child.c

Apache 2.0.63 is the current stable version of the 2.0 series, and is recommended over any previous

/* 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.
 */

#ifdef WIN32

#define CORE_PRIVATE 
#include "httpd.h" 
#include "http_main.h" 
#include "http_log.h" 
#include "http_config.h"	/* for read_config */ 
#include "http_core.h"		/* for get_remote_host */ 
#include "http_connection.h"
#include "apr_portable.h"
#include "apr_thread_proc.h"
#include "apr_getopt.h"
#include "apr_strings.h"
#include "apr_lib.h"
#include "apr_shm.h"
#include "apr_thread_mutex.h"
#include "ap_mpm.h"
#include "ap_config.h"
#include "ap_listen.h"
#include "mpm_default.h"
#include "mpm_winnt.h"
#include "mpm_common.h"
#include <malloc.h>
#include "apr_atomic.h"

/* shared with mpm_winnt.c */
extern DWORD my_pid;

/* used by parent to signal the child to start and exit */
/* shared with mpm_winnt.c, but should be private to child.c */
apr_proc_mutex_t *start_mutex;
HANDLE exit_event;

/* child_main() should never need to modify is_graceful!?! */
extern int volatile is_graceful;

/* Queue for managing the passing of COMP_CONTEXTs between
 * the accept and worker threads.
 */
static apr_pool_t *pchild;
static int shutdown_in_progress = 0;
static int workers_may_exit = 0;
static unsigned int g_blocked_threads = 0;
static HANDLE max_requests_per_child_event;

static apr_thread_mutex_t  *child_lock;
static apr_thread_mutex_t  *qlock;
static PCOMP_CONTEXT qhead = NULL;
static PCOMP_CONTEXT qtail = NULL;
static int num_completion_contexts = 0;
static int max_num_completion_contexts = 0;
static HANDLE ThreadDispatchIOCP = NULL;
static HANDLE qwait_event = NULL;


AP_DECLARE(void) mpm_recycle_completion_context(PCOMP_CONTEXT context)
{
    /* Recycle the completion context.
     * - clear the ptrans pool
     * - put the context on the queue to be consumed by the accept thread
     * Note: 
     * context->accept_socket may be in a disconnected but reusable 
     * state so -don't- close it.
     */
    if (context) {
        apr_pool_clear(context->ptrans);
        context->ba = apr_bucket_alloc_create(context->ptrans);
        context->next = NULL;
        ResetEvent(context->Overlapped.hEvent);
        apr_thread_mutex_lock(qlock);
        if (qtail) {
            qtail->next = context;
        } else {
            qhead = context;
            SetEvent(qwait_event);
        }
        qtail = context;
        apr_thread_mutex_unlock(qlock);
    }
}

AP_DECLARE(PCOMP_CONTEXT) mpm_get_completion_context(void)
{
    apr_status_t rv;
    PCOMP_CONTEXT context = NULL;

    while (1) {
        /* Grab a context off the queue */
        apr_thread_mutex_lock(qlock);
        if (qhead) {
            context = qhead;
            qhead = qhead->next;
            if (!qhead)
                qtail = NULL;
        } else {
            ResetEvent(qwait_event);
        }
        apr_thread_mutex_unlock(qlock);
  
        if (!context) {
            /* We failed to grab a context off the queue, consider allocating
             * a new one out of the child pool. There may be up to 
             * (ap_threads_per_child + num_listeners) contexts in the system 
             * at once.
             */
            if (num_completion_contexts >= max_num_completion_contexts) {
                /* All workers are busy, need to wait for one */
                static int reported = 0;
                if (!reported) {
                    ap_log_error(APLOG_MARK, APLOG_WARNING, 0, ap_server_conf,
                                 "Server ran out of threads to serve requests. Consider "
                                 "raising the ThreadsPerChild setting");
                    reported = 1;
                }

