Making cartservice more reliable

1. Making sure we re-create redis connection upon disconnect
2. Fixed local cart store implementation to handle updates (useful for testing w/o redis)
3. Fixed windows scripts to work against redis correctly

.gitignore

@@ -4,3 +4,5 @@ pkg/
 *.pyc
 *.swp
 *~
+.vs/slnx.sqlite
+.vs/microservices-demo/v15/.suo

src/cartservice/Program.cs

@@ -33,26 +33,36 @@ namespace cartservice
         {
             // Run the server in a separate thread and make the main thread busy waiting.
             // The busy wait is because when we run in a container, we can't use techniques such as waiting on user input (Console.Readline())
-            Task.Run(async () =>
+            Task serverTask = Task.Run(async () =>
             {
-                Console.WriteLine($"Trying to start a grpc server at  {host}:{port}");
+                try
-                Server server = new Server
                 {
-                    Services = { Hipstershop.CartService.BindService(new CartServiceImpl(cartStore)) },
+                    Console.WriteLine($"Trying to start a grpc server at  {host}:{port}");
-                    Ports = { new ServerPort(host, port, ServerCredentials.Insecure) }
+                    Server server = new Server
-                };
+                    {
+                        Services = { Hipstershop.CartService.BindService(new CartServiceImpl(cartStore)) },
+                        Ports = { new ServerPort(host, port, ServerCredentials.Insecure) }
+                    };
 
-                Console.WriteLine($"Cart server is listening at {host}:{port}");
+                    Console.WriteLine($"Cart server is listening at {host}:{port}");
-                server.Start();
+                    server.Start();
 
-                await cartStore.InitializeAsync();
+                    await cartStore.InitializeAsync();
+                    Console.WriteLine("Initialization completed");
+
+                    // Keep the server up and running
+                    while(true)
+                    {
+                        Thread.Sleep(TimeSpan.FromMinutes(10));
+                    }
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine(ex);
+                }
             });
 
-            // Busy wait to keep the process alive
+            return Task.WaitAny(new[] { serverTask });
-            while(true)
-            {
-                Thread.Sleep(TimeSpan.FromMinutes(10));
-            }
         }
 
         static void Main(string[] args)
@@ -69,6 +79,8 @@ namespace cartservice
                     Parser.Default.ParseArguments<ServerOptions>(args).MapResult(
                         (ServerOptions options) => 
                         {
+                            Console.WriteLine($"Started as process with id {System.Diagnostics.Process.GetCurrentProcess().Id}");
+
                             // Set hostname/ip address
                             string hostname = options.Host;
                             if (string.IsNullOrEmpty(hostname))
@@ -106,7 +118,10 @@ namespace cartservice
                             // Redis was specified via command line or environment variable
                             if (!string.IsNullOrEmpty(redis))
                             {
+                                // If you want to start cart store using local cache in process, you can replace the following line with this:
+                                // cartStore = new LocalCartStore();
                                 cartStore = new RedisCartStore(redis);
+
                                 return StartServer(hostname, port, cartStore);
                             }
                             else

src/cartservice/cartstore/LocalCartStore.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Threading.Tasks;
+using System.Linq;
 using cartservice.interfaces;
 using Hipstershop;
 
@@ -10,6 +11,7 @@ namespace cartservice.cartstore
     {
         // Maps between user and their cart
         private ConcurrentDictionary<string, Hipstershop.Cart> userCartItems = new ConcurrentDictionary<string, Hipstershop.Cart>();
+        private readonly Hipstershop.Cart emptyCart = new Hipstershop.Cart();
 
         public Task InitializeAsync()
         {
@@ -29,8 +31,17 @@ namespace cartservice.cartstore
             userCartItems.AddOrUpdate(userId, newCart,
             (k, exVal) =>
             {
-                // Currently we assume that we only add to the cart
+                // If the item exists, we update its quantity
-                exVal.Items.Add(new Hipstershop.CartItem { ProductId = productId, Quantity = quantity });
+                var existingItem = exVal.Items.SingleOrDefault(item => item.ProductId == productId);
+                if (existingItem != null)
+                {
+                    existingItem.Quantity += quantity;
+                }
+                else
+                {
+                    exVal.Items.Add(new Hipstershop.CartItem { ProductId = productId, Quantity = quantity });
+                }
+
                 return exVal;
             });
 
