Allow GsonBuilder to be passed in and used through Analytics and AnalyticsClient (#446)

Co-authored-by: Louis Lepper <llepper2@atlassian.com>

Author: louislepper

analytics/src/main/java/com/segment/analytics/Analytics.java

@@ -149,6 +149,7 @@ public static class Builder {
     private List<Callback> callbacks;
     private int queueCapacity;
     private boolean forceTlsV1 = false;
+    private GsonBuilder gsonBuilder;
 
     Builder(String writeKey) {
       if (writeKey == null || writeKey.trim().length() == 0) {
@@ -248,6 +249,20 @@ public Builder queueCapacity(int capacity) {
       this.queueCapacity = capacity;
       return this;
     }
+
+    public Builder gsonBuilder(GsonBuilder gsonBuilder) {
+      if (gsonBuilder == null) {
+        throw new NullPointerException("Null gsonBuilder");
+      }
+
+      if (this.gsonBuilder != null) {
+        throw new IllegalStateException("gsonBuilder is already registered.");
+      }
+
+      this.gsonBuilder = gsonBuilder;
+      return this;
+    }
+
     /** Set the queueSize at which flushes should be triggered. */
     @Beta
     public Builder flushQueueSize(int flushQueueSize) {
@@ -341,11 +356,15 @@ public Builder forceTlsVersion1() {
 
     /** Create a {@link Analytics} client. */
     public Analytics build() {
-      Gson gson =
-          new GsonBuilder() //
-              .registerTypeAdapterFactory(new AutoValueAdapterFactory()) //
-              .registerTypeAdapter(Date.class, new ISO8601DateAdapter()) //
-              .create();
+      if (gsonBuilder == null) {
+        gsonBuilder = new GsonBuilder();
+      }
+
+      gsonBuilder
+          .registerTypeAdapterFactory(new AutoValueAdapterFactory())
+          .registerTypeAdapter(Date.class, new ISO8601DateAdapter());
+
+      Gson gson = gsonBuilder.create();
 
       if (endpoint == null) {
         if (uploadURL != null) {
@@ -450,7 +469,8 @@ public void log(String message) {
               threadFactory,
               networkExecutor,
               callbacks,
-              writeKey);
+              writeKey,
+              gson);
 
       return new Analytics(analyticsClient, messageTransformers, messageInterceptors, log);
     }

analytics/src/main/java/com/segment/analytics/internal/AnalyticsClient.java

@@ -40,7 +40,7 @@ public class AnalyticsClient {
   private static final int BATCH_MAX_SIZE = 1024 * 500;
   private static final int MSG_MAX_SIZE = 1024 * 32;
   private static final Charset ENCODING = StandardCharsets.UTF_8;
-  private static Gson gsonInstance;
+  private Gson gsonInstance;
   private static final String instanceId = UUID.randomUUID().toString();
 
   static {
@@ -80,7 +80,8 @@ public static AnalyticsClient create(
       ThreadFactory threadFactory,
       ExecutorService networkExecutor,
       List<Callback> callbacks,
-      String writeKey) {
+      String writeKey,
+      Gson gsonInstance) {
     return new AnalyticsClient(
         new LinkedBlockingQueue<Message>(queueCapacity),
         uploadUrl,
@@ -94,7 +95,8 @@ public static AnalyticsClient create(
         networkExecutor,
         callbacks,
         new AtomicBoolean(false),
-        writeKey);
+        writeKey,
+        gsonInstance);
   }
 
   public AnalyticsClient(
@@ -110,7 +112,8 @@ public AnalyticsClient(
       ExecutorService networkExecutor,
       List<Callback> callbacks,
       AtomicBoolean isShutDown,
-      String writeKey) {
+      String writeKey,
+      Gson gsonInstance) {
     this.messageQueue = messageQueue;
     this.uploadUrl = uploadUrl;
     this.service = service;
@@ -123,6 +126,7 @@ public AnalyticsClient(
     this.networkExecutor = networkExecutor;
     this.isShutDown = isShutDown;
     this.writeKey = writeKey;
+    this.gsonInstance = gsonInstance;
 
     this.currentQueueSizeInBytes = 0;
 
@@ -141,24 +145,10 @@ public void run() {
         TimeUnit.MILLISECONDS);
   }
 
-  /**
-   * Creating GSON object everytime we check the size seems costly
-   *
-   * @return gson instance
-   */
-  public Gson getGsonInstance() {
-    if (gsonInstance == null) {
-      gsonInstance = new Gson();
-    }
-    return gsonInstance;
-  }
-
   public int messageSizeInBytes(Message message) {
-    Gson gson = getGsonInstance();
-    String stringifiedMessage = gson.toJson(message);
+    String stringifiedMessage = gsonInstance.toJson(message);
 
