src/vpp-api/java/jvpp-registry/jvpp_registry.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2016 Cisco and/or its affiliates.
  * Licensed 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.
  */
 #define _GNU_SOURCE /* for strcasestr(3) */
 #include <vnet/vnet.h>

 #define vl_api_version(n,v) static u32 vpe_api_version = (v);
 #include <vpp/api/vpe.api.h>
 #undef vl_api_version


 #include <jni.h>
 #include <jvpp-common/jvpp_common.h>
 #include "io_fd_vpp_jvpp_VppJNIConnection.h"
 #include "io_fd_vpp_jvpp_JVppRegistryImpl.h"

 #include <vpp/api/vpe_msg_enum.h>
 #define vl_typedefs             /* define message structures */
 #include <vpp/api/vpe_all_api_h.h>
 #undef vl_typedefs

 #define vl_endianfun
 #include <vpp/api/vpe_all_api_h.h>
 #undef vl_endianfun

 /* instantiate all the print functions we know about */
 #define vl_print(handle, ...)
 #define vl_printfun
 #include <vpp/api/vpe_all_api_h.h>
 #undef vl_printfun

 vlib_main_t vlib_global_main;
 vlib_main_t **vlib_mains;

 /*
  * The Java runtime isn't compile w/ -fstack-protector,
  * so we have to supply missing external references for the
  * regular vpp libraries.
  */
 void __stack_chk_guard(void) __attribute__((weak));
 void __stack_chk_guard(void) {
 }

 #define CONTROL_PING_MESSAGE "control_ping"
 #define CONTROL_PING_REPLY_MESSAGE "control_ping_reply"

 typedef struct {
     /* UThread attachment */
     volatile u32 control_ping_result_ready;
     volatile i32 control_ping_retval;

     /* Control ping callback */
     jobject registryObject;
     jclass registryClass;
     jclass controlPingReplyClass;
     jclass callbackExceptionClass;
     int control_ping_msg_id;
     int control_ping_reply_msg_id;

     /* Thread cleanup */
     pthread_key_t cleanup_rx_thread_key;

     /* Connected indication */
     volatile u8 is_connected;
     u32 vpe_pid;
 } jvpp_registry_main_t;

 jvpp_registry_main_t jvpp_registry_main __attribute__((aligned (64)));

 void vl_client_add_api_signatures(vl_api_memclnt_create_t *mp) {
     /*
      * Send the main API signature in slot 0. This bit of code must
      * match the checks in ../vpe/api/api.c: vl_msg_api_version_check().
      */
     mp->api_versions[0] = clib_host_to_net_u32(vpe_api_version);
 }

 /* cleanup handler for RX thread */
 static_always_inline void cleanup_rx_thread(void *arg) {
     jvpp_main_t * jm = &jvpp_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;

     vppjni_lock(jm, 99);

     int getEnvStat = (*jm->jvm)->GetEnv(jm->jvm, (void **) &(jm->jenv),
     JNI_VERSION_1_8);
     if (getEnvStat == JNI_EVERSION) {
         clib_warning("Unsupported JNI version\n");
         rm->control_ping_retval = VNET_API_ERROR_UNSUPPORTED_JNI_VERSION;
         goto out;
     } else if (getEnvStat != JNI_EDETACHED) {
         (*jm->jvm)->DetachCurrentThread(jm->jvm);
     }
     out: vppjni_unlock(jm);
 }

 static void vl_api_control_ping_reply_t_handler(
         vl_api_control_ping_reply_t * mp) {
     jvpp_main_t * jm = &jvpp_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;
     char was_thread_connected = 0;

     // attach to java thread if not attached
     int getEnvStat = (*jm->jvm)->GetEnv(jm->jvm, (void **) &(jm->jenv),
             JNI_VERSION_1_8);
     if (getEnvStat == JNI_EDETACHED) {
         if ((*jm->jvm)->AttachCurrentThread(jm->jvm, (void **) &(jm->jenv),
                 NULL) != 0) {
             clib_warning("Failed to attach thread\n");
             rm->control_ping_retval =
                     VNET_API_ERROR_FAILED_TO_ATTACH_TO_JAVA_THREAD;
             goto out;
         }

