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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
//! An implementation of Houdini worklets.
//!
//! The goal of this implementation is to maximize responsiveness of worklets,
//! and in particular to ensure that the thread performing worklet tasks
//! is never busy GCing or loading worklet code. We do this by providing a custom
//! thread pool implementation, which only performs GC or code loading on
//! a backup thread, not on the primary worklet thread.
use std::cell::OnceCell;
use std::cmp::max;
use std::collections::{hash_map, HashMap};
use std::rc::Rc;
use std::sync::atomic::{AtomicIsize, Ordering};
use std::sync::Arc;
use std::thread;
use crossbeam_channel::{unbounded, Receiver, Sender};
use dom_struct::dom_struct;
use js::jsapi::{GCReason, JSGCParamKey, JSTracer, JS_GetGCParameter, JS_GC};
use malloc_size_of::malloc_size_of_is_0;
use msg::constellation_msg::PipelineId;
use net_traits::request::{Destination, RequestBuilder, RequestMode};
use net_traits::IpcSend;
use servo_url::{ImmutableOrigin, ServoUrl};
use style::thread_state::{self, ThreadState};
use swapper::{swapper, Swapper};
use uuid::Uuid;
use crate::dom::bindings::codegen::Bindings::RequestBinding::RequestCredentials;
use crate::dom::bindings::codegen::Bindings::WindowBinding::Window_Binding::WindowMethods;
use crate::dom::bindings::codegen::Bindings::WorkletBinding::{WorkletMethods, WorkletOptions};
use crate::dom::bindings::error::Error;
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::refcounted::TrustedPromise;
use crate::dom::bindings::reflector::{reflect_dom_object, Reflector};
use crate::dom::bindings::root::{Dom, DomRoot, RootCollection, ThreadLocalStackRoots};
use crate::dom::bindings::str::USVString;
use crate::dom::bindings::trace::{CustomTraceable, JSTraceable, RootedTraceableBox};
use crate::dom::globalscope::GlobalScope;
use crate::dom::promise::Promise;
use crate::dom::testworkletglobalscope::TestWorkletTask;
use crate::dom::window::Window;
use crate::dom::workletglobalscope::{
WorkletGlobalScope, WorkletGlobalScopeInit, WorkletGlobalScopeType, WorkletTask,
};
use crate::fetch::load_whole_resource;
use crate::realms::InRealm;
use crate::script_runtime::{new_rt_and_cx, CommonScriptMsg, Runtime, ScriptThreadEventCategory};
use crate::script_thread::{MainThreadScriptMsg, ScriptThread};
use crate::task::TaskBox;
use crate::task_source::TaskSourceName;
// Magic numbers
const WORKLET_THREAD_POOL_SIZE: u32 = 3;
const MIN_GC_THRESHOLD: u32 = 1_000_000;
#[derive(JSTraceable, MallocSizeOf)]
struct DroppableField {
worklet_id: WorkletId,
/// The cached version of the script thread's WorkletThreadPool. We keep this cached
/// because we may need to access it after the script thread has terminated.
#[ignore_malloc_size_of = "Difficult to measure memory usage of Rc<...> types"]
thread_pool: OnceCell<Rc<WorkletThreadPool>>,
}
impl Drop for DroppableField {
fn drop(&mut self) {
let worklet_id = self.worklet_id;
if let Some(thread_pool) = self.thread_pool.get_mut() {
thread_pool.exit_worklet(worklet_id);
}
}
}
#[dom_struct]
/// <https://drafts.css-houdini.org/worklets/#worklet>
pub struct Worklet {
reflector: Reflector,
window: Dom<Window>,
global_type: WorkletGlobalScopeType,
droppable_field: DroppableField,
}
impl Worklet {
fn new_inherited(window: &Window, global_type: WorkletGlobalScopeType) -> Worklet {
Worklet {
reflector: Reflector::new(),
window: Dom::from_ref(window),
global_type,
droppable_field: DroppableField {
worklet_id: WorkletId::new(),
thread_pool: OnceCell::new(),
},
}
}
pub fn new(window: &Window, global_type: WorkletGlobalScopeType) -> DomRoot<Worklet> {
debug!("Creating worklet {:?}.", global_type);
reflect_dom_object(
Box::new(Worklet::new_inherited(window, global_type)),
window,
)
}
pub fn worklet_id(&self) -> WorkletId {
self.droppable_field.worklet_id
}
#[allow(dead_code)]
pub fn worklet_global_scope_type(&self) -> WorkletGlobalScopeType {
self.global_type
}
}
impl WorkletMethods for Worklet {
/// <https://drafts.css-houdini.org/worklets/#dom-worklet-addmodule>
fn AddModule(
&self,
module_url: USVString,
options: &WorkletOptions,
comp: InRealm,
) -> Rc<Promise> {
// Step 1.
