1000 years of productivity: the JRebel story

Transcript

2. 1000 years of productivity The JRebel Story
3. JRebel product manager at ZeroTurnaround Java, 10+ years Interested in developer tooling @antonarhipov
6. Make a change Compile Build Deploy Observe the result Take some coffee Avg: 3 min
7. state external serialisable temporary derivative
8. How to reload a single class preserving the state?
9. Class Loader MyClass MyClass instance New Class Loader MyClass’ MyClass’ instance state
10. How to reload web application? (and preserve state)
11. Classes Libraries OldClassLoader NewClassLoader Sevlet New Classes New Libraries Sevlet Session Session init() App State App State Serialize/deserialize
12. OldClassLoader NewClassLoader Sevlet New Classes New Libraries Sevlet Session Session App State App State
13. Class loaders are good for isolation, but suck at reloading the code … (and perfect for memory leaks)
14. Hello, HotSwap! Hotswapping methods since 2002
15. M. Dmitriev. Safe class and data evolution in large and long-lived java[tm] applications. Technical report, Mountain View, CA, 2001.
16. Hello, JRebel! Improving HotSwap since 2007
17. Demo Time!
18. HotSwap JRebel Changing method bodies Adding/removing methods Adding/removing constructors Adding/removing fields Adding/removing annotations Changing superclass Adding/removing interfaces
19. How does it work???
21. The engine
22. ClassA +field1 +field2 +field3 +method1(n:int) +method2(s:String) +method3(z:double) ClassA +field1 +field2 +field3 +proxy methods ClassA0 +method1(n:int) +method2(s:String) +method3(z:double) Transformer
23. public class C extends X {! int y = 5;! int method1(int x) {! return x + y;! }! void method2(String s) {! System.out.println(s);! }! }!
24. public class C extends X {! int y = 5;! int method1(int x) {! Object[] o = new Object[1];! o[0] = x;! return Runtime.redirect(this, o, "C", "method1", "(I)I");! }! void method2(String s) {! Object[] o = new Object[1];! o[0] = s;! return Runtime.redirect(! this, o, "C", "method2", "(Ljava/lang/String;)V");! }! }
25. public abstract class C0 {! public static int method1(C c, int x) {! int tmp1 = Runtime.getFieldValue(c, "C", "y", "I");! return x + tmp1;! }! public static void method2(C c, String s) {! PrintStream tmp1 = Runtime.getFieldValue(! null, "java/lang/System", "out", "Ljava/io/PrintStream;");! Object[] o = new Object[1];! o[0] = s;! Runtime.redirect(! tmp1, o, "java/io/PrintStream;", "println", ! "(Ljava/lang/String;)V");! }! }!
26. public class C extends X {! int y = 5;! int method1(int x) {! return x + y;! }! //...! }! public class C extends X {! int y = 5;! int z() {! return 10;! }! int method1(int x) {! return x + y + z();! }! //...! }
27. public class C1 {! public static int z(C c) {! return 10;! }! public static int method1(C c, int x) {! int tmp1 = Runtime.getFieldValue(c, "C", "y", "I");! int tmp2 = Runtime.redirect(c, null, "C", "z", "(V)I");! return x + tmp1 + tmp2;! }! //...! }
29. static { } Adding new static fields Removing static fields Changing values of static fields Factories etc
30. “package” visibility package -> public -> package
31. package a;! public class A { ! int say() {return 1;}! }! ! ! package a;! class Test {! public static void main(String args[]) {! a.A a = new b.B();! System.out.println(a.say());! }! } package b;! public class B extends a.A {! int say() {return 2;}! }! !
32. concurrency synchronized volatile Object.wait() Object.notify()
33. serialization Serializable Externalizable transient
34. reflection Class, Method, Field, ! ! Constructor, Proxy
35. The Ecosystem
37. Javassist: binary patching for fun and profit
38. import java.lang.instrument.ClassFileTransformer;! import java.lang.instrument.Instrumentation;! ! public class Agent {! public static void premain(String args, Instrumentation inst)! throws Exception {! inst.addTransformer(new ClassFileTransformer { });! }! } java –javaagent:agent.jar … META-INF/MANIFEST.MF Premain-Class: Agent
39. new ClassFileTransformer() {! public byte[] transform(ClassLoader loader, ! String className,! Class<?>classBeingRedefined,! ProtectionDomain protectionDomain, ! byte[] classfileBuffer){! ! ClassPool cp = ClassPool.getDefault();! CtClass ct = cp.makeClass(new ! ByteArrayInputStream(classfileBuffer));! ! transformClass(ct, cp); ! ! return ct.toBytecode();! }! }!
40. new ClassFileTransformer() {! public byte[] transform(ClassLoader loader, ! String className,! Class<?>classBeingRedefined,! ProtectionDomain protectionDomain, ! byte[] classfileBuffer){! ! ClassPool cp = ClassPool.getDefault();! CtClass ct = cp.makeClass(new ! ByteArrayInputStream(classfileBuffer));! ! transformClass(ct, cp); ! ! return ct.toBytecode();! }! }!
41. Javassist demo
42. JRebel Plugins
43. @Path(“/”) public String foo() { return “Foo”; } @Path(“/foobar”) public String foo() { return “FooBar”; } JRebel core JRebel Spring plugin
44. THE IMPACT
45. http://zeroturnaround.com/company/case-studies/ “Team velocity was increased by 40.6%, and according to t-test it was a statistically significant difference.” “Netty and Spring together with JRebel is real pleasure to work with. The value of time saved is over 50% of my development time.”
46. Questions? @antonarhipov
48. Credits https://www.flickr.com/photos/smemon/4556099850/ https://www.flickr.com/photos/gforsythe/10173857405 https://www.flickr.com/photos/dkshots/6967173295 https://www.flickr.com/photos/reckless_sniper/4545673070 https://www.flickr.com/photos/omcoc/8350510425 https://www.flickr.com/photos/bufivla/3619927485 https://www.flickr.com/photos/39747297@N05/5229733647 http://leadershipelements.files.wordpress.com/2014/01/square-peg-round-hole.jpg