greg/machi
1
0
Fork 0
Code Issues 11 Pull requests 1 Projects Releases Packages Wiki Activity Actions

Read-repair, not tested

Browse source
This commit is contained in:
Scott Lystig Fritchie 2014-02-16 17:31:41 +09:00
parent 945635f837
commit c23aeabc20
1 changed files with 53 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

54
prototype/corfurl/src/corfurl.erl
View file

@ -133,10 +133,62 @@ read_page(#proj{epoch=Epoch} = P, LPN) ->
error_overwritten ->
error({impossible, ?MODULE, ?LINE, overwritten_reply_to_read});
error_unwritten ->
%% TODO: Check head for possible read-repair
%% TODO: During scan_forward(), this pestering of the upstream
%% nodes in the chain is possibly-excessive-work.
%% For now, we'll assume that we always want to repair.
case read_repair(Epoch, LPN, Tail, hd(Chain)) of
{ok, _} = OK2 ->
OK2;
Else ->
Else
end
end.
read_repair(_Epoch, _LPN, RepairFLU, RepairFLU) ->
error_unwritten;
read_repair(Epoch, LPN, RepairFLU, Head) ->
case corfurl_flu:read(flu_pid(Head), Epoch, LPN) of
{ok, Page} ->
case corfurl_flu:write(flu_pid(RepairFLU), Epoch, LPN, Page) of
ok ->
ok;
error_badepoch ->
error_badepoch;
error_trimmed ->
error_trimmed;
error_overwritten ->
case corfurl_flu:read(flu_pid(RepairFLU), Epoch, LPN) of
{ok, Page2} when Page2 =:= Page ->
{ok, Page};
{ok, Oops} ->
error({impossible, ?MODULE, ?LINE, LPN, head_said, Page, repairee_now_says, Oops});
error_trimmed ->
%% Wow, we have lost at least 3 races in a row.
read_repair_trim(RepairFLU, LPN);
Else ->
Else
end;
error_unwritten ->
error({impossible, ?MODULE, ?LINE, written_then_unwritten})
end;
error_badepoch ->
error_badepoch;
error_trimmed ->
read_repair_trim(RepairFLU, LPN);
error_overwritten ->
error({impossible, ?MODULE, ?LINE, overwritten_reply_to_read});
error_unwritten ->
error_unwritten
end.
read_repair_trim(RepairFLU, LPN) ->
case corfurl_flu:trim(flu_pid(RepairFLU), LPN) of
ok ->
error_trimmed;
Else ->
Else
end.
scan_forward(P, LPN, MaxPages) ->
scan_forward(P, LPN, MaxPages, ok, true, []).