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/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
// SPDX-License-Identifier: MIT OR LGPL-2.0-or-later
// SPDX-FileCopyrightText: 2017 Endless Mobile, Inc.
// SPDX-FileCopyrightText: 2021 Canonical Ltd.
// SPDX-FileContributor: Authored by: Philip Chimento <philip@endlessm.com>
// SPDX-FileContributor: Philip Chimento <philip.chimento@gmail.com>
// SPDX-FileContributor: Marco Trevisan <marco.trevisan@canonical.com>
#include <algorithm> // for find_if
#include <atomic>
#include <deque>
#include <utility> // for pair
#include "gi/object.h"
#include "gi/toggle.h"
#include "util/log.h"
/* No-op unless GJS_VERBOSE_ENABLE_LIFECYCLE is defined to 1. */
inline void debug(const char* did GJS_USED_VERBOSE_LIFECYCLE,
const ObjectInstance* object GJS_USED_VERBOSE_LIFECYCLE) {
gjs_debug_lifecycle(GJS_DEBUG_GOBJECT, "ToggleQueue %s %p (%s @ %p)", did,
object, object ? g_type_name(object->gtype()) : "",
object ? object->ptr() : nullptr);
}
void ToggleQueue::lock() {
auto holding_thread = std::thread::id();
auto current_thread = std::this_thread::get_id();
while (!m_holder.compare_exchange_weak(holding_thread, current_thread,
std::memory_order_acquire)) {
// In case the current thread is holding the lock, we can just try
// again, checking if this is still true and in case continue
if (holding_thread != current_thread)
holding_thread = std::thread::id();
}
m_holder_ref_count++;
}
void ToggleQueue::maybe_unlock() {
g_assert(owns_lock() && "Nothing to unlock here");
if (!(--m_holder_ref_count))
m_holder.store(std::thread::id(), std::memory_order_release);
}
std::deque<ToggleQueue::Item>::iterator ToggleQueue::find_operation_locked(
const ObjectInstance* obj, ToggleQueue::Direction direction) {
return std::find_if(
q.begin(), q.end(), [obj, direction](const Item& item) -> bool {
return item.object == obj && item.direction == direction;
});
}
std::deque<ToggleQueue::Item>::const_iterator
ToggleQueue::find_operation_locked(const ObjectInstance* obj,
ToggleQueue::Direction direction) const {
return std::find_if(
q.begin(), q.end(), [obj, direction](const Item& item) -> bool {
return item.object == obj && item.direction == direction;
});
}
void ToggleQueue::handle_all_toggles(Handler handler) {
g_assert(owns_lock() && "Unsafe access to queue");
while (handle_toggle(handler))
;
}
gboolean
ToggleQueue::idle_handle_toggle(void *data)
{
auto self = Locked(static_cast<ToggleQueue*>(data));
self->handle_all_toggles(self->m_toggle_handler);
return G_SOURCE_REMOVE;
}
void
ToggleQueue::idle_destroy_notify(void *data)
{
auto self = Locked(static_cast<ToggleQueue*>(data));
self->m_idle_id = 0;
self->m_toggle_handler = nullptr;
}
std::pair<bool, bool> ToggleQueue::is_queued(ObjectInstance* obj) const {
g_assert(owns_lock() && "Unsafe access to queue");
bool has_toggle_down = find_operation_locked(obj, DOWN) != q.end();
bool has_toggle_up = find_operation_locked(obj, UP) != q.end();
return {has_toggle_down, has_toggle_up};
}
std::pair<bool, bool> ToggleQueue::cancel(ObjectInstance* obj) {
debug("cancel", obj);
g_assert(owns_lock() && "Unsafe access to queue");
bool had_toggle_down = false;
bool had_toggle_up = false;
for (auto it = q.begin(); it != q.end();) {
if (it->object == obj) {
had_toggle_down |= (it->direction == Direction::DOWN);
had_toggle_up |= (it->direction == Direction::UP);
it = q.erase(it);
continue;
}
it++;
}
gjs_debug_lifecycle(GJS_DEBUG_GOBJECT, "ToggleQueue: %p (%p) was %s", obj,
obj ? obj->ptr() : nullptr,
had_toggle_down && had_toggle_up
? "queued to toggle BOTH"
: had_toggle_down ? "queued to toggle DOWN"
: had_toggle_up ? "queued to toggle UP"
: "not queued");
return {had_toggle_down, had_toggle_up};
}
bool ToggleQueue::handle_toggle(Handler handler) {
g_assert(owns_lock() && "Unsafe access to queue");
if (q.empty())
return false;
auto const& item = q.front();
if (item.direction == UP)
debug("handle UP", item.object);
else
debug("handle DOWN", item.object);
handler(item.object, item.direction);
q.pop_front();
return true;
}
void
ToggleQueue::shutdown(void)
{
debug("shutdown", nullptr);
g_assert(((void)"Queue should have been emptied before shutting down",
q.empty()));
m_shutdown = true;
}
void ToggleQueue::enqueue(ObjectInstance* obj, ToggleQueue::Direction direction,
ToggleQueue::Handler handler) {
g_assert(owns_lock() && "Unsafe access to queue");
if (G_UNLIKELY (m_shutdown)) {
gjs_debug(GJS_DEBUG_GOBJECT,
"Enqueuing GObject %p to toggle %s after "
"shutdown, probably from another thread (%p).",
obj->ptr(), direction == UP ? "UP" : "DOWN", g_thread_self());
return;
}
auto other_item = find_operation_locked(obj, direction == UP ? DOWN : UP);
if (other_item != q.end()) {
if (direction == UP) {
debug("enqueue UP, dequeuing already DOWN object", obj);
} else {
debug("enqueue DOWN, dequeuing already UP object", obj);
}
q.erase(other_item);
return;
}
/* Only keep an unowned reference on the object here, as if we're here, the
* JSObject wrapper has already a reference and we don't want to cause
* any weak notify in case it has lost one already in the main thread.
* So let's just save the pointer to keep track of the object till we
* don't handle this toggle.
* We rely on object's cancelling the queue in case an object gets
* finalized earlier than we've processed it.
*/
q.emplace_back(obj, direction);
if (direction == UP) {
debug("enqueue UP", obj);
} else {
debug("enqueue DOWN", obj);
}
if (m_idle_id) {
g_assert(((void) "Should always enqueue with the same handler",
m_toggle_handler == handler));
return;
}
m_toggle_handler = handler;
m_idle_id = g_idle_add_full(G_PRIORITY_HIGH, idle_handle_toggle, this,
idle_destroy_notify);
}
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