diff options
Diffstat (limited to 'entity/dag/operation.go')
| -rw-r--r-- | entity/dag/operation.go | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/entity/dag/operation.go b/entity/dag/operation.go new file mode 100644 index 00000000..a320859f --- /dev/null +++ b/entity/dag/operation.go @@ -0,0 +1,48 @@ +package dag + +import ( + "github.com/MichaelMure/git-bug/entity" + "github.com/MichaelMure/git-bug/identity" + "github.com/MichaelMure/git-bug/repository" +) + +// Operation is a piece of data defining a change to reflect on the state of an Entity. +// What this Operation or Entity's state looks like is not of the resort of this package as it only deals with the +// 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). + // - 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). + // 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 + // Author returns the author of this operation + Author() identity.Interface +} + +// OperationWithFiles is an extended Operation that has files dependency, stored in git. +type OperationWithFiles interface { + Operation + + // GetFiles return the files needed by this operation + // This implies that the Operation maintain and store internally the references to those files. This is how + // this information is read later, when loading from storage. + // For example, an operation that has a text value referencing some files would maintain a mapping (text ref --> + // hash). + GetFiles() []repository.Hash +} |