36 lines
1.1 KiB
Go
36 lines
1.1 KiB
Go
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package events
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import "context"
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type topicKey struct{}
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// WithTopic returns a context with a new topic set, such that events emmited
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// from the resulting context will be marked with the topic.
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//
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// A topic groups events by the target module they operate on. This is
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// primarily designed to support multi-module log compaction of events. In
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// typical journaling systems, the entries operate on a single data structure.
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// When compacting the journal, we can replace all former log entries with a
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// summary data structure that will result in the same state.
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//
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// By providing a compaction mechansim by topic, we can prune down to a data
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// structure oriented towards a single topic, leaving unrelated messages alone.
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func WithTopic(ctx context.Context, topic string) context.Context {
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return context.WithValue(ctx, topicKey{}, topic)
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}
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func getTopic(ctx context.Context) string {
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topic := ctx.Value(topicKey{})
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if topic == nil {
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return ""
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}
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return topic.(string)
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}
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// RegisterCompactor sets the compacter for the given topic.
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func RegisterCompactor(topic string, compactor interface{}) {
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panic("not implemented")
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}
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