java: Migrate IsrCallbacks to Java's Runnable class

Signed-off-by: Petre Eftime <petre.p.eftime@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

api/mraa/gpio.h

@@ -44,6 +44,12 @@ 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>
 

api/mraa/gpio.hpp

@@ -69,30 +69,6 @@ typedef enum {
     EDGE_FALLING = 3 /**< Interupt on falling only */
 } Edge;
 
-#if defined(SWIGJAVA)
-
-class IsrCallback
-{
-  friend class Gpio;
-  public:
-    virtual ~IsrCallback()
-    {
-    }
-    virtual void
-    run()
-    { /* empty, overloaded in Java*/
-    }
-
-  protected:
-    static void
-    generic_isr_callback(void* data)
-    {
-        IsrCallback* callback = (IsrCallback*) data;
-        callback->run();
-    }
-};
-#endif
-
 /**
  * @brief API to General Purpose IO
  *
@@ -196,13 +172,13 @@ class Gpio
 #endif
         return (Result) mraa_gpio_isr(m_gpio, (mraa_gpio_edge_t) mode, &uvwork, this);
     }
-#elif defined(SWIGJAVA)
+#elif defined(SWIGJAVA) || defined(JAVACALLBACK)
     Result
-    isr(Edge mode, IsrCallback* cb)
+    isr(Edge mode, jobject runnable)
     {
-        return (Result) mraa_gpio_isr(m_gpio, (mraa_gpio_edge_t) mode, &IsrCallback::generic_isr_callback, cb);
+        return (Result) mraa_gpio_isr(m_gpio, (mraa_gpio_edge_t) mode, mraa_java_isr_callback, runnable);
     }
-#else
+#endif
     /**
      * Sets a callback to be called when pin value changes
      *
@@ -217,7 +193,7 @@ class Gpio
     {
         return (Result) mraa_gpio_isr(m_gpio, (mraa_gpio_edge_t) mode, fptr, args);
     }
-#endif
+
     /**
      * Exits callback - this call will not kill the isr thread immediatly
      * but only when it is out of it's critical section

examples/java/Isr.java

@@ -25,7 +25,6 @@
 import mraa.Dir;
 import mraa.Edge;
 import mraa.Gpio;
-import mraa.IsrCallback;
 
 public class Isr {
     static {
@@ -41,7 +40,7 @@ public class Isr {
     public static void main(String argv[]) throws InterruptedException {
         Gpio gpio = new Gpio(6);
 
-        IsrCallback callback = new JavaCallback();
+        Runnable callback = new JavaCallback();
 
         gpio.isr(Edge.EDGE_RISING, callback);
         while (true)
@@ -49,8 +48,6 @@ public class Isr {
     };
 }
 
-class JavaCallback extends IsrCallback {
+class JavaCallback extends Runnable {
-    public JavaCallback() { super(); }
-
     public void run() { System.out.println("JavaCallback.run()"); }
 }

src/CMakeLists.txt

@@ -130,6 +130,7 @@ macro (mraa_CREATE_INSTALL_PKGCONFIG generated_file install_location)
   install (FILES ${CMAKE_CURRENT_BINARY_DIR}/${generated_file} DESTINATION ${install_location})
 endmacro (mraa_CREATE_INSTALL_PKGCONFIG)
 mraa_create_install_pkgconfig (mraa.pc ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
+mraa_create_install_pkgconfig (mraajava.pc ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
 
 install(TARGETS mraa DESTINATION ${CMAKE_INSTALL_LIBDIR})
 

