Port websockets, timer and notifier to stable futures (#1035)

* Fix lcli

* Port timer to stable futures

* Fix timer

* Port websocket_server to stable futures

* Port notifier to stable futures

* Add TODOS

* Port remote_beacon_node to stable futures

beacon_node/client/src/notifier.rs

@@ -2,13 +2,13 @@ use crate::metrics;
 use beacon_chain::{BeaconChain, BeaconChainTypes};
 use environment::RuntimeContext;
 use eth2_libp2p::NetworkGlobals;
-use futures::{Future, Stream};
+use futures::{FutureExt, StreamExt, TryFutureExt};
 use parking_lot::Mutex;
 use slog::{debug, error, info, warn};
 use slot_clock::SlotClock;
 use std::sync::Arc;
-use std::time::{Duration, Instant};
-use tokio::timer::Interval;
+use std::time::Duration;
+use tokio::time::{interval_at, Instant};
 use types::{EthSpec, Slot};
 
 /// Create a warning log whenever the peer count is at or below this value.
@@ -32,9 +32,7 @@ pub fn spawn_notifier<T: BeaconChainTypes>(
     network: Arc<NetworkGlobals<T::EthSpec>>,
     milliseconds_per_slot: u64,
 ) -> Result<tokio::sync::oneshot::Sender<()>, String> {
-    let log_1 = context.log.clone();
-    let log_2 = context.log.clone();
-    let log_3 = context.log.clone();
+    let log = context.log.clone();
 
     let slot_duration = Duration::from_millis(milliseconds_per_slot);
     let duration_to_next_slot = beacon_chain
@@ -50,82 +48,94 @@ pub fn spawn_notifier<T: BeaconChainTypes>(
 
     let speedo = Mutex::new(Speedo::default());
 
-    let interval_future = Interval::new(start_instant, interval_duration)
-        .map_err(
-            move |e| error!(log_1, "Slot notifier timer failed"; "error" => format!("{:?}", e)),
-        )
-        .for_each(move |_| {
-            let log = log_2.clone();
+    // Note: `interval_at` panics when interval_duration is 0
+    // TODO: `Return type of closure passed to `for_each` is restricted to `Future<Output = ()>`
+    // Hence, shifting the .then() error logs into the `for_each` closure.
+    // Can be solved with `TryStreamExt::try_for_each` if `Interval` implemented `TryStream`.
+    // Check if this can be refactored better.
+    let interval_future = interval_at(start_instant, interval_duration).for_each(|_| {
+        let connected_peer_count = network.connected_peers();
 
-            let connected_peer_count = network.connected_peers();
-
-            let head_info = beacon_chain.head_info()
-                .map_err(|e| error!(
-                    log,
-                    "Failed to get beacon chain head info";
-                    "error" => format!("{:?}", e)
-                ))?;
-
-            let head_slot = head_info.slot;
-            let head_epoch = head_slot.epoch(T::EthSpec::slots_per_epoch());
-            let current_slot = beacon_chain.slot().map_err(|e| {
+        let head_info = match beacon_chain.head_info() {
+            Ok(head) => head,
+            Err(e) => {
                 error!(
                     log,
-                    "Unable to read current slot";
+                    "Notifier failed to notify, Failed to get beacon chain head info";
                     "error" => format!("{:?}", e)
-                )
-            })?;
-            let current_epoch = current_slot.epoch(T::EthSpec::slots_per_epoch());
-            let finalized_epoch = head_info.finalized_checkpoint.epoch;
-            let finalized_root = head_info.finalized_checkpoint.root;
-            let head_root = head_info.block_root;
-
-            let mut speedo = speedo.lock();
-            speedo.observe(head_slot, Instant::now());
-
-            metrics::set_gauge(&metrics::SYNC_SLOTS_PER_SECOND, speedo.slots_per_second().unwrap_or_else(|| 0_f64) as i64);
-
-            // The next two lines take advantage of saturating subtraction on `Slot`.
-            let head_distance = current_slot - head_slot;
-
-            if connected_peer_count <= WARN_PEER_COUNT {
-                warn!(log, "Low peer count"; "peer_count" => peer_count_pretty(connected_peer_count));
+                );
+                return futures::future::ready(());
             }
+        };
 
