Implement fabric2_db EPI plugin

This mostly equivalent to the `couch_db` EPI plugin, but using fabric2 calls
and without some of the functions that are not relevant to FDB such as
on_compact/1 and others.

7 files changed, 269 insertions, 46 deletions

diff --git a/rel/apps/couch_epi.config b/rel/apps/couch_epi.config
index a53721a48..0f3d2da55 100644
--- a/rel/apps/couch_epi.config
+++ b/rel/apps/couch_epi.config
@@ -12,6 +12,7 @@
 
 {plugins, [
     couch_db_epi,
+    fabric2_epi,
     chttpd_epi,
     couch_index_epi,
     dreyfus_epi,
diff --git a/src/chttpd/src/chttpd_db.erl b/src/chttpd/src/chttpd_db.erl
index 785ca3fc4..dbb92fa84 100644
--- a/src/chttpd/src/chttpd_db.erl
+++ b/src/chttpd/src/chttpd_db.erl
@@ -1047,7 +1047,7 @@ db_doc_req(#httpd{method='GET', mochi_req=MochiReq}=Req, Db, DocId) ->
 
 db_doc_req(#httpd{method='POST', user_ctx=Ctx}=Req, Db, DocId) ->
     couch_httpd:validate_referer(Req),
-    couch_doc:validate_docid(DocId, fabric2_db:name(Db)),
+    fabric2_db:validate_docid(DocId),
     chttpd:validate_ctype(Req, "multipart/form-data"),
 
     Options = [{user_ctx,Ctx}],
@@ -1107,7 +1107,7 @@ db_doc_req(#httpd{method='PUT', user_ctx=Ctx}=Req, Db, DocId) ->
         update_type = UpdateType
     } = parse_doc_query(Req),
     DbName = fabric2_db:name(Db),
-    couch_doc:validate_docid(DocId, fabric2_db:name(Db)),
+    fabric2_db:validate_docid(DocId),
 
     Options = [{user_ctx, Ctx}],
 
@@ -1668,7 +1668,7 @@ db_attachment_req(#httpd{method=Method}=Req, Db, DocId, FileNameParts)
                 % check for the existence of the doc to handle the 404 case.
                 couch_doc_open(Db, DocId, nil, [])
             end,
-            couch_doc:validate_docid(DocId, fabric2_db:name(Db)),
+            fabric2_db:validate_docid(DocId),
             #doc{id=DocId};
         Rev ->
             case fabric2_db:open_doc_revs(Db, DocId, [Rev], [{user_ctx,Ctx}]) of
@@ -2031,7 +2031,7 @@ bulk_get_open_doc_revs1(Db, Props, Options, {}) ->
             {null, {error, Error}, Options};
         DocId ->
             try
-                couch_doc:validate_docid(DocId, fabric2_db:name(Db)),
+                fabric2_db:validate_docid(DocId),
                 bulk_get_open_doc_revs1(Db, Props, Options, {DocId})
             catch throw:{Error, Reason} ->
                 {DocId, {error, {null, Error, Reason}}, Options}
diff --git a/src/fabric/src/fabric.app.src b/src/fabric/src/fabric.app.src
index 20fbb1e2a..77260f962 100644
--- a/src/fabric/src/fabric.app.src
+++ b/src/fabric/src/fabric.app.src
@@ -21,6 +21,7 @@
         kernel,
         stdlib,
         config,
+        couch_epi,
         couch,
         rexi,
         mem3,
diff --git a/src/fabric/src/fabric2_db.erl b/src/fabric/src/fabric2_db.erl
index c926da9e0..2afb780fa 100644
--- a/src/fabric/src/fabric2_db.erl
+++ b/src/fabric/src/fabric2_db.erl
@@ -85,7 +85,7 @@
     %% get_minimum_purge_seq/1,
     %% purge_client_exists/3,
 
-    %% validate_docid/2,
+    validate_docid/1,
     %% doc_from_json_obj_validate/2,
 
     update_doc/2,
@@ -118,9 +118,9 @@
     %% wait_for_compaction/1,
     %% wait_for_compaction/2,
 
