nickva commented on a change in pull request #2707: Set DbPrefix with value
allocated by erlfdb_hca
URL: https://github.com/apache/couchdb/pull/2707#discussion_r396566069
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File path: src/fabric/src/fabric2_fdb.erl
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@@ -177,10 +177,13 @@ create(#{} = Db0, Options) ->
layer_prefix := LayerPrefix
} = Db = ensure_current(Db0, false),
- % Eventually DbPrefix will be HCA allocated. For now
- % we're just using the DbName so that debugging is easier.
DbKey = erlfdb_tuple:pack({?ALL_DBS, DbName}, LayerPrefix),
- DbPrefix = erlfdb_tuple:pack({?DBS, DbName}, LayerPrefix),
+ DefDbPref = ?DEFAULT_DB_PREFIX,
+ AllDbPrefix = erlfdb_util:get(Options, db_prefix, DefDbPref),
+ DbId = erlfdb_tuple:pack({AllDbPrefix}, AllDbPrefix),
+ DbPrefixAllocator = erlfdb_hca:create(erlfdb_tuple:pack({DbId},
<<"hca">>)),
+ AllocPrefix = erlfdb_hca:allocate(DbPrefixAllocator, Tx),
+ DbPrefix = erlfdb_tuple:pack({?DBS, AllocPrefix}, LayerPrefix),
Review comment:
I wonder we could just keep the HCA counters right under the the
`LayerPrefix` ?
As in:
```
HCA = erlfdb_hca:create(erlfdb_tuple:pack({?DB_HCA}, LayerPrefix)),
AllocPrefix = erlfdb_hca:allocate(HCA, Tx),
DbPrefix = erlfdb_tuple:pack({?DBS, AllocPrefix}, LayerPrefix),
```
And then define `DB_HCA` to be in fabric2.hrl alongside `ALL_DBS`.
```
...
-define(ALL_DBS, 1).
-define(DB_HCA, 2).
```
Then we don't even need the `DEFAULT_DB_PREFIX` since we'd always be
creating these instances under `LayerPrefix` as well. In other words, they
won't clash with FDB directory nodes.
Would that work?
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