         // workaround as we can't use pthread_cleanup_push
         pthread_key_create(&rm->cleanup_rx_thread_key, cleanup_rx_thread);
         // destructor is only called if the value of key is non null
         pthread_setspecific(rm->cleanup_rx_thread_key, (void *) 1);
         was_thread_connected = 1;
     } else if (getEnvStat == JNI_EVERSION) {
         clib_warning("Unsupported JNI version\n");
         rm->control_ping_retval = VNET_API_ERROR_UNSUPPORTED_JNI_VERSION;
         goto out;
     }

     if (was_thread_connected == 0) {
         JNIEnv *env = jm->jenv;
         if (mp->retval < 0) {
             call_on_error("controlPing", mp->context, mp->retval,
                     rm->registryClass, rm->registryObject,
                     rm->callbackExceptionClass);
         } else {
             jmethodID constructor = (*env)->GetMethodID(env,
                     rm->controlPingReplyClass, "<init>", "()V");
             jmethodID callbackMethod = (*env)->GetMethodID(env,
                     rm->registryClass, "onControlPingReply",
                     "(Lio/fd/vpp/jvpp/dto/ControlPingReply;)V");

             jobject dto = (*env)->NewObject(env, rm->controlPingReplyClass,
                     constructor);

             jfieldID contextFieldId = (*env)->GetFieldID(env,
                     rm->controlPingReplyClass, "context", "I");
             (*env)->SetIntField(env, dto, contextFieldId,
                     clib_net_to_host_u32(mp->context));

             jfieldID clientIndexFieldId = (*env)->GetFieldID(env,
                     rm->controlPingReplyClass, "clientIndex", "I");
             (*env)->SetIntField(env, dto, clientIndexFieldId,
                     clib_net_to_host_u32(mp->client_index));

             jfieldID vpePidFieldId = (*env)->GetFieldID(env,
                     rm->controlPingReplyClass, "vpePid", "I");
             (*env)->SetIntField(env, dto, vpePidFieldId,
                     clib_net_to_host_u32(mp->vpe_pid));

             (*env)->CallVoidMethod(env, rm->registryObject, callbackMethod,
                     dto);
             (*env)->DeleteLocalRef(env, dto);
         }
     }

     out: rm->vpe_pid = clib_net_to_host_u32(mp->vpe_pid);
     rm->control_ping_result_ready = 1;
 }

 static int find_ping_id() {
     int rv = 0;
     jvpp_main_t * jm = &jvpp_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;
     api_main_t *am = &api_main;
     hash_pair_t *hp;
     jm->messages_hash = am->msg_index_by_name_and_crc;

     rm->control_ping_msg_id = -1;
     rm->control_ping_reply_msg_id = -1;

     hash_foreach_pair (hp, jm->messages_hash,
     ({
         char *key = (char *)hp->key; // key format: name_crc
         int msg_name_len = strlen(key) - 9; // ignore crc
         if (strlen(CONTROL_PING_MESSAGE) == msg_name_len &&
                 strncmp(CONTROL_PING_MESSAGE, (char *)hp->key, msg_name_len) == 0) {
             rm->control_ping_msg_id = (u32)hp->value[0];
         }
         if (strlen(CONTROL_PING_REPLY_MESSAGE) == msg_name_len &&
                 strncmp(CONTROL_PING_REPLY_MESSAGE, (char *)hp->key, msg_name_len) == 0) {
             rm->control_ping_reply_msg_id  = (u32)hp->value[0];
         }
     }));
     if (rm->control_ping_msg_id == -1) {
         clib_warning("failed to find id for %s", CONTROL_PING_MESSAGE);
         rv = -1;
     }
     if (rm->control_ping_reply_msg_id == -1) {
         clib_warning("failed to find id for %s", CONTROL_PING_REPLY_MESSAGE);
         rv = -1;
     }
     return rv;
 }

