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[java-interop] Migrate to C++ (dotnet#427)
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Context: dotnet#354

We'd like to get `src/java-interop` buildable on Windows, ideally as a
"Dynamic Link Library (DLL)" C++ project or "CMake Project".

In prototyping this, a conundrum arose: the "implicitly load symbols
from the 'host' executable" approach (commit 2526676) cannot work on
Windows, meaning we need to use the "dylib-mono" infrastructure used
in xamarin-android.

The current xamarin-android dylib-mono infrastructure is all C++,
which in turn means (at minimum) `java-interop-mono.c` needs to be in
C++ -- if not more files -- in order to use [`dylib-mono.h`][0].

Rename `src/java-interop/*.c` to `src/java-interop/*.cc`, and port the
C code to C++.

Then comes the *build* conundrum: the above renaming doesn't alter
`jni.c`, which will remain in C (until we want to update
`build-tools/jnienv-gen`), which means we need to have a build system
which supports compiling *both* C and C++ and then linking them into
the shared library.

There are two plausible answers here:

 1. Use an actual existing build system like `cmake`.
 2. Hack things until they work (5c89b90)

The problem with `cmake` is that it requires an additional build-time
dependency, and this repo doesn't have any provisioning infrastructure
or simple way to check/assert that build-time dependencies exist; it
would just error "cryptically."

(It also requires that I learn CMake, which might be a good idea...)

Additionally, a goal for eventual Windows support is to use a
"Dynamic Link Library (DLL)" C++ project type, at least to see if it's
*possible*.

Start cribbing some item group names from how `.vcxproj` files work --
rename `@(Compile)` to `@(ClCompile)`, use
`%(ClCompile.PreprocessorDefinitions)` to specify C++ `#define`
symbols, etc. -- and rework the `BuildMac` and `BuildUnixLibraries`
targets so that instead of using a single `g++` command to build
source code into a shared library, use an appropriate C or C++
compiler to compile source code into object files, then use the C++
compiler to link the object files into the final shared library.

This reduces patch complexity -- no introduction of CMake! -- while
allowing intermixing of C and C++ code.

Finally, fix a `clang` warning around the use of `DO_LOG`:

	java-interop-logger.cc(6,9): warning G7B4053DF: 'DO_LOG' macro redefined [-Wmacro-redefined] [/Users/jon/Dropbox/Developer/Java.Interop/src/java-interop/java-interop.csproj]

Next steps:

  * Import & require "dylib-mono" use.
    "'Stand alone' mono use" should be supportable by using `NULL` for
    the path to load mono from, on platforms which support this.

  * *Actual* Windows build support.

[0]: https://github.com/xamarin/xamarin-android/blob/d006fa832a8149aa9d5791bf9cc78425ca93799d/src/monodroid/jni/dylib-mono.h
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@jonpryor
jonpryor authored May 24, 2019
1 parent 2794a1a commit 7ef0be5
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Showing 8 changed files with 127 additions and 111 deletions.
123 changes: 61 additions & 62 deletions ...ava-interop/java-interop-gc-bridge-mono.c → ...va-interop/java-interop-gc-bridge-mono.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -83,8 +83,8 @@ lookup_optional_mono_thread_functions (void)
if (!h)
return;

_mono_thread_get_managed_id = dlsym (h, "mono_thread_get_managed_id");
_mono_thread_get_name_utf8 = dlsym (h, "mono_thread_get_name_utf8");
_mono_thread_get_managed_id = reinterpret_cast<MonoThreadGetManagedId>(dlsym (h, "mono_thread_get_managed_id"));
_mono_thread_get_name_utf8 = reinterpret_cast<MonoThreadGetNameUtf8>(dlsym (h, "mono_thread_get_name_utf8"));
}

static jobject
Expand All @@ -93,8 +93,8 @@ lref_to_gref (JNIEnv *env, jobject lref)
jobject g;
if (lref == 0)
return 0;
g = (*env)->NewGlobalRef (env, lref);
(*env)->DeleteLocalRef (env, lref);
g = env->NewGlobalRef (lref);
env->DeleteLocalRef (lref);
return g;
}