-            debug!(
-                log,
-                "Slot timer";
-                "peers" => peer_count_pretty(connected_peer_count),
-                "finalized_root" => format!("{}", finalized_root),
-                "finalized_epoch" => finalized_epoch,
-                "head_block" => format!("{}", head_root),
-                "head_slot" => head_slot,
-                "current_slot" => current_slot,
+        let head_slot = head_info.slot;
+        let head_epoch = head_slot.epoch(T::EthSpec::slots_per_epoch());
+        let current_slot = match beacon_chain.slot() {
+            Ok(slot) => slot,
+            Err(e) => {
+                error!(
+                    log,
+                    "Notify failed to notify, Unable to read current slot";
+                    "error" => format!("{:?}", e)
+                );
+                return futures::future::ready(());
+            }
+        };
+
+        let current_epoch = current_slot.epoch(T::EthSpec::slots_per_epoch());
+        let finalized_epoch = head_info.finalized_checkpoint.epoch;
+        let finalized_root = head_info.finalized_checkpoint.root;
+        let head_root = head_info.block_root;
+
+        let mut speedo = speedo.lock();
+        speedo.observe(head_slot, Instant::now());
+
+        metrics::set_gauge(
+            &metrics::SYNC_SLOTS_PER_SECOND,
+            speedo.slots_per_second().unwrap_or_else(|| 0_f64) as i64,
+        );
+
+        // The next two lines take advantage of saturating subtraction on `Slot`.
+        let head_distance = current_slot - head_slot;
+
+        if connected_peer_count <= WARN_PEER_COUNT {
+            warn!(log, "Low peer count"; "peer_count" => peer_count_pretty(connected_peer_count));
+        }
+
+        debug!(
+            log,
+            "Slot timer";
+            "peers" => peer_count_pretty(connected_peer_count),
+            "finalized_root" => format!("{}", finalized_root),
+            "finalized_epoch" => finalized_epoch,
+            "head_block" => format!("{}", head_root),
+            "head_slot" => head_slot,
+            "current_slot" => current_slot,
+        );
+
+        if head_epoch + 1 < current_epoch {
+            let distance = format!(
+                "{} slots ({})",
+                head_distance.as_u64(),
+                slot_distance_pretty(head_distance, slot_duration)
             );
 
-            if head_epoch + 1 < current_epoch {
-                let distance = format!(
-                    "{} slots ({})",
-                    head_distance.as_u64(),
-                    slot_distance_pretty(head_distance, slot_duration)
-                );
+            info!(
+                log,
+                "Syncing";
+                "peers" => peer_count_pretty(connected_peer_count),
+                "distance" => distance,
+                "speed" => sync_speed_pretty(speedo.slots_per_second()),
+                "est_time" => estimated_time_pretty(speedo.estimated_time_till_slot(current_slot)),
+            );
 
-                info!(
-                    log,
-                    "Syncing";
-                    "peers" => peer_count_pretty(connected_peer_count),
-                    "distance" => distance,
-                    "speed" => sync_speed_pretty(speedo.slots_per_second()),
-                    "est_time" => estimated_time_pretty(speedo.estimated_time_till_slot(current_slot)),
-                );
+            return futures::future::ready(());
+        };
 
-                return Ok(());
-            };
-
-            macro_rules! not_quite_synced_log {
+        macro_rules! not_quite_synced_log {
                 ($message: expr) => {
                     info!(
-                        log_2,
+                        log,
                         $message;
                         "peers" => peer_count_pretty(connected_peer_count),
                         "finalized_root" => format!("{}", finalized_root),
@@ -136,41 +146,31 @@ pub fn spawn_notifier<T: BeaconChainTypes>(
                 }
             }
 
-            if head_epoch + 1 == current_epoch {
-                not_quite_synced_log!("Synced to previous epoch")
-            } else if head_slot != current_slot {
-                not_quite_synced_log!("Synced to current epoch")
-            } else {
-                info!(
-                    log_2,
-                    "Synced";
-                    "peers" => peer_count_pretty(connected_peer_count),
-                    "finalized_root" => format!("{}", finalized_root),
-                    "finalized_epoch" => finalized_epoch,
-                    "epoch" => current_epoch,
-                    "slot" => current_slot,
-                );
-            };
+        if head_epoch + 1 == current_epoch {
+            not_quite_synced_log!("Synced to previous epoch")
+        } else if head_slot != current_slot {
+            not_quite_synced_log!("Synced to current epoch")
+        } else {
+            info!(
+                log,
+                "Synced";
+                "peers" => peer_count_pretty(connected_peer_count),
+                "finalized_root" => format!("{}", finalized_root),
+                "finalized_epoch" => finalized_epoch,
+                "epoch" => current_epoch,
+                "slot" => current_slot,
+            );
+        };
 
-            Ok(())
-        })
-        .then(move |result| {
-            match result {
-                Ok(()) => Ok(()),
-                Err(e) => {
-                    error!(
-                    log_3,
-                    "Notifier failed to notify";
-                    "error" => format!("{:?}", e)
-                );
-                Ok(())
-            } } });
+        futures::future::ready(())
+    });
 
     let (exit_signal, exit) = tokio::sync::oneshot::channel();
 
-    context
-        .executor
-        .spawn(interval_future.select(exit).map(|_| ()).map_err(|_| ()));
+    let future = futures::future::select(interval_future, exit.map_err(|_| ()).map(|_| ()));
+
+    // TODO: check if the runtime handle should spawn this future.
+    tokio::task::spawn(future);
 
     Ok(exit_signal)
 }

beacon_node/timer/Cargo.toml

@@ -8,7 +8,7 @@ edition = "2018"
 beacon_chain =  { path = "../beacon_chain" }
 types = { path = "../../eth2/types" }
 slot_clock = { path = "../../eth2/utils/slot_clock" }
-tokio = "0.1.22"
+tokio = { version = "0.2", features = ["full"] }
 slog = "2.5.2"
 parking_lot = "0.10.0"
-futures = "0.1.29"
+futures = "0.3"

beacon_node/timer/src/lib.rs

@@ -3,20 +3,22 @@
 //! This service allows task execution on the beacon node for various functionality.
 
