*: Comment on calls

Author: leoyvens

chain/ethereum/src/network_indexer/network_indexer.rs

@@ -1174,7 +1174,8 @@ impl NetworkIndexer {
             start_block,
         });
 
-        // Launch state machine
+        // Launch state machine.
+        // Blocking due to store interactions. Won't be blocking after #905.
         graph::spawn_blocking(
             state_machine
                 .map_err(move |e| {

core/src/subgraph/instance_manager.rs

@@ -236,6 +236,7 @@ impl SubgraphInstanceManager {
         // Subgraph instance shutdown senders
         let instances: SharedInstanceKeepAliveMap = Default::default();
 
+        // Blocking due to store interactions. Won't be blocking after #905.
         graph::spawn_blocking(receiver.compat().try_for_each(move |event| {
             use self::SubgraphAssignmentProviderEvent::*;
 

core/src/subgraph/registrar.rs

@@ -111,7 +111,8 @@ where
 
         // Deploy named subgraphs found in store
         self.start_assigned_subgraphs().and_then(move |()| {
-            // Spawn a task to handle assignment events
+            // Spawn a task to handle assignment events.
+            // Blocking due to store interactions. Won't be blocking after #905.
             graph::spawn_blocking(
                 assignment_event_stream
                     .map_err(SubgraphAssignmentProviderError::Unknown)
@@ -255,6 +256,8 @@ where
                     let sender = sender.clone();
                     let provider = provider.clone();
                     let logger = logger.clone();
+                    
+                    // Blocking due to store interactions. Won't be blocking after #905.
                     graph::spawn_blocking(
                         start_subgraph(id, &*provider, logger)
                             .map(move |()| drop(sender))

graph/src/task_spawn.rs

@@ -14,16 +14,19 @@ fn abort_on_panic<T: Send + 'static>(
     })
 }
 
+/// Aborts on panic.
 pub fn spawn<T: Send + 'static>(f: impl Future03<Output = T> + Send + 'static) -> JoinHandle<T> {
     tokio::spawn(abort_on_panic(f))
 }
 
+/// Aborts on panic.
 pub fn spawn_blocking<T: Send + 'static>(
     f: impl Future03<Output = T> + Send + 'static,
 ) -> JoinHandle<T> {
     tokio::task::spawn_blocking(move || block_on(abort_on_panic(f)))
 }
 
+/// Panics result in an `Err` in `JoinHandle`.
 pub fn spawn_blocking_allow_panic<T: Send + 'static>(
     f: impl Future03<Output = T> + Send + 'static,
 ) -> JoinHandle<T> {

runtime/wasm/src/host_exports.rs

@@ -680,6 +680,7 @@ fn test_string_to_h160_with_0x() {
 fn block_on<I: Send + 'static, ER: Send + 'static>(
     future: impl Future<Item = I, Error = ER> + Send + 'static,
 ) -> Result<I, ER> {
+    // We don't know if the task is blocking or not, but use `blocking` to be cautious.
     graph::spawn_blocking_allow_panic(future.compat())
         .compat()
         .wait()

server/json-rpc/src/lib.rs

@@ -214,6 +214,7 @@ where
             mpsc::channel::<Box<dyn std::future::Future<Output = ()> + Send + Unpin>>(100);
         graph::spawn(task_receiver.for_each(|f| {
             async {
+                // Blocking due to store interactions. Won't be blocking after #905.
                 graph::spawn_blocking(f);
             }
         }));

server/websocket/src/server.rs

@@ -190,6 +190,8 @@ where
                                 ws_stream,
                                 graphql_runner.clone(),
                             );
+
+                            // Blocking due to store interactions. Won't be blocking after #905.
                             graph::spawn_blocking_allow_panic(service.into_future().compat());
                         }
                         Err(e) => {