//
// Cforall Version 1.0.0 Copyright (C) 2020 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// io.cfa --
//
// Author           : Thierry Delisle
// Created On       : Thu Apr 23 17:31:00 2020
// Last Modified By :
// Last Modified On :
// Update Count     :
//

#define __cforall_thread__
#define _GNU_SOURCE

#if defined(__CFA_DEBUG__)
	// #define __CFA_DEBUG_PRINT_IO__
	// #define __CFA_DEBUG_PRINT_IO_CORE__
#endif


#if defined(CFA_HAVE_LINUX_IO_URING_H)
	#include <errno.h>
	#include <signal.h>
	#include <stdint.h>
	#include <string.h>
	#include <unistd.h>

	extern "C" {
		#include <sys/syscall.h>
		#include <sys/eventfd.h>
		#include <sys/uio.h>

		#include <linux/io_uring.h>
	}

	#include "stats.hfa"
	#include "kernel.hfa"
	#include "kernel/fwd.hfa"
	#include "kernel/private.hfa"
	#include "kernel/cluster.hfa"
	#include "io/types.hfa"

	__attribute__((unused)) static const char * opcodes[] = {
		"OP_NOP",
		"OP_READV",
		"OP_WRITEV",
		"OP_FSYNC",
		"OP_READ_FIXED",
		"OP_WRITE_FIXED",
		"OP_POLL_ADD",
		"OP_POLL_REMOVE",
		"OP_SYNC_FILE_RANGE",
		"OP_SENDMSG",
		"OP_RECVMSG",
		"OP_TIMEOUT",
		"OP_TIMEOUT_REMOVE",
		"OP_ACCEPT",
		"OP_ASYNC_CANCEL",
		"OP_LINK_TIMEOUT",
		"OP_CONNECT",
		"OP_FALLOCATE",
		"OP_OPENAT",
		"OP_CLOSE",
		"OP_FILES_UPDATE",
		"OP_STATX",
		"OP_READ",
		"OP_WRITE",
		"OP_FADVISE",
		"OP_MADVISE",
		"OP_SEND",
		"OP_RECV",
		"OP_OPENAT2",
		"OP_EPOLL_CTL",
		"OP_SPLICE",
		"OP_PROVIDE_BUFFERS",
		"OP_REMOVE_BUFFERS",
		"OP_TEE",
		"INVALID_OP"
	};

	static io_context$ * __ioarbiter_allocate( io_arbiter$ & this, __u32 idxs[], __u32 want );
	static void __ioarbiter_submit( io_context$ * , __u32 idxs[], __u32 have, bool lazy );
	static void __ioarbiter_flush ( io_context$ & );
	static inline void __ioarbiter_notify( io_context$ & ctx );
//=============================================================================================
// I/O Polling
//=============================================================================================
	static inline unsigned __flush( struct io_context$ & );
	static inline __u32 __release_sqes( struct io_context$ & );
	extern void __kernel_unpark( thread$ * thrd, unpark_hint );

	static void ioring_syscsll( struct io_context$ & ctx, unsigned int min_comp, unsigned int flags ) {
		__STATS__( true, io.calls.flush++; )
		int ret;
		for() {
			ret = syscall( __NR_io_uring_enter, ctx.fd, ctx.sq.to_submit, min_comp, flags, (sigset_t *)0p, _NSIG / 8);
			if( ret < 0 ) {
				switch((int)errno) {
				case EINTR:
					continue;
				case EAGAIN:
				case EBUSY:
					// Update statistics
					__STATS__( false, io.calls.errors.busy ++; )
					return false;
				default:
					abort( "KERNEL ERROR: IO_URING SYSCALL - (%d) %s\n", (int)errno, strerror(errno) );
				}
			}
			break;
		}

		__cfadbg_print_safe(io, "Kernel I/O : %u submitted to io_uring %d\n", ret, ctx.fd);
		__STATS__( true, io.calls.submitted += ret; )
		/* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );
		/* paranoid */ verify( ctx.sq.to_submit >= ret );

		ctx.sq.to_submit -= ret;

		/* paranoid */ verify( ctx.sq.to_submit <= *ctx.sq.num );

		// Release the consumed SQEs
		__release_sqes( ctx );

		/* paranoid */ verify( ! __preemption_enabled() );

		__atomic_store_n(&ctx.proc->io.pending, false, __ATOMIC_RELAXED);
	}

	static bool try_acquire( io_context$ * ctx ) __attribute__((nonnull(1))) {
		/* paranoid */ verify( ! __preemption_enabled() );
		/* paranoid */ verify( ready_schedule_islocked() );


