include/mpm_common.h

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
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 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
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 *    not be used to endorse or promote products derived from this
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 * 5. Products derived from this software may not be called "Apache",
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

/* The purpose of this file is to store the code that MOST mpm's will need
 * this does not mean a function only goes into this file if every MPM needs
 * it.  It means that if a function is needed by more than one MPM, and
 * future maintenance would be served by making the code common, then the
 * function belongs here.
 *
 * This is going in src/main because it is not platform specific, it is
 * specific to multi-process servers, but NOT to Unix.  Which is why it
 * does not belong in src/os/unix
 */

#ifndef APACHE_MPM_COMMON_H
#define APACHE_MPM_COMMON_H

#include "ap_config.h"

#if APR_HAVE_NETINET_TCP_H
#include <netinet/tcp.h>    /* for TCP_NODELAY */
#endif

#include "mpm.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @package Multi-Processing Modules functions
 */

/* The maximum length of the queue of pending connections, as defined
 * by listen(2).  Under some systems, it should be increased if you
 * are experiencing a heavy TCP SYN flood attack.
 *
 * It defaults to 511 instead of 512 because some systems store it 
 * as an 8-bit datatype; 512 truncated to 8-bits is 0, while 511 is 
 * 255 when truncated.
 */
#ifndef DEFAULT_LISTENBACKLOG
#define DEFAULT_LISTENBACKLOG 511
#endif
        
/**
 * Make sure all child processes that have been spawned by the parent process
 * have died.  This includes process registered as "other_children".
 * @warning This is only defined if the MPM defines 
 *          MPM_NEEDS_RECLAIM_CHILD_PROCESS
 * @param terminate Either 1 or 0.  If 1, send the child processes SIGTERM
 *        each time through the loop.  If 0, give the process time to die
 *        on its own before signalling it.
 * @tip This function requires that some macros are defined by the MPM: <pre>
 *  MPM_SYNC_CHILD_TABLE -- sync the scoreboard image between child and parent
 *  MPM_CHILD_PID -- Get the pid from the specified spot in the scoreboard
 *  MPM_NOTE_CHILD_KILLED -- Note the child died in the scoreboard
 * </pre>
 */
#ifdef AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
void ap_reclaim_child_processes(int terminate);
#endif

/**
 * Determine if any child process has died.  If no child process died, then
 * this process sleeps for the amount of time specified by the MPM defined
 * macro SCOREBOARD_MAINTENANCE_INTERVAL.
 * @param status The return code if a process has died
 * @param ret The process id of the process that died
 * @param p The pool to allocate out of
 */
#ifdef AP_MPM_WANT_WAIT_OR_TIMEOUT
void ap_wait_or_timeout(apr_exit_why_e *status, int *exitcode, apr_proc_t *ret, 
                        apr_pool_t *p);
#endif

/**
 * Log why a child died to the error log, if the child died without the
 * parent signalling it.
 * @param pid The child that has died
 * @param status The status returned from ap_wait_or_timeout
 * @return 0 on success, APEXIT_CHILDFATAL if MPM should terminate
 */
#ifdef AP_MPM_WANT_PROCESS_CHILD_STATUS
int ap_process_child_status(apr_proc_t *pid, apr_exit_why_e why, int status);
#endif

#if defined(TCP_NODELAY) && !defined(MPE) && !defined(TPF)
/**
 * Turn off the nagle algorithm for the specified socket.  The nagle algorithm
 * says that we should delay sending partial packets in the hopes of getting
 * more data.  There are bad interactions between persistent connections and
 * Nagle's algorithm that have severe performance penalties.
 * @param s The socket to disable nagle for.
 */
void ap_sock_disable_nagle(apr_socket_t *s);
#else
#define ap_sock_disable_nagle(s)        /* NOOP */
#endif

#ifdef HAVE_GETPWNAM
/**
 * Convert a username to a numeric ID
 * @param name The name to convert
 * @return The user id corresponding to a name
 * @deffunc uid_t ap_uname2id(const char *name)
 */
AP_DECLARE(uid_t) ap_uname2id(const char *name);
#endif

