java: mraa jni library now dynamically links to libmraa

libmraajava.so was statically linking to mraa object files causing
duplicate mraa platform instances if a UPM Java module was also loaded.

JNI functionality has been moved into src/java/mraajni.c. JVM object is
now set when JVM is loaded; see updates to src/java/mraajava.i.
This was necessary as the JVM object cannot be directly referenced from
mraa as it will not be available when building C/C++ examples.

Signed-off-by: Henry Bruce <henry.bruce@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa/gpio.h

@@ -44,15 +44,8 @@ extern "C" {
 #include <Python.h>
 #endif
 
-#if defined(SWIGJAVA) || defined(JAVACALLBACK)
-#include <jni.h>
-extern JavaVM *globVM;
-extern void mraa_java_isr_callback(void *);
-#endif
-
 #include <stdio.h>
 #include <pthread.h>
-
 #include "common.h"
 
 /**

api/mraa/gpio.hpp

@@ -28,6 +28,13 @@
 #include "types.hpp"
 #include <stdexcept>
 
+#if defined(SWIGJAVA) || defined(JAVACALLBACK)
+extern "C" {
+    void mraa_java_isr_callback(void *args);
+}
+#endif
+
+
 #if defined(SWIGJAVASCRIPT)
 #if NODE_MODULE_VERSION >= 0x000D
 #include <uv.h>

include/java/mraajni.h

@@ -0,0 +1,44 @@
+/*
+ * Author: Henry bruce <henry.bruce@intel.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "jni.h"
+#include "mraa/types.h"
+
+void mraa_java_set_jvm(JavaVM* vm);
+void mraa_java_isr_callback(void *args);
+mraa_result_t mraa_java_attach_thread();
+void mraa_java_detach_thread();
+void* mraa_java_create_global_ref(void* args);
+void mraa_java_delete_global_ref(void* ref);
+
+#ifdef __cplusplus
+}
+#endif
+

src/CMakeLists.txt

@@ -117,17 +117,6 @@ set (mraa_LIB_GLOB_HEADERS
   ${PROJECT_SOURCE_DIR}/api/mraa.hpp
 )
 
-add_library (mraa ${mraa_LIB_SRCS})
-
-
-target_link_libraries (mraa ${mraa_LIBS})
-
-set_target_properties(
-   mraa
-   PROPERTIES
-   SOVERSION ${mraa_VERSION_MAJOR}
-   VERSION ${mraa_VERSION_STRING}
-)
 install (FILES ${mraa_LIB_GLOB_HEADERS} DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
 install (DIRECTORY ${PROJECT_SOURCE_DIR}/api/mraa/ DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/mraa)
 
@@ -137,7 +126,6 @@ macro (mraa_CREATE_INSTALL_PKGCONFIG generated_file install_location)
 endmacro (mraa_CREATE_INSTALL_PKGCONFIG)
 mraa_create_install_pkgconfig (mraa.pc ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 
-install(TARGETS mraa DESTINATION ${CMAKE_INSTALL_LIBDIR})
 
 if (DOXYGEN_FOUND)
   set (CMAKE_SWIG_FLAGS -DDOXYGEN=${DOXYGEN_FOUND})
@@ -187,6 +175,15 @@ if (BUILDSWIG)
       add_subdirectory (python)
     endif ()
     if (BUILDSWIGJAVA)
+      FIND_PACKAGE (JNI REQUIRED)
+      include_directories (
+        ${JAVA_INCLUDE_PATH}
+        ${JAVA_INCLUDE_PATH2}
+        ${CMAKE_CURRENT_SOURCE_DIR}/..
+      )
+      set (mraa_LIB_SRCS ${mraa_LIB_SRCS} ${CMAKE_CURRENT_SOURCE_DIR}/java/mraajni.c)
+      set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fpermissive -DJAVACALLBACK")
+      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DJAVACALLBACK")
       add_subdirectory (java)
     endif ()
     if (BUILDSWIGNODE)
@@ -198,3 +195,13 @@ if (BUILDSWIG)
     endif ()
   endif ()
 endif ()
+
+add_library (mraa ${mraa_LIB_SRCS})
+target_link_libraries (mraa ${mraa_LIBS})
+set_target_properties(
+   mraa
+   PROPERTIES
+   SOVERSION ${mraa_VERSION_MAJOR}
+   VERSION ${mraa_VERSION_STRING}
+)
+install(TARGETS mraa DESTINATION ${CMAKE_INSTALL_LIBDIR})

src/gpio/gpio.c

@@ -24,6 +24,9 @@
  */
 #include "gpio.h"
 #include "mraa_internal.h"
+#if defined(SWIGJAVA) || defined(JAVACALLBACK)
+#include "java/mraajni.h"
+#endif
 
