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%% Copyright (c) 2011-2012 Basho Technologies, Inc. All Rights Reserved.
%%
%% This file is provided to you 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
%%
%% https://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.
%% @doc Helper functions for webmachine's default log handlers
-module(webmachine_log).
-include("webmachine_logger.hrl").
-export([add_handler/2,
call/2,
call/3,
datehour/0,
datehour/1,
defer_refresh/1,
delete_handler/1,
fix_log/2,
fmt_ip/1,
fmtnow/0,
log_access/1,
log_close/3,
log_open/1,
log_open/2,
log_write/2,
maybe_rotate/3,
month/1,
refresh/2,
suffix/1,
zeropad/2,
zone/0]).
-record(state, {hourstamp :: non_neg_integer(),
filename :: string(),
handle :: file:io_device()}).
%% @doc Add a handler to receive log events
-type add_handler_result() :: ok | {'EXIT', term()} | term().
-spec add_handler(atom() | {atom(), term()}, term()) -> add_handler_result().
add_handler(Mod, Args) ->
gen_event:add_handler(?EVENT_LOGGER, Mod, Args).
%% @doc Make a synchronous call directly to a specific event handler
%% module
-type error() :: {error, bad_module} | {'EXIT', term()} | term().
-spec call(atom(), term()) -> term() | error().
call(Mod, Msg) ->
gen_event:call(?EVENT_LOGGER, Mod, Msg).
%% @doc Make a synchronous call directly to a specific event handler
%% module
-spec call(atom(), term(), timeout()) -> term() | error().
call(Mod, Msg, Timeout) ->
gen_event:call(?EVENT_LOGGER, Mod, Msg, Timeout).
%% @doc Return a four-tuple containing year, month, day, and hour
%% of the current time.
-type datehour() :: {calendar:year(), calendar:month(), calendar:day(), calendar:hour()}.
-spec datehour() -> datehour().
datehour() ->
datehour(os:timestamp()).
%% @doc Return a four-tuple containing year, month, day, and hour
%% of the specified time.
-spec datehour(erlang:timestamp()) -> datehour().
datehour(TS) ->
{{Y, M, D}, {H, _, _}} = calendar:now_to_universal_time(TS),
{Y, M, D, H}.
%% @doc Defer the refresh of a log file.
-spec defer_refresh(atom()) -> {ok, timer:tref()} | {error, term()}.
defer_refresh(Mod) ->
{_, {_, M, S}} = calendar:universal_time(),
Time = 1000 * (3600 - ((M * 60) + S)),
timer:apply_after(Time, ?MODULE, refresh, [Mod, os:timestamp()]).
%% @doc Remove a log handler
-type delete_handler_result() :: term() | {error, module_not_found} | {'EXIT', term()}.
-spec delete_handler(atom() | {atom(), term()}) -> delete_handler_result().
delete_handler(Mod) ->
gen_event:delete_handler(?EVENT_LOGGER, Mod, []).
%% Seek backwards to the last valid log entry
-spec fix_log(file:io_device(), non_neg_integer()) -> ok.
fix_log(_FD, 0) ->
ok;
fix_log(FD, 1) ->
{ok, 0} = file:position(FD, 0),
ok;
fix_log(FD, Location) ->
case file:pread(FD, Location - 1, 1) of
{ok, [$\n | _]} ->
ok;
{ok, _} ->
fix_log(FD, Location - 1)
end.
%% @doc Format an IP address or host name
-spec fmt_ip(undefined | string() | inet:ip4_address() | inet:ip6_address()) -> string().
fmt_ip(IP) when is_tuple(IP) ->
inet_parse:ntoa(IP);
fmt_ip(undefined) ->
"0.0.0.0";
fmt_ip(HostName) ->
HostName.
%% @doc Format the current time into a string
-spec fmtnow() -> string().
fmtnow() ->
{{Year, Month, Date}, {Hour, Min, Sec}} = calendar:local_time(),
io_lib:format("[~2..0w/~s/~4..0w:~2..0w:~2..0w:~2..0w ~s]",
[Date,month(Month),Year, Hour, Min, Sec, zone()]).
