GlueGen JavaCallback: Revised: Static Java callback dispatcher, dropping native heap, support Struct UserParam ...

Implementation now generates a static Java callback dispatcher for each defined SetCallbackFunction, which gets invoked by the generated native static counterpart with all arguments required.

The static callback utilizes its own synchronization for thread-safety and fetches the required data set stored at SetCallbackFunction to dispatch the call to the users' CallbackFunction.
In case the callback has been removed already, the static callback simply bails out quietly.

The native code does not create, release or manage heap memory and therefore is considered safe.

+++

Further Struct Type UserParam are now supported including Heterogeneous UserParam mapping (read GlueGen_Mapping.*).

+++

Cleaned up code by extracting all JavaCallback emitter code into JavaCallbackEmitter class in one place,
leaving JavaMethodbindingEmitter and CMethodbindingEmitter mostly in their original stage (non-convoluted).

In this regard, I had to refactor a few function, i.e. moving CMethodbindingEmitter.getJNIMangledArg(..)
into JavaType.appendDescriptor(..) and JavaType.appendJNIDescriptor(..) while reusing the toJNIMethodDescriptor(..) conversion.

Test4JavaCallback covers and passes all cases.

1 files changed, 50 insertions, 387 deletions

diff --git a/src/java/com/jogamp/gluegen/JavaMethodBindingEmitter.java b/src/java/com/jogamp/gluegen/JavaMethodBindingEmitter.java
index 6a93973..fe4f82a 100644
--- a/src/java/com/jogamp/gluegen/JavaMethodBindingEmitter.java
+++ b/src/java/com/jogamp/gluegen/JavaMethodBindingEmitter.java
@@ -95,7 +95,7 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
   private String returnedArrayLengthExpression;
   private boolean returnedArrayLengthExpressionOnlyForComments = false;
 
-  private final JavaCallbackInfo javaCallback;
+  private final JavaCallbackEmitter javaCallbackEmitter;
 
   // A suffix used to create a temporary outgoing array of Buffers to
   // represent an array of compound type wrappers
@@ -134,7 +134,12 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
     } else {
       setCommentEmitter(defaultInterfaceCommentEmitter);
     }
-    javaCallback = cfg.setFuncToJavaCallbackMap.get(binding.getName());
+    final JavaCallbackInfo javaCallback = cfg.setFuncToJavaCallbackMap.get(binding.getName());
+    if( null != javaCallback ) {
+        javaCallbackEmitter = new JavaCallbackEmitter(cfg, binding, javaCallback, appendSignature(new StringBuilder()).toString());
+    } else {
+        javaCallbackEmitter = null;
+    }
     // !forImplementingMethodCall && !isInterface
   }
 
@@ -156,7 +161,7 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
     epilogue                      = arg.epilogue;
     returnedArrayLengthExpression = arg.returnedArrayLengthExpression;
     returnedArrayLengthExpressionOnlyForComments = arg.returnedArrayLengthExpressionOnlyForComments;
-    javaCallback                  = arg.javaCallback;
+    javaCallbackEmitter           = arg.javaCallbackEmitter;
   }
 
   public boolean isNativeMethod() { return isNativeMethod; }
@@ -262,8 +267,8 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
   }
 
   @Override
-  protected void emitReturnType()  {
-    unit.emit(getReturnTypeString(false));
+  protected StringBuilder appendReturnType(final StringBuilder buf) {
+    return buf.append(getReturnTypeString(false));
   }
 
   protected String erasedTypeString(final JavaType type, final boolean skipBuffers) {
@@ -335,33 +340,34 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
   }
 
   @Override
-  protected void emitName()  {
+  protected StringBuilder appendName(final StringBuilder buf)  {
     if (isPrivateNativeMethod) {
-      unit.emit(getNativeImplMethodName());
+      buf.append(getNativeImplMethodName());
     } else if( isInterface()) {
-      unit.emit(getInterfaceName());
+      buf.append(getInterfaceName());
     } else {
-      unit.emit(getImplName());
+      buf.append(getImplName());
     }
+    return buf;
   }
 
