Move DSL class loading under core/dsl, de-duplicate class definition, and name the classify branches

docs/en/changes/changes.md

@@ -2,6 +2,7 @@
 
 #### Project
 
+* Move the DSL class-loading machinery under `core/dsl`. `core/classloader` held only DSL types — `RuleClassLoader`, `DSLClassLoaderManager`, `ClassLoaderGc`, `UnloadProbePayload` and `BytecodeClassDefiner` — so it is now `core/dsl/classloader`, and `Catalog` moves to `core/dsl` because a rule-file taxonomy is not a class-loading concern. Three copies of the "define a generated class into the right loader" dispatch (MAL, LAL, `MeterSystem`) collapse into a static `BytecodeClassDefiner.define`, which also gives the JDK 17 `--add-opens` rationale one home instead of four. Three of the four copies of the generated-class dump-directory lookup become `DslGeneratedFileWriter.resolveClassDumpDir`; OAL keeps its own, because its debug flag is settable independently of the environment variable and two tests rely on that. No behaviour change.
 * Extend the `GET /inspect/entities` admin API to inspect a metric persisted by **any** OAP, even one this node does not define locally. When the metric is unknown to the local registry, the caller supplies `valueColumn` + `valueType` and the storage backend resolves the physical index/table/group from its own running config (no DB schema/table-metadata read): ES uses the merged `metrics-all` index + `metric_table` discriminator, JDBC probes the node's function tables by the `table_name` discriminator, and BanyanDB synthesizes a read-only measure schema. Scope is no longer required — the `entity_id` is decoded structurally (service / 2nd-level / relations) with a generic `name` leaf. Locally-defined metrics keep the exact field names, scope, and `mqeEntity` as before.
 * Add the `POST /inspect/values` admin API — read the value series of a metric persisted by **another** OAP (one this node does not define locally) by supplying its `{valueColumn, valueType}`. The real MQE engine runs over a request-scoped `InspectQueryContext` overlay (provide-if-absent — the local catalog always wins) that makes the foreign metric look registered to every read path: `ValueColumnMetadata` resolves its value column / type / scope, and the storage location registries resolve where it lives (`MetadataRegistry` synthesizes a BanyanDB measure schema, `IndexController` resolves the ES `metrics-all` index, `TableHelper` probes the JDBC function tables), so the read returns the native MQE `ExpressionResult` with no per-DAO special-casing. Admin-only (a forced read this OAP cannot validate); not mirrored onto the public REST / GraphQL surface. See the [Inspect API](../setup/backend/admin-api/inspect.md).
 * Remove the always-on alarm-to-event conversion (`EventHookCallback`). A triggered alarm is no longer synthesized into the events pipeline as an `Alarm`/`AlarmRecovery` event; events now originate only from real event sources (agents, SkyWalking CLI, Kubernetes Event Exporter). Alarms remain available through the alarm store (`getAlarm`/`queryAlarms`) and the configured alarm hooks. This drops a documented "Known Event" and removes 1-2 synthetic event records per alarm fire.
@@ -256,7 +257,7 @@
 