@@ -40,7 +51,7 @@ namespace cartservice.cartstore
         public Task EmptyCartAsync(string userId)
         {
             Console.WriteLine($"EmptyCartAsync called with userId={userId}");
-            userCartItems[userId] = new Hipstershop.Cart();
+            userCartItems[userId] = emptyCart;
 
             return Task.CompletedTask;
         }
@@ -52,7 +63,9 @@ namespace cartservice.cartstore
             if (!userCartItems.TryGetValue(userId, out cart))
             {
                 Console.WriteLine($"No carts for user {userId}");
+                return Task.FromResult(emptyCart);
             }
+
             return Task.FromResult(cart);
         }
     }

src/cartservice/cartstore/RedisCartStore.cs

@@ -1,9 +1,11 @@
 using System;
 using System.IO;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using cartservice.interfaces;
 using Google.Protobuf;
+using Grpc.Core;
 using Hipstershop;
 using StackExchange.Redis;
 
@@ -12,137 +14,174 @@ namespace cartservice.cartstore
     public class RedisCartStore : ICartStore
     {
         private const string CART_FIELD_NAME = "cart";
+        private const int REDIS_RETRY_NUM = 5;
 
-        private static ConnectionMultiplexer redis;
+        private volatile ConnectionMultiplexer redis;
+        private volatile bool isRedisConnectionOpened = false;
 
+        private readonly object locker = new object();
         private readonly byte[] emptyCartBytes;
-<<<<<<< HEAD
         private readonly string connectionString;
-        private readonly string redisAddr;
+
-||||||| merged common ancestors
+        private readonly ConfigurationOptions redisConnectionOptions;
-=======
-        private readonly string connectionString;
->>>>>>> origin
 
         public RedisCartStore(string redisAddress)
         {
             // Serialize empty cart into byte array.
             var cart = new Hipstershop.Cart();
             emptyCartBytes = cart.ToByteArray();
-            this.redisAddr = redisAddress;
             connectionString = $"{redisAddress},ssl=false,allowAdmin=true,connectRetry=5";
-            Console.WriteLine($"Going to use Redis cache at this address: {connectionString}");
+            
+            redisConnectionOptions = ConfigurationOptions.Parse(connectionString);
+
+            // Try to reconnect if first retry failed (up to 5 times with exponential backoff)
+            redisConnectionOptions.ConnectRetry = REDIS_RETRY_NUM;
+            redisConnectionOptions.ReconnectRetryPolicy = new ExponentialRetry(100);
+            
+            redisConnectionOptions.KeepAlive = 180;
         }
 
-<<<<<<< HEAD
         public Task InitializeAsync()
         {
-||||||| merged common ancestors
+            EnsureRedisConnected();
-            string connectionString = $"{redisAddress},ssl=false,allowAdmin=true";
+            return Task.CompletedTask;
-=======
-            connectionString = $"{redisAddress},ssl=false,allowAdmin=true";
-            Console.WriteLine($"Going to use Redis cache at this address: {connectionString}");
         }
 
-        public async Task InitializeAsync()
+        private void EnsureRedisConnected()
         {
->>>>>>> origin
+            if (isRedisConnectionOpened)
-            Console.WriteLine("Connecting to Redis: " + connectionString);
+            {
-<<<<<<< HEAD
+                return;
+            }
 
-            redis = ConnectionMultiplexer.Connect(connectionString);
+            // Connection is closed or failed - open a new one but only at the first thread
-            Console.WriteLine("Connected successfully to Redis");
+            lock (locker)
+            {
+                if (isRedisConnectionOpened)
+                {
+                    return;
+                }
 
