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give sychronous ResourceLimiter an async alternative

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This commit is contained in:
Pat Hickey
2021-09-28 12:21:13 -07:00
parent e04357505e
commit 18a355e092
19 changed files with 373 additions and 236 deletions
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89
crates/runtime/src/instance.rs
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@@ -12,7 +12,6 @@ use crate::vmcontext::{
VMInterrupts, VMMemoryDefinition, VMMemoryImport, VMTableDefinition, VMTableImport,
};
use crate::{ExportFunction, ExportGlobal, ExportMemory, ExportTable, Store};
use anyhow::Error;
use memoffset::offset_of;
use more_asserts::assert_lt;
use std::alloc::Layout;
@@ -33,86 +32,6 @@ mod allocator;
pub use allocator::*;
/// Value returned by [`ResourceLimiter::instances`] default method
pub const DEFAULT_INSTANCE_LIMIT: usize = 10000;
/// Value returned by [`ResourceLimiter::tables`] default method
pub const DEFAULT_TABLE_LIMIT: usize = 10000;
/// Value returned by [`ResourceLimiter::memories`] default method
pub const DEFAULT_MEMORY_LIMIT: usize = 10000;
/// Used by hosts to limit resource consumption of instances.
///
/// An instance can be created with a resource limiter so that hosts can take into account
/// non-WebAssembly resource usage to determine if a linear memory or table should grow.
pub trait ResourceLimiter {
/// Notifies the resource limiter that an instance's linear memory has been
/// requested to grow.
///
/// * `current` is the current size of the linear memory in bytes.
/// * `desired` is the desired size of the linear memory in bytes.
/// * `maximum` is either the linear memory's maximum or a maximum from an
/// instance allocator, also in bytes. A value of `None`
/// indicates that the linear memory is unbounded.
///
/// This function should return `true` to indicate that the growing
/// operation is permitted or `false` if not permitted. Returning `true`
/// when a maximum has been exceeded will have no effect as the linear
/// memory will not grow.
///
/// This function is not guaranteed to be invoked for all requests to
/// `memory.grow`. Requests where the allocation requested size doesn't fit
/// in `usize` or exceeds the memory's listed maximum size may not invoke
/// this method.
fn memory_growing(&mut self, current: usize, desired: usize, maximum: Option<usize>) -> bool;
/// Notifies the resource limiter that growing a linear memory, permitted by
/// the `memory_growing` method, has failed.
///
/// Reasons for failure include: the growth exceeds the `maximum` passed to
/// `memory_growing`, or the operating system failed to allocate additional
/// memory. In that case, `error` might be downcastable to a `std::io::Error`.
fn memory_grow_failed(&mut self, _error: &Error) {}
/// Notifies the resource limiter that an instance's table has been requested to grow.
///
/// * `current` is the current number of elements in the table.
/// * `desired` is the desired number of elements in the table.
/// * `maximum` is either the table's maximum or a maximum from an instance allocator.
/// A value of `None` indicates that the table is unbounded.
///
/// This function should return `true` to indicate that the growing operation is permitted or
/// `false` if not permitted. Returning `true` when a maximum has been exceeded will have no
/// effect as the table will not grow.
fn table_growing(&mut self, current: u32, desired: u32, maximum: Option<u32>) -> bool;
/// The maximum number of instances that can be created for a `Store`.
///
/// Module instantiation will fail if this limit is exceeded.
///
/// This value defaults to 10,000.
fn instances(&self) -> usize {
DEFAULT_INSTANCE_LIMIT
}
/// The maximum number of tables that can be created for a `Store`.
///
/// Module instantiation will fail if this limit is exceeded.
///
/// This value defaults to 10,000.
fn tables(&self) -> usize {
DEFAULT_TABLE_LIMIT
}
/// The maximum number of linear memories that can be created for a `Store`
///
/// Instantiation will fail with an error if this limit is exceeded.
///
/// This value defaults to 10,000.
fn memories(&self) -> usize {
DEFAULT_MEMORY_LIMIT
}
}
/// A type that roughly corresponds to a WebAssembly instance, but is also used
/// for host-defined objects.
///
@@ -441,10 +360,10 @@ impl Instance {
(foreign_memory_index, foreign_instance)
}
};
let limiter = unsafe { (*instance.store()).limiter() };
let store = unsafe { &mut *instance.store() };
let memory = &mut instance.memories[idx];
let result = unsafe { memory.grow(delta, limiter) };
let result = unsafe { memory.grow(delta, store) };
let vmmemory = memory.vmmemory();
// Update the state used by wasm code in case the base pointer and/or
@@ -480,13 +399,13 @@ impl Instance {
delta: u32,
init_value: TableElement,
) -> Option<u32> {
let limiter = unsafe { (*self.store()).limiter() };
let store = unsafe { &mut *self.store() };
let table = self
.tables
.get_mut(table_index)
.unwrap_or_else(|| panic!("no table for index {}", table_index.index()));
let result = unsafe { table.grow(delta, init_value, limiter) };
let result = unsafe { table.grow(delta, init_value, store) };
// Keep the `VMContext` pointers used by compiled Wasm code up to
// date.