 static int send_initial_control_ping() {
     f64 timeout;
     clib_time_t clib_time;
     vl_api_control_ping_t * mp;
     jvpp_main_t * jm = &jvpp_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;

     clib_time_init(&clib_time);

     rm->control_ping_result_ready = 0;
     mp = vl_msg_api_alloc(sizeof(*mp));
     memset(mp, 0, sizeof(*mp));
     mp->_vl_msg_id = ntohs(rm->control_ping_msg_id);
     mp->client_index = jm->my_client_index;

     // send message:
     vl_msg_api_send_shmem(jm->vl_input_queue, (u8 *) &mp);

     // wait for results: Current time + 10 seconds is the timeout
     timeout = clib_time_now(&clib_time) + 10.0;
     int rv = VNET_API_ERROR_RESPONSE_NOT_READY;
     while (clib_time_now(&clib_time) < timeout) {
         if (rm->control_ping_result_ready == 1) {
             rv = rm->control_ping_retval;
             break;
         }
     }

     if (rv != 0) {
         clib_warning("first control ping failed: %d", rv);
     }
     return rv;
 }

 static int connect_to_vpe(char *shm_prefix, char *name) {
     jvpp_main_t * jm = &jvpp_main;
     api_main_t * am = &api_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;

     if (vl_client_connect_to_vlib(shm_prefix, name, 32) < 0)
         return -1;
     jm->my_client_index = am->my_client_index;

     jm->vl_input_queue = am->shmem_hdr->vl_input_queue;

     if (find_ping_id() < 0)
         return -1;

     vl_msg_api_set_handlers(rm->control_ping_reply_msg_id, CONTROL_PING_REPLY_MESSAGE,
             vl_api_control_ping_reply_t_handler, vl_noop_handler,
             vl_api_control_ping_reply_t_endian,
             vl_api_control_ping_reply_t_print,
             sizeof(vl_api_control_ping_reply_t), 1);

     return send_initial_control_ping();
 }

 JNIEXPORT jobject JNICALL Java_io_fd_vpp_jvpp_VppJNIConnection_clientConnect(
         JNIEnv *env, jclass obj, jstring shmPrefix, jstring clientName) {
     /*
      * TODO introducing memory prefix as variable can be used in hc2vpp
      * to be able to run without root privileges
      * https://jira.fd.io/browse/HC2VPP-176
      */
     int rv;
     const char *client_name;
     const char *shm_prefix;
     void vl_msg_reply_handler_hookup(void);
     jvpp_main_t * jm = &jvpp_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;

     jclass connectionInfoClass = (*env)->FindClass(env,
             "io/fd/vpp/jvpp/VppJNIConnection$ConnectionInfo");
     jmethodID connectionInfoConstructor = (*env)->GetMethodID(env,
             connectionInfoClass, "<init>", "(JIII)V");

     if (rm->is_connected) {
         return (*env)->NewObject(env, connectionInfoClass,
                 connectionInfoConstructor, 0, 0,
                 VNET_API_ERROR_ALREADY_CONNECTED, 0);
     }

     client_name = (*env)->GetStringUTFChars(env, clientName, 0);
     shm_prefix = (*env)->GetStringUTFChars(env, shmPrefix, 0);

     if (!client_name) {
         return (*env)->NewObject(env, connectionInfoClass,
                 connectionInfoConstructor, 0, 0, VNET_API_ERROR_INVALID_VALUE, 0, shmPrefix);
     }

     if (!shm_prefix) {
         return (*env)->NewObject(env, connectionInfoClass,
                 connectionInfoConstructor, 0, 0, VNET_API_ERROR_INVALID_VALUE, 0, shmPrefix);
     }

     rv = connect_to_vpe((char *) shm_prefix, (char *) client_name);

     if (rv < 0)
         clib_warning("connection failed, rv %d", rv);