		{
			const __u32 head = *ctx->cq.head;
			const __u32 tail = *ctx->cq.tail;

			if(head == tail) return false;
		}

		// Drain the queue
		if(!__atomic_try_acquire(&ctx->cq.lock)) {
			__STATS__( false, io.calls.locked++; )
			return false;
		}

		return true;
	}

	static bool __cfa_do_drain( io_context$ * ctx, cluster * cltr ) __attribute__((nonnull(1, 2))) {
		/* paranoid */ verify( ! __preemption_enabled() );
		/* paranoid */ verify( ready_schedule_islocked() );
		/* paranoid */ verify( ctx->cq.lock == true );

		const __u32 mask = *ctx->cq.mask;
		const __u32 num  = *ctx->cq.num;
		unsigned long long ts_prev = ctx->cq.ts;
		unsigned long long ts_next;

		// We might need to do this multiple times if more events completed than can fit in the queue.
		for() {
			// re-read the head and tail in case it already changed.
			const __u32 head = *ctx->cq.head;
			const __u32 tail = *ctx->cq.tail;
			const __u32 count = tail - head;
			__STATS__( false, io.calls.drain++; io.calls.completed += count; )

			for(i; count) {
				unsigned idx = (head + i) & mask;
				volatile struct io_uring_cqe & cqe = ctx->cq.cqes[idx];

				/* paranoid */ verify(&cqe);

				struct io_future_t * future = (struct io_future_t *)(uintptr_t)cqe.user_data;
				// __cfadbg_print_safe( io, "Kernel I/O : Syscall completed : cqe %p, result %d for %p\n", &cqe, cqe.res, future );

				__kernel_unpark( fulfil( *future, cqe.res, false ), UNPARK_LOCAL );
			}

			ts_next = ctx->cq.ts = rdtscl();

			// Mark to the kernel that the cqe has been seen
			// Ensure that the kernel only sees the new value of the head index after the CQEs have been read.
			__atomic_store_n( ctx->cq.head, head + count, __ATOMIC_SEQ_CST );
			ctx->proc->idle_wctx.drain_time = ts_next;

			if(likely(count < num)) break;

			ioring_syscsll( *ctx, 0, IORING_ENTER_GETEVENTS);
		}

		__cfadbg_print_safe(io, "Kernel I/O : %u completed age %llu\n", count, ts_next);
		/* paranoid */ verify( ready_schedule_islocked() );
		/* paranoid */ verify( ! __preemption_enabled() );

		__atomic_unlock(&ctx->cq.lock);

		touch_tsc( cltr->sched.io.tscs, ctx->cq.id, ts_prev, ts_next, false );

		return true;
	}

	bool __cfa_io_drain( struct processor * proc ) {
		bool local = false;
		bool remote = false;

		ready_schedule_lock();

		cluster * const cltr = proc->cltr;
		io_context$ * const ctx = proc->io.ctx;
		/* paranoid */ verify( cltr );
		/* paranoid */ verify( ctx );

		with(cltr->sched) {
			const size_t ctxs_count = io.count;

			/* paranoid */ verify( ready_schedule_islocked() );
			/* paranoid */ verify( ! __preemption_enabled() );
			/* paranoid */ verify( active_processor() == proc );
			/* paranoid */ verify( __shard_factor.io > 0 );
			/* paranoid */ verify( ctxs_count > 0 );
			/* paranoid */ verify( ctx->cq.id < ctxs_count );

			const unsigned this_cache = cache_id(cltr, ctx->cq.id / __shard_factor.io);
			const unsigned long long ctsc = rdtscl();

			if(proc->io.target == UINT_MAX) {
				uint64_t chaos = __tls_rand();
				unsigned ext = chaos & 0xff;
				unsigned other  = (chaos >> 8) % (ctxs_count);

				if(ext < 3 || __atomic_load_n(&caches[other / __shard_factor.io].id, __ATOMIC_RELAXED) == this_cache) {
					proc->io.target = other;
				}
			}
			else {
				const unsigned target = proc->io.target;
				/* paranoid */ verify( io.tscs[target].t.tv != ULLONG_MAX );
				HELP: if(target < ctxs_count) {
					const unsigned long long cutoff = calc_cutoff(ctsc, ctx->cq.id, ctxs_count, io.data, io.tscs, __shard_factor.io, false);
					const unsigned long long age = moving_average(ctsc, io.tscs[target].t.tv, io.tscs[target].t.ma, false);
					__cfadbg_print_safe(io, "Kernel I/O: Help attempt on %u from %u, age %'llu vs cutoff %'llu, %s\n", target, ctx->cq.id, age, cutoff, age > cutoff ? "yes" : "no");
					if(age <= cutoff) break HELP;

