// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.

#if __has_include("db/write_thread.h")
	#define ROCKSDB_PLATFORM_POSIX
	#include "db/write_thread.h"
#endif

#ifndef STORAGE_ROCKSDB_INCLUDE_DB_H_
	#warning "The RocksDB source code is not available. Cannot interpose bugfixes for db/write_thread.h."
#endif

#ifdef STORAGE_ROCKSDB_INCLUDE_DB_H_
uint8_t
__attribute__((externally_visible))
rocksdb::WriteThread::BlockingAwaitState(Writer *const w,
                                         uint8_t goal_mask)
{
	// Create the class member mutex and cv where it's expected by
	// rocksdb callers
	w->CreateMutex();

	auto state(w->state.load(std::memory_order_acquire));
	assert(state != STATE_LOCKED_WAITING);
	if((state & goal_mask) == 0 && w->state.compare_exchange_strong(state, STATE_LOCKED_WAITING))
	{
		size_t yields(0);
		while((state = w->state.load(std::memory_order_relaxed)) == STATE_LOCKED_WAITING)
		{
			ircd::ctx::yield();
			++yields;
		}

		// Since we're using a coarse ctx::yield() it's theoretically possible
		// that our loop can spin out of control. That is highly unlikely,
		// and there is usually not even more than one iteration. Nevertheless
		// we assert to be sure this is working within reason.
		assert(yields < 32);
	}

	assert((state & goal_mask) != 0);
	return state;
}
#endif STORAGE_ROCKSDB_INCLUDE_DB_H_