/// <summary>
/// Am I Primary?
/// </summary>
/// <param name="info">ElectorInfo</param>
/// <returns>True, if so</returns>
public bool AmIPrimary(ElectorInfo info)
{
bool amI = false;
ConnectionMultiplexer redis;
IDatabase db;
ITransaction trans;
DateTime stamp = DateTime.UtcNow;
ElectorInfo otherInfo;
int expireMS = GetExpirationMilliseconds();
try
{
redis = ConnectionMultiplexer.Connect(this._config.RedisConnectionString());
redis.IncludeDetailInExceptions = true;
db = redis.GetDatabase();
trans = db.CreateTransaction();
var text = db.StringGet(info.ApplicationName);
if (string.IsNullOrWhiteSpace(text))
{
otherInfo = info;
}
else
{
otherInfo = JsonConvert.DeserializeObject <ElectorInfo>(text);
}
if (otherInfo.UniqueInstanceId == info.UniqueInstanceId)
{
UpdateKey(db, info, stamp);
amI = true;
}
else
{
var ts = stamp - otherInfo.LastCallUtc;
var age = ts.TotalMilliseconds;
if (age > expireMS)
{
UpdateKey(db, info, stamp);
amI = true;
}
}
trans.Execute();
}
finally
{
db = null;
trans = null;
redis = null;
}
return(amI);
}
/// <summary>
///
/// </summary>
/// <param name="applicationName"></param>
/// <returns></returns>
public bool ForceElection(string applicationName)
{
ConnectionMultiplexer redis;
IDatabase db;
ITransaction trans;
try
{
redis = ConnectionMultiplexer.Connect(this._config.RedisConnectionString());
redis.IncludeDetailInExceptions = true;
db = redis.GetDatabase();
trans = db.CreateTransaction();
DateTime stamp = DateTime.UtcNow.AddDays(-1);
var info = new ElectorInfo()
{
LastCallUtc = stamp, ApplicationName = applicationName, UniqueInstanceId = NO_INSTANCE
};
UpdateKey(db, info, stamp);
trans.Execute();
}
finally
{
db = null;
trans = null;
redis = null;
}
return(true);
}
private void UpdateKey(IDatabase db, ElectorInfo info, DateTime stamp)
{
info.LastCallUtc = stamp;
var text = JsonConvert.SerializeObject(info);
db.KeyDelete(info.ApplicationName);
db.StringSet(info.ApplicationName, text);
}
public void ConCurr_1()
{
bool amIPrimary = false;
RedisElectorProvider prov = new RedisElectorProvider(redisConfig);
prov.SetExpirationMilliseconds(RedisElectorProvider.Recommended_ExpirationMilliseconds);
DateTime stamp = DateTime.UtcNow;
var agent1 = new ElectorInfo()
{
ApplicationName = ApplicationName,
LastCallUtc = stamp,
UniqueInstanceId = Guid.NewGuid().ToString()
};
amIPrimary = prov.AmIPrimary(agent1);
Assert.IsTrue(amIPrimary, "Agent 1");
var agent2 = new ElectorInfo()
{
ApplicationName = ApplicationName,
LastCallUtc = stamp,
UniqueInstanceId = Guid.NewGuid().ToString()
};
amIPrimary = prov.AmIPrimary(agent2);
Assert.IsFalse(amIPrimary, "Agent 2");
Thread.Sleep(RedisElectorProvider.Recommended_ExpirationMilliseconds + 1000);
agent2.LastCallUtc = DateTime.UtcNow;
amIPrimary = prov.AmIPrimary(agent2);
Assert.IsTrue(amIPrimary, "Agent 2");
agent1.UpdateLastCallUtc();
amIPrimary = prov.AmIPrimary(agent1);
Assert.IsFalse(amIPrimary, "Agent 1");
amIPrimary = prov.AmIPrimary(agent1);
Assert.IsFalse(amIPrimary, "Agent 1");
amIPrimary = prov.AmIPrimary(agent2);
Assert.IsTrue(amIPrimary, "Agent 2");
}
static int Main(string[] args)
{
AppDomain.CurrentDomain.UnhandledException += CurrentDomain_UnhandledException;
logger = LogFactoryHelper.CreateLogger <Program>();
string fallbackFilename = @"VCAP_Services.json";
if (args.Length > 0)
{
fallbackFilename = args[0];
}
// Get Assembly Object, casting it to this class type
var assembly = typeof(Program).Assembly;
// Get all custom attribute data
foreach (var attribute in assembly.GetCustomAttributesData())
{
// try to find a value
if (!attribute.TryParse(out string value))
{
value = string.Empty;
}
// write name and value
if (!string.IsNullOrWhiteSpace(value))
{
logger.LogInformation($"{attribute.AttributeType.Name} - {value}");
}
}
var whoIAm = new ElectorInfo()
{
ApplicationName = "Demo_RedisElector_Singleton", LastCallUtc = DateTime.UtcNow, UniqueInstanceId = Guid.NewGuid().ToString()
};
logger.LogInformation("I Am: {0}", whoIAm.ToString());
var redisConfig = GetConfig("p-redis", fallbackFilename);
var prov = new RedisElectorProvider(redisConfig);
prov.SetExpirationMilliseconds(RedisElectorProvider.Recommended_ExpirationMilliseconds);
while (shouldRun)
{
if (prov.AmIPrimary(whoIAm))
{
if (dice.Next(1, 100) > 70)
{
int waiter = RedisElectorProvider.Recommended_ExpirationMilliseconds * 2;
logger.LogWarning("{0} for {1} ms, Primary Faulting", whoIAm.UniqueInstanceId, waiter);
prov.ForceElection(whoIAm.ApplicationName);
Thread.Sleep(waiter);
}
else
{
// Fake: Unit of Work
int waiter = dice.Next(RedisElectorProvider.Minimim_ExpirationMilliseconds, RedisElectorProvider.Recommended_ExpirationMilliseconds * 2);
logger.LogInformation("{0} for {1} ms, Primary Working", whoIAm.UniqueInstanceId, waiter);
Thread.Sleep(waiter);
}
}
else
{
int waiter = RedisElectorProvider.Minimim_ExpirationMilliseconds;
logger.LogInformation("{0} for {1} ms, Not Primary", whoIAm.UniqueInstanceId, waiter);
Thread.Sleep(waiter);
}
}
Environment.ExitCode = exitCode;
return(exitCode);
}
