LP1204123 SIGUSR1 causes router unregister (Perl/C)

$ kill -s USR1 <listener_pid>

The listener process will unregister all router connections.  This
allows services to remove themselves from consideration for new
inbound requests while allowing their drone processes to complete
any currently running tasks.

Signed-off-by: Bill Erickson <berick@esilibrary.com>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>

diff --git a/src/libopensrf/osrf_prefork.c b/src/libopensrf/osrf_prefork.c
index 1293909..9e37f10 100644 (file)
--- a/src/libopensrf/osrf_prefork.c
+++ b/src/libopensrf/osrf_prefork.c
@@ -103,10 +103,15 @@ static prefork_child* prefork_child_init( prefork_simple* forker,
 static void prefork_child_wait( prefork_child* child );
 static void prefork_clear( prefork_simple* );
 static void prefork_child_free( prefork_simple* forker, prefork_child* );
-static void osrf_prefork_register_routers( const char* appname );
+static void osrf_prefork_register_routers( const char* appname, bool unregister );
 static void osrf_prefork_child_exit( prefork_child* );
 
 static void sigchld_handler( int sig );
+static void sigusr1_handler( int sig );
+
+/** Track the appname globally so we can refer back to it for 
+    router de-registration.  */
+static const char* service_name = NULL;
 
 /**
        @brief Spawn and manage a collection of drone processes for servicing requests.
@@ -121,6 +126,7 @@ int osrf_prefork_run( const char* appname ) {
        }
 
        set_proc_title( "OpenSRF Listener [%s]", appname );
+    service_name = appname;
 
        int maxr = 1000;
        int maxc = 10;
@@ -188,7 +194,9 @@ int osrf_prefork_run( const char* appname ) {
        prefork_launch_children( &forker );
 
        // Tell the router that you're open for business.
-       osrf_prefork_register_routers( appname );
+       osrf_prefork_register_routers( appname, false );
+
+    signal( SIGUSR1, sigusr1_handler );
 
        // Sit back and let the requests roll in
        osrfLogInfo( OSRF_LOG_MARK, "Launching osrf_forker for app %s", appname );
@@ -210,17 +218,30 @@ int osrf_prefork_run( const char* appname ) {
        Called only by the parent process.
 */
 static void osrf_prefork_send_router_registration(
-               const char* appname, const char* routerName, const char* routerDomain ) {
+               const char* appname, const char* routerName, 
+            const char* routerDomain, bool unregister ) {
+
        // Get a pointer to the global transport_client
        transport_client* client = osrfSystemGetTransportClient();
 
        // Construct the Jabber address of the router
        char* jid = va_list_to_string( "%s@%s/router", routerName, routerDomain );
-       osrfLogInfo( OSRF_LOG_MARK, "%s registering with router %s", appname, jid );
 
        // Create the registration message, and send it
-       transport_message* msg = message_init( "registering", NULL, NULL, jid, NULL );
-       message_set_router_info( msg, NULL, NULL, appname, "register", 0 );
+       transport_message* msg;
+    if (unregister) {
+
+           osrfLogInfo( OSRF_LOG_MARK, "%s un-registering with router %s", appname, jid );
+           msg = message_init( "unregistering", NULL, NULL, jid, NULL );
+           message_set_router_info( msg, NULL, NULL, appname, "unregister", 0 );
+
+    } else {
+
+           osrfLogInfo( OSRF_LOG_MARK, "%s registering with router %s", appname, jid );
+           msg = message_init( "registering", NULL, NULL, jid, NULL );
+           message_set_router_info( msg, NULL, NULL, appname, "register", 0 );
+    }
+
        client_send_message( client, msg );
 
        // Clean up
@@ -241,7 +262,8 @@ static void osrf_prefork_send_router_registration(
 
