fix(java): compilation fails with "code too large" (#1605)

In cases where a module includes a large amount of types, compilation of Java packages could fail with the "code too large" error. This is due to the presence of a single method in the `$Module` class that contains a reference to all types in the package, resulting in a large amount of generated bytecode (more than Java's maximum of 64KB). In order to remediate, moved the FQN to Class mapping to a resource file that gets loaded when the `$Module` class is initialized. The individual `Class` entries are then resolved at the last minute using `Class.forName` to ensure the reoslution happens *after* the full mapping has been processed.
aws · Apr 22, 2020 · b9ec853 · b9ec853
1 parent fe58cc2
commit b9ec853
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Showing 9 changed files with 489 additions and 226 deletions.
diff --git a/packages/jsii-pacmak/lib/targets/java.ts b/packages/jsii-pacmak/lib/targets/java.ts
@@ -1544,6 +1544,20 @@ class JavaGenerator extends Generator {
     return `${path.join('src', 'main', 'java', ...packageName.split('.'), typeName.split('.')[0])}.java`;
   }
 
+  private toJavaResourcePath(assm: spec.Assembly, fqn: string, ext = '.txt') {
+    const { packageName, typeName } = this.toNativeName(assm, {
+      fqn,
+      kind: spec.TypeKind.Class,
+      assembly: assm.name,
+      name: fqn.replace(/.*\.([^.]+)$/, '$1')
+    });
+
+    const name = `${path.join(...packageName.split('.'), typeName.split('.')[0])}${ext}`;
+    const filePath = path.join('src', 'main', 'resources', name);
+
+    return { filePath, name };
+  }
+
   // eslint-disable-next-line complexity
   private addJavaDocs(doc: spec.Documentable, defaultText?: string) {
     if (!defaultText && Object.keys(doc.docs ?? {}).length === 0
@@ -1813,24 +1827,74 @@ class JavaGenerator extends Generator {
   private emitModuleFile(mod: spec.Assembly) {
     const moduleName = mod.name;
     const moduleClass = this.makeModuleClass(moduleName);
+
+    const { filePath: moduleResFile, name: moduleResName } = this.toJavaResourcePath(mod, `${mod.name}.${MODULE_CLASS_NAME}`);
+    this.code.openFile(moduleResFile);
+    for (const fqn of Object.keys(this.assembly.types ?? {})) {
+      this.code.line(`${fqn}=${this.toNativeFqn(fqn, { binaryName: true })}`);
+    }
+    this.code.closeFile(moduleResFile);
+
     const moduleFile = this.toJavaFilePath(mod, {
       assembly: mod.name,
       fqn: `${mod.name}.${MODULE_CLASS_NAME}`,
       kind: spec.TypeKind.Class,
       name: MODULE_CLASS_NAME,
     });
+
     this.code.openFile(moduleFile);
     this.code.line(`package ${this.toNativeName(mod).packageName};`);
     this.code.line();
     if (Object.keys(mod.dependencies ?? {}).length > 0) {
       this.code.line('import static java.util.Arrays.asList;');
       this.code.line();
+    }
+    this.code.line('import java.io.BufferedReader;');
+    this.code.line('import java.io.InputStream;');
+    this.code.line('import java.io.InputStreamReader;');
+    this.code.line('import java.io.IOException;');
+    this.code.line('import java.io.Reader;');
+    this.code.line('import java.io.UncheckedIOException;');
+    this.code.line();
+    this.code.line('import java.nio.charset.StandardCharsets;');
+    this.code.line();
+    this.code.line('import java.util.HashMap;');
+    if (Object.keys(mod.dependencies ?? {}).length > 0) {
       this.code.line('import java.util.List;');
     }
+    this.code.line('import java.util.Map;');
+    this.code.line();
     this.code.line('import software.amazon.jsii.JsiiModule;');
     this.code.line();
 