					if(!try_acquire(io.data[target])) break HELP;

					if(!__cfa_do_drain( io.data[target], cltr )) break HELP;

					remote = true;
					__STATS__( true, io.calls.helped++; )
				}
				proc->io.target = UINT_MAX;
			}
		}


		// Drain the local queue
		if(try_acquire( proc->io.ctx )) {
			local = __cfa_do_drain( proc->io.ctx, cltr );
		}

		/* paranoid */ verify( ready_schedule_islocked() );
		/* paranoid */ verify( ! __preemption_enabled() );
		/* paranoid */ verify( active_processor() == proc );

		ready_schedule_unlock();
		return local || remote;
	}

	bool __cfa_io_flush( struct processor * proc ) {
		/* paranoid */ verify( ! __preemption_enabled() );
		/* paranoid */ verify( proc );
		/* paranoid */ verify( proc->io.ctx );

		io_context$ & ctx = *proc->io.ctx;

		__ioarbiter_flush( ctx );

		if(ctx.sq.to_submit != 0) {
			ioring_syscsll(ctx, 0, 0);

		}

		return __cfa_io_drain( proc );
	}

//=============================================================================================
// I/O Submissions
//=============================================================================================

// Submition steps :
// 1 - Allocate a queue entry. The ring already has memory for all entries but only the ones
//     listed in sq.array are visible by the kernel. For those not listed, the kernel does not
//     offer any assurance that an entry is not being filled by multiple flags. Therefore, we
//     need to write an allocator that allows allocating concurrently.
//
// 2 - Actually fill the submit entry, this is the only simple and straightforward step.
//
// 3 - Append the entry index to the array and adjust the tail accordingly. This operation
//     needs to arrive to two concensus at the same time:
//     A - The order in which entries are listed in the array: no two threads must pick the
//         same index for their entries
//     B - When can the tail be update for the kernel. EVERY entries in the array between
//         head and tail must be fully filled and shouldn't ever be touched again.
//
	//=============================================================================================
	// Allocation
	// for user's convenience fill the sqes from the indexes
	static inline void __fill(struct io_uring_sqe * out_sqes[], __u32 want, __u32 idxs[], struct io_context$ * ctx)  {
		struct io_uring_sqe * sqes = ctx->sq.sqes;
		for(i; want) {
			// __cfadbg_print_safe(io, "Kernel I/O : filling loop\n");
			out_sqes[i] = &sqes[idxs[i]];
		}
	}

	// Try to directly allocate from the a given context
	// Not thread-safe
	static inline bool __alloc(struct io_context$ * ctx, __u32 idxs[], __u32 want) {
		__sub_ring_t & sq = ctx->sq;
		const __u32 mask  = *sq.mask;
		__u32 fhead = sq.free_ring.head;    // get the current head of the queue
		__u32 ftail = sq.free_ring.tail;    // get the current tail of the queue

		// If we don't have enough sqes, fail
		if((ftail - fhead) < want) { return false; }

		// copy all the indexes we want from the available list
		for(i; want) {
			// __cfadbg_print_safe(io, "Kernel I/O : allocating loop\n");
			idxs[i] = sq.free_ring.array[(fhead + i) & mask];
		}

		// Advance the head to mark the indexes as consumed
		__atomic_store_n(&sq.free_ring.head, fhead + want, __ATOMIC_RELEASE);

		// return success
		return true;
	}

	// Allocate an submit queue entry.
	// The kernel cannot see these entries until they are submitted, but other threads must be
	// able to see which entries can be used and which are already un used by an other thread
	// for convenience, return both the index and the pointer to the sqe
	// sqe == &sqes[idx]
	struct io_context$ * cfa_io_allocate(struct io_uring_sqe * sqes[], __u32 idxs[], __u32 want) libcfa_public {
		// __cfadbg_print_safe(io, "Kernel I/O : attempting to allocate %u\n", want);

		disable_interrupts();
		struct processor * proc = __cfaabi_tls.this_processor;
		io_context$ * ctx = proc->io.ctx;
		/* paranoid */ verify( __cfaabi_tls.this_processor );
		/* paranoid */ verify( ctx );

