very quick hack to httpd to show hook usage using APR_HOOK_PROBE_foo macros

   24330 -> create_connection
   24330   -> core.c
   24330   <- core.c
   24330 <- create_connection
   24330 -> pre_connection
   24330   -> mod_reqtimeout.c
   24330   <- mod_reqtimeout.c
   24330   -> core.c
   24330   <- core.c
   24330 <- pre_connection
   24330 -> process_connection
   24330   -> mod_echo.c
   24330   <- mod_echo.c
   24330   -> http_core.c
   24330 -> create_request
   24330   -> core.c
   24330   <- core.c
   24330   -> http_core.c
   24330   <- http_core.c
   24330 <- create_request
   24330 -> post_read_request
   24330   -> mod_headers.c
   24330   <- mod_headers.c
   24330   -> mod_proxy.c
   24330   <- mod_proxy.c
   24330   -> mod_auth_digest.c
   24330   <- mod_auth_digest.c
   24330   -> mod_reqtimeout.c
   24330   <- mod_reqtimeout.c
   24330   -> mod_setenvif.c
   24330   <- mod_setenvif.c
   24330 <- post_read_request
   24330 -> quick_handler
   24330   -> mod_cache.c
   24330   <- mod_cache.c
   24330   -> mod_backdoor.c
   24330   <- mod_backdoor.c
   24330 <- quick_handler
   24330 -> translate_name
   24330   -> mod_rewrite.c
   24330   <- mod_rewrite.c
   24330   -> mod_proxy.c
   24330   <- mod_proxy.c
   24330   -> mod_alias.c
   24330   <- mod_alias.c
   24330   -> mod_userdir.c
   24330   <- mod_userdir.c
   24330   -> mod_vhost_alias.c
   24330   <- mod_vhost_alias.c
   24330   -> core.c
   24330   <- core.c
   24330 <- translate_name
   24330 -> map_to_storage
   24330   -> mod_proxy.c
   24330   <- mod_proxy.c
   24330   -> http_core.c
   24330   <- http_core.c
   24330   -> http_core.c
   24330   <- http_core.c
   24330   -> core.c
   24330   <- core.c
   24330 <- map_to_storage
   24330 -> header_parser
   24330   -> mod_setenvif.c
   24330   <- mod_setenvif.c
   24330 <- header_parser
   24330 -> access_checker
   24330   -> mod_access_compat.c
   24330   <- mod_access_compat.c
   24330   -> mod_fcgid.c
   24330   <- mod_fcgid.c
   24330 <- access_checker
   24330 -> check_user_id
   24330   -> mod_auth_basic.c
   24330   <- mod_auth_basic.c
   24330   -> mod_auth_form.c
   24330   <- mod_auth_form.c
   24330   -> mod_auth_digest.c
   24330   <- mod_auth_digest.c
   24330   -> mod_fcgid.c
   24330   <- mod_fcgid.c
   24330   -> mod_authn_core.c
   24330   <- mod_authn_core.c
   24330 <- check_user_id
   24330 -> auth_checker
   24330   -> mod_fcgid.c
   24330   <- mod_fcgid.c
   24330   -> mod_authz_core.c
[Mon Dec 14 14:58:39 2009] [debug] mod_authz_core.c(717): [client 127.0.0.1] authorization result of Require all granted: granted
   24330 -> error_log
   24330 <- error_log
[Mon Dec 14 14:58:39 2009] [debug] mod_authz_core.c(717): [client 127.0.0.1] authorization result of <RequireAny>: granted
   24330 -> error_log
   24330 <- error_log
   24330   <- mod_authz_core.c
   24330 <- auth_checker
   24330 -> type_checker
   24330   -> mod_negotiation.c
   24330   <- mod_negotiation.c
   24330   -> mod_mime.c
   24330   <- mod_mime.c
   24330   -> core.c
   24330   <- core.c
   24330 <- type_checker
   24330 -> fixups
   24330   -> core.c
   24330   <- core.c
   24330   -> mod_proxy.c
   24330   <- mod_proxy.c
   24330   -> mod_rewrite.c
   24330   <- mod_rewrite.c
   24330   -> mod_auth_digest.c
   24330   <- mod_auth_digest.c
   24330   -> mod_env.c
   24330   <- mod_env.c
   24330   -> mod_dav.c
   24330   <- mod_dav.c
   24330   -> mod_negotiation.c
   24330   <- mod_negotiation.c
   24330   -> mod_alias.c
   24330   <- mod_alias.c
   24330   -> mod_include.c
   24330   <- mod_include.c
   24330   -> mod_headers.c
   24330   <- mod_headers.c
   24330   -> mod_dir.c
   24330   <- mod_dir.c
   24330   -> mod_dir.c
   24330   <- mod_dir.c
   24330   -> mod_rewrite.c
   24330   <- mod_rewrite.c
   24330 <- fixups
   24330 -> insert_filter
   24330   -> core.c
   24330   <- core.c
   24330   -> mod_case_filter.c
   24330   <- mod_case_filter.c
   24330   -> mod_case_filter_in.c
   24330   <- mod_case_filter_in.c
   24330   -> mod_filter.c
   24330   <- mod_filter.c
   24330   -> mod_expires.c
   24330   <- mod_expires.c
   24330   -> mod_request.c
   24330   <- mod_request.c
   24330   -> mod_headers.c
   24330   <- mod_headers.c
   24330 <- insert_filter
   24330 -> handler
   24330   -> mod_cache.c
   24330   <- mod_cache.c
   24330   -> mod_heartmonitor.c
   24330   <- mod_heartmonitor.c
   24330   -> mod_proxy.c
   24330   <- mod_proxy.c
   24330   -> mod_proxy_balancer.c
   24330   <- mod_proxy_balancer.c
   24330   -> mod_auth_form.c
   24330   <- mod_auth_form.c
   24330   -> mod_auth_form.c
   24330   <- mod_auth_form.c
   24330   -> mod_auth_form.c
   24330   <- mod_auth_form.c
   24330   -> util_ldap.c
   24330   <- util_ldap.c
   24330   -> mod_dav.c
   24330   <- mod_dav.c
   24330   -> mod_status.c
   24330   <- mod_status.c
   24330   -> mod_autoindex.c
   24330   <- mod_autoindex.c
   24330   -> mod_asis.c
   24330   <- mod_asis.c
   24330   -> mod_info.c
   24330   <- mod_info.c
   24330   -> mod_cgid.c
   24330   <- mod_cgid.c
   24330   -> mod_negotiation.c
   24330   <- mod_negotiation.c
   24330   -> mod_imagemap.c
   24330   <- mod_imagemap.c
   24330   -> mod_rewrite.c
   24330   <- mod_rewrite.c
   24330   -> mod_fcgid.c
   24330   <- mod_fcgid.c
   24330   -> mod_actions.c
   24330   <- mod_actions.c
   24330   -> mod_dialup.c
   24330   <- mod_dialup.c
   24330   -> core.c
[Mon Dec 14 14:58:39 2009] [error] [client 127.0.0.1] File does not exist: /home/trawick/inst/23/htdocs/foo
   24330 -> error_log
   24330 <- error_log
   24330   <- core.c
   24330 <- handler
   24330 -> insert_error_filter
   24330   -> mod_expires.c
   24330   <- mod_expires.c
   24330   -> mod_headers.c
   24330   <- mod_headers.c
   24330 <- insert_error_filter
   24330 -> mpm_query
   24330   -> mod_backdoor.c
   24330   <- mod_backdoor.c
   24330   -> worker.c
   24330   <- worker.c
   24330 <- mpm_query
   24330 -> log_transaction
   24330   -> mod_reqtimeout.c
   24330   <- mod_reqtimeout.c
   24330   -> mod_log_config.c
   24330   <- mod_log_config.c
   24330 <- log_transaction