   @Override
-  protected int emitArguments() {
+  protected int appendArguments(final StringBuilder buf) {
     boolean needComma = false;
     int numEmitted = 0;
 
     if( hasModifier(JavaMethodBindingEmitter.NATIVE) && binding.isReturnCompoundByValue() ) {
-      unit.emit("final Class<?> _clazzBuffers");
+      buf.append("final Class<?> _clazzBuffers");
       ++numEmitted;
       needComma = true;
     }
     if (isPrivateNativeMethod  && binding.hasContainingType()) {
       // Always emit outgoing "this" argument
       if (needComma) {
-        unit.emit(", ");
+        buf.append(", ");
       }
-      unit.emit("ByteBuffer ");
-      unit.emit(javaThisArgumentName());
+      buf.append("ByteBuffer ");
+      buf.append(javaThisArgumentName());
       ++numEmitted;
       needComma = true;
     }
@@ -385,12 +391,12 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
       }
 
       if (needComma) {
-        unit.emit(", ");
+        buf.append(", ");
       }
 
-      unit.emit(erasedTypeString(type, false));
-      unit.emit(" ");
-      unit.emit(getArgumentName(i));
+      buf.append(erasedTypeString(type, false));
+      buf.append(" ");
+      buf.append(getArgumentName(i));
 
       ++numEmitted;
       needComma = true;
@@ -398,12 +404,12 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
       // Add Buffer and array index offset arguments after each associated argument
       if (forDirectBufferImplementation || forIndirectBufferAndArrayImplementation) {
         if (type.isNIOBuffer()) {
-          unit.emit(", int " + byteOffsetArgName(i));
+          buf.append(", int " + byteOffsetArgName(i));
           if(!useNIODirectOnly) {
-              unit.emit(", boolean " + isNIOArgName(i));
+              buf.append(", boolean " + isNIOArgName(i));
           }
         } else if (type.isNIOBufferArray()) {
-          unit.emit(", int[] " +  byteOffsetArrayArgName(i));
+          buf.append(", int[] " +  byteOffsetArrayArgName(i));
         }
       }
 
@@ -412,17 +418,16 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
         if(useNIOOnly) {
             throw new RuntimeException("NIO[Direct]Only "+binding+" is set, but "+getArgumentName(i)+" is a primitive array");
         }
-        unit.emit(", int " + offsetArgName(i));
+        buf.append(", int " + offsetArgName(i));
       }
     }
     if( hasModifier(JavaMethodBindingEmitter.NATIVE) &&
-        null != javaCallback )
+        null != javaCallbackEmitter )
     {
         if (needComma) {
-            unit.emit(", ");
+            buf.append(", ");
         }
-        unit.emit("String callbackSignature, Object lockObj, long[/*1*/] nativeUserParam");
-        ++numEmitted;
+        numEmitted += javaCallbackEmitter.appendJavaAdditionalJNIParameter(buf);
     }
     return numEmitted;
   }
@@ -455,125 +460,11 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
     return getArgumentName(i) + "_offset";
   }
 
