Do the slicing in flu server rather than in CR client

src/machi_cr_client.erl

@@ -112,7 +112,6 @@
 
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
--export([trim_both_side/3]).
 -endif. % TEST.
 
 -export([start_link/1]).
@@ -529,8 +528,7 @@ do_read_chunk2(File, Offset, Size, Opts, Depth, STime, TO,
     ConsistencyMode = P#projection_v1.mode,
     case ?FLU_PC:read_chunk(orddict:fetch(Tail, PD), EpochID,
                             File, Offset, Size, Opts, ?TIMEOUT) of
-        {ok, {Chunks0, []}} when is_list(Chunks0) ->
-            Chunks = trim_both_side(Chunks0, Offset, Offset + Size),
+        {ok, {Chunks, []}} when is_list(Chunks) ->
             {reply, {ok, {Chunks, []}}, S};
         %% {ok, BadChunk} ->
         %%     %% TODO cleaner handling of bad chunks
@@ -926,28 +924,3 @@ timeout(infinity) ->
     timeout(15*60*1000);                        % close enough to infinity
 timeout(Timeout0) ->
     {Timeout0, Timeout0 + 30*1000}.
-
-%% @doc Trim both right and left border of chunks to fit in to given
-%% range [LeftPos, RightPos]. TODO: write unit tests for this function.
-trim_both_side([], _, _) -> [];
-trim_both_side([{F, Offset, Chunk, _Csum}|L], LeftPos, RightPos)
-  when Offset < LeftPos andalso LeftPos < RightPos ->
-    TrashLen = 8 * (LeftPos - Offset),
-    <<_:TrashLen/binary, NewChunk/binary>> = Chunk,
-    %% CR Client is client or server?
-    NewChecksum = machi_util:make_tagged_csum(client_sha, Chunk),
-    NewH = {F, LeftPos, NewChunk, NewChecksum},
-    trim_both_side([NewH|L], LeftPos, RightPos);
-trim_both_side(Chunks, LeftPos, RightPos) when LeftPos =< RightPos ->
-    %% TODO: optimize
-    [{F, Offset, Chunk, _Csum}|L] = lists:reverse(Chunks),
-    Size = iolist_size(Chunk),
-    if RightPos < Offset + Size ->
-            NewSize = RightPos - Offset,
-            <<NewChunk:NewSize/binary, _/binary>> = Chunk,
-            %% CR Client is client or server?
-            NewChecksum = machi_util:make_tagged_csum(client_sha, Chunk),
-            lists:reverse([{F, Offset, NewChunk, NewChecksum}|L]);
-       true ->
-            Chunks
-    end.

src/machi_file_proxy.erl

@@ -281,9 +281,7 @@ handle_call({read, Offset, Length, Opts}, _From,
             State = #state{filename = F,
                            data_filehandle = FH,
                            csum_table = CsumTable,
-                           eof_position = EofP,
-                           reads = {T, Err}
-                          }) ->
+                           reads = {T, Err}}) ->
     NoChecksum = proplists:get_value(no_checksum, Opts, false),
     NoChunk = proplists:get_value(no_chunk, Opts, false),
     NeedsMerge = proplists:get_value(needs_trimmed, Opts, false),
@@ -291,12 +289,9 @@ handle_call({read, Offset, Length, Opts}, _From,
         case do_read(FH, F, CsumTable, Offset, Length, NoChecksum, NoChunk, NeedsMerge) of
             {ok, {[], []}} ->
                 {{error, not_written}, Err + 1};
-            {ok, {Chunks, Trimmed}} ->
-                %% Kludge to wrap read result in tuples, to support fragmented read
-                %% XXX FIXME 
-                %% For now we are omiting the checksum data because it blows up
-                %% protobufs.
-                {{ok, {Chunks, Trimmed}}, Err};
+            {ok, {Chunks0, Trimmed0}} ->
+                Chunks = slice_both_side(Chunks0, Offset, Offset+Length),
+                {{ok, {Chunks, Trimmed0}}, Err};
             Error ->
                 lager:error("Can't read ~p, ~p at File ~p", [Offset, Length, F]),
                 {Error, Err + 1}
@@ -664,3 +659,26 @@ do_write(FHd, CsumTable, Filename, TaggedCsum, Offset, Size, Data) ->
             [Other, Filename, Offset, Size]),
             {error, Other}
     end.
+
+%% @doc Trim both right and left border of chunks to fit in to given
+%% range [LeftPos, RightPos]. TODO: write unit tests for this function.
+slice_both_side([], _, _) -> [];
+slice_both_side([{F, Offset, Chunk, _Csum}|L], LeftPos, RightPos)
+  when Offset < LeftPos andalso LeftPos < RightPos ->
+    TrashLen = 8 * (LeftPos - Offset),
+    <<_:TrashLen/binary, NewChunk/binary>> = Chunk,
+    NewChecksum = machi_util:make_tagged_csum(client_sha, Chunk),
+    NewH = {F, LeftPos, NewChunk, NewChecksum},
+    slice_both_side([NewH|L], LeftPos, RightPos);
+slice_both_side(Chunks, LeftPos, RightPos) when LeftPos =< RightPos ->
+    %% TODO: optimize
+    [{F, Offset, Chunk, _Csum}|L] = lists:reverse(Chunks),
+    Size = iolist_size(Chunk),
+    if RightPos < Offset + Size ->
+            NewSize = RightPos - Offset,
+            <<NewChunk:NewSize/binary, _/binary>> = Chunk,
+            NewChecksum = machi_util:make_tagged_csum(client_sha, Chunk),
+            lists:reverse([{F, Offset, NewChunk, NewChecksum}|L]);
+       true ->
+            Chunks
+    end.

test/machi_file_proxy_eqc.erl

@@ -203,8 +203,7 @@ read_next(S, _Res, _Args) -> S.
 read(Pid, Offset, Length) ->
     case machi_file_proxy:read(Pid, Offset, Length) of
         {ok, {Chunks, _}} ->
-            [{_, Offset, Data, Csum}] =
-                machi_cr_client:trim_both_side(Chunks, Offset, Offset+Length),
+            [{_, Offset, Data, Csum}] = Chunks,
             {ok, Data, Csum};
         E ->
             E