Expand All @@ -103,9 +103,9 @@ ensure_jnienv (JavaInteropGCBridge *bridge)
{
JavaVM *jvm = bridge->jvm;
JNIEnv *env;
if ((*bridge->jvm)->GetEnv (bridge->jvm, (void**)&env, JNI_VERSION_1_6) != JNI_OK || env == NULL) {
if (bridge->jvm->GetEnv ((void**)&env, JNI_VERSION_1_6) != JNI_OK || env == NULL) {
mono_thread_attach (mono_domain_get ());
(*jvm)->GetEnv (jvm, (void**)&env, JNI_VERSION_1_6);
jvm->GetEnv ((void**)&env, JNI_VERSION_1_6);
}
return env;
}
Expand All @@ -118,9 +118,9 @@ java_interop_gc_bridge_destroy (JavaInteropGCBridge *bridge)

JNIEnv *env = ensure_jnienv (bridge);
if (env != NULL) {
(*env)->DeleteGlobalRef (env, bridge->Runtime_instance);
(*env)->DeleteGlobalRef (env, bridge->WeakReference_class);
(*env)->DeleteGlobalRef (env, bridge->GCUserPeerable_class);
env->DeleteGlobalRef (bridge->Runtime_instance);
env->DeleteGlobalRef (bridge->WeakReference_class);
env->DeleteGlobalRef (bridge->GCUserPeerable_class);

bridge->Runtime_instance = NULL;
bridge->WeakReference_class = NULL;
Expand Down Expand Up @@ -276,37 +276,37 @@ java_interop_gc_bridge_new (JavaVM *jvm)
bridge.jvm = jvm;

JNIEnv *env;
if ((*jvm)->GetEnv (jvm, (void**) &env, JNI_VERSION_1_6) != JNI_OK)
if (jvm->GetEnv ((void**) &env, JNI_VERSION_1_6) != JNI_OK)
return NULL;

jobject Runtime_class = (*env)->FindClass (env, "java/lang/Runtime");
jclass Runtime_class = env->FindClass ("java/lang/Runtime");
if (Runtime_class != NULL) {
bridge.Runtime_gc = (*env)->GetMethodID (env, Runtime_class, "gc", "()V");
bridge.Runtime_gc = env->GetMethodID (Runtime_class, "gc", "()V");

jmethodID Runtime_getRuntime = (*env)->GetStaticMethodID (env, Runtime_class, "getRuntime", "()Ljava/lang/Runtime;");
jmethodID Runtime_getRuntime = env->GetStaticMethodID (Runtime_class, "getRuntime", "()Ljava/lang/Runtime;");
bridge.Runtime_instance = Runtime_getRuntime
? lref_to_gref (env, (*env)->CallStaticObjectMethod (env, Runtime_class, Runtime_getRuntime))
? lref_to_gref (env, env->CallStaticObjectMethod (Runtime_class, Runtime_getRuntime))
: NULL;

(*env)->DeleteLocalRef (env, Runtime_class);
env->DeleteLocalRef (Runtime_class);
}

jobject WeakReference_class = (*env)->FindClass (env, "java/lang/ref/WeakReference");
jclass WeakReference_class = env->FindClass ("java/lang/ref/WeakReference");
if (WeakReference_class != NULL) {
bridge.WeakReference_init = (*env)->GetMethodID (env, WeakReference_class, "<init>", "(Ljava/lang/Object;)V");
bridge.WeakReference_get = (*env)->GetMethodID (env, WeakReference_class, "get", "()Ljava/lang/Object;");
bridge.WeakReference_class = lref_to_gref (env, WeakReference_class);
bridge.WeakReference_init = env->GetMethodID (WeakReference_class, "<init>", "(Ljava/lang/Object;)V");
bridge.WeakReference_get = env->GetMethodID (WeakReference_class, "get", "()Ljava/lang/Object;");
bridge.WeakReference_class = static_cast<jclass>(lref_to_gref (env, WeakReference_class));
}

jobject GCUserPeerable_class = (*env)->FindClass (env, "com/xamarin/java_interop/GCUserPeerable");
jclass GCUserPeerable_class = env->FindClass ("com/xamarin/java_interop/GCUserPeerable");
if (GCUserPeerable_class) {
bridge.GCUserPeerable_add = (*env)->GetMethodID (env, GCUserPeerable_class, "jiAddManagedReference", "(Ljava/lang/Object;)V");
bridge.GCUserPeerable_clear = (*env)->GetMethodID (env, GCUserPeerable_class, "jiClearManagedReferences", "()V");
bridge.GCUserPeerable_class = lref_to_gref (env, GCUserPeerable_class);
bridge.GCUserPeerable_add = env->GetMethodID (GCUserPeerable_class, "jiAddManagedReference", "(Ljava/lang/Object;)V");
bridge.GCUserPeerable_clear = env->GetMethodID (GCUserPeerable_class, "jiClearManagedReferences", "()V");
bridge.GCUserPeerable_class = static_cast<jclass>(lref_to_gref (env, GCUserPeerable_class));
fflush (stdout);
}

