From e8c43b1e8e6f5393e579ae9e015c5b7c282dbf2a Mon Sep 17 00:00:00 2001
From: Adam Kocoloski <adam@cloudant.com>
Date: Wed, 9 Jun 2010 14:02:21 -0400
Subject: rewrite fabric_db_info

---
 src/fabric.erl         |   6 +--
 src/fabric_db_info.erl | 124 +++++++++++++++++--------------------------------
 2 files changed, 45 insertions(+), 85 deletions(-)

diff --git a/src/fabric.erl b/src/fabric.erl
index 80646561..e4887953 100644
--- a/src/fabric.erl
+++ b/src/fabric.erl
@@ -1,7 +1,7 @@
 -module(fabric).
 
 % DBs
--export([all_dbs/0, all_dbs/1, create_db/2, delete_db/2, get_db_info/2,
+-export([all_dbs/0, all_dbs/1, create_db/2, delete_db/2, get_db_info/1,
     get_doc_count/1]).
 
 % Documents
@@ -29,8 +29,8 @@ all_dbs() ->
 all_dbs(Customer) ->
     fabric_all_databases:all_databases(Customer).
 
-get_db_info(DbName, Customer) ->
-    fabric_db_info:get_db_info(dbname(DbName), Customer).
+get_db_info(DbName) ->
+    fabric_db_info:go(dbname(DbName)).
 
 get_doc_count(DbName) ->
     fabric_db_doc_count:go(dbname(DbName)).
diff --git a/src/fabric_db_info.erl b/src/fabric_db_info.erl
index e70b335c..8db7212f 100644
--- a/src/fabric_db_info.erl
+++ b/src/fabric_db_info.erl
@@ -1,91 +1,51 @@
 -module(fabric_db_info).
--author(brad@cloudant.com).
 
--export([get_db_info/2]).
+-export([go/1]).
 
 -include("fabric.hrl").
 
-%% @doc get database information tuple
-get_db_info(DbName, Customer) ->
-    Name = cloudant_db_name(Customer, DbName),
+go(DbName) ->
     Shards = partitions:all_parts(DbName),
     Workers = fabric_util:submit_jobs(Shards, get_db_info, []),
-    Acc0 = {false, length(Workers), lists:usort([ {Beg, nil} ||
-        #shard{range=[Beg,_]} <- Workers])},
-    case fabric_util:recv(Workers, #shard.ref, fun handle_info_msg/3, Acc0) of
-    {ok, ShardInfos} ->
-        {ok, process_infos(ShardInfos, [{db_name, Name}])};
-    Error -> Error
-    end.
-
-
-%% =====================
-%%   internal
-%% =====================
-
-handle_info_msg(_, _, {true, _, Infos0}) ->
-    {stop, Infos0};
-handle_info_msg(_, _, {false, 1, Infos0}) ->
-    MissingShards = lists:reverse(lists:foldl(fun
-        ({S,nil}, Acc) -> [S|Acc];
-        (_, Acc) -> Acc
-    end, [], Infos0)),
-    ?LOG_ERROR("get_db_info error, missing shards: ~p", [MissingShards]),
-    {error, get_db_info};
-handle_info_msg({ok, Info}, #shard{range=[Beg,_]}, {false, N, Infos0}) ->
-    case couch_util:get_value(Beg, Infos0) of
+    Acc0 = {fabric_dict:init(Workers, nil), []},
+    fabric_util:recv(Workers, #shard.ref, fun handle_message/3, Acc0).
+
+handle_message({ok, Info}, #shard{dbname=Name} = Shard, {Counters, Acc}) ->
+    case fabric_dict:lookup_element(Shard, Counters) of
+    undefined ->
+        % already heard from someone else in this range
+        {ok, {Counters, Acc}};
     nil ->
-        Infos = lists:keyreplace(Beg, 1, Infos0, {Beg, Info}),
-        case is_complete(Infos) of
-        true -> {ok, {true, N-1, Infos}};
-        false -> {ok, {false, N-1, Infos}}
-        end;
-    _ ->
-        {ok, {false, N-1, Infos0}}
+        C1 = fabric_dict:store(Shard, ok, Counters),
+        C2 = fabric_view:remove_overlapping_shards(Shard, C1),
+        case fabric_dict:any(nil, C2) of
+        true ->
+            {ok, {C2, [Info|Acc]}};
+        false ->
+            {stop, [{db_name,Name}|merge_results(lists:flatten([Info|Acc]))]}
+        end
     end;
-handle_info_msg(_Other, _, {Complete, N, Infos0}) ->
-    {ok, {Complete, N-1, Infos0}}.
-
-is_complete(List) ->
-    not lists:any(fun({_,Info}) -> Info =:= nil end, List).
-
-cloudant_db_name(Customer, FullName) ->
-    case Customer of
-    "" -> FullName;
-    Name -> re:replace(FullName, [Name,"/"], "", [{return, binary}])
-    end.
-
-%% Loop through Tasks on the flattened Infos and get the aggregated result
-process_infos(Infos, Initial) ->
-    Tasks = [
-        {doc_count, fun sum/2, 0},
-        {doc_del_count, fun sum/2, 0},
-        {update_seq, fun max/2, 1},
-        {purge_seq, fun sum/2, 0},
-        {compact_running, fun bool/2, 0},
-        {disk_size, fun sum/2, 0},
-        {instance_start_time, fun(_, _) -> <<"0">> end, 0},
-        {disk_format_version, fun max/2, 0}],
-
-    Infos1 = lists:flatten(Infos),
-
-    Result = lists:map(fun({Type, Fun, Default}) ->
-        {Type, process_info(Type, Fun, Default, Infos1)}
-    end, Tasks),
-    lists:flatten([Initial, Result]).
-
- process_info(Type, Fun, Default, List) ->
-     lists:foldl(fun(V, AccIn) -> Fun(V, AccIn) end, Default,
-         proplists:get_all_values(Type, List)).
-
-sum(New, Existing) ->
-    New + Existing.
-
-bool(New, Existing) ->
-    New andalso Existing.
-
-max(New, Existing) ->
-    case New > Existing of
-        true  -> New;
-        false -> Existing
-    end.
+handle_message(_, _, Acc) ->
+    {ok, Acc}.
+
+merge_results(Info) ->
+    Dict = lists:foldl(fun({K,V},D0) -> orddict:append(K,V,D0) end,
+        orddict:new(), Info),
+    orddict:fold(fun
+        (doc_count, X, Acc) ->
+            [{doc_count, lists:sum(X)} | Acc];
+        (doc_del_count, X, Acc) ->
+            [{doc_del_count, lists:sum(X)} | Acc];
+        (update_seq, X, Acc) ->
+            [{update_seq, lists:sum(X)} | Acc];
+        (purge_seq, X, Acc) ->
+            [{purge_seq, lists:sum(X)} | Acc];
+        (compact_running, X, Acc) ->
+            [{compact_running, lists:member(true, X)} | Acc];
+        (disk_size, X, Acc) ->
+            [{disk_size, lists:sum(X)} | Acc];
+        (disk_format_version, X, Acc) ->
+            [{disk_format_version, lists:max(X)} | Acc];
+        (_, _, Acc) ->
+            Acc
+    end, [{instance_start_time, <<"0">>}], Dict).
-- 
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