Display source info for mixin injected methods (#249)

Co-authored-by: Luck <git@lucko.me>

11 files changed, 806 insertions, 33 deletions

diff --git a/spark-common/src/main/java/me/lucko/spark/common/sampler/AbstractSampler.java b/spark-common/src/main/java/me/lucko/spark/common/sampler/AbstractSampler.java
index 1c217db..3cfef0b 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/sampler/AbstractSampler.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/sampler/AbstractSampler.java
@@ -164,8 +164,16 @@ public abstract class AbstractSampler implements Sampler {
             classSourceVisitor.visit(entry);
         }
 
-        if (classSourceVisitor.hasMappings()) {
-            proto.putAllClassSources(classSourceVisitor.getMapping());
+        if (classSourceVisitor.hasClassSourceMappings()) {
+            proto.putAllClassSources(classSourceVisitor.getClassSourceMapping());
+        }
+
+        if (classSourceVisitor.hasMethodSourceMappings()) {
+            proto.putAllMethodSources(classSourceVisitor.getMethodSourceMapping());
+        }
+
+        if (classSourceVisitor.hasLineSourceMappings()) {
+            proto.putAllLineSources(classSourceVisitor.getLineSourceMapping());
         }
     }
 }
diff --git a/spark-common/src/main/java/me/lucko/spark/common/util/ClassSourceLookup.java b/spark-common/src/main/java/me/lucko/spark/common/util/ClassSourceLookup.java
index bd9ec37..668f31a 100644
--- a/spark-common/src/main/java/me/lucko/spark/common/util/ClassSourceLookup.java
+++ b/spark-common/src/main/java/me/lucko/spark/common/util/ClassSourceLookup.java
@@ -38,9 +38,11 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 /**
- * A function which defines the source of given {@link Class}es.
+ * A function which defines the source of given {@link Class}es or (Mixin) method calls.
  */
 public interface ClassSourceLookup {
 
@@ -53,6 +55,26 @@ public interface ClassSourceLookup {
     @Nullable String identify(Class<?> clazz) throws Exception;
 
     /**
+     * Identify the given method call.
+     *
+     * @param methodCall the method call info
+     * @return the source of the method call
+     */
+    default @Nullable String identify(MethodCall methodCall) throws Exception {
+        return null;
+    }
+
+    /**
+     * Identify the given method call.
+     *
+     * @param methodCall the method call info
+     * @return the source of the method call
+     */
+    default @Nullable String identify(MethodCallByLine methodCall) throws Exception {
+        return null;
+    }
+
+    /**
      * A no-operation {@link ClassSourceLookup}.
      */
     ClassSourceLookup NO_OP = new ClassSourceLookup() {
@@ -156,9 +178,17 @@ public interface ClassSourceLookup {
     interface Visitor {
         void visit(ThreadNode node);
 
-        boolean hasMappings();
+        boolean hasClassSourceMappings();
+
+        Map<String, String> getClassSourceMapping();
+
+        boolean hasMethodSourceMappings();
+
+        Map<String, String> getMethodSourceMapping();
+
+        boolean hasLineSourceMappings();
 
-        Map<String, String> getMapping();
+        Map<String, String> getLineSourceMapping();
     }
 
     static Visitor createVisitor(ClassSourceLookup lookup) {
@@ -177,25 +207,46 @@ public interface ClassSourceLookup {
         }
 
         @Override
-        public boolean hasMappings() {
+        public boolean hasClassSourceMappings() {
+            return false;
+        }
+
+        @Override
+        public Map<String, String> getClassSourceMapping() {
+            return Collections.emptyMap();
+        }
+
+        @Override
+        public boolean hasMethodSourceMappings() {
+            return false;
+        }
+
+        @Override
+        public Map<String, String> getMethodSourceMapping() {
+            return Collections.emptyMap();
+        }
+
+        @Override
+        public boolean hasLineSourceMappings() {
             return false;
         }
 
         @Override
-        public Map<String, String> getMapping() {
+        public Map<String, String> getLineSourceMapping() {
             return Collections.emptyMap();
         }
     }
 
