Read cache upon each setting read (#40)

* Read cache upon each setting read

* Update java-ci.yml

.github/workflows/java-ci.yml

@@ -42,7 +42,7 @@ jobs:
     - name: Set up JDK
       uses: actions/setup-java@v3
       with:
-        java-version: 11
+        java-version: 17
         distribution: zulu
         cache: gradle
 

gradle.properties

@@ -1 +1 @@
-version=8.3.0
+version=8.4.0

src/main/java/com/configcat/ConfigService.java

@@ -26,7 +26,7 @@ public class ConfigService implements Closeable {
     private ScheduledExecutorService pollScheduler;
     private ScheduledExecutorService initScheduler;
     private CompletableFuture<Result<Entry>> runningTask;
-    private boolean initialized = false;
+    private final AtomicBoolean initialized = new AtomicBoolean(false);
     private final AtomicBoolean closed = new AtomicBoolean(false);
     private final AtomicBoolean offline;
     private final ReentrantLock lock = new ReentrantLock(true);
@@ -57,8 +57,7 @@ public ConfigService(String sdkKey,
             this.initScheduler.schedule(() -> {
                 lock.lock();
                 try {
-                    if (!initialized) {
-                        initialized = true;
+                    if (initialized.compareAndSet(false, true)) {
                         this.configCatHooks.invokeOnClientReady();
                         String message = ConfigCatLogMessages.getAutoPollMaxInitWaitTimeReached(autoPollingMode.getMaxInitWaitTimeSeconds());
                         this.logger.warn(4200, message);
@@ -75,8 +74,7 @@ public ConfigService(String sdkKey,
     }
 
     private void setInitialized() {
-        if (!initialized) {
-            initialized = true;
+        if (initialized.compareAndSet(false, true)) {
             configCatHooks.invokeOnClientReady();
         }
     }
@@ -107,43 +105,34 @@ public CompletableFuture<SettingResult> getSettings() {
                             ? new SettingResult(entryResult.value().getConfig().getEntries(), entryResult.value().getFetchTime())
                             : SettingResult.EMPTY);
         } else {
-            return fetchIfOlder(Constants.DISTANT_PAST, true)
+            return fetchIfOlder(Constants.DISTANT_PAST, initialized.get()) // If we are initialized, we prefer the cached results
                     .thenApply(entryResult -> !entryResult.value().isEmpty()
                             ? new SettingResult(entryResult.value().getConfig().getEntries(), entryResult.value().getFetchTime())
                             : SettingResult.EMPTY);
         }
 
     }
 
-    private CompletableFuture<Result<Entry>> fetchIfOlder(long time, boolean preferCached) {
+    private CompletableFuture<Result<Entry>> fetchIfOlder(long threshold, boolean preferCached) {
         lock.lock();
         try {
             // Sync up with the cache and use it when it's not expired.
-            if (cachedEntry.isEmpty() || cachedEntry.getFetchTime() > time) {
-                Entry fromCache = readCache();
-                if (!fromCache.isEmpty() && !fromCache.getETag().equals(cachedEntry.getETag())) {
-                    configCatHooks.invokeOnConfigChanged(fromCache.getConfig().getEntries());
-                    cachedEntry = fromCache;
-                }
-                // Cache isn't expired
-                if (cachedEntry.getFetchTime() > time) {
-                    setInitialized();
-                    return CompletableFuture.completedFuture(Result.success(cachedEntry));
-                }
+            Entry fromCache = readCache();
+            if (!fromCache.isEmpty() && !fromCache.getETag().equals(cachedEntry.getETag())) {
+                configCatHooks.invokeOnConfigChanged(fromCache.getConfig().getEntries());
+                cachedEntry = fromCache;
             }
-            // Use cache anyway (get calls on auto & manual poll must not initiate fetch).
-            // The initialized check ensures that we subscribe for the ongoing fetch during the
-            // max init wait time window in case of auto poll.
-            if (preferCached && initialized) {
+            // Cache isn't expired
+            if (cachedEntry.getFetchTime() > threshold) {
+                setInitialized();
                 return CompletableFuture.completedFuture(Result.success(cachedEntry));
             }
-            // If we are in offline mode we are not allowed to initiate fetch.
-            if (offline.get()) {
+            // If we are in offline mode or the caller prefers cached values, do not initiate fetch.
+            if (offline.get() || preferCached) {
                 return CompletableFuture.completedFuture(Result.success(cachedEntry));
             }
 
-            if (runningTask == null) {
-                // No fetch is running, initiate a new one.
+            if (runningTask == null) { // No fetch is running, initiate a new one.
                 runningTask = new CompletableFuture<>();
                 configFetcher.fetchAsync(cachedEntry.getETag())
                         .thenAccept(this::processResponse);

src/main/java/com/configcat/Constants.java

@@ -8,5 +8,5 @@ private Constants() { /* prevent from instantiation*/ }
     static final String CONFIG_JSON_NAME = "config_v5.json";
     static final String SERIALIZATION_FORMAT_VERSION = "v2";
 