                /* Wait for a worker to free a context. Once per second, give
                 * the caller a chance to check for shutdown. If the wait
                 * succeeds, get the context off the queue. It must be available,
                 * since there's only one consumer.
                 */
                rv = WaitForSingleObject(qwait_event, 1000);
                if (rv == WAIT_OBJECT_0)
                    continue;
                else /* Hopefully, WAIT_TIMEOUT */
                    return NULL;
            } else {
                /* Allocate another context.
                 * Note:
                 * Multiple failures in the next two steps will cause the pchild pool
                 * to 'leak' storage. I don't think this is worth fixing...
                 */
                apr_allocator_t *allocator;

                apr_thread_mutex_lock(child_lock);
                context = (PCOMP_CONTEXT) apr_pcalloc(pchild, sizeof(COMP_CONTEXT));
  
                context->Overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
                if (context->Overlapped.hEvent == NULL) {
                    /* Hopefully this is a temporary condition ... */
                    ap_log_error(APLOG_MARK,APLOG_WARNING, apr_get_os_error(), ap_server_conf,
                                 "mpm_get_completion_context: CreateEvent failed.");

                    apr_thread_mutex_unlock(child_lock);
                    return NULL;
                }
 
                /* Create the tranaction pool */
                apr_allocator_create(&allocator);
                apr_allocator_max_free_set(allocator, ap_max_mem_free);
                rv = apr_pool_create_ex(&context->ptrans, pchild, NULL, allocator);
                if (rv != APR_SUCCESS) {
                    ap_log_error(APLOG_MARK,APLOG_WARNING, rv, ap_server_conf,
                                 "mpm_get_completion_context: Failed to create the transaction pool.");
                    CloseHandle(context->Overlapped.hEvent);

                    apr_thread_mutex_unlock(child_lock);
                    return NULL;
                }
                apr_allocator_owner_set(allocator, context->ptrans);
                apr_pool_tag(context->ptrans, "transaction");
                context->accept_socket = INVALID_SOCKET;
                context->ba = apr_bucket_alloc_create(context->ptrans);
                apr_atomic_inc(&num_completion_contexts); 

                apr_thread_mutex_unlock(child_lock);
                break;
            }
        } else {
            /* Got a context from the queue */
            break;
        }
    }

    return context;
}

AP_DECLARE(apr_status_t) mpm_post_completion_context(PCOMP_CONTEXT context, 
                                                     io_state_e state)
{
    LPOVERLAPPED pOverlapped;
    if (context)
        pOverlapped = &context->Overlapped;
    else
        pOverlapped = NULL;

    PostQueuedCompletionStatus(ThreadDispatchIOCP, 0, state, pOverlapped);
    return APR_SUCCESS;
}


/*
 * find_ready_listener()
 * Only used by Win9* and should go away when the win9*_accept() function is 
 * reimplemented using apr_poll().
 */
static ap_listen_rec *head_listener;

static APR_INLINE ap_listen_rec *find_ready_listener(fd_set * main_fds)
{
    ap_listen_rec *lr;
    SOCKET nsd;

    lr = head_listener;
    do {
        apr_os_sock_get(&nsd, lr->sd);
        if (FD_ISSET(nsd, main_fds)) {
            head_listener = lr->next;
            if (!head_listener) {
                head_listener = ap_listeners;
            }
            return lr;
        }
        lr = lr->next;
        if (!lr) {
            lr = ap_listeners;
        }
    } while (lr != head_listener);
    return NULL;
}


/* Windows 9x specific code...
 * Accept processing for on Windows 95/98 uses a producer/consumer queue 
 * model. A single thread accepts connections and queues the accepted socket 
 * to the accept queue for consumption by a pool of worker threads.
 *
 * win9x_accept()
 *    The accept threads runs this function, which accepts connections off 
 *    the network and calls add_job() to queue jobs to the accept_queue.
 * add_job()/remove_job()
 *    Add or remove an accepted socket from the list of sockets 
 *    connected to clients. allowed_globals.jobmutex protects
 *    against multiple concurrent access to the linked list of jobs.
 * win9x_get_connection()
 *    Calls remove_job() to pull a job from the accept queue. All the worker 
 *    threads block on remove_job.
 */

typedef struct joblist_s {
    struct joblist_s *next;
    int sock;
} joblist;

typedef struct globals_s {
    HANDLE jobsemaphore;
    joblist *jobhead;
    joblist *jobtail;
    apr_thread_mutex_t *jobmutex;
    int jobcount;
} globals;

globals allowed_globals = {NULL, NULL, NULL, NULL, 0};

