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c84899c636
Now that the event handler API is pretty mature, we can expose it in the lua API. Introducing the core.event_sub(<event_types>, <cb>) lua function that takes an array of event types <event_types> as well as a callback function <cb> as argument. The function returns a subscription <sub> on success. Subscription <sub> allows you to manage the subscription from anywhere in the script. To this day only the sub->unsub method is implemented. The following event types are currently supported: - "SERVER_ADD": when a server is added - "SERVER_DEL": when a server is removed from haproxy - "SERVER_DOWN": server states goes from up to down - "SERVER_UP": server states goes from down to up As for the <cb> function: it will be called when one of the registered event types occur. The function will be called with 3 arguments: cb(<event>,<data>,<sub>) <event>: event type (string) that triggered the function. (could be any of the types used in <event_types> when registering the subscription) <data>: data associated with the event (specific to each event family). For "SERVER_" family events, server details such as server name/id/proxy will be provided. If the server still exists (not yet deleted), a reference to the live server is provided to spare you from an additionnal lookup if you need to have direct access to the server from lua. <sub> refers to the subscription. In case you need to manage it from within an event handler. (It refers to the same subscription that the one returned from core.event_sub()) Subscriptions are per-thread: the thread that will be handling the event is the one who performed the subscription using core.event_sub() function. Each thread treats events sequentially, it means that if you have, let's say SERVER_UP, then SERVER_DOWN in a short timelapse, then your cb function will first be called with SERVER_UP, and once you're done handling the event, your function will be called again with SERVER_DOWN. This is to ensure event consitency when it comes to logging / triggering logic from lua. Your lua cb function may yield if needed, but you're pleased to process the event as fast as possible to prevent the event queue from growing up To prevent abuses, if the event queue for the current subscription goes over 100 unconsumed events, the subscription will pause itself automatically for as long as it takes for your handler to catch up. This would lead to events being missed, so a warning will be emitted in the logs to inform you about that. This is not something you want to let happen too often, it may indicate that you subscribed to an event that is occurring too frequently or/and that your callback function is too slow to keep up the pace and you should review it. If you want to do some parallel processing because your callback functions are slow: you might want to create subtasks from lua using core.register_task() from within your callback function to perform the heavy job in a dedicated task and allow remaining events to be processed more quickly. Please check the lua documentation for more information.
77 lines
3.1 KiB
C
77 lines
3.1 KiB
C
/*
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* include/haproxy/hlua.h
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* Lua core management functions
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*
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* Copyright (C) 2015-2016 Thierry Fournier <tfournier@arpalert.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation, version 2.1
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* exclusively.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _HAPROXY_HLUA_H
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#define _HAPROXY_HLUA_H
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#include <haproxy/hlua-t.h>
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#ifdef USE_LUA
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/* The following macros are used to set flags. */
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#define HLUA_SET_RUN(__hlua) do {(__hlua)->flags |= HLUA_RUN;} while(0)
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#define HLUA_CLR_RUN(__hlua) do {(__hlua)->flags &= ~HLUA_RUN;} while(0)
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#define HLUA_IS_RUNNING(__hlua) ((__hlua)->flags & HLUA_RUN)
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#define HLUA_SET_CTRLYIELD(__hlua) do {(__hlua)->flags |= HLUA_CTRLYIELD;} while(0)
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#define HLUA_CLR_CTRLYIELD(__hlua) do {(__hlua)->flags &= ~HLUA_CTRLYIELD;} while(0)
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#define HLUA_IS_CTRLYIELDING(__hlua) ((__hlua)->flags & HLUA_CTRLYIELD)
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#define HLUA_SET_WAKERESWR(__hlua) do {(__hlua)->flags |= HLUA_WAKERESWR;} while(0)
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#define HLUA_CLR_WAKERESWR(__hlua) do {(__hlua)->flags &= ~HLUA_WAKERESWR;} while(0)
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#define HLUA_IS_WAKERESWR(__hlua) ((__hlua)->flags & HLUA_WAKERESWR)
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#define HLUA_SET_WAKEREQWR(__hlua) do {(__hlua)->flags |= HLUA_WAKEREQWR;} while(0)
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#define HLUA_CLR_WAKEREQWR(__hlua) do {(__hlua)->flags &= ~HLUA_WAKEREQWR;} while(0)
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#define HLUA_IS_WAKEREQWR(__hlua) ((__hlua)->flags & HLUA_WAKEREQWR)
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#define HLUA_CLR_NOYIELD(__hlua) do {(__hlua)->flags &= ~HLUA_NOYIELD;} while(0)
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#define HLUA_SET_NOYIELD(__hlua) do {(__hlua)->flags |= HLUA_NOYIELD;} while(0)
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#define HLUA_CANT_YIELD(__hlua) ((__hlua)->flags & HLUA_NOYIELD)
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#define HLUA_INIT(__hlua) do { (__hlua)->T = 0; } while(0)
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/* Lua HAProxy integration functions. */
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const char *hlua_traceback(lua_State *L, const char* sep);
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void hlua_ctx_destroy(struct hlua *lua);
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void hlua_init();
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int hlua_post_init();
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void hlua_applet_tcp_fct(struct appctx *ctx);
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void hlua_applet_http_fct(struct appctx *ctx);
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int hlua_event_sub(lua_State *L, event_hdl_sub_list *sub_list);
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struct task *hlua_process_task(struct task *task, void *context, unsigned int state);
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const char *hlua_show_current_location(const char *pfx);
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#else /* USE_LUA */
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/************************ For use when Lua is disabled ********************/
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#define HLUA_IS_RUNNING(__hlua) 0
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#define HLUA_INIT(__hlua)
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/* Empty function for compilation without Lua. */
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static inline void hlua_init() { }
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static inline int hlua_post_init() { return 1; }
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static inline void hlua_ctx_destroy(struct hlua *lua) { }
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static inline const char *hlua_show_current_location(const char *pfx) { return NULL; }
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#endif /* USE_LUA */
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#endif /* _HAPROXY_HLUA_H */
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