let promise = Promise::new_in_current_realm(comp);
// Step 3.
let module_url_record = match self.window.Document().base_url().join(&module_url.0) {
Ok(url) => url,
Err(err) => {
// Step 4.
debug!("URL {:?} parse error {:?}.", module_url.0, err);
promise.reject_error(Error::Syntax);
return promise;
},
};
debug!("Adding Worklet module {}.", module_url_record);
// Steps 6-12 in parallel.
let pending_tasks_struct = PendingTasksStruct::new();
let global = self.window.upcast::<GlobalScope>();
self.droppable_field
.thread_pool
.get_or_init(ScriptThread::worklet_thread_pool)
.fetch_and_invoke_a_worklet_script(
global.pipeline_id(),
self.droppable_field.worklet_id,
self.global_type,
self.window.origin().immutable().clone(),
global.api_base_url(),
module_url_record,
options.credentials,
pending_tasks_struct,
&promise,
);
// Step 5.
debug!("Returning promise.");
promise
}
}
/// A guid for worklets.
#[derive(Clone, Copy, Debug, Eq, Hash, JSTraceable, PartialEq)]
pub struct WorkletId(#[no_trace] Uuid);
malloc_size_of_is_0!(WorkletId);
impl WorkletId {
fn new() -> WorkletId {
WorkletId(servo_rand::random_uuid())
}
}
/// <https://drafts.css-houdini.org/worklets/#pending-tasks-struct>
#[derive(Clone, Debug)]
struct PendingTasksStruct(Arc<AtomicIsize>);
impl PendingTasksStruct {
fn new() -> PendingTasksStruct {
PendingTasksStruct(Arc::new(AtomicIsize::new(
WORKLET_THREAD_POOL_SIZE as isize,
)))
}
fn set_counter_to(&self, value: isize) -> isize {
self.0.swap(value, Ordering::AcqRel)
}
fn decrement_counter_by(&self, offset: isize) -> isize {
self.0.fetch_sub(offset, Ordering::AcqRel)
}
}
/// Worklets execute in a dedicated thread pool.
///
/// The goal is to ensure that there is a primary worklet thread,
/// which is able to responsively execute worklet code. In particular,
/// worklet execution should not be delayed by GC, or by script
/// loading.
///
/// To achieve this, we implement a three-thread pool, with the
/// threads cycling between three thread roles:
///
/// * The primary worklet thread is the one available to execute
/// worklet code.
///
/// * The hot backup thread may peform GC, but otherwise is expected
/// to take over the primary role.
///
/// * The cold backup thread may peform script loading and other
/// long-running tasks.
///
/// In the implementation, we use two kinds of messages:
///
/// * Data messages are expected to be processed quickly, and include
/// the worklet tasks to be performed by the primary thread, as
/// well as requests to change role or quit execution.
///
/// * Control messages are expected to be processed more slowly, and
/// include script loading.
///
/// Data messages are targeted at a role, for example, task execution
/// is expected to be performed by whichever thread is currently
/// primary. Control messages are targeted at a thread, for example
/// adding a module is performed in every thread, even if they change roles
/// in the middle of module loading.
///
/// The thread pool lives in the script thread, and is initialized
/// when a worklet adds a module. It is dropped when the script thread
/// is dropped, and asks each of the worklet threads to quit.
///
/// Layout can end up blocking on the primary worklet thread
/// (e.g. when invoking a paint callback), so it is important to avoid
/// deadlock by making sure the primary worklet thread doesn't end up
/// blocking waiting on layout. In particular, since the constellation
/// can block waiting on layout, this means the primary worklet thread
/// can't block waiting on the constellation. In general, the primary
/// worklet thread shouldn't perform any blocking operations. If a worklet
/// thread needs to do anything blocking, it should send a control
/// message, to make sure that the blocking operation is performed
/// by a backup thread, not by the primary thread.