     (*env)->ReleaseStringUTFChars(env, clientName, client_name);
     (*env)->ReleaseStringUTFChars(env, shmPrefix, shm_prefix);

     return (*env)->NewObject(env, connectionInfoClass,
             connectionInfoConstructor, (jlong) pointer_to_uword (jm->vl_input_queue),
             (jint) jm->my_client_index, (jint) rv, (jint) rm->vpe_pid);
 }

 JNIEXPORT jint JNICALL Java_io_fd_vpp_jvpp_JVppRegistryImpl_controlPing0(
         JNIEnv *env, jobject regstryObject) {
     jvpp_main_t * jm = &jvpp_main;
     vl_api_control_ping_t * mp;
     u32 my_context_id = vppjni_get_context_id(&jvpp_main);
     jvpp_registry_main_t * rm = &jvpp_registry_main;

     if (rm->registryObject == 0) {
         rm->registryObject = (*env)->NewGlobalRef(env, regstryObject);
     }
     if (rm->registryClass == 0) {
         rm->registryClass = (jclass) (*env)->NewGlobalRef(env,
                 (*env)->GetObjectClass(env, regstryObject));
     }

     mp = vl_msg_api_alloc(sizeof(*mp));
     memset(mp, 0, sizeof(*mp));
     mp->_vl_msg_id = ntohs(rm->control_ping_msg_id);
     mp->client_index = jm->my_client_index;
     mp->context = clib_host_to_net_u32(my_context_id);

     // send message:
     vl_msg_api_send_shmem(jm->vl_input_queue, (u8 *) &mp);
     return my_context_id;
 }

 JNIEXPORT void JNICALL Java_io_fd_vpp_jvpp_VppJNIConnection_clientDisconnect(
         JNIEnv *env, jclass clazz) {
     jvpp_registry_main_t * rm = &jvpp_registry_main;
     rm->is_connected = 0; // TODO make thread safe
     vl_client_disconnect_from_vlib();

     // cleanup:
     if (rm->registryObject) {
         (*env)->DeleteGlobalRef(env, rm->registryObject);
         rm->registryObject = 0;
     }
     if (rm->registryClass) {
         (*env)->DeleteGlobalRef(env, rm->registryClass);
         rm->registryClass = 0;
     }
 }

 jint JNI_OnLoad(JavaVM *vm, void *reserved) {
     jvpp_main_t * jm = &jvpp_main;
     jvpp_registry_main_t * rm = &jvpp_registry_main;
     JNIEnv* env;

     if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_8) != JNI_OK) {
         return JNI_EVERSION;
     }

     rm->controlPingReplyClass = (jclass) (*env)->NewGlobalRef(env,
             (*env)->FindClass(env, "io/fd/vpp/jvpp/dto/ControlPingReply"));
     if ((*env)->ExceptionCheck(env)) {
         (*env)->ExceptionDescribe(env);
         clib_warning("Failed to cache class references\n");
         return JNI_ERR;
     }

     rm->callbackExceptionClass = (jclass) (*env)->NewGlobalRef(env,
             (*env)->FindClass(env, "io/fd/vpp/jvpp/VppCallbackException"));
     if ((*env)->ExceptionCheck(env)) {
         (*env)->ExceptionDescribe(env);
         return JNI_ERR;
     }

     jm->jvm = vm;
     return JNI_VERSION_1_8;
 }

 void JNI_OnUnload(JavaVM *vm, void *reserved) {
     jvpp_main_t * jm = &jvpp_main;
     JNIEnv* env;
     if ((*vm)->GetEnv(vm, (void**) &env, JNI_VERSION_1_8) != JNI_OK) {
         return;
     }

     jm->jenv = NULL;
     jm->jvm = NULL;
 }
	/*
	* Copyright (c) 2016 Cisco and/or its affiliates.
	* Licensed 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.
	*/
	#define _GNU_SOURCE /* for strcasestr(3) */
	#include <vnet/vnet.h>

