* Move the Example modules to the newly created examples subdirectory

* Hopefully correctly fudge the NWGNU make files
* Add mod_example_ipc (without NWGNU stuff or dsp)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@596093 13f79535-47bb-0310-9956-ffa450edef68

modules/README

@@ -18,6 +18,10 @@ dav/
 
 echo/
 
+examples/
+  This directory contains some sample code that should help you on your
+  way to develop your own Apache modules.  
+
 experimental/
   In this directory we've placed some modules which we think
   provide some pretty interesting functionality, but which

modules/examples/Makefile.in

@@ -0,0 +1,3 @@
+# a modules Makefile has no explicit targets -- they will be defined by
+# whatever modules are enabled. just grab special.mk to deal with this.
+include $(top_srcdir)/build/special.mk

modules/examples/NWGNUhooks

@@ -102,19 +102,19 @@ endif
 # This is used by the link 'name' directive to name the nlm.  If left blank
 # TARGET_nlm (see below) will be used.
 #
-NLM_NAME	= example
+NLM_NAME	= example_hooks
 
 #
 # This is used by the link '-desc ' directive.
 # If left blank, NLM_NAME will be used.
 #
-NLM_DESCRIPTION	= Apache $(VERSION_STR) Example Module
+NLM_DESCRIPTION	= Apache $(VERSION_STR) Example Hook Callback Handler Module
 
 #
 # This is used by the '-threadname' directive.  If left blank,
 # NLM_NAME Thread will be used.
 #
-NLM_THREAD_NAME	= Example Module
+NLM_THREAD_NAME	= Example Hook Callback Handler Module
 
 #
 # If this is specified, it will override VERSION value in
@@ -159,7 +159,7 @@ XDCDATA		=
 # If there is an NLM target, put it here
 #
 TARGET_nlm = \
-	$(OBJDIR)/example.nlm \
+	$(OBJDIR)/example_hooks.nlm \
 	$(EOLIST)
 
 #
@@ -173,7 +173,7 @@ TARGET_lib = \
 # Paths must all use the '/' character
 #
 FILES_nlm_objs = \
-	$(OBJDIR)/mod_example.o \
+	$(OBJDIR)/mod_example_hooks.o \
 	$(EOLIST)
 
