public async Task TestStoreWithDelay()
{
// Simulates the DB on the server:
var innerStore = new InMemoryKeyValueStore();
// Simulates the connection to the server:
var simulatedDelayStore = new MockDelayKeyValueStore(innerStore);
// Handles connection problems to the server:
var exWrapperStore = new ExceptionWrapperKeyValueStore(simulatedDelayStore);
// Represents the local cache in case the server cant be reached:
var outerStore = new InMemoryKeyValueStore().WithFallbackStore(exWrapperStore);
var key1 = "key1";
var value1 = "value1";
var key2 = "key2";
var value2 = "value2";
{
await outerStore.Set(key1, value1);
Assert.Equal(value1, await outerStore.Get(key1, ""));
Assert.Equal(value1, await innerStore.Get(key1, ""));
}
simulatedDelayStore.throwTimeoutError = true;
var simulatedErrorCatched = false;
exWrapperStore.onError = (Exception e) => { simulatedErrorCatched = true; };
{
await outerStore.Set(key2, value2); // This will cause a timeout error in the "delayed" store
Assert.True(simulatedErrorCatched);
Assert.Contains(key2, await outerStore.GetAllKeys()); // In the outer store the value was set
Assert.False(await innerStore.ContainsKey(key2)); // The inner store never got the update
Assert.False(await exWrapperStore.ContainsKey(key2)); // The exc. wrapper returns false if an error is thrown
Assert.Null(await exWrapperStore.GetAllKeys()); // Will throw another error and return null
}
Log.d("innerStore " + innerStore.latestFallbackGetTimingInMs);
Log.d("simulatedDelayStore " + simulatedDelayStore.latestFallbackGetTimingInMs);
Log.d("exWrapperStore " + exWrapperStore.latestFallbackGetTimingInMs);
Log.d("outerStore " + outerStore.latestFallbackGetTimingInMs);
Assert.Equal(0, innerStore.latestFallbackGetTimingInMs);
Assert.NotEqual(0, exWrapperStore.latestFallbackGetTimingInMs);
Assert.NotEqual(0, outerStore.latestFallbackGetTimingInMs);
}
public async Task TestDelayStoreWithExponentialBackoffRetry()
{
// Simulates the DB on the server:
var innerStore = new InMemoryKeyValueStore();
// Simulates the connection to the server:
var simulatedRemoteConnection = new MockDelayKeyValueStore(innerStore);
var requestRetry = new RetryKeyValueStore(simulatedRemoteConnection, maxNrOfRetries: 5);
var outerStore = new InMemoryKeyValueStore().WithFallbackStore(requestRetry);
var key1 = "key1";
var value1 = "value1";
var key2 = "key2";
var value2 = "value2";
var fallback2 = "fallback2";
{
await outerStore.Set(key1, value1);
Assert.Equal(value1, await outerStore.Get(key1, ""));
Assert.Equal(value1, await innerStore.Get(key1, ""));
}
// Now simulate that the remote DB/server never can be reached:
simulatedRemoteConnection.throwTimeoutError = true;
{
var timeoutErrorCounter = 0;
// In the retry listen to any error if the wrapped store:
requestRetry.onError = (e) => {
Assert.IsType <TimeoutException>(e); // thrown by the simulatedRemoteConnection
timeoutErrorCounter++;
};
var delayedSetTask = outerStore.Set(key2, value2);
Assert.Equal(value2, await outerStore.Get(key2, fallback2)); // In the outer store the value was set
Assert.False(await innerStore.ContainsKey(key2)); // The inner store never got the update
// The delayedSetTask was canceled after 5 retries:
await Assert.ThrowsAsync <OperationCanceledException>(async() => await delayedSetTask);
// There will be minimum 5 TimeoutException in the simulatedRemoteConnection:
Assert.True(requestRetry.maxNrOfRetries <= timeoutErrorCounter);
}
}
public async Task ExampleUsage3()
{
// Simulate the DB on the server
var simulatedDb = new InMemoryKeyValueStore();
// Simulate the connection (with a delay) to the server:
var simulatedRemoteConnection = new MockDelayKeyValueStore(simulatedDb);
// The connection to the server is wrapped by a automatic retry for failing requests:
var requestRetry = new RetryKeyValueStore(simulatedRemoteConnection, maxNrOfRetries: 5);
// Any errors in the inner layers like connection errors, DB errors are catched by default:
var errorHandler = new ExceptionWrapperKeyValueStore(requestRetry);
// The outer store is a local in memory cache and the main point of contact:
var outerStore = new InMemoryKeyValueStore().WithFallbackStore(errorHandler);
var key1 = "key1";
var value1 = "value1";
var fallback1 = "fallback1";
await outerStore.Set(key1, value1);
Assert.Equal(value1, await outerStore.Get(key1, fallback1));
Assert.Equal(value1, await simulatedDb.Get(key1, fallback1));
// Simmulate connection problems to the remote DB:
simulatedRemoteConnection.throwTimeoutError = true;
var key2 = "key2";
var value2 = "value2";
var fallback2 = "fallback2";
// Awaiting a set will take some time since there will be 5 retries:
await outerStore.Set(key2, value2);
// The outer store has the set value cached:
Assert.Equal(value2, await outerStore.Get(key2, fallback2));
// But the request never reached the simulated DB:
Assert.False(await simulatedDb.ContainsKey(key2));
}
