From 1b07ac052dd87d5dd255ebc328e9b8e66fac21c5 Mon Sep 17 00:00:00 2001
From: Filipe David Borba Manana <fdmanana@apache.org>
Date: Tue, 23 Nov 2010 11:35:39 +0000
Subject: Merged revision 1038067 from trunk:

Replicator DB changes:

- Added back the restriction that only the replicator can edit replication documents - this avoids
  lots of potential race conditions and confusion;
- Added more tests;
- More accurate log messages;
- Don't ignore always replication documents already tagged with a replication_id property - this
  is necessary when replicating a replicator DB from one server to another server.



git-svn-id: https://svn.apache.org/repos/asf/couchdb/branches/1.1.x@1038068 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_rep_db_listener.erl | 76 ++++++++++++++++++++++-------------
 1 file changed, 48 insertions(+), 28 deletions(-)

(limited to 'src/couchdb/couch_rep_db_listener.erl')

diff --git a/src/couchdb/couch_rep_db_listener.erl b/src/couchdb/couch_rep_db_listener.erl
index e21aafd3..5a5ab164 100644
--- a/src/couchdb/couch_rep_db_listener.erl
+++ b/src/couchdb/couch_rep_db_listener.erl
@@ -151,25 +151,23 @@ has_valid_rep_id(_Else) ->
 
 process_change({Change}) ->
     {RepProps} = JsonRepDoc = couch_util:get_value(doc, Change),
+    DocId = couch_util:get_value(<<"_id">>, RepProps),
     case couch_util:get_value(<<"deleted">>, Change, false) of
     true ->
-        maybe_stop_replication(JsonRepDoc);
+        rep_doc_deleted(DocId);
     false ->
         case couch_util:get_value(<<"state">>, RepProps) of
         <<"completed">> ->
-            maybe_stop_replication(JsonRepDoc);
+            replication_complete(DocId);
         <<"error">> ->
-            % cleanup ets table entries
-            maybe_stop_replication(JsonRepDoc);
+            stop_replication(DocId);
         <<"triggered">> ->
-            maybe_start_replication(JsonRepDoc);
+            maybe_start_replication(DocId, JsonRepDoc);
         undefined ->
-            case couch_util:get_value(<<"replication_id">>, RepProps) of
-            undefined ->
-                maybe_start_replication(JsonRepDoc);
-            _ ->
-                ok
-            end
+            maybe_start_replication(DocId, JsonRepDoc);
+        _ ->
+            ?LOG_ERROR("Invalid value for the `state` property of the "
+                "replication document `~s`", [DocId])
         end
     end,
     ok.
@@ -187,26 +185,33 @@ rep_user_ctx({RepDoc}) ->
     end.
 
 
-maybe_start_replication({RepProps} = JsonRepDoc) ->
+maybe_start_replication(DocId, JsonRepDoc) ->
     UserCtx = rep_user_ctx(JsonRepDoc),
-    RepId = couch_rep:make_replication_id(JsonRepDoc, UserCtx),
-    DocId = couch_util:get_value(<<"_id">>, RepProps),
-    case ets:lookup(?REP_ID_TO_DOC_ID_MAP, RepId) of
+    {BaseId, _} = RepId = couch_rep:make_replication_id(JsonRepDoc, UserCtx),
+    case ets:lookup(?REP_ID_TO_DOC_ID_MAP, BaseId) of
     [] ->
-        true = ets:insert(?REP_ID_TO_DOC_ID_MAP, {RepId, DocId}),
+        true = ets:insert(?REP_ID_TO_DOC_ID_MAP, {BaseId, DocId}),
         true = ets:insert(?DOC_TO_REP_ID_MAP, {DocId, RepId}),
         spawn_link(fun() -> start_replication(JsonRepDoc, RepId, UserCtx) end);
-    [{RepId, DocId}] ->
+    [{BaseId, DocId}] ->
+        ok;
+    [{BaseId, OtherDocId}] ->
+        maybe_tag_rep_doc(DocId, JsonRepDoc, ?l2b(BaseId), OtherDocId)
+    end.
+
+
+maybe_tag_rep_doc(DocId, {Props} = JsonRepDoc, RepId, OtherDocId) ->
+    case couch_util:get_value(<<"replication_id">>, Props) of
+    RepId ->
         ok;
-    [{RepId, OtherDocId}] ->
+    _ ->
         ?LOG_INFO("The replication specified by the document `~s` was already"
             " triggered by the document `~s`", [DocId, OtherDocId]),
-        couch_rep:update_rep_doc(
-            JsonRepDoc, [{<<"replication_id">>, ?l2b(element(1, RepId))}]
-        )
+        couch_rep:update_rep_doc(JsonRepDoc, [{<<"replication_id">>, RepId}])
     end.
 
 
+
 start_replication({RepProps} = RepDoc, {Base, Ext} = RepId, UserCtx) ->
     case (catch couch_rep:start_replication(RepDoc, RepId, UserCtx)) of
     RepPid when is_pid(RepPid) ->
@@ -224,16 +229,31 @@ start_replication({RepProps} = RepDoc, {Base, Ext} = RepId, UserCtx) ->
         ?LOG_ERROR("Error starting replication ~p: ~p", [RepId, Error])
     end.
 
+rep_doc_deleted(DocId) ->
+    case stop_replication(DocId) of
+    {ok, {Base, Ext}} ->
+        ?LOG_INFO("Stopped replication `~s` because replication document `~s`"
+            " was deleted", [Base ++ Ext, DocId]);
+    none ->
+        ok
+    end.
 
-maybe_stop_replication({RepProps}) ->
-    DocId = couch_util:get_value(<<"_id">>, RepProps),
+replication_complete(DocId) ->
+    case stop_replication(DocId) of
+    {ok, {Base, Ext}} ->
+        ?LOG_INFO("Replication `~s` finished (triggered by document `~s`)",
+            [Base ++ Ext, DocId]);
+    none ->
+        ok
+    end.
+
+stop_replication(DocId) ->
     case ets:lookup(?DOC_TO_REP_ID_MAP, DocId) of
-    [{DocId, {Base, Ext} = RepId}] ->
+    [{DocId, {BaseId, _} = RepId}] ->
         couch_rep:end_replication(RepId),
-        true = ets:delete(?REP_ID_TO_DOC_ID_MAP, RepId),
+        true = ets:delete(?REP_ID_TO_DOC_ID_MAP, BaseId),
         true = ets:delete(?DOC_TO_REP_ID_MAP, DocId),
-        ?LOG_INFO("Stopped replication `~s` because replication document `~s`"
-            " was deleted", [Base ++ Ext, DocId]);
+        {ok, RepId};
     [] ->
-        ok
+        none
     end.
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