Index: server/log.c
===================================================================
--- server/log.c	(revision 890428)
+++ server/log.c	(working copy)
@@ -1127,6 +1127,40 @@
     apr_pool_cleanup_run(pl->p, pl, piped_log_cleanup);
 }
 
+void *ap_hook_probe_entry(const char *name)
+{
+    if (getenv("HOOK_TRACE")) {
+        fprintf(stderr, "% 8" APR_PID_T_FMT " -> %s\n", getpid(), name);
+        fflush(stderr);
+        return (void *)1;
+    }
+    return NULL;
+}
+
+void ap_hook_probe_return(void *ud, const char *name)
+{
+    if (ud) {
+        fprintf(stderr, "% 8" APR_PID_T_FMT " <- %s\n", getpid(), name);
+        fflush(stderr);
+    }
+}
+
+void ap_hook_probe_invoke(void *ud, const char *name, const char *src)
+{
+    if (ud) {
+        fprintf(stderr, "% 8" APR_PID_T_FMT "   -> %s\n", getpid(), src);
+        fflush(stderr);
+    }
+}
+
+void ap_hook_probe_complete(void *ud, const char *name, const char *src)
+{
+    if (ud) {
+        fprintf(stderr, "% 8" APR_PID_T_FMT "   <- %s\n", getpid(), src);
+        fflush(stderr);
+    }
+}
+
 AP_IMPLEMENT_HOOK_VOID(error_log,
                        (const char *file, int line, int level,
                         apr_status_t status, const server_rec *s,
Index: include/http_connection.h
===================================================================
--- include/http_connection.h	(revision 890428)
+++ include/http_connection.h	(working copy)
@@ -26,7 +26,7 @@
 #ifndef APACHE_HTTP_CONNECTION_H
 #define APACHE_HTTP_CONNECTION_H
 