 use beacon_chain::{BeaconChain, BeaconChainTypes};
+use futures::stream::StreamExt;
 use futures::{future, prelude::*};
-use slog::error;
 use slot_clock::SlotClock;
 use std::sync::Arc;
-use std::time::{Duration, Instant};
-use tokio::runtime::TaskExecutor;
-use tokio::timer::Interval;
+use std::time::Duration;
+use tokio::runtime::Handle;
+use tokio::time::{interval_at, Instant};
 
 /// Spawns a timer service which periodically executes tasks for the beacon chain
+/// TODO: We might not need a `Handle` to the runtime since this function should be
+/// called from the context of a runtime and we can simply spawn using task::spawn.
+/// Check for issues without the Handle.
 pub fn spawn<T: BeaconChainTypes>(
-    executor: &TaskExecutor,
+    handle: &Handle,
     beacon_chain: Arc<BeaconChain<T>>,
     milliseconds_per_slot: u64,
-    log: slog::Logger,
 ) -> Result<tokio::sync::oneshot::Sender<()>, &'static str> {
     let (exit_signal, exit) = tokio::sync::oneshot::channel();
 
@@ -26,25 +28,15 @@ pub fn spawn<T: BeaconChainTypes>(
             .duration_to_next_slot()
             .ok_or_else(|| "slot_notifier unable to determine time to next slot")?;
 
-    let timer_future = Interval::new(start_instant, Duration::from_millis(milliseconds_per_slot))
-        .map_err(move |e| {
-            error!(
-                log,
-                "Beacon chain timer failed";
-                "error" => format!("{:?}", e)
-            )
-        })
+    // Warning: `interval_at` panics if `milliseconds_per_slot` = 0.
+    let timer_future = interval_at(start_instant, Duration::from_millis(milliseconds_per_slot))
         .for_each(move |_| {
             beacon_chain.per_slot_task();
-            future::ok(())
+            future::ready(())
         });
 
-    executor.spawn(
-        exit.map_err(|_| ())
-            .select(timer_future)
-            .map(|_| ())
-            .map_err(|_| ()),
-    );
+    let future = futures::future::select(timer_future, exit.map_err(|_| ()).map(|_| ()));
+    handle.spawn(future);
 
     Ok(exit_signal)
 }

beacon_node/websocket_server/Cargo.toml

@@ -7,11 +7,11 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-futures = "0.1.29"
+futures = "0.3"
 serde = "1.0.102"
 serde_derive = "1.0.102"
 serde_json = "1.0.41"
 slog = "2.5.2"
-tokio = "0.1.22"
+tokio = { version = "0.2", features = ["full"] }
 types = { path = "../../eth2/types" }
 ws = "0.9.1"

beacon_node/websocket_server/src/lib.rs

@@ -1,9 +1,8 @@
-use futures::Future;
+use futures::future::TryFutureExt;
 use slog::{debug, error, info, warn, Logger};
 use std::marker::PhantomData;
 use std::net::SocketAddr;
-use std::thread;
-use tokio::runtime::TaskExecutor;
+use tokio::runtime::Handle;
 use types::EthSpec;
 use ws::{Sender, WebSocket};
 
@@ -38,7 +37,7 @@ impl<T: EthSpec> WebSocketSender<T> {
 
 pub fn start_server<T: EthSpec>(
     config: &Config,
-    executor: &TaskExecutor,
+    handle: &Handle,
     log: &Logger,
 ) -> Result<
     (
@@ -87,19 +86,22 @@ pub fn start_server<T: EthSpec>(
                 } else {
                     info!(log_inner, "Websocket server shutdown");
                 }
-                Ok(())
+                futures::future::ok(())
             })
             .map_err(|_| ());
 
-        // Place a future on the executor that will shutdown the websocket server when the
+        // Place a future on the handle that will shutdown the websocket server when the
         // application exits.
-        executor.spawn(exit_future);
+        // TODO: check if we should spawn using a `Handle` or using `task::spawn`
+        handle.spawn(exit_future);
 
         exit_channel
     };
 
     let log_inner = log.clone();
-    let _handle = thread::spawn(move || match server.run() {
+    // TODO: using tokio `spawn_blocking` instead of `thread::spawn`
+    // Check which is more apt.
+    let _handle = tokio::task::spawn_blocking(move || match server.run() {
         Ok(_) => {
             debug!(
                 log_inner,

eth2/utils/remote_beacon_node/Cargo.toml

@@ -7,10 +7,10 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-reqwest = "0.9"
+reqwest = { version = "0.10", features = ["json"] }
 url = "1.2"
 serde = "1.0"
-futures = "0.1.25"
+futures = "0.3.4"
 types = { path = "../../../eth2/types" }
 rest_types = { path = "../rest_types" }
 hex = "0.3"

eth2/utils/remote_beacon_node/src/lib.rs

@@ -4,11 +4,7 @@
 //! Presently, this is only used for testing but it _could_ become a user-facing library.
 
 use eth2_config::Eth2Config;
-use futures::{future, Future, IntoFuture};
-use reqwest::{
-    r#async::{Client, ClientBuilder, Response},
-    StatusCode,
-};
+use reqwest::{Client, ClientBuilder, Response, StatusCode};
 use serde::{de::DeserializeOwned, Deserialize, Serialize};
 use ssz::Encode;
 use std::marker::PhantomData;
@@ -119,33 +115,33 @@ impl<E: EthSpec> HttpClient<E> {
         self.url.join(path).map_err(|e| e.into())
     }
 
