Clean up doc strings; add new case clause on reads
Previously if a lookup of an offset and size tuple from the process dictionary returned a checksum that was different from the one we were expecting, it would trigger a case clause exception. We should handle that case a little more elegantly.
This commit is contained in:
Mark Allen
parent
06b4890a63
commit
772a7741f2
1 changed files with 54 additions and 13 deletions
|
|
@ -34,6 +34,9 @@
|
|||
%% TODO:
|
||||
%% 1. Some way to transition the proxy into/out of a wedged state that
|
||||
%% doesn't rely on message delivery.
|
||||
%%
|
||||
%% 2. We might need a read repair command which does an unconditional write
|
||||
%% on the data block?
|
||||
|
||||
-module(machi_file_proxy).
|
||||
-behaviour(gen_server).
|
||||
|
|
@ -67,9 +70,11 @@
|
|||
-define(TIMEOUT, 10*1000).
|
||||
-define(TOO_MANY_ERRORS_RATIO, 50).
|
||||
|
||||
-type op_stats() :: { Total :: non_neg_integer(), Errors :: non_neg_integer() }.
|
||||
-type op_stats() :: { Total :: non_neg_integer(),
|
||||
Errors :: non_neg_integer() }.
|
||||
|
||||
-type byte_sequence() :: { Offset :: non_neg_integer(),
|
||||
Size :: pos_integer()|infinity }.
|
||||
Size :: pos_integer()|infinity }.
|
||||
|
||||
-record(state, {
|
||||
data_dir :: string() | undefined,
|
||||
|
|
@ -92,6 +97,10 @@
|
|||
|
||||
%% Public API
|
||||
|
||||
% @doc Start a new instance of the file proxy service. Takes the filename
|
||||
% and data directory as arguments. This function is typically called by the
|
||||
% `machi_file_proxy_sup:start_proxy/2' function.
|
||||
-spec start_link(Filename :: string(), DataDir :: string()) -> any().
|
||||
start_link(Filename, DataDir) ->
|
||||
gen_server:start_link(?MODULE, {Filename, DataDir}, []).
|
||||
|
||||
|
|
@ -121,8 +130,8 @@ write(Pid, Offset, Data) ->
|
|||
% @doc Write data at offset, including the client metadata. ClientMeta is a proplist
|
||||
% that expects the following keys and values:
|
||||
% <ul>
|
||||
% <li>`client_csum_tag' - the type of checksum from the client as defined in the machi.hrl file
|
||||
% <li>`client_csum' - the checksum value from the client
|
||||
% <li>`client_csum_tag' - the type of checksum from the client as defined in the machi.hrl file</li>
|
||||
% <li>`client_csum' - the checksum value from the client</li>
|
||||
% </ul>
|
||||
-spec write(Pid :: pid(), Offset :: non_neg_integer(), ClientMeta :: proplists:proplist(),
|
||||
Data :: binary()) -> ok|{error, term()}.
|
||||
|
|
@ -164,6 +173,7 @@ init({Filename, DataDir}) ->
|
|||
unwritten_bytes = UnwrittenBytes,
|
||||
eof_position = Eof}}.
|
||||
|
||||
% @private
|
||||
handle_call({sync, data}, _From, State = #state{ data_filehandle = FHd }) ->
|
||||
R = file:sync(FHd),
|
||||
{reply, R, State};
|
||||
|
|
@ -310,10 +320,21 @@ handle_call(Req, _From, State) ->
|
|||
lager:warning("Unknown call: ~p", [Req]),
|
||||
{reply, whoaaaaaaaaaaaa, State}.
|
||||
|
||||
% @private
|
||||
handle_cast(Cast, State) ->
|
||||
lager:warning("Unknown cast: ~p", [Cast]),
|
||||
{noreply, State}.
|
||||
|
||||
% @private
|
||||
handle_info(tick, State = #state{eof_position = Eof}) when Eof >= ?MAX_FILE_SIZE ->
|
||||
lager:notice("Eof position ~p >= max file size ~p. Shutting down.",
|
||||
[Eof, ?MAX_FILE_SIZE]),
|
||||
{stop, file_rollover, State};
|
||||
|
||||
%% XXX Is this a good idea? Need to think this through a bit.
|
||||
handle_info(tick, State = #state{wedged = true}) ->
|
||||
{stop, wedged, State};
|
||||
|
||||
%% I dunno. This may not be a good idea, but it seems like if we're throwing lots of
|
||||
%% errors, we ought to shut down and give up our file descriptors.
|
||||
handle_info(tick, State = #state{
|
||||
|
|
@ -380,8 +401,8 @@ handle_info(Req, State) ->
|
|||
lager:warning("Unknown info message: ~p", [Req]),
|
||||
{noreply, State}.