#ifdef HAVE_GETGRNAM
/**
 * Convert a group name to a numeric ID
 * @param name The name to convert
 * @return The group id corresponding to a name
 * @deffunc gid_t ap_gname2id(const char *name)
 */
AP_DECLARE(gid_t) ap_gname2id(const char *name);
#endif

#define AP_MPM_HARD_LIMITS_FILE APACHE_MPM_DIR "/mpm_default.h"

#ifdef AP_MPM_USES_POD

typedef struct ap_pod_t ap_pod_t;

struct ap_pod_t {
    apr_file_t *pod_in;
    apr_file_t *pod_out;
    apr_pool_t *p;
    apr_sockaddr_t *sa;
};

/**
 * Open the pipe-of-death.  The pipe of death is used to tell all child
 * processes that it is time to die gracefully.
 * @param p The pool to use for allocating the pipe
 */
AP_DECLARE(apr_status_t) ap_mpm_pod_open(apr_pool_t *p, ap_pod_t **pod);

/**
 * Check the pipe to determine if the process has been signalled to die.
 */
AP_DECLARE(apr_status_t) ap_mpm_pod_check(ap_pod_t *pod);

/**
 * Close the pipe-of-death
 */
AP_DECLARE(apr_status_t) ap_mpm_pod_close(ap_pod_t *pod);

/**
 * Write data to the pipe-of-death, signalling that one child process
 * should die.
 * @param p The pool to use when allocating any required structures.
 */
AP_DECLARE(apr_status_t) ap_mpm_pod_signal(ap_pod_t *pod);

/**
 * Write data to the pipe-of-death, signalling that all child process
 * should die.
 * @param p The pool to use when allocating any required structures.
 * @param num The number of child processes to kill
 */
AP_DECLARE(void) ap_mpm_pod_killpg(ap_pod_t *pod, int num);
#endif

/*
 * These data members are common to all mpms. Each new mpm
 * should either use the appropriate ap_mpm_set_* function
 * in their command table or create their own for custom or
 * OS specific needs. These should work for most.
 */

/**
 * The maximum number of requests each child thread or
 * process handles before dying off
 */
#ifdef AP_MPM_WANT_SET_MAX_REQUESTS
extern int ap_max_requests_per_child;
const char *ap_mpm_set_max_requests(cmd_parms *cmd, void *dummy,
                                    const char *arg);
#endif

/**
 * The filename used to store the process id.
 */
#ifdef AP_MPM_WANT_SET_PIDFILE
extern const char *ap_pid_fname;
const char *ap_mpm_set_pidfile(cmd_parms *cmd, void *dummy,
                               const char *arg);
#endif

/**
 * The name of lockfile used when Apache needs to lock the accept() call.
 */
#ifdef AP_MPM_WANT_SET_LOCKFILE
extern const char *ap_lock_fname;
const char *ap_mpm_set_lockfile(cmd_parms *cmd, void *dummy,
                                const char *arg);
#endif

/**
 * The system mutex implementation to use for the accept mutex.
 */
#ifdef AP_MPM_WANT_SET_ACCEPT_LOCK_MECH
extern apr_lockmech_e ap_accept_lock_mech;
const char *ap_mpm_set_accept_lock_mech(cmd_parms *cmd, void *dummy,
                                        const char *arg);
#endif

/*
 * Set the scorboard file.
 */
#ifdef AP_MPM_WANT_SET_SCOREBOARD
const char *ap_mpm_set_scoreboard(cmd_parms *cmd, void *dummy,
                                  const char *arg);
#endif

/*
 * The directory that the server changes directory to dump core.
 */
#ifdef AP_MPM_WANT_SET_COREDUMPDIR
extern char ap_coredump_dir[MAX_STRING_LEN];
const char *ap_mpm_set_coredumpdir(cmd_parms *cmd, void *dummy,
                                   const char *arg);
#endif

#ifdef __cplusplus
}
#endif

#endif /* !APACHE_MPM_COMMON_H */