121 lines
4 KiB
Java
121 lines
4 KiB
Java
package unit;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.LinkedHashSet;
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import java.util.List;
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import java.util.Set;
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/**
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* camel-0001: InternalRouteStartupManager.doStartOrResumeRouteConsumers
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*
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* Defect: routeInputs is ArrayList<Endpoint>. Each iteration calls
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* routeInputs.contains(endpoint) → O(R) inside an O(R) outer loop = O(R²).
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*
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* Fix: use LinkedHashSet<Endpoint> for O(1) contains().
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*/
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public class RouteStartupAlgorithm {
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// --- Slow path: ArrayList.contains() in loop ---
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static long slowStartupCheck(int routeCount) {
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long ops = 0;
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List<String> routeInputs = new ArrayList<>();
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for (int i = 0; i < routeCount; i++) {
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String endpoint = "endpoint-" + i;
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// Simulate: if (!doCheckMultipleConsumerSupportClash(endpoint, routeInputs))
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// doCheckMultipleConsumerSupportClash calls routeInputs.contains(endpoint)
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ops++;
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boolean clash = routeInputs.contains(endpoint); // O(i) scan
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if (clash) {
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throw new RuntimeException("unexpected clash at " + i);
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}
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// Simulate existingEndpoints rebuild each iteration
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List<String> existingEndpoints = new ArrayList<>();
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for (int j = 0; j < i; j++) {
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existingEndpoints.add("endpoint-" + j);
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ops++;
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}
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// contains check on existingEndpoints
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ops++;
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boolean existingClash = existingEndpoints.contains(endpoint); // O(i) scan
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if (existingClash) {
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throw new RuntimeException("unexpected existing clash at " + i);
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}
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routeInputs.add(endpoint);
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}
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return ops;
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}
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// --- Fast path: LinkedHashSet.contains() in loop ---
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static long fastStartupCheck(int routeCount) {
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long ops = 0;
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Set<String> routeInputs = new LinkedHashSet<>();
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Set<String> existingEndpointsSet = new LinkedHashSet<>();
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for (int i = 0; i < routeCount; i++) {
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String endpoint = "endpoint-" + i;
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// O(1) contains
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ops++;
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boolean clash = routeInputs.contains(endpoint);
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if (clash) {
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throw new RuntimeException("unexpected clash at " + i);
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}
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// No need to rebuild existingEndpoints; maintain incrementally
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ops++;
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boolean existingClash = existingEndpointsSet.contains(endpoint);
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if (existingClash) {
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throw new RuntimeException("unexpected existing clash at " + i);
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}
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routeInputs.add(endpoint);
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existingEndpointsSet.add(endpoint);
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}
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return ops;
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}
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static void runTest(String label, int N, long slowOps, long fastOps) {
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double ratio = (double) slowOps / fastOps;
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boolean pass = ratio >= 10.0;
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System.out.printf(" %-12s N=%-5d slow=%,7d fast=%,5d ratio=%5.1fx %s%n",
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label, N, slowOps, fastOps, ratio, pass ? "PASS" : "FAIL");
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if (!pass) {
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throw new AssertionError("Ratio " + ratio + " < 10x threshold at N=" + N);
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}
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}
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public static void main(String[] args) {
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System.out.println("camel-0001: RouteStartupAlgorithm");
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System.out.println(" Defect: ArrayList.contains() in O(R) loop → O(R²)");
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System.out.println(" Fix: LinkedHashSet.contains() → O(R)");
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System.out.println();
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int[] sizes = {100, 300, 500};
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int passed = 0;
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int total = sizes.length;
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for (int N : sizes) {
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long slowOps = slowStartupCheck(N);
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long fastOps = fastStartupCheck(N);
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try {
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runTest("route-startup", N, slowOps, fastOps);
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passed++;
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} catch (AssertionError e) {
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System.out.println(" FAIL: " + e.getMessage());
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}
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}
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System.out.println();
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System.out.println(passed + "/" + total + " PASS");
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if (passed < total) {
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System.exit(1);
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}
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}
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}
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