apache/include/mpm_common.h

/* ====================================================================
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 * 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

#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>
 */
void ap_reclaim_child_processes(int terminate);

/**
 * 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
 */
void ap_wait_or_timeout(apr_wait_t *status, apr_proc_t *ret, apr_pool_t *p);

/**
 * 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
 */
void ap_process_child_status(apr_proc_t *pid, apr_wait_t status);

#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

/**
 * 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);
/**
 * 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);

#define AP_MPM_HARD_LIMITS_FILE APACHE_MPM_DIR "/mpm_default.h"

#ifdef __cplusplus
}
#endif

#endif /* !APACHE_MPM_COMMON_H */