From ee33a6ed7cf2549c420ebc9f62b4c005a2b738f8 Mon Sep 17 00:00:00 2001
From: Takahiro OSAKADA <t-osakada@iij.ad.jp>
Date: Fri, 17 Feb 2017 12:10:24 +0900
Subject: [PATCH] Watch only recently modified files

---
 lib/fluent/plugin/in_tail.rb |  8 +++++++-
 test/plugin/test_in_tail.rb  | 24 ++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/fluent/plugin/in_tail.rb b/lib/fluent/plugin/in_tail.rb
index fe6e0ba847..3fe47c90c4 100644
--- a/lib/fluent/plugin/in_tail.rb
+++ b/lib/fluent/plugin/in_tail.rb
@@ -77,6 +77,8 @@ def initialize
     config_param :path_key, :string, default: nil
     desc 'Open and close the file on every update instead of leaving it open until it gets rotated.'
     config_param :open_on_every_update, :bool, default: false
+    desc 'Limit the watching files that the modification time is within the specified time range (when use \'*\' in path).'
+    config_param :limit_recently_modified, :time, default: nil
 
     attr_reader :paths
 
@@ -186,7 +188,11 @@ def expand_paths
         if path.include?('*')
           paths += Dir.glob(path).select { |p|
             if File.readable?(p) && !File.directory?(p)
-              true
+              if @limit_recently_modified && File.mtime(p) < (date - @limit_recently_modified)
+                false
+              else
+                true
+              end
             else
               log.warn "#{p} unreadable. It is excluded and would be examined next time."
               false
diff --git a/test/plugin/test_in_tail.rb b/test/plugin/test_in_tail.rb
index dd6e2b7360..590c5016c5 100644
--- a/test/plugin/test_in_tail.rb
+++ b/test/plugin/test_in_tail.rb
@@ -1174,4 +1174,28 @@ def test_tail_path_with_multiline_with_multiple_paths
       assert_equal(files, [events[2][2]["path"], events[3][2]["path"]].sort)
     end
   end
+
+  def test_limit_recently_modified
+    now = Time.new(2010, 1, 2, 3, 4, 5)
+    FileUtils.touch("#{TMP_DIR}/tail_unwatch.txt", mtime: (now - 3601))
+    FileUtils.touch("#{TMP_DIR}/tail_watch1.txt", mtime: (now - 3600))
+    FileUtils.touch("#{TMP_DIR}/tail_watch2.txt", mtime: now)
+
+    config = config_element('', '', {
+      'tag' => 'tail',
+      'path' => "#{TMP_DIR}/*.txt",
+      'format' => 'none',
+      'limit_recently_modified' => '3600s'
+    })
+
+    expected_files = [
+      "#{TMP_DIR}/tail_watch1.txt",
+      "#{TMP_DIR}/tail_watch2.txt"
+    ]
+
+    Timecop.freeze(now) do
+      plugin = create_driver(config, false).instance
+      assert_equal expected_files, plugin.expand_paths.sort
+    end
+  end
 end