 #

modules/examples/NWGNUmakefile

@@ -0,0 +1,255 @@
+#
+# Declare the sub-directories to be built here
+#
+
+SUBDIRS = \
+	$(EOLIST)
+
+#
+# Get the 'head' of the build environment.  This includes default targets and
+# paths to tools
+#
+
+include $(AP_WORK)\build\NWGNUhead.inc
+
+#
+# build this level's files
+
+#
+# Make sure all needed macro's are defined
+#
+
+#
+# These directories will be at the beginning of the include list, followed by
+# INCDIRS
+#
+XINCDIRS	+= \
+			$(EOLIST)
+
+#
+# These flags will come after CFLAGS
+#
+XCFLAGS		+= \
+			$(EOLIST)
+
+#
+# These defines will come after DEFINES
+#
+XDEFINES	+= \
+			$(EOLIST)
+
+#
+# These flags will be added to the link.opt file
+#
+XLFLAGS		+= \
+			$(EOLIST)
+
+#
+# These values will be appended to the correct variables based on the value of
+# RELEASE
+#
+ifeq "$(RELEASE)" "debug"
+XINCDIRS	+= \
+			$(EOLIST)
+
+XCFLAGS		+= \
+			$(EOLIST)
+
+XDEFINES	+= \
+			$(EOLIST)
+
+XLFLAGS		+= \
+			$(EOLIST)
+endif
+
+ifeq "$(RELEASE)" "noopt"
+XINCDIRS	+= \
+			$(EOLIST)
+
+XCFLAGS		+= \
+			$(EOLIST)
+
+XDEFINES	+= \
+			$(EOLIST)
+
+XLFLAGS		+= \
+			$(EOLIST)
+endif
+
+ifeq "$(RELEASE)" "release"
+XINCDIRS	+= \
+			$(EOLIST)
+
+XCFLAGS		+= \
+			$(EOLIST)
+
+XDEFINES	+= \
+			$(EOLIST)
+
+XLFLAGS		+= \
+			$(EOLIST)
+endif
+
+#
+# These are used by the link target if an NLM is being generated
+# This is used by the link 'name' directive to name the nlm.  If left blank
+# TARGET_nlm (see below) will be used.
+#
+NLM_NAME	=
+
+#
+# This is used by the link '-desc ' directive.
+# If left blank, NLM_NAME will be used.
+#
+NLM_DESCRIPTION	=
+
+#
+# This is used by the '-threadname' directive.  If left blank,
+# NLM_NAME Thread will be used.
+#
+NLM_THREAD_NAME	=
+
+#
+# If this is specified, it will override VERSION value in
+# $(AP_WORK)\build\NWGNUenvironment.inc
+#
+NLM_VERSION	=
+
+#
+# If this is specified, it will override the default of 64K
+#
+NLM_STACK_SIZE	=
+
+
+#
+# If this is specified it will be used by the link '-entry' directive
+#
+NLM_ENTRY_SYM	=
+
+#
+# If this is specified it will be used by the link '-exit' directive
+#
+NLM_EXIT_SYM	=
+
+#
+# If this is specified it will be used by the link '-check' directive
+#
+NLM_CHECK_SYM	=
+
+#
+# If these are specified it will be used by the link '-flags' directive
+#
+NLM_FLAGS	=
+
+#
+# If this is specified it will be linked in with the XDCData option in the def
+# file instead of the default of $(NWOS)/apache.xdc.  XDCData can be disabled
+# by setting APACHE_UNIPROC in the environment
+#
+XDCDATA		=
+
+#
+# If there is an NLM target, put it here
+#
+# We are referencing example.nlm twice to get around a known issue with the
+# makefiles.  Normally if there is only one element to be built within a
+# directory, the makefile for the single element would be called NWGNUmakefile.
+# But if there are multiples, the parent NWGNUmakefile must reference more
+# than one submakefile. Because the experimental directory might vary in the
+# number of submakefiles, but for the moment only contains one, we reference
+# it twice to allow it parent NWGNUmakefile to work properly.  If another
+# submakefile is added, the extra reference to example.nlm should be removed.
+TARGET_nlm = \
+	$(OBJDIR)/example.nlm \
+	$(OBJDIR)/case_flt.nlm \
+	$(OBJDIR)/case_flt_in.nlm \
+	$(EOLIST)
+
+#
+# If there is an LIB target, put it here
+#
+TARGET_lib = \
+	$(EOLIST)
+
+#
+# These are the OBJ files needed to create the NLM target above.
+# Paths must all use the '/' character
+#
+FILES_nlm_objs = \
+	$(EOLIST)
+
+#
+# These are the LIB files needed to create the NLM target above.
+# These will be added as a library command in the link.opt file.
+#
+FILES_nlm_libs = \
+	$(EOLIST)
+
+#
+# These are the modules that the above NLM target depends on to load.
+# These will be added as a module command in the link.opt file.
+#
+FILES_nlm_modules = \
+	$(EOLIST)
+
+#
+# If the nlm has a msg file, put it's path here
+#
+FILE_nlm_msg =
+
+#
+# If the nlm has a hlp file put it's path here
+#
+FILE_nlm_hlp =
+
+#
+# If this is specified, it will override $(NWOS)\copyright.txt.
+#
+FILE_nlm_copyright =
+
+#
+# Any additional imports go here
+#
+FILES_nlm_Ximports = \
+	$(EOLIST)
+
+#
+# Any symbols exported to here
+#
+FILES_nlm_exports = \
+	$(EOLIST)
+
+#
+# These are the OBJ files needed to create the LIB target above.
+# Paths must all use the '/' character
+#
+FILES_lib_objs = \
+	$(EOLIST)
+
+#
+# implement targets and dependancies (leave this section alone)
+#
+
+libs :: $(OBJDIR) $(TARGET_lib)
+
+nlms :: libs $(TARGET_nlm)
+
+#
+# Updated this target to create necessary directories and copy files to the
+# correct place.  (See $(AP_WORK)\build\NWGNUhead.inc for examples)
+#
+install :: nlms FORCE
+	copy $(OBJDIR)\*.nlm $(INSTALL)\$(BASEDIR)\modules\*.*
+
+#
+# Any specialized rules here
+#
+
+#
+# Include the 'tail' makefile that has targets that depend on variables defined
+# in this makefile
+#
+
+include $(AP_WORK)\build\NWGNUtail.inc
+
+

