Bug 1566583 - Bridge GeckoResult to MozPromise and return a GeckoResult from GeckoProcessManager::start. r=snorp

Differential Revision: https://phabricator.services.mozilla.com/D38436

--HG--
extra : moz-landing-system : lando

ipc/glue/GeckoChildProcessHost.cpp

@@ -265,10 +265,9 @@ class AndroidProcessLauncher : public PosixProcessLauncher {
 
  protected:
   virtual RefPtr<ProcessHandlePromise> DoLaunch() override;
-  void LaunchAndroidService(
+  RefPtr<ProcessHandlePromise> LaunchAndroidService(
       const char* type, const std::vector<std::string>& argv,
-      const base::file_handle_mapping_vector& fds_to_remap,
-      base::ProcessHandle* process_handle);
+      const base::file_handle_mapping_vector& fds_to_remap);
 };
 typedef AndroidProcessLauncher ProcessLauncher;
 // NB: Technically Android is linux (i.e. XP_LINUX is defined), but we want
@@ -1136,12 +1135,8 @@ bool PosixProcessLauncher::DoSetup() {
 
 #if defined(MOZ_WIDGET_ANDROID)
 RefPtr<ProcessHandlePromise> AndroidProcessLauncher::DoLaunch() {
-  ProcessHandle handle = 0;
-  LaunchAndroidService(ChildProcessType(), mChildArgv,
-                       mLaunchOptions->fds_to_remap, &handle);
-  return handle != 0
-             ? ProcessHandlePromise::CreateAndResolve(handle, __func__)
-             : ProcessHandlePromise::CreateAndReject(LaunchError{}, __func__);
+  return LaunchAndroidService(ChildProcessType(), mChildArgv,
+                              mLaunchOptions->fds_to_remap);
 }
 #endif  // MOZ_WIDGET_ANDROID
 
@@ -1553,10 +1548,9 @@ void GeckoChildProcessHost::GetQueuedMessages(std::queue<IPC::Message>& queue) {
 }
 
 #ifdef MOZ_WIDGET_ANDROID
-void AndroidProcessLauncher::LaunchAndroidService(
+RefPtr<ProcessHandlePromise> AndroidProcessLauncher::LaunchAndroidService(
     const char* type, const std::vector<std::string>& argv,
-    const base::file_handle_mapping_vector& fds_to_remap,
-    base::ProcessHandle* process_handle) {
+    const base::file_handle_mapping_vector& fds_to_remap) {
   MOZ_RELEASE_ASSERT((2 <= fds_to_remap.size()) && (fds_to_remap.size() <= 5));
   JNIEnv* const env = mozilla::jni::GetEnvForThread();
   MOZ_ASSERT(env);
@@ -1586,12 +1580,10 @@ void AndroidProcessLauncher::LaunchAndroidService(
     crashAnnotationFd = fds_to_remap[4].first;
   }
 
-  int32_t handle = java::GeckoProcessManager::Start(
+  auto genericResult = java::GeckoProcessManager::Start(
       type, jargs, prefsFd, prefMapFd, ipcFd, crashFd, crashAnnotationFd);
-
-  if (process_handle) {
-    *process_handle = handle;
-  }
+  auto typedResult = java::GeckoResult::LocalRef(std::move(genericResult));
+  return ProcessHandlePromise::FromGeckoResult(typedResult);
 }
 #endif
 

mobile/android/geckoview/src/main/java/org/mozilla/gecko/process/GeckoProcessManager.java

@@ -11,6 +11,8 @@ import org.mozilla.gecko.IGeckoEditableParent;
 import org.mozilla.gecko.annotation.WrapForJNI;
 import org.mozilla.gecko.util.ThreadUtils;
 
+import org.mozilla.geckoview.GeckoResult;
+
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
@@ -207,11 +209,18 @@ public final class GeckoProcessManager extends IProcessManager.Stub {
     }
 
     @WrapForJNI
-    private static int start(final String type, final String[] args,
+    private static GeckoResult<Integer> start(final String type, final String[] args,
                              final int prefsFd, final int prefMapFd,
                              final int ipcFd,
                              final int crashFd, final int crashAnnotationFd) {
-        return INSTANCE.start(type, args, prefsFd, prefMapFd, ipcFd, crashFd, crashAnnotationFd, /* retry */ false);
+        int pid = INSTANCE.start(type, args, prefsFd, prefMapFd, ipcFd, crashFd, crashAnnotationFd, /* retry */ false);
+        GeckoResult<Integer> result = new GeckoResult<>();
+        if (pid == 0) {
+            result.completeExceptionally(new RuntimeException("Failed to start process"));
+        } else {
+            result.complete(pid);
+        }
+        return result;
     }
 
     private int filterFlagsForChild(final int flags) {

mobile/android/geckoview/src/main/java/org/mozilla/geckoview/GeckoResult.java

@@ -1,6 +1,7 @@
 package org.mozilla.geckoview;
 
 import org.mozilla.gecko.annotation.WrapForJNI;
+import org.mozilla.gecko.mozglue.JNIObject;
 import org.mozilla.gecko.util.ThreadUtils;
 
 import android.os.Handler;
@@ -463,6 +464,25 @@ public class GeckoResult<T> {
         }
     }
 
