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-rw-r--r--entity/dag/operation.go16
1 files changed, 13 insertions, 3 deletions
diff --git a/entity/dag/operation.go b/entity/dag/operation.go
index b0a78de6..94974a82 100644
--- a/entity/dag/operation.go
+++ b/entity/dag/operation.go
@@ -10,13 +10,23 @@ import (
// data structure and storage.
type Operation interface {
// Id return the Operation identifier
+ //
// Some care need to be taken to define a correct Id derivation and enough entropy in the data used to avoid
// collisions. Notably:
- // - the Id of the first Operation will be used as the Id of the Entity. Collision need to be avoided across entities of the same type
- // (example: no collision within the "bug" namespace).
+ // - the Id of the first Operation will be used as the Id of the Entity. Collision need to be avoided across entities
+ // of the same type (example: no collision within the "bug" namespace).
// - collisions can also happen within the set of Operations of an Entity. Simple Operation might not have enough
// entropy to yield unique Ids (example: two "close" operation within the same second, same author).
- // A common way to derive an Id will be to use the DeriveId function on the serialized operation data.
+ // If this is a concern, it is recommended to include a piece of random data in the operation's data, to guarantee
+ // a minimal amount of entropy and avoid collision.
+ //
+ // Author's note: I tried to find a clever way around that inelegance (stuffing random useless data into the stored
+ // structure is not exactly elegant) but I failed to find a proper way. Essentially, anything that would reuse some
+ // other data (parent operation's Id, lamport clock) or the graph structure (depth) impose that the Id would only
+ // make sense in the context of the graph and yield some deep coupling between Entity and Operation. This in turn
+ // make the whole thing even less elegant.
+ //
+ // A common way to derive an Id will be to use the entity.DeriveId() function on the serialized operation data.
Id() entity.Id
// Validate check if the Operation data is valid
Validate() error