From a331b87caa2ce4f3f664cdba8aef77e07055fe50 Mon Sep 17 00:00:00 2001
From: Wilson Li <windkithk@gmail.com>
Date: Fri, 20 Oct 2017 11:45:13 +0900
Subject: [PATCH] Update to README about custom rotator and hour specification

---
 README.md                  | 44 ++++++++++++++++++++++++++++++++++++++
 src/lager_file_backend.erl |  4 ++--
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 5858a8f..1376846 100644
--- a/README.md
+++ b/README.md
@@ -521,6 +521,22 @@ Some examples:
           6:00 hr
 ```
 
+On top of the day, week and month time format from newsyslog,
+hour specification is added from PR [#420](https://github.com/erlang-lager/lager/pull/420)
+
+```
+Format of hour specification is : [Hmm]
+The range for minute specification is:
+
+  mm      minutes, range 0 ... 59
+
+Some examples:
+
+  $H00    rotate every hour at HH:00
+  $D12H30 rotate every day at 12:30
+  $W0D0H0 rotate every week on Sunday at 00:00
+```
+
 To configure the crash log rotation, the following application variables are
 used:
 * `crash_log_size`
@@ -529,6 +545,34 @@ used:
 
 See the `.app.src` file for further details.
 
+Custom Log Rotation
+-------------------
+Custom log rotator could be configured with option for `lager_file_backend`
+```erlang
+{rotator, lager_util}
+```
+
+The module should provide the following callbacks as `lager_rotator_behaviour`
+
+```erlang
+%% @doc Create a log file
+-callback(create_logfile(Name::list(), Buffer::{integer(), integer()} | any()) ->
+    {ok, {FD::file:io_device(), Inode::integer(), Size::integer()}} | {error, any()}).
+
+%% @doc Open a log file
+-callback(open_logfile(Name::list(), Buffer::{integer(), integer()} | any()) ->
+    {ok, {FD::file:io_device(), Inode::integer(), Size::integer()}} | {error, any()}).
+
+%% @doc Ensure reference to current target, could be rotated
+-callback(ensure_logfile(Name::list(), FD::file:io_device(), Inode::integer(),
+                         Buffer::{integer(), integer()} | any()) ->
+    {ok, {FD::file:io_device(), Inode::integer(), Size::integer()}} | {error, any()}).
+
+%% @doc Rotate the log file
+-callback(rotate_logfile(Name::list(), Count::integer()) ->
+    ok).
+```
+
 Syslog Support
 --------------
 Lager syslog output is provided as a separate application:
diff --git a/src/lager_file_backend.erl b/src/lager_file_backend.erl
index c6f031d..e606fd7 100644
--- a/src/lager_file_backend.erl
+++ b/src/lager_file_backend.erl
@@ -111,8 +111,8 @@ init(LogFileConfig) when is_list(LogFileConfig) ->
             {error, {fatal, bad_config}};
         Config ->
             %% probabably a better way to do this, but whatever
-            [RelName, Level, Date, Size, Count, Rotator, HighWaterMark, SyncInterval, SyncSize, SyncOn, CheckInterval, Formatter, FormatterConfig] =
-              [proplists:get_value(Key, Config) || Key <- [file, level, date, size, count, rotator, high_water_mark, sync_interval, sync_size, sync_on, check_interval, formatter, formatter_config]],
+            [RelName, Level, Date, Size, Count, Rotator, HighWaterMark, Flush, SyncInterval, SyncSize, SyncOn, CheckInterval, Formatter, FormatterConfig] =
+              [proplists:get_value(Key, Config) || Key <- [file, level, date, size, count, rotator, high_water_mark, flush_queue, sync_interval, sync_size, sync_on, check_interval, formatter, formatter_config]],
             FlushThr = proplists:get_value(flush_threshold, Config, 0),
             Name = lager_util:expand_path(RelName),
             schedule_rotation(Name, Date),