Make HTTP requests cancellable when trying to connect (#8591)

Closes #8585.

Prior to this change, the `http` commands could get stuck for 30s while
attempting to make a connection to a remote server. After this change,
`ctrl+c` works as expected:


![image](https://user-images.githubusercontent.com/26268125/227395505-c2d5b19d-6228-4eac-836f-c0c3426b0c19.png)

To make this work, we perform blocking `ureq` calls in a background
thread and poll the channel while checking `ctrl+c`.

crates/nu-command/src/network/http/client.rs

@@ -13,6 +13,9 @@ use std::collections::HashMap;
 use std::io::BufReader;
 use std::path::PathBuf;
 use std::str::FromStr;
+use std::sync::atomic::AtomicBool;
+use std::sync::mpsc::{self, RecvTimeoutError};
+use std::sync::Arc;
 use std::time::Duration;
 use url::Url;
 
@@ -146,13 +149,11 @@ pub fn send_request(
     request: Request,
     body: Option<Value>,
     content_type: Option<String>,
+    ctrl_c: Option<Arc<AtomicBool>>,
 ) -> Result<Response, ShellErrorOrRequestError> {
     let request_url = request.url().to_string();
-    let error_handler = |err: Error| -> ShellErrorOrRequestError {
-        ShellErrorOrRequestError::RequestError(request_url, err)
-    };
     if body.is_none() {
-        return request.call().map_err(error_handler);
+        return send_cancellable_request(&request_url, Box::new(|| request.call()), ctrl_c);
     }
     let body = body.expect("Should never be none.");
 
@@ -162,11 +163,19 @@ pub fn send_request(
         _ => BodyType::Unknown,
     };
     match body {
-        Value::Binary { val, .. } => request.send_bytes(&val).map_err(error_handler),
-        Value::String { val, .. } => request.send_string(&val).map_err(error_handler),
+        Value::Binary { val, .. } => send_cancellable_request(
+            &request_url,
+            Box::new(move || request.send_bytes(&val)),
+            ctrl_c,
+        ),
+        Value::String { val, .. } => send_cancellable_request(
+            &request_url,
+            Box::new(move || request.send_string(&val)),
+            ctrl_c,
+        ),
         Value::Record { .. } if body_type == BodyType::Json => {
             let data = value_to_json_value(&body);
-            request.send_json(data).map_err(error_handler)
+            send_cancellable_request(&request_url, Box::new(|| request.send_json(data)), ctrl_c)
         }
         Value::Record { cols, vals, .. } if body_type == BodyType::Form => {
             let mut data: Vec<(String, String)> = Vec::with_capacity(cols.len());
@@ -176,12 +185,15 @@ pub fn send_request(
                 data.push((col.clone(), val_string))
             }
 
-            let data = data
-                .iter()
-                .map(|(a, b)| (a.as_str(), b.as_str()))
-                .collect::<Vec<(&str, &str)>>();
-
-            request.send_form(&data[..]).map_err(error_handler)
+            let request_fn = move || {
+                // coerce `data` into a shape that send_form() is happy with
+                let data = data
+                    .iter()
+                    .map(|(a, b)| (a.as_str(), b.as_str()))
+                    .collect::<Vec<(&str, &str)>>();
+                request.send_form(&data)
+            };
+            send_cancellable_request(&request_url, Box::new(request_fn), ctrl_c)
         }
         Value::List { vals, .. } if body_type == BodyType::Form => {
             if vals.len() % 2 != 0 {
@@ -200,12 +212,15 @@ pub fn send_request(
                 })
                 .collect::<Result<Vec<(String, String)>, ShellErrorOrRequestError>>()?;
 
