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Diffstat (limited to 'common/src/leap/soledad/common/README.txt')
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diff --git a/common/src/leap/soledad/common/README.txt b/common/src/leap/soledad/common/README.txt new file mode 100644 index 00000000..106efb5e --- /dev/null +++ b/common/src/leap/soledad/common/README.txt @@ -0,0 +1,79 @@ +Soledad common package +====================== + +This package contains Soledad bits used by both server and client. + +Couch U1DB Backend +------------------ + +U1DB backends rely on some atomic operations that modify documents contents +and metadata (conflicts, transaction ids and indexes). The only atomic +operation in Couch is a document put, so every u1db atomic operation has to be +mapped to a couch document put. + +The atomic operations in the U1DB SQLite reference backend implementation may +be identified by the use of a context manager to access the underlying +database. A listing of the methods involved in each atomic operation are +depiced below. The top-level elements correpond to the atomic operations that +have to be mapped, and items on deeper levels of the list have to be +implemented in a way that all changes will be pushed with just one operation. + + * _set_replica_uid + * put_doc: + * _get_doc + * _put_and_update_indexes + * insert/update the document + * insert into transaction log + * delete_doc + * _get_doc + * _put_and_update_indexes + * get_doc_conflicts + * _get_conflicts + * _set_replica_gen_and_trans_id + * _do_set_replica_gen_and_trans_id + * _put_doc_if_newer + * _get_doc + * _validate_source (**) + * _get_replica_gen_and_trans_id + * cases: + * is newer: + * _prune_conflicts (**) + * _has_conflicts + * _delete_conflicts + * _put_and_update_indexes + * same content as: + * _put_and_update_indexes + * conflicted: + * _force_doc_sync_conflict + * _prune_conflicts + * _add_conflict + * _put_and_update_indexes + * _do_set_replica_gen_and_trans_id + * resolve_doc + * _get_doc + * cases: + * doc is superseded + * _put_and_update_indexes + * else + * _add_conflict + * _delete_conflicts + * delete_index + * create_index + +Couch views and update functions are used in order to achieve atomicity on the +Couch backend. Transactions are stored in the `u1db_transactions` field of the +couch document. Document's content and conflicted versions are stored as couch +document attachments with names, respectivelly, `u1db_content` and +`u1db_conflicts`. + +A map of methods and couch query URI can be found on the `./ddocs/README.txt` +document. + +Notes: + + * Currently, the couch backend does not implement indexing, so what is + depicted as `_put_and_update_indexes` above will be found as `_put_doc` in + the backend. + + * Conflict updates are part of document put using couch update functions, + and as such are part of the same atomic operation as document put. |