APACHE_1_3_42/src/include/scoreboard.h

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef APACHE_SCOREBOARD_H
#define APACHE_SCOREBOARD_H

#ifdef __cplusplus
extern "C" {
#endif

#ifndef WIN32
#if defined(TPF41) || defined(NETWARE)
#include <time.h>
#else
#include <sys/times.h>
#endif /* TPF41 || NETWARE */
#endif


/* Scoreboard info on a process is, for now, kept very brief --- 
 * just status value and pid (the latter so that the caretaker process
 * can properly update the scoreboard when a process dies).  We may want
 * to eventually add a separate set of long_score structures which would
 * give, for each process, the number of requests serviced, and info on
 * the current, or most recent, request.
 *
 * Status values:
 */

#define SERVER_DEAD 0
#define SERVER_STARTING 1	/* Server Starting up */
#define SERVER_READY 2		/* Waiting for connection (or accept() lock) */
#define SERVER_BUSY_READ 3	/* Reading a client request */
#define SERVER_BUSY_WRITE 4	/* Processing a client request */
#define SERVER_BUSY_KEEPALIVE 5	/* Waiting for more requests via keepalive */
#define SERVER_BUSY_LOG 6	/* Logging the request */
#define SERVER_BUSY_DNS 7	/* Looking up a hostname */
#define SERVER_GRACEFUL 8	/* server is gracefully finishing request */
#define SERVER_NUM_STATUS 9	/* number of status settings */

/* A "virtual time" is simply a counter that indicates that a child is
 * making progress.  The parent checks up on each child, and when they have
 * made progress it resets the last_rtime element.  But when the child hasn't
 * made progress in a time that's roughly timeout_len seconds long, it is
 * sent a SIGALRM.
 *
 * vtime is an optimization that is used only when the scoreboard is in
 * shared memory (it's not easy/feasible to do it in a scoreboard file).
 * The essential observation is that timeouts rarely occur, the vast majority
 * of hits finish before any timeout happens.  So it really sucks to have to
 * ask the operating system to set up and destroy alarms many times during
 * a request.
 */
typedef unsigned vtime_t;

/* Type used for generation indicies.  Startup and every restart cause a
 * new generation of children to be spawned.  Children within the same
 * generation share the same configuration information -- pointers to stuff
 * created at config time in the parent are valid across children.  For
 * example, the vhostrec pointer in the scoreboard below is valid in all
 * children of the same generation.
 *
 * The safe way to access the vhost pointer is like this:
 *
 * short_score *ss = pointer to whichver slot is interesting;
 * parent_score *ps = pointer to whichver slot is interesting;
 * server_rec *vh = ss->vhostrec;
 *
 * if (ps->generation != ap_my_generation) {
 *     vh = NULL;
 * }
 *
 * then if vh is not NULL it's valid in this child.
 *
 * This avoids various race conditions around restarts.
 */
typedef int ap_generation_t;

/* stuff which the children generally write, and the parent mainly reads */
typedef struct {
#ifdef OPTIMIZE_TIMEOUTS
    vtime_t cur_vtime;		/* the child's current vtime */
    unsigned short timeout_len;	/* length of the timeout */
#endif
    unsigned char status;
    unsigned long access_count;
    unsigned long bytes_served;
    unsigned long my_access_count;
    unsigned long my_bytes_served;
    unsigned long conn_bytes;
    unsigned short conn_count;
#if defined(NO_GETTIMEOFDAY)
    clock_t start_time;
    clock_t stop_time;
#else
    struct timeval start_time;
    struct timeval stop_time;
#endif
#ifndef NO_TIMES
    struct tms times;
#endif
#ifndef OPTIMIZE_TIMEOUTS
    time_t last_used;
#endif
    char client[32];		/* Keep 'em small... */
    char request[64];		/* We just want an idea... */
    server_rec *vhostrec;	/* What virtual host is being accessed? */
                                /* SEE ABOVE FOR SAFE USAGE! */
} short_score;

typedef struct {
    ap_generation_t running_generation;	/* the generation of children which
                                         * should still be serving requests. */
} global_score;

/* stuff which the parent generally writes and the children rarely read */
typedef struct {
    pid_t pid;
#ifdef OPTIMIZE_TIMEOUTS
    time_t last_rtime;		/* time(0) of the last change */
    vtime_t last_vtime;		/* the last vtime the parent has seen */
#endif
    ap_generation_t generation;	/* generation of this child */
} parent_score;

typedef struct {
    short_score servers[HARD_SERVER_LIMIT];
    parent_score parent[HARD_SERVER_LIMIT];
    global_score global;
} scoreboard;

#define SCOREBOARD_SIZE		sizeof(scoreboard)

API_EXPORT(void) ap_sync_scoreboard_image(void);
API_EXPORT(int) ap_exists_scoreboard_image(void);

API_VAR_EXPORT extern scoreboard *ap_scoreboard_image;

API_VAR_EXPORT extern ap_generation_t volatile ap_my_generation;

/* for time_process_request() in http_main.c */
#define START_PREQUEST 1
#define STOP_PREQUEST  2

#ifdef __cplusplus
}
#endif

#endif	/* !APACHE_SCOREBOARD_H */