-  private static final boolean DEBUG_JAVACALLBACK = false;
-
-  private final void emitJavaCallbackBirefAPIDoc(final String actionText, final String relationToKey, final String noKeyText, final String relationToFunc) {
-      unit.emit("  /** "+actionText);
-      if( javaCallback.setFuncKeyIndices.size() > 0 ) {
-          unit.emit(relationToKey);
-          unit.emit("Key { "+binding.getJavaSelectParameter(new StringBuilder(), javaCallback.setFuncKeyIndices, false).toString()+" } ");
-      } else {
-          unit.emit(noKeyText);
-      }
-      unit.emit(relationToFunc);
-      unit.emit("<br> <code>");
-      emitSignature();
-      unit.emitln("</code> **/");
-  }
-  private final void emitJavaCallbackKeyClass(final String capIfaceName, final String keyClassName) {
-      emitJavaCallbackBirefAPIDoc("", "", "", "for ");
-      unit.emitln("  public static class "+keyClassName+" {");
-      binding.forEachParameter( ( final int idx, final int consumedCount, final Type cType, final JavaType jType, final String name ) -> {
-          if( !cType.isVoid() && javaCallback.setFuncKeyIndices.contains(idx) ) {
-              unit.emitln("    public final "+jType+" "+name+";");
-              return true;
-          } else {
-              return false;
-          }
-      } );
-      unit.emitln("    public "+keyClassName+"("+binding.getJavaSelectParameter(new StringBuilder(), javaCallback.setFuncKeyIndices, false).toString()+") {");
-      binding.forEachParameter( ( final int idx, final int consumedCount, final Type cType, final JavaType jType, final String name ) -> {
-          if( !cType.isVoid() && javaCallback.setFuncKeyIndices.contains(idx) ) {
-              unit.emitln("      this."+name+" = "+name+";");
-              return true;
-          } else {
-              return false;
-          }
-      } );
-      unit.emitln("    }");
-      unit.emitln("    @Override");
-      unit.emitln("    public boolean equals(final Object o) {");
-      unit.emitln("      if( this == o ) {");
-      unit.emitln("        return true;");
-      unit.emitln("      }");
-      unit.emitln("      if( !(o instanceof "+keyClassName+") ) {");
-      unit.emitln("        return false;");
-      unit.emitln("      }");
-      {
-          final int count = binding.forEachParameter( ( final int idx, final int consumedCount, final Type cType, final JavaType jType, final String name ) -> {
-              if( !cType.isVoid() && javaCallback.setFuncKeyIndices.contains(idx) ) {
-                  if( 0 == consumedCount ) {
-                      unit.emitln("      final "+keyClassName+" o2 = ("+keyClassName+")o;");
-                      unit.emit  ("      return ");
-                  } else {
-                      unit.emitln(" &&");
-                      unit.emit  ("             ");
-                  }
-                  if( jType.isPrimitive() || idx == javaCallback.setFuncUserParamIdx ) {
-                      unit.emit(name+" == o2."+name);
-                  } else {
-                      unit.emit(name+".equals( o2."+name+" )");
-                  }
-                  return true;
-              } else {
-                  return false;
-              }
-          } );
-          if( 0 == count ) {
-              unit.emit("      return true");
-          }
-          unit.emitln(";");
-      }
-      unit.emitln("    }");
-      unit.emitln("    @Override");
-      unit.emitln("    public int hashCode() {");
-      {
-          final int count = binding.forEachParameter( ( final int idx, final int consumedCount, final Type cType, final JavaType jType, final String name ) -> {
-              if( !cType.isVoid() && javaCallback.setFuncKeyIndices.contains(idx) ) {
-                  if( 0 == consumedCount ) {
-                      unit.emitln("      // 31 * x == (x << 5) - x");
-                      unit.emit  ("      int hash = ");
-                  } else {
-                      unit.emit  ("      hash = ((hash << 5) - hash) + ");
-                  }
-                  if( jType.isPrimitive() ) {
-                      if( jType.isLong() ) {
-                          unit.emitln("HashUtil.getAddrHash32_EqualDist( "+name+" );");
-                      } else {
-                          unit.emitln(name+";");
-                      }
-                  } else {
-                      if( idx == javaCallback.setFuncUserParamIdx ) {
-                          unit.emitln("System.identityHashCode( "+name+" );");
-                      } else {
-                          unit.emitln(name+".hashCode();");
-                      }
-                  }
-                  return true;
-              } else {
-                  return false;
-              }
-          } );
-          if( 0 == count ) {
-              unit.emitln("      return 0;");
-          } else {
-              unit.emitln("      return hash;");
-          }
-      }
-      unit.emitln("    }");
-      unit.emitln("  }");
-  }
-  private final void emitJavaCallbackDataClass(final String capIfaceName, final String dataClassName) {
-      unit.emitln("  private static class "+dataClassName+" {");
-      unit.emitln("    final "+javaCallback.cbFuncTypeName+" func;");
-      unit.emitln("    final Object param;");
-      unit.emitln("    final long nativeParam;");
-      unit.emitln("    "+dataClassName+"("+javaCallback.cbFuncTypeName+" func, Object param, long nativeParam) {");
-      unit.emitln("      this.func = func;");
-      unit.emitln("      this.param = param;");
-      unit.emitln("      this.nativeParam = nativeParam;");
-      unit.emitln("    }");
-      unit.emitln("  }");
+  @Override
+  protected void emitAdditionalCode() {
+    if( null != javaCallbackEmitter && !isPrivateNativeMethod ) {
+        javaCallbackEmitter.emitJavaAdditionalCode(unit, isInterface());
+    }
   }
 
