Aurelien DARRAGON 983513d901 DEBUG: hlua: distinguish burst timeout errors from exec timeout errors
hlua burst timeout was introduced in 58e36e5b1 ("MEDIUM: hlua: introduce
tune.lua.burst-timeout").

It is a safety measure that allows to detect when too much time is spent
on a single lua execution (between 2 interruptions/yields), meaning that
the current thread is not able to perform other tasks. Such scenario
should be avoided because it will cause thread contention which may have
negative performance impact and could cause the watchdog to trigger. When
the burst timeout is exceeded, the current Lua execution is aborted and a
timeout error is reported to the user.

Unfortunately, the same error is currently being reported for cumulative
(AKA execution) timeout and for burst timeout, which may be confusing to
the user.

Indeed, "execution timeout" error historically results from the current
hlua context exceeding the total (cumulative) time it's allowed to run.
It is set per lua context using the dedicated tunables:
 - tune.lua.session-timeout
 - tune.lua.task-timeout
 - tune.lua.service-timeout

We've already faced an user report where the user was able to trigger the
burst timeout and got "Lua task: execution timeout." error while the user
didn't set cumulative timeout. Thus the error was actually confusing
because it was indeed the burst timeout which was causing it due to the
use of cpu-intensive call from within the task without sufficient manual
"yield" keypoints around the cpu-intensive call to ensure it runs on a
dedicated scheduler cycle.

In this patch we make it so burst timeout related errors are reported as
"burst timeout" errors instead of "execution timeout" errors (which
in fact became the generic timeout errors catchall with 58e36e5b1).

To do this, hlua_timer_check() now returns a different value depending if
the exeeded timeout is the burst one or the cumulative one, which allows
us to return either HLUA_E_ETMOUT or HLUA_E_BTMOUT in hlua_ctx_resume().

It should improve the situation described in GH #2356 and may possibly be
backported with 58e36e5b1 to improve error reporting if it applies without
resistance.
2024-06-14 18:25:58 +02:00