	#define vl_api_version(n,v) static u32 vpe_api_version = (v);
	#include <vpp/api/vpe.api.h>
	#undef vl_api_version


	#include <jni.h>
	#include <jvpp-common/jvpp_common.h>
	#include "io_fd_vpp_jvpp_VppJNIConnection.h"
	#include "io_fd_vpp_jvpp_JVppRegistryImpl.h"

	#include <vpp/api/vpe_msg_enum.h>
	#define vl_typedefs /* define message structures */
	#include <vpp/api/vpe_all_api_h.h>
	#undef vl_typedefs

	#define vl_endianfun
	#include <vpp/api/vpe_all_api_h.h>
	#undef vl_endianfun

	/* instantiate all the print functions we know about */
	#define vl_print(handle, ...)
	#define vl_printfun
	#include <vpp/api/vpe_all_api_h.h>
	#undef vl_printfun

	vlib_main_t vlib_global_main;
	vlib_main_t **vlib_mains;

	/*
	* The Java runtime isn't compile w/ -fstack-protector,
	* so we have to supply missing external references for the
	* regular vpp libraries.
	*/
	void __stack_chk_guard(void) __attribute__((weak));
	void __stack_chk_guard(void) {
	}

	#define CONTROL_PING_MESSAGE "control_ping"
	#define CONTROL_PING_REPLY_MESSAGE "control_ping_reply"

	typedef struct {
	/* UThread attachment */
	volatile u32 control_ping_result_ready;
	volatile i32 control_ping_retval;

	/* Control ping callback */
	jobject registryObject;
	jclass registryClass;
	jclass controlPingReplyClass;
	jclass callbackExceptionClass;
	int control_ping_msg_id;
	int control_ping_reply_msg_id;

	/* Thread cleanup */
	pthread_key_t cleanup_rx_thread_key;

	/* Connected indication */
	volatile u8 is_connected;
	u32 vpe_pid;
	} jvpp_registry_main_t;

	jvpp_registry_main_t jvpp_registry_main __attribute__((aligned (64)));

	void vl_client_add_api_signatures(vl_api_memclnt_create_t *mp) {
	/*
	* Send the main API signature in slot 0. This bit of code must
	* match the checks in ../vpe/api/api.c: vl_msg_api_version_check().
	*/
	mp->api_versions[0] = clib_host_to_net_u32(vpe_api_version);
	}

	/* cleanup handler for RX thread */
	static_always_inline void cleanup_rx_thread(void *arg) {
	jvpp_main_t * jm = &jvpp_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;

	vppjni_lock(jm, 99);

	int getEnvStat = (jm->jvm)->GetEnv(jm->jvm, (void *) &(jm->jenv),
	JNI_VERSION_1_8);
	if (getEnvStat == JNI_EVERSION) {
	clib_warning("Unsupported JNI version\n");
	rm->control_ping_retval = VNET_API_ERROR_UNSUPPORTED_JNI_VERSION;
	goto out;
	} else if (getEnvStat != JNI_EDETACHED) {
	(*jm->jvm)->DetachCurrentThread(jm->jvm);
	}
	out: vppjni_unlock(jm);
	}

	static void vl_api_control_ping_reply_t_handler(
	vl_api_control_ping_reply_t * mp) {
	jvpp_main_t * jm = &jvpp_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;
	char was_thread_connected = 0;

	// attach to java thread if not attached
	int getEnvStat = (jm->jvm)->GetEnv(jm->jvm, (void *) &(jm->jenv),
	JNI_VERSION_1_8);
	if (getEnvStat == JNI_EDETACHED) {
	if ((jm->jvm)->AttachCurrentThread(jm->jvm, (void *) &(jm->jenv),
	NULL) != 0) {
	clib_warning("Failed to attach thread\n");
	rm->control_ping_retval =
	VNET_API_ERROR_FAILED_TO_ATTACH_TO_JAVA_THREAD;
	goto out;
	}