#[derive(Clone, JSTraceable)]
pub struct WorkletThreadPool {
// Channels to send data messages to the three roles.
#[no_trace]
primary_sender: Sender<WorkletData>,
#[no_trace]
hot_backup_sender: Sender<WorkletData>,
#[no_trace]
cold_backup_sender: Sender<WorkletData>,
// Channels to send control messages to the three threads.
#[no_trace]
control_sender_0: Sender<WorkletControl>,
#[no_trace]
control_sender_1: Sender<WorkletControl>,
#[no_trace]
control_sender_2: Sender<WorkletControl>,
}
impl Drop for WorkletThreadPool {
fn drop(&mut self) {
let _ = self.cold_backup_sender.send(WorkletData::Quit);
let _ = self.hot_backup_sender.send(WorkletData::Quit);
let _ = self.primary_sender.send(WorkletData::Quit);
}
}
impl WorkletThreadPool {
/// Create a new thread pool and spawn the threads.
/// When the thread pool is dropped, the threads will be asked to quit.
pub fn spawn(global_init: WorkletGlobalScopeInit) -> WorkletThreadPool {
let primary_role = WorkletThreadRole::new(false, false);
let hot_backup_role = WorkletThreadRole::new(true, false);
let cold_backup_role = WorkletThreadRole::new(false, true);
let primary_sender = primary_role.sender.clone();
let hot_backup_sender = hot_backup_role.sender.clone();
let cold_backup_sender = cold_backup_role.sender.clone();
let init = WorkletThreadInit {
primary_sender: primary_sender.clone(),
hot_backup_sender: hot_backup_sender.clone(),
cold_backup_sender: cold_backup_sender.clone(),
global_init,
};
WorkletThreadPool {
primary_sender,
hot_backup_sender,
cold_backup_sender,
control_sender_0: WorkletThread::spawn(primary_role, init.clone(), 0),
control_sender_1: WorkletThread::spawn(hot_backup_role, init.clone(), 1),
control_sender_2: WorkletThread::spawn(cold_backup_role, init, 2),
}
}
/// Loads a worklet module into every worklet thread.
/// If all of the threads load successfully, the promise is resolved.
/// If any of the threads fails to load, the promise is rejected.
/// <https://drafts.css-houdini.org/worklets/#fetch-and-invoke-a-worklet-script>
fn fetch_and_invoke_a_worklet_script(
&self,
pipeline_id: PipelineId,
worklet_id: WorkletId,
global_type: WorkletGlobalScopeType,
origin: ImmutableOrigin,
base_url: ServoUrl,
script_url: ServoUrl,
credentials: RequestCredentials,
pending_tasks_struct: PendingTasksStruct,
promise: &Rc<Promise>,
) {
// Send each thread a control message asking it to load the script.
for sender in &[
&self.control_sender_0,
&self.control_sender_1,
&self.control_sender_2,
] {
let _ = sender.send(WorkletControl::FetchAndInvokeAWorkletScript {
pipeline_id,
worklet_id,
global_type,
origin: origin.clone(),
base_url: base_url.clone(),
script_url: script_url.clone(),
credentials,
pending_tasks_struct: pending_tasks_struct.clone(),
promise: TrustedPromise::new(promise.clone()),
});
}
self.wake_threads();
}
pub(crate) fn exit_worklet(&self, worklet_id: WorkletId) {
for sender in &[
&self.control_sender_0,
&self.control_sender_1,
&self.control_sender_2,
] {
let _ = sender.send(WorkletControl::ExitWorklet(worklet_id));
}
self.wake_threads();
}
/// For testing.
pub fn test_worklet_lookup(&self, id: WorkletId, key: String) -> Option<String> {
let (sender, receiver) = unbounded();
let msg = WorkletData::Task(id, WorkletTask::Test(TestWorkletTask::Lookup(key, sender)));
let _ = self.primary_sender.send(msg);
receiver.recv().expect("Test worklet has died?")