JavaInteropGCBridge *p = calloc (1, sizeof (JavaInteropGCBridge));
JavaInteropGCBridge *p = static_cast<JavaInteropGCBridge*>(calloc (1, sizeof (JavaInteropGCBridge)));

if (p == NULL || bridge.jvm == NULL ||
bridge.Runtime_instance == NULL || bridge.Runtime_gc == NULL ||
Expand Down Expand Up @@ -356,7 +356,7 @@ java_interop_gc_bridge_set_bridge_processing_field (
if (bridge == NULL || type_handle.value == NULL || field_name == NULL)
return -1;

MonoType *type = type_handle.value;
MonoType *type = static_cast<MonoType*>(type_handle.value);

bridge->BridgeProcessing_type = mono_class_from_mono_type (type);
bridge->BridgeProcessing_field = mono_class_get_field_from_name (bridge->BridgeProcessing_type, field_name);
Expand All @@ -375,7 +375,7 @@ java_interop_gc_bridge_register_bridgeable_type (
if (bridge->num_bridge_types >= NUM_GC_BRIDGE_TYPES)
return -1;

MonoType *type = type_handle.value;
MonoType *type = static_cast<MonoType*>(type_handle.value);
int i = bridge->num_bridge_types;
MonoJavaGCBridgeInfo *info = &bridge->mono_java_gc_bridge_info [i];

Expand Down Expand Up @@ -527,12 +527,11 @@ log_gref (JavaInteropGCBridge *bridge, const char *format, ...)
}

static char
get_object_ref_type (JNIEnv *env, void *handle)
get_object_ref_type (JNIEnv *env, jobject handle)
{
jobjectRefType value;
if (handle == NULL)
return 'I';
value = (*env)->GetObjectRefType (env, handle);
jobjectRefType value = env->GetObjectRefType (handle);
switch (value) {
case JNIInvalidRefType: return 'I';
case JNILocalRefType: return 'L';
Expand Down Expand Up @@ -799,21 +798,21 @@ take_global_ref_java (JavaInteropGCBridge *bridge, JNIEnv *env, MonoObject *obj,
if (bridge_info == NULL)
return 0;

void *weak;
jobject weak;
mono_field_get_value (obj, bridge_info->weak_handle, &weak);

void *handle = (*env)->CallObjectMethod (env, weak, bridge->WeakReference_get);
jobject handle = env->CallObjectMethod (weak, bridge->WeakReference_get);
log_gref (bridge, "*try_take_global_2_1 obj=%p -> wref=%p handle=%p\n", obj, weak, handle);

if (handle) {
void *h = (*env)->NewGlobalRef (env, handle);
(*env)->DeleteLocalRef (env, handle);
jobject h = env->NewGlobalRef (handle);
env->DeleteLocalRef (handle);
handle = h;
java_interop_gc_bridge_gref_log_new (bridge, weak, get_object_ref_type (env, weak),
handle, get_object_ref_type (env, handle), thread_name, thread_id, "take_global_ref_java");
}
java_interop_gc_bridge_weak_gref_log_delete (bridge, weak, get_object_ref_type (env, weak), thread_name, thread_id, "take_global_ref_java");
(*env)->DeleteGlobalRef (env, weak);
env->DeleteGlobalRef (weak);
weak = NULL;
mono_field_set_value (obj, bridge_info->weak_handle, &weak);

Expand All @@ -832,19 +831,19 @@ take_weak_global_ref_java (JavaInteropGCBridge *bridge, JNIEnv *env, MonoObject
if (bridge_info == NULL)
return 0;

void *handle;
jobject handle;
mono_field_get_value (obj, bridge_info->handle, &handle);

jobject weaklocal = (*env)->NewObject (env, bridge->WeakReference_class, bridge->WeakReference_init, handle);
void *weakglobal = (*env)->NewGlobalRef (env, weaklocal);
(*env)->DeleteLocalRef (env, weaklocal);
jobject weaklocal = env->NewObject (bridge->WeakReference_class, bridge->WeakReference_init, handle);
jobject weakglobal = env->NewGlobalRef (weaklocal);
env->DeleteLocalRef (weaklocal);

log_gref (bridge, "*take_weak_2_1 obj=%p -> wref=%p handle=%p\n", obj, weakglobal, handle);
java_interop_gc_bridge_weak_gref_log_new (bridge, handle, get_object_ref_type (env, handle),
weakglobal, get_object_ref_type (env, weakglobal), thread_name, thread_id, "take_weak_global_ref_2_1_compat");

java_interop_gc_bridge_gref_log_delete (bridge, handle, get_object_ref_type (env, handle), thread_name, thread_id, "take_weak_global_ref_2_1_compat");
(*env)->DeleteGlobalRef (env, handle);
env->DeleteGlobalRef (handle);

mono_field_set_value (obj, bridge_info->weak_handle, &weakglobal);

