From 81bdbed444df2cbcf3cdb32f7d4a74019de06454 Mon Sep 17 00:00:00 2001
From: Adam Kocoloski <adam@cloudant.com>
Date: Wed, 11 Aug 2010 15:22:33 -0400
Subject: reorganize couch .erl and driver code into rebar layout

---
 apps/couch/src/couch_log.erl | 151 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 apps/couch/src/couch_log.erl

(limited to 'apps/couch/src/couch_log.erl')

diff --git a/apps/couch/src/couch_log.erl b/apps/couch/src/couch_log.erl
new file mode 100644
index 00000000..2d62cbb5
--- /dev/null
+++ b/apps/couch/src/couch_log.erl
@@ -0,0 +1,151 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_log).
+-behaviour(gen_event).
+
+-export([start_link/0,stop/0]).
+-export([debug_on/0,info_on/0,get_level/0,get_level_integer/0, set_level/1]).
+-export([init/1, handle_event/2, terminate/2, code_change/3, handle_info/2, handle_call/2]).
+-export([read/2]).
+
+-define(LEVEL_ERROR, 3).
+-define(LEVEL_INFO, 2).
+-define(LEVEL_DEBUG, 1).
+-define(LEVEL_TMI, 0).
+
+level_integer(error)    -> ?LEVEL_ERROR;
+level_integer(info)     -> ?LEVEL_INFO;
+level_integer(debug)    -> ?LEVEL_DEBUG;
+level_integer(tmi)      -> ?LEVEL_TMI;
+level_integer(_Else)    -> ?LEVEL_ERROR. % anything else default to ERROR level
+
+level_atom(?LEVEL_ERROR) -> error;
+level_atom(?LEVEL_INFO) -> info;
+level_atom(?LEVEL_DEBUG) -> debug;
+level_atom(?LEVEL_TMI) -> tmi.
+
+
+start_link() ->
+    couch_event_sup:start_link({local, couch_log}, error_logger, couch_log, []).
+
+stop() ->
+    couch_event_sup:stop(couch_log).
+
+init([]) ->
+    % read config and register for configuration changes
+
+    % just stop if one of the config settings change. couch_server_sup
+    % will restart us and then we will pick up the new settings.
+    ok = couch_config:register(
+        fun("log", "file") ->
+            ?MODULE:stop();
+        ("log", "level") ->
+            ?MODULE:stop();
+        ("log", "include_sasl") ->
+            ?MODULE:stop()
+        end),
+
+    Filename = couch_config:get("log", "file", "couchdb.log"),
+    Level = level_integer(list_to_atom(couch_config:get("log", "level", "info"))),
+    Sasl = list_to_atom(couch_config:get("log", "include_sasl", "true")),
+
+    case ets:info(?MODULE) of
+    undefined -> ets:new(?MODULE, [named_table]);
+    _ -> ok
+    end,
+    ets:insert(?MODULE, {level, Level}),
+
+    {ok, Fd} = file:open(Filename, [append]),
+    {ok, {Fd, Level, Sasl}}.
+
+debug_on() ->
+    get_level_integer() =< ?LEVEL_DEBUG.
+
+info_on() ->
+    get_level_integer() =< ?LEVEL_INFO.
+
+set_level(LevelAtom) ->
+    set_level_integer(level_integer(LevelAtom)).
+
+get_level() ->
+    level_atom(get_level_integer()).
+
+get_level_integer() ->
+    try
+        ets:lookup_element(?MODULE, level, 2)
+    catch error:badarg ->
+        ?LEVEL_ERROR
+    end.
+
+set_level_integer(Int) ->
+    gen_event:call(error_logger, couch_log, {set_level_integer, Int}).
+
+handle_event({Pid, couch_error, {Format, Args}}, {Fd, _LogLevel, _Sasl}=State) ->
+    log(Fd, Pid, error, Format, Args),
+    {ok, State};
+handle_event({Pid, couch_info, {Format, Args}}, {Fd, LogLevel, _Sasl}=State)
+when LogLevel =< ?LEVEL_INFO ->
+    log(Fd, Pid, info, Format, Args),
+    {ok, State};
+handle_event({Pid, couch_debug, {Format, Args}}, {Fd, LogLevel, _Sasl}=State)
+when LogLevel =< ?LEVEL_DEBUG ->
+    log(Fd, Pid, debug, Format, Args),
+    {ok, State};
+handle_event({error_report, _, {Pid, _, _}}=Event, {Fd, _LogLevel, Sasl}=State)
+when Sasl =/= false ->
+    log(Fd, Pid, error, "~p", [Event]),
+    {ok, State};
+handle_event({error, _, {Pid, Format, Args}}, {Fd, _LogLevel, Sasl}=State)
+when Sasl =/= false ->
+    log(Fd, Pid, error, Format, Args),
+    {ok, State};
+handle_event({_, _, {Pid, _, _}}=Event, {Fd, LogLevel, _Sasl}=State)
+when LogLevel =< ?LEVEL_TMI ->
+    % log every remaining event if tmi!
+    log(Fd, Pid, tmi, "~p", [Event]),
+    {ok, State};
+handle_event(_Event, State) ->
+    {ok, State}.
+
+handle_call({set_level_integer, NewLevel}, {Fd, _LogLevel, Sasl}) ->
+    ets:insert(?MODULE, {level, NewLevel}),
+    {ok, ok, {Fd, NewLevel, Sasl}}.
+
+handle_info(_Info, State) ->
+    {ok, State}.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+terminate(_Arg, {Fd, _LoggingLevel, _Sasl}) ->
+    file:close(Fd).
+
+log(Fd, Pid, Level, Format, Args) ->
+    Msg = io_lib:format(Format, Args),
+    ok = io:format("[~s] [~p] ~s~n", [Level, Pid, Msg]), % dump to console too
+    Msg2 = re:replace(lists:flatten(Msg),"\\r\\n|\\r|\\n", "\r\n",
+        [global, {return, list}]),
+    ok = io:format(Fd, "[~s] [~s] [~p] ~s\r~n\r~n", [httpd_util:rfc1123_date(), Level, Pid, Msg2]).
+
+read(Bytes, Offset) ->
+    LogFileName = couch_config:get("log", "file"),
+    LogFileSize = couch_util:file_read_size(LogFileName),
+
+    {ok, Fd} = file:open(LogFileName, [read]),
+    Start = lists:max([LogFileSize - Bytes, 0]) + Offset,
+
+    % TODO: truncate chopped first line
+    % TODO: make streaming
+
+    {ok, Chunk} = file:pread(Fd, Start, LogFileSize),
+    Chunk.
-- 
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