     this.code.openBlock(`public final class ${MODULE_CLASS_NAME} extends JsiiModule`);
+    this.code.line('private static final Map<String, String> MODULE_TYPES = load();');
+    this.code.line();
+
+    this.code.openBlock('private static Map<String, String> load()');
+    this.code.line('final Map<String, String> result = new HashMap<>();');
+    this.code.line(`final ClassLoader cl = ${MODULE_CLASS_NAME}.class.getClassLoader();`);
+    this.code.line(`try (final InputStream is = cl.getResourceAsStream("${moduleResName}");`);
+    this.code.line('     final Reader rd = new InputStreamReader(is, StandardCharsets.UTF_8);');
+    this.code.openBlock('     final BufferedReader br = new BufferedReader(rd))');
+    this.code.line('br.lines()');
+    this.code.line('  .filter(line -> !line.trim().isEmpty())');
+    this.code.openBlock('  .forEach(line -> ');
+    this.code.line('final String[] parts = line.split("=", 2);');
+    this.code.line('final String fqn = parts[0];');
+    this.code.line('final String className = parts[1];');
+    this.code.line('result.put(fqn, className);');
+    this.code.unindent('});'); // Proxy for closeBlock
+    this.code.closeBlock();
+    this.code.openBlock('catch (final IOException exception)');
+    this.code.line('throw new UncheckedIOException(exception);');
+    this.code.closeBlock();
+    this.code.line('return result;');
+    this.code.closeBlock();
+    this.code.line();
+
+    this.code.line('private final Map<String, Class<?>> cache = new HashMap<>();');
+    this.code.line();
 
     // ctor
     this.code.openBlock(`public ${MODULE_CLASS_NAME}()`);
@@ -1854,11 +1918,19 @@ class JavaGenerator extends Generator {
     this.code.line();
     this.code.line('@Override');
     this.code.openBlock('protected Class<?> resolveClass(final String fqn) throws ClassNotFoundException');
-    this.code.openBlock('switch (fqn)');
-    for (const type of Object.keys(this.assembly.types ?? {})) {
-      this.code.line(`case "${type}": return ${this.toNativeFqn(type)}.class;`);
-    }
-    this.code.line('default: throw new ClassNotFoundException("Unknown JSII type: " + fqn);');
+    this.code.openBlock('if (!MODULE_TYPES.containsKey(fqn))');
+    this.code.line('throw new ClassNotFoundException("Unknown JSII type: " + fqn);');
+    this.code.closeBlock();
+    this.code.line('return this.cache.computeIfAbsent(MODULE_TYPES.get(fqn), this::findClass);');
+    this.code.closeBlock();
+
+    this.code.line();
+    this.code.openBlock('private Class<?> findClass(final String binaryName)');
+    this.code.openBlock('try');
+    this.code.line('return Class.forName(binaryName);');
+    this.code.closeBlock();
+    this.code.openBlock('catch (final ClassNotFoundException exception)');
+    this.code.line('throw new RuntimeException(exception);');
     this.code.closeBlock();
     this.code.closeBlock();
 
@@ -1893,7 +1965,7 @@ class JavaGenerator extends Generator {
    *
    * @throws if the assembly the FQN belongs to does not have a `targets.java.package` set.
    */
-  private toNativeFqn(fqn: string): string {
+  private toNativeFqn(fqn: string, { binaryName }: { binaryName: boolean } = { binaryName: false }): string {
     const [mod, ...name] = fqn.split('.');
     const depMod = this.findModule(mod);
     // Make sure any dependency (direct or transitive) of which any type is explicitly referenced by the generated
@@ -1905,7 +1977,10 @@ class JavaGenerator extends Generator {
     }
 
     const { packageName, typeName } = this.toNativeName(this.assembly, this.assembly.types![fqn]);
-    return `${packageName}${typeName ? `.${typeName}` : ''}`;
+    const className = typeName && binaryName
+      ? typeName.replace('.', '$')
+      : typeName;
+    return `${packageName}${className ? `.${className}` : ''}`;
   }
 
   private getNativeName(assm: spec.Assembly, name: string | undefined): string;

diff --git a/...-of-base/java/src/main/java/software/amazon/jsii/tests/calculator/baseofbase/$Module.java b/...-of-base/java/src/main/java/software/amazon/jsii/tests/calculator/baseofbase/$Module.java
@@ -1,19 +1,63 @@
 package software.amazon.jsii.tests.calculator.baseofbase;
 
