diff options
Diffstat (limited to 'lib/stdlib/src/dets_v9.erl')
| -rw-r--r-- | lib/stdlib/src/dets_v9.erl | 118 |
1 files changed, 65 insertions, 53 deletions
diff --git a/lib/stdlib/src/dets_v9.erl b/lib/stdlib/src/dets_v9.erl index 132af01f79..f577b4410f 100644 --- a/lib/stdlib/src/dets_v9.erl +++ b/lib/stdlib/src/dets_v9.erl @@ -1,7 +1,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 2001-2010. All Rights Reserved. +%% Copyright Ericsson AB 2001-2011. All Rights Reserved. %% %% The contents of this file are subject to the Erlang Public License, %% Version 1.1, (the "License"); you may not use this file except in @@ -21,7 +21,7 @@ %% Dets files, implementation part. This module handles version 9. %% To be called from dets.erl only. --export([constants/0, mark_dirty/1, read_file_header/2, +-export([mark_dirty/1, read_file_header/2, check_file_header/2, do_perform_save/1, initiate_file/11, prep_table_copy/9, init_freelist/2, fsck_input/4, bulk_input/3, output_objs/4, bchunk_init/2, @@ -70,6 +70,17 @@ %% 16 MD5-sum for the 44 plus 112 bytes before the MD5-sum. %% (FreelistsPointer, Cookie and ClosedProperly are not digested.) %% 128 Reserved for future versions. Initially zeros. +%% Version 9(d), introduced in R15A, has instead: +%% 112 28 counters for the buddy system sizes (as for 9(b)). +%% 16 MD5-sum for the 44 plus 112 bytes before the MD5-sum. +%% (FreelistsPointer, Cookie and ClosedProperly are not digested.) +%% 4 Base of the buddy system. +%% 0 (zero) if the base is equal to ?BASE. Compatible with R14B. +%% File size at the end of the file is RealFileSize - Base. +%% The reason for modifying file size is that when a file created +%% by R15 is read by R14 a repair takes place immediately, which +%% is acceptable when downgrading. +%% 124 Reserved for future versions. Initially zeros. %% --- %% ------------------ end of file header %% 4*256 SegmentArray Pointers. @@ -86,7 +97,7 @@ %% ----------------------------- %% ??? Free lists %% ----------------------------- -%% 4 File size, in bytes. +%% 4 File size, in bytes. See 9(d) obove. %% Before we can find an object we must find the slot where the %% object resides. Each slot is a (possibly empty) list (or chain) of @@ -177,14 +188,14 @@ %%% File header %%% --define(RESERVED, 128). % Reserved for future use. +-define(RESERVED, 124). % Reserved for future use. -define(COLL_CNTRS, (28*4)). % Counters for the buddy system. -define(MD5SZ, 16). +-define(FL_BASE, 4). --define(HEADSZ, - 56+?COLL_CNTRS+?MD5SZ). % The size of the file header, in bytes, - % not including the reserved part. +-define(HEADSZ, 56+?COLL_CNTRS % The size of the file header, in bytes, + +?MD5SZ+?FL_BASE). % not including the reserved part. -define(HEADEND, (?HEADSZ+?RESERVED)). % End of header and reserved area. -define(SEGSZ, 512). % Size of a segment, in words. SZOBJP*SEGSZP. @@ -270,10 +281,6 @@ %%-define(DEBUGF(X,Y), io:format(X, Y)). -define(DEBUGF(X,Y), void). -%% {Bump} -constants() -> - {?BUMP, ?BASE}. - %% -> ok | throw({NewHead,Error}) mark_dirty(Head) -> Dirty = [{?CLOSED_PROPERLY_POS, <<?NOT_PROPERLY_CLOSED:32>>}], @@ -356,7 +363,7 @@ init_file(Fd, Tab, Fname, Type, Kp, MinSlots, MaxSlots, Ram, CacheSz, cache = dets_utils:new_cache(CacheSz), version = ?FILE_FORMAT_VERSION, bump = ?BUMP, - base = ?BASE, + base = ?BASE, % to be overwritten mod = ?MODULE }, @@ -378,13 +385,20 @@ init_file(Fd, Tab, Fname, Type, Kp, MinSlots, MaxSlots, Ram, CacheSz, {Head1, Ws1} = init_parts(Head0, 0, no_parts(Next), Zero, []), NoSegs = no_segs(Next), - {Head, WsI, WsP} = init_segments(Head1, 0, NoSegs, Zero, [], []), + {Head2, WsI, WsP} = init_segments(Head1, 0, NoSegs, Zero, [], []), Ws2 = if DoInitSegments -> WsP ++ WsI; true -> WsP end, dets_utils:pwrite(Fd, Fname, [W0 | lists:append(Ws1) ++ Ws2]), - true = hash_invars(Head), + true = hash_invars(Head2), + %% The allocations that have been made so far (parts, segments) + %% are permanent; the table will never shrink. Therefore the base + %% of the Buddy system can be set to the first free object. + %% This is used in allocate_all(), see below. + {_, Where, _} = dets_utils:alloc(Head2, ?BUMP), + NewFtab = dets_utils:init_alloc(Where), + Head = Head2#head{freelists = NewFtab, base = Where}, {ok, Head}. %% Returns a power of two not less than 256. @@ -451,8 +465,9 @@ read_file_header(Fd, FileName) -> Version:32, M:32, Next:32, Kp:32, NoObjects:32, NoKeys:32, MinNoSlots:32, MaxNoSlots:32, HashMethod:32, N:32, NoCollsB:?COLL_CNTRS/binary, - MD5:?MD5SZ/binary>> = Bin, - <<_:12/binary,MD5DigestedPart:(?HEADSZ-?MD5SZ-12)/binary,_/binary>> = Bin, + MD5:?MD5SZ/binary, FlBase:32>> = Bin, + <<_:12/binary,MD5DigestedPart:(?HEADSZ-?MD5SZ-?FL_BASE-12)/binary, + _/binary>> = Bin, {ok, EOF} = dets_utils:position_close(Fd, FileName, eof), {ok, <<FileSize:32>>} = dets_utils:pread_close(Fd, FileName, EOF-4, 4), {CL, <<>>} = lists:foldl(fun(LSz, {Acc,<<NN:32,R/binary>>}) -> @@ -468,8 +483,12 @@ read_file_header(Fd, FileName) -> true -> lists:reverse(CL) end, - + Base = case FlBase of + 0 -> ?BASE; + _ -> FlBase + end, FH = #fileheader{freelist = FreeList, + fl_base = Base, cookie = Cookie, closed_properly = CP, type = dets_utils:code_to_type(Type2), @@ -486,7 +505,7 @@ read_file_header(Fd, FileName) -> read_md5 = MD5, has_md5 = <<0:?MD5SZ/unit:8>> =/= MD5, md5 = erlang:md5(MD5DigestedPart), - trailer = FileSize, + trailer = FileSize + FlBase, eof = EOF, n = N, mod = ?MODULE}, @@ -544,7 +563,7 @@ check_file_header(FH, Fd) -> version = ?FILE_FORMAT_VERSION, mod = ?MODULE, bump = ?BUMP, - base = ?BASE}, + base = FH#fileheader.fl_base}, {ok, H, ExtraInfo}; Error -> Error @@ -1185,41 +1204,25 @@ write_loop(Head, BytesToWrite, Bin) -> write_loop(Head, BytesToWrite, SmallBin). %% By allocating bigger objects before smaller ones, holes in the -%% buddy system memory map are avoided. Unfortunately, the segments -%% are always allocated first, so if there are objects bigger than a -%% segment, there is a hole to handle. (Haven't considered placing the -%% segments among other objects of the same size.) +%% buddy system memory map are avoided. allocate_all_objects(Head, SizeT) -> DTL = lists:reverse(lists:keysort(1, ets:tab2list(SizeT))), MaxSz = element(1, hd(DTL)), - SegSize = ?ACTUAL_SEG_SIZE, - {Head1, HSz, HN, HA} = alloc_hole(MaxSz, Head, SegSize), - {Head2, NL} = allocate_all(Head1, DTL, []), + {Head1, NL} = allocate_all(Head, DTL, []), %% Find the position that will be the end of the file by allocating %% a minimal