From 8183af5b35423b7d9236c90cda349184038f2f94 Mon Sep 17 00:00:00 2001
From: Patrick Freed <patrick.freed@mongodb.com>
Date: Wed, 4 Aug 2021 17:41:49 -0400
Subject: [PATCH] box futures

---
 src/client/executor.rs           | 72 +++++++++++++++++---------------
 src/operation/find/mod.rs        |  4 +-
 src/test/spec/retryable_reads.rs |  6 +--
 3 files changed, 42 insertions(+), 40 deletions(-)

diff --git a/src/client/executor.rs b/src/client/executor.rs
index 9ffa36a65..72ff5e735 100644
--- a/src/client/executor.rs
+++ b/src/client/executor.rs
@@ -69,42 +69,45 @@ impl Client {
         op: T,
         session: impl Into<Option<&mut ClientSession>>,
     ) -> Result<T::O> {
-        // TODO RUST-9: allow unacknowledged write concerns
-        if !op.is_acknowledged() {
-            return Err(ErrorKind::InvalidArgument {
-                message: "Unacknowledged write concerns are not supported".to_string(),
+        Box::pin(async {
+            // TODO RUST-9: allow unacknowledged write concerns
+            if !op.is_acknowledged() {
+                return Err(ErrorKind::InvalidArgument {
+                    message: "Unacknowledged write concerns are not supported".to_string(),
+                }
+                .into());
             }
-            .into());
-        }
-        match session.into() {
-            Some(session) => {
-                if !Arc::ptr_eq(&self.inner, &session.client().inner) {
-                    return Err(ErrorKind::InvalidArgument {
-                        message: "the session provided to an operation must be created from the \
-                                  same client as the collection/database"
-                            .into(),
+            match session.into() {
+                Some(session) => {
+                    if !Arc::ptr_eq(&self.inner, &session.client().inner) {
+                        return Err(ErrorKind::InvalidArgument {
+                            message: "the session provided to an operation must be created from \
+                                      the same client as the collection/database"
+                                .into(),
+                        }
+                        .into());
                     }
-                    .into());
-                }
 
-                if let Some(SelectionCriteria::ReadPreference(read_preference)) =
-                    op.selection_criteria()
-                {
-                    if session.in_transaction() && read_preference != &ReadPreference::Primary {
-                        return Err(ErrorKind::Transaction {
-                            message: "read preference in a transaction must be primary".into(),
+                    if let Some(SelectionCriteria::ReadPreference(read_preference)) =
+                        op.selection_criteria()
+                    {
+                        if session.in_transaction() && read_preference != &ReadPreference::Primary {
+                            return Err(ErrorKind::Transaction {
+                                message: "read preference in a transaction must be primary".into(),
+                            }
+                            .into());
                         }
-                        .into());
                     }
+                    self.execute_operation_with_retry(op, Some(session)).await
+                }
+                None => {
+                    let mut implicit_session = self.start_implicit_session(&op).await?;
+                    self.execute_operation_with_retry(op, implicit_session.as_mut())
+                        .await
                 }
-                self.execute_operation_with_retry(op, Some(session)).await
-            }
-            None => {
-                let mut implicit_session = self.start_implicit_session(&op).await?;
-                self.execute_operation_with_retry(op, implicit_session.as_mut())
-                    .await
             }
-        }
+        })
+        .await
     }
 
     /// Execute the given operation, returning the implicit session created for it if one was.
@@ -114,10 +117,13 @@ impl Client {
         &self,
         op: T,
     ) -> Result<(T::O, Option<ClientSession>)> {
-        let mut implicit_session = self.start_implicit_session(&op).await?;
-        self.execute_operation_with_retry(op, implicit_session.as_mut())
-            .await
-            .map(|result| (result, implicit_session))
+        Box::pin(async {
+            let mut implicit_session = self.start_implicit_session(&op).await?;
+            self.execute_operation_with_retry(op, implicit_session.as_mut())
+                .await
+                .map(|result| (result, implicit_session))
+        })
+        .await
     }
 
     /// Selects a server and executes the given operation on it, optionally using a provided
diff --git a/src/operation/find/mod.rs b/src/operation/find/mod.rs
index e4cc64782..727f431a0 100644
--- a/src/operation/find/mod.rs
+++ b/src/operation/find/mod.rs
@@ -21,7 +21,7 @@ use super::CursorResponse;
 pub(crate) struct Find<T> {
     ns: Namespace,
     filter: Option<Document>,
-    options: Option<FindOptions>,
+    options: Option<Box<FindOptions>>,
     _phantom: PhantomData<T>,
 }
 
@@ -46,7 +46,7 @@ impl<T> Find<T> {
         Self {
             ns,
             filter,
-            options,
+            options: options.map(Box::new),
             _phantom: Default::default(),
         }
     }
diff --git a/src/test/spec/retryable_reads.rs b/src/test/spec/retryable_reads.rs
index 422bff840..9fa808382 100644
--- a/src/test/spec/retryable_reads.rs
+++ b/src/test/spec/retryable_reads.rs
@@ -1,7 +1,6 @@
 use std::{sync::Arc, time::Duration};
 
 use bson::doc;
-use futures::FutureExt;
 use tokio::sync::RwLockWriteGuard;
 
 use crate::{
@@ -63,10 +62,7 @@ async fn retry_releases_connection() {
     let _fp_guard = client.enable_failpoint(failpoint, None).await.unwrap();
 
     RUNTIME
-        .timeout(
-            Duration::from_secs(1),
-            collection.find_one(doc! {}, None).boxed(),
-        )
+        .timeout(Duration::from_secs(1), collection.find_one(doc! {}, None))
         .await
         .expect("operation should not time out")
         .expect("find should succeed");