-    %% dbname_suffix/1,
-    %% normalize_dbname/1,
-    %% validate_dbname/1,
+    dbname_suffix/1,
+    normalize_dbname/1,
+    validate_dbname/1,
 
     %% make_doc/5,
     new_revid/2
@@ -141,21 +141,26 @@
 
 
 create(DbName, Options) ->
-    Result = fabric2_fdb:transactional(DbName, Options, fun(TxDb) ->
-        case fabric2_fdb:exists(TxDb) of
-            true ->
-                {error, file_exists};
-            false ->
-                fabric2_fdb:create(TxDb, Options)
-        end
-    end),
-    % We cache outside of the transaction so that we're sure
-    % that the transaction was committed.
-    case Result of
-        #{} = Db0 ->
-            Db1 = maybe_add_sys_db_callbacks(Db0),
-            ok = fabric2_server:store(Db1),
-            {ok, Db1#{tx := undefined}};
+    case validate_dbname(DbName) of
+        ok ->
+            Result = fabric2_fdb:transactional(DbName, Options, fun(TxDb) ->
+                case fabric2_fdb:exists(TxDb) of
+                    true ->
+                        {error, file_exists};
+                    false ->
+                        fabric2_fdb:create(TxDb, Options)
+                end
+            end),
+            % We cache outside of the transaction so that we're sure
+            % that the transaction was committed.
+            case Result of
+                #{} = Db0 ->
+                    Db1 = maybe_add_sys_db_callbacks(Db0),
+                    ok = fabric2_server:store(Db1),
+                    {ok, Db1#{tx := undefined}};
+                Error ->
+                    Error
+            end;
         Error ->
             Error
     end.
@@ -225,11 +230,15 @@ list_dbs(UserFun, UserAcc0, Options) ->
 
 
 is_admin(Db) ->
-    % TODO: Need to re-consider couch_db_plugin:check_is_admin/1
-    {SecProps} = get_security(Db),
-    UserCtx = get_user_ctx(Db),
-    {Admins} = get_admins(SecProps),
-    is_authorized(Admins, UserCtx).
+    case fabric2_db_plugin:check_is_admin(Db) of
+        true ->
+            true;
+        false ->
+            {SecProps} = get_security(Db),
+            UserCtx = get_user_ctx(Db),
+            {Admins} = get_admins(SecProps),
+            is_authorized(Admins, UserCtx)
+    end.
 
 
 check_is_admin(Db) ->
@@ -582,6 +591,44 @@ get_missing_revs(Db, JsonIdRevs) ->
     {ok, AllMissing}.
 
 
+validate_docid(<<"">>) ->
+    throw({illegal_docid, <<"Document id must not be empty">>});
+validate_docid(<<"_design/">>) ->
+    throw({illegal_docid, <<"Illegal document id `_design/`">>});
+validate_docid(<<"_local/">>) ->
+    throw({illegal_docid, <<"Illegal document id `_local/`">>});
+validate_docid(Id) when is_binary(Id) ->
+    MaxLen = case config:get("couchdb", "max_document_id_length", "infinity") of
+        "infinity" -> infinity;
+        IntegerVal -> list_to_integer(IntegerVal)
+    end,
+    case MaxLen > 0 andalso byte_size(Id) > MaxLen of
+        true -> throw({illegal_docid, <<"Document id is too long">>});
+        false -> ok
+    end,
+    case couch_util:validate_utf8(Id) of
+        false -> throw({illegal_docid, <<"Document id must be valid UTF-8">>});
+        true -> ok
+    end,
+    case Id of
+    <<?DESIGN_DOC_PREFIX, _/binary>> -> ok;
+    <<?LOCAL_DOC_PREFIX, _/binary>> -> ok;
+    <<"_", _/binary>> ->
+        case fabric2_db_plugin:validate_docid(Id) of
+            true ->
+                ok;
+            false ->
+                throw(
+                  {illegal_docid,
+                   <<"Only reserved document ids may start with underscore.">>})
+        end;
+    _Else -> ok
+    end;
+validate_docid(Id) ->
+    couch_log:debug("Document id is not a string: ~p", [Id]),
+    throw({illegal_docid, <<"Document id must be a string">>}).
+
+
 update_doc(Db, Doc) ->
     update_doc(Db, Doc, []).
 
