conditional compilation for async roundtripper

Signed-off-by: Gregory Hill <[email protected]>

Author: gregdhill

Cargo.toml

@@ -9,6 +9,10 @@ documentation = "https://docs.rs/jsonrpc/"
 description = "Rust support for the JSON-RPC 2.0 protocol"
 keywords = [ "protocol", "json", "http", "jsonrpc" ]
 readme	 = "README.md"
+edition = "2018"
+
+[features]
+async = []
 
 [lib]
 name = "jsonrpc"

src/client.rs

@@ -18,18 +18,18 @@
 //! and parsing responses
 //!
 
-use std::{error, io};
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
+use std::{error, io};
 
-use serde;
 use base64;
 use http;
+use serde;
 use serde_json;
 
 use super::{Request, Response};
-use util::HashableValue;
-use error::Error;
+use crate::error::Error;
+use crate::util::HashableValue;
 
 /// An interface for an HTTP roundtripper that handles HTTP requests.
 pub trait HttpRoundTripper {
@@ -38,11 +38,27 @@ pub trait HttpRoundTripper {
     /// The type for errors generated by the roundtripper.
     type Err: error::Error;
 
-    /// Make an HTTP request.  In practice only POST request will be made.
+    /// Make a synchronous HTTP request. In practice only POST request will be made.
+    #[cfg(not(feature = "async"))]
     fn request(
         &self,
-        http::Request<&[u8]>,
+        _request: http::Request<&[u8]>,
     ) -> Result<http::Response<Self::ResponseBody>, Self::Err>;
+
+    /// Make an asynchronous HTTP request. In practice only POST request will be made.
+    #[cfg(feature = "async")]
+    fn request<'life>(
+        &'life self,
+        _request: http::Request<&'life [u8]>,
+    ) -> std::pin::Pin<
+        Box<
+            dyn std::future::Future<Output = Result<http::Response<Self::ResponseBody>, Self::Err>>
+                + Send
+                + 'life,
+        >,
+    >
+    where
+        Self: Sync + 'life;
 }
 
 /// A handle to a remote JSONRPC server
@@ -54,7 +70,21 @@ pub struct Client<R: HttpRoundTripper> {
     nonce: Arc<Mutex<u64>>,
 }
 
-impl<Rt: HttpRoundTripper + 'static> Client<Rt> {
+#[cfg(not(feature = "async"))]
+macro_rules! maybe_async_fn {
+    ($($tokens:tt)*) => {
+        $($tokens)*
+    };
+}
+
+#[cfg(feature = "async")]
+macro_rules! maybe_async_fn {
+    ($(#[$($meta:meta)*])* $vis:vis $ident:ident $($tokens:tt)*) => {
+        $(#[$($meta)*])* $vis async $ident $($tokens)*
+    };
+}
+
+impl<Rt: HttpRoundTripper + 'static + Sync> Client<Rt> {
     /// Creates a new client
     pub fn new(
         roundtripper: Rt,
@@ -74,104 +104,139 @@ impl<Rt: HttpRoundTripper + 'static> Client<Rt> {
         }
     }
 
-    /// Make a request and deserialize the response
-    pub fn do_rpc<T: for<'a> serde::de::Deserialize<'a>>(
-        &self,
-        rpc_name: &str,
-        args: &[serde_json::value::Value],
-    ) -> Result<T, Error> {
-        let request = self.build_request(rpc_name, args);
-        let response = self.send_request(&request)?;
+    maybe_async_fn! {
+        /// Make a request and deserialize the response
+        pub fn do_rpc<T: for<'a> serde::de::Deserialize<'a>>(
+            &self,
+            rpc_name: &str,
+            args: &[serde_json::value::Value],
+        ) -> Result<T, Error> {
+            let request = self.build_request(rpc_name, args);
+
+            #[cfg(not(feature = "async"))]
+            let response = self.send_request(&request)?;
 
-        Ok(response.into_result()?)
+            #[cfg(feature = "async")]
+            let response = self.send_request(&request).await?;
+
+            Ok(response.into_result()?)
+        }
     }
 
