Add MaxMind circuit breaker. Finishes #38

pom.xml

@@ -79,6 +79,11 @@
             <artifactId>vertx-redis-client</artifactId>
             <version>3.3.0</version>
         </dependency>
+        <dependency>
+            <groupId>io.vertx</groupId>
+            <artifactId>vertx-circuit-breaker</artifactId>
+            <version>3.3.0</version>
+        </dependency>
 
         <!-- Google Libs -->
         <dependency>

src/main/java/net/frozenorb/apiv3/util/MaxMindUtils.java

@@ -2,6 +2,8 @@ package net.frozenorb.apiv3.util;
 
 import com.google.common.base.Charsets;
 import com.mongodb.async.SingleResultCallback;
+import io.vertx.circuitbreaker.CircuitBreaker;
+import io.vertx.circuitbreaker.CircuitBreakerOptions;
 import io.vertx.core.http.HttpClient;
 import io.vertx.core.http.HttpClientOptions;
 import io.vertx.core.json.JsonObject;
@@ -17,13 +19,23 @@ public class MaxMindUtils {
     private static final String maxMindUserId = APIv3.getConfig().getProperty("maxMind.userId");
     private static final String maxMindLicenseKey = APIv3.getConfig().getProperty("maxMind.maxMindLicenseKey");
     private static final HttpClient httpsClient = APIv3.getVertxInstance().createHttpClient(new HttpClientOptions().setSsl(true).setTrustAll(true));
+    private static final CircuitBreaker breaker;
 
-    public static void getInsights(String ip, SingleResultCallback<MaxMindResult> callback) {
+    // MaxMind likes to randomly not respond, so we take advantage of the circuit breaker pattern to only
-        if (1 == 1) {
+    // check MaxMind periodically (while it's in a non-responsive state) to keep our average response times
-            callback.onResult(null, null);
+    // nice and low.
-            return;
+    static {
+        breaker = CircuitBreaker.create("maxmind-circuit-breaker", APIv3.getVertxInstance(),
+                new CircuitBreakerOptions()
+                        .setMaxFailures(5)
+                        .setTimeout(1000) // 1 second
+                        .setFallbackOnFailure(true)
+                        .setResetTimeout(120_000) // 2 minutes
+        );
     }
 
+    public static void getInsights(String ip, SingleResultCallback<MaxMindResult> callback) {
+        breaker.executeWithFallback((future) -> {
             String authHeader = "Basic " + Base64.getEncoder().encodeToString((maxMindUserId + ":" + maxMindLicenseKey).getBytes(Charsets.UTF_8));
 
             httpsClient.get(443, "geoip.maxmind.com", "/geoip/v2.1/insights/" + ip, (response) -> {
@@ -32,17 +44,23 @@ public class MaxMindUtils {
 
                     try {
                         MaxMindResult maxMindResult = new MaxMindResult(bodyJson);
-                    callback.onResult(maxMindResult, null);
+                        future.complete(maxMindResult);
                     } catch (Exception ignored) {
-                    callback.onResult(null, null);
+                        future.complete(null);
                     }
                 });
 
-            response.exceptionHandler((error) -> callback.onResult(null, error));
+                response.exceptionHandler(future::fail);
             })
             .putHeader("Authorization", authHeader)
-        .setTimeout(1000)
             .end();
+        }, (ignored) -> null).setHandler((result) -> { // The (ignored) -> null section is our fallback, which just returns null (when the breaker is open)
+            if (result.failed()) {
+                callback.onResult(null, result.cause());
+            } else {
+                callback.onResult((MaxMindResult) result.result(), null);
+            }
+        });
     }
 
     public static String getEnglishName(JsonObject source) {