     /**
-     * Visitor which scans {@link StackTraceNode}s and accumulates class identities.
+     * Visitor which scans {@link StackTraceNode}s and accumulates class/method call identities.
      */
     class VisitorImpl implements Visitor {
         private final ClassSourceLookup lookup;
         private final ClassFinder classFinder = new ClassFinder();
 
-        // class name --> identifier (plugin name)
-        private final Map<String, String> map = new HashMap<>();
+        private final SourcesMap<String> classSources = new SourcesMap<>(Function.identity());
+        private final SourcesMap<MethodCall> methodSources = new SourcesMap<>(MethodCall::toString);
+        private final SourcesMap<MethodCallByLine> lineSources = new SourcesMap<>(MethodCallByLine::toString);
 
         VisitorImpl(ClassSourceLookup lookup) {
             this.lookup = lookup;
@@ -208,34 +259,194 @@ public interface ClassSourceLookup {
             }
         }
 
+        private void visitStackNode(StackTraceNode node) {
+            this.classSources.computeIfAbsent(
+                    node.getClassName(),
+                    className -> {
+                        Class<?> clazz = this.classFinder.findClass(className);
+                        if (clazz == null) {
+                            return null;
+                        }
+                        return this.lookup.identify(clazz);
+                    });
+
+            if (node.getMethodDescription() != null) {
+                MethodCall methodCall = new MethodCall(node.getClassName(), node.getMethodName(), node.getMethodDescription());
+                this.methodSources.computeIfAbsent(methodCall, this.lookup::identify);
+            } else {
+                MethodCallByLine methodCall = new MethodCallByLine(node.getClassName(), node.getMethodName(), node.getLineNumber());
+                this.lineSources.computeIfAbsent(methodCall, this.lookup::identify);
+            }
+
+            // recursively
+            for (StackTraceNode child : node.getChildren()) {
+                visitStackNode(child);
+            }
+        }
+
         @Override
-        public boolean hasMappings() {
-            return !this.map.isEmpty();
+        public boolean hasClassSourceMappings() {
+            return this.classSources.hasMappings();
         }
 
         @Override
-        public Map<String, String> getMapping() {
-            this.map.values().removeIf(Objects::isNull);
-            return this.map;
+        public Map<String, String> getClassSourceMapping() {
+            return this.classSources.export();
         }
 
-        private void visitStackNode(StackTraceNode node) {
-            String className = node.getClassName();
-            if (!this.map.containsKey(className)) {
+        @Override
+        public boolean hasMethodSourceMappings() {
+            return this.methodSources.hasMappings();
+        }
+
+        @Override
+        public Map<String, String> getMethodSourceMapping() {
+            return this.methodSources.export();
+        }
+
+        @Override
+        public boolean hasLineSourceMappings() {
+            return this.lineSources.hasMappings();
+        }
+
+        @Override
+        public Map<String, String> getLineSourceMapping() {
+            return this.lineSources.export();
+        }
+    }
+
+    final class SourcesMap<T> {
+        // <key> --> identifier (plugin name)
+        private final Map<T, String> map = new HashMap<>();
+        private final Function<? super T, String> keyToStringFunction;
+
+        private SourcesMap(Function<? super T, String> keyToStringFunction) {
+            this.keyToStringFunction = keyToStringFunction;
+        }
+
+        public void computeIfAbsent(T key, ComputeSourceFunction<T> function) {
+            if (!this.map.containsKey(key)) {
                 try {
-                    Class<?> clazz = this.classFinder.findClass(className);
-                    Objects.requireNonNull(clazz);
-                    this.map.put(className, this.lookup.identify(clazz));
+                    this.map.put(key, function.compute(key));
                 } catch (Throwable e) {
-                    this.map.put(className, null);
+                    this.map.put(key, null);
                 }
             }
+        }
 
