feat: Wait Till Cache is ready (#73)

* feat: Wait Till Cache is ready During the Cache client creation, do a gets to determine if the cache is ready and available for use. This will allow us to fail early at Cache Client creation rather than at the time of doing gets/sets. * update as per review feedback * fix build * faster retries * Update exception handling * update exception handling
momentohq · Oct 5, 2021 · ab43e80 · ab43e80
1 parent f8e8d1d
commit ab43e80
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Showing 3 changed files with 54 additions and 64 deletions.
diff --git a/momento-sdk/src/intTest/java/momento/sdk/CacheTest.java b/momento-sdk/src/intTest/java/momento/sdk/CacheTest.java
@@ -28,7 +28,6 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 final class CacheTest {
@@ -198,54 +197,28 @@ private static void testMissHappyPathInternal(Cache client) {
 
   @Test
   void testBadAuthToken() {
-    Cache badCredClient = getCache("BAD_TOKEN", "dummy", Optional.empty());
-    testBadAuthToken(badCredClient);
-  }
-
-  @Test
-  void testBadAuthTokenWithTracing() throws Exception {
-    startIntegrationTestOtel();
-    OpenTelemetrySdk openTelemetry = setOtelSDK();
-    Cache client = getCache("BAD_TOKEN", "dummy", Optional.of(openTelemetry));
-    testBadAuthToken(client);
-    // To accommodate for delays in tracing logs to appear in docker
-    Thread.sleep(1000);
-    verifySetTrace("1");
-    verifyGetTrace("1");
-  }
-
-  private static void testBadAuthToken(Cache badCredClient) {
-    // Bad Auth for Get
-    assertThrows(PermissionDeniedException.class, () -> badCredClient.get("myCacheKey"));
-
-    // Bad Auth for Set
     assertThrows(
-        PermissionDeniedException.class,
-        () ->
-            badCredClient.set(
-                "myCacheKey",
-                ByteBuffer.wrap("cache me if you can".getBytes(StandardCharsets.UTF_8)),
-                500));
+        PermissionDeniedException.class, () -> getCache("BAD_TOKEN", "dummy", Optional.empty()));
   }
 
   @Test
   public void unreachableEndpoint_ThrowsException() {
-    Cache cache =
-        new Cache(
-            System.getenv("TEST_AUTH_TOKEN"),
-            System.getenv("TEST_CACHE_NAME"),
-            "nonexistent.preprod.a.momentohq.com");
-
-    assertThrows(ClientSdkException.class, () -> cache.get("key"));
+    assertThrows(
+        ClientSdkException.class,
+        () ->
+            new Cache(
+                System.getenv("TEST_AUTH_TOKEN"),
+                System.getenv("TEST_CACHE_NAME"),
+                "nonexistent.preprod.a.momentohq.com"));
   }
 
-  @Disabled("TODO: Update to catch cache not ready and then do a get again to see not found.")
   @Test
   public void invalidCache_ThrowsNotFoundException() {
-    Cache cache =
-        getCache(System.getenv("TEST_AUTH_TOKEN"), UUID.randomUUID().toString(), Optional.empty());
-
-    assertThrows(CacheNotFoundException.class, () -> cache.get("key"));
+    assertThrows(
+        CacheNotFoundException.class,
+        () ->
+            getCache(
+                System.getenv("TEST_AUTH_TOKEN"), UUID.randomUUID().toString(), Optional.empty()));
   }
 
   @Test

diff --git a/momento-sdk/src/main/java/momento/sdk/Cache.java b/momento-sdk/src/main/java/momento/sdk/Cache.java
@@ -14,6 +14,8 @@
 import grpc.cache_client.SetResponse;
 import io.grpc.ClientInterceptor;
 import io.grpc.ManagedChannel;
+import io.grpc.Status;
+import io.grpc.StatusRuntimeException;
 import io.grpc.netty.GrpcSslContexts;
 import io.grpc.netty.NettyChannelBuilder;
 import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
@@ -47,15 +49,6 @@ public final class Cache implements Closeable {
   private final ManagedChannel channel;
   private final Optional<Tracer> tracer;
 