#define MAX_SELECT_ERRORS 100


static void add_job(int sock)
{
    joblist *new_job;

    new_job = (joblist *) malloc(sizeof(joblist));
    if (new_job == NULL) {
	ap_log_error(APLOG_MARK, APLOG_STARTUP, 0, NULL, 
                     "Ouch!  Out of memory in add_job()!");
        return;
    }
    new_job->next = NULL;
    new_job->sock = sock;

    apr_thread_mutex_lock(allowed_globals.jobmutex);

    if (allowed_globals.jobtail != NULL)
	allowed_globals.jobtail->next = new_job;
    allowed_globals.jobtail = new_job;
    if (!allowed_globals.jobhead)
	allowed_globals.jobhead = new_job;
    allowed_globals.jobcount++;
    ReleaseSemaphore(allowed_globals.jobsemaphore, 1, NULL);

    apr_thread_mutex_unlock(allowed_globals.jobmutex);
}


static int remove_job(void)
{
    joblist *job;
    int sock;

    WaitForSingleObject(allowed_globals.jobsemaphore, INFINITE);
    apr_thread_mutex_lock(allowed_globals.jobmutex);

    if (shutdown_in_progress && !allowed_globals.jobhead) {
        apr_thread_mutex_unlock(allowed_globals.jobmutex);
	return (INVALID_SOCKET);
    }
    job = allowed_globals.jobhead;
    ap_assert(job);
    allowed_globals.jobhead = job->next;
    if (allowed_globals.jobhead == NULL)
	allowed_globals.jobtail = NULL;
    apr_thread_mutex_unlock(allowed_globals.jobmutex);
    sock = job->sock;
    free(job);

    return (sock);
}


static unsigned int __stdcall win9x_accept(void * dummy)
{
    struct timeval tv;
    fd_set main_fds;
    int wait_time = 1;
    int csd;
    SOCKET nsd = INVALID_SOCKET;
    struct sockaddr_in sa_client;
    int count_select_errors = 0;
    int rc;
    int clen;
    ap_listen_rec *lr;
    struct fd_set listenfds;
    SOCKET listenmaxfd = INVALID_SOCKET;

    /* Setup the listeners 
     * ToDo: Use apr_poll()
     */
    FD_ZERO(&listenfds);
    for (lr = ap_listeners; lr; lr = lr->next) {
        if (lr->sd != NULL) {
            apr_os_sock_get(&nsd, lr->sd);
            FD_SET(nsd, &listenfds);
            if (listenmaxfd == INVALID_SOCKET || nsd > listenmaxfd) {
                listenmaxfd = nsd;
            }
            ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf,
                         "Child %d: Listening on port %d.", my_pid, lr->bind_addr->port);
        }
    }

    head_listener = ap_listeners;

    while (!shutdown_in_progress) {
	tv.tv_sec = wait_time;
	tv.tv_usec = 0;
	memcpy(&main_fds, &listenfds, sizeof(fd_set));

	rc = select(listenmaxfd + 1, &main_fds, NULL, NULL, &tv);

        if (rc == 0 || (rc == SOCKET_ERROR && APR_STATUS_IS_EINTR(apr_get_netos_error()))) {
            count_select_errors = 0;    /* reset count of errors */            
            continue;
        }
        else if (rc == SOCKET_ERROR) {
            /* A "real" error occurred, log it and increment the count of
             * select errors. This count is used to ensure we don't go into
             * a busy loop of continuous errors.
             */
            ap_log_error(APLOG_MARK, APLOG_INFO, apr_get_netos_error(), ap_server_conf, 
                         "select failed with error %d", apr_get_netos_error());
            count_select_errors++;
            if (count_select_errors > MAX_SELECT_ERRORS) {
                shutdown_in_progress = 1;
                ap_log_error(APLOG_MARK, APLOG_ERR, apr_get_netos_error(), ap_server_conf,
                             "Too many errors in select loop. Child process exiting.");
                break;
            }
	} else {
	    ap_listen_rec *lr;

	    lr = find_ready_listener(&main_fds);
	    if (lr != NULL) {
                /* fetch the native socket descriptor */
                apr_os_sock_get(&nsd, lr->sd);
	    }