libs\ — общая библиотека для всех модов

Загрузчик игры даёт каждому моду свой class loader, поэтому моды не видят друг
друга напрямую. Но у всех этих загрузчиков родителем является системный, а
значит всё, что добавлено в его classpath, видно каждому моду.

Агент теперь на старте дописывает все jar из <home>\libs\ в системный
classpath. Одна копия библиотеки на всех, модам не нужно ничего вшивать в себя.

Проверено стендом: библиотека testlib лежит в libs\, мод её использует, и в
jar мода её нет.

bridge/src/main/java/rsx/RsxAgent.java

@@ -47,6 +47,8 @@ public final class RsxAgent {
         Resolver.setInstrumentation(inst);
         Log.info("rsx bridge starting (home=" + home + ")");
 
+        appendLibraries(inst, new File(home, "libs"));
+
         String mode = readMode();
         if ("vanilla".equals(mode)) {
             Log.info("mode is vanilla: no mods, no patches, agent does nothing");
@@ -488,6 +490,40 @@ public final class RsxAgent {
     }
 
     // ----------------------------------------------------------------- utils
+
+    /**
+     * Put every jar from libs\ on the system class path.
+     *
+     * The client gives each mod its own class loader, so mods cannot see each
+     * other - but every one of those loaders has the system loader as its
+     * parent. Appending here therefore makes a shared library visible to all
+     * mods, in one copy, and mods never have to bundle it.
+     */
+    private static void appendLibraries(
+            java.lang.instrument.Instrumentation inst, File dir) {
+        if (inst == null || dir == null || !dir.isDirectory()) {
+            return;
+        }
+        File[] jars = dir.listFiles();
+        if (jars == null || jars.length == 0) {
+            Log.info("no libraries in " + dir);
+            return;
+        }
+        java.util.Arrays.sort(jars);
+        for (File jar : jars) {
+            if (!jar.isFile()
+                    || !jar.getName().toLowerCase().endsWith(".jar")) {
+                continue;
+            }
+            try {
+                inst.appendToSystemClassLoaderSearch(new java.util.jar.JarFile(jar));
+                Log.info("library on the class path: " + jar.getName());
+            } catch (Throwable t) {
+                Log.error("cannot load library " + jar.getName(), t);
+            }
+        }
+    }
+
     private static File findGameJar() {
         String loader = profile.loaderClass;
         if (loader == null) {

bridge/src/test/fakeclient/lib/rsxtest/testlib.java

@@ -0,0 +1,22 @@
+package rsxtest;
+
+// Test stand-in for a shared library that lives in libs\ and is appended to the
+// system class path. Every mod sees this class through its loader's parent, so
+// one copy serves all of them - which is the whole point of the libs\ folder.
+
+public final class testlib {
+
+    private static int calls;
+
+    private testlib() {
+    }
+
+    public static String greet(String who) {
+        calls++;
+        return "hello " + who;
+    }
+
+    public static int calls() {
+        return calls;
+    }
+}

bridge/src/test/mod/ThirdMod.java

@@ -2,6 +2,7 @@ package example;
 
 import net.rustexremake.api.Rsx;
 import net.rustexremake.api.RsxMod;
+import rsxtest.testlib;
 
 /**
  * Third and last mod: the one whose getRunnableList() the vendor actually keeps,
@@ -14,6 +15,9 @@ public class ThirdMod implements RsxMod {
     @Override
     public void onLoad() {
         Rsx.info("ThirdMod: loaded, this is the drain the vendor keeps");
+        // testlib lives in libs\ and is appended to the system class path, so it
+        // is visible here without being bundled into this mod's jar
+        Rsx.info("ThirdMod sees the library: " + testlib.greet("third"));
         Rsx.everyTicks(1, new Runnable() {
             @Override
             public void run() {

bridge/src/test/python/run_test.py

@@ -79,6 +79,10 @@ def javac(sources, out, cp=None):
         raise SystemExit("javac failed")
 
 
+def bridge_dir():
+    return os.path.join(RUN, "bridge")
+
+
 def zip_dir(src, jar):
     if os.path.exists(jar):
         os.remove(jar)
@@ -132,9 +136,21 @@ def main():
     javac([os.path.join(SRC, f) for f in os.listdir(SRC) if f.endswith(".java")],
           classes)
 
+    # the shared library lives in libs\ and is appended to the system class path
+    libdir = os.path.join(bridge_dir(), "libs")
+    shutil.rmtree(libdir, ignore_errors=True)
+    os.makedirs(libdir, exist_ok=True)
+    libclasses = os.path.join(RUN, "libclasses")
+    shutil.rmtree(libclasses, ignore_errors=True)
+    javac([os.path.join(SRC, "lib", "rsxtest", "testlib.java")], libclasses)
+    zip_dir(libclasses, os.path.join(libdir, "testlib.jar"))
+
     print("== compiling the mods ==")
+    # mods compile against the API and the shared library, but package neither:
+    # the library is on the system class path at runtime
     javac([os.path.join(MOD_SRC, f) for f in os.listdir(MOD_SRC)
-           if f.endswith(".java")], MOD_CLASSES, cp=BRIDGE_JAR)
+           if f.endswith(".java")], MOD_CLASSES,
+          cp=BRIDGE_JAR + os.pathsep + libclasses)
 
     game = os.path.join(RUN, "game.jar")
     zip_dir(classes, game)
@@ -218,6 +234,10 @@ def main():
         ("first mod loaded", "mod loaded: example-mod.jar" in out),
         ("second mod loaded", "mod loaded: second-mod.jar" in out),
         ("third mod loaded", "mod loaded: third-mod.jar" in out),
+        ("mod sees the shared library",
+         "ThirdMod sees the library: hello third" in out),
+        ("library was appended to the class path",
+         "library on the class path: testlib.jar" in out),
         ("mod 1 work runs", "ExampleMod tick 1" in out),
         ("mod 2 work runs (not the kept drain)",
          "SecondMod run 1" in out),