            dets:insert(Logfiles, {File, "ERROR"}),
+            supervisor:start_child(logfiles_sup, [File]),
+            {reply, ok, [Logfiles]};
+        _ -> {reply, duplicate, [Logfiles]}
+    end.
 
 terminate(_Reason, _State) ->
     shutdown.
@@ -29,6 +42,6 @@ terminate(_Reason, _State) ->
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-monitor_log(Path) ->
-    config ! {monitor, Path},
-    gen_server:call(config, {monitor, Path}).
+monitor_log(File) ->
+    config ! {monitor, File},
+    gen_server:call(config, {monitor, File}).
diff --git a/apps/log_monitor/src/gatherer.erl b/apps/log_monitor/src/gatherer.erl
index c52210f..2273cd6 100644
--- a/apps/log_monitor/src/gatherer.erl
+++ b/apps/log_monitor/src/gatherer.erl
@@ -5,31 +5,35 @@
 -export([handle_info/2, handle_cast/2, handle_call/3]).
 -export([code_change/3]).
 
+-record(log, {file, error_regex}).
+
+%% start_link(File, ErrorRegex) ->
 start_link(File) ->
-    gen_server:start_link(?MODULE, [File], []).
+    ErrorRegex = "ERROR",
+    gen_server:start_link(?MODULE, [#log{file = File, error_regex = ErrorRegex}], []).
 
-init([File]) ->
-    {ok, [off, File]}.
+init([Log]) ->
+    {ok, [off, Log]}.
 
-handle_info({log_line, Text}, [off, File]) ->
-    case isError(Text) of
+handle_info({log_line, Text}, [off, Log = #log{error_regex = ErrorRegex}]) ->
+    case isError(Text, ErrorRegex) of
         true ->
             {ok, Timer} = timer:send_after(1000, {timeout}),
-            {noreply, [on, File, Text, Timer]};
-        false -> {noreply, [off, File]}
+            {noreply, [on, Log, Text, Timer]};
+        false -> {noreply, [off, Log]}
     end;
-handle_info({log_line, Text}, [on, File, Error, Timer]) ->
-    case isError(Text) of
+handle_info({log_line, Text}, [on, Log = #log{error_regex = ErrorRegex}, Error, Timer]) ->
+    case isError(Text, ErrorRegex) of
         true ->
             timer:clean(Timer),
             {ok, NewTimer} = timer:send_after(1000, {timeout}),
-            {noreply, [on, File, Error ++ "\n" ++ Text, NewTimer]};
+            {noreply, [on, Log, Error ++ "\n" ++ Text, NewTimer]};
         false ->
-            {noreply, [on, File, Error ++ "\n" ++ Text, Timer]}
+            {noreply, [on, Log, Error ++ "\n" ++ Text, Timer]}
     end;
-handle_info({timeout}, [on, File, Error, _Timer]) ->
+handle_info({timeout}, [on, Log = #log{file = File}, Error, _Timer]) ->
     mailer ! {error, File, Error},
-    {noreply, [off, File]}.
+    {noreply, [off, Log]}.
 
 handle_cast(_Msg, State) ->
     {noreply, State}.
@@ -43,8 +47,8 @@ terminate(_Reason, _State) ->
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-isError(Text) ->
-    case re:run(Text, "ERROR") of %% TODO
+isError(Text, ErrorRegex) ->
+    case re:run(Text, ErrorRegex) of
         {match, _} ->
             true;
         nomatch ->
diff --git a/config/sys.config b/config/sys.config
index eb7bcfa..967c843 100644
--- a/config/sys.config
+++ b/config/sys.config
@@ -1,6 +1,7 @@
 [
   { log_monitor, 
     [
+      {storage, "/tmp/logfiles"},
       {email_config,
         [
           {sender, "me@example.com"},