Improve bytebuddy class enhance for retransform classes (#561)

* SWAuxiliaryTypeNamingStrategy
Auxiliary type name pattern: <origin_class_name>$<name_trait>$auxiliary$<auxiliary_type_instance_hash>

* DelegateNamingResolver
Interceptor delegate field name pattern: <name_trait>$delegate$<class_name_hash>$<plugin_define_hash>$<intercept_point_hash>

* SWMethodNameTransformer
Renamed origin method pattern: <name_trait>$original$<method_name>$<method_description_hash>

* SWImplementationContextFactory
Method cache value field pattern: cachedValue$<name_trait>$<origin_class_name_hash>$<field_value_hash>
Accessor method name pattern:  <renamed_origin_method>$accessor$<name_trait>$<origin_class_name_hash>

Here is an example of manipulated enhanced class with new naming policies of auxiliary classes, fields, and methods

```java
 import sample.mybatis.controller.HotelController$sw$auxiliary$19cja42;
 import sample.mybatis.controller.HotelController$sw$auxiliary$p257su0;
 import sample.mybatis.domain.Hotel;
 import sample.mybatis.service.HotelService;

 @RequestMapping(value={"/hotel"})
 @RestController
 public class HotelController
 implements EnhancedInstance {
     @Autowired
     @lazy
     private HotelService hotelService;
     private volatile Object _$EnhancedClassField_ws;

     // Interceptor delegate fields
     public static volatile /* synthetic */ InstMethodsInter sw$delegate$td03673$ain2do0$8im5jm1;
     public static volatile /* synthetic */ InstMethodsInter sw$delegate$td03673$ain2do0$edkmf61;
     public static volatile /* synthetic */ ConstructorInter sw$delegate$td03673$ain2do0$qs9unv1;
     public static volatile /* synthetic */ InstMethodsInter sw$delegate$td03673$fl4lnk1$m3ia3a2;
     public static volatile /* synthetic */ InstMethodsInter sw$delegate$td03673$fl4lnk1$sufrvp1;
     public static volatile /* synthetic */ ConstructorInter sw$delegate$td03673$fl4lnk1$cteu7s1;

     // Origin method cache value field
     private static final /* synthetic */ Method cachedValue$sw$td03673$g5sobj1;

     public HotelController() {
         this(null);
         sw$delegate$td03673$ain2do0$qs9unv1.intercept(this, new Object[0]);
     }

     private /* synthetic */ HotelController(sw.auxiliary.p257su0 p257su02) {
     }

     @GetMapping(value={"city/{cityId}"})
     public Hotel selectByCityId(@PathVariable(value="cityId") int n) {
         // call interceptor with auxiliary type and parameters and origin method object
         return (Hotel)sw$delegate$td03673$ain2do0$8im5jm1.intercept(this, new Object[]{n}, new HotelController$sw$auxiliary$19cja42(this, n), cachedValue$sw$td03673$g5sobj1);
     }

     // Renamed origin method
     private /* synthetic */ Hotel sw$origin$selectByCityId$a8458p3(int cityId) {
/*22*/         return this.hotelService.selectByCityId(cityId);
     }

     // Accessor of renamed origin method, calling from auxiliary type
     final /* synthetic */ Hotel sw$origin$selectByCityId$a8458p3$accessor$sw$td03673(int n) {
         // Calling renamed origin method
         return this.sw$origin$selectByCityId$a8458p3(n);
     }

     @OverRide
     public Object getSkyWalkingDynamicField() {
         return this._$EnhancedClassField_ws;
     }

     @OverRide
     public void setSkyWalkingDynamicField(Object object) {
         this._$EnhancedClassField_ws = object;
     }

     static {
         ClassLoader.getSystemClassLoader().loadClass("org.apache.skywalking.apm.dependencies.net.bytebuddy.dynamic.Nexus").getMethod("initialize", Class.class, Integer.TYPE).invoke(null, HotelController.class, -1072476370);
         // Method object
         cachedValue$sw$td03673$g5sobj1 = HotelController.class.getMethod("selectByCityId", Integer.TYPE);
     }
 }
```

Auxiliary type of Constructor : 
```java
class HotelController$sw$auxiliary$p257su0 {
}
```