-    /// The actual send logic used by both [send_request] and [send_batch].
-    fn send_raw<B, R>(&self, body: &B) -> Result<R, Error>
-    where
-        B: serde::ser::Serialize,
-        R: for<'de> serde::de::Deserialize<'de>,
-    {
-        // Build request
-        let request_raw = serde_json::to_vec(body)?;
-
-        // Send request
-        let mut request_builder = http::Request::post(&self.url);
-        request_builder.header("Content-Type", "application/json-rpc");
-
-        // Set Authorization header
-        if let Some(ref user) = self.user {
-            let mut auth = user.clone();
-            auth.push(':');
-            if let Some(ref pass) = self.pass {
-                auth.push_str(&pass[..]);
+    maybe_async_fn! {
+        /// The actual send logic used by both [send_request] and [send_batch].
+        fn send_raw<B, R>(&self, body: &B) -> Result<R, Error>
+        where
+            B: serde::ser::Serialize,
+            R: for<'de> serde::de::Deserialize<'de>,
+        {
+            // Build request
+            let request_raw = serde_json::to_vec(body)?;
+
+            // Send request
+            let mut request_builder = http::Request::post(&self.url);
+            request_builder.header("Content-Type", "application/json-rpc");
+
+            // Set Authorization header
+            if let Some(ref user) = self.user {
+                let mut auth = user.clone();
+                auth.push(':');
+                if let Some(ref pass) = self.pass {
+                    auth.push_str(&pass[..]);
+                }
+                let value = format!("Basic {}", &base64::encode(auth.as_bytes()));
+                request_builder.header("Authorization", value);
             }
-            let value = format!("Basic {}", &base64::encode(auth.as_bytes()));
-            request_builder.header("Authorization", value);
-        }
 
-        // Errors only on invalid header or builder reuse.
-        let http_request = request_builder.body(&request_raw[..]).unwrap();
+            // Errors only on invalid header or builder reuse.
+            let http_request = request_builder.body(&request_raw[..]).unwrap();
 
-        let http_response =
-            self.roundtripper.request(http_request).map_err(|e| Error::Http(Box::new(e)))?;
+            #[cfg(not(feature = "async"))]
+            let http_response = self
+                .roundtripper
+                .request(http_request)
+                .map_err(|e| Error::Http(Box::new(e)))?;
 
-        // nb we ignore stream.status since we expect the body
-        // to contain information about any error
-        Ok(serde_json::from_reader(http_response.into_body())?)
-    }
+            #[cfg(feature = "async")]
+            let http_response = self
+                .roundtripper
+                .request(http_request).await
+                .map_err(|e| Error::Http(Box::new(e)))?;
 
-    /// Sends a request to a client
-    pub fn send_request(&self, request: &Request) -> Result<Response, Error> {
-        let response: Response = self.send_raw(&request)?;
-        if response.jsonrpc != None && response.jsonrpc != Some(From::from("2.0")) {
-            return Err(Error::VersionMismatch);
-        }
-        if response.id != request.id {
-            return Err(Error::NonceMismatch);
+
+            // nb we ignore stream.status since we expect the body
+            // to contain information about any error
+            Ok(serde_json::from_reader(http_response.into_body())?)
         }
-        Ok(response)
     }
 
-    /// Sends a batch of requests to the client.  The return vector holds the response
-    /// for the request at the corresponding index.  If no response was provided, it's [None].
-    ///
-    /// Note that the requests need to have valid IDs, so it is advised to create the requests
-    /// with [build_request].
-    pub fn send_batch(&self, requests: &[Request]) -> Result<Vec<Option<Response>>, Error> {
-        if requests.len() < 1 {
-            return Err(Error::EmptyBatch);
-        }
+    maybe_async_fn! {
+        /// Sends a request to a client
+        pub fn send_request<'a, 'b>(&self, request: &Request<'a, 'b>) -> Result<Response, Error> {
+            #[cfg(not(feature = "async"))]
+            let response: Response = self.send_raw(&request)?;
 
-        // If the request body is invalid JSON, the response is a single response object.
-        // We ignore this case since we are confident we are producing valid JSON.
-        let responses: Vec<Response> = self.send_raw(&requests)?;
-        if responses.len() > requests.len() {
-            return Err(Error::WrongBatchResponseSize);
+            #[cfg(feature = "async")]
+            let response: Response = self.send_raw(&request).await?;
+            
+            if response.jsonrpc != None && response.jsonrpc != Some(From::from("2.0")) {
+                return Err(Error::VersionMismatch);
+            }
+            if response.id != request.id {
+                return Err(Error::NonceMismatch);
+            }
+            Ok(response)
         }
+    }
 
