@0xb021b19fd5986342;

using Common = import "common.capnp";
using Stream = import "stream.capnp";

interface Trace {
    watch @0 (request :WatchRequest, receiver :Stream.Receiver(TraceEvent)) -> (stream :Stream.Sender);
}

struct WatchRequest {
    # Start watching trace events with the provided filter

    filter @0 :Text;
    # Filters which trace events should be streamed
}

struct TraceEvent {
    union {
        registerThread @0 :RegisterThreads;
        # A new thread was registered

        registerMetadata @1 :Common.RegisterMetadata;
        # A new span metadata was registered

        newSpan @2 :Common.Span;
        # A span was created

        enterSpan @3 :Enter;
        # A span was entered

        exitSpan @4 :Exit;
        # A span was exited

        closeSpan @5 :Close;
        # A span was closed
    }

    struct RegisterThreads {
        # Signals that a new thread was registered

        names @0 :Common.IntMap(Text);
        # Maps the registered thread id's to their associated name
    }

    struct Enter {
        # Signals that a span was entered

        spanId @0 :Common.SpanId;
        # Identified the span that was entered

        threadId @1 :UInt64;
        # Identifies who entered the span

        at @2 :Common.Timestamp;
        # Identifies when the span was entered
    }

    struct Exit {
        # Signals that a span was exited
        
        spanId @0 :Common.SpanId;
        # Identifies the spawn that was exited

        threadId @1 :UInt64;
        # Identifies who exited the span

        at @2 :Common.Timestamp;
        # Identifies when the span was exited
    }

    struct Close {
        # Signals that a span was closed

        spanId @0 :Common.SpanId;
        # Identifies the span that was closed

        at @1 :Common.Timestamp;
        # Identifies when the span was closed
    }
}