Module traphandlers 

WebAssembly trap handling, which is built on top of the lower-level signalhandling mechanisms.

Structs

StackCache 🔒

Per-thread cache holding a single ready-to-use coroutine stack. The hot path of on_wasm_stack pops from here without touching the global STACK_POOL’s atomics; only the first call on a thread or re-entrant nested calls fall back to the pool.

TrapHandlerContext 🔒

Read-only information that is used by signal handlers to handle and recover from traps.

TrapHandlerContextInner 🔒

VMConfig

Configuration for the runtime VM Currently only the stack size is configurable

Constants

MAX_STACK_SIZE

Maximum allowed default stack size (100 MiB) for the process-wide configuration set via set_stack_size.

TLS_STACK 🔒

TRAP_HANDLER 🔒

YIELDER 🔒

Statics

DEFAULT_STACK_SIZE 🔒

MAGIC 🔒

PREV_SIGBUS 🔒

PREV_SIGFPE 🔒

PREV_SIGILL 🔒

PREV_SIGSEGV 🔒

PREV_SIGUSR1 🔒

STACK_POOL 🔒

Pool of pre-allocated coroutine stacks to avoid repeated mmap syscalls. Acts as the cross-thread overflow store; per-thread reuse is served by TLS_STACK to keep the hot path atomic-free.

Traits

StackExt 🔒

Convenience extension for [Stack] that exposes the total mapped size.

Functions

acquire_stack 🔒

Acquire a coroutine stack large enough for min_size. Prefers the thread-local cache (no atomics), falls back to the global STACK_POOL, then allocates a fresh stack.

catch_traps^⚠

Catches any wasm traps that happen within the execution of closure, returning them as a Result.

drain_stack_pool

Drains the coroutine stack pool at the moment it runs.

get_pc_sp 🔒 ^⚠

get_stack_size

Returns the process-wide default stack size in bytes.

init_traps

This function is required to be called before any WebAssembly is entered. This will configure global state such as signal handlers to prepare the process to receive wasm traps.

lazy_per_thread_init

A module for registering a custom alternate signal stack (sigaltstack).

on_host_stack

When executing on the Wasm stack, temporarily switch back to the host stack to perform an operation that should not be constrained by the Wasm stack limits.

on_wasm_stack 🔒

Runs the given function on a separate stack so that its stack usage can be bounded. Stack overflows and other traps can be caught and execution returned to the root of the stack.

platform_init 🔒 ^⚠

process_illegal_op 🔒 ^⚠

raise_lib_trap^⚠

Raises a trap from inside library code immediately.

raise_user_trap^⚠

Raises a user-defined trap immediately.

release_stack 🔒

Release a coroutine stack. Prefers the thread-local slot if empty (no atomics); otherwise pushes to the global STACK_POOL so the stack is still reusable by other threads.

resume_panic^⚠

Carries a Rust panic across wasm code and resumes the panic on the other side.

set_stack_size

Sets the process-wide default stack size for new Wasmer coroutines. The value is clamped to [8 KiB, MAX_STACK_SIZE].

trap_handler 🔒 ^⚠

unwind_with 🔒 ^⚠

update_context 🔒 ^⚠

Type Aliases

TrapHandlerFn

Function which may handle custom signals while processing traps.