Support configurable latency.

Added the stack frame is now part of addRandomChanceOfFailure() because it is needed for all branching logic.

src/main/java/uk/co/probablyfine/bytemonkey/ByteMonkeyClassTransformer.java

@@ -18,6 +18,7 @@ public class ByteMonkeyClassTransformer implements ClassFileTransformer {
     private static Double activationRatio = 1.0;
     private static Random random = new Random();
     private final Pattern filter;
+    private final long latency;
 
     public ByteMonkeyClassTransformer(String args) {
         Map<String, String> configuration = Arrays
@@ -30,7 +31,8 @@ public ByteMonkeyClassTransformer(String args) {
             );
 
         this.mode = OperationMode.fromLowerCase(configuration.getOrDefault("mode", OperationMode.FAULT.name()));
-        this.filter = Pattern.compile(configuration.getOrDefault("filter",".*"));
+        this.filter = Pattern.compile(configuration.getOrDefault("filter", ".*"));
+        this.latency = Long.valueOf(configuration.getOrDefault("latency","100"));
         activationRatio = Double.valueOf(configuration.getOrDefault("rate","1"));
 
     }
@@ -81,9 +83,9 @@ private Optional<InsnList> createNewInstructions(MethodNode method) {
     }
 
     private Optional<InsnList> createLatency() {
-        InsnList list = new InsnList();
+        final InsnList list = new InsnList();
 
-        list.add(new LdcInsnNode(2000L));
+        list.add(new LdcInsnNode(this.latency));
         list.add(new MethodInsnNode(Opcodes.INVOKESTATIC, "java/lang/Thread", "sleep", "(J)V", false));
 
         return Optional.of(addRandomChanceOfFailure(list));
@@ -108,12 +110,6 @@ private Optional<InsnList> throwException(List<String> exceptionsThrown) {
 
         list.add(new InsnNode(Opcodes.ATHROW));
 
-        list.add(new FrameNode(
-            Opcodes.F_APPEND,   // append to the last stack frame
-            0, new Object[] {}, // no local variables here
-            0, new Object[] {}  // no stack either!
-        ));
-
         return Optional.of(addRandomChanceOfFailure(list));
     }
 
@@ -131,7 +127,15 @@ private InsnList addRandomChanceOfFailure(final InsnList newInstructions) {
         ));
 
         list.add(new JumpInsnNode(Opcodes.IFEQ, originalCodeLabel));
+
         list.add(newInstructions);
+
+        list.add(new FrameNode(
+            Opcodes.F_APPEND,   // append to the last stack frame
+            0, new Object[] {}, // no local variables here
+            0, new Object[] {}  // no stack either!
+        ));
+
         list.add(originalCodeLabel);
 
         return list;

src/main/java/uk/co/probablyfine/bytemonkey/testfiles/TestObject.java

@@ -10,4 +10,8 @@ public void printSomething() throws IOException {
     public void printSomethingElse() throws IllegalStateException {
         System.out.println("Goodbye!");
     }
+
+    public void safePrint() {
+        System.out.println("Hi!");
+    }
 }

src/test/java/uk/co/probablyfine/bytemonkey/latency/Rate100Test.java

@@ -0,0 +1,34 @@
+package uk.co.probablyfine.bytemonkey.latency;
+
+import com.ea.agentloader.AgentLoader;
+import org.junit.Test;
+import uk.co.probablyfine.bytemonkey.ByteMonkeyAgent;
+import uk.co.probablyfine.bytemonkey.testfiles.TestObject;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertTrue;
+
+public class Rate100Test {
+
+    @Test
+    public void shouldThrowExceptionWhenInstrumented_throwPercentageIs100() throws IOException {
+        AgentLoader.loadAgentClass(
+            ByteMonkeyAgent.class.getName(),
+            "mode:latency,rate:1,latency:200,filter:uk/co/probablyfine/bytemonkey/testfiles"
+        );
+
+        long timeTaken = timed(new TestObject()::safePrint);
+
+        assertTrue("Actually took "+timeTaken+"ms", timeTaken >= 200 && timeTaken < 300);
+    }
+
+    public static long timed(Runnable runnable) {
+        long startTime = System.currentTimeMillis();
+
+        runnable.run();
+
+        return System.currentTimeMillis() - startTime;
+    }
+
+}