|
||||
|
||||
terminate(Reason, #state{
|
||||
filename = F,
|
||||
% @private
|
||||
terminate(Reason, #state{filename = F,
|
||||
data_filehandle = FHd,
|
||||
csum_filehandle = FHc,
|
||||
reads = {RT, RE},
|
||||
|
|
@ -397,6 +418,7 @@ terminate(Reason, #state{
|
|||
ok = file:close(FHc),
|
||||
ok.
|
||||
|
||||
% @private
|
||||
code_change(_OldVsn, State, _Extra) ->
|
||||
{ok, State}.
|
||||
|
||||
|
|
@ -524,6 +546,17 @@ do_read(FHd, Filename, TaggedCsum, Offset, Size) ->
|
|||
) -> {ok, NewU :: [byte_sequence()]} |
|
||||
{error, written} |
|
||||
{error, Reason :: term()}.
|
||||
% @private Implements the write and append operation. The first task is to
|
||||
% determine if the offset and data size has been written. If not, the write
|
||||
% is allowed proceed. A special case is made when an offset and data size
|
||||
% match a checksum. In that case we read the data off the disk, validate the
|
||||
% checksum and return a "fake" ok response as if the write had been performed
|
||||
% when it hasn't really.
|
||||
%
|
||||
% If a write proceeds, the offset, size and checksum are written to a metadata
|
||||
% file, and the internal list of unwritten bytes is modified to reflect the
|
||||
% just-performed write. This is then returned to the caller as
|
||||
% `{ok, NewUnwritten}' where NewUnwritten is the revised unwritten byte list.
|
||||
handle_write(FHd, FHc, Filename, TaggedCsum, Offset, Data, U) ->
|
||||
Size = iolist_size(Data),
|
||||
|
||||
|
|
@ -542,20 +575,27 @@ handle_write(FHd, FHc, Filename, TaggedCsum, Offset, Data, U) ->
|
|||
{ok, U};
|
||||
_ ->
|
||||
{error, written}
|
||||
end
|
||||
end;
|
||||
OtherCsum ->
|
||||
%% Got a checksum, but it doesn't match the data block's
|
||||
lager:error("During a potential write at offset ~p in file ~p, a check for unwritten bytes gave us checksum ~p but the data we were trying to trying to write has checksum ~p",
|
||||
[Offset, Filename, OtherCsum, TaggedCsum]),
|
||||
{error, written}
|
||||
end;
|
||||
true ->
|
||||
try
|
||||
do_write(FHd, FHc, Filename, TaggedCsum, Offset, Size, Data, U)
|
||||
catch
|
||||
%%% XXX FIXME: be more specific on badmatch that might
|
||||
%%% occur around line 533 when we write the checksum
|
||||
%%% occur around line 593 when we write the checksum
|
||||
%%% file entry for the data blob we just put on the disk
|
||||
error:Reason ->
|
||||
{error, Reason}
|
||||
end
|
||||
end.
|
||||
|
||||
% @private Implements the disk writes for both the write and append
|
||||
% operation.
|
||||
-spec do_write( FHd :: file:descriptor(),
|
||||
FHc :: file:descriptor(),
|
||||
Filename :: string(),
|
||||
|
|
@ -614,15 +654,16 @@ is_byte_range_unwritten(Offset, Size, Unwritten) ->
|
|||
% {Position, Space}} is returned. `not_found' is returned if no suitable
|
||||
% space is located.
|
||||
lookup_unwritten(_Offset, _Size, []) ->
|
||||
not_found;
|
||||
not_found;
|
||||
lookup_unwritten(Offset, _Size, [H={Pos, infinity}|_Rest]) when Offset >= Pos ->
|
||||
{ok, H};
|
||||
{ok, H};
|
||||
lookup_unwritten(Offset, Size, [H={Pos, Space}|_Rest])
|
||||
when Offset >= Pos andalso Offset < Pos+Space
|
||||
andalso Size =< (Space - (Offset - Pos)) ->
|
||||
{ok, H};
|
||||
{ok, H};
|
||||
lookup_unwritten(Offset, Size, [_H|Rest]) ->
|
||||
lookup_unwritten(Offset, Size, Rest).
|
||||
%% These are not the droids you're looking for.
|
||||
lookup_unwritten(Offset, Size, Rest).
|
||||
|
||||
-spec update_unwritten( Offset :: non_neg_integer(),
|
||||
Size :: pos_integer(),
|
||||
|
|
@ -645,7 +686,7 @@ update_unwritten(Offset, Size, Unwritten) ->
|
|||
-spec update_byte_range( Offset :: non_neg_integer(),
|
||||
Size :: pos_integer(),
|
||||
Sequence :: byte_sequence() ) -> Updates :: [byte_sequence()].
|
||||
% @private Given an offset and size and a byte sequence tuple where a
|
||||
% @private Given an offset and size and a byte sequence tuple where a
|
||||
% write took place, return a list of updates to the list of unwritten bytes
|
||||
% accounting for the space occupied by the just completed write.
|
||||
update_byte_range(Offset, Size, {Eof, infinity}) when Offset == Eof ->
|
||||
|
|
|
|||
Loading…
Reference in a new issue