-            // recursively
-            for (StackTraceNode child : node.getChildren()) {
-                visitStackNode(child);
+        public boolean hasMappings() {
+            this.map.values().removeIf(Objects::isNull);
+            return !this.map.isEmpty();
+        }
+
+        public Map<String, String> export() {
+            this.map.values().removeIf(Objects::isNull);
+            if (this.keyToStringFunction.equals(Function.identity())) {
+                //noinspection unchecked
+                return (Map<String, String>) this.map;
+            } else {
+                return this.map.entrySet().stream().collect(Collectors.toMap(
+                        e -> this.keyToStringFunction.apply(e.getKey()),
+                        Map.Entry::getValue
+                ));
             }
         }
+
+        private interface ComputeSourceFunction<T> {
+            String compute(T key) throws Exception;
+        }
+    }
+
+    /**
+     * Encapsulates information about a given method call using the name + method description.
+     */
+    final class MethodCall {
+        private final String className;
+        private final String methodName;
+        private final String methodDescriptor;
+
+        public MethodCall(String className, String methodName, String methodDescriptor) {
+            this.className = className;
+            this.methodName = methodName;
+            this.methodDescriptor = methodDescriptor;
+        }
+
+        public String getClassName() {
+            return this.className;
+        }
+
+        public String getMethodName() {
+            return this.methodName;
+        }
+
+        public String getMethodDescriptor() {
+            return this.methodDescriptor;
+        }
+
+        @Override
+        public String toString() {
+            return this.className + ";" + this.methodName + ";" + this.methodDescriptor;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (!(o instanceof MethodCall)) return false;
+            MethodCall that = (MethodCall) o;
+            return this.className.equals(that.className) &&
+                    this.methodName.equals(that.methodName) &&
+                    this.methodDescriptor.equals(that.methodDescriptor);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(this.className, this.methodName, this.methodDescriptor);
+        }
+    }
+
+    /**
+     * Encapsulates information about a given method call using the name + line number.
+     */
+    final class MethodCallByLine {
+        private final String className;
+        private final String methodName;
+        private final int lineNumber;
+
+        public MethodCallByLine(String className, String methodName, int lineNumber) {
+            this.className = className;
+            this.methodName = methodName;
+            this.lineNumber = lineNumber;
+        }
+
+        public String getClassName() {
+            return this.className;
+        }
+
+        public String getMethodName() {
+            return this.methodName;
+        }
+
+        public int getLineNumber() {
+            return this.lineNumber;
+        }
+
+        @Override
+        public String toString() {
+            return this.className + ";" + this.lineNumber;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (!(o instanceof MethodCallByLine)) return false;
+            MethodCallByLine that = (MethodCallByLine) o;
+            return this.lineNumber == that.lineNumber && this.className.equals(that.className);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(this.className, this.lineNumber);
+        }
     }
 
 }
diff --git a/spark-common/src/main/proto/spark/spark_sampler.proto b/spark-common/src/main/proto/spark/spark_sampler.proto
index 8d9512a..f670ddf 100644
--- a/spark-common/src/main/proto/spark/spark_sampler.proto
+++ b/spark-common/src/main/proto/spark/spark_sampler.proto
@@ -11,6 +11,8 @@ message SamplerData {
   SamplerMetadata metadata = 1;
   repeated ThreadNode threads = 2;
   map<string, string> class_sources = 3; // optional
+  map<string, string> method_sources = 4; // optional
+  map<string, string> line_sources = 5; // optional
 }
 
 message SamplerMetadata {
diff --git a/spark-fabric/build.gradle b/spark-fabric/build.gradle
index 30b1ff6..fce859a 100644
--- a/spark-fabric/build.gradle
+++ b/spark-fabric/build.gradle
@@ -66,6 +66,10 @@ processResources {
     }
 }
 
