From 0fc0c2d630abe0f4b6cc37c7f92728d1fe156ff3 Mon Sep 17 00:00:00 2001
From: John Christopher Anderson <jchris@apache.org>
Date: Fri, 29 Jan 2010 20:08:54 +0000
Subject: Thanks Filipe Manana. Closes COUCHDB-631.

Replicator option to replicate a list of docids (bypasses by_seq index).

Usage: POST to /_replicate with a JSON body of:

{"source": "myfoo",
"target" : "http://remotedb.com/theirfoo",
"doc_ids": ["foo1", "foo3", "foo666"]}

This will copy the listed docs from the source to the target database.

git-svn-id: https://svn.apache.org/repos/asf/couchdb/trunk@904615 13f79535-47bb-0310-9956-ffa450edef68
---
 src/couchdb/couch_rep.erl | 83 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 64 insertions(+), 19 deletions(-)

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

diff --git a/src/couchdb/couch_rep.erl b/src/couchdb/couch_rep.erl
index 98413f23..c182c001 100644
--- a/src/couchdb/couch_rep.erl
+++ b/src/couchdb/couch_rep.erl
@@ -45,7 +45,8 @@
     complete = false,
     committed_seq = 0,
 
-    stats = nil
+    stats = nil,
+    doc_ids = nil
 }).
 
 %% convenience function to do a simple replication from the shell
@@ -102,26 +103,49 @@ do_init([RepId, {PostProps}, UserCtx] = InitArgs) ->
     SourceProps = proplists:get_value(<<"source">>, PostProps),
     TargetProps = proplists:get_value(<<"target">>, PostProps),
 
+    DocIds = proplists:get_value(<<"doc_ids">>, PostProps, nil),
     Continuous = proplists:get_value(<<"continuous">>, PostProps, false),
     CreateTarget = proplists:get_value(<<"create_target">>, PostProps, false),
 
     Source = open_db(SourceProps, UserCtx),
     Target = open_db(TargetProps, UserCtx, CreateTarget),
 
-    SourceLog = open_replication_log(Source, RepId),
-    TargetLog = open_replication_log(Target, RepId),
-
     SourceInfo = dbinfo(Source),
     TargetInfo = dbinfo(Target),
+
+    case DocIds of
+    List when is_list(List) ->
+        % Fast replication using only a list of doc IDs to replicate.
+        % Replication sessions, checkpoints and logs are not created
+        % since the update sequence number of the source DB is not used
+        % for determining which documents are copied into the target DB.
+        SourceLog = nil,
+        TargetLog = nil,
+
+        StartSeq = nil,
+        History = nil,
+
+        ChangesFeed = nil,
+        MissingRevs = nil,
+
+        {ok, Reader} =
+        couch_rep_reader:start_link(self(), Source, DocIds, PostProps);
+
+    _ ->
+        % Replication using the _changes API (DB sequence update numbers).
+        SourceLog = open_replication_log(Source, RepId),
+        TargetLog = open_replication_log(Target, RepId),
     
-    {StartSeq, History} = compare_replication_logs(SourceLog, TargetLog),
-
-    {ok, ChangesFeed} =
-    couch_rep_changes_feed:start_link(self(), Source, StartSeq, PostProps),
-    {ok, MissingRevs} =
-    couch_rep_missing_revs:start_link(self(), Target, ChangesFeed, PostProps),
-    {ok, Reader} =
-    couch_rep_reader:start_link(self(), Source, MissingRevs, PostProps),
+        {StartSeq, History} = compare_replication_logs(SourceLog, TargetLog),
+
+        {ok, ChangesFeed} =
+        couch_rep_changes_feed:start_link(self(), Source, StartSeq, PostProps),
+        {ok, MissingRevs} =
+        couch_rep_missing_revs:start_link(self(), Target, ChangesFeed, PostProps),
+        {ok, Reader} =
+        couch_rep_reader:start_link(self(), Source, MissingRevs, PostProps)
+    end,
+
     {ok, Writer} =
     couch_rep_writer:start_link(self(), Target, Reader, PostProps),
 
@@ -156,7 +180,8 @@ do_init([RepId, {PostProps}, UserCtx] = InitArgs) ->
         target_log = TargetLog,
         rep_starttime = httpd_util:rfc1123_date(),
         src_starttime = proplists:get_value(instance_start_time, SourceInfo),
-        tgt_starttime = proplists:get_value(instance_start_time, TargetInfo)
+        tgt_starttime = proplists:get_value(instance_start_time, TargetInfo),
+        doc_ids = DocIds
     },
     {ok, State}.
 
@@ -325,20 +350,34 @@ dbinfo(Db) ->
     {ok, Info} = couch_db:get_db_info(Db),
     Info.
 
+do_terminate(#state{doc_ids=DocIds} = State) when is_list(DocIds) ->
+    #state{
+        listeners = Listeners,
+        rep_starttime = ReplicationStartTime,
+        stats = Stats
+    } = State,
+
+    RepByDocsJson = {[
+        {<<"start_time">>, ?l2b(ReplicationStartTime)},
+        {<<"end_time">>, ?l2b(httpd_util:rfc1123_date())},
+        {<<"docs_read">>, ets:lookup_element(Stats, docs_read, 2)},
+        {<<"docs_written">>, ets:lookup_element(Stats, docs_written, 2)},
+        {<<"doc_write_failures">>,
+            ets:lookup_element(Stats, doc_write_failures, 2)}
+    ]},
+
+    terminate_cleanup(State),
+    [gen_server:reply(L, {ok, RepByDocsJson}) || L <- lists:reverse(Listeners)];
+
 do_terminate(State) ->
     #state{
         checkpoint_history = CheckpointHistory,
         committed_seq = NewSeq,
         listeners = Listeners,
         source = Source,
-        target = Target,
         continuous = Continuous,
-        stats = Stats,
         source_log = #doc{body={OldHistory}}
     } = State,
-    couch_task_status:update("Finishing"),
-    ets:delete(Stats),
-    close_db(Target),
     
     NewRepHistory = case CheckpointHistory of
     nil ->
@@ -366,7 +405,13 @@ do_terminate(State) ->
         false ->
             [gen_server:reply(R, retry) || R <- OtherListeners]
     end,
-    close_db(Source).
+    terminate_cleanup(State).
+
+terminate_cleanup(#state{source=Source, target=Target, stats=Stats}) ->
+    couch_task_status:update("Finishing"),
+    close_db(Target),
+    close_db(Source),
+    ets:delete(Stats).
 
 has_session_id(_SessionId, []) ->
     false;
-- 
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