 #include <stdlib.h>
 #include <fcntl.h>
@@ -234,36 +237,6 @@ mraa_gpio_wait_interrupt(int fd
     return MRAA_SUCCESS;
 }
 
-#if defined(SWIGJAVA) || defined(JAVACALLBACK)
-pthread_key_t env_key;
-
-extern JavaVM *globVM;
-static pthread_once_t env_key_init = PTHREAD_ONCE_INIT;
-
-jmethodID runGlobal;
-
-static void make_env_key(void)
-{
-
-    JNIEnv *jenv;
-    (*globVM)->GetEnv(globVM, (void **)&jenv, JNI_VERSION_1_6);
-
-    jclass rcls = (*jenv)->FindClass(jenv, "java/lang/Runnable");
-    jmethodID runm = (*jenv)->GetMethodID(jenv, rcls, "run", "()V");
-
-    runGlobal = (jmethodID)(*jenv)->NewGlobalRef(jenv, (jobject)runm);
-
-    pthread_key_create(&env_key, NULL);
-}
-
-void mraa_java_isr_callback(void* data)
-{
-    JNIEnv *jenv = (JNIEnv *) pthread_getspecific(env_key);
-    (*jenv)->CallVoidMethod(jenv, (jobject)data, runGlobal);
-}
-
-#endif
-
 static void*
 mraa_gpio_interrupt_handler(void* arg)
 {
@@ -296,18 +269,12 @@ mraa_gpio_interrupt_handler(void* arg)
     dev->isr_value_fp = fp;
 
 #if defined(SWIGJAVA) || defined(JAVACALLBACK)
-    JNIEnv *jenv;
     if(dev->isr == mraa_java_isr_callback) {
-        jint err = (*globVM)->AttachCurrentThreadAsDaemon(globVM, (void **)&jenv, NULL);
+        if (mraa_java_attach_thread() != MRAA_SUCCESS) {
-
+            close(dev->isr_value_fp);
-        if (err != JNI_OK) {
+            dev->isr_value_fp = -1;
-                close(dev->isr_value_fp);
+            return NULL;
-                dev->isr_value_fp = -1;
-                return NULL;
         }
-
-        pthread_once(&env_key_init, make_env_key);
-        pthread_setspecific(env_key, jenv);
     }
 #endif
 
@@ -403,10 +370,9 @@ mraa_gpio_interrupt_handler(void* arg)
                 dev->isr_value_fp = -1;
             }
 #if defined(SWIGJAVA) || defined(JAVACALLBACK)
-
             if(dev->isr == mraa_java_isr_callback) {
-                (*jenv)->DeleteGlobalRef(jenv, (jobject)dev->isr_args);
+                mraa_java_delete_global_ref(dev->isr_args);
-                (*globVM)->DetachCurrentThread(globVM);
+                mraa_java_detach_thread();
             }
 #endif
             return NULL;
@@ -477,13 +443,10 @@ mraa_gpio_isr(mraa_gpio_context dev, mraa_gpio_edge_t mode, void (*fptr)(void*),
 
     dev->isr = fptr;
 #if defined(SWIGJAVA) || defined(JAVACALLBACK)
-    JNIEnv *jenv;
     /* Most UPM sensors use the C API, the global ref must be created here. */
     /* The reason for checking the callback function is internal callbacks. */
     if (fptr == mraa_java_isr_callback) {
-        (*globVM)->GetEnv(globVM, (void **)&jenv, JNI_VERSION_1_6);
+        args = mraa_java_create_global_ref(args);
-        jobject grunnable = (*jenv)->NewGlobalRef(jenv, (jobject) args);
-        args = (void *) grunnable;
     }
 #endif
     dev->isr_args = args;

src/java/CMakeLists.txt

@@ -1,11 +1,3 @@
-FIND_PACKAGE (JNI REQUIRED)
-
-include_directories (
-  ${JAVA_INCLUDE_PATH}
-  ${JAVA_INCLUDE_PATH2}
-  ${CMAKE_CURRENT_SOURCE_DIR}/..
-)
-
 # SWIG treats SWIG_FLAGS as a list and not a string so semicolon seperation is required
 set_source_files_properties (mraajava.i PROPERTIES SWIG_FLAGS ";-package;mraa;-I${CMAKE_BINARY_DIR}/src")
 set_source_files_properties (mraajava.i PROPERTIES CPLUSPLUS ON)
@@ -25,8 +17,8 @@ else ()
   set (JAR $ENV{JAVA_HOME_NATIVE}/bin/jar)
 endif ()
 
