Merge pull request #558 from ethereum/java-execute-alloc

java: allocate execute result in C

Author: chfast

bindings/java/c/evmc-vm.c

@@ -78,14 +78,27 @@ JNIEXPORT void JNICALL Java_org_ethereum_evmc_EvmcVm_destroy(JNIEnv* jenv,
     evmc_destroy(evm);
 }
 
-JNIEXPORT void JNICALL Java_org_ethereum_evmc_EvmcVm_execute(JNIEnv* jenv,
-                                                             jclass jcls,
-                                                             jobject jevm,
-                                                             jobject jcontext,
-                                                             jint jrev,
-                                                             jobject jmsg,
-                                                             jobject jcode,
-                                                             jobject jresult)
+static jobject AllocateDirect(JNIEnv* jenv, size_t capacity)
+{
+    const char java_class_name[] = "java/nio/ByteBuffer";
+    const char java_method_name[] = "allocateDirect";
+    const char java_method_signature[] = "(I)Ljava/nio/ByteBuffer;";
+
+    jclass jcls = (*jenv)->FindClass(jenv, java_class_name);
+    assert(jcls != NULL);
+    jmethodID method =
+        (*jenv)->GetStaticMethodID(jenv, jcls, java_method_name, java_method_signature);
+    assert(method != NULL);
+    return (*jenv)->CallStaticObjectMethod(jenv, jcls, method, capacity);
+}
+
+JNIEXPORT jobject JNICALL Java_org_ethereum_evmc_EvmcVm_execute(JNIEnv* jenv,
+                                                                jclass jcls,
+                                                                jobject jevm,
+                                                                jobject jcontext,
+                                                                jint jrev,
+                                                                jobject jmsg,
+                                                                jobject jcode)
 {
     (void)jcls;
     struct evmc_message* msg = (struct evmc_message*)(*jenv)->GetDirectBufferAddress(jenv, jmsg);
@@ -95,11 +108,14 @@ JNIEXPORT void JNICALL Java_org_ethereum_evmc_EvmcVm_execute(JNIEnv* jenv,
     struct evmc_vm* evm = (struct evmc_vm*)(*jenv)->GetDirectBufferAddress(jenv, jevm);
     assert(evm != NULL);
     const struct evmc_host_interface* host = evmc_java_get_host_interface();
+    jobject jresult = AllocateDirect(jenv, sizeof(struct evmc_result));
+    assert(jresult != NULL);
     struct evmc_result* result =
         (struct evmc_result*)(*jenv)->GetDirectBufferAddress(jenv, jresult);
     assert(result != NULL);
     *result = evmc_execute(evm, host, (struct evmc_host_context*)jcontext, (enum evmc_revision)jrev,
                            msg, code, code_size);
+    return jresult;
 }
 
 JNIEXPORT jint JNICALL Java_org_ethereum_evmc_EvmcVm_get_1capabilities(JNIEnv* jenv,
@@ -130,10 +146,3 @@ JNIEXPORT jint JNICALL Java_org_ethereum_evmc_EvmcVm_set_1option(JNIEnv* jenv,
     (*jenv)->ReleaseStringUTFChars(jenv, jval, value);
     return (jint)option_result;
 }
-
-JNIEXPORT jint JNICALL Java_org_ethereum_evmc_EvmcVm_get_1result_1size(JNIEnv* jenv, jclass jcls)
-{
-    (void)jenv;
-    (void)jcls;
-    return sizeof(struct evmc_result);
-}

bindings/java/java/src/main/java/org/ethereum/evmc/EvmcVm.java

@@ -143,13 +143,8 @@ public String version() {
    *
    * <p>This is a mandatory method and MUST NOT be set to NULL.
    */
-  private static native void execute(
-      ByteBuffer nativeVm,
-      HostContext context,
-      int rev,
-      ByteBuffer msg,
-      ByteBuffer code,
-      ByteBuffer result);
+  private static native ByteBuffer execute(
+      ByteBuffer nativeVm, HostContext context, int rev, ByteBuffer msg, ByteBuffer code);
 
   /**
    * Function is a wrapper around native execute.
@@ -158,10 +153,7 @@ private static native void execute(
    */
   public synchronized ByteBuffer execute(
       HostContext context, int rev, ByteBuffer msg, ByteBuffer code) {
-    int resultSize = get_result_size();
-    ByteBuffer result = ByteBuffer.allocateDirect(resultSize);
-    execute(nativeVm, context, rev, msg, code, result);
-    return result;
+    return execute(nativeVm, context, rev, msg, code);
   }
 
   /**
@@ -193,9 +185,6 @@ public int set_option(String name, String value) {
     return set_option(nativeVm, name, value);
   }
 
-  /** get size of result struct */
-  private static native int get_result_size();
-
   /** This method cleans up resources. */
   @Override
   public void close() {