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From kocol...@apache.org
Subject [7/7] git commit: updated refs/heads/1901-atomic-multipart-retries to d9837e1
Date Wed, 02 Oct 2013 16:16:24 GMT
Handle open_revs retries at a higher level

This patch disables the httpc client retries for the request to stream
document revisions to the replicator.  The retry logic at that level
could end up jumbling together response body data from different
requests and thoroughly confusing the multipart parser.  Moving the
retry logic up a level allows us to start fresh each time.

BugzID: 21367


Project: http://git-wip-us.apache.org/repos/asf/couchdb/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb/commit/a3a2a5f6
Tree: http://git-wip-us.apache.org/repos/asf/couchdb/tree/a3a2a5f6
Diff: http://git-wip-us.apache.org/repos/asf/couchdb/diff/a3a2a5f6

Branch: refs/heads/1901-atomic-multipart-retries
Commit: a3a2a5f6082f2bda9185642a344fd28af9acb348
Parents: 8d6c59d
Author: Adam Kocoloski <adam@cloudant.com>
Authored: Tue Sep 10 22:26:14 2013 -0400
Committer: Adam Kocoloski <adam@cloudant.com>
Committed: Wed Oct 2 12:11:24 2013 -0400

----------------------------------------------------------------------
 .../src/couch_replicator_api_wrap.erl           | 98 +++++++++++++-------
 1 file changed, 67 insertions(+), 31 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/couchdb/blob/a3a2a5f6/src/couch_replicator/src/couch_replicator_api_wrap.erl
----------------------------------------------------------------------
diff --git a/src/couch_replicator/src/couch_replicator_api_wrap.erl b/src/couch_replicator/src/couch_replicator_api_wrap.erl
index 9921560..28f96c0 100644
--- a/src/couch_replicator/src/couch_replicator_api_wrap.erl
+++ b/src/couch_replicator/src/couch_replicator_api_wrap.erl
@@ -48,6 +48,7 @@
     get_value/3
     ]).
 
+-define(MAX_WAIT, 5 * 60 * 1000).
 
 db_uri(#httpdb{url = Url}) ->
     couch_util:url_strip_password(Url);
@@ -157,43 +158,78 @@ get_missing_revs(Db, IdRevs) ->
 
 
 
+open_doc_revs(#httpdb{retries = 0} = HttpDb, Id, Revs, Options, _Fun, _Acc) ->
+    Path = encode_doc_id(Id),
+    QS = options_to_query_args(HttpDb, Path, [revs, {open_revs, Revs} | Options]),
+    Url = couch_util:url_strip_password(
+        couch_replicator_httpc:full_url(HttpDb, [{path,Path}, {qs,QS}])
+    ),
+    ?LOG_ERROR("Replication crashing because GET ~s failed", [Url]),
+    exit(kaboom);
 open_doc_revs(#httpdb{} = HttpDb, Id, Revs, Options, Fun, Acc) ->
     Path = encode_doc_id(Id),
-    QArgs = options_to_query_args(
-        HttpDb, Path, [revs, {open_revs, Revs} | Options]),
-    Self = self(),
-    Streamer = spawn_link(fun() ->
-            send_req(
-                HttpDb,
-                [{path, Path}, {qs, QArgs},
-                    {ibrowse_options, [{stream_to, {self(), once}}]},
-                    {headers, [{"Accept", "multipart/mixed"}]}],
-                fun(200, Headers, StreamDataFun) ->
-                    remote_open_doc_revs_streamer_start(Self),
-                    {<<"--">>, _, _} = couch_httpd:parse_multipart_request(
-                        get_value("Content-Type", Headers),
-                        StreamDataFun,
-                        fun mp_parse_mixed/1)
-                end),
-            unlink(Self)
+    QS = options_to_query_args(HttpDb, Path, [revs, {open_revs, Revs} | Options]),
+    {Pid, Ref} = spawn_monitor(fun() ->
+        Self = self(),
+        Callback = fun(200, Headers, StreamDataFun) ->
+            remote_open_doc_revs_streamer_start(Self),
+            {<<"--">>, _, _} = couch_httpd:parse_multipart_request(
+                get_value("Content-Type", Headers),
+                StreamDataFun,
+                fun mp_parse_mixed/1
+            )
+        end,
+        Streamer = spawn_link(fun() ->
+            Params = [
+                {path, Path},
+                {qs, QS},
+                {ibrowse_options, [{stream_to, {self(), once}}]},
+                {headers, [{"Accept", "multipart/mixed"}]}
+            ],
+            % We're setting retries to 0 here to avoid the case where the
+            % Streamer retries the request and ends up jumbling together two
+            % different response bodies.  Retries are handled explicitly by
+            % open_doc_revs itself.
+            send_req(HttpDb#httpdb{retries = 0}, Params, Callback)
+        end),
+        % If this process dies normally we can leave
+        % the Streamer process hanging around keeping an
+        % HTTP connection open. This is a bit of a
+        % hammer approach to making sure it releases
+        % that connection back to the pool.
+        spawn(fun() ->
+            Ref = erlang:monitor(process, Self),
+            receive
+                {'DOWN', Ref, process, Self, normal} ->
+                    exit(Streamer, {streamer_parent_died, Self});
+                {'DOWN', Ref, process, Self, _} ->
+                    ok
+                end
         end),
-    % If this process dies normally we can leave
-    % the Streamer process hanging around keeping an
-    % HTTP connection open. This is a bit of a
-    % hammer approach to making sure it releases
-    % that connection back to the pool.
-    spawn(fun() ->
-        Ref = erlang:monitor(process, Self),
         receive
-            {'DOWN', Ref, process, Self, normal} ->
-                exit(Streamer, {streamer_parent_died, Self});
-            {'DOWN', Ref, process, Self, _} ->
-                ok
-            end
+        {started_open_doc_revs, Ref} ->
+            Ret = receive_docs_loop(Streamer, Fun, Id, Revs, Ref, Acc),
+            exit({exit_ok, Ret})
+        end
     end),
     receive
-    {started_open_doc_revs, Ref} ->
-        receive_docs_loop(Streamer, Fun, Id, Revs, Ref, Acc)
+        {'DOWN', Ref, process, Pid, {exit_ok, Ret}} ->
+            Ret;
+        {'DOWN', Ref, process, Pid, Else} ->
+            Url = couch_util:url_strip_password(
+                couch_replicator_httpc:full_url(HttpDb, [{path,Path}, {qs,QS}])
+            ),
+            #httpdb{retries = Retries, wait = Wait0} = HttpDb,
+            Wait = 2 * erlang:min(Wait0 * 2, ?MAX_WAIT),
+            twig:log(notice,"Retrying GET to ~s in ~p seconds due to error ~s",
+                [Url, Wait / 1000, Else]
+            ),
+            ok = timer:sleep(Wait),
+            RetryDb = HttpDb#httpdb{
+                retries = Retries - 1,
+                wait = Wait
+            },
+            open_doc_revs(RetryDb, Id, Revs, Options, Fun, Acc)
     end;
 open_doc_revs(Db, Id, Revs, Options, Fun, Acc) ->
     {ok, Results} = couch_db:open_doc_revs(Db, Id, Revs, Options),


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