   @Override
@@ -594,201 +485,6 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
       }
       unit.emitln("  }");
     }
-    if( null != javaCallback && !isPrivateNativeMethod ) {
-        final String capIfaceName = CodeGenUtils.capitalizeString( getInterfaceName() );
-        final String lowIfaceName = CodeGenUtils.decapitalizeString( getInterfaceName() );
-        final String lockInstanceName = lowIfaceName+"Lock";
-        final String dataMapInstanceName = lowIfaceName+"DataMap";
-        final String dataInstanceName = lowIfaceName+"Data";
-        final boolean customKeyClass;
-        final String KeyClassName;
-        final boolean useDataMap;
-        if( null != javaCallback.setFuncKeyClassName ) {
-            customKeyClass = true;;
-            KeyClassName = javaCallback.setFuncKeyClassName;
-            useDataMap = true;
-        } else {
-            customKeyClass = false;
-            KeyClassName = CodeGenUtils.capitalizeString(capIfaceName+"Key");
-            useDataMap = javaCallback.setFuncKeyIndices.size() > 0;
-        }
-        final String DataClassName = CodeGenUtils.capitalizeString( javaCallback.cbFuncTypeName+"Data" );
-        final String fqUsrParamClassName = cfg.packageName()+"."+cfg.className()+"."+DataClassName;
-        unit.emitln();
-        if( isInterface() ) {
-            if( useDataMap ) {
-                if( !customKeyClass && !javaCallback.keyClassEmitted ) {
-                    emitJavaCallbackKeyClass(capIfaceName, KeyClassName);
-                    unit.emitln();
-                    javaCallback.keyClassEmitted = true;
-                }
-                emitJavaCallbackBirefAPIDoc("Returns ", "set of ", "", "for ");
-                unit.emitln("  public Set<"+KeyClassName+"> get"+capIfaceName+"Keys();");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Returns ", "whether callback ", "if callback ", "is mapped for ");
-                unit.emitln("  public boolean is"+capIfaceName+"Mapped("+KeyClassName+" key);");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Returns "+javaCallback.cbFuncTypeName+" callback ", "mapped to ", "", "for ");
-                unit.emitln("  public "+javaCallback.cbFuncTypeName+" get"+capIfaceName+"("+KeyClassName+" key);");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Returns user-param ", "mapped to ", "", "for ");
-                unit.emitln("  public Object get"+capIfaceName+"UserParam("+KeyClassName+" key);");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Releases all callback data ", "mapped via ", "", "skipping toolkit API. Favor passing `null` callback ref to ");
-                unit.emitln("  public int releaseAll"+capIfaceName+"();");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Releases callback data ", "mapped to ", "", "skipping toolkit API. Favor passing `null` callback ref to ");
-                unit.emitln("  public void release"+capIfaceName+"("+KeyClassName+" key);");
-                unit.emitln();
-            } else {
-                emitJavaCallbackBirefAPIDoc("Returns ", "whether callback ", "if callback ", "is mapped for ");
-                unit.emitln("  public boolean is"+capIfaceName+"Mapped();");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Returns "+javaCallback.cbFuncTypeName+" callback ", "mapped to ", "", "for ");
-                unit.emitln("  public "+javaCallback.cbFuncTypeName+" get"+capIfaceName+"();");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Returns user-param ", "mapped to ", "", "for ");
-                unit.emitln("  public Object get"+capIfaceName+"UserParam();");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Releases callback data ", "", "", "skipping toolkit API. Favor passing `null` callback ref to ");
-                unit.emitln("  public void release"+capIfaceName+"();");
-                unit.emitln();
-            }
-        } else {
-            if( useDataMap ) {