@@ -758,6 +805,38 @@ fold_changes(Db, SinceSeq, UserFun, UserAcc, Options) ->
     end).
 
 
+dbname_suffix(DbName) ->
+    filename:basename(normalize_dbname(DbName)).
+
+
+normalize_dbname(DbName) ->
+    % Remove in the final cleanup. We don't need to handle shards prefix or
+    % remove .couch suffixes anymore. Keep it for now to pass all the existing
+    % tests.
+    couch_db:normalize_dbname(DbName).
+
+
+validate_dbname(DbName) when is_list(DbName) ->
+    validate_dbname(?l2b(DbName));
+
+validate_dbname(DbName) when is_binary(DbName) ->
+    Normalized = normalize_dbname(DbName),
+    fabric2_db_plugin:validate_dbname(
+        DbName, Normalized, fun validate_dbname_int/2).
+
+validate_dbname_int(DbName, Normalized) when is_binary(DbName) ->
+    DbNoExt = couch_util:drop_dot_couch_ext(DbName),
+    case re:run(DbNoExt, ?DBNAME_REGEX, [{capture,none}, dollar_endonly]) of
+        match ->
+            ok;
+        nomatch ->
+            case is_system_db_name(Normalized) of
+                true -> ok;
+                false -> {error, {illegal_database_name, DbName}}
+            end
+    end.
+
+
 maybe_add_sys_db_callbacks(Db) ->
     IsReplicatorDb = is_replicator_db(Db),
     IsUsersDb = is_users_db(Db),
@@ -1030,16 +1109,13 @@ find_possible_ancestors(RevInfos, MissingRevs) ->
 
 
 apply_before_doc_update(Db, Docs, Options) ->
-    #{before_doc_update := BDU} = Db,
     UpdateType = case lists:member(replicated_changes, Options) of
         true -> replicated_changes;
         false -> interactive_edit
     end,
-    if BDU == undefined -> Docs; true ->
-        lists:map(fun(Doc) ->
-            BDU(Doc, Db, UpdateType)
-        end, Docs)
-    end.
+    lists:map(fun(Doc) ->
+        fabric2_db_plugin:before_doc_update(Db, Doc, UpdateType)
+    end, Docs).
 
