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27037-6-dynamic-endpoint-handlers #40
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| %% 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. | ||
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| %% @doc link endpoints to callbacks - configs of multiple deps are combined. | ||
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| {docs, clauses, [ | ||
| {"", {chttpd_misc, handle_welcome_req, 1}}, | ||
| {"favicon.ico", {chttpd_misc, handle_favicon_req, 1}}, | ||
| {"_utils", {chttpd_misc, handle_utils_dir_req, 1}}, | ||
| {"_all_dbs", {chttpd_misc, handle_all_dbs_req, 1}}, | ||
| {"_active_tasks", {chttpd_misc, handle_task_status_req, 1}}, | ||
| {"_node", {chttpd_misc, handle_node_req, 1}}, | ||
| {"_reload_query_servers", {chttpd_misc, | ||
| handle_reload_query_servers_req, 1}}, | ||
| {"_replicate", {chttpd_misc, handle_replicate_req, 1}}, | ||
| {"_uuids", {chttpd_misc, handle_uuids_req, 1}}, | ||
| {"_session", {chttpd_auth, handle_session_req, 1}}, | ||
| {"_up", {chttpd_misc, handle_up_req, 1}}, | ||
| {"_user", {chttpd_auth, handle_user_req, 1}}, | ||
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Member
There was a problem hiding this comment. There is no such endpoint "_user" on current master nor such function in chttpd_auth module. |
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| {'_', {chttpd_db, handle_request, 1}} | ||
| ]}. | ||
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| {db, list, [ | ||
| {<<"_view_cleanup">>, {chttpd_db, handle_view_cleanup_req, 2}}, | ||
| {<<"_compact">>, {chttpd_db, handle_compact_req, 2}}, | ||
| {<<"_design">>, {chttpd_db, handle_design_req, 2}}, | ||
| {<<"_temp_view">>, {chttpd_view, handle_temp_view_req, 2}}, | ||
| {<<"_changes">>, {chttpd_db, handle_changes_req, 2}} | ||
| ]}. | ||
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| {design, list, [ | ||
| {<<"_view">>, {chttpd_view, handle_view_req, 3}}, | ||
| {<<"_show">>, {chttpd_show, handle_doc_show_req, 3}}, | ||
| {<<"_list">>, {chttpd_show, handle_view_list_req, 3}}, | ||
| {<<"_update">>, {chttpd_show, handle_doc_update_req, 3}}, | ||
| {<<"_info">>, {chttpd_db, handle_design_info_req, 3}}, | ||
| {<<"_rewrite">>, {chttpd_rewrite, handle_rewrite_req, 3}} | ||
| ]}. | ||
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,246 @@ | ||
| %% 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. | ||
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| %% @doc Configurable, dynamic creation of endpoint handler callback indirections | ||
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| -module(chttpd_handler). | ||
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| -export([url_handler/1, db_url_handlers/0, design_url_handlers/0, | ||
| build/0, build/1]). | ||
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| % debugging | ||
| -export([test_cfg/0]). | ||
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| -vsn(5). | ||
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| %% @doc a complete configuration data set | ||
| -type config() :: [Function::{Name::atom(), clauses|list, [bind()]}]. | ||
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| %% @doc one essential pair of a pattern and the fun to be returned for it | ||
| -type bind() :: {Endpoint::term(), MFA::{atom(), atom(), integer()}}. | ||
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| -spec url_handler(Endpoint::list()) -> Handler::fun(). | ||