	// workaround as we can't use pthread_cleanup_push
	pthread_key_create(&rm->cleanup_rx_thread_key, cleanup_rx_thread);
	// destructor is only called if the value of key is non null
	pthread_setspecific(rm->cleanup_rx_thread_key, (void *) 1);
	was_thread_connected = 1;
	} else if (getEnvStat == JNI_EVERSION) {
	clib_warning("Unsupported JNI version\n");
	rm->control_ping_retval = VNET_API_ERROR_UNSUPPORTED_JNI_VERSION;
	goto out;
	}

	if (was_thread_connected == 0) {
	JNIEnv *env = jm->jenv;
	if (mp->retval < 0) {
	call_on_error("controlPing", mp->context, mp->retval,
	rm->registryClass, rm->registryObject,
	rm->callbackExceptionClass);
	} else {
	jmethodID constructor = (*env)->GetMethodID(env,
	rm->controlPingReplyClass, "<init>", "()V");
	jmethodID callbackMethod = (*env)->GetMethodID(env,
	rm->registryClass, "onControlPingReply",
	"(Lio/fd/vpp/jvpp/dto/ControlPingReply;)V");

	jobject dto = (*env)->NewObject(env, rm->controlPingReplyClass,
	constructor);

	jfieldID contextFieldId = (*env)->GetFieldID(env,
	rm->controlPingReplyClass, "context", "I");
	(*env)->SetIntField(env, dto, contextFieldId,
	clib_net_to_host_u32(mp->context));

	jfieldID clientIndexFieldId = (*env)->GetFieldID(env,
	rm->controlPingReplyClass, "clientIndex", "I");
	(*env)->SetIntField(env, dto, clientIndexFieldId,
	clib_net_to_host_u32(mp->client_index));

	jfieldID vpePidFieldId = (*env)->GetFieldID(env,
	rm->controlPingReplyClass, "vpePid", "I");
	(*env)->SetIntField(env, dto, vpePidFieldId,
	clib_net_to_host_u32(mp->vpe_pid));

	(*env)->CallVoidMethod(env, rm->registryObject, callbackMethod,
	dto);
	(*env)->DeleteLocalRef(env, dto);
	}
	}

	out: rm->vpe_pid = clib_net_to_host_u32(mp->vpe_pid);
	rm->control_ping_result_ready = 1;
	}

	static int find_ping_id() {
	int rv = 0;
	jvpp_main_t * jm = &jvpp_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;
	api_main_t *am = &api_main;
	hash_pair_t *hp;
	jm->messages_hash = am->msg_index_by_name_and_crc;

	rm->control_ping_msg_id = -1;
	rm->control_ping_reply_msg_id = -1;

	hash_foreach_pair (hp, jm->messages_hash,
	({
	char key = (char )hp->key; // key format: name_crc
	int msg_name_len = strlen(key) - 9; // ignore crc
	if (strlen(CONTROL_PING_MESSAGE) == msg_name_len &&
	strncmp(CONTROL_PING_MESSAGE, (char *)hp->key, msg_name_len) == 0) {
	rm->control_ping_msg_id = (u32)hp->value[0];
	}
	if (strlen(CONTROL_PING_REPLY_MESSAGE) == msg_name_len &&
	strncmp(CONTROL_PING_REPLY_MESSAGE, (char *)hp->key, msg_name_len) == 0) {
	rm->control_ping_reply_msg_id = (u32)hp->value[0];
	}
	}));
	if (rm->control_ping_msg_id == -1) {
	clib_warning("failed to find id for %s", CONTROL_PING_MESSAGE);
	rv = -1;
	}
	if (rm->control_ping_reply_msg_id == -1) {
	clib_warning("failed to find id for %s", CONTROL_PING_REPLY_MESSAGE);
	rv = -1;
	}
	return rv;
	}

