Java: Fix leaking global refs

[libsigrok.git] / bindings / java / org / sigrok / core / classes / classes.i

diff --git a/bindings/java/org/sigrok/core/classes/classes.i b/bindings/java/org/sigrok/core/classes/classes.i
index 894c72f75b9d501daa582b75e744451588018df8..dda333df09dc7762a6057779f93abede14995e91 100644 (file)
--- a/bindings/java/org/sigrok/core/classes/classes.i
+++ b/bindings/java/org/sigrok/core/classes/classes.i
@@ -237,6 +237,74 @@ MAP_COMMON(const sigrok::ConfigKey *, std::set<enum sigrok::Capability>,
    $1 = jenv;
 %} 
 
+/* Thread safe JNIEnv handling */
+
+%inline {
+namespace {
+  class ScopedEnv {
+    public:
+      ScopedEnv(JavaVM *jvm);
+      ScopedEnv(const ScopedEnv &ref) = delete;
+      ~ScopedEnv();
+      JNIEnv* operator-> () { return env; }
+      operator bool () const { return (bool)env; }
+    private:
+      JavaVM *jvm;
+      JNIEnv *env;
+      int env_status;
+  };
+  ScopedEnv::ScopedEnv(JavaVM *jvm) : jvm(jvm), env(NULL) {
+    env_status = jvm->GetEnv((void **)&env, JNI_VERSION_1_2);
+    if (env_status == JNI_EDETACHED) {
+%#if defined(__ANDROID__)
+      jvm->AttachCurrentThread(&env, NULL);
+%#else
+      jvm->AttachCurrentThread((void **)&env, NULL);
+%#endif
+    }
+  }
+  ScopedEnv::~ScopedEnv() {
+    if (env_status == JNI_EDETACHED) {
+      jvm->DetachCurrentThread();
+    }
+  }
+}
+}
+
+/* "Smartpointer" for Java references. */
+
+%inline {
+namespace {
+  class GlobalRefBase
+  {
+    protected:
+      GlobalRefBase (JavaVM *jvm, jobject ref);
+      GlobalRefBase (const GlobalRefBase &ref) = delete;
+      ~GlobalRefBase ();
+      JavaVM *jvm;
+      jobject jref;
+  };
+  GlobalRefBase::GlobalRefBase (JavaVM *jvm, jobject ref) : jvm(jvm), jref(0) {
+    ScopedEnv env(jvm);
+    if (env && ref)
+      jref = env->NewGlobalRef(ref);
+  }
+  GlobalRefBase::~GlobalRefBase () {
+    ScopedEnv env(jvm);
+    if(env && jref)
+      env->DeleteGlobalRef(jref);
+  }
+  template <class Jtype>
+  class GlobalRef : private GlobalRefBase
+  {
+    public:
+      GlobalRef (JavaVM *jvm, Jtype ref) : GlobalRefBase(jvm, ref) {}
+      GlobalRef (const GlobalRef &ref) : GlobalRefBase(ref.jvm, ref.jref) {}
+      operator Jtype () const { return static_cast<Jtype>(jref); }
+  };
+}
+}
+
 /* Support Java log callbacks. */
 
 %typemap(javaimports) sigrok::Context
@@ -255,18 +323,22 @@ typedef jobject jlogcallback;
 {
   void add_log_callback(JNIEnv *env, jlogcallback obj)
   {
+    JavaVM *jvm = NULL;
+    env->GetJavaVM(&jvm);
     jclass obj_class = env->GetObjectClass(obj);
     jmethodID method = env->GetMethodID(obj_class, "run",
       "(Lorg/sigrok/core/classes/LogLevel;Ljava/lang/String;)V");
-    jclass LogLevel = (jclass) env->NewGlobalRef(
-        env->FindClass("org/sigrok/core/classes/LogLevel"));
+    GlobalRef<jclass> LogLevel(jvm, env->FindClass("org/sigrok/core/classes/LogLevel"));
     jmethodID LogLevel_init = env->GetMethodID(LogLevel, "<init>", "(JZ)V");
-    jobject obj_ref = env->NewGlobalRef(obj);
+    GlobalRef<jobject> obj_ref(jvm, obj);
 
     $self->set_log_callback([=] (
       const sigrok::LogLevel *loglevel,
       std::string message)
     {
+      ScopedEnv env(jvm);
+      if (!env)
+        throw sigrok::Error(SR_ERR);
       jlong loglevel_addr = 0;
       *(const sigrok::LogLevel **) &loglevel_addr = loglevel;
       jobject loglevel_obj = env->NewObject(
@@ -297,21 +369,24 @@ typedef jobject jdatafeedcallback;
 {
   void add_datafeed_callback(JNIEnv *env, jdatafeedcallback obj)
   {
+    JavaVM *jvm = NULL;
+    env->GetJavaVM(&jvm);
     jclass obj_class = env->GetObjectClass(obj);
     jmethodID method = env->GetMethodID(obj_class, "run",
       "(Lorg/sigrok/core/classes/Device;Lorg/sigrok/core/classes/Packet;)V");
-    jclass Device = (jclass) env->NewGlobalRef(
-        env->FindClass("org/sigrok/core/classes/Device"));
+    GlobalRef<jclass> Device(jvm, env->FindClass("org/sigrok/core/classes/Device"));
     jmethodID Device_init = env->GetMethodID(Device, "<init>", "(JZ)V");
-    jclass Packet = (jclass) env->NewGlobalRef(
-       env->FindClass("org/sigrok/core/classes/Packet"));
+    GlobalRef<jclass> Packet(jvm, env->FindClass("org/sigrok/core/classes/Packet"));
     jmethodID Packet_init = env->GetMethodID(Packet, "<init>", "(JZ)V");
-    jobject obj_ref = env->NewGlobalRef(obj);
+    GlobalRef<jobject> obj_ref(jvm, obj);
 
     $self->add_datafeed_callback([=] (
       std::shared_ptr<sigrok::Device> device,
       std::shared_ptr<sigrok::Packet> packet)
     {
+      ScopedEnv env(jvm);
+      if (!env)
+        throw sigrok::Error(SR_ERR);
       jlong device_addr = 0;
       jlong packet_addr = 0;
       *(std::shared_ptr<sigrok::Device> **) &device_addr =