-    int sizeInBytes = stringifiedMessage.getBytes(ENCODING).length;
-    return sizeInBytes;
+    return stringifiedMessage.getBytes(ENCODING).length;
   }
 
   private Boolean isBackPressuredAfterSize(int incomingSize) {
@@ -269,7 +259,7 @@ public void run() {
       LinkedList<Message> messages = new LinkedList<>();
       AtomicInteger currentBatchSize = new AtomicInteger();
       boolean batchSizeLimitReached = false;
-      int contextSize = getGsonInstance().toJson(CONTEXT).getBytes(ENCODING).length;
+      int contextSize = gsonInstance.toJson(CONTEXT).getBytes(ENCODING).length;
       try {
         while (!stop) {
           Message message = messageQueue.take();

analytics/src/test/java/com/segment/analytics/AnalyticsBuilderTest.java

@@ -7,6 +7,7 @@
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 
+import com.google.gson.GsonBuilder;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
@@ -167,6 +168,34 @@ public void buildsWithValidInterceptor() {
     assertThat(analytics).isNotNull();
   }
 
+  @Test
+  public void nullGsonBuilder() {
+    try {
+      builder.gsonBuilder(null);
+      fail("Should fail for null gsonBuilder");
+    } catch (NullPointerException e) {
+      assertThat(e).hasMessage("Null gsonBuilder");
+    }
+  }
+
+  @Test
+  public void duplicateGsonBuilder() {
+    GsonBuilder gsonBuilder = new GsonBuilder();
+    try {
+      builder.gsonBuilder(gsonBuilder).gsonBuilder(gsonBuilder);
+      fail("Should fail for duplicate gsonBuilder");
+    } catch (IllegalStateException e) {
+      assertThat(e).hasMessage("gsonBuilder is already registered.");
+    }
+  }
+
+  @Test
+  public void buildsWithValidGsonBuilder() {
+    GsonBuilder gsonBuilder = new GsonBuilder();
+    Analytics analytics = builder.gsonBuilder(gsonBuilder).build();
+    assertThat(analytics).isNotNull();
+  }
+
   @Test
   public void invalidFlushQueueSize() {
     try {

analytics/src/test/java/com/segment/analytics/internal/AnalyticsClientTest.java

@@ -16,6 +16,7 @@
 import static org.mockito.Mockito.when;
 import static org.mockito.MockitoAnnotations.openMocks;
 
+import com.google.gson.Gson;
 import com.segment.analytics.Callback;
 import com.segment.analytics.Log;
 import com.segment.analytics.TestUtils.MessageBuilderTest;
@@ -105,7 +106,8 @@ AnalyticsClient newClient() {
         networkExecutor,
         Collections.singletonList(callback),
         isShutDown,
-        writeKey);
+        writeKey,
+        new Gson());
   }
 
   @Test
@@ -293,7 +295,8 @@ public void flushHowManyTimesNecessaryToStayWithinLimit() throws InterruptedExce
             networkExecutor,
             Collections.singletonList(callback),
             isShutDown,
-            writeKey);
+            writeKey,
+            new Gson());
 
     Map<String, String> properties = new HashMap<String, String>();
 
@@ -868,7 +871,8 @@ public void submitBatchBelowThreshold() throws InterruptedException, IllegalArgu
             networkExecutor,
             Collections.singletonList(callback),
             isShutDown,
-            writeKey);
+            writeKey,
+            new Gson());
 
     Map<String, String> properties = new HashMap<String, String>();
     properties.put("property3", generateDataOfSizeSpecialChars(MAX_MSG_SIZE, true));
@@ -909,7 +913,8 @@ public void submitBatchAboveThreshold() throws InterruptedException, IllegalArgu
             networkExecutor,
             Collections.singletonList(callback),
             isShutDown,
-            writeKey);
+            writeKey,
+            new Gson());
 
     Map<String, String> properties = new HashMap<String, String>();
     properties.put("property3", generateDataOfSizeSpecialChars(MAX_MSG_SIZE, true));
@@ -949,7 +954,8 @@ public void submitManySmallMessagesBatchAboveThreshold() throws InterruptedExcep
             networkExecutor,
             Collections.singletonList(callback),
             isShutDown,
-            writeKey);
+            writeKey,
+            new Gson());
 
     Map<String, String> properties = new HashMap<String, String>();
     properties.put("property3", generateDataOfSizeSpecialChars(1024 * 8, true));