}
fn wake_threads(&self) {
// If any of the threads are blocked waiting on data, wake them up.
let _ = self.cold_backup_sender.send(WorkletData::WakeUp);
let _ = self.hot_backup_sender.send(WorkletData::WakeUp);
let _ = self.primary_sender.send(WorkletData::WakeUp);
}
}
/// The data messages sent to worklet threads
enum WorkletData {
Task(WorkletId, WorkletTask),
StartSwapRoles(Sender<WorkletData>),
FinishSwapRoles(Swapper<WorkletThreadRole>),
WakeUp,
Quit,
}
/// The control message sent to worklet threads
enum WorkletControl {
ExitWorklet(WorkletId),
FetchAndInvokeAWorkletScript {
pipeline_id: PipelineId,
worklet_id: WorkletId,
global_type: WorkletGlobalScopeType,
origin: ImmutableOrigin,
base_url: ServoUrl,
script_url: ServoUrl,
credentials: RequestCredentials,
pending_tasks_struct: PendingTasksStruct,
promise: TrustedPromise,
},
}
/// A role that a worklet thread can be playing.
///
/// These roles are used as tokens or capabilities, we track unique
/// ownership using Rust's types, and use atomic swapping to exchange
/// them between worklet threads. This ensures that each thread pool has
/// exactly one primary, one hot backup and one cold backup.
struct WorkletThreadRole {
receiver: Receiver<WorkletData>,
sender: Sender<WorkletData>,
is_hot_backup: bool,
is_cold_backup: bool,
}
impl WorkletThreadRole {
fn new(is_hot_backup: bool, is_cold_backup: bool) -> WorkletThreadRole {
let (sender, receiver) = unbounded();
WorkletThreadRole {
sender,
receiver,
is_hot_backup,
is_cold_backup,
}
}
}
/// Data to initialize a worklet thread.
#[derive(Clone)]
struct WorkletThreadInit {
/// Senders
primary_sender: Sender<WorkletData>,
hot_backup_sender: Sender<WorkletData>,
cold_backup_sender: Sender<WorkletData>,
/// Data for initializing new worklet global scopes
global_init: WorkletGlobalScopeInit,
}
/// A thread for executing worklets.
#[crown::unrooted_must_root_lint::must_root]
struct WorkletThread {
/// Which role the thread is currently playing
role: WorkletThreadRole,
/// The thread's receiver for control messages
control_receiver: Receiver<WorkletControl>,
/// Senders
primary_sender: Sender<WorkletData>,
hot_backup_sender: Sender<WorkletData>,
cold_backup_sender: Sender<WorkletData>,
/// Data for initializing new worklet global scopes
global_init: WorkletGlobalScopeInit,
/// The global scopes created by this thread
global_scopes: HashMap<WorkletId, Dom<WorkletGlobalScope>>,
/// A one-place buffer for control messages
control_buffer: Option<WorkletControl>,
/// The JS runtime
runtime: Runtime,
should_gc: bool,
gc_threshold: u32,
}
#[allow(unsafe_code)]
unsafe impl JSTraceable for WorkletThread {
unsafe fn trace(&self, trc: *mut JSTracer) {
debug!("Tracing worklet thread.");
self.global_scopes.trace(trc);
}
}
impl WorkletThread {
/// Spawn a new worklet thread, returning the channel to send it control messages.
#[allow(unsafe_code)]
#[allow(crown::unrooted_must_root)]
fn spawn(
role: WorkletThreadRole,
init: WorkletThreadInit,
thread_index: u8,
) -> Sender<WorkletControl> {
let (control_sender, control_receiver) = unbounded();
let _ = thread::Builder::new()
.name(format!("Worklet#{thread_index}"))
.spawn(move || {
// TODO: add a new IN_WORKLET thread state?
// TODO: set interrupt handler?
// TODO: configure the JS runtime (e.g. discourage GC, encourage agressive JIT)
debug!("Initializing worklet thread.");
thread_state::initialize(ThreadState::SCRIPT | ThreadState::IN_WORKER);
let roots = RootCollection::new();
let _stack_roots = ThreadLocalStackRoots::new(&roots);
let mut thread = RootedTraceableBox::new(WorkletThread {
role,
control_receiver,
primary_sender: init.primary_sender,
hot_backup_sender: init.hot_backup_sender,
cold_backup_sender: init.cold_backup_sender,
global_init: init.global_init,
global_scopes: HashMap::new(),
control_buffer: None,
runtime: new_rt_and_cx(None),
should_gc: false,
gc_threshold: MIN_GC_THRESHOLD,
});
thread.run();
})
.expect("Couldn't start worklet thread");
control_sender
}
/// The main event loop for a worklet thread
fn run(&mut self) {
loop {
// The handler for data messages
let message = self.role.receiver.recv().unwrap();
match message {
// The whole point of this thread pool is to perform tasks!