+license {
+    exclude '**/smap/SourceMap.java'
+}
+
 shadowJar {
     archiveFileName = "spark-fabric-${project.pluginVersion}-dev.jar"
     configurations = [project.configurations.shade]
@@ -74,12 +78,16 @@ shadowJar {
     relocate 'net.kyori.examination', 'me.lucko.spark.lib.adventure.examination'
     relocate 'net.bytebuddy', 'me.lucko.spark.lib.bytebuddy'
     relocate 'com.google.protobuf', 'me.lucko.spark.lib.protobuf'
-    relocate 'org.objectweb.asm', 'me.lucko.spark.lib.asm'
+//    relocate 'org.objectweb.asm', 'me.lucko.spark.lib.asm'
     relocate 'one.profiler', 'me.lucko.spark.lib.asyncprofiler'
 
     exclude 'module-info.class'
     exclude 'META-INF/maven/**'
     exclude 'META-INF/proguard/**'
+
+    dependencies {
+        exclude(dependency('org.ow2.asm::'))
+    }
 }
 
 task remappedShadowJar(type: RemapJarTask) {
diff --git a/spark-fabric/src/main/java/me/lucko/spark/fabric/FabricClassSourceLookup.java b/spark-fabric/src/main/java/me/lucko/spark/fabric/FabricClassSourceLookup.java
index 7030680..9ffac18 100644
--- a/spark-fabric/src/main/java/me/lucko/spark/fabric/FabricClassSourceLookup.java
+++ b/spark-fabric/src/main/java/me/lucko/spark/fabric/FabricClassSourceLookup.java
@@ -22,18 +22,35 @@ package me.lucko.spark.fabric;
 
 import com.google.common.collect.ImmutableMap;
 
+import me.lucko.spark.common.util.ClassFinder;
 import me.lucko.spark.common.util.ClassSourceLookup;
+import me.lucko.spark.fabric.smap.MixinUtils;
+import me.lucko.spark.fabric.smap.SourceMap;
+import me.lucko.spark.fabric.smap.SourceMapProvider;
 
 import net.fabricmc.loader.api.FabricLoader;
 import net.fabricmc.loader.api.ModContainer;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.objectweb.asm.Type;
+import org.spongepowered.asm.mixin.FabricUtil;
+import org.spongepowered.asm.mixin.extensibility.IMixinConfig;
+import org.spongepowered.asm.mixin.transformer.Config;
+import org.spongepowered.asm.mixin.transformer.meta.MixinMerged;
+
+import java.lang.reflect.Method;
+import java.net.URI;
 import java.nio.file.Path;
 import java.util.Collection;
 import java.util.Map;
 
 public class FabricClassSourceLookup extends ClassSourceLookup.ByCodeSource {
+
+    private final ClassFinder classFinder = new ClassFinder();
+    private final SourceMapProvider smapProvider = new SourceMapProvider();
+
     private final Path modsDirectory;
-    private final Map<Path, String> pathToModMap;
+    private final Map<String, String> pathToModMap;
 
     public FabricClassSourceLookup() {
         FabricLoader loader = FabricLoader.getInstance();
@@ -43,7 +60,7 @@ public class FabricClassSourceLookup extends ClassSourceLookup.ByCodeSource {
 
     @Override
     public String identifyFile(Path path) {
-        String id = this.pathToModMap.get(path);
+        String id = this.pathToModMap.get(path.toAbsolutePath().normalize().toString());
         if (id != null) {
             return id;
         }
@@ -55,11 +72,141 @@ public class FabricClassSourceLookup extends ClassSourceLookup.ByCodeSource {
         return super.identifyFileName(this.modsDirectory.relativize(path).toString());
     }
 
