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dgantdgant
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Reduce startup work by binding only required Kernel32 functions
1 parent 51a03de commit f8e3abf

3 files changed

Lines changed: 108 additions & 5 deletions

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‎.github/workflows/maven.yml‎

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@@ -30,3 +30,25 @@ jobs:
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run: mvn -B package --file pom.xml
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- name: Test with Maven
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run: mvn test
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windows-java8-x86:
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name: Windows Java 8 x86
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runs-on: windows-latest
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steps:
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- uses: actions/checkout@v5
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- name: Set up the primary bot runtime
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uses: actions/setup-java@v5
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with:
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distribution: 'temurin'
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java-version: '8'
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architecture: 'x86'
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- name: Verify 32-bit Java 8
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shell: pwsh
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run: |
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$settings = (& java -XshowSettings:properties -version 2>&1 | Out-String)
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if ($settings -notmatch 'sun.arch.data.model\s*=\s*32' -or $settings -notmatch 'java.specification.version\s*=\s*1\.8') {
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throw 'Expected a 32-bit Java 8 JVM'
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}
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java -version
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- name: Build and test with Maven
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run: mvn -B package --file pom.xml

‎src/main/java/bwapi/ClientConnectionW32.java‎

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Original file line numberDiff line numberDiff line change
@@ -2,7 +2,8 @@
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import com.sun.jna.Native;
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import com.sun.jna.Pointer;
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import com.sun.jna.platform.win32.Kernel32;
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import com.sun.jna.platform.win32.WinNT.HANDLE;
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import com.sun.jna.win32.StdCallLibrary;
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import com.sun.jna.win32.W32APIOptions;
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import java.io.FileNotFoundException;
@@ -15,10 +16,19 @@
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class ClientConnectionW32 implements ClientConnection {
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private static final int READ_WRITE = 0x1 | 0x2 | 0x4;
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interface MappingKernel extends Kernel32 {
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MappingKernel INSTANCE = Native.load(MappingKernel.class, W32APIOptions.DEFAULT_OPTIONS);
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/**
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* Opens the BWAPI server's game table and game-state shared-memory mappings.
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* Binding only these two kernel32 functions avoids initializing JNA's full
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* Kernel32 proxy before the client can discover a server.
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* Measured savings: about 7% of startup time on Windows/Java 8 x86
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* with JNA 5.18.1 in fresh-JVM startup tests; actual savings depend on the machine.
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*/
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interface MappingKernel extends StdCallLibrary {
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MappingKernel INSTANCE = Native.load("kernel32", MappingKernel.class, W32APIOptions.DEFAULT_OPTIONS);
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HANDLE OpenFileMapping(int desiredAccess, boolean inherit, String name);
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Pointer MapViewOfFile(HANDLE mapping, int desiredAccess, int offsetHigh, int offsetLow, int bytesToMap);
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}
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@@ -38,7 +48,7 @@ public void disconnect() {
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@Override
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public WrappedBuffer getGameTable() {
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final Pointer gameTableView = Kernel32.INSTANCE.MapViewOfFile(MappingKernel.INSTANCE
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final Pointer gameTableView = MappingKernel.INSTANCE.MapViewOfFile(MappingKernel.INSTANCE
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.OpenFileMapping(READ_WRITE, false, "Local\\bwapi_shared_memory_game_list"), READ_WRITE,
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0, 0, GameTable.SIZE);
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return new WrappedBuffer(gameTableView, GameTable.SIZE);
@@ -48,7 +58,7 @@ public WrappedBuffer getGameTable() {
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public WrappedBuffer getSharedMemory(int serverProcID) {
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String sharedMemoryName = "Local\\bwapi_shared_memory_" + serverProcID;
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try {
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final Pointer mapFileView = Kernel32.INSTANCE.MapViewOfFile(MappingKernel.INSTANCE
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final Pointer mapFileView = MappingKernel.INSTANCE.MapViewOfFile(MappingKernel.INSTANCE
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.OpenFileMapping(READ_WRITE, false, sharedMemoryName), READ_WRITE,
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0, 0, ClientData.GameData.SIZE);
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return new WrappedBuffer(mapFileView, ClientData.GameData.SIZE);

‎src/test/java/bwapi/MappingKernelTest.java‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,71 @@
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package bwapi;
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import com.sun.jna.Pointer;
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import com.sun.jna.platform.win32.Kernel32;
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import com.sun.jna.platform.win32.WinBase;
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import com.sun.jna.platform.win32.WinNT;
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import org.junit.Before;
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import org.junit.Test;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertNotNull;
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import static org.junit.Assert.assertNull;
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import static org.junit.Assume.assumeTrue;
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/**
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* Verifies the Windows mapping binding's JNA signatures against a real shared-memory object.
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* The existing JNA Kernel32 binding creates the mapping and its first view;
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* MappingKernel opens a second view. Reads and writes must agree in both directions.
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* A Unicode name checks Windows string marshalling, and a missing mapping must
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* return null. These tests require Windows but do not require a BWAPI server.
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*/
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public class MappingKernelTest {
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@Before
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public void requireWindows() {
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assumeTrue(System.getProperty("os.name").startsWith("Windows"));
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}
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@Test
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public void opensUnicodeNamedMappingAndSharesWritesBetweenViews() {
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// Include Unicode to exercise the same W32API string mapping used by the client.
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String name = "Local\\jbwapi-mapping-\u03bb-" + System.nanoTime();
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int access = WinNT.SECTION_MAP_READ | WinNT.SECTION_MAP_WRITE;
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WinNT.HANDLE created = Kernel32.INSTANCE.CreateFileMapping(
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WinBase.INVALID_HANDLE_VALUE, null, WinNT.PAGE_READWRITE, 0, 4, name);
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assertNotNull(created);
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WinNT.HANDLE opened = null;
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Pointer originalView = null;
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Pointer clientView = null;
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try {
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originalView = Kernel32.INSTANCE.MapViewOfFile(created, access, 0, 0, 4);
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assertNotNull(originalView);
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originalView.setInt(0, 10003);
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opened = ClientConnectionW32.MappingKernel.INSTANCE.OpenFileMapping(access, false, name);
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assertNotNull(opened);
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clientView = ClientConnectionW32.MappingKernel.INSTANCE.MapViewOfFile(opened, access, 0, 0, 4);
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assertNotNull(clientView);
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assertEquals(10003, clientView.getInt(0));
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clientView.setInt(0, 42);
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assertEquals(42, originalView.getInt(0));
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} finally {
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if (clientView != null) {
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Kernel32.INSTANCE.UnmapViewOfFile(clientView);
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}
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if (originalView != null) {
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Kernel32.INSTANCE.UnmapViewOfFile(originalView);
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}
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if (opened != null) {
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Kernel32.INSTANCE.CloseHandle(opened);
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}
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Kernel32.INSTANCE.CloseHandle(created);
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}
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}
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@Test
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public void returnsNullForMissingMapping() {
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assertNull(ClientConnectionW32.MappingKernel.INSTANCE.OpenFileMapping(
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WinNT.SECTION_MAP_READ, false, "Local\\jbwapi-missing-" + System.nanoTime()));
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}
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}

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