conditional compilation for async roundtripper

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 {
@@ -38,30 +38,53 @@ 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.
     fn request(
         &self,
-        http::Request<&[u8]>,
+        _request: http::Request<Vec<u8>>,
     ) -> Result<http::Response<Self::ResponseBody>, Self::Err>;
 }
 
+/// An interface for an asynchronous HTTP roundtripper that handles HTTP requests.
+#[cfg(feature = "async")]
+pub trait AsyncHttpRoundTripper {
+    /// The type of the http::Response body.
+    type ResponseBody: io::Read;
+    /// The type for errors generated by the roundtripper.
+    type Err: error::Error;
+
+    /// Make an asynchronous HTTP request. In practice only POST request will be made.
+    fn request<'life>(
+        &'life self,
+        _request: http::Request<Vec<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
-pub struct Client<R: HttpRoundTripper> {
+pub struct Client<R> {
     url: String,
     user: Option<String>,
     pass: Option<String>,
     roundtripper: R,
     nonce: Arc<Mutex<u64>>,
 }
 
-impl<Rt: HttpRoundTripper + 'static> Client<Rt> {
+impl<R> Client<R> {
     /// Creates a new client
     pub fn new(
-        roundtripper: Rt,
+        roundtripper: R,
         url: String,
         user: Option<String>,
         pass: Option<String>,
-    ) -> Client<Rt> {
+    ) -> Client<R> {
         // Check that if we have a password, we have a username; other way around is ok
         debug_assert!(pass.is_none() || user.is_some());
 
@@ -74,23 +97,25 @@ impl<Rt: HttpRoundTripper + 'static> Client<Rt> {
         }
     }
 
-    /// Make a request and deserialize the response
-    pub fn do_rpc<T: for<'a> serde::de::Deserialize<'a>>(
+    /// Builds a request
+    pub fn build_request<'a, 'b>(
         &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)?;
-
-        Ok(response.into_result()?)
+        name: &'a str,
+        params: &'b [serde_json::Value],
+    ) -> Request<'a, 'b> {
+        let mut nonce = self.nonce.lock().unwrap();
+        *nonce += 1;
+        Request {
+            method: name,
+            params: params,
+            id: From::from(*nonce),
+            jsonrpc: Some("2.0"),
+        }
     }
 
-    /// The actual send logic used by both [send_request] and [send_batch].
-    fn send_raw<B, R>(&self, body: &B) -> Result<R, Error>
+    fn build_http_request<B>(&self, body: &B) -> Result<http::Request<Vec<u8>>, Error>
     where
         B: serde::ser::Serialize,
-        R: for<'de> serde::de::Deserialize<'de>,
     {
         // Build request
         let request_raw = serde_json::to_vec(body)?;
@@ -111,89 +136,179 @@ impl<Rt: HttpRoundTripper + 'static> Client<Rt> {
         }
 
         // Errors only on invalid header or builder reuse.
-        let http_request = request_builder.body(&request_raw[..]).unwrap();
+        Ok(request_builder.body(request_raw).unwrap())
+    }
 
-        let http_response =
-            self.roundtripper.request(http_request).map_err(|e| Error::Http(Box::new(e)))?;
+    /// Accessor for the last-used nonce
+    pub fn last_nonce(&self) -> u64 {
+        *self.nonce.lock().unwrap()
+    }
+}
+
+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)?;
+        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>,
+    {
+        let http_request = self.build_http_request(body)?;
+
+        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())?)
     }
 
     /// Sends a request to a client
-    pub fn send_request(&self, request: &Request) -> Result<Response, Error> {
+    pub fn send_request<'a, 'b>(&self, request: &Request<'a, 'b>) -> 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);
-        }
-        Ok(response)
+        validate_response(request, 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].
+    /// 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> {
+    pub fn send_batch<'a, 'b>(
+        &self,
+        requests: &[Request<'a, 'b>],
+    ) -> Result<Vec<Option<Response>>, Error> {
         if requests.len() < 1 {
             return Err(Error::EmptyBatch);
         }
 
         // 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);
-        }
 
-        // 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));
-        }
+        validate_batch_response(requests, responses)
+    }
+}
 
-        Ok(results)
+#[cfg(feature = "async")]
+impl<Rt: AsyncHttpRoundTripper + 'static + Sync> Client<Rt> {
+    /// Make a request and deserialize the response
+    pub async fn do_rpc_async<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_async(&request).await?;
+        Ok(response.into_result()?)
     }
 
-    /// Builds a request
-    pub fn build_request<'a, 'b>(
+    /// The actual send logic used by both [send_request] and [send_batch].
+    async fn send_raw_async<B, R>(&self, body: &B) -> Result<R, Error>
+    where
+        B: serde::ser::Serialize,
+        R: for<'de> serde::de::Deserialize<'de>,
+    {
+        let http_request = self.build_http_request(body)?;
+
+        let http_response = self
+            .roundtripper
+            .request(http_request)
+            .await
+            .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())?)
+    }
+
+    /// Sends a request to a client
+    pub async fn send_request_async<'a, 'b>(
         &self,
-        name: &'a str,
-        params: &'b [serde_json::Value],
-    ) -> Request<'a, 'b> {
-        let mut nonce = self.nonce.lock().unwrap();
-        *nonce += 1;
-        Request {
-            method: name,
-            params: params,
-            id: From::from(*nonce),
-            jsonrpc: Some("2.0"),
+        request: &Request<'a, 'b>,
+    ) -> Result<Response, Error> {
+        let response: Response = self.send_raw_async(&request).await?;
+        validate_response(request, 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 async fn send_batch_async<'a, 'b>(
+        &self,
+        requests: &[Request<'a, 'b>],
+    ) -> Result<Vec<Option<Response>>, Error> {
+        if requests.len() < 1 {
+            return Err(Error::EmptyBatch);
+        }
+
+        // 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_async(&requests).await?;
+
+        validate_batch_response(requests, responses)
+    }
+}
+
+fn validate_response<'a, 'b>(
+    request: &Request<'a, 'b>,
+    response: Response,
+) -> Result<Response, Error> {
+    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)
+}
+
+fn validate_batch_response<'a, 'b>(
+    requests: &[Request<'a, 'b>],
+    responses: Vec<Response>,
+) -> Result<Vec<Option<Response>>, Error> {
+    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();
 
-    /// Accessor for the last-used nonce
-    pub fn last_nonce(&self) -> u64 {
-        *self.nonce.lock().unwrap()
+    // 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)
 }
 
 #[cfg(test)]
@@ -208,7 +323,7 @@ mod tests {
 
         fn request(
             &self,
-            _: http::Request<&[u8]>,
+            _: http::Request<Vec<u8>>,
         ) -> Result<http::Response<Self::ResponseBody>, Self::Err> {
             Err(io::ErrorKind::Other.into())
         }

src/error.rs

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