Expand All @@ -858,10 +857,10 @@ take_global_ref_jni (JavaInteropGCBridge *bridge, JNIEnv *env, MonoObject *obj,
if (bridge_info == NULL)
return 0;

void *weak;
jobject weak;
mono_field_get_value (obj, bridge_info->handle, &weak);

void *handle = (*env)->NewGlobalRef (env, weak);
jobject handle = env->NewGlobalRef (weak);
log_gref (bridge, "*try_take_global obj=%p -> wref=%p handle=%p\n", obj, weak, handle);

if (handle) {
Expand All @@ -873,7 +872,7 @@ take_global_ref_jni (JavaInteropGCBridge *bridge, JNIEnv *env, MonoObject *obj,

java_interop_gc_bridge_weak_gref_log_delete (bridge, weak, 'W',
thread_name, thread_id, "take_global_ref_jni");
(*env)->DeleteWeakGlobalRef (env, weak);
env->DeleteWeakGlobalRef (weak);

mono_field_set_value (obj, bridge_info->handle, &handle);

Expand All @@ -889,19 +888,19 @@ take_weak_global_ref_jni (JavaInteropGCBridge *bridge, JNIEnv *env, MonoObject *
if (bridge_info == NULL)
return 0;

void *handle;
jobject handle;
mono_field_get_value (obj, bridge_info->handle, &handle);

log_gref (bridge, "*take_weak obj=%p; handle=%p\n", obj, handle);

void *weak = (*env)->NewWeakGlobalRef (env, handle);
jobject weak = env->NewWeakGlobalRef (handle);
java_interop_gc_bridge_weak_gref_log_new (bridge, handle, get_object_ref_type (env, handle),
weak, get_object_ref_type (env, weak),
thread_name, thread_id, "take_weak_global_ref_jni");

java_interop_gc_bridge_gref_log_delete (bridge, handle, get_object_ref_type (env, handle),
thread_name, thread_id, "take_weak_global_ref_jni");
(*env)->DeleteGlobalRef (env, handle);
env->DeleteGlobalRef (handle);

mono_field_set_value (obj, bridge_info->handle, &weak);

Expand All @@ -916,14 +915,14 @@ get_add_reference_method (JavaInteropGCBridge *bridge, JNIEnv *env, jobject obj,
{
if (!obj)
return NULL;
if (bridge->GCUserPeerable_class && (*env)->IsInstanceOf (env, obj, bridge->GCUserPeerable_class)) {
if (bridge->GCUserPeerable_class && env->IsInstanceOf (obj, bridge->GCUserPeerable_class)) {
return bridge->GCUserPeerable_add;
}
jclass klass = (*env)->GetObjectClass (env, obj);
jmethodID add = (*env)->GetMethodID (env, klass, "monodroidAddReference", "(Ljava/lang/Object;)V");
jclass klass = env->GetObjectClass (obj);
jmethodID add = env->GetMethodID (klass, "monodroidAddReference", "(Ljava/lang/Object;)V");
if (!add)
(*env)->ExceptionClear (env);
(*env)->DeleteLocalRef (env, klass);
env->ExceptionClear ();
env->DeleteLocalRef (klass);
return add;
}

Expand All @@ -932,14 +931,14 @@ add_reference (JavaInteropGCBridge *bridge, JNIEnv *env, MonoObject *obj, MonoJa
{
MonoClass *klass = mono_object_get_class (obj);

void *handle;
jobject handle;
mono_field_get_value (obj, bridge_info->handle, &handle);