 #### OAP Server
 * Fix LAL's `segmentId` and `spanId` extractor statements, which the grammar accepted and the parser never implemented. `LALParser.g4` declares `traceIdStatement`, `segmentIdStatement` and `spanIdStatement`, and the codegen already carried `setSegmentId`/`setSpanId` in its setter table, but `LALScriptParser.visitExtractorStatement` had a branch for only the first of the three. The remaining alternatives fell through to a line that assumed whatever was left had to be an `ifStatement`, so a rule writing `segmentId ...` failed at boot with a `NullPointerException` naming `IfStatementContext` — for a rule line containing no `if`. Both statements now work, and an unhandled extractor statement reports its own rule line instead of throwing. Existing log records are unaffected: `LogBuilder` copies trace id, segment id and span id straight from the log's metadata, and only skips that copy when a rule has set them — which no shipped rule did, which is why the gap went unnoticed. Dedicated execution tests now cover reading all three fields from `log.traceContext.*` and writing all three from an extractor.
-* Remove dead code from the DSL subsystem and correct the shared kernel's own documentation. Deleted `DslContentHash` (a byte-identical, zero-caller twin of the live `ContentHash`), the unused `oal-rt` metrics-function registry, `LogAnalyzerFactory`, `LALCodegenHelper.METADATA_GETTER_ALIASES` (a permanently empty map whose reader branch could never execute — the DSL-name-to-getter mismatch it existed for no longer exists, since `LogMetadata.TraceContext` names the field `traceSegmentId` directly), and three unreferenced members. Three kernel classes carried javadoc asserting consumers that do not exist — `DSLClassLoaderManager` claimed the MAL and LAL compile paths reach for its singleton, `LogDataDebugDump` claimed core renders through it, and `DslContentHash` instructed the reader to consolidate toward the dead copy; a false rationale in a shared kernel is an instruction to the next contributor, so those are now what the call sites actually support. `OALDebug`, `OALDebugRecorder` and `DebugHolderProvider` now record why they sit in core while MAL's and LAL's equivalents do not: `dsl-debugging` declares no `oal-rt` dependency, so they cannot move. `dsl-debugging` also now declares its `server-core` dependency directly instead of inheriting it transitively.
+* Remove dead code from the DSL subsystem and correct the shared kernel's own documentation. Deleted `DslContentHash` (a byte-identical, zero-caller twin of the live `ContentHash`), the unused `oal-rt` metrics-function registry, `LogAnalyzerFactory`, `LALCodegenHelper.METADATA_GETTER_ALIASES` (a permanently empty map whose reader branch could never execute — the DSL-name-to-getter mismatch it existed for no longer exists, since `LogMetadata.TraceContext` names the field `traceSegmentId` directly), and three unreferenced members. Three kernel classes carried javadoc asserting consumers that do not exist — `DSLClassLoaderManager` claimed the MAL and LAL compile paths reach for its singleton, `LogDataDebugDump` claimed core renders through it, and `DslContentHash` instructed the reader to consolidate toward the dead copy; a false rationale in a shared kernel is an instruction to the next contributor, so those are now what the call sites actually support. `OALDebug`, `OALDebugRecorder` and `DebugHolderProvider` now record why they sit in core while MAL's and LAL's equivalents do not: `dsl-debugging` declares no `oal-rt` dependency, so they cannot move.
 * Unify source attribution for every generated DSL class, so a stack frame from OAL, MAL, LAL or Hierarchy code leads back to the rule that produced it.
   - `SourceFile` now names the RULE and its line, then the generated class file: `(otel-rules/activemq/activemq-broker.yaml:32)otel_rules_activemq_activemq_broker_L32_service_meter.java`. The `.java` generated source file is written only under `SW_DYNAMIC_CLASS_ENGINE_DEBUG`, so in a default deployment naming it named nothing; the class name cannot substitute because sanitising maps `/`, `-` and `.` all to `_` and drops the extension.
   - The `_L<n>_` segment was the rules-list index rather than a line, so every file's first rule reported as `L0`. It now carries the rule's real line, resolved by the loaders themselves — including Zabbix and Hierarchy, which supplied no coordinate at all, and the runtime-rule hot-update paths for MAL and LAL, which disagreed with their own boot loaders.

oap-server/analyzer/hierarchy/src/main/java/org/apache/skywalking/oap/server/core/config/v2/compiler/HierarchyRuleClassGenerator.java

@@ -30,9 +30,7 @@
 import javassist.CtNewConstructor;
 import javassist.CtNewMethod;
 import lombok.extern.slf4j.Slf4j;
-import org.apache.skywalking.oap.server.core.WorkPath;
 import org.apache.skywalking.oap.server.core.config.v2.compiler.hierarchy.rule.rt.HierarchyRulePackageHolder;
-import org.apache.skywalking.oap.server.library.util.StringUtil;
 import org.apache.skywalking.oap.server.core.query.type.Service;
 import org.apache.skywalking.oap.server.core.dsl.DslJavaSourceText;
 
@@ -79,9 +77,7 @@ public final class HierarchyRuleClassGenerator {
 
     public HierarchyRuleClassGenerator() {
         this(ClassPool.getDefault());
-        if (StringUtil.isNotEmpty(System.getenv("SW_DYNAMIC_CLASS_ENGINE_DEBUG"))) {
-            classOutputDir = new File(WorkPath.getPath().getParentFile(), "hierarchy-rt");
-        }
+        classOutputDir = DslGeneratedFileWriter.resolveClassDumpDir("hierarchy");
     }
 
     public HierarchyRuleClassGenerator(final ClassPool classPool) {

oap-server/analyzer/log-analyzer/src/main/java/org/apache/skywalking/oap/log/analyzer/v2/compiler/LALClassGenerator.java

@@ -19,12 +19,12 @@
 
 import org.apache.skywalking.oap.server.core.dsl.DslGeneratedFileWriter;
 import java.io.File;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
+import javassist.CannotCompileException;
 import javassist.ClassPool;
 import javassist.CtClass;
 import javassist.CtNewConstructor;
@@ -35,12 +35,10 @@
 import org.apache.skywalking.oap.log.analyzer.v2.provider.LALConfigs;
 import org.apache.skywalking.oap.server.core.dsl.DslClassNaming;
 import org.apache.skywalking.oap.server.core.dsl.DslSourceRef;
-import org.apache.skywalking.oap.server.core.classloader.BytecodeClassDefiner;
+import org.apache.skywalking.oap.server.core.dsl.classloader.BytecodeClassDefiner;
 import org.apache.skywalking.oap.server.core.dsl.debug.DSLDebugCodegenSwitch;
 import org.apache.skywalking.oap.server.core.source.LogBuilder;
 import org.apache.skywalking.oap.log.analyzer.v2.dsl.LalExpression;
-import org.apache.skywalking.oap.server.core.WorkPath;
-import org.apache.skywalking.oap.server.library.util.StringUtil;
 import org.apache.skywalking.oap.server.core.dsl.DslJavaSourceText;
 
