[Java.Runtime.Environment] Add Java.Runtime.Environment.

Android preparation!

Android doesn't support JNI_CreateJavaVM(), JNI_GetCreatedJavaVMs(),
or any other JNI_*() export, so having anything that relies on these
JVM features will likely result in pain & suffering when we try to get
this all running under Dalvik/ART.

Add the Java.Runtime.Environment.dll assembly with the new
Java.Interop.JreVM type, and move the JNI_* functionality there.
Refactor/simplify Java.Interop.dll/Java.Interop.JavaVM to remove the
use of this functionality (e.g. rename JavaVM.GetCreatedJavaVMs() to
JavaVM.GetRegisteredJavaVM()).

The (unfortunate) result of all this is that Java.Interop.dll is no
longer usable by itself; it needs to be used in conjunction with
Java.Runtime.Environment.dll in order to create a Java VM.

Author: jonpryor

Java.Interop.sln

@@ -9,12 +9,18 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Java.Interop-Tests", "src\J
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Hello", "samples\Hello\Hello.csproj", "{F3ECB73D-9263-4E42-A5B4-3FC0D1D829F9}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Java.Runtime.Environment", "src\Java.Runtime.Environment\Java.Runtime.Environment.csproj", "{5887B410-D448-4257-A46B-EAC03C80BE93}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
 		Release|Any CPU = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{5887B410-D448-4257-A46B-EAC03C80BE93}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5887B410-D448-4257-A46B-EAC03C80BE93}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5887B410-D448-4257-A46B-EAC03C80BE93}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5887B410-D448-4257-A46B-EAC03C80BE93}.Release|Any CPU.Build.0 = Release|Any CPU
 		{6410DA0F-5E14-4FC0-9AEE-F4C542C96C7A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{6410DA0F-5E14-4FC0-9AEE-F4C542C96C7A}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{6410DA0F-5E14-4FC0-9AEE-F4C542C96C7A}.Release|Any CPU.ActiveCfg = Release|Any CPU

samples/Hello/Hello.csproj

@@ -42,5 +42,9 @@
       <Project>{94BD81F7-B06F-4295-9636-F8A3B6BDC762}</Project>
       <Name>Java.Interop</Name>
     </ProjectReference>
+    <ProjectReference Include="..\..\src\Java.Runtime.Environment\Java.Runtime.Environment.csproj">
+      <Project>{5887B410-D448-4257-A46B-EAC03C80BE93}</Project>
+      <Name>Java.Runtime.Environment</Name>
+    </ProjectReference>
   </ItemGroup>
 </Project>

samples/Hello/Program.cs

@@ -15,11 +15,11 @@ public static void Main (string[] args)
 			} catch (InvalidOperationException e) {
 				Console.WriteLine (e);
 			}
-			foreach (var h in JavaVM.GetCreatedJavaVMs ()) {
-				Console.WriteLine ("PRE: GetCreatedJavaVMs: {0}", h);
+			foreach (var h in JreVM.GetCreatedJavaVMHandles ()) {
+				Console.WriteLine ("PRE: GetCreatedJavaVMHandles: {0}", h);
 			}
 			Console.WriteLine ("Part 2!");
-			using (var vm = new JavaVMBuilder ().CreateJavaVM ()) {
+			using (var vm = new JreVMBuilder ().CreateJreVM ()) {
 				Console.WriteLine ("# JniEnvironment.Current={0}", JniEnvironment.Current);
 				Console.WriteLine ("vm.SafeHandle={0}", vm.SafeHandle);
 				var t = new JniType ("java/lang/Object");
@@ -43,12 +43,12 @@ public static void Main (string[] args)
 				t.Start ();
 				waitForCreation.Wait ();
 				*/
-				foreach (var h in JavaVM.GetCreatedJavaVMs ()) {
+				foreach (var h in JreVM.GetCreatedJavaVMHandles ()) {
 					Console.WriteLine ("WITHIN: GetCreatedJavaVMs: {0}", h);
 				}
 				// exitThread.Signal ();
 			}
-			foreach (var h in JavaVM.GetCreatedJavaVMs ()) {
+			foreach (var h in JreVM.GetCreatedJavaVMHandles ()) {
 				Console.WriteLine ("POST: GetCreatedJavaVMs: {0}", h);
 			}
 		}

src/Java.Interop/Java.Interop/JavaVM.cs

@@ -39,27 +39,14 @@ struct JavaVMThreadAttachArgs {
 		public  IntPtr              group;      /*		 global ref of a ThreadGroup object, or NULL */
 	}
 