-    private static Map<Path, String> constructPathToModIdMap(Collection<ModContainer> mods) {
-        ImmutableMap.Builder<Path, String> builder = ImmutableMap.builder();
+    @Override
+    public @Nullable String identify(MethodCall methodCall) throws Exception {
+        String className = methodCall.getClassName();
+        String methodName = methodCall.getMethodName();
+        String methodDesc = methodCall.getMethodDescriptor();
+
+        if (className.equals("native") || methodName.equals("<init>") || methodName.equals("<clinit>")) {
+            return null;
+        }
+
+        Class<?> clazz = this.classFinder.findClass(className);
+        if (clazz == null) {
+            return null;
+        }
+
+        Class<?>[] params = getParameterTypesForMethodDesc(methodDesc);
+        Method reflectMethod = clazz.getDeclaredMethod(methodName, params);
+
+        MixinMerged mixinMarker = reflectMethod.getDeclaredAnnotation(MixinMerged.class);
+        if (mixinMarker == null) {
+            return null;
+        }
+
+        return modIdFromMixinClass(mixinMarker.mixin());
+    }
+
+    @Override
+    public @Nullable String identify(MethodCallByLine methodCall) throws Exception {
+        String className = methodCall.getClassName();
+        String methodName = methodCall.getMethodName();
+        int lineNumber = methodCall.getLineNumber();
+
+        if (className.equals("native") || methodName.equals("<init>") || methodName.equals("<clinit>")) {
+            return null;
+        }
+
+        SourceMap smap = this.smapProvider.getSourceMap(className);
+        if (smap == null) {
+            return null;
+        }
+
+        int[] inputLineInfo = smap.getReverseLineMapping().get(lineNumber);
+        if (inputLineInfo == null || inputLineInfo.length == 0) {
+            return null;
+        }
+
+        for (int fileInfoIds : inputLineInfo) {
+            SourceMap.FileInfo inputFileInfo = smap.getFileInfo().get(fileInfoIds);
+            if (inputFileInfo == null) {
+                continue;
+            }
+
+            String path = inputFileInfo.path();
+            if (path.endsWith(".java")) {
+                path = path.substring(0, path.length() - 5);
+            }
+
+            String possibleMixinClassName = path.replace('/', '.');
+            if (possibleMixinClassName.equals(className)) {
+                continue;
+            }
+
+            return modIdFromMixinClass(possibleMixinClassName);
+        }
+
+        return null;
+    }
+
+    private static String modIdFromMixinClass(String mixinClassName) {
+        for (Config config : MixinUtils.getMixinConfigs().values()) {
+            IMixinConfig mixinConfig = config.getConfig();
+            if (mixinClassName.startsWith(mixinConfig.getMixinPackage())) {
+                return mixinConfig.getDecoration(FabricUtil.KEY_MOD_ID);
+            }
+        }
+        return null;
+    }
+
+    private Class<?>[] getParameterTypesForMethodDesc(String methodDesc) {
+        Type methodType = Type.getMethodType(methodDesc);
+        Class<?>[] params = new Class[methodType.getArgumentTypes().length];
+        Type[] argumentTypes = methodType.getArgumentTypes();
+
+        for (int i = 0, argumentTypesLength = argumentTypes.length; i < argumentTypesLength; i++) {
+            Type argumentType = argumentTypes[i];
+            params[i] = getClassFromType(argumentType);
+        }
+
+        return params;
+    }
+
+    private Class<?> getClassFromType(Type type) {
+        return switch (type.getSort()) {
+            case Type.VOID -> void.class;
+            case Type.BOOLEAN -> boolean.class;
+            case Type.CHAR -> char.class;
+            case Type.BYTE -> byte.class;
+            case Type.SHORT -> short.class;
+            case Type.INT -> int.class;
+            case Type.FLOAT -> float.class;
+            case Type.LONG -> long.class;
+            case Type.DOUBLE -> double.class;
+            case Type.ARRAY -> {
+                final Class<?> classFromType = getClassFromType(type.getElementType());
+                Class<?> result = classFromType;
+                if (classFromType != null) {
+                    for (int i = 0; i < type.getDimensions(); i++) {
+                        result = result.arrayType();
+                    }
+                }
+                yield result;
+            }
+            case Type.OBJECT -> this.classFinder.findClass(type.getClassName());