| %% @doc Dispatch endpoint to fun, wrapper to hide dynamic module. | ||
| url_handler(Endpoint) -> | ||
| try | ||
| chttpd_dyn_handler:url_handler(Endpoint) | ||
| catch | ||
| _:_ -> | ||
| build(), | ||
| chttpd_dyn_handler:url_handler(Endpoint) | ||
| end. | ||
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| -spec db_url_handlers() -> [{Endpoint::list(), Handler::fun()}]. | ||
| %% @doc Get a list of endpoints and handler funs, wrapper to hide dyn module. | ||
| db_url_handlers() -> | ||
| chttpd_dyn_handler:db_url_handlers(). | ||
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| -spec design_url_handlers() -> [{Endpoint::list(), Handler::fun()}]. | ||
| %% @doc Get a list of endpoints and handler funs, wrapper to hide dyn module. | ||
| design_url_handlers() -> | ||
| chttpd_dyn_handler:design_url_handlers(). | ||
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| -spec build() -> ok | []. | ||
| %% @doc Create the dynamic handler functions from ini file. | ||
| build() -> | ||
| build(load_defs()). | ||
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| -spec build(HandlerCfg::config()) -> ok. | ||
| %% @doc Compile the complete syntax tree, purge and load the dynamic module | ||
| build(Cfg) when is_list(Cfg) -> | ||
| io:format(user, "~n➽ Dynamic handlers using config: ~n~p~n", [Cfg]), | ||
|
Member
There was a problem hiding this comment. Please use |
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| Opts = [verbose, report_errors], | ||
| {ok, Mod, Bin} = compile:forms(forms(chttpd_dyn_handler, Cfg), Opts), | ||
| % don't code:purge(Mod), | ||
| {module, Mod} = code:load_binary(Mod, atom_to_list(Mod) ++ ".erl", Bin), | ||
| ok. | ||
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| -spec load_defs() -> CombinedHandlerCfg::config(). | ||
| %% @doc assemble the configuration from the chttpd_handler.cfg of all apps. | ||
| load_defs() -> | ||
| Apps = application:loaded_applications(), | ||
| io:format(user, "~n➽ Dynamic handler module parses these apps' configs: ~n~p~n", [Apps]), | ||
| {AllURLHandlers, AllDBHandlers, AllDesignHandlers} = lists:foldl( | ||
| fun(App, {URLHandlers, DBHandlers, DesignHandlers}) -> | ||
| Defs = load_defs(App), | ||
| {URLHandlers ++ [ B || {docs, clauses, B} <- Defs ], | ||
| DBHandlers ++ [ B || {db, list, B} <- Defs ], | ||
| DesignHandlers ++ [ B || {design, list, B} <- Defs ]} | ||
| end, | ||
| {[],[],[]}, | ||
| [element(1, A) || A <- Apps]), | ||
| [{url_handler, clauses, lists:flatten(AllURLHandlers)}, | ||
| {db_url_handlers, list, lists:flatten(AllDBHandlers)}, | ||
| {design_url_handlers, list, lists:flatten(AllDesignHandlers)}]. | ||
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| -spec load_defs(AppName::atom()) -> OneAppsHandlerCfg::config(). | ||
| %% @doc assemble the configuration from the chttpd_handler.cfg of all apps. | ||
| % load_defs(App) -> | ||
| % [ check_def(test_cfg(), "no path (testing)") ]. | ||
| load_defs(App) -> | ||
| io:format(user, "~n➽ Dynamic handler uses priv dir for ~p: ~p~n", [App, code:priv_dir(App)]), | ||
| case code:priv_dir(App) of | ||
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| {error, _Error} -> | ||
| []; | ||
| Dir -> | ||
| Path = Dir ++ "/chttpd_handler.cfg", | ||
| case file:consult(Path) of | ||
| {ok, Defs} -> | ||
| [ check_def(Def, Path) || Def <- Defs ]; | ||
| {error, _Error} -> | ||
| [] | ||