-	struct JavaVMOption {
-		public  IntPtr /* const char * */   optionString;
-		public  IntPtr /* void * */         extraInfo;
-	}
-
-	struct JavaVMInitArgs {
-		public  JniVersion                      version;    /*		 use JNI_VERSION_1_2 or later */
-
-		public  int                             nOptions;
-		public  IntPtr /* JavaVMOption[] */     options;
-		public  byte                            ignoreUnrecognized;
-	}
-
 	public sealed class JavaVMSafeHandle : SafeHandle {
 
 		JavaVMSafeHandle ()
 			: base (IntPtr.Zero, ownsHandle:false)
 		{
 		}
 
-		internal JavaVMSafeHandle (IntPtr handle)
+		public JavaVMSafeHandle (IntPtr handle)
 			: this ()
 		{
 			SetHandle (handle);
@@ -90,52 +77,36 @@ public override string ToString ()
 		}
 	}
 
-	public sealed class JavaVMBuilder {
-
-		internal    List<string>    Options = new List<string> ();
+	public class JavaVMOptions {
 
-		public  JniVersion  JniVersion                  {get; set;}
-		public  bool        IgnoreUnrecognizedOptions   {get; set;}
 		public  bool        TrackIDs                    {get; set;}
+		public  bool        DestroyVMOnDispose          {get; set;}
 
-		public JavaVMBuilder ()
-		{
-			JniVersion  = JniVersion.v1_2;
-		}
-
-		public JavaVMBuilder AddOption (string option)
-		{
-			Options.Add (option);
-			return this;
-		}
-
-		public JavaVMBuilder AddSystemProperty (string name, string value)
-		{
-			if (name == null)
-				throw new ArgumentNullException ("name");
-			if (value == null)
-				throw new ArgumentNullException ("value");
-			Options.Add (string.Format ("-D{0}={1}", name, value));
-			return this;
-		}
+		public  JavaVMSafeHandle            VMHandle            {get; set;}
+		public  JniEnvironmentSafeHandle    EnvironmentHandle   {get; set;}
 
-		public JavaVM CreateJavaVM ()
+		public JavaVMOptions ()
 		{
-			return new JavaVM (this);
 		}
 	}
 
-	public partial class JavaVM : IDisposable
+	public abstract partial class JavaVM : IDisposable
 	{
-		const string LibraryName = "/System/Library/Frameworks/JavaVM.framework/JavaVM";
 
-		[DllImport (LibraryName)]
-		static extern int JNI_CreateJavaVM (out JavaVMSafeHandle javavm, out JniEnvironmentSafeHandle jnienv, ref JavaVMInitArgs args);
+		static ConcurrentDictionary<IntPtr, JavaVM>     JavaVMs = new ConcurrentDictionary<IntPtr, JavaVM> ();
 
-		[DllImport (LibraryName)]
-		static extern int JNI_GetCreatedJavaVMs ([Out] IntPtr[] handles, int bufLen, out int nVMs);
+		public static IEnumerable<JavaVM> GetRegisteredJavaVMs ()
+		{
+			return JavaVMs.Values;
+		}
 
-		static ConcurrentDictionary<IntPtr, JavaVM>     JavaVMs = new ConcurrentDictionary<IntPtr, JavaVM> ();
+		public static JavaVM GetRegisteredJavaVM (JavaVMSafeHandle handle)
+		{
+			JavaVM vm;
+			return JavaVMs.TryGetValue (handle.DangerousGetHandle (), out vm)
+				? vm
+				: null;
+		}
 
 		static JavaVM current;
 		public static JavaVM Current {
@@ -144,12 +115,12 @@ public static JavaVM Current {
 					return current;
 				JavaVM  c       = null;
 				int     count   = 0;
-				foreach (var vm in GetCreatedJavaVMs ()) {
+				foreach (var vm in JavaVMs.Values) {
 					if (count++ == 0)
 						c = vm;
 				}
 				if (count == 0)
-					throw new InvalidOperationException ("No JavaVM has been created. Please use JavaVMBuilder.CreateJavaVM().");
+					throw new InvalidOperationException ("No JavaVM has been created. Please use Java.Interop.JreVMBuilder.CreateJreVM().");
 				if (count > 1)
 					throw new NotSupportedException (string.Format ("Found {0} JavaVMs. Don't know which to use. Use JavaVM.SetCurrent().", count));
 				return current = c;
@@ -160,52 +131,10 @@ public static void SetCurrent (JavaVM newCurrent)
 		{
 			if (newCurrent == null)
 				throw new ArgumentNullException ("newCurrent");
+			JavaVMs.TryAdd (newCurrent.SafeHandle.DangerousGetHandle (), newCurrent);
 			current = newCurrent;
 		}
 
