From ae2b78b00a2c6844dfe0e0d68136ba104de359b2 Mon Sep 17 00:00:00 2001
From: Simon MacMullen <simon@rabbitmq.com>
Date: Thu, 13 Nov 2014 11:57:32 +0000
Subject: Remove a couple of TODOs, make the read buffer size configurable, and
 don't use the read buffer for the QI or msg store transform since they
 already read in decent sized chunks.

---
 src/file_handle_cache.erl | 14 ++++++++++----
 src/rabbit_msg_store.erl  |  3 ++-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/file_handle_cache.erl b/src/file_handle_cache.erl
index 06a72aa4..2922e146 100644
--- a/src/file_handle_cache.erl
+++ b/src/file_handle_cache.erl
@@ -240,7 +240,8 @@
 -spec(register_callback/3 :: (atom(), atom(), [any()]) -> 'ok').
 -spec(open/3 ::
         (file:filename(), [any()],
-         [{'write_buffer', (non_neg_integer() | 'infinity' | 'unbuffered')}])
+         [{'write_buffer', (non_neg_integer() | 'infinity' | 'unbuffered')} |
+          {'read_buffer', (non_neg_integer() | 'unbuffered')}])
         -> val_or_error(ref())).
 -spec(close/1 :: (ref()) -> ok_or_error()).
 -spec(read/2 :: (ref(), non_neg_integer()) ->
@@ -370,8 +371,8 @@ read(Ref, Count) ->
                       end;
                   eof ->
                       {eof, [Handle #handle { at_eof = true }]};
-                  Error -> %% TODO correct or change handle?
-                      {Error, [Handle]}
+                  Error ->
+                      {Error, [reset_read_buffer(Handle)]}
               end
       end).
 
@@ -768,6 +769,11 @@ new_closed_handle(Path, Mode, Options) ->
             infinity             -> infinity;
             N when is_integer(N) -> N
         end,
+    ReadBufferSize =
+        case proplists:get_value(read_buffer, Options, unbuffered) of
+            unbuffered             -> 0;
+            N2 when is_integer(N2) -> N2
+        end,
     Ref = make_ref(),
     put({Ref, fhc_handle}, #handle { hdl                     = closed,
                                      offset                  = 0,
@@ -776,7 +782,7 @@ new_closed_handle(Path, Mode, Options) ->
                                      write_buffer_size_limit = WriteBufferSize,
                                      write_buffer            = [],
                                      read_buffer_size        = 0,
-                                     read_buffer_size_limit  = 1000000, %% TODO
+                                     read_buffer_size_limit  = ReadBufferSize,
                                      read_buffer             = <<>>,
                                      at_eof                  = false,
                                      path                    = Path,
diff --git a/src/rabbit_msg_store.erl b/src/rabbit_msg_store.erl
index b829ae94..6c80ddcd 100644
--- a/src/rabbit_msg_store.erl
+++ b/src/rabbit_msg_store.erl
@@ -1299,7 +1299,8 @@ should_mask_action(CRef, MsgId,
 
 open_file(Dir, FileName, Mode) ->
     file_handle_cache:open(form_filename(Dir, FileName), ?BINARY_MODE ++ Mode,
-                           [{write_buffer, ?HANDLE_CACHE_BUFFER_SIZE}]).
+                           [{write_buffer, ?HANDLE_CACHE_BUFFER_SIZE},
+                            {read_buffer,  ?HANDLE_CACHE_BUFFER_SIZE}]).
 
 close_handle(Key, CState = #client_msstate { file_handle_cache = FHC }) ->
     CState #client_msstate { file_handle_cache = close_handle(Key, FHC) };
-- 
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