private async Task <bool> UpdateKeyAndCheckIsMaster(EtcdNode node)
{
//Update our key to ensure it doens't expire.
//Only do this if it exists
await etcdClient.CompareAndSwapNodeAsync(node.Key, InstanceId, InstanceId, electionTimeoutSec);
//Todo: validate what happens here if the key's ttl has expired due to this node hanging.
// Expect it to throw and crash the node, orchestrata would then restart and node would be bottom of the list for next master.
await Task.Delay(TimeSpan.FromSeconds(electionTimeoutSec - 10));
//Get a sorted list of nodes for the election Key.
//Oldest nodes will be a at the top. They're a good candidate for master as they're the most stable.
var currentStatus = await etcdClient.GetNodeAsync(ElectionKey, false, false, true);
//The first node is the oldest, if this is us - we're the master
if (currentStatus.Node.Nodes.First().Value == InstanceId)
{
return(true);
}
return(false);
}
static async Task DoSample()
{
EtcdClientOpitions options = new EtcdClientOpitions()
{
#if NET45 // TODO: This is optional, having HTTPS setup could make this work in .NET Core as well, but it's not tested for now
Urls = new string[] { "https://etcd0.em", "https://etcd1.em", "https://etcd2.em" },
#else
Urls = new string[] { "http://*****:*****@"client.p12"), // client cerificate
JsonDeserializer = new NewtonsoftJsonDeserializer(),
};
EtcdClient etcdClient = new EtcdClient(options);
string key = "/my/key";
string value;
// query the value of the node using GetNodeValueAsync
try {
value = await etcdClient.GetNodeValueAsync(key);
Console.WriteLine("The value of `{0}` is `{1}`", key, value);
}
catch (EtcdCommonException.KeyNotFound) {
Console.WriteLine("Key `{0}` does not exist", key);
}
// update the value using SetNodeAsync
EtcdResponse resp = await etcdClient.SetNodeAsync(key, "some value");
Console.WriteLine("Key `{0}` is changed, modifiedIndex={1}", key, resp.Node.ModifiedIndex);
// query the node using GetNodeAsync
resp = await etcdClient.GetNodeAsync(key, ignoreKeyNotFoundException : true);
if (resp == null || resp.Node == null)
{
Console.WriteLine("Key `{0}` does not exist", key);
}
else
{
Console.WriteLine("The value of `{0}` is `{1}`", key, resp.Node.Value);
}
//////////////////////////////////////////////////////////
List <Task <EtcdResponse> > tasks = new List <Task <EtcdResponse> >();
key = "/in-order-queue";
// start monitoring the expire event
WatchChanges(etcdClient, key);
// create 5 in-order nodes, TTL = 3 second
for (int i = 0; i < 5; i++)
{
tasks.Add(etcdClient.CreateInOrderNodeAsync(key, i.ToString(), ttl: 3));
}
await Task.WhenAll(tasks);
// list the in-order nodes
resp = await etcdClient.GetNodeAsync(key, false, recursive : true, sorted : true);
if (resp.Node.Nodes != null)
{
foreach (var node in resp.Node.Nodes)
{
Console.WriteLine("`{0}` = {1}", node.Key, node.Value);
}
}
/////////////////////////////////////////////////////////////
key = "/my/cas-test";
value = Guid.NewGuid().ToString();
try {
resp = await etcdClient.CreateNodeAsync(key, value, null, dir : false);
Console.WriteLine("Key `{0}` is created with value {1}", key, value);
}
catch (EtcdCommonException.NodeExist) {
Console.WriteLine("Key `{0}` already exists", key);
}
long prevIndex = 1;
try {
resp = await etcdClient.CompareAndSwapNodeAsync(key, value, "new value");
Console.WriteLine("Key `{0}` is updated to `{1}`", key, resp.Node.Value);
prevIndex = resp.Node.ModifiedIndex;
}
catch (EtcdCommonException.KeyNotFound) {
Console.WriteLine("Key `{0}` does not exists", key);
}
catch (EtcdCommonException.TestFailed) {
Console.WriteLine("Key `{0}` can not be updated because the supplied previous value is incorrect", key);
}
try {
resp = await etcdClient.CompareAndSwapNodeAsync(key, prevIndex, "new value2");
Console.WriteLine("Key `{0}` is updated to `{1}`", key, resp.Node.Value);
}
catch (EtcdCommonException.KeyNotFound) {
Console.WriteLine("Key `{0}` does not exists", key);
}
catch (EtcdCommonException.TestFailed) {
Console.WriteLine("Key `{0}` can not be updated because the supplied previous index is incorrect", key);
}
try {
resp = await etcdClient.CompareAndDeleteNodeAsync(key, prevIndex + 1);
Console.WriteLine("Key `{0}` is deleted", key);
}
catch (EtcdCommonException.KeyNotFound) {
Console.WriteLine("Key `{0}` does not exists", key);
}
catch (EtcdCommonException.TestFailed) {
Console.WriteLine("Key `{0}` can not be deleted because the supplied previous index is incorrect", key);
}
if (prevIndex == 1) // the previous CAS failed
{
try {
resp = await etcdClient.CompareAndDeleteNodeAsync(key, "new value2");
Console.WriteLine("Key `{0}` is deleted", key);
}
catch (EtcdCommonException.KeyNotFound) {
Console.WriteLine("Key `{0}` does not exists", key);
}
catch (EtcdCommonException.TestFailed) {
Console.WriteLine("Key `{0}` can not be deleted because the supplied previous value is incorrect", key);
etcdClient.DeleteNodeAsync(key, ignoreKeyNotFoundException: true).Wait();
}
}
}