-            return Task.CompletedTask;
+                Console.WriteLine("Connecting to Redis: " + connectionString);
-||||||| merged common ancestors
+                redis = ConnectionMultiplexer.Connect(redisConnectionOptions);
-            redis = ConnectionMultiplexer.Connect(connectionString);
+                
-=======
+                if (redis == null || !redis.IsConnected)
-            redis = await ConnectionMultiplexer.ConnectAsync(connectionString, Console.Out);
+                {
-            Console.WriteLine("Connected successfully to Redis");
+                    Console.WriteLine("Wasn't able to connect to redis");
->>>>>>> origin
+                    
+                    // We weren't able to connect to redis despite 5 retries with exponential backoff
+                    throw new ApplicationException("Wasn't able to connect to redis");
+                }
+
+                Console.WriteLine("Successfully connected to Redis");
+                var cache = redis.GetDatabase();
+
+                Console.WriteLine("Performing small test");
+                cache.StringSet("cart", "OK" );
+                object res = cache.StringGet("cart");
+                Console.WriteLine($"Small test result: {res}");
+
+                redis.InternalError += (o, e) => { Console.WriteLine(e.Exception); };
+                redis.ConnectionRestored += (o, e) => 
+                {
+                    isRedisConnectionOpened = true;
+                    Console.WriteLine("Connection to redis was retored successfully"); 
+                };
+                redis.ConnectionFailed += (o, e) => 
+                {
+                    Console.WriteLine("Connection failed. Disposing the object"); 
+                    isRedisConnectionOpened = false;
+                };
+
+                isRedisConnectionOpened = true;
+            }
         }
 
         public async Task AddItemAsync(string userId, string productId, int quantity)
         {
             Console.WriteLine($"AddItemAsync called with userId={userId}, productId={productId}, quantity={quantity}");
 
-            var db = redis.GetDatabase();
+            try
-            
+            {
-            // Access the cart from the cache
+                EnsureRedisConnected();
-            var value = await db.HashGetAsync(userId, CART_FIELD_NAME);
+                
+                var db = redis.GetDatabase();
+                
+                // Access the cart from the cache
+                var value = await db.HashGetAsync(userId, CART_FIELD_NAME);
 
-            Hipstershop.Cart cart;
+                Hipstershop.Cart cart;
-            if (value.IsNull)
+                if (value.IsNull)
-            {
-                cart = new Hipstershop.Cart();
-                cart.UserId = userId;
-                cart.Items.Add(new Hipstershop.CartItem { ProductId = productId, Quantity = quantity });
-            }
-            else
-            {
-                cart = Hipstershop.Cart.Parser.ParseFrom(value);
-                var existingItem = cart.Items.SingleOrDefault(i => i.ProductId == productId);
-                if (existingItem == null)
                 {
+                    cart = new Hipstershop.Cart();
+                    cart.UserId = userId;
                     cart.Items.Add(new Hipstershop.CartItem { ProductId = productId, Quantity = quantity });
                 }
                 else
                 {
-                    existingItem.Quantity += quantity;
+                    cart = Hipstershop.Cart.Parser.ParseFrom(value);
+                    var existingItem = cart.Items.SingleOrDefault(i => i.ProductId == productId);
+                    if (existingItem == null)
+                    {
+                        cart.Items.Add(new Hipstershop.CartItem { ProductId = productId, Quantity = quantity });
+                    }
+                    else
+                    {
+                        existingItem.Quantity += quantity;
+                    }
                 }
-            }
 
-            await db.HashSetAsync(userId, new[]{ new HashEntry(CART_FIELD_NAME, cart.ToByteArray()) });
+                await db.HashSetAsync(userId, new[]{ new HashEntry(CART_FIELD_NAME, cart.ToByteArray()) });
+            }
+            catch (Exception ex)
+            {
+                throw new RpcException(new Status(StatusCode.FailedPrecondition, $"Can't access cart storage. {ex}"));
+            }
         }
 
         public async Task EmptyCartAsync(string userId)
         {
             Console.WriteLine($"EmptyCartAsync called with userId={userId}");
 
-            var db = redis.GetDatabase();
+            try
+            {
+                EnsureRedisConnected();
+                var db = redis.GetDatabase();
 
-            // Update the cache with empty cart for given user
+                // Update the cache with empty cart for given user
-            await db.HashSetAsync(userId, new[] { new HashEntry(CART_FIELD_NAME, emptyCartBytes) });
+                await db.HashSetAsync(userId, new[] { new HashEntry(CART_FIELD_NAME, emptyCartBytes) });
+            }
+            catch (Exception ex)
+            {
+                throw new RpcException(new Status(StatusCode.FailedPrecondition, $"Can't access cart storage. {ex}"));
+            }
         }
 
         public async Task<Hipstershop.Cart> GetCartAsync(string userId)
         {
             Console.WriteLine($"GetCartAsync called with userId={userId}");
-<<<<<<< HEAD
-            try
-            {
-                var db = redis.GetDatabase();
-                // Access the cart from the cache
-||||||| merged common ancestors
-            var db = redis.GetDatabase();
-=======
-            try
-            {
-                var db = redis.GetDatabase();
->>>>>>> origin
 