jmethodID add_method_id = get_add_reference_method (bridge, env, handle, klass);
if (add_method_id) {
void *reffed_handle;
jobject reffed_handle;
mono_field_get_value (reffed_obj, bridge_info->handle, &reffed_handle);
(*env)->CallVoidMethod (env, handle, add_method_id, reffed_handle);
env->CallVoidMethod (handle, add_method_id, reffed_handle);
#if DEBUG
if (bridge->gref_log_level > 1)
log_gref (bridge,
Expand Down Expand Up @@ -1022,14 +1021,14 @@ get_clear_references_method (JavaInteropGCBridge *bridge, JNIEnv *env, jobject o
{
if (!obj)
return NULL;
if (bridge->GCUserPeerable_class && (*env)->IsInstanceOf (env, obj, bridge->GCUserPeerable_class)) {
if (bridge->GCUserPeerable_class && env->IsInstanceOf (obj, bridge->GCUserPeerable_class)) {
return bridge->GCUserPeerable_clear;
}
jclass klass = (*env)->GetObjectClass (env, obj);
jmethodID clear = (*env)->GetMethodID (env, klass, "monodroidClearReferences", "()V");
jclass klass = env->GetObjectClass (obj);
jmethodID clear = env->GetMethodID (klass, "monodroidClearReferences", "()V");
if (!clear)
(*env)->ExceptionClear (env);
(*env)->DeleteLocalRef (env, klass);
env->ExceptionClear ();
env->DeleteLocalRef (klass);
return clear;
}

Expand Down Expand Up @@ -1064,7 +1063,7 @@ gc_cleanup_after_java_collection (JavaInteropGCBridge *bridge, JNIEnv *env, int
if (refs_added) {
jmethodID clear_method_id = get_clear_references_method (bridge, env, jref);
if (clear_method_id) {
(*env)->CallVoidMethod (env, jref, clear_method_id);
env->CallVoidMethod (jref, clear_method_id);
} else {
#if DEBUG
if (bridge->gref_log_level > 1) {
Expand Down Expand Up @@ -1092,7 +1091,7 @@ gc_cleanup_after_java_collection (JavaInteropGCBridge *bridge, JNIEnv *env, int
static void
java_gc (JavaInteropGCBridge *bridge, JNIEnv *env)
{
(*env)->CallVoidMethod (env, bridge->Runtime_instance, bridge->Runtime_gc);
env->CallVoidMethod (bridge->Runtime_instance, bridge->Runtime_gc);
}

int
Expand Down Expand Up @@ -1121,8 +1120,8 @@ java_interop_gc_bridge_add_current_app_domain (JavaInteropGCBridge *bridge)

if (bridge->BridgeProcessing_vtables_count == bridge->BridgeProcessing_vtables_length) {
int new_length = bridge->BridgeProcessing_vtables_length + 1;
MonoDomain **new_domains = calloc (new_length, sizeof (MonoDomain*));
MonoVTable **new_vtbles = calloc (new_length, sizeof (MonoVTable*));
MonoDomain **new_domains = static_cast<MonoDomain**>(calloc (new_length, sizeof (MonoDomain*)));
MonoVTable **new_vtbles = static_cast<MonoVTable**>(calloc (new_length, sizeof (MonoVTable*)));
if (new_domains == NULL || new_vtbles == NULL) {
free (new_domains);
free (new_vtbles);
Expand Down
8 changes: 5 additions & 3 deletions src/java-interop/java-interop-jvm.c → src/java-interop/java-interop-jvm.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ java_interop_jvm_load (const char *path)
return JAVA_INTEROP_JVM_FAILED_ALREADY_LOADED;
}

jvm = calloc (1, sizeof (struct DylibJVM));
jvm = static_cast<DylibJVM*>(calloc (1, sizeof (DylibJVM)));
if (!jvm) {
return JAVA_INTEROP_JVM_FAILED_OOM;
}
Expand All @@ -38,17 +38,19 @@ java_interop_jvm_load (const char *path)

int symbols_missing = 0;

#define LOAD_SYMBOL(symbol) do { \
jvm->symbol = dlsym (jvm->dl_handle, #symbol); \
#define LOAD_SYMBOL_CAST(symbol, Type) do { \
jvm->symbol = reinterpret_cast<Type>(dlsym (jvm->dl_handle, #symbol)); \
if (!jvm->symbol) { \
log_error (LOG_DEFAULT, "Failed to load JVM symbol: %s", #symbol); \
symbols_missing = 1; \
} \
} while (0)
#define LOAD_SYMBOL(symbol) LOAD_SYMBOL_CAST(symbol, java_interop_ ## symbol ## _fptr)

LOAD_SYMBOL(JNI_CreateJavaVM);
LOAD_SYMBOL(JNI_GetCreatedJavaVMs);

#undef LOAD_SYMBOL_CAST
#undef LOAD_SYMBOL

if (symbols_missing) {
Expand Down
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