pezkuwi-subxt/substrate/client/executor/wasmtime/src/state_holder.rs

// Copyright 2020 Parity Technologies (UK) Ltd.
// This file is part of Substrate.

// Substrate is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Substrate is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.

use crate::host::{HostContext, HostState};

scoped_tls::scoped_thread_local!(static HOST_STATE: HostState);

/// Provide `HostState` for the runtime method call and execute the given function `f`.
///
/// During the execution of the provided function `with_context` will be callable.
pub fn with_initialized_state<R, F>(s: &HostState, f: F) -> R
where
	F: FnOnce() -> R,
{
	HOST_STATE.set(s, f)
}

/// Create a `HostContext` from the contained `HostState` and execute the given function `f`.
///
/// This function is only callable within closure passed to `init_state`. Otherwise, the passed
/// context will be `None`.
pub fn with_context<R, F>(f: F) -> R
where
	F: FnOnce(Option<HostContext>) -> R,
{
	if !HOST_STATE.is_set() {
		return f(None)
	}
	HOST_STATE.with(|state| f(Some(state.materialize())))
}