Remove sleep in import blocks (#6124)

* Add Delay and info logging

* Switch from Duration to Delay in enum declaration

* Remove sleep from import_blocks fn

* Set back constans and remove unnecessary code

* Fix hot loop

* Reset timer once poll is ready, not when it's pending

substrate/client/service/src/chain_ops.rs

@@ -39,7 +39,9 @@ use sp_core::storage::{StorageKey, well_known_keys, ChildInfo, Storage, StorageC
 use sc_client_api::{StorageProvider, BlockBackend, UsageProvider};
 
 use std::{io::{Read, Write, Seek}, pin::Pin, collections::HashMap};
-use std::{thread, time::{Duration, Instant}};
+use std::time::{Duration, Instant};
+use futures_timer::Delay;
+use std::task::Poll;
 use serde_json::{de::IoRead as JsonIoRead, Deserializer, StreamDeserializer};
 use std::convert::{TryFrom, TryInto};
 use sp_runtime::traits::{CheckedDiv, Saturating};
@@ -272,14 +274,14 @@ enum ImportState<R, B> where
 	/// The queue is full (contains at least MAX_PENDING_BLOCKS blocks) and we are waiting for it to catch up.
 	WaitingForImportQueueToCatchUp{
 		block_iter: BlockIter<R, B>,
-		delay: Duration,
+		delay: Delay,
 		block: SignedBlock<B>
 	},
 	// We have added all the blocks to the queue but they are still being processed.
 	WaitingForImportQueueToFinish{
 		num_expected_blocks: Option<u64>, 
 		read_block_count: u64,
-		delay: Duration,
+		delay: Delay,
 	},
 }
 
@@ -373,7 +375,7 @@ impl<
 							// The iterator is over: we now need to wait for the import queue to finish.
 							let num_expected_blocks = block_iter.num_expected_blocks();
 							let read_block_count = block_iter.read_block_count();
-							let delay = Duration::from_millis(DELAY_TIME);
+							let delay = Delay::new(Duration::from_millis(DELAY_TIME));
 							state = Some(ImportState::WaitingForImportQueueToFinish{num_expected_blocks, read_block_count, delay});
 						},
 						Some(block_result) => {
@@ -383,7 +385,7 @@ impl<
 									if read_block_count - link.imported_blocks >= MAX_PENDING_BLOCKS {
 										// The queue is full, so do not add this block and simply wait until
 										// the queue has made some progress.
-										let delay = Duration::from_millis(DELAY_TIME);
+										let delay = Delay::new(Duration::from_millis(DELAY_TIME));
 										state = Some(ImportState::WaitingForImportQueueToCatchUp{block_iter, delay, block});
 									} else {
 										// Queue is not full, we can keep on adding blocks to the queue.
@@ -392,18 +394,26 @@ impl<
 									}
 								}
 								Err(e) => {
-									return std::task::Poll::Ready(
+									return Poll::Ready(
 										Err(Error::Other(format!("Error reading block #{}: {}", read_block_count, e))))
 								}
 							}
 						}
 					}
 				},
-				ImportState::WaitingForImportQueueToCatchUp{block_iter, delay, block} => {
+				ImportState::WaitingForImportQueueToCatchUp{block_iter, mut delay, block} => {
 					let read_block_count = block_iter.read_block_count();
 					if read_block_count - link.imported_blocks >= MAX_PENDING_BLOCKS {
-						thread::sleep(delay);
 						// Queue is still full, so wait until there is room to insert our block.
+						match Pin::new(&mut delay).poll(cx) {
+							Poll::Pending => {
+								state = Some(ImportState::WaitingForImportQueueToCatchUp{block_iter, delay, block});
+								return Poll::Pending
+							},
+							Poll::Ready(_) => {
+								delay.reset(Duration::from_millis(DELAY_TIME));
+							},
+						}
 						state = Some(ImportState::WaitingForImportQueueToCatchUp{block_iter, delay, block});
 					} else {
 						// Queue is no longer full, so we can add our block to the queue.
@@ -412,7 +422,7 @@ impl<
 						state = Some(ImportState::Reading{block_iter});
 					}
 				},
-				ImportState::WaitingForImportQueueToFinish{num_expected_blocks, read_block_count, delay} => {
+				ImportState::WaitingForImportQueueToFinish{num_expected_blocks, read_block_count, mut delay} => {
 					// All the blocks have been added to the queue, which doesn't mean they 
 					// have all been properly imported.
 					if importing_is_done(num_expected_blocks, read_block_count, link.imported_blocks) {
@@ -421,10 +431,20 @@ impl<
 							"🎉 Imported {} blocks. Best: #{}",
 							read_block_count, client.chain_info().best_number
 						);
-						return std::task::Poll::Ready(Ok(()))
+						return Poll::Ready(Ok(()))
 					} else {
-						thread::sleep(delay);
 						// Importing is not done, we still have to wait for the queue to finish.
+						// Wait for the delay, because we know the queue is lagging behind.
+						match Pin::new(&mut delay).poll(cx) {
+							Poll::Pending => {
+								state = Some(ImportState::WaitingForImportQueueToFinish{num_expected_blocks, read_block_count, delay});
+								return Poll::Pending
+							},
+							Poll::Ready(_) => {
+								delay.reset(Duration::from_millis(DELAY_TIME));
+							},
+						}
+
 						state = Some(ImportState::WaitingForImportQueueToFinish{num_expected_blocks, read_block_count, delay});
 					}
 				}
@@ -436,7 +456,7 @@ impl<
 			speedometer.notify_user(best_number);
 
 			if link.has_error {
-				return std::task::Poll::Ready(Err(
+				return Poll::Ready(Err(
 					Error::Other(
 						format!("Stopping after #{} blocks because of an error", link.imported_blocks)
 					)
@@ -444,7 +464,7 @@ impl<
 			}
 
 			cx.waker().wake_by_ref();
-			std::task::Poll::Pending
+			Poll::Pending
 		});
 		Box::pin(import)
 	}
@@ -477,7 +497,7 @@ impl<
 			let client = &self.client;
 
 			if last < block {
-				return std::task::Poll::Ready(Err("Invalid block range specified".into()));
+				return Poll::Ready(Err("Invalid block range specified".into()));
 			}
 
 			if !wrote_header {
@@ -501,19 +521,19 @@ impl<
 					}
 			},
 				// Reached end of the chain.
-				None => return std::task::Poll::Ready(Ok(())),
+				None => return Poll::Ready(Ok(())),
 			}
 			if (block % 10000.into()).is_zero() {
 				info!("#{}", block);
 			}
 			if block == last {
-				return std::task::Poll::Ready(Ok(()));
+				return Poll::Ready(Ok(()));
 			}
 			block += One::one();
 
 			// Re-schedule the task in order to continue the operation.
 			cx.waker().wake_by_ref();
-			std::task::Poll::Pending
+			Poll::Pending
 		});
 
 		Box::pin(export)