diff options
Diffstat (limited to 'src/index.erl')
-rw-r--r-- | src/index.erl | 80 |
1 files changed, 53 insertions, 27 deletions
diff --git a/src/index.erl b/src/index.erl index a2b5c4a..96195e3 100644 --- a/src/index.erl +++ b/src/index.erl @@ -1,17 +1,18 @@ %%% Copyright (c) 2014, NORDUnet A/S. %%% See LICENSE for licensing information. -%% Implements an interface to a file pair (basename and basename.chksum) -%% that stores an ordered list of fixed-size entries. Entries can be -%% added at the end and are retrieved by index. The list can also be -%% truncated. +%% Implements an interface to a file pair (basename and +%% basename.chksum) that stores an ordered list of fixed-size entries. +%% Entries can be added at the end and are retrieved by index. Entries +%% can also be added at already existing indices, but then the +%% contents must be the same. %% -%% Writes(add, truncate, addlast) need to be serialized. +%% Writes(add, addlast) need to be serialized. %% TODO: Checksums -module(index). --export([get/2, getrange/3, add/3, addlast/2, truncate/2]). +-export([get/2, getrange/3, add/3, addlast/2, indexsize/1]). -define(ENTRYSIZE, 32). -define(ENTRYSIZEINFILE, (?ENTRYSIZE*2+1)). @@ -21,27 +22,38 @@ add(Basepath, Index, Entry) when is_binary(Entry), size(Entry) == ?ENTRYSIZE -> case file:open(Basepath, [read, write, binary]) of {ok, File} -> {ok, Position} = file:position(File, eof), - case Index of - last when Position rem ?ENTRYSIZEINFILE == 0 -> - ok; - Index when is_integer(Index), - Index * ?ENTRYSIZEINFILE == Position -> - ok - end, + Mode = case Index of + last when Position rem ?ENTRYSIZEINFILE == 0 -> + write; + Index when is_integer(Index), + Index * ?ENTRYSIZEINFILE == Position -> + write; + Index when is_integer(Index), + Index * ?ENTRYSIZEINFILE < Position -> + read; + _ -> + util:exit_with_error(invalid, writefile, + "Index not valid") + end, EntryText = hex:bin_to_hexstr(Entry) ++ "\n", - ok = file:write(File, EntryText), - ok = file:close(File), - util:fsync([Basepath, filename:dirname(Basepath)]); - {error, Error} -> - util:exit_with_error(Error, writefile, - "Error opening file for writing") - end. - -truncate(Basepath, Index) -> - case file:open(Basepath, [read, write, binary]) of - {ok, File} -> - {ok, _Position} = file:position(File, Index * ?ENTRYSIZEINFILE), - ok = file:truncate(File), + case Mode of + write -> + ok = file:write(File, EntryText); + read -> + {ok, _Position} = + file:position(File, {bof, Index * ?ENTRYSIZEINFILE}), + {ok, OldEntryText} = file:read(File, ?ENTRYSIZEINFILE), + %% check that the written content is the same as + %% the old content + case binary_to_list(OldEntryText) of + EntryText -> + ok; + _ -> + util:exit_with_error(invalid, writefile, + "Written content not the" ++ + " same as old content") + end + end, ok = file:close(File), util:fsync([Basepath, filename:dirname(Basepath)]); {error, Error} -> @@ -65,7 +77,19 @@ decodedata(<<_:?ENTRYSIZE/binary-unit:16, _>>, _Acc) -> util:exit_with_error(badformat, readindex, "Index line not ending with linefeed"). --spec get(string(), integer()) -> binary(). +-spec indexsize(string()) -> integer(). +indexsize(Basepath) -> + case file:open(Basepath, [read, binary]) of + {ok, File} -> + {ok, Filesize} = file:position(File, eof), + lager:debug("file ~p size ~p", [Basepath, Filesize]), + Filesize div ?ENTRYSIZEINFILE; + {error, Error} -> + util:exit_with_error(Error, readfile, + "Error opening file for reading") + end. + +-spec get(string(), integer()) -> binary() | noentry. get(Basepath, Index) -> case getrange(Basepath, Index, Index) of noentry -> @@ -76,6 +100,7 @@ get(Basepath, Index) -> -spec getrange(string(), integer(), integer()) -> [binary()]. getrange(Basepath, Start, End) when Start =< End -> + lager:debug("path ~p start ~p end ~p", [Basepath, Start, End]), case file:open(Basepath, [read, binary]) of {ok, File} -> {ok, Filesize} = file:position(File, eof), @@ -86,6 +111,7 @@ getrange(Basepath, Start, End) when Start =< End -> {ok, EntryText} = file:read(File, ?ENTRYSIZEINFILE * (End - Start + 1)), Entry = decodedata(EntryText), + lager:debug("entries ~p", [length(Entry)]), file:close(File), Entry; true -> |