		// __cfadbg_print_safe(io, "Kernel I/O : attempting to fast allocation\n");

		// We can proceed to the fast path
		if( __alloc(ctx, idxs, want) ) {
			// Allocation was successful
			__STATS__( true, io.alloc.fast += 1; )
			enable_interrupts();

			// __cfadbg_print_safe(io, "Kernel I/O : fast allocation successful from ring %d\n", ctx->fd);

			__fill( sqes, want, idxs, ctx );
			return ctx;
		}
		// The fast path failed, fallback
		__STATS__( true, io.alloc.fail += 1; )

		// Fast path failed, fallback on arbitration
		__STATS__( true, io.alloc.slow += 1; )
		enable_interrupts();

		io_arbiter$ * ioarb = proc->cltr->io.arbiter;
		/* paranoid */ verify( ioarb );

		// __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for allocation\n");

		struct io_context$ * ret = __ioarbiter_allocate(*ioarb, idxs, want);

		// __cfadbg_print_safe(io, "Kernel I/O : slow allocation completed from ring %d\n", ret->fd);

		__fill( sqes, want, idxs,ret );
		return ret;
	}

	//=============================================================================================
	// submission
	static inline void __submit_only( struct io_context$ * ctx, __u32 idxs[], __u32 have) {
		// We can proceed to the fast path
		// Get the right objects
		__sub_ring_t & sq = ctx->sq;
		const __u32 mask  = *sq.mask;
		__u32 tail = *sq.kring.tail;

		// Add the sqes to the array
		for( i; have ) {
			// __cfadbg_print_safe(io, "Kernel I/O : __submit loop\n");
			sq.kring.array[ (tail + i) & mask ] = idxs[i];
		}

		// Make the sqes visible to the submitter
		__atomic_store_n(sq.kring.tail, tail + have, __ATOMIC_RELEASE);
		sq.to_submit += have;

		__atomic_store_n(&ctx->proc->io.pending, true, __ATOMIC_RELAXED);
		__atomic_store_n(&ctx->proc->io.dirty  , true, __ATOMIC_RELAXED);
	}

	static inline void __submit( struct io_context$ * ctx, __u32 idxs[], __u32 have, bool lazy) {
		__sub_ring_t & sq = ctx->sq;
		__submit_only(ctx, idxs, have);

		if(sq.to_submit > 30) {
			__tls_stats()->io.flush.full++;
			__cfa_io_flush( ctx->proc );
		}
		if(!lazy) {
			__tls_stats()->io.flush.eager++;
			__cfa_io_flush( ctx->proc );
		}
	}

	void cfa_io_submit( struct io_context$ * inctx, __u32 idxs[], __u32 have, bool lazy ) __attribute__((nonnull (1))) libcfa_public {
		// __cfadbg_print_safe(io, "Kernel I/O : attempting to submit %u (%s)\n", have, lazy ? "lazy" : "eager");

		disable_interrupts();
		__STATS__( true, if(!lazy) io.submit.eagr += 1; )
		struct processor * proc = __cfaabi_tls.this_processor;
		io_context$ * ctx = proc->io.ctx;
		/* paranoid */ verify( __cfaabi_tls.this_processor );
		/* paranoid */ verify( ctx );

		// Can we proceed to the fast path
		if( ctx == inctx )		// We have the right instance?
		{
			__submit(ctx, idxs, have, lazy);

			// Mark the instance as no longer in-use, re-enable interrupts and return
			__STATS__( true, io.submit.fast += 1; )
			enable_interrupts();

			// __cfadbg_print_safe(io, "Kernel I/O : submitted on fast path\n");
			return;
		}

		// Fast path failed, fallback on arbitration
		__STATS__( true, io.submit.slow += 1; )
		enable_interrupts();

		// __cfadbg_print_safe(io, "Kernel I/O : falling back on arbiter for submission\n");

		__ioarbiter_submit(inctx, idxs, have, lazy);
	}

	//=============================================================================================
	// Flushing
	// Go through the ring's submit queue and release everything that has already been consumed
	// by io_uring
	// This cannot be done by multiple threads
	static __u32 __release_sqes( struct io_context$ & ctx ) {
		const __u32 mask = *ctx.sq.mask;

		__attribute__((unused))
		__u32 ctail = *ctx.sq.kring.tail;    // get the current tail of the queue
		__u32 chead = *ctx.sq.kring.head;	 // get the current head of the queue
		__u32 phead = ctx.sq.kring.released; // get the head the last time we were here