        Called only by the parent process.
 */
-static void osrf_prefork_parse_router_chunk( const char* appname, const jsonObject* routerChunk ) {
+static void osrf_prefork_parse_router_chunk( 
+    const char* appname, const jsonObject* routerChunk, bool unregister ) {
 
        const char* routerName = jsonObjectGetString( jsonObjectGetKeyConst( routerChunk, "name" ));
        const char* domain = jsonObjectGetString( jsonObjectGetKeyConst( routerChunk, "domain" ));
@@ -261,19 +283,19 @@ static void osrf_prefork_parse_router_chunk( const char* appname, const jsonObje
                        for( j = 0; j < service_obj->size; j++ ) {
                                const char* service = jsonObjectGetString( jsonObjectGetIndex( service_obj, j ));
                                if( service && !strcmp( appname, service ))
-                                       osrf_prefork_send_router_registration( appname, routerName, domain );
+                                       osrf_prefork_send_router_registration( appname, routerName, domain, unregister );
                        }
                }
                else if( JSON_STRING == service_obj->type ) {
                        // There's only one service listed.  Register with this router
                        // if and only if this service is the one listed.
                        if( !strcmp( appname, jsonObjectGetString( service_obj )) )
-                               osrf_prefork_send_router_registration( appname, routerName, domain );
+                               osrf_prefork_send_router_registration( appname, routerName, domain, unregister );
                }
        } else {
                // This router is not restricted to any set of services,
                // so go ahead and register with it.
-               osrf_prefork_send_router_registration( appname, routerName, domain );
+               osrf_prefork_send_router_registration( appname, routerName, domain, unregister );
        }
 }
 
@@ -283,7 +305,7 @@ static void osrf_prefork_parse_router_chunk( const char* appname, const jsonObje
 
        Called only by the parent process.
 */
-static void osrf_prefork_register_routers( const char* appname ) {
+static void osrf_prefork_register_routers( const char* appname, bool unregister ) {
 
        jsonObject* routerInfo = osrfConfigGetValueObject( NULL, "/routers/router" );
 
@@ -297,12 +319,12 @@ static void osrf_prefork_register_routers( const char* appname ) {
                        char* domain = osrfConfigGetValue( NULL, "/routers/router" );
                        osrfLogDebug( OSRF_LOG_MARK, "found simple router settings with router name %s",
                                routerName );
-                       osrf_prefork_send_router_registration( appname, routerName, domain );
+                       osrf_prefork_send_router_registration( appname, routerName, domain, unregister );
 
                        free( routerName );
                        free( domain );
                } else {
-                       osrf_prefork_parse_router_chunk( appname, routerChunk );
+                       osrf_prefork_parse_router_chunk( appname, routerChunk, unregister );
                }
        }
 
@@ -584,6 +606,10 @@ static prefork_child* launch_child( prefork_simple* forker ) {
 
        else { /* child */
 
+        // ignore the unregister-router signal.  Belt+suspenders protection 
+        // against sending USR1 to the wrong PID.
+               signal( SIGUSR1, SIG_IGN );
+
                osrfLogInternal( OSRF_LOG_MARK,
                        "I am new child with read_data_fd = %d and write_status_fd = %d",
                        child->read_data_fd, child->write_status_fd );
@@ -642,6 +668,17 @@ static void sigchld_handler( int sig ) {
 }
 
 /**
+       @brief Signal handler for SIGUSR1
+       @param sig The value of the trapped signal; always SIGUSR1.
+
+    Send unregister command to all registered routers.
+*/
+static void sigusr1_handler( int sig ) {
+    osrf_prefork_register_routers(service_name, true);
+       signal( SIGUSR1, sigusr1_handler );
+}
+
+/**
        @brief Replenish the collection of child processes, after one has terminated.
        @param forker Pointer to the prefork_simple that manages the child processes.
 

diff --git a/src/perl/lib/OpenSRF/Server.pm b/src/perl/lib/OpenSRF/Server.pm
index 7ace7cf..849e606 100644 (file)
--- a/src/perl/lib/OpenSRF/Server.pm
+++ b/src/perl/lib/OpenSRF/Server.pm
@@ -145,6 +145,7 @@ sub run {
     $SIG{TERM} = sub { $self->cleanup(0, 1); };
     $SIG{CHLD} = sub { $self->reap_children(); };
     $SIG{HUP} = sub { $self->handle_sighup(); };
+    $SIG{USR1} = sub { $self->unregister_routers; };
 
     $self->spawn_children;
     $self->build_osrf_handle;
@@ -465,7 +466,9 @@ sub spawn_child {
 
     } else { # child process
 
-        $SIG{$_} = 'DEFAULT' for (qw/INT TERM QUIT HUP CHLD/);
+        # recover default handling for any signal whose handler 
+        # may have been adopted from the parent process.
+        $SIG{$_} = 'DEFAULT' for qw/TERM INT QUIT HUP CHLD USR1 USR2/;
 
         if($self->{stderr_log}) {