backend: Add debug logs again

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>

subxt/src/backend/unstable/mod.rs

@@ -30,7 +30,7 @@ use crate::error::{Error, RpcError};
 use crate::Config;
 use async_trait::async_trait;
 use follow_stream_driver::{FollowStreamDriver, FollowStreamDriverHandle};
-use futures::{Stream, StreamExt};
+use futures::{SinkExt, Stream, StreamExt};
 use std::collections::HashMap;
 use std::sync::Arc;
 use std::task::Poll;
@@ -446,19 +446,7 @@ impl<T: Config + Send + Sync + 'static> Backend<T> for UnstableBackend<T> {
             Finalized,
         }
 
-        // First, subscribe to all new and finalized block refs.
+        let mut seen_blocks_sub = self.follow_handle.subscribe().events();
-        // - we subscribe to new refs so that when we see `BestChainBlockIncluded`, we
-        //   can try to return a block ref for the best block.
-        // - we subscribe to finalized refs so that when we see `Finalized`, we can
-        //   guarantee that when we return here, the finalized block we report has been
-        //   reported from chainHead_follow already.
-        let mut seen_blocks_sub = self.follow_handle.subscribe().events().filter_map(|ev| {
-            std::future::ready(match ev {
-                FollowEvent::NewBlock(ev) => Some(SeenBlock::New(ev.block_hash)),
-                FollowEvent::Finalized(ev) => Some(SeenBlock::Finalized(ev.finalized_block_hashes)),
-                _ => None,
-            })
-        });
 
         // Then, submit the transaction.
         let mut tx_progress = self
@@ -474,9 +462,23 @@ impl<T: Config + Send + Sync + 'static> Backend<T> for UnstableBackend<T> {
         // with chainHead_follow.
         let mut finalized_hash: Option<T::Hash> = None;
 
+        let mut mem_events = Vec::with_capacity(128);
+        let mut mem_tx_events = Vec::with_capacity(128);
+        let mut iter_num = 0;
+        let now = std::time::Instant::now();
+
         // Now we can attempt to associate tx events with pinned blocks.
         let tx_stream = futures::stream::poll_fn(move |cx| {
             loop {
+                iter_num += 1;
+
+                if now.elapsed().as_secs() > 120 {
+                    panic!(
+                        "iter={:#?}\nmem_events={:#?}\nmem_tx_events={:#?}",
+                        iter_num, mem_events, mem_tx_events
+                    );
+                }
+
                 // Bail early if no more tx events; we don't want to keep polling for pinned blocks.
                 if done {
                     return Poll::Ready(None);
@@ -484,24 +486,25 @@ impl<T: Config + Send + Sync + 'static> Backend<T> for UnstableBackend<T> {
 
                 // Make a note of new or finalized blocks that have come in since we started the TX.
                 if let Poll::Ready(Some(seen_block)) = seen_blocks_sub.poll_next_unpin(cx) {
+                    mem_events.push((now.elapsed(), seen_block.clone()));
+
                     match seen_block {
-                        SeenBlock::New(block_ref) => {
+                        FollowEvent::NewBlock(block_ref) => {
-                            // Optimization: once we have a `finalized_hash`, we only care about finalized
+                            seen_blocks.insert(
-                            // block refs now and can avoid bothering to save new blocks.
+                                block_ref.block_hash.hash(),
-                            if finalized_hash.is_none() {
+                                (SeenBlockMarker::New, block_ref.block_hash),
-                                seen_blocks
+                            );
-                                    .insert(block_ref.hash(), (SeenBlockMarker::New, block_ref));
-                            }
                         }
-                        SeenBlock::Finalized(block_refs) => {
+                        FollowEvent::Finalized(block_refs) => {
-                            for block_ref in block_refs {
+                            for block_ref in block_refs.finalized_block_hashes {
                                 seen_blocks.insert(
                                     block_ref.hash(),
                                     (SeenBlockMarker::Finalized, block_ref),
                                 );
                             }
                         }
-                    }
+                        _ => (),
+                    };
                     continue;
                 }
 
@@ -535,6 +538,8 @@ impl<T: Config + Send + Sync + 'static> Backend<T> for UnstableBackend<T> {
                     Poll::Ready(Some(Ok(ev))) => ev,
                 };
 
+                mem_tx_events.push((now.elapsed(), ev.clone()));
+
                 // When we get one, map it to the correct format (or for finalized ev, wait for the pinned block):
                 let ev = match ev {
                     rpc_methods::TransactionStatus::Finalized { block } => {