Auxiliary type of  `selectByCityId` method: 
```java
class HotelController$sw$auxiliary$19cja42
implements Runnable,
Callable {
    private HotelController argument0;
    private int argument1;

    public Object call() throws Exception {
        return this.argument0.sw$origin$selectByCityId$a8458p3$accessor$sw$td03673(this.argument1);
    }

    @OverRide
    public void run() {
        this.argument0.sw$origin$selectByCityId$a8458p3$accessor$sw$td03673(this.argument1);
    }

    HotelController$sw$auxiliary$19cja42(HotelController hotelController, int n) {
        this.argument0 = hotelController;
        this.argument1 = n;
    }
}
```

Author: kylixs

CHANGES.md

@@ -12,6 +12,7 @@ Release Notes.
 * Fix the conflict between the logging kernel and the JDK threadpool plugin.
 * Fix the thread safety bug of finishing operation for the span named "SpringCloudGateway/sendRequest"
 * Fix NPE in guava-eventbus-plugin.
+* Support re-transform/hot-swap classes with other java agents, and remove the obsolete cache enhanced class feature. 
 
 #### Documentation
 

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Config.java

@@ -25,7 +25,6 @@
 import org.apache.skywalking.apm.agent.core.logging.core.LogOutput;
 import org.apache.skywalking.apm.agent.core.logging.core.ResolverType;
 import org.apache.skywalking.apm.agent.core.logging.core.WriterFactory;
-import org.apache.skywalking.apm.agent.core.plugin.bytebuddy.ClassCacheMode;
 import org.apache.skywalking.apm.util.Length;
 
 /**
@@ -110,19 +109,6 @@ public static class Agent {
          */
         public static boolean IS_OPEN_DEBUGGING_CLASS = false;
 
-        /**
-         * If true, SkyWalking agent will cache all instrumented classes to memory or disk files (decided by class cache
-         * mode), allow other javaagent to enhance those classes that enhanced by SkyWalking agent.
-         */
-        public static boolean IS_CACHE_ENHANCED_CLASS = false;
-
-        /**
-         * The instrumented classes cache mode: MEMORY or FILE MEMORY: cache class bytes to memory, if instrumented
-         * classes is too many or too large, it may take up more memory FILE: cache class bytes in `/class-cache`
-         * folder, automatically clean up cached class files when the application exits
-         */
-        public static ClassCacheMode CLASS_CACHE_MODE = ClassCacheMode.MEMORY;
-
         /**
          * The identifier of the instance
          */

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Constants.java

@@ -32,4 +32,10 @@ public class Constants {
     public static String EVENT_LAYER_NAME = "GENERAL";
 
     public static int NULL_VALUE = 0;
+
+    /**
+     * The name trait for auxiliary type names, field names and method names which generated by ByteBuddy.
+     */
+    public static final String NAME_TRAIT = "sw$";
+
 }

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/bytebuddy/AnnotationTypeNameMatch.java

@@ -55,6 +55,17 @@ public boolean matches(T target) {
         return target.getAnnotationType().asErasure().getName().equals(annotationTypeName);
     }
 
+    /**
+     * To ensure that the hashCode for recreating the XxxInterceptPoint instance is the same as the previous instance,
+     * each ElementMatcher implementation class needs to implement toString() method.
+     */
+    @Override
+    public String toString() {
+        return "AnnotationTypeNameMatch{" +
+                "annotationTypeName='" + annotationTypeName + '\'' +
+                '}';
+    }
+
     /**
      * The static method to create {@link AnnotationTypeNameMatch} This is a delegate method to follow byte-buddy {@link
      * ElementMatcher}'s code style.

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/bytebuddy/ArgumentTypeNameMatch.java

@@ -68,6 +68,18 @@ public boolean matches(MethodDescription target) {
         return false;
     }
 
+    /**
+     * To ensure that the hashCode for recreating the XxxInterceptPoint instance is the same as the previous instance,
+     * each ElementMatcher implementation class needs to implement toString() method.
+     */
+    @Override
+    public String toString() {
+        return "ArgumentTypeNameMatch{" +
+                "index=" + index +
+                ", argumentTypeName='" + argumentTypeName + '\'' +
+                '}';
+    }
+
     /**
      * The static method to create {@link ArgumentTypeNameMatch} This is a delegate method to follow byte-buddy {@link
      * ElementMatcher}'s code style.

