refactor(async)!: remove async-std dependency, allow custom runtime

Author: praveenperera

Cargo.toml

@@ -23,7 +23,9 @@ hex = { version = "0.2", package = "hex-conservative" }
 log = "^0.4"
 minreq = { version = "2.11.0", features = ["json-using-serde"], optional = true }
 reqwest = { version = "0.11",  features = ["json"], default-features = false, optional = true }
-async-std = { version = "1.13.0", optional = true }
+
+# default async runtime
+tokio = { version = "1", features = ["time"], optional = true }
 
 [dev-dependencies]
 serde_json = "1.0"
@@ -32,13 +34,15 @@ electrsd = { version = "0.28.0", features = ["legacy", "esplora_a33e97e1", "bitc
 lazy_static = "1.4.0"
 
 [features]
-default = ["blocking", "async", "async-https"]
+default = ["blocking", "async", "async-https", "tokio"]
 blocking = ["minreq", "minreq/proxy"]
 blocking-https = ["blocking", "minreq/https"]
 blocking-https-rustls = ["blocking", "minreq/https-rustls"]
 blocking-https-native = ["blocking", "minreq/https-native"]
 blocking-https-bundled = ["blocking", "minreq/https-bundled"]
-async = ["async-std", "reqwest", "reqwest/socks"]
+
+tokio = ["dep:tokio"]
+async = ["reqwest", "reqwest/socks", "tokio?/time"]
 async-https = ["async", "reqwest/default-tls"]
 async-https-native = ["async", "reqwest/native-tls"]
 async-https-rustls = ["async", "reqwest/rustls-tls"]

src/async.rs

@@ -11,8 +11,8 @@
 
 //! Esplora by way of `reqwest` HTTP client.
 
-use async_std::task;
 use std::collections::HashMap;
+use std::marker::PhantomData;
 use std::str::FromStr;
 
 use bitcoin::consensus::{deserialize, serialize, Decodable, Encodable};
@@ -35,16 +35,19 @@ use crate::{
 };
 
 #[derive(Debug, Clone)]
-pub struct AsyncClient {
+pub struct AsyncClient<S = DefaultSleeper> {
     /// The URL of the Esplora Server.
     url: String,
     /// The inner [`reqwest::Client`] to make HTTP requests.
     client: Client,
     /// Number of times to retry a request
     max_retries: usize,
+
+    /// Marker for the type of sleeper used
+    marker: PhantomData<S>,
 }
 
-impl AsyncClient {
+impl<S: Sleeper> AsyncClient<S> {
     /// Build an async client from a builder
     pub fn from_builder(builder: Builder) -> Result<Self, Error> {
         let mut client_builder = Client::builder();
@@ -75,15 +78,16 @@ impl AsyncClient {
             url: builder.base_url,
             client: client_builder.build()?,
             max_retries: builder.max_retries,
+            marker: PhantomData,
         })
     }
 
-    /// Build an async client from the base url and [`Client`]
     pub fn from_client(url: String, client: Client) -> Self {
         AsyncClient {
             url,
             client,
             max_retries: crate::DEFAULT_MAX_RETRIES,
+            marker: PhantomData,
         }
     }
 
@@ -460,7 +464,7 @@ impl AsyncClient {
         loop {
             match self.client.get(url).send().await? {
                 resp if attempts < self.max_retries && is_status_retryable(resp.status()) => {
-                    task::sleep(delay).await;
+                    S::sleep(delay).await;
                     attempts += 1;
                     delay *= 2;
                 }
@@ -473,3 +477,20 @@ impl AsyncClient {
 fn is_status_retryable(status: reqwest::StatusCode) -> bool {
     RETRYABLE_ERROR_CODES.contains(&status.as_u16())
 }
+
+pub trait Sleeper: 'static {
+    type Sleep: std::future::Future<Output = ()>;
+    fn sleep(dur: std::time::Duration) -> Self::Sleep;
+}
+
+#[derive(Debug, Clone, Copy)]
+pub struct DefaultSleeper;
+
+#[cfg(any(test, feature = "tokio"))]
+impl Sleeper for DefaultSleeper {
+    type Sleep = tokio::time::Sleep;
+
+    fn sleep(dur: std::time::Duration) -> Self::Sleep {
+        tokio::time::sleep(dur)
+    }
+}

src/lib.rs

@@ -26,7 +26,7 @@
 //! Here is an example of how to create an asynchronous client.
 //!
 //! ```no_run
-//! # #[cfg(feature = "async")]
+//! # #[cfg(all(feature = "async", feature = "tokio"))]
 //! # {
 //! use esplora_client::Builder;
 //! let builder = Builder::new("https://blockstream.info/testnet/api");
@@ -71,8 +71,10 @@ use std::fmt;
 use std::num::TryFromIntError;
 use std::time::Duration;
 
-pub mod api;
+#[cfg(feature = "async")]
+pub use r#async::Sleeper;
 
+pub mod api;
 #[cfg(feature = "async")]
 pub mod r#async;
 #[cfg(feature = "blocking")]
@@ -178,11 +180,18 @@ impl Builder {
         BlockingClient::from_builder(self)
     }
 
-    // Build an asynchronous client from builder
-    #[cfg(feature = "async")]
+    /// Build an asynchronous client from builder
+    #[cfg(all(feature = "async", feature = "tokio"))]
     pub fn build_async(self) -> Result<AsyncClient, Error> {
         AsyncClient::from_builder(self)
     }
+
+    /// Build an asynchronous client from builder where the returned client uses a
+    /// user-defined [`Sleeper`].
+    #[cfg(feature = "async")]
+    pub fn build_async_with_sleeper<S: Sleeper>(self) -> Result<AsyncClient<S>, Error> {
+        AsyncClient::from_builder(self)
+    }
 }
 
 /// Errors that can happen during a request to `Esplora` servers.
@@ -320,8 +329,15 @@ mod test {
         let blocking_client = builder.build_blocking();
 
         let builder_async = Builder::new(&format!("http://{}", esplora_url));
+
+        #[cfg(feature = "tokio")]
         let async_client = builder_async.build_async().unwrap();
 
+        #[cfg(not(feature = "tokio"))]
+        let async_client = builder_async
+            .build_async_with_sleeper::<r#async::DefaultSleeper>()
+            .unwrap();
+
         (blocking_client, async_client)
     }