modules/examples/config.m4

@@ -0,0 +1,9 @@
+
+APACHE_MODPATH_INIT(examples)
+
+APACHE_MODULE(example_hooks, Example hook callback handler module, , , no)
+APACHE_MODULE(case_filter, Example uppercase conversion filter, , , no)
+APACHE_MODULE(case_filter_in, Example uppercase conversion input filter, , , no)
+APACHE_MODULE(example_ipc, Example of shared memory and mutex usage, , , no)
+
+APACHE_MODPATH_FINISH

modules/examples/mod_example_hooks.c

@@ -25,16 +25,17 @@
  * this module, but which may have counterparts in *real* modules, are
  * prefixed with 'x_' instead of 'example_'.
  *
- * To use mod_example, configure the Apache build with --enable-example and 
+ * To use mod_example_hooks, configure the Apache build with
- * compile.  Set up a <Location> block in your configuration file like so: 
+ * --enable-example and compile.  Set up a <Location> block in your
+ * configuration file like so: 
  * 
  * <Location /example>
- *    SetHandler example-handler
+ *    SetHandler example-hooks-handler
  * </Location> 
  * 
  * When you look at that location on your server, you will see a backtrace of 
  * the callbacks that have been invoked up to that point.  See the ErrorLog for 
- * more information on code paths that  touch mod_example. 
+ * more information on code paths that  touch mod_example_hooks. 
  *
  * IMPORTANT NOTES
  * ===============
@@ -44,7 +45,7 @@
  * request processing, and produces copious amounts of logging data.  This will 
  * negatively affect server performance. 
  * 
- * Do NOT use mod_example as the basis for your own code.  This module
+ * Do NOT use mod_example_hooks as the basis for your own code.  This module
  * implements every callback hook offered by the Apache core, and your
  * module will almost certainly not have to implement this much.  If you
  * want a simple module skeleton to start development, use apxs -g. 
@@ -128,7 +129,7 @@ static const char *trace = NULL;
  * Declare ourselves so the configuration routines can find and know us.
  * We'll fill it in at the end of the module.
  */
-module AP_MODULE_DECLARE_DATA example_module;
+module AP_MODULE_DECLARE_DATA example_hooks_module;
 
 /*--------------------------------------------------------------------------*/
 /*                                                                          */
@@ -279,7 +280,7 @@ module AP_MODULE_DECLARE_DATA example_module;
  */
 static x_cfg *our_dconfig(const request_rec *r)
 {
-    return (x_cfg *) ap_get_module_config(r->per_dir_config, &example_module);
+    return (x_cfg *) ap_get_module_config(r->per_dir_config, &example_hooks_module);
 }
 
 /* 
@@ -293,7 +294,7 @@ static x_cfg *our_dconfig(const request_rec *r)
  */
 static x_cfg *our_sconfig(const server_rec *s)
 {
-    return (x_cfg *) ap_get_module_config(s->module_config, &example_module);
+    return (x_cfg *) ap_get_module_config(s->module_config, &example_hooks_module);
 }
 
 /*
@@ -301,7 +302,7 @@ static x_cfg *our_sconfig(const server_rec *s)
  */
 static x_cfg *our_rconfig(const request_rec *r)
 {
-    return (x_cfg *) ap_get_module_config(r->request_config, &example_module);
+    return (x_cfg *) ap_get_module_config(r->request_config, &example_hooks_module);
 }
 #endif /* if 0 */
 
@@ -310,7 +311,7 @@ static x_cfg *our_rconfig(const request_rec *r)
  */
 static x_cfg *our_cconfig(const conn_rec *c)
 {
-    return (x_cfg *) ap_get_module_config(c->conn_config, &example_module);
+    return (x_cfg *) ap_get_module_config(c->conn_config, &example_hooks_module);
 }
 