-            let data = data
-                .iter()
-                .map(|(a, b)| (a.as_str(), b.as_str()))
-                .collect::<Vec<(&str, &str)>>();
-
-            request.send_form(&data).map_err(error_handler)
+            let request_fn = move || {
+                // coerce `data` into a shape that send_form() is happy with
+                let data = data
+                    .iter()
+                    .map(|(a, b)| (a.as_str(), b.as_str()))
+                    .collect::<Vec<(&str, &str)>>();
+                request.send_form(&data)
+            };
+            send_cancellable_request(&request_url, Box::new(request_fn), ctrl_c)
         }
         _ => Err(ShellErrorOrRequestError::ShellError(ShellError::IOError(
             "unsupported body input".into(),
@@ -213,6 +228,46 @@ pub fn send_request(
     }
 }
 
+// Helper method used to make blocking HTTP request calls cancellable with ctrl+c
+// ureq functions can block for a long time (default 30s?) while attempting to make an HTTP connection
+fn send_cancellable_request(
+    request_url: &str,
+    request_fn: Box<dyn FnOnce() -> Result<Response, Error> + Sync + Send>,
+    ctrl_c: Option<Arc<AtomicBool>>,
+) -> Result<Response, ShellErrorOrRequestError> {
+    let (tx, rx) = mpsc::channel::<Result<Response, Error>>();
+
+    // Make the blocking request on a background thread...
+    std::thread::Builder::new()
+        .name("HTTP requester".to_string())
+        .spawn(move || {
+            let ret = request_fn();
+            let _ = tx.send(ret); // may fail if the user has cancelled the operation
+        })
+        .expect("Failed to create thread");
+
+    // ...and poll the channel for responses
+    loop {
+        if nu_utils::ctrl_c::was_pressed(&ctrl_c) {
+            // Return early and give up on the background thread. The connection will either time out or be disconnected
+            return Err(ShellErrorOrRequestError::ShellError(
+                ShellError::InterruptedByUser { span: None },
+            ));
+        }
+
+        // 100ms wait time chosen arbitrarily
+        match rx.recv_timeout(Duration::from_millis(100)) {
+            Ok(result) => {
+                return result.map_err(|e| {
+                    ShellErrorOrRequestError::RequestError(request_url.to_string(), e)
+                });
+            }
+            Err(RecvTimeoutError::Timeout) => continue,
+            Err(RecvTimeoutError::Disconnected) => panic!("http response channel disconnected"),
+        }
+    }
+}
+
 pub fn request_set_timeout(
     timeout: Option<Value>,
     mut request: Request,

crates/nu-command/src/network/http/delete.rs

@@ -184,6 +184,7 @@ fn helper(
     args: Arguments,
 ) -> Result<PipelineData, ShellError> {
     let span = args.url.span()?;
+    let ctrl_c = engine_state.ctrlc.clone();
     let (requested_url, _) = http_parse_url(call, span, args.url)?;
 
     let client = http_client(args.insecure);
@@ -193,7 +194,7 @@ fn helper(
     request = request_add_authorization_header(args.user, args.password, request);
     request = request_add_custom_headers(args.headers, request)?;
 
-    let response = send_request(request, args.data, args.content_type);
+    let response = send_request(request, args.data, args.content_type, ctrl_c);
 
     let request_flags = RequestFlags {
         raw: args.raw,

crates/nu-command/src/network/http/get.rs

@@ -163,6 +163,7 @@ fn helper(
     args: Arguments,
 ) -> Result<PipelineData, ShellError> {
     let span = args.url.span()?;
+    let ctrl_c = engine_state.ctrlc.clone();
     let (requested_url, _) = http_parse_url(call, span, args.url)?;
 
     let client = http_client(args.insecure);
@@ -172,7 +173,7 @@ fn helper(
     request = request_add_authorization_header(args.user, args.password, request);
     request = request_add_custom_headers(args.headers, request)?;
 
-    let response = send_request(request, None, None);
+    let response = send_request(request, None, None, ctrl_c);
 
     let request_flags = RequestFlags {
         raw: args.raw,

crates/nu-command/src/network/http/head.rs

@@ -1,3 +1,6 @@
+use std::sync::atomic::AtomicBool;
+use std::sync::Arc;
+
 use nu_engine::CallExt;
 use nu_protocol::ast::Call;
 use nu_protocol::engine::{Command, EngineState, Stack};
@@ -126,13 +129,18 @@ fn run_head(
         password: call.get_flag(engine_state, stack, "password")?,
         timeout: call.get_flag(engine_state, stack, "max-time")?,
     };
+    let ctrl_c = engine_state.ctrlc.clone();
 