WorkletData::Task(id, task) => {
self.perform_a_worklet_task(id, task);
},
// To start swapping roles, get ready to perform an atomic swap,
// and block waiting for the other end to finish it.
// NOTE: the cold backup can block on the primary or the hot backup;
// the hot backup can block on the primary;
// the primary can block on nothing;
// this total ordering on thread roles is what guarantees deadlock-freedom.
WorkletData::StartSwapRoles(sender) => {
let (our_swapper, their_swapper) = swapper();
match sender.send(WorkletData::FinishSwapRoles(their_swapper)) {
Ok(_) => {},
Err(_) => {
// This might happen if the script thread shuts down while
// waiting for the worklet to finish.
return;
},
};
let _ = our_swapper.swap(&mut self.role);
},
// To finish swapping roles, perform the atomic swap.
// The other end should have already started the swap, so this shouldn't block.
WorkletData::FinishSwapRoles(swapper) => {
let _ = swapper.swap(&mut self.role);
},
// Wake up! There may be control messages to process.
WorkletData::WakeUp => {},
// Quit!
WorkletData::Quit => {
return;
},
}
// Only process control messages if we're the cold backup,
// otherwise if there are outstanding control messages,
// try to become the cold backup.
if self.role.is_cold_backup {
if let Some(control) = self.control_buffer.take() {
self.process_control(control);
}
while let Ok(control) = self.control_receiver.try_recv() {
self.process_control(control);
}
self.gc();
} else if self.control_buffer.is_none() {
if let Ok(control) = self.control_receiver.try_recv() {
self.control_buffer = Some(control);
let msg = WorkletData::StartSwapRoles(self.role.sender.clone());
let _ = self.cold_backup_sender.send(msg);
}
}
// If we are tight on memory, and we're a backup then perform a gc.
// If we are tight on memory, and we're the primary then try to become the hot backup.
// Hopefully this happens soon!
if self.current_memory_usage() > self.gc_threshold {
if self.role.is_hot_backup || self.role.is_cold_backup {
self.should_gc = false;
self.gc();
} else if !self.should_gc {
self.should_gc = true;
let msg = WorkletData::StartSwapRoles(self.role.sender.clone());
let _ = self.hot_backup_sender.send(msg);
}
}
}
}
/// The current memory usage of the thread
#[allow(unsafe_code)]
fn current_memory_usage(&self) -> u32 {
unsafe { JS_GetGCParameter(self.runtime.cx(), JSGCParamKey::JSGC_BYTES) }
}
/// Perform a GC.
#[allow(unsafe_code)]
fn gc(&mut self) {
debug!(
"BEGIN GC (usage = {}, threshold = {}).",
self.current_memory_usage(),
self.gc_threshold
);
unsafe { JS_GC(self.runtime.cx(), GCReason::API) };
self.gc_threshold = max(MIN_GC_THRESHOLD, self.current_memory_usage() * 2);
debug!(
"END GC (usage = {}, threshold = {}).",
self.current_memory_usage(),
self.gc_threshold
);
}
/// Get the worklet global scope for a given worklet.
/// Creates the worklet global scope if it doesn't exist.
fn get_worklet_global_scope(
&mut self,
pipeline_id: PipelineId,
worklet_id: WorkletId,
global_type: WorkletGlobalScopeType,
base_url: ServoUrl,
) -> DomRoot<WorkletGlobalScope> {
match self.global_scopes.entry(worklet_id) {
hash_map::Entry::Occupied(entry) => DomRoot::from_ref(entry.get()),
hash_map::Entry::Vacant(entry) => {
debug!("Creating new worklet global scope.");
let executor = WorkletExecutor::new(worklet_id, self.primary_sender.clone());
let result = global_type.new(
&self.runtime,
pipeline_id,
base_url,
executor,
&self.global_init,
);
entry.insert(Dom::from_ref(&*result));
result
},
}
}
/// Fetch and invoke a worklet script.
/// <https://drafts.css-houdini.org/worklets/#fetch-and-invoke-a-worklet-script>
fn fetch_and_invoke_a_worklet_script(
&self,
global_scope: &WorkletGlobalScope,
pipeline_id: PipelineId,
origin: ImmutableOrigin,
script_url: ServoUrl,
credentials: RequestCredentials,
pending_tasks_struct: PendingTasksStruct,
promise: TrustedPromise,
) {
debug!("Fetching from {}.", script_url);
// Step 1.