| end | ||
| end. | ||
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| check_def({_, _, []}=Def, Path) -> | ||
| throw({no_defs_error, Def, Path}); | ||
| check_def({docs, clauses, B}, Path) -> | ||
| {docs, clauses, sort(check_dupes(check_bindings(B, list, 1, Path), Path))}; | ||
| check_def({db, list, B}, Path) -> | ||
| {db, list, check_dupes(check_bindings(B, binary, 2, Path), Path)}; | ||
| check_def({design, list, B}, Path) -> | ||
| {design, list, check_dupes(check_bindings(B, binary, 3, Path), Path)}; | ||
| check_def(Def, Path) -> | ||
| throw({tag_error, Def, Path}). | ||
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| check_bindings([{Endpoint, {M, F, Arity}}=Good | More], list, Arity, Path) | ||
| when is_list(Endpoint), is_atom(M), is_atom(F), is_integer(Arity) -> | ||
| [Good | check_bindings(More, list, Arity, Path)]; | ||
| check_bindings([{Endpoint, {M, F, Arity}}=Good | More], binary, Arity, Path) | ||
| when is_binary(Endpoint), is_atom(M), is_atom(F), is_integer(Arity) -> | ||
| [Good | check_bindings(More, binary, Arity, Path)]; | ||
| check_bindings([{'_', {M, F, Arity}}=Good | More], Type, Arity, Path) | ||
| when is_atom(M), is_atom(F), is_integer(Arity) -> | ||
| [Good | check_bindings(More, Type, Arity, Path)]; | ||
| check_bindings([Bad | _], _, Arity, Path) -> | ||
| throw({syntax_or_arity_error, Bad, exptected_arity, Arity, Path}); | ||
| check_bindings([], _, _, _) -> | ||
| []. | ||
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| -spec sort(Cfg::config()) -> config(). | ||
| %% @doc make sure that any _ is the last clause of a generated function | ||
| sort(Cfg) -> | ||
| lists:sort( | ||
| fun ({'_',_}, _) -> false; | ||
| (_, {'_',_}) -> true; | ||
| (_, _) -> true | ||
| end, | ||
| Cfg). | ||
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| -spec check_dupes(Cfg::config(), Path::list()) -> config() | []. | ||
| %% @doc crash if an endpoint is defined twice | ||
| check_dupes(Cfg, Path) -> | ||
| lists:sort( | ||
| fun ({E,_}=Def1, {E, _}=Def2) -> | ||
| throw({duplicate_endpoint, E, Def1, Def2, Path}); | ||
| (_, _) -> true | ||
| end, | ||
| Cfg). | ||
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| -spec forms(Mod::atom(), Defs::[bind()]) -> erl_syntax:syntaxTree(). | ||
| %% @doc The complete syntax tree of the dynamic module | ||
| forms(Mod, Defs) -> | ||
| Statements = [ | ||
| module_stmt(Mod), | ||
| export_stmt( | ||
| [{Name, case Lay of clauses -> 1; list -> 0 end} | ||
| || {Name, Lay, _} <- Defs ]) | ||
| | [ binding_function(Name, Lay, Def) || {Name, Lay, Def} <- Defs ]], | ||
| io:format(user, "~n➽ Dynamic handler statement tree: ~n~p~n", [Statements]), | ||
| [ erl_syntax:revert(X) || X <- Statements]. | ||
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| -spec module_stmt(ModuleName::atom()) -> erl_syntax:syntaxTree(). | ||
| %% @doc Create syntax tree for the module statement of the dynamic module | ||
| module_stmt(Name) -> | ||
| erl_syntax:attribute( | ||
| erl_syntax:atom(module), | ||
| [erl_syntax:atom(Name)]). | ||
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| -spec export_stmt([Exports::{Name::atom(), Arity::integer()}]) -> | ||
| erl_syntax:syntaxTree(). | ||
| %% @doc Create syntax tree for the export statement of the dynamic module | ||
| export_stmt(Exports) -> | ||
| erl_syntax:attribute( | ||
| erl_syntax:atom(export), | ||
| [erl_syntax:list( | ||
| [ erl_syntax:arity_qualifier( | ||