%% @doc Notify registered log event handler of an access event.
-spec log_access(tuple()) -> ok.
log_access({_, _, _}=LogData) ->
gen_event:sync_notify(?EVENT_LOGGER, {log_access, LogData}).
%% @doc Close a log file.
-spec log_close(atom(), string(), file:io_device()) -> ok | {error, term()}.
log_close(Mod, Name, FD) ->
error_logger:info_msg("~p: closing log file: ~p~n", [Mod, Name]),
file:close(FD).
%% @doc Open a new log file for writing
-spec log_open(string()) -> {file:io_device(), non_neg_integer()}.
log_open(FileName) ->
DateHour = datehour(),
{log_open(FileName, DateHour), DateHour}.
%% @doc Open a new log file for writing
-spec log_open(string(), non_neg_integer()) -> file:io_device().
log_open(FileName, DateHour) ->
LogName = FileName ++ suffix(DateHour),
error_logger:info_msg("opening log file: ~p~n", [LogName]),
filelib:ensure_dir(LogName),
{ok, FD} = file:open(LogName, [read, write, raw]),
{ok, Location} = file:position(FD, eof),
fix_log(FD, Location),
file:truncate(FD),
FD.
-spec log_write(file:io_device(), iolist()) -> ok | {error, term()}.
log_write(FD, IoData) ->
file:write(FD, lists:flatten(IoData)).
%% @doc Rotate a log file if the hour it represents
%% has passed.
-spec maybe_rotate(atom(), erlang:timestamp(), #state{}) -> #state{}.
maybe_rotate(Mod, Time, State) ->
ThisHour = datehour(Time),
if ThisHour == State#state.hourstamp ->
State;
true ->
defer_refresh(Mod),
log_close(Mod, State#state.filename, State#state.handle),
Handle = log_open(State#state.filename, ThisHour),
State#state{hourstamp=ThisHour, handle=Handle}
end.
%% @doc Convert numeric month value to the abbreviation
-spec month(1..12) -> string().
month(1) ->
"Jan";
month(2) ->
"Feb";
month(3) ->
"Mar";
month(4) ->
"Apr";
month(5) ->
"May";
month(6) ->
"Jun";
month(7) ->
"Jul";
month(8) ->
"Aug";
month(9) ->
"Sep";
month(10) ->
"Oct";
month(11) ->
"Nov";
month(12) ->
"Dec".
%% @doc Make a synchronous call to instruct a log handler to refresh
%% itself.
-spec refresh(atom(), erlang:timestamp()) -> ok | {error, term()}.
refresh(Mod, Time) ->
call(Mod, {refresh, Time}, infinity).
-spec suffix(datehour()) -> string().
suffix({Y, M, D, H}) ->
YS = zeropad(Y, 4),
MS = zeropad(M, 2),
DS = zeropad(D, 2),
HS = zeropad(H, 2),
lists:flatten([$., YS, $_, MS, $_, DS, $_, HS]).
-spec zeropad(integer(), integer()) -> string().
zeropad(Num, MinLength) ->
NumStr = integer_to_list(Num),
zeropad_str(NumStr, MinLength - length(NumStr)).
-spec zeropad_str(string(), integer()) -> string().
zeropad_str(NumStr, Zeros) when Zeros > 0 ->
zeropad_str([$0 | NumStr], Zeros - 1);
zeropad_str(NumStr, _) ->
NumStr.
-spec zone() -> string().
zone() ->
Time = erlang:universaltime(),
LocalTime = calendar:universal_time_to_local_time(Time),
DiffSecs = calendar:datetime_to_gregorian_seconds(LocalTime) -
calendar:datetime_to_gregorian_seconds(Time),
zone((DiffSecs/3600)*100).
%% Ugly reformatting code to get times like +0000 and -1300
-spec zone(integer()) -> string().
zone(Val) when Val < 0 ->
io_lib:format("-~4..0w", [trunc(abs(Val))]);
zone(Val) when Val >= 0 ->
io_lib:format("+~4..0w", [trunc(abs(Val))]).
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