-    pub fn json_post<T: Serialize>(
-        &self,
-        url: Url,
-        body: T,
-    ) -> impl Future<Item = Response, Error = Error> {
+    pub async fn json_post<T: Serialize>(&self, url: Url, body: T) -> Result<Response, Error> {
         self.client
             .post(&url.to_string())
             .json(&body)
             .send()
+            .await
             .map_err(Error::from)
     }
 
-    pub fn json_get<T: DeserializeOwned>(
+    pub async fn json_get<T: DeserializeOwned>(
         &self,
         mut url: Url,
         query_pairs: Vec<(String, String)>,
-    ) -> impl Future<Item = T, Error = Error> {
+    ) -> Result<T, Error> {
         query_pairs.into_iter().for_each(|(key, param)| {
             url.query_pairs_mut().append_pair(&key, &param);
         });
 
-        self.client
+        let response = self
+            .client
             .get(&url.to_string())
             .send()
-            .map_err(Error::from)
-            .and_then(|response| error_for_status(response).map_err(Error::from))
-            .and_then(|mut success| success.json::<T>().map_err(Error::from))
+            .await
+            .map_err(Error::from)?;
+
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json::<T>().await.map_err(Error::from)
     }
 }
 
@@ -153,18 +149,17 @@ impl<E: EthSpec> HttpClient<E> {
 ///
 /// Distinct from `Response::error_for_status` because it includes the body of the response as
 /// text. This ensures the error message from the server is not discarded.
-fn error_for_status(
-    mut response: Response,
-) -> Box<dyn Future<Item = Response, Error = Error> + Send> {
+async fn error_for_status(response: Response) -> Result<Response, Error> {
     let status = response.status();
 
     if status.is_success() {
-        Box::new(future::ok(response))
+        return Ok(response);
     } else {
-        Box::new(response.text().then(move |text_result| match text_result {
+        let text_result = response.text().await;
+        match text_result {
             Err(e) => Err(Error::ReqwestError(e)),
             Ok(body) => Err(Error::DidNotSucceed { status, body }),
-        }))
+        }
     }
 }
 
@@ -199,94 +194,86 @@ impl<E: EthSpec> Validator<E> {
     }
 
     /// Produces an unsigned attestation.
-    pub fn produce_attestation(
+    pub async fn produce_attestation(
         &self,
         slot: Slot,
         committee_index: CommitteeIndex,
-    ) -> impl Future<Item = Attestation<E>, Error = Error> {
+    ) -> Result<Attestation<E>, Error> {
         let query_params = vec![
             ("slot".into(), format!("{}", slot)),
             ("committee_index".into(), format!("{}", committee_index)),
         ];
 
         let client = self.0.clone();
-        self.url("attestation")
-            .into_future()
-            .and_then(move |url| client.json_get(url, query_params))
+        let url = self.url("attestation")?;
+        client.json_get(url, query_params).await
     }
 
     /// Produces an aggregate attestation.
-    pub fn produce_aggregate_attestation(
+    pub async fn produce_aggregate_attestation(
         &self,
         attestation_data: &AttestationData,
-    ) -> impl Future<Item = Attestation<E>, Error = Error> {
+    ) -> Result<Attestation<E>, Error> {
         let query_params = vec![(
             "attestation_data".into(),
             as_ssz_hex_string(attestation_data),
         )];
 
         let client = self.0.clone();
-        self.url("aggregate_attestation")
-            .into_future()
-            .and_then(move |url| client.json_get(url, query_params))
+        let url = self.url("aggregate_attestation")?;
+        client.json_get(url, query_params).await
     }
 
     /// Posts a list of attestations to the beacon node, expecting it to verify it and publish it to the network.
-    pub fn publish_attestations(
+    pub async fn publish_attestations(
         &self,
         attestation: Vec<Attestation<E>>,
-    ) -> impl Future<Item = PublishStatus, Error = Error> {
+    ) -> Result<PublishStatus, Error> {
         let client = self.0.clone();
-        self.url("attestations")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, attestation))
-            .and_then(|mut response| {
-                response
-                    .text()
-                    .map(|text| (response, text))
-                    .map_err(Error::from)
-            })
-            .and_then(|(response, text)| match response.status() {
-                StatusCode::OK => Ok(PublishStatus::Valid),
-                StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(text)),
-                _ => response
-                    .error_for_status()
-                    .map_err(Error::from)
-                    .map(|_| PublishStatus::Unknown),
-            })
+        let url = self.url("attestations")?;
+        let response = client.json_post::<_>(url, attestation).await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
     }
 
     /// Posts a list of signed aggregates and proofs to the beacon node, expecting it to verify it and publish it to the network.
-    pub fn publish_aggregate_and_proof(
+    pub async fn publish_aggregate_and_proof(
         &self,
         signed_aggregate_and_proofs: Vec<SignedAggregateAndProof<E>>,
-    ) -> impl Future<Item = PublishStatus, Error = Error> {
+    ) -> Result<PublishStatus, Error> {
         let client = self.0.clone();
-        self.url("aggregate_and_proofs")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, signed_aggregate_and_proofs))
-            .and_then(|mut response| {
-                response
-                    .text()
-                    .map(|text| (response, text))
-                    .map_err(Error::from)
-            })
-            .and_then(|(response, text)| match response.status() {
-                StatusCode::OK => Ok(PublishStatus::Valid),
-                StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(text)),
-                _ => response
-                    .error_for_status()
-                    .map_err(Error::from)
-                    .map(|_| PublishStatus::Unknown),
-            })
+        let url = self.url("aggregate_and_proofs")?;
+        let response = client
+            .json_post::<_>(url, signed_aggregate_and_proofs)
+            .await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
     }
 