 /*
@@ -386,7 +387,7 @@ static void trace_startup(apr_pool_t *p, server_rec *s, x_cfg *mconfig,
  * This utility route traces the hooks called as a request is handled. 
  * It takes the current request as argument 
  */
-#define TRACE_NOTE "example-trace"
+#define TRACE_NOTE "example-hooks-trace"
  
 static void trace_request(const request_rec *r, const char *note)
 {
@@ -432,7 +433,7 @@ static void trace_request(const request_rec *r, const char *note)
  * the connection and its pool to itself entirely, and in
  * multi-threaded mode each connection will have its own pool.
  */
-#define CONN_NOTE "example-connection"
+#define CONN_NOTE "example-hooks-connection"
 
 static void trace_connection(conn_rec *c, const char *note) 
 {
@@ -983,7 +984,7 @@ static int x_handler(request_rec *r)
     trace_request(r, note);
 
     /* If it's not for us, get out as soon as possible. */
-    if (strcmp(r->handler, "example-handler")) {
+    if (strcmp(r->handler, "example-hooks-handler")) {
         return DECLINED;
     }
 
@@ -1007,11 +1008,11 @@ static int x_handler(request_rec *r)
     ap_rputs(DOCTYPE_HTML_3_2, r);
     ap_rputs("<HTML>\n", r);
     ap_rputs(" <HEAD>\n", r);
-    ap_rputs("  <TITLE>mod_example Module Content-Handler Output\n", r);
+    ap_rputs("  <TITLE>mod_example_hooks Module Content-Handler Output\n", r);
     ap_rputs("  </TITLE>\n", r);
     ap_rputs(" </HEAD>\n", r);
     ap_rputs(" <BODY>\n", r);
-    ap_rputs("  <H1><SAMP>mod_example</SAMP> Module Content-Handler Output\n", r);
+    ap_rputs("  <H1><SAMP>mod_example_hooks</SAMP> Module Content-Handler Output\n", r);
     ap_rputs("  </H1>\n", r);
     ap_rputs("  <P>\n", r);
     ap_rprintf(r, "  Apache HTTP Server version: \"%s\"\n",
@@ -1505,7 +1506,7 @@ static const command_rec x_cmds[] =
  * Module definition for configuration.  If a particular callback is not
  * needed, replace its routine name below with the word NULL.
  */
-module AP_MODULE_DECLARE_DATA example_module =
+module AP_MODULE_DECLARE_DATA example_hooks_module =
 {
     STANDARD20_MODULE_STUFF,
     x_create_dir_config,    /* per-directory config creator */