// TODO: Settings object?
// Step 2.
// TODO: Fetch a module graph, not just a single script.
// TODO: Fetch the script asynchronously?
// TODO: Caching.
let resource_fetcher = self.global_init.resource_threads.sender();
let request = RequestBuilder::new(
script_url,
global_scope.upcast::<GlobalScope>().get_referrer(),
)
.destination(Destination::Script)
.mode(RequestMode::CorsMode)
.credentials_mode(credentials.into())
.origin(origin);
let script = load_whole_resource(
request,
&resource_fetcher,
global_scope.upcast::<GlobalScope>(),
)
.ok()
.and_then(|(_, bytes)| String::from_utf8(bytes).ok());
// Step 4.
// NOTE: the spec parses and executes the script in separate steps,
// but our JS API doesn't separate these, so we do the steps out of order.
// Also, the spec currently doesn't allow exceptions to be propagated
// to the main script thread.
// https://github.com/w3c/css-houdini-drafts/issues/407
let ok = script
.map(|script| global_scope.evaluate_js(&script))
.unwrap_or(false);
if !ok {
// Step 3.
debug!("Failed to load script.");
let old_counter = pending_tasks_struct.set_counter_to(-1);
if old_counter > 0 {
self.run_in_script_thread(promise.reject_task(Error::Abort));
}
} else {
// Step 5.
debug!("Finished adding script.");
let old_counter = pending_tasks_struct.decrement_counter_by(1);
if old_counter == 1 {
debug!("Resolving promise.");
let msg = MainThreadScriptMsg::WorkletLoaded(pipeline_id);
self.global_init
.to_script_thread_sender
.send(msg)
.expect("Worklet thread outlived script thread.");
self.run_in_script_thread(promise.resolve_task(()));
}
}
}
/// Perform a task.
fn perform_a_worklet_task(&self, worklet_id: WorkletId, task: WorkletTask) {
match self.global_scopes.get(&worklet_id) {
Some(global) => global.perform_a_worklet_task(task),
None => warn!("No such worklet as {:?}.", worklet_id),
}
}
/// Process a control message.
fn process_control(&mut self, control: WorkletControl) {
match control {
WorkletControl::ExitWorklet(worklet_id) => {
self.global_scopes.remove(&worklet_id);
},
WorkletControl::FetchAndInvokeAWorkletScript {
pipeline_id,
worklet_id,
global_type,
origin,
base_url,
script_url,
credentials,
pending_tasks_struct,
promise,
} => {
let global =
self.get_worklet_global_scope(pipeline_id, worklet_id, global_type, base_url);
self.fetch_and_invoke_a_worklet_script(
&global,
pipeline_id,
origin,
script_url,
credentials,
pending_tasks_struct,
promise,
)
},
}
}
/// Run a task in the main script thread.
fn run_in_script_thread<T>(&self, task: T)
where
T: TaskBox + 'static,
{
// NOTE: It's unclear which task source should be used here:
// https://drafts.css-houdini.org/worklets/#dom-worklet-addmodule
let msg = CommonScriptMsg::Task(
ScriptThreadEventCategory::WorkletEvent,
Box::new(task),
None,
TaskSourceName::DOMManipulation,
);
let msg = MainThreadScriptMsg::Common(msg);
self.global_init
.to_script_thread_sender
.send(msg)
.expect("Worklet thread outlived script thread.");
}
}
/// An executor of worklet tasks
#[derive(Clone, JSTraceable, MallocSizeOf)]
pub struct WorkletExecutor {
worklet_id: WorkletId,
#[ignore_malloc_size_of = "channels are hard"]
#[no_trace]
primary_sender: Sender<WorkletData>,
}
impl WorkletExecutor {
fn new(worklet_id: WorkletId, primary_sender: Sender<WorkletData>) -> WorkletExecutor {
WorkletExecutor {
worklet_id,
primary_sender,
}
}
/// Schedule a worklet task to be peformed by the worklet thread pool.
pub fn schedule_a_worklet_task(&self, task: WorkletTask) {
let _ = self
.primary_sender
.send(WorkletData::Task(self.worklet_id, task));
}
}