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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
/* clang-format off */
#include "preamble.h"
/* not in preamble because we specialize for reading-from a uint64_t var (as
used by `s_schedule_task_common`) */
ssize_t write(int fd, void *bytes, size_t nbytes)
_(requires valid_fd(fd))
_(requires nbytes == sizeof(uint64_t))
_(requires \thread_local((uint64_t *)bytes))
;
static void s_schedule_task_common(struct aws_event_loop *event_loop, struct aws_task *task, uint64_t run_at_nanos
_(ghost \claim(c_event_loop))
_(ghost \claim(c_mutex))
)
_(always c_event_loop, event_loop->\closed)
_(requires \wrapped(c_mutex) && \claims_object(c_mutex, &(epoll_loop_of(event_loop)->task_pre_queue_mutex)))
_(requires \thread_local(task))
_(requires \wrapped(task))
_(requires task->fn->\valid)
_(writes task)
_(updates &epoll_loop_of(event_loop)->scheduler)
{
_(assert \always_by_claim(c_event_loop, event_loop))
_(assert \active_claim(c_event_loop))
struct epoll_loop *epoll_loop = event_loop->impl_data;
_(assert \inv(epoll_loop))
_(assert epoll_loop->\closed)
_(assert epoll_loop->write_task_handle.\closed)
_(assert \inv(&epoll_loop->write_task_handle))
_(assert valid_fd(epoll_loop->write_task_handle.data.fd))
/* if event loop and the caller are the same thread, just schedule and be done with it. */
if (s_is_on_callers_thread(event_loop _(ghost c_event_loop))) {
AWS_LOGF_TRACE(
AWS_LS_IO_EVENT_LOOP,
"id=%p: scheduling task %p in-thread for timestamp %llu",
(void *)event_loop,
(void *)task,
(unsigned long long)run_at_nanos);
if (run_at_nanos == 0) {
/* zero denotes "now" task */
aws_task_scheduler_schedule_now(&epoll_loop->scheduler, task);
} else {
aws_task_scheduler_schedule_future(&epoll_loop->scheduler, task, run_at_nanos);
}
return;
}
AWS_LOGF_TRACE(
AWS_LS_IO_EVENT_LOOP,
"id=%p: Scheduling task %p cross-thread for timestamp %llu",
(void *)event_loop,
(void *)task,
(unsigned long long)run_at_nanos);
_(unwrap task)
task->timestamp = run_at_nanos;
_(wrap task)
aws_mutex_lock(&epoll_loop->task_pre_queue_mutex _(ghost c_mutex));
_(assert epoll_loop->task_pre_queue.\owner == \me)
uint64_t counter = 1;
bool is_first_task = aws_linked_list_empty(&epoll_loop->task_pre_queue);
aws_linked_list_push_back(&epoll_loop->task_pre_queue, &task->node _(ghost task));
/* if the list was not empty, we already have a pending read on the pipe/eventfd, no need to write again. */
if (is_first_task) {
AWS_LOGF_TRACE(AWS_LS_IO_EVENT_LOOP, "id=%p: Waking up event-loop thread", (void *)event_loop);
/* If the write fails because the buffer is full, we don't actually care because that means there's a pending
* read on the pipe/eventfd and thus the event loop will end up checking to see if something has been queued.*/
_(assert \active_claim(c_event_loop)) /*< implies write_task_handle.data.fd is a valid fd
==> event_loop->\closed
==> epoll_loop->\closed ==> \inv(epoll_loop)
==> epoll_loop->write_task_handle.\closed ==> \inv(&epoll_loop->write_task_handle) */
ssize_t do_not_care = write(_(by_claim c_event_loop) epoll_loop->write_task_handle.data.fd, (void *)&counter, sizeof(counter));
(void)do_not_care;
}
aws_mutex_unlock(&epoll_loop->task_pre_queue_mutex _(ghost c_mutex));
}
static void s_schedule_task_now(struct aws_event_loop *event_loop, struct aws_task *task
_(ghost \claim(c_event_loop))
_(ghost \claim(c_mutex))
) {
s_schedule_task_common(event_loop, task, 0 /* zero denotes "now" task */ _(ghost c_event_loop) _(ghost c_mutex));
}
static void s_schedule_task_future(struct aws_event_loop *event_loop, struct aws_task *task, uint64_t run_at_nanos
_(ghost \claim(c_event_loop))
_(ghost \claim(c_mutex))
) {
s_schedule_task_common(event_loop, task, run_at_nanos _(ghost c_event_loop) _(ghost c_mutex));
}
/* clang-format on */
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