diff options
Diffstat (limited to 'entity/dag/operation.go')
| -rw-r--r-- | entity/dag/operation.go | 16 |
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 |