modules/examples/mod_example_ipc.c

@@ -0,0 +1,385 @@
+/* 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.
+ */
+
+/* 
+ *  mod_example_ipc -- Apache sample module 
+ * 
+ * This module illustrates the use in an Apache 2.x module of the Interprocess
+ * Communications routines that come with APR. It is example code, and not meant 
+ * to be used in a production server. 
+ *
+ * To play with this sample module first compile it into a DSO file and install
+ * it into Apache's modules directory by running:
+ *
+ *    $ /path/to/apache2/bin/apxs -c -i mod_example_ipc.c
+ *
+ * Then activate it in Apache's httpd.conf file for instance for the URL
+ * /example_ipc in as follows:
+ *
+ *    #   httpd.conf
+ *    LoadModule example_ipc_module modules/mod_example_ipc.so
+ *    <Location /example_ipc>
+ *    SetHandler example_ipc
+ *    </Location>
+ *
+ * Then restart Apache via
+ *
+ *    $ /path/to/apache2/bin/apachectl restart
+ *
+ * The module allocates a counter in shared memory, which is incremented by the
+ * request handler under a mutex. After installation, activate the handler by
+ * hitting the URL configured above with ab at various concurrency levels to see
+ * how mutex contention affects server performance. 
+ */ 
+
+#include "apr.h"
+#include "apr_strings.h"
+
+#include "httpd.h"
+#include "http_config.h"
+#include "http_log.h"
+#include "http_protocol.h"
+#include "ap_config.h"
+
+#if !defined(OS2) && !defined(WIN32) && !defined(BEOS) && !defined(NETWARE)
+#include "unixd.h"
+#define MOD_EXIPC_SET_MUTEX_PERMS /* XXX Apache should define something */
+#endif
+
+#if APR_HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#if APR_HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#define HTML_HEADER "<html>\n<head>\n<title>Mod_example_IPC Status Page " \
+                    "</title>\n</head>\n<body>\n<h1>Mod_example_IPC Status</h1>\n"
+#define HTML_FOOTER "</body>\n</html>\n"
+
+/* Number of microseconds to camp out on the mutex */
+#define CAMPOUT 10
+/* Maximum number of times we camp out before giving up */
+#define MAXCAMP 10
+/* Number of microseconds the handler sits on the lock once acquired. */
+#define SLEEPYTIME 1000
+
+apr_shm_t *exipc_shm; /* Pointer to shared memory block */
+char *shmfilename; /* Shared memory file name, used on some systems */
+apr_global_mutex_t *exipc_mutex; /* Lock around shared memory segment access */
+char *mutexfilename; /* Lock file name, used on some systems */
+
+/* Data structure for shared memory block */
+typedef struct exipc_data {
+    apr_uint64_t counter; 
+    /* More fields if necessary */
+} exipc_data;
+
+/* 
+ * Clean up the shared memory block. This function is registered as 
+ * cleanup function for the configuration pool, which gets called
+ * on restarts. It assures that the new children will not talk to a stale 
+ * shared memory segment. 
+ */
+static apr_status_t shm_cleanup_wrapper(void *unused) {
+    if (exipc_shm)
+        return apr_shm_destroy(exipc_shm);
+    return OK;
+}
+
+
+/* 
+ * This routine is called in the parent, so we'll set up the shared
+ * memory segment and mutex here. 
+ */
+
+static int exipc_post_config(apr_pool_t *pconf, apr_pool_t *plog, 
+                             apr_pool_t *ptemp, server_rec *s)
+{
+    void *data; /* These two help ensure that we only init once. */
+    const char *userdata_key;
+    apr_status_t rs;
+    exipc_data *base;
+    const char *tempdir; 
+
+
+    /* 
+     * The following checks if this routine has been called before. 
+     * This is necessary because the parent process gets initialized
+     * a couple of times as the server starts up, and we don't want 
+     * to create any more mutexes and shared memory segments than
+     * we're actually going to use. 
+     * 
+     * The key needs to be unique for the entire web server, so put
+     * the module name in it.
+     */ 
+    userdata_key = "example_ipc_init_module";
+    apr_pool_userdata_get(&data, userdata_key, s->process->pool);
+    if (!data) {
+        /* 
+         * If no data was found for our key, this must be the first
+         * time the module is initialized. Put some data under that
+         * key and return.
+         */
+        apr_pool_userdata_set((const void *) 1, userdata_key, 
+                              apr_pool_cleanup_null, s->process->pool);
+        return OK;
+    } /* Kilroy was here */
+
+    /* 
+     * Both the shared memory and mutex allocation routines take a
+     * file name. Depending on system-specific implementation of these
+     * routines, that file may or may not actually be created. We'd
+     * like to store those files in the operating system's designated
+     * temporary directory, which APR can point us to.
+     */
+    rs = apr_temp_dir_get(&tempdir, pconf);
+    if (APR_SUCCESS != rs) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rs, s, 
+                     "Failed to find temporary directory");