+            default -> null;
+        };
+    }
+
+    private static Map<String, String> constructPathToModIdMap(Collection<ModContainer> mods) {
+        ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
         for (ModContainer mod : mods) {
-            Path path = mod.getRootPath().toAbsolutePath().normalize();
-            builder.put(path, mod.getMetadata().getId());
+            String modId = mod.getMetadata().getId();
+            if (modId.equals("java")) {
+                continue;
+            }
+
+            for (Path path : mod.getRootPaths()) {
+                URI uri = path.toUri();
+                if (uri.getScheme().equals("jar") && path.toString().equals("/")) { // ZipFileSystem
+                    String zipFilePath = path.getFileSystem().toString();
+                    builder.put(zipFilePath, modId);
+                } else {
+                    builder.put(path.toAbsolutePath().normalize().toString(), modId);
+                }
+
+            }
         }
         return builder.build();
     }
diff --git a/spark-fabric/src/main/java/me/lucko/spark/fabric/plugin/FabricSparkMixinPlugin.java b/spark-fabric/src/main/java/me/lucko/spark/fabric/plugin/FabricSparkMixinPlugin.java
new file mode 100644
index 0000000..cfc8c95
--- /dev/null
+++ b/spark-fabric/src/main/java/me/lucko/spark/fabric/plugin/FabricSparkMixinPlugin.java
@@ -0,0 +1,71 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.fabric.plugin;
+
+import me.lucko.spark.fabric.smap.SourceDebugCache;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.objectweb.asm.tree.ClassNode;
+import org.spongepowered.asm.mixin.MixinEnvironment;
+import org.spongepowered.asm.mixin.extensibility.IMixinConfigPlugin;
+import org.spongepowered.asm.mixin.extensibility.IMixinInfo;
+import org.spongepowered.asm.mixin.transformer.IMixinTransformer;
+import org.spongepowered.asm.mixin.transformer.ext.Extensions;
+import org.spongepowered.asm.mixin.transformer.ext.IExtension;
+import org.spongepowered.asm.mixin.transformer.ext.ITargetClassContext;
+
+import java.util.List;
+import java.util.Set;
+
+public class FabricSparkMixinPlugin implements IMixinConfigPlugin, IExtension {
+
+    private static final Logger LOGGER = LogManager.getLogger("spark");
+
+    @Override
+    public void onLoad(String mixinPackage) {
+        Object activeTransformer = MixinEnvironment.getCurrentEnvironment().getActiveTransformer();
+        if (activeTransformer instanceof IMixinTransformer transformer && transformer.getExtensions() instanceof Extensions extensions) {
+            extensions.add(this);
+        } else {
+            LOGGER.error(
+                    "Failed to initialize SMAP parser for spark profiler. " +
+                    "Mod information for mixin injected methods is now only available with the async-profiler engine."
+            );
+        }
+    }
+
+    @Override
+    public void export(MixinEnvironment env, String name, boolean force, ClassNode classNode) {
+        SourceDebugCache.put(name, classNode);
+    }
+
+    // noop
+    @Override public String getRefMapperConfig() { return null; }
+    @Override public boolean shouldApplyMixin(String targetClassName, String mixinClassName) { return true; }
+    @Override public void acceptTargets(Set<String> myTargets, Set<String> otherTargets) { }
+    @Override public List<String> getMixins() { return null; }
+    @Override public void preApply(String targetClassName, ClassNode targetClass, String mixinClassName, IMixinInfo mixinInfo) { }
+    @Override public void postApply(String targetClassName, ClassNode targetClass, String mixinClassName, IMixinInfo mixinInfo) { }
+    @Override public boolean checkActive(MixinEnvironment environment) { return true; }
+    @Override public void preApply(ITargetClassContext context) { }
+    @Override public void postApply(ITargetClassContext context) { }
+
+}
diff --git a/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/MixinUtils.java b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/MixinUtils.java
new file mode 100644
index 0000000..ebf2766
--- /dev/null
+++ b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/MixinUtils.java
@@ -0,0 +1,52 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.fabric.smap;
+
+import org.spongepowered.asm.mixin.transformer.Config;
+
+import java.lang.reflect.Field;
+import java.util.HashMap;
+import java.util.Map;
+
+public enum MixinUtils {
+    ;
+
