sc_executor_common/
wasm_runtime.rs

1// This file is part of Substrate.
2
3// Copyright (C) Parity Technologies (UK) Ltd.
4// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
5
6// This program is free software: you can redistribute it and/or modify
7// it under the terms of the GNU General Public License as published by
8// the Free Software Foundation, either version 3 of the License, or
9// (at your option) any later version.
10
11// This program is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14// GNU General Public License for more details.
15
16// You should have received a copy of the GNU General Public License
17// along with this program. If not, see <https://www.gnu.org/licenses/>.
18
19//! Definitions for a wasm runtime.
20
21use crate::error::Error;
22
23pub use sc_allocator::AllocationStats;
24
25/// Default heap allocation strategy.
26pub const DEFAULT_HEAP_ALLOC_STRATEGY: HeapAllocStrategy =
27	HeapAllocStrategy::Static { extra_pages: DEFAULT_HEAP_ALLOC_PAGES };
28
29/// Default heap allocation pages.
30pub const DEFAULT_HEAP_ALLOC_PAGES: u32 = 2048;
31
32/// A trait that defines an abstract WASM runtime module.
33///
34/// This can be implemented by an execution engine.
35pub trait WasmModule: Sync + Send {
36	/// Create a new instance with the given heap allocation strategy.
37	///
38	/// The `heap_alloc_strategy` determines the memory limits applied to this instance.
39	fn new_instance(
40		&self,
41		heap_alloc_strategy: HeapAllocStrategy,
42	) -> Result<Box<dyn WasmInstance>, Error>;
43}
44
45/// A trait that defines an abstract wasm module instance.
46///
47/// This can be implemented by an execution engine.
48pub trait WasmInstance: Send {
49	/// Call a method on this WASM instance.
50	///
51	/// Before execution, instance is reset.
52	///
53	/// Returns the encoded result on success.
54	fn call(&mut self, method: &str, data: &[u8]) -> Result<Vec<u8>, Error> {
55		self.call_with_allocation_stats(method, data).0
56	}
57
58	/// Call a method on this WASM instance.
59	///
60	/// Before execution, instance is reset.
61	///
62	/// Returns the encoded result on success.
63	fn call_with_allocation_stats(
64		&mut self,
65		method: &str,
66		data: &[u8],
67	) -> (Result<Vec<u8>, Error>, Option<AllocationStats>);
68
69	/// Call an exported method on this WASM instance.
70	///
71	/// Before execution, instance is reset.
72	///
73	/// Returns the encoded result on success.
74	fn call_export(&mut self, method: &str, data: &[u8]) -> Result<Vec<u8>, Error> {
75		self.call(method.into(), data)
76	}
77
78	/// Update the heap allocation strategy for subsequent calls.
79	///
80	/// This is used when an instance is reused from a pool but the caller needs
81	/// a different memory limit than what the instance was originally created with.
82	fn set_heap_alloc_strategy(&mut self, _heap_alloc_strategy: HeapAllocStrategy) {}
83}
84
85/// Defines the heap pages allocation strategy the wasm runtime should use.
86///
87/// A heap page is defined as 64KiB of memory.
88#[derive(Debug, Copy, Clone, PartialEq, Hash, Eq)]
89pub enum HeapAllocStrategy {
90	/// Allocate a static number of heap pages.
91	///
92	/// The total number of allocated heap pages is the initial number of heap pages requested by
93	/// the wasm file plus the `extra_pages`.
94	Static {
95		/// The number of pages that will be added on top of the initial heap pages requested by
96		/// the wasm file.
97		extra_pages: u32,
98	},
99	/// Allocate the initial heap pages as requested by the wasm file and then allow it to grow
100	/// dynamically.
101	Dynamic {
102		/// The absolute maximum size of the linear memory (in pages).
103		///
104		/// When `Some(_)` the linear memory will be allowed to grow up to this limit.
105		/// When `None` the linear memory will be allowed to grow up to the maximum limit supported
106		/// by WASM (4GB).
107		maximum_pages: Option<u32>,
108	},
109}
110
111impl HeapAllocStrategy {
112	/// Double this heap allocation strategy.
113	pub const fn double(self) -> Self {
114		match self {
115			Self::Static { extra_pages } => {
116				Self::Static { extra_pages: extra_pages.saturating_mul(2) }
117			},
118			Self::Dynamic { maximum_pages } => Self::Dynamic {
119				maximum_pages: match maximum_pages {
120					Some(p) => Some(p.saturating_mul(2)),
121					None => None,
122				},
123			},
124		}
125	}
126}
sc_executor_common/wasm_runtime.rs

sc_executor_common/
wasm_runtime.rs
