admin: add clear_cache command

Currently a no-op in MogileFS 2.55, but it was useful at one
point in the past and may be in the future.

3 files changed, 40 insertions, 0 deletions

diff --git a/lib/mogilefs/admin.rb b/lib/mogilefs/admin.rb
index 51d507d..1bba4a2 100644
--- a/lib/mogilefs/admin.rb
+++ b/lib/mogilefs/admin.rb
@@ -259,6 +259,10 @@ class MogileFS::Admin < MogileFS::Client
     rv
   end
 
+  def clear_cache
+    @backend.clear_cache
+  end
+
   protected unless defined? $TESTING
 
   ##
diff --git a/lib/mogilefs/backend.rb b/lib/mogilefs/backend.rb
index f4c7254..b754bbc 100644
--- a/lib/mogilefs/backend.rb
+++ b/lib/mogilefs/backend.rb
@@ -312,6 +312,38 @@ class MogileFS::Backend
           "Invalid response from server: #{line.inspect}"
   end
 
+  # this command is special since the cache is per-tracker, so we connect
+  # to all backends and not just one
+  def clear_cache(types = %w(all))
+    opts = {}
+    types.each { |type| opts[type] = 1 }
+
+    sockets = @hosts.map do |host|
+      MogileFS::Socket.start(*(host.split(/:/))) rescue nil
+    end
+    sockets.compact!
+
+    wpending = sockets
+    rpending = []
+    request = make_request("clear_cache", opts)
+    while wpending[0] || rpending[0]
+      r = IO.select(rpending, wpending, nil, @timeout) or return
+      rpending -= r[0]
+      wpending -= r[1]
+      r[0].each { |io| io.timed_gets(0) rescue nil }
+      r[1].each do |io|
+        begin
+          io.timed_write(request, 0)
+          rpending << io
+        rescue
+        end
+      end
+    end
+    nil
+    ensure
+      sockets.each { |io| io.close }
+  end
+
   # Returns a socket connected to a MogileFS tracker.
   def socket
     return @socket if @socket and not @socket.closed?
diff --git a/test/test_fresh.rb b/test/test_fresh.rb
index 9b279c6..4afed06 100644
--- a/test/test_fresh.rb
+++ b/test/test_fresh.rb
@@ -99,6 +99,10 @@ EOF
     assert_equal({"count" => 0}, @admin.replicate_now)
   end
 
+  def test_clear_cache
+    assert_nil @admin.clear_cache
+  end
+
   def test_create_update_delete_class
     domain = "rbmogtest#{Time.now.strftime('%Y%m%d%H%M%S')}.#{uuid}"
     @admin.create_domain(domain)