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

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
     }
 }