e620833c9e
With this changeset, we provide an implementation for a transaction event API. The goal is to support the emission of events with transactions and sub-transactions, allowing a process post events that may be rolled back later due to an error in the entire process. When journaled, a consumer will be able to commit and rollback with the same behavior as the producer. Events are left to full definition by each component. We may require more structure in the future to ensure consistency but we need more use case before making decisions in that direction. Events may be organized by a topic. A topic defines a single stream of messages, that could be associated with a specific component. The topic defines a grouped stream that may be compacted as one. Only the contextual API is implemented here. After using, we will make a determination to see how useful this across the board. Signed-off-by: Stephen J Day <stephen.day@docker.com>
35 lines
1.1 KiB
Go
35 lines
1.1 KiB
Go
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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