 
 update_doc_int(#{} = Db, #doc{} = Doc, Options) ->
diff --git a/src/fabric/src/fabric2_db_plugin.erl b/src/fabric/src/fabric2_db_plugin.erl
new file mode 100644
index 000000000..41f9e9db6
--- /dev/null
+++ b/src/fabric/src/fabric2_db_plugin.erl
@@ -0,0 +1,92 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+%   http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(fabric2_db_plugin).
+
+-export([
+    validate_dbname/3,
+    before_doc_update/3,
+    after_doc_read/2,
+    validate_docid/1,
+    check_is_admin/1,
+    is_valid_purge_client/2
+]).
+
+-define(SERVICE_ID, fabric2_db).
+
+
+%% ------------------------------------------------------------------
+%% API Function Definitions
+%% ------------------------------------------------------------------
+
+validate_dbname(DbName, Normalized, Default) ->
+    maybe_handle(validate_dbname, [DbName, Normalized], Default).
+
+
+before_doc_update(Db, Doc0, UpdateType) ->
+    Fun = fabric2_db:get_before_doc_update_fun(Db),
+    case with_pipe(before_doc_update, [Doc0, Db, UpdateType]) of
+        [Doc1, _Db, UpdateType1] when is_function(Fun) ->
+            Fun(Doc1, Db, UpdateType1);
+        [Doc1, _Db, _UpdateType] ->
+            Doc1
+    end.
+
+
+after_doc_read(Db, Doc0) ->
+    Fun = fabric2_db:get_after_doc_read_fun(Db),
+    case with_pipe(after_doc_read, [Doc0, Db]) of
+        [Doc1, _Db] when is_function(Fun) -> Fun(Doc1, Db);
+        [Doc1, _Db] -> Doc1
+    end.
+
+
+validate_docid(Id) ->
+    Handle = couch_epi:get_handle(?SERVICE_ID),
+    %% callbacks return true only if it specifically allow the given Id
+    couch_epi:any(Handle, ?SERVICE_ID, validate_docid, [Id], []).
+
+
+check_is_admin(Db) ->
+    Handle = couch_epi:get_handle(?SERVICE_ID),
+    %% callbacks return true only if it specifically allow the given Id
+    R = couch_epi:any(Handle, ?SERVICE_ID, check_is_admin, [Db], []),
+    %io:format(standard_error, "~n FFFFFFF ~p check_is_admin Db:~p => ~p~n", [?MODULE, fabric2_db:name(Db), R]),
+    R.
+
+
+is_valid_purge_client(DbName, Props) ->
+    Handle = couch_epi:get_handle(?SERVICE_ID),
+    %% callbacks return true only if it specifically allow the given Id
+    couch_epi:any(Handle, ?SERVICE_ID, is_valid_purge_client, [DbName, Props], []).
+
+%% ------------------------------------------------------------------
+%% Internal Function Definitions
+%% ------------------------------------------------------------------
+
+with_pipe(Func, Args) ->
+    do_apply(Func, Args, [pipe]).
+
+do_apply(Func, Args, Opts) ->
+    Handle = couch_epi:get_handle(?SERVICE_ID),
+    couch_epi:apply(Handle, ?SERVICE_ID, Func, Args, Opts).
+
+maybe_handle(Func, Args, Default) ->
+    Handle = couch_epi:get_handle(?SERVICE_ID),
+    case couch_epi:decide(Handle, ?SERVICE_ID, Func, Args, []) of
+       no_decision when is_function(Default) ->
+           apply(Default, Args);
+       no_decision ->
+           Default;
+       {decided, Result} ->
+           Result
+    end.
diff --git a/src/fabric/src/fabric2_epi.erl b/src/fabric/src/fabric2_epi.erl
new file mode 100644
index 000000000..f73eeb0d2
--- /dev/null
+++ b/src/fabric/src/fabric2_epi.erl
@@ -0,0 +1,48 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+% http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(fabric2_epi).
+
+-behaviour(couch_epi_plugin).
+
+-export([
+    app/0,
+    providers/0,
+    services/0,
+    data_subscriptions/0,
+    data_providers/0,
+    processes/0,
+    notify/3
+]).
+
+app() ->
+    fabric.
+
+providers() ->
+    [].
+
+services() ->
+    [
+        {fabric2_db, fabric2_db_plugin}
+    ].
+
+data_subscriptions() ->
+    [].
+
+data_providers() ->
+    [].
+
+processes() ->
+    [].
+
+notify(_Key, _Old, _New) ->
+    ok.
diff --git a/src/fabric/src/fabric2_sup.erl b/src/fabric/src/fabric2_sup.erl
index 73c6c1f4d..402474c32 100644
--- a/src/fabric/src/fabric2_sup.erl
+++ b/src/fabric/src/fabric2_sup.erl
@@ -29,19 +29,24 @@ start_link(Args) ->
 
 
 init([]) ->
-    Flags = #{
-        strategy => one_for_one,
-        intensity => 1,
-        period => 5
-    },
+    Flags = {one_for_one, 1, 5},
     Children = [
-        #{
-            id => fabric2_server,
-            start => {fabric2_server, start_link, []}
+        {
+            fabric2_server,
+            {fabric2_server, start_link, []},
+            permanent,
+            5000,
+            worker,
+            [fabric2_server]
         },
-        #{
-            id => fabric2_txids,
-            start => {fabric2_txids, start_link, []}
+        {
+            fabric2_txids,
+            {fabric2_txids, start_link, []},
+            permanent,
+            5000,
+            worker,
+            [fabric2_server]
         }
     ],
-    {ok, {Flags, Children}}.
+    ChildrenWithEpi = couch_epi:register_service(fabric2_epi, Children),
+    {ok, {Flags, ChildrenWithEpi}}.