     /// Returns the duties required of the given validator pubkeys in the given epoch.
-    pub fn get_duties(
+    pub async fn get_duties(
         &self,
         epoch: Epoch,
         validator_pubkeys: &[PublicKey],
-    ) -> impl Future<Item = Vec<ValidatorDutyBytes>, Error = Error> {
+    ) -> Result<Vec<ValidatorDutyBytes>, Error> {
         let client = self.0.clone();
 
         let bulk_request = ValidatorDutiesRequest {
@@ -297,79 +284,68 @@ impl<E: EthSpec> Validator<E> {
                 .collect(),
         };
 
-        self.url("duties")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, bulk_request))
-            .and_then(|response| error_for_status(response).map_err(Error::from))
-            .and_then(|mut success| success.json().map_err(Error::from))
+        let url = self.url("duties")?;
+        let response = client.json_post::<_>(url, bulk_request).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
     }
 
     /// Posts a block to the beacon node, expecting it to verify it and publish it to the network.
-    pub fn publish_block(
-        &self,
-        block: SignedBeaconBlock<E>,
-    ) -> impl Future<Item = PublishStatus, Error = Error> {
+    pub async fn publish_block(&self, block: SignedBeaconBlock<E>) -> Result<PublishStatus, Error> {
         let client = self.0.clone();
-        self.url("block")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, block))
-            .and_then(|mut response| {
-                response
-                    .text()
-                    .map(|text| (response, text))
-                    .map_err(Error::from)
-            })
-            .and_then(|(response, text)| match response.status() {
-                StatusCode::OK => Ok(PublishStatus::Valid),
-                StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(text)),
-                _ => response
-                    .error_for_status()
-                    .map_err(Error::from)
-                    .map(|_| PublishStatus::Unknown),
-            })
+        let url = self.url("block")?;
+        let response = client.json_post::<_>(url, block).await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
     }
 
     /// Requests a new (unsigned) block from the beacon node.
-    pub fn produce_block(
+    pub async fn produce_block(
         &self,
         slot: Slot,
         randao_reveal: Signature,
-    ) -> impl Future<Item = BeaconBlock<E>, Error = Error> {
+    ) -> Result<BeaconBlock<E>, Error> {
         let client = self.0.clone();
-        self.url("block").into_future().and_then(move |url| {
-            client.json_get::<BeaconBlock<E>>(
+        let url = self.url("block")?;
+        client
+            .json_get::<BeaconBlock<E>>(
                 url,
                 vec![
                     ("slot".into(), format!("{}", slot.as_u64())),
                     ("randao_reveal".into(), as_ssz_hex_string(&randao_reveal)),
                 ],
             )
-        })
+            .await
     }
 
     /// Subscribes a list of validators to particular slots for attestation production/publication.
-    pub fn subscribe(
+    pub async fn subscribe(
         &self,
         subscriptions: Vec<ValidatorSubscription>,
-    ) -> impl Future<Item = PublishStatus, Error = Error> {
+    ) -> Result<PublishStatus, Error> {
         let client = self.0.clone();
-        self.url("subscribe")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, subscriptions))
-            .and_then(|mut response| {
-                response
-                    .text()
-                    .map(|text| (response, text))
-                    .map_err(Error::from)
-            })
-            .and_then(|(response, text)| match response.status() {
-                StatusCode::OK => Ok(PublishStatus::Valid),
-                StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(text)),
-                _ => response
-                    .error_for_status()
-                    .map_err(Error::from)
-                    .map(|_| PublishStatus::Unknown),
-            })
+        let url = self.url("subscribe")?;
+        let response = client.json_post::<_>(url, subscriptions).await?;
+
+        match response.status() {
+            StatusCode::OK => Ok(PublishStatus::Valid),
+            StatusCode::ACCEPTED => Ok(PublishStatus::Invalid(
+                response.text().await.map_err(Error::from)?,
+            )),
+            _ => response
+                .error_for_status()
+                .map_err(Error::from)
+                .map(|_| PublishStatus::Unknown),
+        }
     }
 }
 
@@ -386,120 +362,116 @@ impl<E: EthSpec> Beacon<E> {
     }
 
     /// Returns the genesis time.
-    pub fn get_genesis_time(&self) -> impl Future<Item = u64, Error = Error> {
+    pub async fn get_genesis_time(&self) -> Result<u64, Error> {
         let client = self.0.clone();
-        self.url("genesis_time")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("genesis_time")?;
+        client.json_get(url, vec![]).await
     }
 
     /// Returns the genesis validators root.
-    pub fn get_genesis_validators_root(&self) -> impl Future<Item = Hash256, Error = Error> {
+    pub async fn get_genesis_validators_root(&self) -> Result<Hash256, Error> {
         let client = self.0.clone();
-        self.url("genesis_validators_root")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("genesis_validators_root")?;
+        client.json_get(url, vec![]).await
     }
 