	static int send_initial_control_ping() {
	f64 timeout;
	clib_time_t clib_time;
	vl_api_control_ping_t * mp;
	jvpp_main_t * jm = &jvpp_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;

	clib_time_init(&clib_time);

	rm->control_ping_result_ready = 0;
	mp = vl_msg_api_alloc(sizeof(*mp));
	memset(mp, 0, sizeof(*mp));
	mp->_vl_msg_id = ntohs(rm->control_ping_msg_id);
	mp->client_index = jm->my_client_index;

	// send message:
	vl_msg_api_send_shmem(jm->vl_input_queue, (u8 *) &mp);

	// wait for results: Current time + 10 seconds is the timeout
	timeout = clib_time_now(&clib_time) + 10.0;
	int rv = VNET_API_ERROR_RESPONSE_NOT_READY;
	while (clib_time_now(&clib_time) < timeout) {
	if (rm->control_ping_result_ready == 1) {
	rv = rm->control_ping_retval;
	break;
	}
	}

	if (rv != 0) {
	clib_warning("first control ping failed: %d", rv);
	}
	return rv;
	}

	static int connect_to_vpe(char shm_prefix, char name) {
	jvpp_main_t * jm = &jvpp_main;
	api_main_t * am = &api_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;

	if (vl_client_connect_to_vlib(shm_prefix, name, 32) < 0)
	return -1;
	jm->my_client_index = am->my_client_index;

	jm->vl_input_queue = am->shmem_hdr->vl_input_queue;

	if (find_ping_id() < 0)
	return -1;

	vl_msg_api_set_handlers(rm->control_ping_reply_msg_id, CONTROL_PING_REPLY_MESSAGE,
	vl_api_control_ping_reply_t_handler, vl_noop_handler,
	vl_api_control_ping_reply_t_endian,
	vl_api_control_ping_reply_t_print,
	sizeof(vl_api_control_ping_reply_t), 1);

	return send_initial_control_ping();
	}

	JNIEXPORT jobject JNICALL Java_io_fd_vpp_jvpp_VppJNIConnection_clientConnect(
	JNIEnv *env, jclass obj, jstring shmPrefix, jstring clientName) {
	/*
	* TODO introducing memory prefix as variable can be used in hc2vpp
	* to be able to run without root privileges
	* https://jira.fd.io/browse/HC2VPP-176
	*/
	int rv;
	const char *client_name;
	const char *shm_prefix;
	void vl_msg_reply_handler_hookup(void);
	jvpp_main_t * jm = &jvpp_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;

	jclass connectionInfoClass = (*env)->FindClass(env,
	"io/fd/vpp/jvpp/VppJNIConnection$ConnectionInfo");
	jmethodID connectionInfoConstructor = (*env)->GetMethodID(env,
	connectionInfoClass, "<init>", "(JIII)V");

	if (rm->is_connected) {
	return (*env)->NewObject(env, connectionInfoClass,
	connectionInfoConstructor, 0, 0,
	VNET_API_ERROR_ALREADY_CONNECTED, 0);
	}

	client_name = (*env)->GetStringUTFChars(env, clientName, 0);
	shm_prefix = (*env)->GetStringUTFChars(env, shmPrefix, 0);

	if (!client_name) {
	return (*env)->NewObject(env, connectionInfoClass,
	connectionInfoConstructor, 0, 0, VNET_API_ERROR_INVALID_VALUE, 0, shmPrefix);
	}

	if (!shm_prefix) {
	return (*env)->NewObject(env, connectionInfoClass,
	connectionInfoConstructor, 0, 0, VNET_API_ERROR_INVALID_VALUE, 0, shmPrefix);
	}

	rv = connect_to_vpe((char ) shm_prefix, (char ) client_name);

	if (rv < 0)
	clib_warning("connection failed, rv %d", rv);

