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Subject: svn commit: r1044284 -
 /couchdb/branches/1.0.x/src/couchdb/couch_file.erl
Date: Fri, 10 Dec 2010 11:03:48 -0000
To: commits@couchdb.apache.org
From: fdmanana@apache.org
Message-Id: <20101210110348.7932B2388994@eris.apache.org>

Author: fdmanana
Date: Fri Dec 10 11:03:48 2010
New Revision: 1044284

URL: http://svn.apache.org/viewvc?rev=1044284&view=rev
Log:
Merged revision 1043524 from trunk

   Calculate and verify MD5 digests outside of a couch_file server

   This has a significant positive impact on the performance, both for readers and writers,
   when there are several requests in parallel acessing the same database or view index file.

   $ node tests/compare_write_and_read.js --wclients 100 --rclients 200 \
     -name1 md5_out -name2 trunk \
     -url1 http://localhost:5984/ -url2 http://localhost:5985/ \
     --duration 120


   run 1) http://graphs.mikeal.couchone.com/#/graph/5c859b3e7d1b9bd0488cfe271105130c

   run 2) http://graphs.mikeal.couchone.com/#/graph/5c859b3e7d1b9bd0488cfe2711051bba

   Closes COUCHDB-980


Modified:
    couchdb/branches/1.0.x/src/couchdb/couch_file.erl

Modified: couchdb/branches/1.0.x/src/couchdb/couch_file.erl
URL: http://svn.apache.org/viewvc/couchdb/branches/1.0.x/src/couchdb/couch_file.erl?rev=1044284&r1=1044283&r2=1044284&view=diff
==============================================================================
--- couchdb/branches/1.0.x/src/couchdb/couch_file.erl (original)
+++ couchdb/branches/1.0.x/src/couchdb/couch_file.erl Fri Dec 10 11:03:48 2010
@@ -120,7 +120,19 @@ pread_binary(Fd, Pos) ->
 
 
 pread_iolist(Fd, Pos) ->
-    gen_server:call(Fd, {pread_iolist, Pos}, infinity).
+    case gen_server:call(Fd, {pread_iolist, Pos}, infinity) of
+    {ok, IoList, <<>>} ->
+        {ok, IoList};
+    {ok, IoList, Md5} ->
+        case couch_util:md5(IoList) of
+        Md5 ->
+            {ok, IoList};
+        _ ->
+            exit({file_corruption, <<"file corruption">>})
+        end;
+    Error ->
+        Error
+    end.
 
 %%----------------------------------------------------------------------
 %% Purpose: The length of a file, in bytes.
@@ -298,15 +310,10 @@ handle_call({pread_iolist, Pos}, _From, 
     <<1:1/integer,Len:31/integer>> -> % an MD5-prefixed term
         {Md5AndIoList, _} = read_raw_iolist_int(File, NextPos, Len+16),
         {Md5, IoList} = extract_md5(Md5AndIoList),
-        case couch_util:md5(IoList) of
-        Md5 ->
-            {reply, {ok, IoList}, File};
-        _ ->
-            {stop, file_corruption, {error,file_corruption}, File}
-        end;
+        {reply, {ok, IoList, Md5}, File};
     <<0:1/integer,Len:31/integer>> ->
         {Iolist, _} = read_raw_iolist_int(File, NextPos, Len),
-        {reply, {ok, Iolist}, File}
+        {reply, {ok, Iolist, <<>>}, File}
     end;
 handle_call({pread, Pos, Bytes}, _From, #file{fd=Fd,tail_append_begin=TailAppendBegin}=File) ->
     {ok, Bin} = file:pread(Fd, Pos, Bytes),