Merge pull request #866 from rabbitmq/rabbitmq-management-825

Include metrics for the time it takes to obtain a file handle

Author: michaelklishin

src/file_handle_cache.erl

@@ -315,7 +315,7 @@ open_with_absolute_path(Path, Mode, Options) ->
     case IsWriter andalso HasWriter of
         true  -> {error, writer_exists};
         false -> {ok, Ref} = new_closed_handle(Path, Mode1, Options),
-                 case get_or_reopen([{Ref, new}]) of
+                 case get_or_reopen_timed([{Ref, new}]) of
                      {ok, [_Handle1]} ->
                          RCount1 = case is_reader(Mode1) of
                                        true  -> RCount + 1;
@@ -674,7 +674,7 @@ with_handles(Refs, Fun) ->
     with_handles(Refs, reset, Fun).
 
 with_handles(Refs, ReadBuffer, Fun) ->
-    case get_or_reopen([{Ref, reopen} || Ref <- Refs]) of
+    case get_or_reopen_timed([{Ref, reopen} || Ref <- Refs]) of
         {ok, Handles0} ->
             Handles = case ReadBuffer of
                           reset -> [reset_read_buffer(H) || H <- Handles0];
@@ -712,6 +712,10 @@ with_flushed_handles(Refs, ReadBuffer, Fun) ->
               end
       end).
 
+get_or_reopen_timed(RefNewOrReopens) ->
+    file_handle_cache_stats:update(
+      io_file_handle_open_attempt, fun() -> get_or_reopen(RefNewOrReopens) end).
+
 get_or_reopen(RefNewOrReopens) ->
     case partition_handles(RefNewOrReopens) of
         {OpenHdls, []} ->

src/file_handle_cache_stats.erl

@@ -26,7 +26,7 @@
         [io_reopen, mnesia_ram_tx, mnesia_disk_tx,
          msg_store_read, msg_store_write,
          queue_index_journal_write, queue_index_write, queue_index_read]).
--define(COUNT_TIME, [io_sync, io_seek]).
+-define(COUNT_TIME, [io_sync, io_seek, io_file_handle_open_attempt]).
 -define(COUNT_TIME_BYTES, [io_read, io_write]).
 
 init() ->