     /// Returns the fork at the head of the beacon chain.
-    pub fn get_fork(&self) -> impl Future<Item = Fork, Error = Error> {
+    pub async fn get_fork(&self) -> Result<Fork, Error> {
         let client = self.0.clone();
-        self.url("fork")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("fork")?;
+        client.json_get(url, vec![]).await
     }
 
     /// Returns info about the head of the canonical beacon chain.
-    pub fn get_head(&self) -> impl Future<Item = CanonicalHeadResponse, Error = Error> {
+    pub async fn get_head(&self) -> Result<CanonicalHeadResponse, Error> {
         let client = self.0.clone();
-        self.url("head")
-            .into_future()
-            .and_then(move |url| client.json_get::<CanonicalHeadResponse>(url, vec![]))
+        let url = self.url("head")?;
+        client.json_get::<CanonicalHeadResponse>(url, vec![]).await
     }
 
     /// Returns the set of known beacon chain head blocks. One of these will be the canonical head.
-    pub fn get_heads(&self) -> impl Future<Item = Vec<HeadBeaconBlock>, Error = Error> {
+    pub async fn get_heads(&self) -> Result<Vec<HeadBeaconBlock>, Error> {
         let client = self.0.clone();
-        self.url("heads")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("heads")?;
+        client.json_get(url, vec![]).await
     }
 
     /// Returns the block and block root at the given slot.
-    pub fn get_block_by_slot(
+    pub async fn get_block_by_slot(
         &self,
         slot: Slot,
-    ) -> impl Future<Item = (SignedBeaconBlock<E>, Hash256), Error = Error> {
+    ) -> Result<(SignedBeaconBlock<E>, Hash256), Error> {
         self.get_block("slot".to_string(), format!("{}", slot.as_u64()))
+            .await
     }
 
     /// Returns the block and block root at the given root.
-    pub fn get_block_by_root(
+    pub async fn get_block_by_root(
         &self,
         root: Hash256,
-    ) -> impl Future<Item = (SignedBeaconBlock<E>, Hash256), Error = Error> {
+    ) -> Result<(SignedBeaconBlock<E>, Hash256), Error> {
         self.get_block("root".to_string(), root_as_string(root))
+            .await
     }
 
     /// Returns the block and block root at the given slot.
-    fn get_block(
+    async fn get_block(
         &self,
         query_key: String,
         query_param: String,
-    ) -> impl Future<Item = (SignedBeaconBlock<E>, Hash256), Error = Error> {
+    ) -> Result<(SignedBeaconBlock<E>, Hash256), Error> {
         let client = self.0.clone();
-        self.url("block")
-            .into_future()
-            .and_then(move |url| {
-                client.json_get::<BlockResponse<E>>(url, vec![(query_key, query_param)])
-            })
+        let url = self.url("block")?;
+        client
+            .json_get::<BlockResponse<E>>(url, vec![(query_key, query_param)])
+            .await
             .map(|response| (response.beacon_block, response.root))
     }
 
     /// Returns the state and state root at the given slot.
-    pub fn get_state_by_slot(
-        &self,
-        slot: Slot,
-    ) -> impl Future<Item = (BeaconState<E>, Hash256), Error = Error> {
+    pub async fn get_state_by_slot(&self, slot: Slot) -> Result<(BeaconState<E>, Hash256), Error> {
         self.get_state("slot".to_string(), format!("{}", slot.as_u64()))
+            .await
     }
 
     /// Returns the state and state root at the given root.
-    pub fn get_state_by_root(
+    pub async fn get_state_by_root(
         &self,
         root: Hash256,
-    ) -> impl Future<Item = (BeaconState<E>, Hash256), Error = Error> {
+    ) -> Result<(BeaconState<E>, Hash256), Error> {
         self.get_state("root".to_string(), root_as_string(root))
+            .await
     }
 
     /// Returns the root of the state at the given slot.
-    pub fn get_state_root(&self, slot: Slot) -> impl Future<Item = Hash256, Error = Error> {
+    pub async fn get_state_root(&self, slot: Slot) -> Result<Hash256, Error> {
         let client = self.0.clone();
-        self.url("state_root").into_future().and_then(move |url| {
-            client.json_get(url, vec![("slot".into(), format!("{}", slot.as_u64()))])
-        })
+        let url = self.url("state_root")?;
+        client
+            .json_get(url, vec![("slot".into(), format!("{}", slot.as_u64()))])
+            .await
     }
 
     /// Returns the root of the block at the given slot.
-    pub fn get_block_root(&self, slot: Slot) -> impl Future<Item = Hash256, Error = Error> {
+    pub async fn get_block_root(&self, slot: Slot) -> Result<Hash256, Error> {
         let client = self.0.clone();
-        self.url("block_root").into_future().and_then(move |url| {
-            client.json_get(url, vec![("slot".into(), format!("{}", slot.as_u64()))])
-        })
+        let url = self.url("block_root")?;
+        client
+            .json_get(url, vec![("slot".into(), format!("{}", slot.as_u64()))])
+            .await
     }
 
     /// Returns the state and state root at the given slot.
-    fn get_state(
+    async fn get_state(
         &self,
         query_key: String,
         query_param: String,
-    ) -> impl Future<Item = (BeaconState<E>, Hash256), Error = Error> {
+    ) -> Result<(BeaconState<E>, Hash256), Error> {
         let client = self.0.clone();
-        self.url("state")
-            .into_future()
-            .and_then(move |url| {
-                client.json_get::<StateResponse<E>>(url, vec![(query_key, query_param)])
-            })
+        let url = self.url("state")?;
+        client
+            .json_get::<StateResponse<E>>(url, vec![(query_key, query_param)])
+            .await
             .map(|response| (response.beacon_state, response.root))
     }
 