 /**
@@ -219,9 +217,7 @@ void restoreProtoVarState(final Object[] state) {
 
     public LALClassGenerator() {
         this(ClassPool.getDefault(), null);
-        if (StringUtil.isNotEmpty(System.getenv("SW_DYNAMIC_CLASS_ENGINE_DEBUG"))) {
-            classOutputDir = new File(WorkPath.getPath().getParentFile(), "lal-rt");
-        }
+        classOutputDir = DslGeneratedFileWriter.resolveClassDumpDir("lal");
     }
 
     public LALClassGenerator(final ClassPool classPool) {
@@ -508,26 +504,12 @@ private String buildSourceText(final CtClass ctClass,
      * (startup path: class lands in the OAP app loader alongside
      * {@link LalExpressionPackageHolder}).
      *
-     * <p>{@link BytecodeClassDefiner} loaders (the runtime-rule {@code RuleClassLoader})
-     * receive the {@code CtClass.toBytecode()} bytes via their public {@code defineClass}
-     * — bypasses Javassist's deprecated {@code toClass(loader, ProtectionDomain)} reflection
-     * path so we don't need {@code --add-opens java.base/java.lang} on the OAP container.
-     * Same shape as {@code MALClassGenerator}; both DSLs share the contract.
+     * <p>Which of the two definition paths applies, and why the
+     * {@link BytecodeClassDefiner} one exists at all, is documented on
+     * {@link BytecodeClassDefiner#define}.
      */
-    private Class<?> defineClass(final CtClass ctClass) throws javassist.CannotCompileException {
-        if (targetClassLoader != null) {
-            if (targetClassLoader instanceof BytecodeClassDefiner) {
-                try {
-                    return ((BytecodeClassDefiner) targetClassLoader)
-                        .defineClass(ctClass.getName(), ctClass.toBytecode());
-                } catch (final IOException e) {
-                    throw new javassist.CannotCompileException(
-                        "failed to serialise " + ctClass.getName() + " bytes", e);
-                }
-            }
-            return ctClass.toClass(targetClassLoader, null);
-        }
-        return ctClass.toClass(LalExpressionPackageHolder.class);
+    private Class<?> defineClass(final CtClass ctClass) throws CannotCompileException {
+        return BytecodeClassDefiner.define(ctClass, targetClassLoader, LalExpressionPackageHolder.class);
     }
 
     private static boolean hasParsedAccess(

oap-server/analyzer/meter-analyzer/src/main/java/org/apache/skywalking/oap/meter/analyzer/v2/compiler/MALClassGenerator.java

@@ -20,23 +20,21 @@
 import org.apache.skywalking.oap.server.core.dsl.DslGeneratedFileWriter;
 import org.apache.skywalking.oap.server.core.dsl.DslSourceRef;
 import java.io.File;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import javassist.CannotCompileException;
 import javassist.ClassPool;
 import javassist.CtClass;
 import javassist.CtNewConstructor;
 import javassist.CtNewMethod;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.meter.analyzer.v2.compiler.rt.MalExpressionPackageHolder;
-import org.apache.skywalking.oap.server.core.classloader.BytecodeClassDefiner;
+import org.apache.skywalking.oap.server.core.dsl.classloader.BytecodeClassDefiner;
 import org.apache.skywalking.oap.meter.analyzer.v2.dsl.ExpressionMetadata;
 import org.apache.skywalking.oap.meter.analyzer.v2.dsl.MalExpression;
 import org.apache.skywalking.oap.meter.analyzer.v2.dsl.MalFilter;
-import org.apache.skywalking.oap.server.core.WorkPath;
-import org.apache.skywalking.oap.server.library.util.StringUtil;
 import org.apache.skywalking.oap.server.core.dsl.DslJavaSourceText;
 