-swig_add_module (mraajava java mraajava.i ${mraa_LIB_SRCS})
+swig_add_module (mraajava java mraajava.i)
-swig_link_libraries (mraajava ${JAVA_LIBRARIES} ${mraa_LIBS})
+swig_link_libraries (mraajava ${JAVA_LIBRARIES} mraa)
 
 add_custom_command (TARGET mraajava
   POST_BUILD

src/java/mraajava.i

@@ -65,11 +65,11 @@ class Spi;
 %include ../mraa.i
 
 %wrapper %{
-    JavaVM *globVM;
+    #include "java/mraajni.h"
 
     jint JNI_OnLoad(JavaVM *vm, void *reserved) {
         /* initialize mraa */
-        globVM = vm;
+        mraa_java_set_jvm(vm);
         mraa_init();
         return JNI_VERSION_1_6;
     }

src/java/mraajni.c

@@ -0,0 +1,103 @@
+/*
+ * Author: Henry Bruce <henry.bruce@intel.com>
+ * Copyright (c) 2016 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <pthread.h>
+#include "java/mraajni.h"
+
+static pthread_key_t env_key;
+static pthread_once_t env_key_init = PTHREAD_ONCE_INIT;
+static jmethodID runGlobal;
+static JavaVM* globVM = NULL;
+
+
+void
+mraa_java_set_jvm(JavaVM* vm)
+{
+    globVM = vm;
+}
+
+static void
+mraa_java_make_env_key(void)
+{
+    if (globVM != NULL) {
+        JNIEnv *jenv;
+        (*globVM)->GetEnv(globVM, (void **)&jenv, JNI_VERSION_1_8);
+        jclass rcls = (*jenv)->FindClass(jenv, "java/lang/Runnable");
+        jmethodID runm = (*jenv)->GetMethodID(jenv, rcls, "run", "()V");
+        runGlobal = (jmethodID)(*jenv)->NewGlobalRef(jenv, (jobject)runm);
+        pthread_key_create(&env_key, NULL);
+    }
+}
+
+void
+mraa_java_isr_callback(void* data)
+{
+    JNIEnv *jenv = (JNIEnv *) pthread_getspecific(env_key);
+    (*jenv)->CallVoidMethod(jenv, (jobject)data, runGlobal);
+}
+
+mraa_result_t
+mraa_java_attach_thread()
+{
+    if (globVM != NULL) {
+        JNIEnv *jenv;
+        jint err = (*globVM)->AttachCurrentThreadAsDaemon(globVM, (void **)&jenv, NULL);
+        if (err == JNI_OK) {
+            pthread_once(&env_key_init, mraa_java_make_env_key);
+            pthread_setspecific(env_key, jenv);
+            return MRAA_SUCCESS;
+        }
+    }
+    return MRAA_ERROR_UNSPECIFIED;
+}
+
+void
+mraa_java_detach_thread()
+{
+    if (globVM != NULL)
+        (*globVM)->DetachCurrentThread(globVM);
+}
+
+void*
+mraa_java_create_global_ref(void* args)
+{
+    if (globVM != NULL) {
+        JNIEnv *jenv;
+        (*globVM)->GetEnv(globVM, (void **)&jenv, JNI_VERSION_1_8);
+        jobject grunnable = (*jenv)->NewGlobalRef(jenv, (jobject) args);
+        return (void *)grunnable;
+    } else
+        return NULL;
+}
+
+void
+mraa_java_delete_global_ref(void *ref)
+{
+    if (globVM != NULL) {
+        JNIEnv *jenv;
+        (*globVM)->GetEnv(globVM, (void **)&jenv, JNI_VERSION_1_8);
+        (*jenv)->DeleteGlobalRef(jenv, (jobject)ref);
+    }
+}
+