@@ -507,11 +479,11 @@ impl<E: EthSpec> Beacon<E> {
     ///
     /// If `state_root` is `Some`, the query will use the given state instead of the default
     /// canonical head state.
-    pub fn get_validators(
+    pub async fn get_validators(
         &self,
         validator_pubkeys: Vec<PublicKey>,
         state_root: Option<Hash256>,
-    ) -> impl Future<Item = Vec<ValidatorResponse>, Error = Error> {
+    ) -> Result<Vec<ValidatorResponse>, Error> {
         let client = self.0.clone();
 
         let bulk_request = ValidatorRequest {
@@ -522,21 +494,20 @@ impl<E: EthSpec> Beacon<E> {
                 .collect(),
         };
 
-        self.url("validators")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, bulk_request))
-            .and_then(|response| error_for_status(response).map_err(Error::from))
-            .and_then(|mut success| success.json().map_err(Error::from))
+        let url = self.url("validators")?;
+        let response = client.json_post::<_>(url, bulk_request).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
     }
 
     /// Returns all validators.
     ///
     /// If `state_root` is `Some`, the query will use the given state instead of the default
     /// canonical head state.
-    pub fn get_all_validators(
+    pub async fn get_all_validators(
         &self,
         state_root: Option<Hash256>,
-    ) -> impl Future<Item = Vec<ValidatorResponse>, Error = Error> {
+    ) -> Result<Vec<ValidatorResponse>, Error> {
         let client = self.0.clone();
 
         let query_params = if let Some(state_root) = state_root {
@@ -545,19 +516,18 @@ impl<E: EthSpec> Beacon<E> {
             vec![]
         };
 
-        self.url("validators/all")
-            .into_future()
-            .and_then(move |url| client.json_get(url, query_params))
+        let url = self.url("validators/all")?;
+        client.json_get(url, query_params).await
     }
 
     /// Returns the active validators.
     ///
     /// If `state_root` is `Some`, the query will use the given state instead of the default
     /// canonical head state.
-    pub fn get_active_validators(
+    pub async fn get_active_validators(
         &self,
         state_root: Option<Hash256>,
-    ) -> impl Future<Item = Vec<ValidatorResponse>, Error = Error> {
+    ) -> Result<Vec<ValidatorResponse>, Error> {
         let client = self.0.clone();
 
         let query_params = if let Some(state_root) = state_root {
@@ -566,53 +536,42 @@ impl<E: EthSpec> Beacon<E> {
             vec![]
         };
 
-        self.url("validators/active")
-            .into_future()
-            .and_then(move |url| client.json_get(url, query_params))
+        let url = self.url("validators/active")?;
+        client.json_get(url, query_params).await
     }
 
     /// Returns committees at the given epoch.
-    pub fn get_committees(
-        &self,
-        epoch: Epoch,
-    ) -> impl Future<Item = Vec<Committee>, Error = Error> {
+    pub async fn get_committees(&self, epoch: Epoch) -> Result<Vec<Committee>, Error> {
         let client = self.0.clone();
 
-        self.url("committees").into_future().and_then(move |url| {
-            client.json_get(url, vec![("epoch".into(), format!("{}", epoch.as_u64()))])
-        })
+        let url = self.url("committees")?;
+        client
+            .json_get(url, vec![("epoch".into(), format!("{}", epoch.as_u64()))])
+            .await
     }
 
-    pub fn proposer_slashing(
+    pub async fn proposer_slashing(
         &self,
         proposer_slashing: ProposerSlashing,
-    ) -> impl Future<Item = bool, Error = Error> {
+    ) -> Result<bool, Error> {
         let client = self.0.clone();
 
-        self.url("proposer_slashing")
-            .into_future()
-            .and_then(move |url| {
-                client
-                    .json_post::<_>(url, proposer_slashing)
-                    .and_then(|response| error_for_status(response).map_err(Error::from))
-                    .and_then(|mut success| success.json().map_err(Error::from))
-            })
+        let url = self.url("proposer_slashing")?;
+        let response = client.json_post::<_>(url, proposer_slashing).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
     }
 
-    pub fn attester_slashing(
+    pub async fn attester_slashing(
         &self,
         attester_slashing: AttesterSlashing<E>,
-    ) -> impl Future<Item = bool, Error = Error> {
+    ) -> Result<bool, Error> {
         let client = self.0.clone();
 
-        self.url("attester_slashing")
-            .into_future()
-            .and_then(move |url| {
-                client
-                    .json_post::<_>(url, attester_slashing)
-                    .and_then(|response| error_for_status(response).map_err(Error::from))
-                    .and_then(|mut success| success.json().map_err(Error::from))
-            })
+        let url = self.url("attester_slashing")?;
+        let response = client.json_post::<_>(url, attester_slashing).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
     }
 }
 
@@ -628,11 +587,10 @@ impl<E: EthSpec> Spec<E> {
             .map_err(Into::into)
     }
 