+    private static final Map<String, Config> MIXIN_CONFIGS;
+
+    static {
+        Map<String, Config> configs;
+        try {
+            Field allConfigsField = Config.class.getDeclaredField("allConfigs");
+            allConfigsField.setAccessible(true);
+
+            //noinspection unchecked
+            configs = (Map<String, Config>) allConfigsField.get(null);
+        } catch (Exception e) {
+            e.printStackTrace();
+            configs = new HashMap<>();
+        }
+        MIXIN_CONFIGS = configs;
+    }
+
+    public static Map<String, Config> getMixinConfigs() {
+        return MIXIN_CONFIGS;
+    }
+}
diff --git a/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceDebugCache.java b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceDebugCache.java
new file mode 100644
index 0000000..88adae6
--- /dev/null
+++ b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceDebugCache.java
@@ -0,0 +1,87 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.fabric.smap;
+
+import org.objectweb.asm.tree.ClassNode;
+import org.spongepowered.asm.service.IClassBytecodeProvider;
+import org.spongepowered.asm.service.MixinService;
+
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Caches the lookup of class -> source debug info for classes loaded on the JVM.
+ *
+ * The {@link me.lucko.spark.fabric.plugin.FabricSparkMixinPlugin} also supplements this cache with
+ * extra information as classes are exported.
+ */
+public enum SourceDebugCache {
+    ;
+
+    // class name -> smap
+    private static final Map<String, SmapValue> CACHE = new ConcurrentHashMap<>();
+
+    public static void put(String className, ClassNode node) {
+        if (className == null || node == null) {
+            return;
+        }
+        className = className.replace('/', '.');
+        CACHE.put(className, SmapValue.of(node.sourceDebug));
+    }
+
+    public static String getSourceDebugInfo(String className) {
+        SmapValue cached = CACHE.get(className);
+        if (cached != null) {
+            return cached.value();
+        }
+
+        try {
+            IClassBytecodeProvider provider = MixinService.getService().getBytecodeProvider();
+            ClassNode classNode = provider.getClassNode(className.replace('.', '/'));
+
+            if (classNode != null) {
+                put(className, classNode);
+                return classNode.sourceDebug;
+            }
+
+        } catch (Exception e) {
+            // ignore
+        }
+
+        CACHE.put(className, SmapValue.NULL);
+        return null;
+    }
+
+    private record SmapValue(String value) {
+        static final SmapValue NULL = new SmapValue(null);
+
+        static SmapValue of(String value) {
+            if (value == null) {
+                return NULL;
+            } else {
+                return new SmapValue(value);
+            }
+        }
+
+    }
+
+}
diff --git a/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceMap.java b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceMap.java
new file mode 100644
index 0000000..5105a26
--- /dev/null
+++ b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceMap.java
@@ -0,0 +1,133 @@
+/*
+ * SMAPSourceDebugExtension.java - Parse source debug extensions and
+ * enhance stack traces.
+ *
+ * Copyright (c) 2012 Michael Schierl
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * - Neither name of the copyright holders nor the names of its
+ *   contributors may be used to endorse or promote products derived from
+ *   this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND THE CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+ * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package me.lucko.spark.fabric.smap;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Utility class to parse "SMAP" (source map) information from loaded Java classes.
+ *
+ * @author <a href="https://stackoverflow.com/a/11299757">Michael Schierl</a>
+ */
+public class SourceMap {
+
+    private final String generatedFileName;
+    private final String firstStratum;
+    private final Map<Integer, FileInfo> fileinfo = new HashMap<>();
+    private final Map<Integer, int[]> reverseLineMapping = new HashMap<>();
+
+    private static final Pattern LINE_INFO_PATTERN = Pattern.compile("([0-9]+)(?:#([0-9]+))?(?:,([0-9]+))?:([0-9]+)(?:,([0-9]+))?");
+
+    public SourceMap(String value) {
+        String[] lines = value.split("\n");
+        if (!lines[0].equals("SMAP") || !lines[3].startsWith("*S ") || !lines[4].equals("*F")) {
