[6/6] couchdb-couch-epi git commit: Add couch_epi_data

[rn...@apache.org]

Add couch_epi_data


Project: http://git-wip-us.apache.org/repos/asf/couchdb-couch-epi/repo
Commit: http://git-wip-us.apache.org/repos/asf/couchdb-couch-epi/commit/59bbd8ee
Tree: http://git-wip-us.apache.org/repos/asf/couchdb-couch-epi/tree/59bbd8ee
Diff: http://git-wip-us.apache.org/repos/asf/couchdb-couch-epi/diff/59bbd8ee

Branch: refs/heads/master
Commit: 59bbd8eefbf2d7dc881e6a8b2911a84966be88a4
Parents: 32ba6e7
Author: ILYA Khlopotov <ii...@ca.ibm.com>
Authored: Wed Jun 24 13:52:59 2015 -0700
Committer: ILYA Khlopotov <ii...@ca.ibm.com>
Committed: Wed Jun 24 15:13:50 2015 -0700

----------------------------------------------------------------------
 src/couch_epi_data.erl | 151 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)
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http://git-wip-us.apache.org/repos/asf/couchdb-couch-epi/blob/59bbd8ee/src/couch_epi_data.erl
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diff --git a/src/couch_epi_data.erl b/src/couch_epi_data.erl
new file mode 100644
index 0000000..d421133
--- /dev/null
+++ b/src/couch_epi_data.erl
@@ -0,0 +1,151 @@
+% 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(couch_epi_data).
+
+-behaviour(gen_server).
+
+%% ------------------------------------------------------------------
+%% API Function Exports
+%% ------------------------------------------------------------------
+
+-export([childspec/4]).
+-export([start_link/4, reload/1]).
+-export([wait/1, stop/1]).
+
+%% ------------------------------------------------------------------
+%% gen_server Function Exports
+%% ------------------------------------------------------------------
+
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+         terminate/2, code_change/3]).
+
+-record(state, {
+    subscriber, module, key, hash, handle,
+    initialized = false, pending = []}).
+
+%% ------------------------------------------------------------------
+%% API Function Definitions
+%% ------------------------------------------------------------------
+
+childspec(Id, App, EpiKey, Module) ->
+    {
+        Id,
+        {?MODULE, start_link, [
+            App,
+            EpiKey,
+            Module,
+            []
+        ]},
+        permanent,
+        5000,
+        worker,
+        [Module]
+    }.
+
+start_link(SubscriberApp, {epi_key, Key}, Module, Options) ->
+    gen_server:start_link(?MODULE, [SubscriberApp, Module, Key, Options], []).
+
+reload(Server) ->
+    gen_server:call(Server, reload).
+
+wait(Server) ->
+    gen_server:call(Server, wait).
+
+stop(Server) ->
+    catch gen_server:call(Server, stop).
+
+%% ------------------------------------------------------------------
+%% gen_server Function Definitions
+%% ------------------------------------------------------------------
+
+init([Subscriber, Module, Key, _Options]) ->
+    gen_server:cast(self(), init),
+    {ok, #state{
+        subscriber = Subscriber,
+        module = Module,
+        key = Key,
+        handle = couch_epi_data_gen:get_handle(Key)}}.
+
+handle_call(wait, _From, #state{initialized = true} = State) ->
+    {reply, ok, State};
+handle_call(wait, From, #state{pending = Pending} = State) ->
+    {noreply, State#state{pending = [From | Pending]}};
+handle_call(reload, _From, State) ->
+    {Res, NewState} = reload_if_updated(State),
+    {reply, Res, NewState};
+handle_call(stop, _From, State) ->
+    {stop, normal, State};
+handle_call(_Request, _From, State) ->
+    {reply, ok, State}.
+
+handle_cast(init, #state{pending = Pending} = State) ->
+    {_, NewState} = reload_if_updated(State),
+    [gen_server:reply(Client, ok) || Client <- Pending],
+    {noreply, NewState#state{initialized = true, pending = []}};
+handle_cast(_Msg, State) ->
+    {noreply, State}.
+
+handle_info(_Info, State) ->
+    {noreply, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {_, NewState} = reload_if_updated(State),
+    {ok, NewState}.
+
+%% ------------------------------------------------------------------
+%% Internal Function Definitions
+%% ------------------------------------------------------------------
+
+reload_if_updated(#state{hash = OldHash, module = Module} = State) ->
+    case couch_epi_functions_gen:hash([Module]) of
+        OldHash ->
+            {ok, State};
+        Hash ->
+            safe_set(Hash, State)
+    end.
+
+safe_set(Hash, #state{} = State) ->
+    #state{
+        handle = Handle,
+        subscriber = Subscriber,
+        module = Module,
+        key = Key} = State,
+    try
+        Data = get_from_module(Module),
+        OldData = current(Handle, Subscriber),
+        ok = couch_epi_data_gen:set(Handle, Subscriber, Data),
+        couch_epi_server:notify(Subscriber, Key, {data, OldData}, {data, Data}),
+        {ok, State#state{hash = Hash}}
+    catch Class:Reason ->
+        {{Class, Reason}, State}
+    end.
+
+get_from_module(Module) ->
+    try
+        Module:data()
+    catch
+        error:undef -> []
+    end.
+
+current(Handle, Subscriber) ->
+    try
+        case couch_epi_data_gen:by_source(Handle, Subscriber) of
+            undefined -> [];
+            Data -> Data
+        end
+    catch error:undef ->
+        []
+    end.