Author: fdmanana
Date: Wed Nov 10 21:14:00 2010
New Revision: 1033714
URL: http://svn.apache.org/viewvc?rev=1033714&view=rev
Log:
Micro optimization: faster header reads (read the whole block at once, so far
headers are always smaller than a block). Read time is basically reduced to
half.
Modified:
couchdb/trunk/src/couchdb/couch_file.erl
Modified: couchdb/trunk/src/couchdb/couch_file.erl
URL:
http://svn.apache.org/viewvc/couchdb/trunk/src/couchdb/couch_file.erl?rev=1033714&r1=1033713&r2=1033714&view=diff
==============================================================================
--- couchdb/trunk/src/couchdb/couch_file.erl (original)
+++ couchdb/trunk/src/couchdb/couch_file.erl Wed Nov 10 21:14:00 2010
@@ -486,11 +486,18 @@ find_header(Fd, Block) ->
end.
load_header(Fd, Block) ->
- {ok, <<1>>} = file:pread(Fd, Block*?SIZE_BLOCK, 1),
- {ok, <<HeaderLen:32/integer>>} = file:pread(Fd, (Block*?SIZE_BLOCK) + 1,
4),
+ {ok, <<1, HeaderLen:32/integer, RestBlock/binary>>} =
+ file:pread(Fd, Block * ?SIZE_BLOCK, ?SIZE_BLOCK),
TotalBytes = calculate_total_read_len(1, HeaderLen),
- {ok, <<RawBin:TotalBytes/binary>>} =
- file:pread(Fd, (Block*?SIZE_BLOCK) + 5, TotalBytes),
+ case TotalBytes > byte_size(RestBlock) of
+ false ->
+ <<RawBin:TotalBytes/binary, _/binary>> = RestBlock;
+ true ->
+ {ok, Missing} = file:pread(
+ Fd, (Block * ?SIZE_BLOCK) + 5 + byte_size(RestBlock),
+ TotalBytes - byte_size(RestBlock)),
+ RawBin = <<RestBlock/binary, Missing/binary>>
+ end,
<<Md5Sig:16/binary, HeaderBin/binary>> =
iolist_to_binary(remove_block_prefixes(1, RawBin)),
Md5Sig = couch_util:md5(HeaderBin),