src/gpio/gpio.c

@@ -234,6 +234,36 @@ 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_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);
+}
+
+#endif
+
 static void*
 mraa_gpio_interrupt_handler(void* arg)
 {
@@ -262,6 +292,22 @@ 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 (err != JNI_OK) {
+                close(dev->isr_value_fp);
+                dev->isr_value_fp = -1;
+                return NULL;
+        }
+
+        pthread_once(&env_key_init, make_env_key);
+        pthread_setspecific(env_key, jenv);
+    }
+#endif
+
     for (;;) {
         ret = mraa_gpio_wait_interrupt(dev->isr_value_fp
 #ifndef HAVE_PTHREAD_CANCEL
@@ -347,6 +393,13 @@ mraa_gpio_interrupt_handler(void* arg)
 #endif
             close(dev->isr_value_fp);
             dev->isr_value_fp = -1;
+#if defined(SWIGJAVA) || defined(JAVACALLBACK)
+
+            if(dev->isr == mraa_java_isr_callback) {
+                (*jenv)->DeleteGlobalRef(jenv, (jobject)dev->isr_args);
+                (*globVM)->DetachCurrentThread(globVM);
+            }
+#endif
             return NULL;
         }
     }
@@ -414,6 +467,16 @@ 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_8);
+        jobject grunnable = (*jenv)->NewGlobalRef(jenv, (jobject) args);
+        args = (void *) grunnable;
+    }
+#endif
     dev->isr_args = args;
     pthread_create(&dev->thread_id, NULL, mraa_gpio_interrupt_handler, (void*) dev);
 

src/java/CMakeLists.txt

@@ -10,7 +10,8 @@ include_directories (
 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)
 
-set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fpermissive")
+set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fpermissive -DJAVACALLBACK")
+set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DJAVACALLBACK")
 
 if (NOT DEFINED $ENV{JAVA_HOME_NATIVE})
   set (JAVA_HOME_NATIVE $ENV{JAVA_HOME})
@@ -29,6 +30,7 @@ add_custom_command (TARGET mraajava
   COMMAND cmake -E echo "Compiling java.."
   COMMAND cmake -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/mraa
   COMMAND ${JAVAC} *.java -d ${CMAKE_CURRENT_BINARY_DIR}
+  COMMAND cmake -E create_symlink java/libmraajava.so ${CMAKE_CURRENT_BINARY_DIR}/../libmraajava.so
   COMMAND cmake -E echo "Creating jar"
   COMMAND ${JAR} cvf mraa.jar mraa
 )
@@ -42,6 +44,9 @@ endif ()
 install (FILES ${CMAKE_CURRENT_BINARY_DIR}/libmraajava.so
 		DESTINATION lib/java
 )
+install (FILES ${CMAKE_CURRENT_BINARY_DIR}/../libmraajava.so
+		DESTINATION lib/
+)
 install (FILES ${CMAKE_CURRENT_BINARY_DIR}/mraa.jar
 		DESTINATION lib/java
 )

src/java/mraajava.i

@@ -42,6 +42,9 @@
     return $jnicall;
 }
 
+%typemap(jtype) jobject runnable "java.lang.Runnable"
+%typemap(jstype) jobject runnable "java.lang.Runnable"
+
 namespace mraa {
 class Spi;
 %typemap(out) uint8_t*
@@ -55,14 +58,18 @@ class Spi;
 
 %ignore write(const char* data, int length);
 %ignore read(char* data, int length);
+%ignore globVM;
+%ignore env_key;
+%ignore mraa_java_isr_callback;
 
-%feature("director") IsrCallback;
-SWIG_DIRECTOR_OWNED(IsrCallback)
 %include ../mraa.i
 
 %wrapper %{
+    JavaVM *globVM;
+
     jint JNI_OnLoad(JavaVM *vm, void *reserved) {
         /* initialize mraa */
+        globVM = vm;
         mraa_init();
         return JNI_VERSION_1_8;
     }

src/mraa.i

@@ -46,6 +46,7 @@
 %ignore Gpio::v8isr(uv_work_t* req);
 %ignore Gpio::v8isr(uv_work_t* req, int status);
 %ignore Gpio::uvwork(void *ctx);
+%ignore Gpio::isr(Edge mode, void (*fptr)(void*), void* args);
 
 %include "gpio.hpp"
 

src/mraajava.pc.cmake

@@ -0,0 +1,11 @@
+prefix=@CMAKE_INSTALL_PREFIX@
+exec_prefix=${prefix}
+libdir=${exec_prefix}/lib@LIB_SUFFIX@
+includedir=${prefix}/include
+
+Name: mraa
+Description: Low Level Skeleton Library for Communication
+Version: @mraa_VERSION_STRING@
+
+Libs: -L${libdir} -lmraajava
+Cflags: -I${includedir}