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/*
* Event queue support for PMDAs
*
* Copyright (c) 2011 Red Hat Inc.
* Copyright (c) 2011 Nathan Scott. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* This program 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 General Public License
* for more details.
*
* Portions Copyright (c) 1991, 1993
*
* The Regents of the University of California. All rights reserved.
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef _QUEUES_H
#define _QUEUES_H
/*
* Extracts of TAILQ implementation from <sys/queue.h> included directly
* for platforms without support (Win32, older Linux variants).
*
* A tail queue is headed by a pair of pointers, one to the head of the
* list and the other to the tail of the list. The elements are doubly
* linked so that an arbitrary element can be removed without a need to
* traverse the list. New elements can be added to the list before or
* after an existing element, at the head of the list, or at the end of
* the list. A tail queue may be traversed in either direction.
*
* For details on the use of these macros, see the queue(3) manual page.
*/
#define _TAILQ_HEAD(name, type, qual) \
struct name { \
qual type *tqh_first; /* first element */ \
qual type *qual *tqh_last; /* addr of last next element */ \
}
#define TAILQ_HEAD(name, type) _TAILQ_HEAD(name, struct type,)
#define _TAILQ_ENTRY(type, qual) \
struct { \
qual type *tqe_next; /* next element */ \
qual type *qual *tqe_prev; /* address of previous next element */\
}
#define TAILQ_ENTRY(type) _TAILQ_ENTRY(struct type,)
#define TAILQ_INIT(head) do { \
(head)->tqh_first = NULL; \
(head)->tqh_last = &(head)->tqh_first; \
} while (0)
#define TAILQ_INSERT_HEAD(head, elm, field) do { \
if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
(head)->tqh_first->field.tqe_prev = \
&(elm)->field.tqe_next; \
else \
(head)->tqh_last = &(elm)->field.tqe_next; \
(head)->tqh_first = (elm); \
(elm)->field.tqe_prev = &(head)->tqh_first; \
} while (0)
#define TAILQ_INSERT_TAIL(head, elm, field) do { \
(elm)->field.tqe_next = NULL; \
(elm)->field.tqe_prev = (head)->tqh_last; \
*(head)->tqh_last = (elm); \
(head)->tqh_last = &(elm)->field.tqe_next; \
} while (0)
#define TAILQ_REMOVE(head, elm, field) do { \
if (((elm)->field.tqe_next) != NULL) \
(elm)->field.tqe_next->field.tqe_prev = \
(elm)->field.tqe_prev; \
else \
(head)->tqh_last = (elm)->field.tqe_prev; \
*(elm)->field.tqe_prev = (elm)->field.tqe_next; \
} while (0)
#define TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
#define TAILQ_FIRST(head) ((head)->tqh_first)
#define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
#define TAILQ_LAST(head, headname) \
(*(((struct headname *)((head)->tqh_last))->tqh_last))
#define TAILQ_PREV(elm, headname, field) \
(*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
/*
* Data structures used in the PMDA event queue implementation
* Every event is timestamped and linked into one (tail) queue.
* Events know nothing about the clients accessing them.
*/
typedef struct event {
TAILQ_ENTRY(event) events; /* link into queue of events */
struct timeval time; /* timestamp for this event */
int count; /* events reference count */
size_t size; /* buffer size in bytes */
char buffer[];
} event_t;
TAILQ_HEAD(tailqueue, event);
typedef struct event_queue {
const char *name; /* callers identifier for this queue */
size_t maxmemory; /* max data bytes that can be queued */
int inuse; /* is this queue in use or free */
int eventarray; /* event records for this queue */
__uint32_t numclients; /* export: number of active clients */
__uint32_t count; /* exported: event counter */
__uint64_t bytes; /* exported: data throughput */
__uint64_t qsize; /* data in the queue (<= maxmem) */
struct tailqueue tailq; /* queue of events for clients */
} event_queue_t;
/*
* Data structures used in the PMDA event client implementation
* Each client is one PCP tool invocation (e.g. pmevent) and has
* a link back to those queues which it has fetched/stored into
* at some point in the past. The "last" event pointer, gives a
* pointer to the last observed event for that client, which is
* used as the starting point for a subsequent fetch request (or
* when dropping events, should the client not be keeping up).
*/
typedef struct event_clientq {
int active; /* client interest in this queue */
int missed; /* count of events missed on queue */
int access; /* is access restricted/permitted */
event_t *last; /* last event seen on this queue */
void *filter; /* filter data for the event queue */
pmdaEventApplyFilterCallBack apply; /* actual filter callback */
pmdaEventReleaseFilterCallBack release; /* remove filter callback */
} event_clientq_t;
typedef struct event_client {
int context; /* client context identifier */
int inuse; /* is this table slot in use */
int nclientq; /* allocated size of clientq */
event_clientq_t *clientq; /* per-queue client state */
} event_client_t;
#endif /* _QUEUES_H */
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