| erl_syntax:atom(Name), | ||
| erl_syntax:integer(Arity)) | ||
| || {Name, Arity} <- Exports ] | ||
| )]). | ||
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| -spec binding_function(Name::atom(), clauses | list, [bind()]) -> | ||
| erl_syntax:syntaxTree(). | ||
| %% @doc Create syntax subtree for a function that either has multiple clauses | ||
| %% or returns a list of tuples of a tag and a fun. | ||
| %/ binding_function(Name, list, []) -> | ||
| %/ erl_syntax:function( | ||
| %/ erl_syntax:atom(Name), | ||
| %/ [erl_syntax:clause([], none, | ||
| %/ [erl_syntax:list([])])]); | ||
| binding_function(Name, list, Defs) -> | ||
| erl_syntax:function( | ||
| erl_syntax:atom(Name), | ||
| [erl_syntax:clause([], none, | ||
| [erl_syntax:list( | ||
| [erl_syntax:tuple([ | ||
| erl_syntax:abstract(P), | ||
| create_fun(Def)]) | ||
| || {P, Def} <- Defs ])])]); | ||
| binding_function(Name, clauses, []) -> | ||
| io:format(user, "~n➽ Dynamic handler module creates no url handlers.~n", []), | ||
| erl_syntax:function( | ||
| erl_syntax:atom(Name), | ||
| [erl_syntax:clause([erl_syntax:underscore()], none, [erl_syntax:atom(nil)])]); | ||
| binding_function(Name, clauses, Defs) -> | ||
| erl_syntax:function( | ||
| erl_syntax:atom(Name), | ||
| [create_fun_clause(Def) || Def <- sort(Defs)]). | ||
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| -spec create_fun_clause(bind()) -> erl_syntax:syntaxTree(). | ||
| %% @doc Create syntax subtree for a function clause with one implicit fun call. | ||
| create_fun_clause({P, MFA}) -> | ||
| erl_syntax:clause( | ||
| [case P of | ||
| '_' -> erl_syntax:underscore(); | ||
| _ -> erl_syntax:abstract(P) | ||
| end], | ||
| none, | ||
| [create_fun(MFA)]). | ||
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| -spec create_fun(MFA::{Module::atom(), Function::atom(), Arity::integer()}) -> | ||
| erl_syntax:syntaxTree(). | ||
| %% @doc Create syntax subtree for an implicit fun call. | ||
| create_fun({M, F, A}) -> | ||
| erl_syntax:implicit_fun( | ||
| erl_syntax:atom(M), | ||
| erl_syntax:atom(F), | ||
| erl_syntax:integer(A)). | ||
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| test_cfg() -> | ||
| {docs, clauses, [ | ||
| {"", {chttpd_misc, handle_welcome_req, 1}}, | ||
| {"favicon.ico", {chttpd_misc, handle_favicon_req, 1}}, | ||
| {"_utils", {chttpd_misc, handle_utils_dir_req, 1}}, | ||
| {"_all_dbs", {chttpd_misc, handle_all_dbs_req, 1}}, | ||
| {"_active_tasks", {chttpd_misc, handle_task_status_req, 1}}, | ||
| {"_node", {chttpd_misc, handle_node_req, 1}}, | ||
| {"_reload_query_servers", {chttpd_misc, | ||
| handle_reload_query_servers_req, 1}}, | ||
| {"_replicate", {chttpd_misc, handle_replicate_req, 1}}, | ||
| {"_uuids", {chttpd_misc, handle_uuids_req, 1}}, | ||
| {"_session", {chttpd_auth, handle_session_req, 1}}, | ||
| {"_up", {chttpd_misc, handle_up_req, 1}}, | ||
| {"_user", {chttpd_auth, handle_user_req, 1}}, | ||
| {'_', {chttpd_db, handle_request, 1}} | ||
| ]}. | ||
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Why clauses, not list?
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As far as I understood, first element of this config structure defined to what API level following resources are belong: db for /db/:resource, design for /db/_design/ddoc/:resource etc. But why server root level is named as docs then? This causes false assumption that these resources will be available at /db/docid/ level.