-#include "apr_hooks.h"
+#include "ap_hooks.h"
 #include "apr_network_io.h"
 #include "apr_buckets.h"
 
Index: include/http_protocol.h
===================================================================
--- include/http_protocol.h	(revision 890428)
+++ include/http_protocol.h	(working copy)
@@ -27,7 +27,7 @@
 #define APACHE_HTTP_PROTOCOL_H
 
 #include "httpd.h"
-#include "apr_hooks.h"
+#include "ap_hooks.h"
 #include "apr_portable.h"
 #include "apr_mmap.h"
 #include "apr_buckets.h"
Index: include/ap_hooks.h
===================================================================
--- include/ap_hooks.h	(revision 0)
+++ include/ap_hooks.h	(revision 0)
@@ -0,0 +1,32 @@
+#ifndef AP_HOOKS_H
+#define AP_HOOKS_H
+
+#define APR_HOOK_PROBES_ENABLED
+
+#ifdef APR_HOOK_PROBE_ENTRY  /* apr_hooks.h included before this? */
+#undef APR_HOOK_PROBE_ENTRY
+#undef APR_HOOK_PROBE_RETURN
+#undef APR_HOOK_PROBE_INVOKE
+#undef APR_HOOK_PROBE_COMPLETE
+#endif
+
+#define APR_HOOK_PROBE_ENTRY(ud,ns,name) \
+  ud = ap_hook_probe_entry(#name)
+
+#define APR_HOOK_PROBE_RETURN(ud,ns,name,rv) \
+  ap_hook_probe_return(ud, #name)
+
+#define APR_HOOK_PROBE_INVOKE(ud,ns,name,src) \
+  ap_hook_probe_invoke(ud, #name, src)
+
+#define APR_HOOK_PROBE_COMPLETE(ud,ns,name,src,rv) \
+  ap_hook_probe_complete(ud, #name, src)
+
+#include "apr_hooks.h"
+
+void *ap_hook_probe_entry(const char *name);
+void ap_hook_probe_return(void *ud, const char *name);
+void ap_hook_probe_invoke(void *ud, const char *name, const char *src);
+void ap_hook_probe_complete(void *ud, const char *name, const char *src);
+
+#endif
Index: include/http_config.h
===================================================================
--- include/http_config.h	(revision 890428)
+++ include/http_config.h	(working copy)
@@ -26,7 +26,7 @@
 #ifndef APACHE_HTTP_CONFIG_H
 #define APACHE_HTTP_CONFIG_H
 
-#include "apr_hooks.h"
+#include "ap_hooks.h"
 #include "util_cfgtree.h"
 
 #ifdef __cplusplus
Index: include/scoreboard.h
===================================================================
--- include/scoreboard.h	(revision 890428)
+++ include/scoreboard.h	(working copy)
@@ -32,7 +32,7 @@
 #endif
 
 #include "ap_config.h"
-#include "apr_hooks.h"
+#include "ap_hooks.h"
 #include "apr_thread_proc.h"
 #include "apr_portable.h"
 #include "apr_shm.h"
Index: include/ap_config.h
===================================================================
--- include/ap_config.h	(revision 890428)
+++ include/ap_config.h	(working copy)
@@ -23,7 +23,7 @@
 #define AP_CONFIG_H
 
 #include "apr.h"
-#include "apr_hooks.h"
+#include "ap_hooks.h"
 #include "apr_optional_hooks.h"
 
 /* Although this file doesn't declare any hooks, declare the hook group here */
Index: include/http_request.h
===================================================================
--- include/http_request.h	(revision 890428)
+++ include/http_request.h	(working copy)
@@ -47,7 +47,7 @@
 #ifndef APACHE_HTTP_REQUEST_H
 #define APACHE_HTTP_REQUEST_H
 
-#include "apr_hooks.h"
+#include "ap_hooks.h"
 #include "apr_optional.h"
 #include "util_filter.h"