		__u32 ftail = ctx.sq.free_ring.tail;  // get the current tail of the queue

		// the 3 fields are organized like this diagram
		// except it's are ring
		// ---+--------+--------+----
		// ---+--------+--------+----
		//    ^        ^        ^
		// phead    chead    ctail

		// make sure ctail doesn't wrap around and reach phead
		/* paranoid */ verify(
			   (ctail >= chead && chead >= phead)
			|| (chead >= phead && phead >= ctail)
			|| (phead >= ctail && ctail >= chead)
		);

		// find the range we need to clear
		__u32 count = chead - phead;

		if(count == 0) {
			return 0;
		}

		// We acquired an previous-head/current-head range
		// go through the range and release the sqes
		for( i; count ) {
			// __cfadbg_print_safe(io, "Kernel I/O : release loop\n");
			__u32 idx = ctx.sq.kring.array[ (phead + i) & mask ];
			ctx.sq.free_ring.array[ (ftail + i) & mask ] = idx;
		}

		ctx.sq.kring.released = chead;		// note up to were we processed
		__atomic_store_n(&ctx.sq.free_ring.tail, ftail + count, __ATOMIC_SEQ_CST);

		__ioarbiter_notify(ctx);

		return count;
	}

//=============================================================================================
// I/O Arbiter
//=============================================================================================
	static inline bool enqueue(__outstanding_io_queue & queue, __outstanding_io & item) {
		bool was_empty;

		// Lock the list, it's not thread safe
		lock( queue.lock __cfaabi_dbg_ctx2 );
		{
			was_empty = empty(queue.queue);

			// Add our request to the list
			add( queue.queue, item );

			// Mark as pending
			__atomic_store_n( &queue.empty, false, __ATOMIC_SEQ_CST );
		}
		unlock( queue.lock );

		return was_empty;
	}

	static inline bool empty(__outstanding_io_queue & queue ) {
		return __atomic_load_n( &queue.empty, __ATOMIC_SEQ_CST);
	}

	static io_context$ * __ioarbiter_allocate( io_arbiter$ & this, __u32 idxs[], __u32 want ) {
		// __cfadbg_print_safe(io, "Kernel I/O : arbiter allocating\n");

		__STATS__( false, io.alloc.block += 1; )

		// No one has any resources left, wait for something to finish
		// We need to add ourself to a list of pending allocs and wait for an answer
		__pending_alloc pa;
		pa.idxs = idxs;
		pa.want = want;

		enqueue(this.pending, (__outstanding_io&)pa);

		wait( pa.sem );

		return pa.ctx;

	}

	static void __ioarbiter_notify( io_arbiter$ & this, io_context$ * ctx ) {
		/* paranoid */ verify( !empty(this.pending.queue) );

		lock( this.pending.lock __cfaabi_dbg_ctx2 );
		{
			while( !empty(this.pending.queue) ) {
				__cfadbg_print_safe(io, "Kernel I/O : notifying\n");
				__u32 have = ctx->sq.free_ring.tail - ctx->sq.free_ring.head;
				__pending_alloc & pa = (__pending_alloc&)head( this.pending.queue );

				if( have > pa.want ) goto DONE;
				drop( this.pending.queue );

				/* paranoid */__attribute__((unused)) bool ret =

				__alloc(ctx, pa.idxs, pa.want);

				/* paranoid */ verify( ret );

				pa.ctx = ctx;

				post( pa.sem );
			}

			this.pending.empty = true;
			DONE:;
		}
		unlock( this.pending.lock );
	}

	static void __ioarbiter_notify( io_context$ & ctx ) {
		if(!empty( ctx.arbiter->pending )) {
			__ioarbiter_notify( *ctx.arbiter, &ctx );
		}
	}

	// Simply append to the pending
	static void __ioarbiter_submit( io_context$ * ctx, __u32 idxs[], __u32 have, bool lazy ) {
		__cfadbg_print_safe(io, "Kernel I/O : submitting %u from the arbiter to context %u\n", have, ctx->fd);

		__cfadbg_print_safe(io, "Kernel I/O : waiting to submit %u\n", have);

		__external_io ei;
		ei.idxs = idxs;
		ei.have = have;
		ei.lazy = lazy;

		bool we = enqueue(ctx->ext_sq, (__outstanding_io&)ei);