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C

/*
* include/haproxy/hlua-t.h
* Lua core types definitions
*
* Copyright (C) 2015-2016 Thierry Fournier <tfournier@arpalert.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _HAPROXY_HLUA_T_H
#define _HAPROXY_HLUA_T_H
#ifdef USE_LUA
#include <lua.h>
#include <lauxlib.h>
#include <stdint.h>
#include <import/ebtree-t.h>
#include <haproxy/proxy-t.h>
#include <haproxy/regex-t.h>
#include <haproxy/server-t.h>
#include <haproxy/stick_table-t.h>
#include <haproxy/xref-t.h>
#include <haproxy/event_hdl-t.h>
#define CLASS_CORE "Core"
#define CLASS_TXN "TXN"
#define CLASS_FETCHES "Fetches"
#define CLASS_CONVERTERS "Converters"
#define CLASS_SOCKET "Socket"
#define CLASS_CHANNEL "Channel"
#define CLASS_HTTP "HTTP"
#define CLASS_HTTP_MSG "HTTPMessage"
#define CLASS_HTTPCLIENT "HTTPClient"
#define CLASS_MAP "Map"
#define CLASS_APPLET_TCP "AppletTCP"
#define CLASS_APPLET_HTTP "AppletHTTP"
#define CLASS_PROXY "Proxy"
#define CLASS_SERVER "Server"
#define CLASS_LISTENER "Listener"
#define CLASS_EVENT_SUB "EventSub"
#define CLASS_REGEX "Regex"
#define CLASS_STKTABLE "StickTable"
#define CLASS_CERTCACHE "CertCache"
#define CLASS_PROXY_LIST "ProxyList"
#define CLASS_SERVER_LIST "ServerList"
struct stream;
#define HLUA_RUN 0x00000001
#define HLUA_CTRLYIELD 0x00000002
#define HLUA_WAKERESWR 0x00000004
#define HLUA_WAKEREQWR 0x00000008
#define HLUA_EXIT 0x00000010
#define HLUA_NOYIELD 0x00000020
#define HLUA_BUSY 0x00000040
#define HLUA_F_AS_STRING 0x01
#define HLUA_F_MAY_USE_HTTP 0x02
/* HLUA TXN flags */
#define HLUA_TXN_NOTERM 0x00000001
/* 0x00000002 .. 0x00000008 unused */
/* The execution context (enum), bits values from 0x00000010 to
* 0x00000030. These flags are mutually exclusives. Only one must be set at a
* time.
*/
#define HLUA_TXN_SMP_NONE 0x00000000 /* No specific execution context */
#define HLUA_TXN_SMP_CTX 0x00000010 /* Executed from a sample fecth context */
#define HLUA_TXN_ACT_CTX 0x00000020 /* Executed from a action context */
#define HLUA_TXN_FLT_CTX 0x00000030 /* Executed from a filter context */
#define HLUA_TXN_CTX_MASK 0x00000030 /* Mask to get the execution context */
#define HLUA_CONCAT_BLOCSZ 2048
enum hlua_exec {
HLUA_E_OK = 0,
HLUA_E_AGAIN, /* LUA yield, must resume the stack execution later, when
the associatedtask is waked. */
HLUA_E_ETMOUT, /* Execution timeout */
HLUA_E_BTMOUT, /* Burst timeout */
HLUA_E_NOMEM, /* Out of memory error */
HLUA_E_YIELD, /* LUA code try to yield, and this is not allowed */
HLUA_E_ERRMSG, /* LUA stack execution failed with a string error message
in the top of stack. */
HLUA_E_ERR, /* LUA stack execution failed without error message. */
};
struct hlua_timer {
uint32_t start; /* cpu time in ms when the timer was started */
uint32_t burst; /* execution time for the current call in ms */
uint32_t cumulative; /* cumulative execution time for the coroutine in ms */
uint32_t max; /* max (cumulative) execution time for the coroutine in ms */
};
struct hlua {
lua_State *T; /* The LUA stack. */
int state_id; /* contains the lua state id. 0 is common state, 1 to n are per-thread states.*/
int Tref; /* The reference of the stack in coroutine case.
-1 for the main lua stack. */
int Mref; /* The reference of the memory context in coroutine case.
-1 if the memory context is not used. */
int nargs; /* The number of arguments in the stack at the start of execution. */
unsigned int flags; /* The current execution flags. */
int wake_time; /* The lua wants to be waked at this time, or before. (ticks) */
struct hlua_timer timer; /* lua multipurpose timer */
struct task *task; /* The task associated with the lua stack execution.
We must wake this task to continue the task execution */
struct list com; /* The list head of the signals attached to this task. */
struct mt_list hc_list; /* list of httpclient associated to this lua task */
struct ebpt_node node;
int gc_count; /* number of items which need a GC */
};
/* This is a part of the list containing references to functions
* called at the initialisation time.
*/
struct hlua_init_function {
struct list l;
int function_ref;
};
/* This struct contains the lua data used to bind
* Lua function on HAProxy hook like sample-fetches
* or actions.
*/
struct hlua_function {
struct list l;
char *name;
int function_ref[MAX_THREADS + 1];
int nargs;
};
/* This struct is used with the structs:
* - http_req_rule
* - http_res_rule
* - tcp_rule
* It contains the lua execution configuration.
*/
struct hlua_rule {
struct hlua_function *fcn;
char **args;
};
/* This struct contains the pointer provided on the most
* of internal HAProxy calls during the processing of
* rules, converters and sample-fetches. This struct is
* associated with the lua object called "TXN".
*/
struct hlua_txn {
struct stream *s;
struct proxy *p;
int dir; /* SMP_OPT_DIR_{REQ,RES} */
int flags;
};
/* This struct contains the applet context. */
struct hlua_appctx {
struct appctx *appctx;
luaL_Buffer b; /* buffer used to prepare strings. */
struct hlua_txn htxn;
};
/* This struct is used with sample fetches and sample converters. */
struct hlua_smp {
struct stream *s;
struct proxy *p;
unsigned int flags; /* LUA_F_OPT_* */
int dir; /* SMP_OPT_DIR_{REQ,RES} */
};
/* This struct contains data used with sleep functions. */
struct hlua_sleep {
struct task *task; /* task associated with sleep. */
struct list com; /* list of signal to wake at the end of sleep. */
unsigned int wakeup_ms; /* hour to wakeup. */
};
/* This struct is used to create coprocess doing TCP or
* SSL I/O. It uses a fake stream.
*/
struct hlua_socket {
struct xref xref; /* cross reference with the stream used for socket I/O. */
luaL_Buffer b; /* buffer used to prepare strings. */
unsigned long tid; /* Store the thread id which creates the socket. */
};
struct hlua_concat {
int size;
int len;
};
/* This struct is used to store the httpclient */
struct hlua_httpclient {
struct httpclient *hc; /* ptr to the httpclient instance */
size_t sent; /* payload sent */
luaL_Buffer b; /* buffer used to prepare strings. */
struct mt_list by_hlua; /* linked in the current hlua task */
};
struct hlua_proxy_list {
char capabilities;
};
struct hlua_proxy_list_iterator_context {
struct proxy *next;
char capabilities;
};
struct hlua_server_list {
struct proxy *px;
};
struct hlua_server_list_iterator_context {
struct server *cur;
struct proxy *px;
};
#else /* USE_LUA */
/************************ For use when Lua is disabled ********************/
/* Empty struct for compilation compatibility */
struct hlua { };
struct hlua_socket { };
struct hlua_rule { };
#endif /* USE_LUA */
#endif /* _HAPROXY_HLUA_T_H */