Expose MemorySegment

Author: ShirasawaSama

README.md

@@ -61,11 +61,10 @@ main.cpp:
 #include <jshm.h>
 
 int main() {
-    auto shm = jshm::shared_memory::create("test", 1024);
-    // auto shm = jshm::shared_memory::open("test", 1024);
-    auto buf = (char*)shm;
-    strcpy(buf, "Hello, World!");
-    delete shm;
+	auto shm = jshm::shared_memory::create("test", 1024);
+	// auto shm = jshm::shared_memory::open("test", 1024);
+	strcpy((char*)shm->address(), "Hello, World!");
+	delete shm;
 }
 ```
 

build.gradle

@@ -4,7 +4,7 @@ plugins {
 }
 
 group 'cn.apisium.shm'
-version '1.0.0'
+version '0.0.1'
 
 sourceCompatibility = JavaVersion.VERSION_19
 targetCompatibility = JavaVersion.VERSION_19
@@ -30,6 +30,7 @@ publishing {
 }
 
 dependencies {
+    implementation 'org.jetbrains:annotations:24.0.0'
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.1'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.1'
 }

include/jshm.h

@@ -9,8 +9,8 @@
 namespace jshm {
 	class shared_memory {
 	public:
-		int size() { return _size; }
-		const char* name() { return _name; }
+		int size() const noexcept { return _size; }
+		const char* name() const noexcept { return _name; }
 
 		~shared_memory() {
 #ifdef _WIN32
@@ -19,7 +19,7 @@ namespace jshm {
 #endif
 		}
 
-		operator void* () {
+		void* address() const noexcept {
 #ifdef _WIN32
 			return pBuf;
 #endif

src/main/java/cn/apisium/shm/CABI.java

@@ -1,5 +1,7 @@
 package cn.apisium.shm;
 
+import org.jetbrains.annotations.NotNull;
+
 import static java.lang.foreign.ValueLayout.ADDRESS;
 
 public class CABI {
@@ -11,6 +13,7 @@ public enum SystemType { Unknown, Windows, Linux, MacOS }
     /**
      * The current system type.
      */
+    @NotNull
     public static final SystemType SYSTEM_TYPE;
 
     static {

src/main/java/cn/apisium/shm/SharedMemory.java

@@ -1,7 +1,10 @@
 package cn.apisium.shm;
 
 import cn.apisium.shm.impl.WindowsSharedMemory;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
 
+import java.lang.foreign.MemorySegment;
 import java.nio.ByteBuffer;
 
 /**
@@ -13,18 +16,31 @@ public interface SharedMemory extends AutoCloseable {
      * Get the shared memory as a {@link ByteBuffer}.
      * @return The shared memory as a {@link ByteBuffer}.
      */
+    @NotNull
+    @Contract(pure = true)
     ByteBuffer toByteBuffer();
 
+    /**
+     * Get the shared memory as a {@link MemorySegment}.
+     * @return The shared memory as a {@link MemorySegment}.
+     */
+    @NotNull
+    @Contract(pure = true)
+    MemorySegment getMemorySegment();
+
     /**
      * Get the size of the shared memory.
      * @return The size of the shared memory.
      */
+    @Contract(pure = true)
     int size();
 
     /**
      * Get the name of the shared memory.
      * @return The name of the shared memory.
      */
+    @NotNull
+    @Contract(pure = true)
     String getName();
 
     /**
@@ -33,7 +49,8 @@ public interface SharedMemory extends AutoCloseable {
      * @param size The size of the shared memory.
      * @return The shared memory.
      */
-    static SharedMemory open(String name, int size) {
+    @NotNull
+    static SharedMemory open(@NotNull String name, int size) {
         return init(name, size, false);
     }
 
@@ -43,19 +60,22 @@ static SharedMemory open(String name, int size) {
      * @param size The size of the shared memory.
      * @return The shared memory.
      */
-    static SharedMemory create(String name, int size) {
+    @NotNull
+    static SharedMemory create(@NotNull String name, int size) {
         return init(name, size, true);
     }
 
     /**
      * Check if the current system is supported.
      * @return If the current system is supported.
      */
+    @Contract(pure = true)
     static boolean isSupported() {
         return CABI.SYSTEM_TYPE == CABI.SystemType.Windows;
     }
 
-    private static SharedMemory init(String name, int size, boolean isCreate) {
+    @NotNull
+    private static SharedMemory init(@NotNull String name, int size, boolean isCreate) {
         try {
             return switch (CABI.SYSTEM_TYPE) {
                 case Windows -> new WindowsSharedMemory(name, size, isCreate);

src/main/java/cn/apisium/shm/impl/WindowsSharedMemory.java

@@ -2,6 +2,7 @@
 
 import cn.apisium.shm.CABI;
 import cn.apisium.shm.SharedMemory;
+import org.jetbrains.annotations.NotNull;
 
 import java.lang.foreign.*;
 import java.lang.invoke.MethodHandle;
@@ -59,7 +60,7 @@ public class WindowsSharedMemory implements SharedMemory {
     private final int size;
     private final String name;
     private final MemoryAddress hMapFile, pBuf;
-    private final ByteBuffer buffer;
+    private final MemorySegment segment;
 
     public WindowsSharedMemory(String name, int size) throws Throwable { this(name, size, true); }
     public WindowsSharedMemory(String name, int size, boolean isCreate) throws Throwable {
@@ -82,17 +83,20 @@ public WindowsSharedMemory(String name, int size, boolean isCreate) throws Throw
             closeHandle.invokeExact((Addressable) hMapFile);
             throw th;
         }
-        buffer = MemorySegment.ofAddress(pBuf, size, session).asByteBuffer();
+        segment = MemorySegment.ofAddress(pBuf, size, session);
     }
 
     @Override
-    public ByteBuffer toByteBuffer() { return buffer.duplicate(); }
+    public @NotNull MemorySegment getMemorySegment() { return segment; }
+
+    @Override
+    public @NotNull ByteBuffer toByteBuffer() { return segment.asByteBuffer(); }
 
     @Override
     public int size() { return size; }
 
     @Override
-    public String getName() { return name; }
+    public @NotNull String getName() { return name; }
 
     @Override
     public void close() throws Exception {