-        // To prevent having to clone responses, we first copy all the IDs so we can reference
-        // them easily. IDs can only be of JSON type String or Number (or Null), so cloning
-        // should be inexpensive and require no allocations as Numbers are more common.
-        let ids: Vec<serde_json::Value> = responses.iter().map(|r| r.id.clone()).collect();
-        // First index responses by ID and catch duplicate IDs.
-        let mut resp_by_id = HashMap::new();
-        for (id, resp) in ids.iter().zip(responses.into_iter()) {
-            if let Some(dup) = resp_by_id.insert(HashableValue(&id), resp) {
-                return Err(Error::BatchDuplicateResponseId(dup.id));
+    maybe_async_fn! {
+        /// Sends a batch of requests to the client.  The return vector holds the response
+        /// for the request at the corresponding index.  If no response was provided, it's [None].
+        ///
+        /// Note that the requests need to have valid IDs, so it is advised to create the requests
+        /// with [build_request].
+        pub fn send_batch<'a, 'b>(&self, requests: &[Request<'a, 'b>]) -> Result<Vec<Option<Response>>, Error> {
+            if requests.len() < 1 {
+                return Err(Error::EmptyBatch);
             }
-        }
-        // Match responses to the requests.
-        let results =
-            requests.into_iter().map(|r| resp_by_id.remove(&HashableValue(&r.id))).collect();
-
-        // Since we're also just producing the first duplicate ID, we can also just produce the
-        // first incorrect ID in case there are multiple.
-        if let Some(incorrect) = resp_by_id.into_iter().nth(0) {
-            return Err(Error::WrongBatchResponseId(incorrect.1.id));
-        }
 
-        Ok(results)
+            // If the request body is invalid JSON, the response is a single response object.
+            // We ignore this case since we are confident we are producing valid JSON.
+            #[cfg(not(feature = "async"))]
+            let responses: Vec<Response> = self.send_raw(&requests)?;
+
+            #[cfg(feature = "async")]
+            let responses: Vec<Response> = self.send_raw(&requests).await?;
+
+            if responses.len() > requests.len() {
+                return Err(Error::WrongBatchResponseSize);
+            }
+
+            // To prevent having to clone responses, we first copy all the IDs so we can reference
+            // them easily. IDs can only be of JSON type String or Number (or Null), so cloning
+            // should be inexpensive and require no allocations as Numbers are more common.
+            let ids: Vec<serde_json::Value> = responses.iter().map(|r| r.id.clone()).collect();
+            // First index responses by ID and catch duplicate IDs.
+            let mut resp_by_id = HashMap::new();
+            for (id, resp) in ids.iter().zip(responses.into_iter()) {
+                if let Some(dup) = resp_by_id.insert(HashableValue(&id), resp) {
+                    return Err(Error::BatchDuplicateResponseId(dup.id));
+                }
+            }
+            // Match responses to the requests.
+            let results = requests
+                .into_iter()
+                .map(|r| resp_by_id.remove(&HashableValue(&r.id)))
+                .collect();
+
+            // Since we're also just producing the first duplicate ID, we can also just produce the
+            // first incorrect ID in case there are multiple.
+            if let Some(incorrect) = resp_by_id.into_iter().nth(0) {
+                return Err(Error::WrongBatchResponseId(incorrect.1.id));
+            }
+
+            Ok(results)
+        }
     }
 
     /// Builds a request
@@ -206,12 +271,30 @@ mod tests {
         type ResponseBody = io::Empty;
         type Err = io::Error;
 
+        #[cfg(not(feature = "async"))]
         fn request(
             &self,
             _: http::Request<&[u8]>,
         ) -> Result<http::Response<Self::ResponseBody>, Self::Err> {
             Err(io::ErrorKind::Other.into())
         }
+
+        #[cfg(feature = "async")]
+        fn request<'life>(
+            &'life self,
+            request: http::Request<&[u8]>,
+        ) -> std::pin::Pin<
+            Box<
+                dyn std::future::Future<
+                        Output = Result<http::Response<Self::ResponseBody>, Self::Err>,
+                    > + Send
+                    + 'life,
+            >,
+        >
+        where
+            Self: Sync + 'life {
+                Box::pin(async { Err(io::ErrorKind::Other.into()) })
+            }
     }
 
     #[test]

src/error.rs

@@ -21,7 +21,7 @@ use std::{error, fmt};
 
 use serde_json;
 
-use Response;
+use crate::Response;
 
 /// A library error
 #[derive(Debug)]