Ensure that identity caches are separate (#129)

Author: matthewelwell

src/main/java/com/flagsmith/FlagsmithApiWrapper.java

@@ -174,9 +174,11 @@ public Flags identifyUserWithTraits(
   ) {
     assertValidUser(identifier);
     Flags flags = null;
+    String cacheKey = null;
 
-    if (getCache() != null && getCache().getEnvFlagsCacheKey() != null) {
-      flags = getCache().getIfPresent(getCache().getEnvFlagsCacheKey());
+    if (getCache() != null) {
+      cacheKey = getCache().getIdentityFlagsCacheKey(identifier);
+      flags = getCache().getIfPresent(cacheKey);
 
       if (flags != null) {
         return flags;
@@ -218,9 +220,9 @@ public Flags identifyUserWithTraits(
           getConfig().getFlagsmithFlagDefaults()
       );
 
-      if (getCache() != null) {
-        getCache().getCache().put("identifier" + identifier, flags);
-        logger.info("Got feature flags for flags = {} and cached.", flags);
+      if (cacheKey != null) {
+        getCache().getCache().put(cacheKey, flags);
+        logger.info("Cached flags for identity {}.", identifier);
       }
 
     } catch (TimeoutException ie) {

src/main/java/com/flagsmith/config/FlagsmithCacheConfig.java

@@ -206,6 +206,11 @@ public String getEnvFlagsCacheKey() {
       return this.envFlagsCacheKey;
     }
 
+    @Override
+    public String getIdentityFlagsCacheKey(String identifier) {
+      return "identity" + identifier;
+    }
+
     @Override
     public Cache<String, Flags> getCache() {
       return cache;

src/main/java/com/flagsmith/interfaces/FlagsmithCache.java

@@ -69,6 +69,13 @@ public interface FlagsmithCache {
    */
   String getEnvFlagsCacheKey();
 
+  /**
+   * Returns the cache key for a given identity.
+   *
+   * @return string
+   */
+  String getIdentityFlagsCacheKey(String identifier);
+
   /**
    * Returns the Cache instance.
    *

src/test/java/com/flagsmith/FlagsmithApiWrapperCachingTest.java

@@ -156,8 +156,11 @@ public void identifyUserWithTraits_nullUserIdentifier() {
   public void identifyUserWithTraits_fetchFlagsFromFlagsmithAndStoreThemInCache_whenCacheEmpty() {
     // Arrange
     String identifier = "test-user";
+    String expectedCacheKey = "identity" + identifier;
     final ArrayList<TraitModel> traits = new ArrayList<>();
 
+    when(flagsmithCacheImpl.getIdentityFlagsCacheKey(identifier)).thenReturn(expectedCacheKey);
+
     final FlagsAndTraitsResponse flagsAndTraitsResponse = new FlagsAndTraitsResponse();
     when(requestProcessor.executeAsync(any(), any(), any()))
         .thenReturn(FlagsmithTestHelper.futurableReturn(flagsAndTraitsResponse));
@@ -170,6 +173,11 @@ public void identifyUserWithTraits_fetchFlagsFromFlagsmithAndStoreThemInCache_wh
     // Assert
     verify(requestProcessor, times(1)).executeAsync(any(), any(), any());
     assertEquals(newFlagsList(new ArrayList<>()), actualUserFlagsAndTraits);
+
+    verify(flagsmithCacheImpl, times(1)).getIfPresent(expectedCacheKey);
+
+    assertEquals(1, cache.estimatedSize());
+    assertEquals(cache.getIfPresent(expectedCacheKey), actualUserFlagsAndTraits);
   }
 
   @Test