+    @WrapForJNI
+    private void nativeThen(@NonNull final GeckoCallback accept, @NonNull final GeckoCallback reject) {
+        // NB: We could use the lambda syntax here, but given all the layers
+        // of abstraction it's helpful to see the types written explicitly.
+        thenInternal(DirectDispatcher.sInstance, new OnValueListener<T, Void>() {
+            @Override
+            public GeckoResult<Void> onValue(final T value) {
+                accept.call(value);
+                return null;
+            }
+        }, new OnExceptionListener<Void>() {
+            @Override
+            public GeckoResult<Void> onException(final Throwable exception) {
+                reject.call(exception);
+                return null;
+            }
+        });
+    }
+
     /**
      * @return Get the {@link Looper} that will be used to schedule listeners registered via
      *         {@link #then(OnValueListener, OnExceptionListener)}.
@@ -683,6 +703,15 @@ public class GeckoResult<T> {
         @Nullable GeckoResult<V> onException(@NonNull Throwable exception) throws Throwable;
     }
 
+    @WrapForJNI
+    private static class GeckoCallback extends JNIObject {
+        private native void call(Object arg);
+
+        @Override
+        protected native void disposeNative();
+    }
+
+
     private boolean haveValue() {
         return mComplete && mError == null;
     }

widget/android/jni/Conversions.cpp

@@ -7,6 +7,8 @@
 #include "Conversions.h"
 #include "JavaBuiltins.h"
 
+#include "mozilla/ipc/GeckoChildProcessHost.h"
+
 namespace mozilla {
 namespace jni {
 
@@ -87,5 +89,10 @@ double Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
   return result;
 }
 
+template <>
+ipc::LaunchError Java2Native(mozilla::jni::Object::Param aData, JNIEnv* aEnv) {
+  return ipc::LaunchError{};
+}
+
 }  // namespace jni
 }  // namespace mozilla

widget/android/jni/GeckoResultUtils.h

@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_jni_GeckoResultUtils_h
+#define mozilla_jni_GeckoResultUtils_h
+
+#include "mozilla/jni/Conversions.h"
+#include "GeneratedJNIWrappers.h"
+#include "GeneratedJNINatives.h"
+
+namespace mozilla {
+namespace jni {
+
+// C++-side object bound to Java's GeckoResult.GeckoCallback.
+//
+// Note that we can't template this class because that breaks JNI dispatch
+// (surprisingly: it compiles, but selects the wrong method specialization
+// during dispatch). So instead we use a templated factory function, which
+// bundles the per-ArgType conversion logic into the callback.
+class GeckoResultCallback final
+    : public java::GeckoResult::GeckoCallback::Natives<GeckoResultCallback> {
+ public:
+  typedef java::GeckoResult::GeckoCallback::Natives<GeckoResultCallback> Base;
+  typedef std::function<void(mozilla::jni::Object::Param)> OuterCallback;
+
+  void Call(mozilla::jni::Object::Param aArg) { mCallback(aArg); }
+
+  template <typename ArgType>
+  static java::GeckoResult::GeckoCallback::LocalRef CreateAndAttach(
+      std::function<void(ArgType)>&& aInnerCallback) {
+    auto java = java::GeckoResult::GeckoCallback::New();
+    OuterCallback outerCallback =
+        [inner{std::move(aInnerCallback)}](mozilla::jni::Object::Param aParam) {
+          ArgType converted = Java2Native<ArgType>(aParam);
+          inner(converted);
+        };
+    auto native = MakeUnique<GeckoResultCallback>(std::move(outerCallback));
+    Base::AttachNative(java, std::move(native));
+    return java;
+  }
+
+  explicit GeckoResultCallback(OuterCallback&& aCallback)
+      : mCallback(std::move(aCallback)) {}
+
+ private:
+  OuterCallback mCallback;
+};
+
+}  // namespace jni
+}  // namespace mozilla
+
+#endif  // mozilla_jni_GeckoResultUtils_h

widget/android/jni/moz.build

@@ -11,6 +11,7 @@ EXPORTS.mozilla.jni += [
     'Accessors.h',
     'Conversions.h',
     'GeckoBundleUtils.h',
+    'GeckoResultUtils.h',
     'Natives.h',
     'Refs.h',
     'Types.h',

xpcom/threads/MozPromise.h

@@ -20,6 +20,10 @@
 #  include "nsTArray.h"
 #  include "nsThreadUtils.h"
 
+#  ifdef MOZ_WIDGET_ANDROID
+#    include "mozilla/jni/GeckoResultUtils.h"
+#  endif
+
 #  if MOZ_DIAGNOSTIC_ASSERT_ENABLED
 #    define PROMISE_DEBUG
 #  endif
@@ -934,6 +938,21 @@ class MozPromise : public MozPromiseBase {
     }
   }
 
+#  ifdef MOZ_WIDGET_ANDROID
+  // Creates a C++ MozPromise from its Java counterpart, GeckoResult.
+  static RefPtr<MozPromise> FromGeckoResult(
+      java::GeckoResult::Param aGeckoResult) {
+    using jni::GeckoResultCallback;
+    RefPtr<Private> p = new Private("GeckoResult Glue", false);
+    auto resolve = GeckoResultCallback::CreateAndAttach<ResolveValueType>(
+        [p](ResolveValueType aArg) { p->Resolve(aArg, __func__); });
+    auto reject = GeckoResultCallback::CreateAndAttach<RejectValueType>(
+        [p](RejectValueType aArg) { p->Reject(aArg, __func__); });
+    aGeckoResult->NativeThen(resolve, reject);
+    return p;
+  }
+#  endif
+
   // Note we expose the function AssertIsDead() instead of IsDead() since
   // checking IsDead() is a data race in the situation where the request is not
   // dead. Therefore we enforce the form |Assert(IsDead())| by exposing