erl: add stop_producer (#39)

Author: alissa-tung

src/x/hstreamdb-erl-nifs/src/lib.rs

@@ -14,12 +14,12 @@ rustler::atoms! {
 
 rustler::init!(
     "hstreamdb",
-    [create_stream, start_producer, append],
+    [create_stream, start_producer, stop_producer, append],
     load = load
 );
 
 #[derive(Clone)]
-pub struct NifAppender(UnboundedSender<Record>);
+pub struct NifAppender(UnboundedSender<Option<Record>>);
 
 fn load(env: Env, _: Term) -> bool {
     resource!(NifAppender, env);
@@ -65,7 +65,7 @@ pub fn start_producer(
     compression_type: Atom,
     flush_settings: Term,
 ) -> ResourceArc<NifAppender> {
-    let (request_sender, request_receiver) = unbounded_channel::<Record>();
+    let (request_sender, request_receiver) = unbounded_channel::<Option<Record>>();
     let compression_type = atom_to_compression_type(compression_type);
     let flush_settings = new_flush_settings(flush_settings);
     let future = async move {
@@ -93,7 +93,10 @@ pub fn start_producer(
             let mut request_receiver = request_receiver;
             let mut appender = appender;
             while let Some(record) = request_receiver.recv().await {
-                _ = appender.append(record).unwrap()
+                match record {
+                    Some(record) => _ = appender.append(record).unwrap(),
+                    None => request_receiver.close(),
+                }
             }
         });
         producer.start().await
@@ -102,14 +105,21 @@ pub fn start_producer(
     ResourceArc::new(NifAppender(request_sender))
 }
 
+#[rustler::nif]
+fn stop_producer(producer: ResourceArc<NifAppender>) -> Atom {
+    let producer = &producer.0;
+    producer.send(None).unwrap();
+    ok()
+}
+
 #[rustler::nif]
 fn append(producer: ResourceArc<NifAppender>, partition_key: String, raw_payload: String) -> Atom {
     let record = Record {
         partition_key,
         payload: hstreamdb::Payload::RawRecord(raw_payload.into_bytes()),
     };
     let producer = &producer.0;
-    producer.send(record).unwrap();
+    producer.send(Some(record)).unwrap();
     ok()
 }
 

x/hstreamdb_erl/src/hstreamdb.erl

@@ -4,7 +4,7 @@
 
 -on_load(init/0).
 
--export([create_stream/5, start_producer/4, append/3]).
+-export([create_stream/5, start_producer/4, stop_producer/1, append/3]).
 
 -export_type([producer/0, compression_type/0]).
 
@@ -36,6 +36,11 @@ create_stream(ServerUrl, StreamName, ReplicationFactor, BacklogDuration, ShardCo
 start_producer(ServerUrl, StreamName, CompressionType, FlushSettings) ->
     none.
 
+-spec stop_producer(
+    Producer :: producer()
+) -> ok.
+stop_producer(Producer) -> none.
+
 -spec append(Producer :: producer(), PartitionKey :: binary(), RawPayload :: binary()) ->
     ok.
 append(Producer, PartitionKey, RawPayload) ->