-		public static IEnumerable<JavaVM> GetCreatedJavaVMs ()
-		{
-			int nVMs;
-			int r = JNI_GetCreatedJavaVMs (null, 0, out nVMs);
-			if (r != 0)
-				throw new NotSupportedException ("JNI_GetCreatedJavaVMs() returned: " + r);
-			var handles = new IntPtr [nVMs];
-			r = JNI_GetCreatedJavaVMs (handles, handles.Length, out nVMs);
-			if (r != 0)
-				throw new InvalidOperationException ("JNI_GetCreatedJavaVMs() [take 2!] returned: " + r);
-			foreach (var h in handles) {
-				JavaVM v;
-				if (!JavaVMs.TryGetValue (h, out v))
-					JavaVMs.TryAdd (h, v = new JavaVM (new JavaVMSafeHandle (h)));
-				yield return v;
-			}
-		}
-
-		public static JavaVM FromHandle (JavaVMSafeHandle handle)
-		{
-			JavaVM vm;
-			if (JavaVMs.TryGetValue (handle.DangerousGetHandle (), out vm))
-				return vm;
-			return new JavaVM (handle, null);
-		}
-
-		void CreateJavaVM (ref JavaVMInitArgs args)
-		{
-			JavaVMSafeHandle            javavm;
-			JniEnvironmentSafeHandle    jnienv;
-			int r = JNI_CreateJavaVM (out javavm, out jnienv, ref args);
-			if (r != 0) {
-				var message = string.Format ("{1}JNI_CreateJavaVM returned {0}.",
-						r,
-						JavaVMs.Count == 0
-							? ""
-							: "The JDK supports creating at most one JVM per process, ever; " +
-							  "do you have a JVM running already, or have you already created (and destroyed?) one? ");
-				throw new NotSupportedException (message);
-			}
-			Initialize (javavm, jnienv);
-		}
-
 		ConcurrentDictionary<IntPtr, JniEnvironment>    Environments = new ConcurrentDictionary<IntPtr, JniEnvironment> ();
 
 		ConcurrentDictionary<SafeHandle, IDisposable>   TrackedInstances;
@@ -219,58 +148,26 @@ void CreateJavaVM (ref JavaVMInitArgs args)
 
 		public  JavaVMSafeHandle                        SafeHandle      {get; private set;}
 
-		protected JavaVM ()
-			: this (new JavaVMBuilder ())
+		protected JavaVM (JavaVMOptions options)
 		{
-		}
-
-		internal protected unsafe JavaVM (JavaVMBuilder builder)
-		{
-			if (builder == null)
-				throw new ArgumentNullException ("builder");
-
-			var args = new JavaVMInitArgs () {
-				version             = builder.JniVersion,
-				nOptions            = builder.Options.Count,
-				ignoreUnrecognized  = builder.IgnoreUnrecognizedOptions ? (byte) 1 : (byte) 0,
-			};
-			var options = new JavaVMOption [builder.Options.Count];
-			try {
-				for (int i = 0; i < options.Length; ++i)
-					options [i].optionString = Marshal.StringToHGlobalAnsi (builder.Options [i]);
-				fixed (JavaVMOption* popts = options) {
-					args.options = (IntPtr) popts;
-					CreateJavaVM (ref args);
-				}
-			} finally {
-				for (int i = 0; i < options.Length; ++i)
-					Marshal.FreeHGlobal (options [i].optionString);
-			}
+			if (options == null)
+				throw new ArgumentNullException ("options");
+			if (options.VMHandle == null)
+				throw new ArgumentException ("options.VMHandle is null", "options");
+			if (options.VMHandle.IsInvalid)
+				throw new ArgumentException ("options.VMHandle is not valid.", "options");
 
-			TrackIDs    = builder.TrackIDs;
-			DestroyVM   = true;
-		}
+			TrackIDs     = options.TrackIDs;
+			DestroyVM    = options.DestroyVMOnDispose;
 
-		public JavaVM (JavaVMSafeHandle safeHandle, JniEnvironmentSafeHandle jnienv = null)
-		{
-			Initialize (safeHandle, jnienv);
-		}
-
-		void Initialize (JavaVMSafeHandle safeHandle, JniEnvironmentSafeHandle jnienv)
-		{
-			if (safeHandle == null)
-				throw new ArgumentNullException ("safeHandle");
-			if (safeHandle.IsInvalid)
-				throw new ArgumentException ("safeHandle is not valid.", "safeHandle");
+			SafeHandle  = options.VMHandle;
+			Invoker     = SafeHandle.CreateInvoker ();
 
 			if (current == null)
 				current = this;
 
