Merge pull request #1369 from apache/COUCHDB-3326-clustered-purge-pr4-on-compact-plugin

[4/5] Clustered Purge: Add on_compact EPI hook

3 files changed, 37 insertions, 1 deletions

diff --git a/src/couch/src/couch_bt_engine_compactor.erl b/src/couch/src/couch_bt_engine_compactor.erl
index 4e52064b4..2c5b78e0b 100644
--- a/src/couch/src/couch_bt_engine_compactor.erl
+++ b/src/couch/src/couch_bt_engine_compactor.erl
@@ -44,6 +44,8 @@ start(#st{} = St, DbName, Options, Parent) ->
     } = St,
     couch_log:debug("Compaction process spawned for db \"~s\"", [DbName]),
 
+    couch_db_engine:trigger_on_compact(DbName),
+
     {ok, NewSt, DName, DFd, MFd, Retry} =
             open_compaction_files(Header, FilePath, Options),
     erlang:monitor(process, MFd),
diff --git a/src/couch/src/couch_db_engine.erl b/src/couch/src/couch_db_engine.erl
index 49742012d..2fe0b0d9d 100644
--- a/src/couch/src/couch_db_engine.erl
+++ b/src/couch/src/couch_db_engine.erl
@@ -627,7 +627,8 @@
     count_changes_since/2,
 
     start_compaction/1,
-    finish_compaction/2
+    finish_compaction/2,
+    trigger_on_compact/1
 ]).
 
 
@@ -891,3 +892,31 @@ finish_compaction(Db, CompactInfo) ->
     end,
     ok = gen_server:call(couch_server, {db_updated, NewDb}, infinity),
     {ok, NewDb}.
+
+
+trigger_on_compact(DbName) ->
+    {ok, DDocs} = get_ddocs(DbName),
+    couch_db_plugin:on_compact(DbName, DDocs).
+
+
+get_ddocs(<<"shards/", _/binary>> = DbName) ->
+    {_, Ref} = spawn_monitor(fun() ->
+        exit(fabric:design_docs(mem3:dbname(DbName)))
+    end),
+    receive
+        {'DOWN', Ref, _, _, {ok, JsonDDocs}} ->
+            {ok, lists:map(fun(JsonDDoc) ->
+                couch_doc:from_json_obj(JsonDDoc)
+            end, JsonDDocs)};
+        {'DOWN', Ref, _, _, Else} ->
+            Else
+    end;
+get_ddocs(DbName) ->
+    couch_util:with_db(DbName, fun(Db) ->
+        FoldFun = fun(FDI, Acc) ->
+            Doc = couch_db:open_doc_int(Db, FDI, []),
+            {ok, [Doc | Acc]}
+        end,
+        {ok, Docs} = couch_db:fold_design_docs(Db, FoldFun, [], []),
+        {ok, lists:reverse(Docs)}
+    end).
diff --git a/src/couch/src/couch_db_plugin.erl b/src/couch/src/couch_db_plugin.erl
index 740b8121b..816325699 100644
--- a/src/couch/src/couch_db_plugin.erl
+++ b/src/couch/src/couch_db_plugin.erl
@@ -18,6 +18,7 @@
     after_doc_read/2,
     validate_docid/1,
     check_is_admin/1,
+    on_compact/2,
     on_delete/2
 ]).
 
@@ -56,6 +57,10 @@ check_is_admin(Db) ->
     %% callbacks return true only if it specifically allow the given Id
     couch_epi:any(Handle, ?SERVICE_ID, check_is_admin, [Db], []).
 
+on_compact(DbName, DDocs) ->
+    Handle = couch_epi:get_handle(?SERVICE_ID),
+    couch_epi:apply(Handle, ?SERVICE_ID, on_compact, [DbName, DDocs], []).
+
 on_delete(DbName, Options) ->
     Handle = couch_epi:get_handle(?SERVICE_ID),
     couch_epi:apply(Handle, ?SERVICE_ID, on_delete, [DbName, Options], []).