object. - {_Head, EndOfFile, _} = dets_utils:alloc(Head2, ?BUMP), - Head3 = free_hole(Head2, HSz, HN, HA), - NewHead = Head3#head{maxobjsize = max_objsize(Head3#head.no_collections)}, + {_Head, EndOfFile, _} = dets_utils:alloc(Head1, ?BUMP), + NewHead = Head1#head{maxobjsize = max_objsize(Head1#head.no_collections)}, {NewHead, NL, MaxSz, EndOfFile}. -alloc_hole(LSize, Head, SegSz) when ?POW(LSize-1) > SegSz -> - Size = ?POW(LSize-1), - {_, SegAddr, _} = dets_utils:alloc(Head, adjsz(SegSz)), - {_, Addr, _} = dets_utils:alloc(Head, adjsz(Size)), - N = (Addr - SegAddr) div SegSz, - Head1 = dets_utils:alloc_many(Head, SegSz, N, SegAddr), - {Head1, SegSz, N, SegAddr}; -alloc_hole(_MaxSz, Head, _SegSz) -> - {Head, 0, 0, 0}. - -free_hole(Head, _Size, 0, _Addr) -> - Head; -free_hole(Head, Size, N, Addr) -> - {Head1, _} = dets_utils:free(Head, Addr, adjsz(Size)), - free_hole(Head1, Size, N-1, Addr+Size). - %% One (temporary) file for each buddy size, write all objects of that %% size to the file. +%% +%% Before R15 a "hole" was needed before the first bucket if the size +%% of the biggest bucket was greater than the size of a segment. The +%% hole proved to be a problem with almost full tables with huge +%% buckets. Since R15 the hole is no longer needed due to the fact +%% that the base of the Buddy system is flexible. allocate_all(Head, [{?FSCK_SEGMENT,_,Data,_}], L) -> %% And one file for the segments... %% Note that space for the array parts and the segments has @@ -1593,23 +1596,28 @@ do_perform_save(H) -> H1 = H#head{freelists_p = FreeListsPointer}, {FLW, FLSize} = free_lists_to_file(H1), FileSize = FreeListsPointer + FLSize + 4, - ok = dets_utils:write(H1, [FLW | <<FileSize:32>>]), + AdjustedFileSize = case H#head.base of + ?BASE -> FileSize; + Base -> FileSize - Base + end, + ok = dets_utils:write(H1, [FLW | <<AdjustedFileSize:32>>]), FileHeader = file_header(H1, FreeListsPointer, ?CLOSED_PROPERLY), case dets_utils:debug_mode() of true -> - TmpHead = H1#head{freelists = init_freelist(H1, true), - fixed = false}, + TmpHead0 = init_freelist(H1#head{fixed = false}, true), + TmpHead = TmpHead0#head{base = H1#head.base}, case catch dets_utils:all_allocated_as_list(TmpHead) =:= dets_utils:all_allocated_as_list(H1) - of + of true -> dets_utils:pwrite(H1, [{0, FileHeader}]); _ -> + throw( dets_utils:corrupt_reason(H1, {failed_to_save_free_lists, FreeListsPointer, TmpHead#head.freelists, - H1#head.freelists}) + H1#head.freelists})) end; false -> dets_utils:pwrite(H1, [{0, FileHeader}]) @@ -1648,7 +1656,11 @@ file_header(Head, FreeListsPointer, ClosedProperly, NoColls) -> true -> erlang:md5(DigH); false -> <<0:?MD5SZ/unit:8>> end, - [H1, DigH, MD5 | <<0:?RESERVED/unit:8>>]. + Base = case Head#head.base of + ?BASE -> <<0:32>>; + FlBase -> <<FlBase:32>> + end, + [H1, DigH, MD5, Base | <<0:?RESERVED/unit:8>>]. %% Going through some trouble to avoid creating one single binary for %% the free lists. If the free lists are huge, binary_to_term and @@ -1695,8 +1707,8 @@ free_lists_from_file(H, Pos) -> case catch bin_to_tree([], H, start, FL, -1, []) of {'EXIT', _} -> throw({error, {bad_freelists, H#head.filename}}); - Reply -> - Reply + Ftab -> + H#head{freelists = Ftab, base = ?BASE} end. bin_to_tree(Bin, H, LastPos, Ftab, A0, L) -> |