Struct wasmtime_runtime::VMRuntimeLimits

#[repr(C)]
pub struct VMRuntimeLimits {
    pub stack_limit: UnsafeCell<usize>,
    pub fuel_consumed: UnsafeCell<i64>,
    pub epoch_deadline: UnsafeCell<u64>,
    pub last_wasm_exit_fp: UnsafeCell<usize>,
    pub last_wasm_exit_pc: UnsafeCell<usize>,
    pub last_wasm_entry_sp: UnsafeCell<usize>,
}

Structure used to control interrupting wasm code.

Fields

stack_limit: UnsafeCell<usize>

Current stack limit of the wasm module.

For more information see crates/cranelift/src/lib.rs.

fuel_consumed: UnsafeCell<i64>

Indicator of how much fuel has been consumed and is remaining to WebAssembly.

This field is typically negative and increments towards positive. Upon turning positive a wasm trap will be generated. This field is only modified if wasm is configured to consume fuel.

epoch_deadline: UnsafeCell<u64>

Deadline epoch for interruption: if epoch-based interruption is enabled and the global (per engine) epoch counter is observed to reach or exceed this value, the guest code will yield if running asynchronously.

last_wasm_exit_fp: UnsafeCell<usize>

The value of the frame pointer register when we last called from Wasm to the host.

Maintained by our Wasm-to-host trampoline, and cleared just before calling into Wasm in catch_traps.

This member is 0 when Wasm is actively running and has not called out to the host.

Used to find the start of a a contiguous sequence of Wasm frames when walking the stack.

last_wasm_exit_pc: UnsafeCell<usize>

The last Wasm program counter before we called from Wasm to the host.

Maintained by our Wasm-to-host trampoline, and cleared just before calling into Wasm in catch_traps.

This member is 0 when Wasm is actively running and has not called out to the host.

Used when walking a contiguous sequence of Wasm frames.

last_wasm_entry_sp: UnsafeCell<usize>

The last host stack pointer before we called into Wasm from the host.

Maintained by our host-to-Wasm trampoline, and cleared just before calling into Wasm in catch_traps.

This member is 0 when Wasm is actively running and has not called out to the host.

When a host function is wrapped into a wasmtime::Func, and is then called from the host, then this member has the sentinal value of -1 as usize, meaning that this contiguous sequence of Wasm frames is the empty sequence, and it is not safe to dereference the last_wasm_exit_fp.

Used to find the end of a contiguous sequence of Wasm frames when walking the stack.

Trait Implementations

impl Debug for VMRuntimeLimits

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for VMRuntimeLimits

fn default() -> VMRuntimeLimits

Returns the “default value” for a type.

impl Send for VMRuntimeLimits

impl Sync for VMRuntimeLimits