+            throw new IllegalArgumentException(value);
+        }
+
+        this.generatedFileName = lines[1];
+        this.firstStratum = lines[3].substring(3);
+
+        int idx = 5;
+        while (!lines[idx].startsWith("*")) {
+            String infoline = lines[idx++];
+            String path = null;
+
+            if (infoline.startsWith("+ ")) {
+                path = lines[idx++];
+                infoline = infoline.substring(2);
+            }
+
+            int pos = infoline.indexOf(" ");
+            int filenum = Integer.parseInt(infoline.substring(0, pos));
+            String name = infoline.substring(pos + 1);
+
+            this.fileinfo.put(filenum, new FileInfo(name, path == null ? name : path));
+        }
+
+        if (lines[idx].equals("*L")) {
+            idx++;
+            int lastLFI = 0;
+
+            while (!lines[idx].startsWith("*")) {
+                Matcher m = LINE_INFO_PATTERN.matcher(lines[idx++]);
+                if (!m.matches()) {
+                    throw new IllegalArgumentException(lines[idx - 1]);
+                }
+
+                int inputStartLine = Integer.parseInt(m.group(1));
+                int lineFileID = m.group(2) == null ? lastLFI : Integer.parseInt(m.group(2));
+                int repeatCount = m.group(3) == null ? 1 : Integer.parseInt(m.group(3));
+                int outputStartLine = Integer.parseInt(m.group(4));
+                int outputLineIncrement = m.group(5) == null ? 1 : Integer.parseInt(m.group(5));
+
+                for (int i = 0; i < repeatCount; i++) {
+                    int[] inputMapping = new int[] { lineFileID, inputStartLine + i };
+                    int baseOL = outputStartLine + i * outputLineIncrement;
+
+                    for (int ol = baseOL; ol < baseOL + outputLineIncrement; ol++) {
+                        if (!this.reverseLineMapping.containsKey(ol)) {
+                            this.reverseLineMapping.put(ol, inputMapping);
+                        }
+                    }
+                }
+
+                lastLFI = lineFileID;
+            }
+        }
+    }
+
+    public String getGeneratedFileName() {
+        return this.generatedFileName;
+    }
+
+    public String getFirstStratum() {
+        return this.firstStratum;
+    }
+
+    public Map<Integer, FileInfo> getFileInfo() {
+        return this.fileinfo;
+    }
+
+    public Map<Integer, int[]> getReverseLineMapping() {
+        return this.reverseLineMapping;
+    }
+
+    public record FileInfo(String name, String path) { }
+}
\ No newline at end of file
diff --git a/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceMapProvider.java b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceMapProvider.java
new file mode 100644
index 0000000..1a4f246
--- /dev/null
+++ b/spark-fabric/src/main/java/me/lucko/spark/fabric/smap/SourceMapProvider.java
@@ -0,0 +1,53 @@
+/*
+ * This file is part of spark.
+ *
+ *  Copyright (c) lucko (Luck) <luck@lucko.me>
+ *  Copyright (c) contributors
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package me.lucko.spark.fabric.smap;
+
+import org.jetbrains.annotations.Nullable;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class SourceMapProvider {
+    private final Map<String, SourceMap> cache = new HashMap<>();
+
+    public @Nullable SourceMap getSourceMap(String className) {
+        if (this.cache.containsKey(className)) {
+            return this.cache.get(className);
+        }
+
+        SourceMap smap = null;
+        try {
+            String value = SourceDebugCache.getSourceDebugInfo(className);
+            if (value != null) {
+                value = value.replaceAll("\r\n?", "\n");
+                if (value.startsWith("SMAP\n")) {
+                    smap = new SourceMap(value);
+                }
+            }
+        } catch (Exception e) {
+            // ignore
+        }
+
+        this.cache.put(className, smap);
+        return smap;
+    }
+
+}
diff --git a/spark-fabric/src/main/resources/spark.mixins.json b/spark-fabric/src/main/resources/spark.mixins.json
index e75b34f..63c1078 100644
--- a/spark-fabric/src/main/resources/spark.mixins.json
+++ b/spark-fabric/src/main/resources/spark.mixins.json
@@ -11,5 +11,6 @@
   "server": [
     "ServerEntityManagerAccessor",
     "ServerWorldAccessor"
-  ]
+  ],
+  "plugin": "me.lucko.spark.fabric.plugin.FabricSparkMixinPlugin"
 }
\ No newline at end of file