Class EventBus
One endpoint on an event bus.
public sealed class EventBus : IDisposable- Inheritance
-
EventBus
- Implements
- Inherited Members
Remarks
One publisher, many subscribers, inside a single process. It is how the parts of a gateway talk to each other without knowing about each other, so a sampler can announce a reading and whatever cares about readings picks it up.
An endpoint both publishes and receives, and it receives what it publishes itself. It only sees events published after it existed, so subscribe before publishing anything it needs to see. Only NextAsync() and NextTextAsync() wait: publishing and subscribing return at once, even while a wait on the same endpoint is open.
Constructors
EventBus(int)
Creates an event bus.
public EventBus(int capacity = 64)Parameters
capacityintHow many events a slow subscriber may fall behind before it starts missing them, rounded up to the next power of two and at most 1048576.
Exceptions
- ArgumentOutOfRangeException
The capacity is negative.
- PamojaException
The native bus could not be created.
Properties
Missed
How many events this endpoint lost by falling behind, as of its last completed wait.
public long Missed { get; }Property Value
Methods
Dispose()
Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
public void Dispose()NextAsync()
Waits for the next event on this endpoint.
public Task<byte[]> NextAsync()Returns
Remarks
The wait lasts until an event arrives, and it holds a thread-pool thread while it does. NextAsync(TimeSpan) gives up sooner.
Exceptions
- PamojaException
The native call failed.
NextAsync(TimeSpan)
Waits a limited time for the next event on this endpoint.
public Task<byte[]> NextAsync(TimeSpan timeout)Parameters
timeoutTimeSpanHow long to wait, rounded up to the next millisecond.
Returns
Remarks
A wait that runs out takes no event, so the next one is left for the next call.
Exceptions
- ArgumentOutOfRangeException
The time limit is negative.
- TimeoutException
No event arrived in time.
- PamojaException
The native call failed.
NextTextAsync()
Waits for the next event on this endpoint, as text.
public Task<string> NextTextAsync()Returns
Exceptions
- PamojaException
The native call failed.
NextTextAsync(TimeSpan)
Waits a limited time for the next event on this endpoint, as text.
public Task<string> NextTextAsync(TimeSpan timeout)Parameters
timeoutTimeSpanHow long to wait, rounded up to the next millisecond.
Returns
Exceptions
- ArgumentOutOfRangeException
The time limit is negative.
- TimeoutException
No event arrived in time.
- PamojaException
The native call failed.
Publish(ReadOnlyMemory<byte>)
Publishes an event to every subscriber, this endpoint included.
public void Publish(ReadOnlyMemory<byte> payload)Parameters
payloadReadOnlyMemory<byte>The event bytes.
Remarks
It never waits: a subscriber that has fallen behind loses its oldest event rather than holding up the publisher.
Exceptions
- PamojaException
The native call failed.
Publish(string)
Publishes text to every subscriber, this endpoint included: an event name, or a reading written out.
public void Publish(string text)Parameters
textstringThe event text, as UTF-8.
Remarks
It never waits: a subscriber that has fallen behind loses its oldest event rather than holding up the publisher.
Exceptions
- PamojaException
The native call failed.
Publisher()
Takes a publish-only handle on the same bus, for a part that announces and never reads.
public EventPublisher Publisher()Returns
- EventPublisher
The publisher.
Exceptions
- PamojaException
The native call failed.
Subscribe()
Takes another endpoint on the same bus.
public EventBus Subscribe()Returns
- EventBus
An endpoint that sees events published from now on.
Exceptions
- PamojaException
The native call failed.