1.9 KiB
Using Locks in ArangoDB
This documents summarizes the various locks and their usage. You should carefully read it in order to avoid dead-locks.
TRI_*_COLLECTIONS_VOCBASE (R/W)
Origin: TRI_vocbase_t, attribute _lock.
A vocbase contains collections, there names, and identifiers. Whenever you need to access these variables you need a read lock. Whenever you need to modify these variables you need a write lock.
If you need a TRI_COLLECTIONS_VOCBASE and a TRISTATUS_VOCBASE_COL, you must first grab the TRISTATUS_VOCBASE_COL and then the TRI_COLLECTIONS_VOCBASE.
Protected attributes of TRI_vocbase_t:
_collections_deadCollections_collectionsByName_collectionsById
TRI_*_STATUS_VOCBASE_COL (R/W)
Origin: TRI_vocbase_col_t, attribute _lock
This lock protects the status (loaded, unloaded) of the collection.
If you want to use a collection, you must call TRI_UseCollectionVocBase. This
will either load or manifest the collection and a read-lock is held when the
functions returns. You must call TRI_ReleaseCollectionVocBase, when you
finished using the collection. The functions that modify the status of
collection (load, unload, manifest) must grab a write-lock.
If you need a TRI_COLLECTIONS_VOCBASE and a TRISTATUS_VOCBASE_COL, you must first grab the TRISTATUS_VOCBASE_COL and then the TRI_COLLECTIONS_VOCBASE.
Protected attributes of TRI_vocbase_col_t:
_status_collection_name_path
TRI_*_SYNCHRONISER_WAITER_VOC_BASE (C)
TODO
TRI_*_JOURNAL_ENTRIES_DOC_COLLECTION (L)
TODO
TRI_*_DATAFILES_DOC_COLLECTION (R/W)
TODO
TRI_*_DOCUMENTS_INDEXES_PRIMARY_COLLECTION (R/W)
TODO