-			SafeHandle  = safeHandle;
-			Invoker     = safeHandle.CreateInvoker ();
-
-			if (jnienv != null) {
-				var env = new JniEnvironment (jnienv, this);
+			if (options.EnvironmentHandle != null) {
+				var env = new JniEnvironment (options.EnvironmentHandle, this);
 				Environments.TryAdd (env.SafeHandle.DangerousGetHandle (), env);
 			}
 
@@ -301,10 +198,10 @@ protected virtual void Dispose (bool disposing)
 				current = null;
 
 			ClearTrackedReferences ();
-			if (DestroyVM)
-				DestroyJavaVM ();
 			JavaVM _;
 			JavaVMs.TryRemove (SafeHandle.DangerousGetHandle (), out _);
+			if (DestroyVM)
+				DestroyJavaVM ();
 			SafeHandle.Dispose ();
 			SafeHandle = null;
 		}

src/Java.Interop/Java.Interop/JniEnvironment.cs

@@ -82,7 +82,11 @@ public static JniEnvironment GetEnvironmentFromHandle (IntPtr handle)
 			int r = env.Invoker.GetJavaVM (env.SafeHandle, out vm);
 			if (r < 0)
 				throw new InvalidOperationException ("JNIEnv::GetJavaVM() returned: " + r);
-			env.JavaVM = JavaVM.FromHandle (vm);
+			env.JavaVM = JavaVM.GetRegisteredJavaVM (vm);
+			if (env.JavaVM == null)
+				throw new NotSupportedException (
+						string.Format ("No JavaVM registered with handle 0x{0}.",
+							vm.DangerousGetHandle ().ToString ("x")));
 			return env;
 		}
 
@@ -91,10 +95,12 @@ public void Dispose ()
 			if (SafeHandle == null)
 				return;
 			Object_class.Dispose ();
+			Object_toString.Dispose ();
 			if (Current == this)
 				current = null;
 			SafeHandle.Dispose ();
 			SafeHandle = null;
+			JavaVM     = null;
 		}
 
 		            JniType             Object_class;

src/Java.Interop/Tests/Java.Interop-Tests.csproj

@@ -81,5 +81,9 @@
       <Project>{94BD81F7-B06F-4295-9636-F8A3B6BDC762}</Project>
       <Name>Java.Interop</Name>
     </ProjectReference>
+    <ProjectReference Include="..\..\Java.Runtime.Environment\Java.Runtime.Environment.csproj">
+      <Project>{5887B410-D448-4257-A46B-EAC03C80BE93}</Project>
+      <Name>Java.Runtime.Environment</Name>
+    </ProjectReference>
   </ItemGroup>
 </Project>

src/Java.Interop/Tests/Java.Interop/JVM.cs

@@ -7,14 +7,14 @@
 
 namespace Java.InteropTests {
 
-	class JVM : JavaVM {
+	class JVM : JreVM {
 
 		public static readonly new JavaVM Current = new JVM ();
 
 		TextWriter  grefLog;
 
 		JVM ()
-			: base (new JavaVMBuilder ().AddSystemProperty ("java.class.path", "interop-test.jar"))
+			: base (new JreVMBuilder ().AddSystemProperty ("java.class.path", "interop-test.jar"))
 		{
 			string logGrefs = (Environment.GetEnvironmentVariable ("_JI_LOG") ?? "")
 				.Split (new []{ ',' }, StringSplitOptions.RemoveEmptyEntries)

src/Java.Interop/Tests/Java.Interop/JavaVMTest.cs

@@ -24,7 +24,7 @@ public void JDK_OnlySupportsOneVM ()
 			var first = JVM.Current;
 			#pragma warning restore 0219
 			try {
-				var second = new JavaVMBuilder ().CreateJavaVM ();
+				var second = new JreVMBuilder ().CreateJreVM ();
 				// If we reach here, we're in a JVM that supports > 1 VM
 				second.Dispose ();
 				Assert.Ignore ();
@@ -42,15 +42,15 @@ public void CreateJavaVMWithNullBuilder ()
 
 		class JavaVMWithNullBuilder : JavaVM {
 			public JavaVMWithNullBuilder ()
-				: base ((JavaVMBuilder) null)
+				: base ((JavaVMOptions) null)
 			{
 			}
 		}
 
 		[Test]
-		public void FromHandle_ExistingInstance ()
+		public void GetRegisteredJavaVM_ExistingInstance ()
 		{
-			Assert.AreEqual (JavaVM.Current, JavaVM.FromHandle (JavaVM.Current.SafeHandle));
+			Assert.AreEqual (JavaVM.Current, JavaVM.GetRegisteredJavaVM (JavaVM.Current.SafeHandle));
 		}
 
 		[Test]