Unable to send BoxableIo safely between threads

[nevi-me]

I have an application that uses tiberius and tower-grpc (with tower-hyper). Before tower-grpc was updated to 0.1, I used to use wait() as a work-around on my connection like below:

/// Create connection result, waiting for the future to complete
fn connect(
) -> Result<SqlConnection<Box<dyn BoxableIo>>Error> {
    let conn_str = "server=tcp:localhost,1433;integratedSecurity=false;".to_owned();

    SqlConnection::connect(conn_str.as_str()).wait()
}

Ever since the upgrade, wait()ing blocks indefinitely, so I'm forced to remove it. However, my code now can't compile because *const tiberius::query::QueryStream<Box<dyn tiberius::BoxableIo>> cannot be sent safely between threads.

`*const tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>` cannot be sent between threads safely
within `futures::future::and_then::AndThen<futures::future::and_then::AndThen<std::boxed::Box<dyn futures::future::Future<Item = tiberius::SqlConnection<std::boxed::Box<dyn tiberius::BoxableIo>>, Error = tiberius::Error> + std::marker::Send>, futures::future::map::Map<futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>, [closure@src\database\mssql.rs:68:18: 68:59]>, [closure@src\database\mssql.rs:61:19: 69:10 value:_]>, std::result::Result<std::option::Option<std::string::String>, tiberius::Error>, [closure@src\database\mssql.rs:71:19: 71:54]>`, the trait `std::marker::Send` is not implemented for `*const tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>`
required because it appears within the type `std::marker::PhantomData<*const tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>`
required because it appears within the type `tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>`
required because it appears within the type `tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>`
required because it appears within the type `futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>`
required because it appears within the type `futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>`
required because it appears within the type `futures::future::map::Map<futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>, [closure@src\database\mssql.rs:68:18: 68:59]>`
required because it appears within the type `futures::future::chain::Chain<std::boxed::Box<dyn futures::future::Future<Item = tiberius::SqlConnection<std::boxed::Box<dyn tiberius::BoxableIo>>, Error = tiberius::Error> + std::marker::Send>, futures::future::map::Map<futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>, [closure@src\database\mssql.rs:68:18: 68:59]>, [closure@src\database\mssql.rs:61:19: 69:10 value:_]>`
required because it appears within the type `futures::future::and_then::AndThen<std::boxed::Box<dyn futures::future::Future<Item = tiberius::SqlConnection<std::boxed::Box<dyn tiberius::BoxableIo>>, Error = tiberius::Error> + std::marker::Send>, futures::future::map::Map<futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>, [closure@src\database\mssql.rs:68:18: 68:59]>, [closure@src\database\mssql.rs:61:19: 69:10 value:_]>`
required because it appears within the type `futures::future::chain::Chain<futures::future::and_then::AndThen<std::boxed::Box<dyn futures::future::Future<Item = tiberius::SqlConnection<std::boxed::Box<dyn tiberius::BoxableIo>>, Error = tiberius::Error> + std::marker::Send>, futures::future::map::Map<futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>, [closure@src\database\mssql.rs:68:18: 68:59]>, [closure@src\database\mssql.rs:61:19: 69:10 value:_]>, futures::future::result_::FutureResult<std::option::Option<std::string::String>, tiberius::Error>, [closure@src\database\mssql.rs:71:19: 71:54]>`
required because it appears within the type `futures::future::and_then::AndThen<futures::future::and_then::AndThen<std::boxed::Box<dyn futures::future::Future<Item = tiberius::SqlConnection<std::boxed::Box<dyn tiberius::BoxableIo>>, Error = tiberius::Error> + std::marker::Send>, futures::future::map::Map<futures_state_stream::Collect<futures_state_stream::Map<tiberius::stmt::QueryResult<tiberius::stmt::StmtStream<std::boxed::Box<dyn tiberius::BoxableIo>, tiberius::query::QueryStream<std::boxed::Box<dyn tiberius::BoxableIo>>>>, [closure@src\database\mssql.rs:66:18: 66:83]>>, [closure@src\database\mssql.rs:68:18: 68:59]>, [closure@src\database\mssql.rs:61:19: 69:10 value:_]>, std::result::Result<std::option::Option<std::string::String>, tiberius::Error>, [closure@src\database\mssql.rs:71:19: 71:54]>`
required for the cast to the object type `dyn futures::future::Future<Item = std::option::Option<std::string::String>, Error = tiberius::Error> + std::marker::Send`

I create my connection per the below, then any query that I try to create, results in this error.

/// Create connection result, waiting for the future to complete
fn connect(
) -> Box<dyn Future<Item = SqlConnection<Box<dyn BoxableIo>>, Error = Error> + Send> {
    let conn_str = "server=tcp:localhost,1433;integratedSecurity=false;".to_owned();

    SqlConnection::connect(conn_str.as_str())
}

// This query won't compile,
pub fn run_query(
    value: String,
) -> Box<dyn Future<Item = Option<String>, Error = Error> + Send + 'static> {
    let fut = connect()
        .and_then(|conn| {
            conn.query(
                "INSERT INTO table (value) OUTPUT INSERTED.* values (@P1)",
                &[&value.as_str()],
            )
            .map(move |row: QueryRow| (row.get::<&str, &str>("value")).to_string())
            .collect()
            .map(move |(a, _)| a.get(0).map(|r| r.clone())) // get value, lose connection
        })
        .and_then(|result: Option<String>| Ok(result));
    Box::new(fut) // this fails to compile
}

Making it return impl Future<> instead of Box<dyn Future<> + Send> only pushes the error further down to the eventual consumer.

Do you know what I'm doing wrong? BoxableIo itself supports Send, so the issues seems to be with QueryStream. Thanks

[agalakhov]

This error is caused by line 73 of stmt.rs which includes PhantomData with a pointer. Replacing PhantomData<*const R> with PhantomData<R> resolves the issue.