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vatamane pushed a commit to branch wip-suggest-fsync-header
in repository https://gitbox.apache.org/repos/asf/couchdb.git
The following commit(s) were added to refs/heads/wip-suggest-fsync-header by
this push:
new d41d58687 wip suggestion for fsync pr
d41d58687 is described below
commit d41d58687771f06e80fceaff2878ff9868f37765
Author: Nick Vatamaniuc <[email protected]>
AuthorDate: Mon Jun 23 15:44:15 2025 -0400
wip suggestion for fsync pr
---
src/couch/src/couch_file.erl | 61 ++++++++++++++++++++++++++++++++------------
1 file changed, 45 insertions(+), 16 deletions(-)
diff --git a/src/couch/src/couch_file.erl b/src/couch/src/couch_file.erl
index 24c910302..4b377d33c 100644
--- a/src/couch/src/couch_file.erl
+++ b/src/couch/src/couch_file.erl
@@ -47,7 +47,7 @@
-export([append_term/2, append_term/3]).
-export([pread_terms/2]).
-export([append_terms/2, append_terms/3]).
--export([write_header/2, read_header/1]).
+-export([write_header/2, write_header/3, read_header/1]).
-export([delete/2, delete/3, nuke_dir/2, init_delete_dir/1]).
% gen_server callbacks
@@ -433,11 +433,16 @@ read_header(Fd) ->
end.
write_header(Fd, Data) ->
+ write_header(Fd, Data, []).
+
+% Only the sync option is currently supported
+%
+write_header(Fd, Data, Opts) when is_list(Opts) ->
Bin = ?term_to_bin(Data),
Checksum = generate_checksum(Bin),
% now we assemble the final header binary and write to disk
FinalBin = <<Checksum/binary, Bin/binary>>,
- ioq:call(Fd, {write_header, FinalBin}, erlang:get(io_priority)).
+ ioq:call(Fd, {write_header, FinalBin, Opts}, erlang:get(io_priority)).
init_status_error(ReturnPid, Ref, Error) ->
ReturnPid ! {Ref, self(), Error},
@@ -580,20 +585,21 @@ handle_call({append_bins, Bins}, _From, #file{} = File) ->
{{ok, Resps}, File1} -> {reply, {ok, Resps}, File1};
{Error, File1} -> {reply, Error, File1}
end;
-handle_call({write_header, Bin}, _From, #file{fd = Fd, eof = Pos} = File) ->
- BinSize = byte_size(Bin),
- case Pos rem ?SIZE_BLOCK of
- 0 ->
- Padding = <<>>;
- BlockOffset ->
- Padding = <<0:(8 * (?SIZE_BLOCK - BlockOffset))>>
- end,
- FinalBin = [Padding, <<1, BinSize:32/integer>> | make_blocks(5, [Bin])],
- case file:write(Fd, FinalBin) of
- ok ->
- {reply, ok, File#file{eof = Pos + iolist_size(FinalBin)}};
- Error ->
- {reply, Error, reset_eof(File)}
+handle_call({write_header, Bin, Opts}, _From, #file{} = File) ->
+ try
+ ok = header_fsync(File, Opts),
+ case handle_write_header(Bin, File) of
+ {ok, NewFile} ->
+ ok = header_fsync(NewFile, Opts),
+ {reply, ok, NewFile};
+ {{error, Err}, NewFile} ->
+ {reply, {error, Err}, NewFile}
+ end
+ catch
+ error:{fsync_error, Error} ->
+ % If fsync error happens we stop. See comment in
+ % handle_call(sync, ...) why we're dropping the fd
+ {stop, {error, Error}, {error, Error}, #file{fd = nil}}
end;
handle_call(find_header, _From, #file{fd = Fd, eof = Pos} = File) ->
{reply, find_header(Fd, Pos div ?SIZE_BLOCK), File}.
@@ -659,6 +665,17 @@ pread(#file{} = File, PosL) ->
Extracted = lists:zipwith(ZipFun, DataSizes, Resps),
{ok, Extracted}.
+header_fsync(#file{fd = Fd}, Opts) when is_list(Opts) ->
+ case couch_util:get_value(sync, Opts, false) of
+ true ->
+ case fsync(Fd) of
+ ok -> ok;
+ {error, Err} -> error({fsync_error, Err})
+ end;
+ false ->
+ ok
+ end.
+
fsync(Fd) ->
T0 = erlang:monotonic_time(),
% We do not rely on mtime/atime for our safety/consitency so we can use
@@ -757,6 +774,18 @@ find_newest_header(Fd, [{Location, Size} | LocationSizes])
->
find_newest_header(Fd, LocationSizes)
end.
+handle_write_header(Bin, #file{fd = Fd, eof = Pos} = File) ->
+ BinSize = byte_size(Bin),
+ case Pos rem ?SIZE_BLOCK of
+ 0 -> Padding = <<>>;
+ BlockOffset -> Padding = <<0:(8 * (?SIZE_BLOCK - BlockOffset))>>
+ end,
+ FinalBin = [Padding, <<1, BinSize:32/integer>> | make_blocks(5, [Bin])],
+ case file:write(Fd, FinalBin) of
+ ok -> {ok, File#file{eof = Pos + iolist_size(FinalBin)}};
+ {error, Error} -> {{error, Error}, reset_eof(File)}
+ end.
+
read_multi_raw_iolists_int(#file{fd = Fd, eof = Eof} = File, PosLens) ->
MapFun = fun({Pos, Len}) -> get_pread_locnum(File, Pos, Len) end,
LocNums = lists:map(MapFun, PosLens),
