public void DefaultBulkheadSizeIs10()
{
// This is mainly to ensure we don't introduce a breaking change for clients
// who rely on the default configs.
var key = GroupKey.Named(Rand.String());
var context = new CommandContextImpl();
var bulkhead = context.GetBulkhead(key);
Assert.Equal(10, bulkhead.CountAvailable);
}
public void ReturnsSameBulkheadForKey()
{
// Bulkheads are long-lived objects and used for many requests. In the absence
// of any configuration changes, we should be using the same one through the
// lifetime of the app.
var key = GroupKey.Named(Rand.String());
var context = new CommandContextImpl();
var bulkhead = context.GetBulkhead(key);
Assert.Equal(bulkhead, context.GetBulkhead(key));
}
public void IgnoresConfigChangeToInvalidValues()
{
var key = Rand.String();
var groupKey = GroupKey.Named(key);
var configKey = "mjolnir.bulkhead." + key + ".maxConcurrent";
var context = new CommandContextImpl();
// Should have a valid default value initially.
Assert.Equal(10, context.GetBulkhead(groupKey).CountAvailable);
// Negative limits aren't valid.
ConfigProvider.Instance.Set(configKey, -1);
Assert.Equal(10, context.GetBulkhead(groupKey).CountAvailable);
// Zero (disallow all) is a valid value.
ConfigProvider.Instance.Set(configKey, 0);
Assert.Equal(0, context.GetBulkhead(groupKey).CountAvailable);
}
public void ReturnsNewBulkheadWhenConfigChanges()
{
// Config can be used to resize the bulkhead at runtime, which results in a new
// bulkhead being created.
// To ensure consistency, callers who retrieve a bulkhead and call TryEnter()
// on it should keep a local reference to the same bulkhead to later call
// Release() on (rather than re-retrieving the bulkhead from the context).
// That behavior is tested elsewhere (with the BulkheadInvoker tests).
var key = Rand.String();
var groupKey = GroupKey.Named(key);
var configKey = "mjolnir.bulkhead." + key + ".maxConcurrent";
var context = new CommandContextImpl();
int initialExpectedCount = 5;
ConfigProvider.Instance.Set(configKey, initialExpectedCount);
var bulkhead = context.GetBulkhead(groupKey);
Assert.Equal(5, initialExpectedCount);
// Now, change the config value and make sure it gets applied.
int newExpectedCount = 2;
ConfigProvider.Instance.Set(configKey, newExpectedCount);
// Shouldn't change any existing referenced bulkheads...
Assert.Equal(initialExpectedCount, bulkhead.CountAvailable);
// ...but newly-retrieved bulkheads should get a new instance
// with the updated count.
var newBulkhead = context.GetBulkhead(groupKey);
Assert.NotEqual(bulkhead, newBulkhead);
Assert.Equal(newExpectedCount, newBulkhead.CountAvailable);
}