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.UncheckedIOException;
+
+import java.nio.charset.StandardCharsets;
+
+import java.util.HashMap;
+import java.util.Map;
+
 import software.amazon.jsii.JsiiModule;
 
 public final class $Module extends JsiiModule {
+    private static final Map<String, String> MODULE_TYPES = load();
+
+    private static Map<String, String> load() {
+        final Map<String, String> result = new HashMap<>();
+        final ClassLoader cl = $Module.class.getClassLoader();
+        try (final InputStream is = cl.getResourceAsStream("software/amazon/jsii/tests/calculator/baseofbase/$Module.txt");
+             final Reader rd = new InputStreamReader(is, StandardCharsets.UTF_8);
+             final BufferedReader br = new BufferedReader(rd)) {
+            br.lines()
+              .filter(line -> !line.trim().isEmpty())
+              .forEach(line ->  {
+                final String[] parts = line.split("=", 2);
+                final String fqn = parts[0];
+                final String className = parts[1];
+                result.put(fqn, className);
+            });
+        }
+        catch (final IOException exception) {
+            throw new UncheckedIOException(exception);
+        }
+        return result;
+    }
+
+    private final Map<String, Class<?>> cache = new HashMap<>();
+
     public $Module() {
         super("@scope/jsii-calc-base-of-base", "0.0.0", $Module.class, "jsii-calc-base-of-base@0.0.0.jsii.tgz");
     }
 
     @Override
     protected Class<?> resolveClass(final String fqn) throws ClassNotFoundException {
-        switch (fqn) {
-            case "@scope/jsii-calc-base-of-base.IVeryBaseInterface": return software.amazon.jsii.tests.calculator.baseofbase.IVeryBaseInterface.class;
-            case "@scope/jsii-calc-base-of-base.Very": return software.amazon.jsii.tests.calculator.baseofbase.Very.class;
-            case "@scope/jsii-calc-base-of-base.VeryBaseProps": return software.amazon.jsii.tests.calculator.baseofbase.VeryBaseProps.class;
-            default: throw new ClassNotFoundException("Unknown JSII type: " + fqn);
+        if (!MODULE_TYPES.containsKey(fqn)) {
+            throw new ClassNotFoundException("Unknown JSII type: " + fqn);
+        }
+        return this.cache.computeIfAbsent(MODULE_TYPES.get(fqn), this::findClass);
+    }
+
+    private Class<?> findClass(final String binaryName) {
+        try {
+            return Class.forName(binaryName);
+        }
+        catch (final ClassNotFoundException exception) {
+            throw new RuntimeException(exception);
         }
     }
 }
diff --git a/...base/java/src/main/resources/software/amazon/jsii/tests/calculator/baseofbase/$Module.txt b/...base/java/src/main/resources/software/amazon/jsii/tests/calculator/baseofbase/$Module.txt
@@ -0,0 +1,3 @@
+@scope/jsii-calc-base-of-base.IVeryBaseInterface=software.amazon.jsii.tests.calculator.baseofbase.IVeryBaseInterface
+@scope/jsii-calc-base-of-base.Very=software.amazon.jsii.tests.calculator.baseofbase.Very
+@scope/jsii-calc-base-of-base.VeryBaseProps=software.amazon.jsii.tests.calculator.baseofbase.VeryBaseProps
diff --git a/...jsii-calc-base/java/src/main/java/software/amazon/jsii/tests/calculator/base/$Module.java b/...jsii-calc-base/java/src/main/java/software/amazon/jsii/tests/calculator/base/$Module.java
@@ -2,10 +2,47 @@
 
 import static java.util.Arrays.asList;
 