		__atomic_store_n(&ctx->proc->io.pending, true, __ATOMIC_SEQ_CST);

		if( we ) {
			sigval_t value = { PREEMPT_IO };
			pthread_sigqueue(ctx->proc->kernel_thread, SIGUSR1, value);
		}

		wait( ei.sem );

		__cfadbg_print_safe(io, "Kernel I/O : %u submitted from arbiter\n", have);
	}

	static void __ioarbiter_flush( io_context$ & ctx ) {
		if(!empty( ctx.ext_sq )) {
			__STATS__( false, io.flush.external += 1; )

			__cfadbg_print_safe(io, "Kernel I/O : arbiter flushing\n");

			lock( ctx.ext_sq.lock __cfaabi_dbg_ctx2 );
			{
				while( !empty(ctx.ext_sq.queue) ) {
					__external_io & ei = (__external_io&)drop( ctx.ext_sq.queue );

					__submit_only(&ctx, ei.idxs, ei.have);

					post( ei.sem );
				}

				ctx.ext_sq.empty = true;
			}
			unlock(ctx.ext_sq.lock );
		}
	}

	#if defined(CFA_WITH_IO_URING_IDLE)
		bool __kernel_read(struct processor * proc, io_future_t & future, iovec & iov, int fd) {
			io_context$ * ctx = proc->io.ctx;
			/* paranoid */ verify( ! __preemption_enabled() );
			/* paranoid */ verify( proc == __cfaabi_tls.this_processor );
			/* paranoid */ verify( ctx );

			__u32 idx;
			struct io_uring_sqe * sqe;

			// We can proceed to the fast path
			if( !__alloc(ctx, &idx, 1) ) {
				/* paranoid */ verify( false ); // for now check if this happens, next time just abort the sleep.
				return false;
			}

			// Allocation was successful
			__fill( &sqe, 1, &idx, ctx );

			sqe->user_data = (uintptr_t)&future;
			sqe->flags = 0;
			sqe->fd = fd;
			sqe->off = 0;
			sqe->ioprio = 0;
			sqe->fsync_flags = 0;
			sqe->__pad2[0] = 0;
			sqe->__pad2[1] = 0;
			sqe->__pad2[2] = 0;

			#if defined(CFA_HAVE_IORING_OP_READ)
				sqe->opcode = IORING_OP_READ;
				sqe->addr = (uint64_t)iov.iov_base;
				sqe->len = iov.iov_len;
			#elif defined(CFA_HAVE_READV) && defined(CFA_HAVE_IORING_OP_READV)
				sqe->opcode = IORING_OP_READV;
				sqe->addr = (uintptr_t)&iov;
				sqe->len = 1;
			#else
				#error CFA_WITH_IO_URING_IDLE but none of CFA_HAVE_READV, CFA_HAVE_IORING_OP_READV or CFA_HAVE_IORING_OP_READ defined
			#endif

			asm volatile("": : :"memory");

			/* paranoid */ verify( sqe->user_data == (uintptr_t)&future );
			__submit_only( ctx, &idx, 1 );

			/* paranoid */ verify( proc == __cfaabi_tls.this_processor );
			/* paranoid */ verify( ! __preemption_enabled() );

			return true;
		}

		void __cfa_io_idle( struct processor * proc ) {
			iovec iov;
			__atomic_acquire( &proc->io.ctx->cq.lock );

			__attribute__((used)) volatile bool was_reset = false;

			with( proc->idle_wctx) {

				// Do we already have a pending read
				if(available(*ftr)) {
					// There is no pending read, we need to add one
					reset(*ftr);

					iov.iov_base = rdbuf;
					iov.iov_len  = sizeof(eventfd_t);
					__kernel_read(proc, *ftr, iov, evfd );
					ftr->result = 0xDEADDEAD;
					*((eventfd_t *)rdbuf) = 0xDEADDEADDEADDEAD;
					was_reset = true;
				}
			}

			if( !__atomic_load_n( &proc->do_terminate, __ATOMIC_SEQ_CST ) ) {
				__ioarbiter_flush( *proc->io.ctx );
				proc->idle_wctx.sleep_time = rdtscl();
				ioring_syscsll( *proc->io.ctx, 1, IORING_ENTER_GETEVENTS);
			}

			ready_schedule_lock();
			__cfa_do_drain( proc->io.ctx, proc->cltr );
			ready_schedule_unlock();

			asm volatile ("" :: "m" (was_reset));
		}
	#endif
#endif