-    pub fn get_eth2_config(&self) -> impl Future<Item = Eth2Config, Error = Error> {
+    pub async fn get_eth2_config(&self) -> Result<Eth2Config, Error> {
         let client = self.0.clone();
-        self.url("eth2_config")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("eth2_config")?;
+        client.json_get(url, vec![]).await
     }
 }
 
@@ -648,11 +606,10 @@ impl<E: EthSpec> Node<E> {
             .map_err(Into::into)
     }
 
-    pub fn get_version(&self) -> impl Future<Item = String, Error = Error> {
+    pub async fn get_version(&self) -> Result<String, Error> {
         let client = self.0.clone();
-        self.url("version")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("version")?;
+        client.json_get(url, vec![]).await
     }
 }
 
@@ -669,21 +626,17 @@ impl<E: EthSpec> Advanced<E> {
     }
 
     /// Gets the core `ProtoArray` struct from the node.
-    pub fn get_fork_choice(&self) -> impl Future<Item = ProtoArray, Error = Error> {
+    pub async fn get_fork_choice(&self) -> Result<ProtoArray, Error> {
         let client = self.0.clone();
-        self.url("fork_choice")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("fork_choice")?;
+        client.json_get(url, vec![]).await
     }
 
     /// Gets the core `PersistedOperationPool` struct from the node.
-    pub fn get_operation_pool(
-        &self,
-    ) -> impl Future<Item = PersistedOperationPool<E>, Error = Error> {
+    pub async fn get_operation_pool(&self) -> Result<PersistedOperationPool<E>, Error> {
         let client = self.0.clone();
-        self.url("operation_pool")
-            .into_future()
-            .and_then(move |url| client.json_get(url, vec![]))
+        let url = self.url("operation_pool")?;
+        client.json_get(url, vec![]).await
     }
 }
 
@@ -700,31 +653,26 @@ impl<E: EthSpec> Consensus<E> {
     }
 
     /// Gets a `IndividualVote` for each of the given `pubkeys`.
-    pub fn get_individual_votes(
+    pub async fn get_individual_votes(
         &self,
         epoch: Epoch,
         pubkeys: Vec<PublicKeyBytes>,
-    ) -> impl Future<Item = IndividualVotesResponse, Error = Error> {
+    ) -> Result<IndividualVotesResponse, Error> {
         let client = self.0.clone();
         let req_body = IndividualVotesRequest { epoch, pubkeys };
 
-        self.url("individual_votes")
-            .into_future()
-            .and_then(move |url| client.json_post::<_>(url, req_body))
-            .and_then(|response| error_for_status(response).map_err(Error::from))
-            .and_then(|mut success| success.json().map_err(Error::from))
+        let url = self.url("individual_votes")?;
+        let response = client.json_post::<_>(url, req_body).await?;
+        let success = error_for_status(response).await.map_err(Error::from)?;
+        success.json().await.map_err(Error::from)
     }
 
     /// Gets a `VoteCount` for the given `epoch`.
-    pub fn get_vote_count(
-        &self,
-        epoch: Epoch,
-    ) -> impl Future<Item = IndividualVotesResponse, Error = Error> {
+    pub async fn get_vote_count(&self, epoch: Epoch) -> Result<IndividualVotesResponse, Error> {
         let client = self.0.clone();
         let query_params = vec![("epoch".into(), format!("{}", epoch.as_u64()))];
-        self.url("vote_count")
-            .into_future()
-            .and_then(move |url| client.json_get(url, query_params))
+        let url = self.url("vote_count")?;
+        client.json_get(url, query_params).await
     }
 }
 

lcli/src/deploy_deposit_contract.rs

@@ -1,5 +1,4 @@
 use clap::ArgMatches;
-use environment::Environment;
 use eth1_test_rig::DepositContract;
 use futures::compat::Future01CompatExt;
 use std::fs::File;
@@ -7,7 +6,7 @@ use std::io::Read;
 use types::EthSpec;
 use web3::{transports::Http, Web3};
 
-pub async fn run<T: EthSpec>(mut env: Environment<T>, matches: &ArgMatches) -> Result<(), String> {
+pub async fn run<T: EthSpec>(matches: &ArgMatches<'_>) -> Result<(), String> {
     let confirmations = matches
         .value_of("confirmations")
         .ok_or_else(|| "Confirmations not specified")?

lcli/src/main.rs

@@ -455,11 +455,9 @@ async fn run<T: EthSpec>(env_builder: EnvironmentBuilder<T>, matches: &ArgMatche
             .unwrap_or_else(|e| error!("Failed to transition blocks: {}", e)),
         ("pretty-hex", Some(matches)) => run_parse_hex::<T>(matches)
             .unwrap_or_else(|e| error!("Failed to pretty print hex: {}", e)),
-        ("deploy-deposit-contract", Some(matches)) => {
-            deploy_deposit_contract::run::<T>(env, matches)
-                .await
-                .unwrap_or_else(|e| error!("Failed to run deploy-deposit-contract command: {}", e))
-        }
+        ("deploy-deposit-contract", Some(matches)) => deploy_deposit_contract::run::<T>(matches)
+            .await
+            .unwrap_or_else(|e| error!("Failed to run deploy-deposit-contract command: {}", e)),
         ("refund-deposit-contract", Some(matches)) => {
             refund_deposit_contract::run::<T>(env, matches)
                 .await