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/bytebuddy/CacheableTransformerDecorator.java

@@ -53,6 +53,17 @@ public boolean matches(MethodDescription target) {
         return target.getReturnType().asErasure().getName().equals(returnTypeName);
     }
 
+    /**
+     * To ensure that the hashCode for recreating the XxxInterceptPoint instance is the same as the previous instance,
+     * each ElementMatcher implementation class needs to implement toString() method.
+     */
+    @Override
+    public String toString() {
+        return "ReturnTypeNameMatch{" +
+                "returnTypeName='" + returnTypeName + '\'' +
+                '}';
+    }
+
     /**
      * The static method to create {@link ReturnTypeNameMatch} This is a delegate method to follow byte-buddy {@link
      * ElementMatcher}'s code style.

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/bytebuddy/ReturnTypeNameMatch.java

@@ -21,6 +21,8 @@
 import net.bytebuddy.description.method.MethodDescription;
 import net.bytebuddy.matcher.ElementMatcher;
 
+import java.util.Objects;
+
 /**
  * One of the three "Intercept Point". "Intercept Point" is a definition about where and how intercept happens. In this
  * "Intercept Point", the definition targets class's constructors, and the interceptor.
@@ -41,4 +43,13 @@ public interface ConstructorInterceptPoint {
      * org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceConstructorInterceptor}
      */
     String getConstructorInterceptor();
+
+    /**
+     * To ensure that the hashCode for recreating the XxxInterceptPoint instance is the same as the previous instance,
+     * each ElementMatcher implementation class needs to implement toString() method.
+     * @return hashCode of this intercept point
+     */
+    default int computeHashCode() {
+        return Objects.hash(this.getClass().getName(), this.getConstructorMatcher().toString(), this.getConstructorInterceptor());
+    }
 }

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/interceptor/ConstructorInterceptPoint.java

@@ -21,6 +21,8 @@
 import net.bytebuddy.description.method.MethodDescription;
 import net.bytebuddy.matcher.ElementMatcher;
 
+import java.util.Objects;
+
 /**
  * One of the three "Intercept Point". "Intercept Point" is a definition about where and how intercept happens. In this
  * "Intercept Point", the definition targets class's instance methods, and the interceptor.
@@ -42,4 +44,13 @@ public interface InstanceMethodsInterceptPoint {
     String getMethodsInterceptor();
 
     boolean isOverrideArgs();
+
+    /**
+     * To ensure that the hashCode for recreating the XxxInterceptPoint instance is the same as the previous instance,
+     * each ElementMatcher implementation class needs to implement toString() method.
+     * @return hashCode of this intercept point
+     */
+    default int computeHashCode() {
+        return Objects.hash(this.getClass().getName(), this.getMethodsMatcher().toString(), this.getMethodsInterceptor(), this.isOverrideArgs());
+    }
 }

apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/plugin/interceptor/InstanceMethodsInterceptPoint.java

@@ -21,6 +21,8 @@
 import net.bytebuddy.description.method.MethodDescription;
 import net.bytebuddy.matcher.ElementMatcher;
 
+import java.util.Objects;
+
 /**
  * One of the three "Intercept Point". "Intercept Point" is a definition about where and how intercept happens. In this
  * "Intercept Point", the definition targets class's static methods, and the interceptor.
@@ -42,4 +44,13 @@ public interface StaticMethodsInterceptPoint {
     String getMethodsInterceptor();
 
     boolean isOverrideArgs();
+
+    /**
+     * To ensure that the hashCode for recreating the XxxInterceptPoint instance is the same as the previous instance,
+     * each ElementMatcher implementation class needs to implement toString() method.
+     * @return hashCode of this intercept point
+     */
+    default int computeHashCode() {
+        return Objects.hash(this.getClass().getName(), this.getMethodsMatcher().toString(), this.getMethodsInterceptor(), this.isOverrideArgs());
+    }
 }