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construct/include/ircd/ctx/prof.h

63 lines
2.4 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 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.
#pragma once
#define HAVE_IRCD_CTX_PROF_H
/// Profiling for the context system.
///
/// These facilities provide tools and statistics. The primary purpose here is
/// to alert developers of unwanted context behavior, in addition to optimizing
/// the overall performance of the context system.
///
/// The original use case is for the embedded database backend. Function calls
/// are made which may conduct blocking I/O before returning. This will hang the
/// current userspace context while it is running and thus BLOCK EVERY CONTEXT
/// in the entire IRCd. Since this is still an asynchronous system, it just
/// doesn't have callbacks: we do not do I/O without a cooperative yield.
/// Fortunately there are mechanisms to mitigate this -- but we have to know
/// for sure. A database call which has been passed over for mitigation may
/// start doing some blocking flush under load, etc. The profiler will alert
/// us of this so it doesn't silently degrade performance.
///
namespace ircd::ctx::prof
{
enum class event;
struct settings extern settings;
const ulong &total_slice_cycles();
const ulong &cur_slice_start();
ulong cur_slice_cycles();
void mark(const event &);
}
enum class ircd::ctx::prof::event
{
SPAWN, // Context spawn requested
JOIN, // Context join requested
JOINED, // Context join completed
CUR_ENTER, // Current context entered
CUR_LEAVE, // Current context leaving
CUR_YIELD, // Current context yielding
CUR_CONTINUE, // Current context continuing
CUR_INTERRUPT, // Current context detects interruption
CUR_TERMINATE, // Current context detects termination
};
struct ircd::ctx::prof::settings
{
double stack_usage_warning; // percentage
double stack_usage_assertion; // percentage
ulong slice_warning; // Warn when the yield-to-yield cycles exceeds
ulong slice_interrupt; // Interrupt exception when exceeded (not a signal)
ulong slice_assertion; // abort() when exceeded (not a signal, must yield)
};