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osiris_log: Merge read_ahead toggle and limit options #199

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osiris_log: Merge read_ahead toggle and limit options #199

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3 changes: 1 addition & 2 deletions src/osiris.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -83,8 +83,7 @@
-type reader_options() :: #{transport => tcp | ssl,
chunk_selector => all | user_data,
filter_spec => osiris_bloom:filter_spec(),
read_ahead => boolean(),
read_ahead_limit => pos_integer()
read_ahead => boolean() | non_neg_integer()
}.

-export_type([name/0,
Expand Down
27 changes: 16 additions & 11 deletions src/osiris_log.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -423,10 +423,11 @@
filter_size = ?DEFAULT_FILTER_SIZE :: osiris_bloom:filter_size()
}).
-record(ra,
{on = true :: boolean(),
size = ?HEADER_SIZE_B + ?DEFAULT_FILTER_SIZE :: non_neg_integer(),
{size = ?HEADER_SIZE_B + ?DEFAULT_FILTER_SIZE :: non_neg_integer(),
buf :: undefined | {Pos :: non_neg_integer(), binary()},
limit = ?DEFAULT_READ_AHEAD_LIMIT :: pos_integer()
%% Max number of bytes that can be read ahead. Set to zero to
%% turn off read-ahead.
limit = ?DEFAULT_READ_AHEAD_LIMIT :: non_neg_integer()
}).
-record(read,
{type :: data | offset,
Expand Down Expand Up @@ -3312,7 +3313,7 @@ iter_guess_size(Credit0, NumEntries, DataSize) ->
(DataSize div NumEntries * Credit).

iter_read_ahead(Fd, Pos, MinReqSize, Credit0, DataSize, NumEntries,
#ra{limit = ReadAheadLimit} = Ra0)
#ra{limit = ReadAheadLimit0} = Ra0)
when is_integer(Credit0) andalso
MinReqSize =< DataSize ->
%% if the minimum request size can be served from read ahead then we
Expand All @@ -3335,6 +3336,8 @@ iter_read_ahead(Fd, Pos, MinReqSize, Credit0, DataSize, NumEntries,
%% needed to serve that, else we read up to the readahead
%% limit but not beyond the end of the chunk and not less
%% that the minimum request size
ReadAheadLimit = max(ReadAheadLimit0,
?DEFAULT_READ_AHEAD_LIMIT),
MinSize = max(MinReqSize, min(ReadAheadLimit, DataSize)),
Size = max(MinSize, iter_guess_size(Credit0, NumEntries,
DataSize)),
Expand Down Expand Up @@ -3364,15 +3367,17 @@ ra_read(_Pos, _Len, _Ra) ->
undefined.

ra_update_size(undefined, FilterSize, LastDataSize,
#ra{on = true, size = Sz, limit = Limit} = Ra)
when Sz < Limit andalso
#ra{size = Sz, limit = Limit} = Ra)
when Limit =/= 0 andalso
Sz < Limit andalso
LastDataSize =< (Limit - ?HEADER_SIZE_B -
FilterSize - ?REC_HDR_SZ_SUBBATCH_B) ->
%% no filter and last data size was small so enable data read ahead
Ra#ra{size = Limit};
ra_update_size(undefined, FilterSize, LastDataSize,
#ra{on = true, size = Limit, limit = Limit} = Ra)
when LastDataSize =< (Limit - ?HEADER_SIZE_B -
#ra{size = Limit, limit = Limit} = Ra)
when Limit =/= 0 andalso
LastDataSize =< (Limit - ?HEADER_SIZE_B -
FilterSize - ?REC_HDR_SZ_SUBBATCH_B) ->
Ra;
ra_update_size(_Filter, FilterSize, _LastDataSize, #ra{size = Sz} = Ra) ->
Expand All @@ -3399,11 +3404,11 @@ ra_fill(Fd, Pos, #ra{size = Sz} = Ra) ->

-spec ra(config()) -> #ra{}.
ra(#{options := #{read_ahead := false}}) ->
#ra{on = false};
ra(#{options := #{read_ahead_limit := Limit}}) when is_integer(Limit) ->
#ra{limit = 0};
ra(#{options := #{read_ahead := Limit}}) when is_integer(Limit) ->
#ra{limit = Limit};
ra(_) ->
#ra{on = true}.
#ra{}.

generate_log(Msg, MsgsPerChunk, NumMessages, Directory) ->
Name = filename:basename(Directory),
Expand Down