-<<<<<<< HEAD
+            try
-                var value = await db.HashGetAsync(userId, CART_FIELD_NAME);
+            {
-||||||| merged common ancestors
+                EnsureRedisConnected();
-            // Access the cart from the cache
+
-            var value = await db.HashGetAsync(userId, CART_FIELD_NAME);
+                var db = redis.GetDatabase();
-=======
+
                 // Access the cart from the cache
                 var value = await db.HashGetAsync(userId, CART_FIELD_NAME);
->>>>>>> origin
 
                 if (!value.IsNull)
                 {
                     return Hipstershop.Cart.Parser.ParseFrom(value);
                 }
-            }
-            catch (Exception e)
-            {
-                Console.WriteLine(e);
-            }
 
-            // We decided to return empty cart in cases when user wasn't in the cache before
+                // We decided to return empty cart in cases when user wasn't in the cache before
-            return new Hipstershop.Cart();
+                return new Hipstershop.Cart();
+            }
+            catch (Exception ex)
+            {
+                throw new RpcException(new Status(StatusCode.FailedPrecondition, $"Can't access cart storage. {ex}"));
+            }
         }
     }
 }

src/cartservice/scripts/docker_setup.bat

@@ -9,12 +9,13 @@ GOTO End1
 :local
   set REDIS_PORT=6379
   set REDIS_ADDR=localhost:%REDIS_PORT%
-  set LISTEN_ADDR=0.0.0.0
+  set LISTEN_ADDR=localhost
   set PORT=7070
+  set GRPC_TRACE=all
 
   echo running redis emulator locally on a separate window
   taskkill /f /im "redis-server.exe"
-  start redis-server
+  start redis-server "C:\ProgramData\chocolatey\lib\redis-64\redis.windows.conf"
 
   echo running the cart service locally
   dotnet build ..\.
@@ -23,19 +24,24 @@ GOTO End1
 
 :docker_local
   set REDIS_PORT=6379
-  set REDIS_ADDR=redis:%REDIS_PORT%
+  rem set REDIS_ADDR=redis:%REDIS_PORT%
-  set LISTEN_ADDR=0.0.0.0
+  set LISTEN_ADDR=localhost
   set PORT=7070
 
   echo run docker container with redis
-  docker rm --force redis
+  
-  start "" docker run -d --name=redis -p %REDIS_PORT%:%REDIS_PORT% redis
+  echo Forcing to remove redis cache so we always start the container from scratch
-
+  docker rm --force redis > nul 2>&1
+  echo Starting out redis container
+  docker run -d --name=redis redis > nul 2>&1
+  rem This assigns the output of ip4 addr of redis container into REDIS_ADDR
+  FOR /F "tokens=*" %%g IN ('docker inspect -f "{{ .NetworkSettings.Networks.bridge.IPAddress }}" redis') do (SET REDIS_ADDR=%%g)
+  echo addr=%REDIS_ADDR%
   echo building container image for cart service
   docker build -t cartservice ..\.
 
   echo run container image for cart service
-  docker run -it --rm -e REDIS_ADDR=%REDIS_ADDR% -e LISTEN_ADDR=%LISTEN_ADDR% -e PORT=%PORT% -p %PORT%:%PORT% cartservice
+  docker run -it --name=cartservice --rm -e REDIS_ADDR=%REDIS_ADDR%:%REDIS_PORT% -e LISTEN_ADDR=%LISTEN_ADDR% -e PORT=%PORT% -p %PORT%:%PORT% cartservice
 
 GOTO End1
 

tests/cartservice/CartServiceTests.cs

@@ -29,15 +29,16 @@ namespace cartservice
             {
                 UserId = userId,
             };
+
             var cart = await client.GetCartAsync(request);
             Assert.NotNull(cart);
-            
+
             // All grpc objects implement IEquitable, so we can compare equality with by-value semantics
             Assert.Equal(new Cart(), cart);
         }
 
         [Fact]
-        public async Task AddItem_ItemExists_Udpated()
+        public async Task AddItem_ItemExists_Updated()
         {
             string userId = Guid.NewGuid().ToString();