-                if( !customKeyClass && !javaCallback.keyClassEmitted ) {
-                    emitJavaCallbackKeyClass(capIfaceName, KeyClassName);
-                    unit.emitln();
-                    javaCallback.keyClassEmitted = true;
-                }
-                emitJavaCallbackBirefAPIDoc("Returns ", "set of ", "", "for ");
-                unit.emitln("  public final Set<"+KeyClassName+"> get"+capIfaceName+"Keys() {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      return "+dataMapInstanceName+".keySet();");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Returns ", "whether callback ", "if callback ", "is mapped for ");
-                unit.emitln("  public final boolean is"+capIfaceName+"Mapped("+KeyClassName+" key) {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      return null != "+dataMapInstanceName+".get(key);");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-
-                emitJavaCallbackBirefAPIDoc("Returns "+javaCallback.cbFuncTypeName+" callback ", "mapped to ", "", "for ");
-                unit.emitln("  public final "+javaCallback.cbFuncTypeName+" get"+capIfaceName+"("+KeyClassName+" key) {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final "+DataClassName+" value = "+dataMapInstanceName+".get(key);");
-                unit.emitln("      return null != value ? value.func : null;");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-
-                emitJavaCallbackBirefAPIDoc("Returns user-param ", "mapped to ", "", "for ");
-                unit.emitln("  public final Object get"+capIfaceName+"UserParam("+KeyClassName+" key) {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final "+DataClassName+" value = "+dataMapInstanceName+".get(key);");
-                unit.emitln("      return null != value ? value.param : null;");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Releases all callback data ", "mapped via ", "", "skipping toolkit API. Favor passing `null` callback ref to ");
-                unit.emitln("  public final int releaseAll"+capIfaceName+"() {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final Set<"+KeyClassName+"> keySet = "+dataMapInstanceName+".keySet();");
-                unit.emitln("      final "+KeyClassName+"[] keys = keySet.toArray(new "+KeyClassName+"[keySet.size()]);");
-                unit.emitln("      for(int i=0; i<keys.length; ++i) {");
-                unit.emitln("        final "+KeyClassName+" key = keys[i];");
-                unit.emitln("          release"+capIfaceName+"(key);");
-                unit.emitln("      }");
-                unit.emitln("      return keys.length;");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-                emitJavaCallbackBirefAPIDoc("Releases callback data ", "mapped to ", "", "skipping toolkit API. Favor passing `null` callback ref to ");
-                unit.emitln("  public final void release"+capIfaceName+"("+KeyClassName+" key) {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final "+DataClassName+" value = "+dataMapInstanceName+".remove(key);");
-                if( DEBUG_JAVACALLBACK ) {
-                    unit.emitln("      System.err.println(\"ZZZ Release \"+key+\" -> value.nativeParam 0x\"+Long.toHexString(null!=value?value.nativeParam:0));");
-                }
-                unit.emitln("      if( null != value ) {");
-                unit.emitln("        release"+capIfaceName+"Impl(value.nativeParam);");
-                unit.emitln("      }");
-                unit.emitln("    }");
-                unit.emitln("  }");
-            } else {
-                emitJavaCallbackBirefAPIDoc("Returns ", "whether callback ", "if callback ", "is mapped for ");
-                unit.emitln("  public final boolean is"+capIfaceName+"Mapped() {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      return null != "+dataInstanceName+";");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-
