/// <summary>
/// <para>
/// <b>INTERNAL USE ONLY:</b> Returns a <see cref="HiveBus"/> connected to the hive
/// <b>neon</b> virtual host. This property is intended for use only by neonHIVE
/// tools, services and containers.
/// </para>
/// <note>
/// <b>WARNING:</b> The <see cref="HiveBus"/> instance returned should <b>NEVER BE DISPOSED</b>.
/// </note>
/// </summary>
/// <param name="useBootstrap">
/// Optionally specifies that the settings returned should directly
/// reference to the HiveMQ cluster nodes rather than routing traffic
/// through the <b>private</b> traffic manager. This is used internally
/// to resolve chicken-and-the-egg dilemmas for the traffic manager and
/// proxy implementations that rely on HiveMQ messaging.
/// </param>
public HiveBus NeonHiveBus(bool useBootstrap = false)
{
var bus = neonHiveBus;
if (bus != null)
{
return(bus);
}
lock (syncLock)
{
if (neonHiveBus != null)
{
return(neonHiveBus);
}
if (!useBootstrap)
{
return(neonHiveBus = parent.GetNeonSettings(useBootstrap: false).ConnectHiveBus());
}
// Remember the bootstrap settings and then start a task that
// periodically polls Consul for settings changes to raise the
// [HiveMQBootstrapChanged] event when changes happen.
bootstrapSettings = parent.GetNeonSettings(useBootstrap);
neonHiveBus = bootstrapSettings.ConnectHiveBus();
bootstrapChangeDetector = Task.Run(() => BootstrapChangeDetector());
return(neonHiveBus);
}
}
/// <summary>
/// Polls Consul for changes to the <b>neon</b> virtual host HiveMQ
/// bootstrap settings and raises the <see cref="HiveMQBootstrapChanged"/>
/// when this happens.
/// </summary>
/// <returns>The tracking <see cref="Task"/>.</returns>
private async Task BootstrapChangeDetector()
{
var pollInterval = TimeSpan.FromSeconds(120);
// Delay for a random period of time between [0..pollInterval]. This
// will help prevent Consul traffic spikes when services are started
// at the same time.
await Task.Delay(NeonHelper.RandTimespan(pollInterval));
// This will spin forever once started when a NeonHiveBus using bootstrap
// settings is created above. This polls Consul for changes to the [neon]
// HiveMQ virtual host settings stored in Consul. We'll be performing two
// Consul lookups for each poll (one to get the [neon] vhost settings and
// the other to obtain the bootstrap settings.
//
// When a settings change is detected, we'll first ensure that we've
// establisted a new [neonHiveBus] connection using the new settings and
// then we'll raise the change event.
while (true)
{
try
{
var latestBootstrapSettngs = parent.GetNeonSettings(useBootstrap: true);
if (!NeonHelper.JsonEquals(bootstrapSettings, latestBootstrapSettngs))
{
// The latest bootstrap settings don't match what we used to
// connect the current [bus].
lock (syncLock)
{
bootstrapSettings = latestBootstrapSettngs;
neonHiveBus = bootstrapSettings.ConnectHiveBus();
}
var handler = bootstrapChangedEvent;
handler?.Invoke(this, latestBootstrapSettngs);
}
}
catch (Exception e)
{
log.LogError(e);
}
await Task.Delay(pollInterval);
}
}