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    /* Create the shared memory segment */
+
+    /* 
+     * Create a unique filename using our pid. This information is 
+     * stashed in the global variable so the children inherit it.
+     */
+    shmfilename = apr_psprintf(pconf, "%s/httpd_shm.%ld", tempdir, 
+                               (long int)getpid());
+
+    /* Now create that segment */
+    rs = apr_shm_create(&exipc_shm, sizeof(exipc_data), 
+                        (const char *) shmfilename, pconf);
+    if (APR_SUCCESS != rs) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rs, s, 
+                     "Failed to create shared memory segment on file %s", 
+                     shmfilename);
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    /* Created it, now let's zero it out */
+    base = (exipc_data *)apr_shm_baseaddr_get(exipc_shm);
+    base->counter = 0;
+
+    /* Create global mutex */
+
+    /* 
+     * Create another unique filename to lock upon. Note that
+     * depending on OS and locking mechanism of choice, the file
+     * may or may not be actually created. 
+     */
+    mutexfilename = apr_psprintf(pconf, "%s/httpd_mutex.%ld", tempdir,
+                                 (long int) getpid());
+  
+    rs = apr_global_mutex_create(&exipc_mutex, (const char *) mutexfilename, 
+                                 APR_LOCK_DEFAULT, pconf);
+    if (APR_SUCCESS != rs) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, rs, s, 
+                     "Failed to create mutex on file %s", 
+                     mutexfilename);
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+
+    /* 
+     * After the mutex is created, its permissions need to be adjusted
+     * on unix platforms so that the child processe can acquire
+     * it. This call takes care of that. The preprocessor define was
+     * set up early in this source file since Apache doesn't provide
+     * it.
+     */
+#ifdef MOD_EXIPC_SET_MUTEX_PERMS
+    rs = unixd_set_global_mutex_perms(exipc_mutex);
+    if (APR_SUCCESS != rs) {
+        ap_log_error(APLOG_MARK, APLOG_CRIT, rs, s, 
+                     "Parent could not set permissions on Example IPC "
+                     "mutex: check User and Group directives");
+        return HTTP_INTERNAL_SERVER_ERROR;
+    }
+#endif /* MOD_EXIPC_SET_MUTEX_PERMS */
+
+    /* 
+     * Destroy the shm segment when the configuration pool gets destroyed. This
+     * happens on server restarts. The parent will then (above) allocate a new
+     * shm segment that the new children will bind to. 
+     */
+    apr_pool_cleanup_register(pconf, NULL, shm_cleanup_wrapper, 
+                              apr_pool_cleanup_null);    
+    return OK;
+}
+
+/* 
+ * This routine gets called when a child inits. We use it to attach
+ * to the shared memory segment, and reinitialize the mutex.
+ */
+
+static void exipc_child_init(apr_pool_t *p, server_rec *s)
+{
+    apr_status_t rs;
+         
+    /* 
+     * Re-open the mutex for the child. Note we're reusing
+     * the mutex pointer global here. 
+     */
+    rs = apr_global_mutex_child_init(&exipc_mutex, 
+                                     (const char *) mutexfilename, 
+                                     p);
+    if (APR_SUCCESS != rs) {
+        ap_log_error(APLOG_MARK, APLOG_CRIT, rs, s, 
+                     "Failed to reopen mutex on file %s", 
+                     shmfilename);
+        /* There's really nothing else we can do here, since This
+         * routine doesn't return a status. If this ever goes wrong,
+         * it will turn Apache into a fork bomb. Let's hope it never
+         * will.
+         */
+        exit(1); /* Ugly, but what else? */
+    } 
+}
+
+/* The sample content handler */
+static int exipc_handler(request_rec *r)
+{
+    int gotlock = 0;
+    int camped;
+    apr_time_t startcamp;
+    apr_int64_t timecamped;
+    apr_status_t rs; 
+    exipc_data *base;
+    
+    if (strcmp(r->handler, "example_ipc")) {
+        return DECLINED;
+    }
+    
+    /* 
+     * The main function of the handler, aside from sending the 
+     * status page to the client, is to increment the counter in 
+     * the shared memory segment. This action needs to be mutexed 
+     * out using the global mutex. 
+     */
+     
+    /* 
+     * First, acquire the lock. This code is a lot more involved than
+     * it usually needs to be, because the process based trylock
+     * routine is not implemented on unix platforms. I left it in to
+     * show how it would work if trylock worked, and for situations
+     * and platforms where trylock works.
+     */
+    for (camped = 0, timecamped = 0; camped < MAXCAMP; camped++) {
+        rs = apr_global_mutex_trylock(exipc_mutex); 
+        if (APR_STATUS_IS_EBUSY(rs)) {
+            apr_sleep(CAMPOUT);
+        } else if (APR_SUCCESS == rs) {