-                emitJavaCallbackBirefAPIDoc("Returns "+javaCallback.cbFuncTypeName+" callback ", "mapped to ", "", "for ");
-                unit.emitln("  public final "+javaCallback.cbFuncTypeName+" get"+capIfaceName+"() {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final "+DataClassName+" value = "+dataInstanceName+";");
-                unit.emitln("      return null != value ? value.func : null;");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-
-                emitJavaCallbackBirefAPIDoc("Returns user-param ", "mapped to ", "", "for ");
-                unit.emitln("  public final Object get"+capIfaceName+"UserParam() {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final "+DataClassName+" value = "+dataInstanceName+";");
-                unit.emitln("      return null != value ? value.param : null;");
-                unit.emitln("    }");
-                unit.emitln("  }");
-                unit.emitln();
-
-                emitJavaCallbackBirefAPIDoc("Releases callback data ", "", "", "skipping toolkit API. Favor passing `null` callback ref to ");
-                unit.emitln("  public final void release"+capIfaceName+"() {");
-                unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-                unit.emitln("      final "+DataClassName+" value = "+dataInstanceName+";");
-                unit.emitln("      "+dataInstanceName+" = null;");
-                if( DEBUG_JAVACALLBACK ) {
-                    unit.emitln("      System.err.println(\"ZZZ Release \"+key+\" -> value.nativeParam 0x\"+Long.toHexString(null!=value?value.nativeParam:0));");
-                }
-                unit.emitln("      if( null != value ) {");
-                unit.emitln("        release"+capIfaceName+"Impl(value.nativeParam);");
-                unit.emitln("      }");
-                unit.emitln("    }");
-                unit.emitln("  }");
-            }
-            unit.emitln("  private native void release"+capIfaceName+"Impl(long nativeUserParam);");
-            unit.emitln();
-            unit.emitln("  private final void add"+capIfaceName+"("+binding.getJavaSelectParameter(new StringBuilder(), javaCallback.setFuncKeyIndices, true).toString()+DataClassName+" value) {");
-            if( useDataMap ) {
-                unit.emitln("    final "+KeyClassName+" key = new "+KeyClassName+"("+binding.getJavaCallSelectArguments(new StringBuilder(), javaCallback.setFuncKeyIndices, false).toString()+");");
-                unit.emitln("    final "+DataClassName+" old = "+dataMapInstanceName+".put(key, value);");
-            } else {
-                unit.emitln("    final "+DataClassName+" old = "+dataInstanceName+";");
-                unit.emitln("    "+dataInstanceName+" = value;");
-            }
-            if( DEBUG_JAVACALLBACK ) {
-                unit.emitln("    System.err.println(\"ZZZ Map \"+key+\" -> value.nativeParam 0x\"+Long.toHexString(null!=value?value.nativeParam:0));");
-            }
-            unit.emitln("    if( null != old ) {");
-            unit.emitln("      release"+capIfaceName+"Impl(old.nativeParam);");
-            unit.emitln("    }");
-            unit.emitln("  }");
-            if( !cfg.emittedJavaCallbackUserParamClasses.contains(fqUsrParamClassName) ) {
-                emitJavaCallbackDataClass(capIfaceName, DataClassName);
-                cfg.emittedJavaCallbackUserParamClasses.add(fqUsrParamClassName);
-            }
-            if( useDataMap ) {
-                unit.emitln("  private final Map<"+KeyClassName+", "+DataClassName+"> "+dataMapInstanceName+" = new HashMap<"+KeyClassName+", "+DataClassName+">();");
-            } else {
-                unit.emitln("  private "+DataClassName+" "+dataInstanceName+" = null;");
-            }
-            unit.emitln("  private final Object "+lockInstanceName+" = new Object();");
-            unit.emitln();
-        }
-    }
   }
 