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.UncheckedIOException;
+
+import java.nio.charset.StandardCharsets;
+
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+
 import software.amazon.jsii.JsiiModule;
 
 public final class $Module extends JsiiModule {
+    private static final Map<String, String> MODULE_TYPES = load();
+
+    private static Map<String, String> load() {
+        final Map<String, String> result = new HashMap<>();
+        final ClassLoader cl = $Module.class.getClassLoader();
+        try (final InputStream is = cl.getResourceAsStream("software/amazon/jsii/tests/calculator/base/$Module.txt");
+             final Reader rd = new InputStreamReader(is, StandardCharsets.UTF_8);
+             final BufferedReader br = new BufferedReader(rd)) {
+            br.lines()
+              .filter(line -> !line.trim().isEmpty())
+              .forEach(line ->  {
+                final String[] parts = line.split("=", 2);
+                final String fqn = parts[0];
+                final String className = parts[1];
+                result.put(fqn, className);
+            });
+        }
+        catch (final IOException exception) {
+            throw new UncheckedIOException(exception);
+        }
+        return result;
+    }
+
+    private final Map<String, Class<?>> cache = new HashMap<>();
+
     public $Module() {
         super("@scope/jsii-calc-base", "0.0.0", $Module.class, "jsii-calc-base@0.0.0.jsii.tgz");
     }
@@ -17,11 +54,18 @@ public List<Class<? extends JsiiModule>> getDependencies() {
 
     @Override
     protected Class<?> resolveClass(final String fqn) throws ClassNotFoundException {
-        switch (fqn) {
-            case "@scope/jsii-calc-base.Base": return software.amazon.jsii.tests.calculator.base.Base.class;
-            case "@scope/jsii-calc-base.BaseProps": return software.amazon.jsii.tests.calculator.base.BaseProps.class;
-            case "@scope/jsii-calc-base.IBaseInterface": return software.amazon.jsii.tests.calculator.base.IBaseInterface.class;
-            default: throw new ClassNotFoundException("Unknown JSII type: " + fqn);
+        if (!MODULE_TYPES.containsKey(fqn)) {
+            throw new ClassNotFoundException("Unknown JSII type: " + fqn);
+        }
+        return this.cache.computeIfAbsent(MODULE_TYPES.get(fqn), this::findClass);
+    }
+
+    private Class<?> findClass(final String binaryName) {
+        try {
+            return Class.forName(binaryName);
+        }
+        catch (final ClassNotFoundException exception) {
+            throw new RuntimeException(exception);
         }
     }
 }
diff --git a/...-calc-base/java/src/main/resources/software/amazon/jsii/tests/calculator/base/$Module.txt b/...-calc-base/java/src/main/resources/software/amazon/jsii/tests/calculator/base/$Module.txt
@@ -0,0 +1,3 @@
+@scope/jsii-calc-base.Base=software.amazon.jsii.tests.calculator.base.Base
+@scope/jsii-calc-base.BaseProps=software.amazon.jsii.tests.calculator.base.BaseProps
+@scope/jsii-calc-base.IBaseInterface=software.amazon.jsii.tests.calculator.base.IBaseInterface
diff --git a/...d.jsii-calc-lib/java/src/main/java/software/amazon/jsii/tests/calculator/lib/$Module.java b/...d.jsii-calc-lib/java/src/main/java/software/amazon/jsii/tests/calculator/lib/$Module.java
@@ -2,10 +2,47 @@
 
 import static java.util.Arrays.asList;
 
+import java.io.BufferedReader;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.Reader;
+import java.io.UncheckedIOException;
+
+import java.nio.charset.StandardCharsets;
+
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
+
 import software.amazon.jsii.JsiiModule;
 
