[GitHub] davisp commented on a change in pull request #754: Compactor optimization - PR FOR FEEDBACK ONLY

[gi...@git.apache.org]

davisp commented on a change in pull request #754: Compactor optimization - PR FOR FEEDBACK ONLY
URL: https://github.com/apache/couchdb/pull/754#discussion_r133548905
 
 

 ##########
 File path: src/couch/src/couch_db_updater.erl
 ##########
 @@ -1034,56 +1041,90 @@ check_md5(_, _) -> throw(md5_mismatch).
 
 start_copy_compact(#db{}=Db) ->
     erlang:put(io_priority, {db_compact, Db#db.name}),
-    #db{name=Name, filepath=Filepath, options=Options, header=Header} = Db,
-    couch_log:debug("Compaction process spawned for db \"~s\"", [Name]),
+    couch_log:debug("Compaction process spawned for db \"~s\"", [Db#db.name]),
+
+    {ok, InitCompSt} = open_compaction_files(Db),
+
+    Stages = [
+        fun copy_purge_info/1,
+        fun copy_compact/1,
+        fun commit_compaction_data/1,
+        fun sort_meta_data/1,
+        fun commit_compaction_data/1,
+        fun copy_meta_data/1,
+        fun compact_final_sync/1
+    ],
 
-    {ok, NewDb, DName, DFd, MFd, Retry} =
-        open_compaction_files(Name, Header, Filepath, Options),
-    erlang:monitor(process, MFd),
+    FinalCompSt = lists:foldl(fun(Stage, CompSt) ->
+        Stage(CompSt)
+    end, InitCompSt, Stages),
 
-    % This is a bit worrisome. init_db/4 will monitor the data fd
-    % but it doesn't know about the meta fd. For now I'll maintain
-    % that the data fd is the old normal fd and meta fd is special
-    % and hope everything works out for the best.
 
 Review comment:
   Yep, it got moved to clean up start_compact. That comment is way old me. I know how couch_file works better now so the comment can go as its misleading.
 
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