   protected void emitPrologueOrEpilogue(final List<String> code) {
@@ -901,15 +597,11 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
 
   protected void emitReturnVariableSetupAndCall(final MethodBinding binding) {
     final JavaType returnType = binding.getJavaReturnType();
+
     boolean needsResultAssignment = false;
-    final String capIfaceName = CodeGenUtils.capitalizeString( getInterfaceName() );
 
-    if( null != javaCallback ) {
-        final String lowIfaceName = CodeGenUtils.decapitalizeString( getInterfaceName() );
-        final String lockInstanceName = lowIfaceName+"Lock";
-        unit.emitln("    synchronized( "+lockInstanceName+" ) {");
-        unit.emitln("      final long[] nativeUserParam = { 0 };");
-        unit.emitln();
+    if( null != javaCallbackEmitter ) {
+        javaCallbackEmitter.emitJavaSetFuncPreCall(unit);
     }
     if (!returnType.isVoid()) {
       unit.emit("      ");
@@ -941,36 +633,9 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
     emitCall(binding);
     unit.emitln();
 
-    if( null != javaCallback ) {
-        final String funcArgName = binding.getArgumentName(javaCallback.setFuncCBParamIdx);
-        final String userParamArgName = binding.getArgumentName(javaCallback.setFuncUserParamIdx);
-        final String DataClassName = CodeGenUtils.capitalizeString( javaCallback.cbFuncTypeName+"Data" );
-        final String KeyClassName;
-        final boolean useDataMap;
-        if( null != javaCallback.setFuncKeyClassName ) {
-            KeyClassName = javaCallback.setFuncKeyClassName;
-            useDataMap = true;
-        } else {
-            KeyClassName = CodeGenUtils.capitalizeString(capIfaceName+"Key");
-            useDataMap = javaCallback.setFuncKeyIndices.size() > 0;
-        }
-        if( DEBUG_JAVACALLBACK ) {
-            unit.emitln("    System.err.println(\"ZZZ returned nativeUserParam 0x\"+Long.toHexString(nativeUserParam[0]));");
-        }
+    if( null != javaCallbackEmitter ) {
         unit.emitln();
-        unit.emitln("      if( 0 != nativeUserParam[0] ) {");
-        unit.emitln("          // callback registrated -> add will release a previously mapped instance ");
-        unit.emitln("          add"+capIfaceName+"("+binding.getJavaCallSelectArguments(new StringBuilder(), javaCallback.setFuncKeyIndices, true).toString()+
-                                                   "new "+DataClassName+"("+funcArgName+", "+userParamArgName+", nativeUserParam[0]));");
-        unit.emitln("      } else {");
-        unit.emitln("          // callback released (null func) -> release a previously mapped instance ");
-        if( useDataMap ) {
-            unit.emitln("          release"+capIfaceName+"( new "+KeyClassName+"( "+binding.getJavaCallSelectArguments(new StringBuilder(), javaCallback.setFuncKeyIndices, false).toString()+" ) );");
-        } else {
-            unit.emitln("          release"+capIfaceName+"();");
-        }
-        unit.emitln("      }");
-        unit.emitln("    } // synchronized ");
+        javaCallbackEmitter.emitJavaSetFuncPostCall(unit);
     }
 
     emitPostCallCleanup(binding);
@@ -1094,14 +759,13 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
       needComma = true;
       ++numArgsEmitted;
     }
-    if( null != javaCallback ) {
-        final String lowIfaceName = CodeGenUtils.decapitalizeString( getInterfaceName() );
-        final String lockInstanceName = lowIfaceName+"Lock";
+    if( null != javaCallbackEmitter ) {
         if (needComma) {
             unit.emit(", ");
         }
-        unit.emit("\"" + javaCallback.cbMethodSignature + "\", "+lockInstanceName+", nativeUserParam");
-        ++numArgsEmitted;
+        final StringBuilder buf = new StringBuilder();
+        numArgsEmitted += javaCallbackEmitter.appendJavaAdditionalJNIArguments(buf);
+        unit.emit(buf.toString());
     }
     return numArgsEmitted;
   }
@@ -1301,12 +965,11 @@ public class JavaMethodBindingEmitter extends FunctionEmitter {
     }
   }
 
-    protected class InterfaceCommentEmitter extends JavaMethodBindingEmitter.DefaultCommentEmitter {
-
-        @Override
-        protected void emitBeginning(final FunctionEmitter emitter, final PrintWriter writer) {
-            writer.print("Interface to C language function: <br> ");
-        }
+  protected class InterfaceCommentEmitter extends JavaMethodBindingEmitter.DefaultCommentEmitter {
+    @Override
+    protected void emitBeginning(final FunctionEmitter emitter, final PrintWriter writer) {
+        writer.print("Interface to C language function: <br> ");
     }
+  }
 }