-    static final String VERSION = "8.3.0";
+    static final String VERSION = "8.4.0";
 }

src/test/java/com/configcat/AutoPollingPolicyTest.java → src/test/java/com/configcat/AutoPollingTest.java

@@ -17,9 +17,9 @@
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.mock;
 
-public class AutoPollingPolicyTest {
+public class AutoPollingTest {
     private MockWebServer server;
-    private final ConfigCatLogger logger = new ConfigCatLogger(LoggerFactory.getLogger(AutoPollingPolicyTest.class), LogLevel.WARNING);
+    private final ConfigCatLogger logger = new ConfigCatLogger(LoggerFactory.getLogger(AutoPollingTest.class), LogLevel.WARNING);
     private static final String TEST_JSON = "{ f: { fakeKey: { v: %s, p: [] ,r: [] } } }";
 
     @BeforeEach

src/test/java/com/configcat/Helpers.java

@@ -10,6 +10,12 @@ static String cacheValueFromConfigJson(String json) {
         return entry.serialize();
     }
 
+    static String cacheValueFromConfigJsonWithEtag(String json, String etag) {
+        Config config = Utils.gson.fromJson(json, Config.class);
+        Entry entry = new Entry(config, etag, json, System.currentTimeMillis());
+        return entry.serialize();
+    }
+
     static void waitFor(Supplier<Boolean> predicate) throws InterruptedException {
         waitFor(3000, predicate);
     }

src/test/java/com/configcat/LazyLoadingPolicyTest.java → src/test/java/com/configcat/LazyLoadingTest.java

@@ -14,10 +14,10 @@
 
 import static org.junit.jupiter.api.Assertions.*;
 
-public class LazyLoadingPolicyTest {
+public class LazyLoadingTest {
     private ConfigService configService;
     private MockWebServer server;
-    private final ConfigCatLogger logger = new ConfigCatLogger(LoggerFactory.getLogger(LazyLoadingPolicyTest.class));
+    private final ConfigCatLogger logger = new ConfigCatLogger(LoggerFactory.getLogger(LazyLoadingTest.class));
     private static final String TEST_JSON = "{ f: { fakeKey: { v: %s, p: [] ,r: [] } } }";
 
     @BeforeEach
@@ -146,6 +146,27 @@ void testCacheExpirationRespectedInTTLCalc304() throws InterruptedException, Exe
         assertEquals(1, this.server.getRequestCount());
     }
 
+    @Test
+    void testCacheTTLRespectsExternalCache() throws Exception {
+        this.server.enqueue(new MockResponse().setResponseCode(200).setBody(String.format(TEST_JSON, "test-remote")));
+
+        ConfigCache cache = new SingleValueCache(Helpers.cacheValueFromConfigJsonWithEtag(String.format(TEST_JSON, "test-local"), "etag"));
+
+        PollingMode mode = PollingModes
+                .lazyLoad(1);
+        ConfigFetcher fetcher = new ConfigFetcher(new OkHttpClient.Builder().build(), logger, "", this.server.url("/").toString(), false, mode.getPollingIdentifier());
+        ConfigService service = new ConfigService("", fetcher, mode, cache, logger, false, new ConfigCatHooks());
+
+        assertEquals("test-local", service.getSettings().get().settings().get("fakeKey").getValue().getAsString());
+        assertEquals(0, this.server.getRequestCount());
+        Thread.sleep(1000);
+
+        cache.write("", Helpers.cacheValueFromConfigJsonWithEtag(String.format(TEST_JSON, "test-local2"), "etag2"));
+        assertEquals("test-local2", service.getSettings().get().settings().get("fakeKey").getValue().getAsString());
+
+        assertEquals(0, this.server.getRequestCount());
+    }
+
     @Test
     void testOnlineOffline() throws Exception {
         this.server.enqueue(new MockResponse().setResponseCode(200).setBody(String.format(TEST_JSON, "test")));

src/test/java/com/configcat/ManualPollingPolicyTest.java → src/test/java/com/configcat/ManualPollingTest.java

@@ -15,10 +15,10 @@
 import static org.junit.jupiter.api.Assertions.*;
 
 
-public class ManualPollingPolicyTest {
+public class ManualPollingTest {
     private ConfigService configService;
     private MockWebServer server;
-    private final ConfigCatLogger logger = new ConfigCatLogger(LoggerFactory.getLogger(ManualPollingPolicyTest.class));
+    private final ConfigCatLogger logger = new ConfigCatLogger(LoggerFactory.getLogger(ManualPollingTest.class));
     private static final String TEST_JSON = "{ f: { fakeKey: { v: %s, p: [] ,r: [] } } }";
 
     @BeforeEach