-    helper(call, args)
+    helper(call, args, ctrl_c)
 }
 
 // Helper function that actually goes to retrieve the resource from the url given
 // The Option<String> return a possible file extension which can be used in AutoConvert commands
-fn helper(call: &Call, args: Arguments) -> Result<PipelineData, ShellError> {
+fn helper(
+    call: &Call,
+    args: Arguments,
+    ctrlc: Option<Arc<AtomicBool>>,
+) -> Result<PipelineData, ShellError> {
     let span = args.url.span()?;
     let (requested_url, _) = http_parse_url(call, span, args.url)?;
 
@@ -143,7 +151,7 @@ fn helper(call: &Call, args: Arguments) -> Result<PipelineData, ShellError> {
     request = request_add_authorization_header(args.user, args.password, request);
     request = request_add_custom_headers(args.headers, request)?;
 
-    let response = send_request(request, None, None);
+    let response = send_request(request, None, None, ctrlc);
     request_handle_response_headers(span, response)
 }
 

crates/nu-command/src/network/http/patch.rs

@@ -174,6 +174,7 @@ fn helper(
     args: Arguments,
 ) -> Result<PipelineData, ShellError> {
     let span = args.url.span()?;
+    let ctrl_c = engine_state.ctrlc.clone();
     let (requested_url, _) = http_parse_url(call, span, args.url)?;
 
     let client = http_client(args.insecure);
@@ -183,7 +184,7 @@ fn helper(
     request = request_add_authorization_header(args.user, args.password, request);
     request = request_add_custom_headers(args.headers, request)?;
 
-    let response = send_request(request, Some(args.data), args.content_type);
+    let response = send_request(request, Some(args.data), args.content_type, ctrl_c);
 
     let request_flags = RequestFlags {
         raw: args.raw,

crates/nu-command/src/network/http/post.rs

@@ -174,6 +174,7 @@ fn helper(
     args: Arguments,
 ) -> Result<PipelineData, ShellError> {
     let span = args.url.span()?;
+    let ctrl_c = engine_state.ctrlc.clone();
     let (requested_url, _) = http_parse_url(call, span, args.url)?;
 
     let client = http_client(args.insecure);
@@ -183,7 +184,7 @@ fn helper(
     request = request_add_authorization_header(args.user, args.password, request);
     request = request_add_custom_headers(args.headers, request)?;
 
-    let response = send_request(request, Some(args.data), args.content_type);
+    let response = send_request(request, Some(args.data), args.content_type, ctrl_c);
 
     let request_flags = RequestFlags {
         raw: args.raw,

crates/nu-command/src/network/http/put.rs

@@ -174,6 +174,7 @@ fn helper(
     args: Arguments,
 ) -> Result<PipelineData, ShellError> {
     let span = args.url.span()?;
+    let ctrl_c = engine_state.ctrlc.clone();
     let (requested_url, _) = http_parse_url(call, span, args.url)?;
 
     let client = http_client(args.insecure);
@@ -183,7 +184,7 @@ fn helper(
     request = request_add_authorization_header(args.user, args.password, request);
     request = request_add_custom_headers(args.headers, request)?;
 
-    let response = send_request(request, Some(args.data), args.content_type);
+    let response = send_request(request, Some(args.data), args.content_type, ctrl_c);
 
     let request_flags = RequestFlags {
         raw: args.raw,

crates/nu-protocol/src/shell_error.rs

@@ -1056,6 +1056,13 @@ pub enum ShellError {
         #[label("Could not access '{column_name}' on this record")]
         span: Span,
     },
+
+    /// Operation interrupted by user
+    #[error("Operation interrupted by user")]
+    InterruptedByUser {
+        #[label("This operation was interrupted")]
+        span: Option<Span>,
+    },
 }
 
 impl From<std::io::Error> for ShellError {