-  /**
-   * Builds an instance of {@link Cache} used to interact w/ SCS with a default endpoint.
-   *
-   * @param authToken Token to authenticate with Cache Service
-   */
-  public Cache(String authToken, String cacheName) {
-    this(authToken, cacheName, Optional.empty());
-  }
-
   /**
    * Builds an instance of {@link Cache} that will interact with a specified endpoint
    *
@@ -66,14 +59,6 @@ public Cache(String authToken, String cacheName, String endpoint) {
     this(authToken, cacheName, Optional.empty(), endpoint);
   }
 
-  /**
-   * @param authToken Token to authenticate with SCS
-   * @param openTelemetry Open telemetry instance to hook into client traces
-   */
-  public Cache(String authToken, String cacheName, Optional<OpenTelemetry> openTelemetry) {
-    this(authToken, cacheName, openTelemetry, "alpha.cacheservice.com");
-  }
-
   /**
    * Builds an instance of {@link Cache} used to interact w/ SCS
    *
@@ -124,6 +109,35 @@ public Cache(
     this.futureStub = ScsGrpc.newFutureStub(channel);
     this.channel = channel;
     this.tracer = openTelemetry.map(ot -> ot.getTracer("momento-java-scs-client", "1.0.0"));
+    waitTillReady();
+  }
+
+  private void waitTillReady() {
+    long start = System.currentTimeMillis();
+    long maxRetryDurationMillis = 5000;
+    long backoffDurationMillis = 5;
+    StatusRuntimeException lastRetriedException = null;
+
+    while (System.currentTimeMillis() - start < maxRetryDurationMillis) {
+      try {
+        // The key has no special meaning. Just any key string would work.
+        this.blockingStub.get(buildGetRequest(convert("000")));
+        return;
+      } catch (StatusRuntimeException e) {
+        if (e.getStatus().getCode() == Status.Code.UNKNOWN
+            || e.getStatus().getCode() == Status.Code.UNAVAILABLE) {
+          try {
+            Thread.sleep(backoffDurationMillis);
+          } catch (InterruptedException t) {
+            throw CacheServiceExceptionMapper.convert(t);
+          }
+          lastRetriedException = e;
+        } else {
+          throw CacheServiceExceptionMapper.convert(e);
+        }
+      }
+    }
+    throw CacheServiceExceptionMapper.convertUnhandledExceptions(lastRetriedException);
   }
 
   /**

diff --git a/momento-sdk/src/main/java/momento/sdk/exceptions/CacheServiceExceptionMapper.java b/momento-sdk/src/main/java/momento/sdk/exceptions/CacheServiceExceptionMapper.java
@@ -33,19 +33,22 @@ public static SdkException convert(Exception e) {
           return new CacheNotFoundException(grpcException.getMessage());
 
         default:
-          if (isDnsUnreachable(grpcException)) {
-            return new ClientSdkException(
-                String.format(
-                    "Unable to reach request endpoint. Request failed with %s",
-                    grpcException.getMessage()));
-          }
-          return new InternalServerException(INTERNAL_SERVER_ERROR_MESSAGE);
+          return convertUnhandledExceptions(grpcException);
       }
     }
 
     return new ClientSdkException("SDK Failed to process the request", e);
   }
 
+  public static SdkException convertUnhandledExceptions(StatusRuntimeException e) {
+    if (isDnsUnreachable(e)) {
+      return new ClientSdkException(
+          String.format(
+              "Unable to reach request endpoint. Request failed with %s", e.getMessage()));
+    }
+    return new InternalServerException(INTERNAL_SERVER_ERROR_MESSAGE);
+  }
+
   private static boolean isDnsUnreachable(StatusRuntimeException e) {
     return e.getStatus().getCode() == Status.Code.UNAVAILABLE
         && e.getCause() instanceof RuntimeException