 /**
@@ -76,10 +74,7 @@ public final class MALClassGenerator {
 
     public MALClassGenerator() {
         this(createClassPool(), null);
-        if (StringUtil.isNotEmpty(System.getenv("SW_DYNAMIC_CLASS_ENGINE_DEBUG"))) {
-            bytecodeHelper.setClassOutputDir(
-                new File(WorkPath.getPath().getParentFile(), "mal-rt"));
-        }
+        bytecodeHelper.setClassOutputDir(DslGeneratedFileWriter.resolveClassDumpDir("mal"));
     }
 
     private static ClassPool createClassPool() {
@@ -251,29 +246,12 @@ private static String wrapMalFilterSource(final CtClass ctClass, final String fi
      * (startup path: class lands in the OAP app loader alongside
      * {@link MalExpressionPackageHolder}).
      *
-     * <p>When {@code targetClassLoader} implements
-     * {@link org.apache.skywalking.oap.server.core.classloader.BytecodeClassDefiner
-     * BytecodeClassDefiner} (the runtime-rule {@code RuleClassLoader} does), we hand
-     * the loader the {@code CtClass.toBytecode()} bytes and let it invoke its public
-     * {@code defineClass} directly — no Javassist {@code toClass(loader,
-     * ProtectionDomain)} reflection, no {@code --add-opens java.base/java.lang}
-     * requirement on JDK 17+. Otherwise we fall back to the legacy 2-arg toClass for
-     * back-compat, but no shipped loader uses that path today.
+     * <p>Which of the two definition paths applies, and why the
+     * {@link BytecodeClassDefiner} one exists at all, is documented on
+     * {@link BytecodeClassDefiner#define}.
      */
-    private Class<?> defineClass(final CtClass ctClass) throws javassist.CannotCompileException {
-        if (targetClassLoader != null) {
-            if (targetClassLoader instanceof BytecodeClassDefiner) {
-                try {
-                    return ((BytecodeClassDefiner) targetClassLoader)
-                        .defineClass(ctClass.getName(), ctClass.toBytecode());
-                } catch (final IOException e) {
-                    throw new javassist.CannotCompileException(
-                        "failed to serialise " + ctClass.getName() + " bytes", e);
-                }
-            }
-            return ctClass.toClass(targetClassLoader, null);
-        }
-        return ctClass.toClass(MalExpressionPackageHolder.class);
+    private Class<?> defineClass(final CtClass ctClass) throws CannotCompileException {
+        return BytecodeClassDefiner.define(ctClass, targetClassLoader, MalExpressionPackageHolder.class);
     }
 
     /**

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/cluster/DSLDebuggingClusterServiceImpl.java

@@ -42,7 +42,7 @@
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.InstallOutcome;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.Sample;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.SessionLimits;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;
 
 /**

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/lal/LALDebugRecorderFactory.java

@@ -22,7 +22,7 @@
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.DebugRecorderFactory;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.Granularity;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.SessionLimits;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.GateHolder;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;
 

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/lal/LALHolderRegistry.java

@@ -21,7 +21,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.DebugHolderLookup;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.GateHolder;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;
 import org.apache.skywalking.oap.server.library.module.Service;

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/mal/MALDebugRecorderFactory.java

@@ -21,7 +21,7 @@
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.AbstractDebugRecorder;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.DebugRecorderFactory;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.SessionLimits;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.GateHolder;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;
 

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/mal/MALHolderRegistry.java

@@ -21,7 +21,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.DebugHolderLookup;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.GateHolder;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;
 import org.apache.skywalking.oap.server.library.module.Service;

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/module/DSLDebuggingModuleProvider.java

@@ -40,7 +40,7 @@
 import org.apache.skywalking.oap.server.admin.server.cluster.AdminClusterChannelManager;
 import org.apache.skywalking.oap.server.admin.server.module.AdminServerModule;
 import org.apache.skywalking.oap.server.core.analysis.DispatcherManager;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.server.GRPCHandlerRegister;
 import org.apache.skywalking.oap.server.core.source.SourceReceiver;
 import org.apache.skywalking.oap.server.core.source.SourceReceiverImpl;

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/oal/OALDebugRecorderFactory.java

@@ -21,7 +21,7 @@
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.AbstractDebugRecorder;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.DebugRecorderFactory;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.SessionLimits;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.GateHolder;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;
 

oap-server/server-admin/dsl-debugging/src/main/java/org/apache/skywalking/oap/server/admin/dsl/debugging/oal/OALHolderLookup.java

@@ -21,7 +21,7 @@
 import lombok.RequiredArgsConstructor;
 import org.apache.skywalking.oap.server.admin.dsl.debugging.session.DebugHolderLookup;
 import org.apache.skywalking.oap.server.core.analysis.DispatcherManager;
-import org.apache.skywalking.oap.server.core.classloader.Catalog;
+import org.apache.skywalking.oap.server.core.dsl.Catalog;
 import org.apache.skywalking.oap.server.core.dsl.debug.DebugHolderProvider;
 import org.apache.skywalking.oap.server.core.dsl.debug.GateHolder;
 import org.apache.skywalking.oap.server.core.dsl.debug.RuleKey;