+            gotlock = 1; 
+            break; /* Get out of the loop */
+        } else if (APR_STATUS_IS_ENOTIMPL(rs)) {
+            /* If it's not implemented, just hang in the mutex. */
+            startcamp = apr_time_now();
+            rs = apr_global_mutex_lock(exipc_mutex);
+            timecamped = (apr_int64_t) (apr_time_now() - startcamp);
+            if (APR_SUCCESS == rs) {
+                gotlock = 1;
+                break; /* Out of the loop */
+            } else {
+                /* Some error, log and bail */
+                ap_log_error(APLOG_MARK, APLOG_ERR, rs, r->server, 
+                             "Child %ld failed to acquire lock", 
+                             (long int)getpid());
+                break; /* Out of the loop without having the lock */
+            }                
+        } else {
+            /* Some other error, log and bail */
+            ap_log_error(APLOG_MARK, APLOG_ERR, rs, r->server, 
+                         "Child %ld failed to try and acquire lock", 
+                         (long int)getpid());
+            break; /* Out of the loop without having the lock */
+            
+        }
+        /* 
+         * The only way to get to this point is if the trylock worked
+         * and returned BUSY. So, bump the time and try again
+         */
+        timecamped += CAMPOUT;
+        ap_log_error(APLOG_MARK, APLOG_NOERRNO | APLOG_NOTICE, 
+                     0, r->server, "Child %ld camping out on mutex for %d " 
+                     "microseconds",
+                     (long int) getpid(), timecamped);
+    } /* Lock acquisition loop */
+    
+    /* Sleep for a millisecond to make it a little harder for
+     * httpd children to acquire the lock. 
+     */
+    apr_sleep(SLEEPYTIME);
+    
+    r->content_type = "text/html";      
+
+    if (!r->header_only) {
+        ap_rputs(HTML_HEADER, r);
+        if (gotlock) {
+            /* Increment the counter */
+            base = (exipc_data *)apr_shm_baseaddr_get(exipc_shm);
+            base->counter++;
+            /* Send a page with our pid and the new value of the counter. */
+            ap_rprintf(r, "<p>Lock acquired after %ld microseoncds.</p>\n", 
+                       (long int) timecamped); 
+            ap_rputs("<table border=\"1\">\n", r);
+            ap_rprintf(r, "<tr><td>Child pid:</td><td>%d</td></tr>\n", 
+                       (int) getpid());
+            ap_rprintf(r, "<tr><td>Counter:</td><td>%u</td></tr>\n", 
+                       (unsigned int)base->counter);
+            ap_rputs("</table>\n", r);
+        } else {
+            /* 
+             * Send a page saying that we couldn't get the lock. Don't say
+             * what the counter is, because without the lock the value could
+             * race. 
+             */
+            ap_rprintf(r, "<p>Child %d failed to acquire lock "
+                       "after camping out for %d microseconds.</p>\n", 
+                       (int) getpid(), (int) timecamped);
+        }
+        ap_rputs(HTML_FOOTER, r); 
+    } /* r->header_only */
+    
+    /* Release the lock */
+    if (gotlock)
+        rs = apr_global_mutex_unlock(exipc_mutex); 
+    /* Swallowing the result because what are we going to do with it at 
+     * this stage? 
+     */
+
+    return OK;
+}
+
+static void exipc_register_hooks(apr_pool_t *p)
+{
+    ap_hook_post_config(exipc_post_config, NULL, NULL, APR_HOOK_MIDDLE); 
+    ap_hook_child_init(exipc_child_init, NULL, NULL, APR_HOOK_MIDDLE); 
+    ap_hook_handler(exipc_handler, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+/* Dispatch list for API hooks */
+module AP_MODULE_DECLARE_DATA example_ipc_module = {
+    STANDARD20_MODULE_STUFF, 
+    NULL,                  /* create per-dir    config structures */
+    NULL,                  /* merge  per-dir    config structures */
+    NULL,                  /* create per-server config structures */
+    NULL,                  /* merge  per-server config structures */
+    NULL,                  /* table of config file commands       */
+    exipc_register_hooks   /* register hooks                      */
+};
+

modules/experimental/NWGNUmakefile

@@ -160,9 +160,6 @@ XDCDATA		=
 # it twice to allow it parent NWGNUmakefile to work properly.  If another
 # submakefile is added, the extra reference to example.nlm should be removed.
 TARGET_nlm = \
-	$(OBJDIR)/example.nlm \
-	$(OBJDIR)/case_flt.nlm \
-	$(OBJDIR)/case_flt_in.nlm \
 	$(OBJDIR)/substitute.nlm \
 	$(EOLIST)
 

modules/experimental/config.m4

@@ -1,9 +1,6 @@
 
 APACHE_MODPATH_INIT(experimental)
 
-APACHE_MODULE(example, example and demo module, , , no)
-APACHE_MODULE(case_filter, example uppercase conversion filter, , , no)
-APACHE_MODULE(case_filter_in, example uppercase conversion input filter, , , no)
 APACHE_MODULE(substitute, response content rewrite-like filtering, , , most)
 
 APACHE_MODPATH_FINISH