 public final class $Module extends JsiiModule {
+    private static final Map<String, String> MODULE_TYPES = load();
+
+    private static Map<String, String> load() {
+        final Map<String, String> result = new HashMap<>();
+        final ClassLoader cl = $Module.class.getClassLoader();
+        try (final InputStream is = cl.getResourceAsStream("software/amazon/jsii/tests/calculator/lib/$Module.txt");
+             final Reader rd = new InputStreamReader(is, StandardCharsets.UTF_8);
+             final BufferedReader br = new BufferedReader(rd)) {
+            br.lines()
+              .filter(line -> !line.trim().isEmpty())
+              .forEach(line ->  {
+                final String[] parts = line.split("=", 2);
+                final String fqn = parts[0];
+                final String className = parts[1];
+                result.put(fqn, className);
+            });
+        }
+        catch (final IOException exception) {
+            throw new UncheckedIOException(exception);
+        }
+        return result;
+    }
+
+    private final Map<String, Class<?>> cache = new HashMap<>();
+
     public $Module() {
         super("@scope/jsii-calc-lib", "0.0.0", $Module.class, "jsii-calc-lib@0.0.0.jsii.tgz");
     }
@@ -17,17 +54,18 @@ public List<Class<? extends JsiiModule>> getDependencies() {
 
     @Override
     protected Class<?> resolveClass(final String fqn) throws ClassNotFoundException {
-        switch (fqn) {
-            case "@scope/jsii-calc-lib.EnumFromScopedModule": return software.amazon.jsii.tests.calculator.lib.EnumFromScopedModule.class;
-            case "@scope/jsii-calc-lib.IDoublable": return software.amazon.jsii.tests.calculator.lib.IDoublable.class;
-            case "@scope/jsii-calc-lib.IFriendly": return software.amazon.jsii.tests.calculator.lib.IFriendly.class;
-            case "@scope/jsii-calc-lib.IThreeLevelsInterface": return software.amazon.jsii.tests.calculator.lib.IThreeLevelsInterface.class;
-            case "@scope/jsii-calc-lib.MyFirstStruct": return software.amazon.jsii.tests.calculator.lib.MyFirstStruct.class;
-            case "@scope/jsii-calc-lib.Number": return software.amazon.jsii.tests.calculator.lib.Number.class;
-            case "@scope/jsii-calc-lib.Operation": return software.amazon.jsii.tests.calculator.lib.Operation.class;
-            case "@scope/jsii-calc-lib.StructWithOnlyOptionals": return software.amazon.jsii.tests.calculator.lib.StructWithOnlyOptionals.class;
-            case "@scope/jsii-calc-lib.Value": return software.amazon.jsii.tests.calculator.lib.Value.class;
-            default: throw new ClassNotFoundException("Unknown JSII type: " + fqn);
+        if (!MODULE_TYPES.containsKey(fqn)) {
+            throw new ClassNotFoundException("Unknown JSII type: " + fqn);
+        }
+        return this.cache.computeIfAbsent(MODULE_TYPES.get(fqn), this::findClass);
+    }
+
+    private Class<?> findClass(final String binaryName) {
+        try {
+            return Class.forName(binaryName);
+        }
+        catch (final ClassNotFoundException exception) {
+            throw new RuntimeException(exception);
         }
     }
 }
diff --git a/...ii-calc-lib/java/src/main/resources/software/amazon/jsii/tests/calculator/lib/$Module.txt b/...ii-calc-lib/java/src/main/resources/software/amazon/jsii/tests/calculator/lib/$Module.txt
@@ -0,0 +1,9 @@
+@scope/jsii-calc-lib.EnumFromScopedModule=software.amazon.jsii.tests.calculator.lib.EnumFromScopedModule
+@scope/jsii-calc-lib.IDoublable=software.amazon.jsii.tests.calculator.lib.IDoublable
+@scope/jsii-calc-lib.IFriendly=software.amazon.jsii.tests.calculator.lib.IFriendly
+@scope/jsii-calc-lib.IThreeLevelsInterface=software.amazon.jsii.tests.calculator.lib.IThreeLevelsInterface
+@scope/jsii-calc-lib.MyFirstStruct=software.amazon.jsii.tests.calculator.lib.MyFirstStruct
+@scope/jsii-calc-lib.Number=software.amazon.jsii.tests.calculator.lib.Number
+@scope/jsii-calc-lib.Operation=software.amazon.jsii.tests.calculator.lib.Operation
+@scope/jsii-calc-lib.StructWithOnlyOptionals=software.amazon.jsii.tests.calculator.lib.StructWithOnlyOptionals
+@scope/jsii-calc-lib.Value=software.amazon.jsii.tests.calculator.lib.Value