rnewson commented on a change in pull request #3507:
URL: https://github.com/apache/couchdb/pull/3507#discussion_r613406164
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File path: src/couch/src/couch_file.erl
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@@ -711,10 +711,21 @@ read_raw_iolist_int(Fd, {Pos, _Size}, Len) -> % 0110
UPGRADE CODE
read_raw_iolist_int(Fd, Pos, Len);
read_raw_iolist_int(#file{fd = Fd} = File, Pos, Len) ->
{Pos, TotalBytes} = get_pread_locnum(File, Pos, Len),
- {ok, <<RawBin:TotalBytes/binary>>} = file:pread(Fd, Pos, TotalBytes),
- {remove_block_prefixes(Pos rem ?SIZE_BLOCK, RawBin), Pos + TotalBytes}.
-
+ case catch file:pread(Fd, Pos, TotalBytes) of
+ {ok, <<RawBin:TotalBytes/binary>>} ->
+ {remove_block_prefixes(Pos rem ?SIZE_BLOCK, RawBin), Pos +
TotalBytes};
+ Else ->
+ % This clause matches when the file we are working with got
truncated
+ % outside of CouchDB after we opened it. To find affected files, we
+ % need to log the file path.
+ %
+ % Technically, this should also go into
read_multi_raw_iolists_int/2,
+ % but that doesn’t seem to be in use anywhere.
+ {_Fd, Filepath} = get(couch_file_fd),
+ throw({file_truncate_error, Else, Filepath})
Review comment:
The original behaviour caused an `exit` which we're now softening to a
`throw`. I think that's a mistake.
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