	(*env)->ReleaseStringUTFChars(env, clientName, client_name);
	(*env)->ReleaseStringUTFChars(env, shmPrefix, shm_prefix);

	return (*env)->NewObject(env, connectionInfoClass,
	connectionInfoConstructor, (jlong) pointer_to_uword (jm->vl_input_queue),
	(jint) jm->my_client_index, (jint) rv, (jint) rm->vpe_pid);
	}

	JNIEXPORT jint JNICALL Java_io_fd_vpp_jvpp_JVppRegistryImpl_controlPing0(
	JNIEnv *env, jobject regstryObject) {
	jvpp_main_t * jm = &jvpp_main;
	vl_api_control_ping_t * mp;
	u32 my_context_id = vppjni_get_context_id(&jvpp_main);
	jvpp_registry_main_t * rm = &jvpp_registry_main;

	if (rm->registryObject == 0) {
	rm->registryObject = (*env)->NewGlobalRef(env, regstryObject);
	}
	if (rm->registryClass == 0) {
	rm->registryClass = (jclass) (*env)->NewGlobalRef(env,
	(*env)->GetObjectClass(env, regstryObject));
	}

	mp = vl_msg_api_alloc(sizeof(*mp));
	memset(mp, 0, sizeof(*mp));
	mp->_vl_msg_id = ntohs(rm->control_ping_msg_id);
	mp->client_index = jm->my_client_index;
	mp->context = clib_host_to_net_u32(my_context_id);

	// send message:
	vl_msg_api_send_shmem(jm->vl_input_queue, (u8 *) &mp);
	return my_context_id;
	}

	JNIEXPORT void JNICALL Java_io_fd_vpp_jvpp_VppJNIConnection_clientDisconnect(
	JNIEnv *env, jclass clazz) {
	jvpp_registry_main_t * rm = &jvpp_registry_main;
	rm->is_connected = 0; // TODO make thread safe
	vl_client_disconnect_from_vlib();

	// cleanup:
	if (rm->registryObject) {
	(*env)->DeleteGlobalRef(env, rm->registryObject);
	rm->registryObject = 0;
	}
	if (rm->registryClass) {
	(*env)->DeleteGlobalRef(env, rm->registryClass);
	rm->registryClass = 0;
	}
	}

	jint JNI_OnLoad(JavaVM vm, void reserved) {
	jvpp_main_t * jm = &jvpp_main;
	jvpp_registry_main_t * rm = &jvpp_registry_main;
	JNIEnv* env;

	if ((vm)->GetEnv(vm, (void*) &env, JNI_VERSION_1_8) != JNI_OK) {
	return JNI_EVERSION;
	}

	rm->controlPingReplyClass = (jclass) (*env)->NewGlobalRef(env,
	(*env)->FindClass(env, "io/fd/vpp/jvpp/dto/ControlPingReply"));
	if ((*env)->ExceptionCheck(env)) {
	(*env)->ExceptionDescribe(env);
	clib_warning("Failed to cache class references\n");
	return JNI_ERR;
	}

	rm->callbackExceptionClass = (jclass) (*env)->NewGlobalRef(env,
	(*env)->FindClass(env, "io/fd/vpp/jvpp/VppCallbackException"));
	if ((*env)->ExceptionCheck(env)) {
	(*env)->ExceptionDescribe(env);
	return JNI_ERR;
	}

	jm->jvm = vm;
	return JNI_VERSION_1_8;
	}

	void JNI_OnUnload(JavaVM vm, void reserved) {
	jvpp_main_t * jm = &jvpp_main;
	JNIEnv* env;
	if ((vm)->GetEnv(vm, (void*) &env, JNI_VERSION_1_8) != JNI_OK) {
	return;
	}

	jm->jenv = NULL;
	jm->jvm = NULL;
	}