- Exports:
- interface
wrpc:keyvalue/store@0.2.0-draft - interface
wrpc:keyvalue/atomics@0.2.0-draft
- interface
The set of errors which may be raised by functions in this package
-
The host does not recognize the store identifier requested.
-
The requesting component does not have access to the specified store (which may or may not exist).
-
Some implementation-specific error has occurred (e.g. I/O)
A response to a list-keys operation.
-
The list of keys returned by the query.
-
The continuation token to use to fetch the next page of keys. If this is `null`, then there are no more keys to fetch.
A bucket is a collection of key-value pairs. Each key-value pair is stored as a entry in the bucket, and the bucket itself acts as a collection of all these entries.
It is worth noting that the exact terminology for bucket in key-value stores can very depending on the specific implementation. For example:
- Amazon DynamoDB calls a collection of key-value pairs a table
- Redis has hashes, sets, and sorted sets as different types of collections
- Cassandra calls a collection of key-value pairs a column family
- MongoDB calls a collection of key-value pairs a collection
- Riak calls a collection of key-value pairs a bucket
- Memcached calls a collection of key-value pairs a slab
- Azure Cosmos DB calls a collection of key-value pairs a container
In this interface, we use the term bucket to refer to a collection of key-value pairs
Get the value associated with the specified key
The value is returned as an option. If the key-value pair exists in the
store, it returns Ok(value). If the key does not exist in the
store, it returns Ok(none).
If any other error occurs, it returns an Err(error).
- result<option<list<
u8>>,error>
Set the value associated with the key in the store. If the key already exists in the store, it overwrites the value.
If the key does not exist in the store, it creates a new key-value pair.
If any other error occurs, it returns an Err(error).
- result<_,
error>
Delete the key-value pair associated with the key in the store.
If the key does not exist in the store, it does nothing.
If any other error occurs, it returns an Err(error).
- result<_,
error>
Check if the key exists in the store.
If the key exists in the store, it returns Ok(true). If the key does
not exist in the store, it returns Ok(false).
If any other error occurs, it returns an Err(error).
- result<
bool,error>
Get all the keys in the store with an optional cursor (for use in pagination). It
returns a list of keys. Please note that for most KeyValue implementations, this is a
can be a very expensive operation and so it should be used judiciously. Implementations
can return any number of keys in a single response, but they should never attempt to
send more data than is reasonable (i.e. on a small edge device, this may only be a few
KB, while on a large machine this could be several MB). Any response should also return
a cursor that can be used to fetch the next page of keys. See the key-response record
for more information.
Note that the keys are not guaranteed to be returned in any particular order.
If the store is empty, it returns an empty list.
MAY show an out-of-date list of keys if there are concurrent writes to the store.
If any error occurs, it returns an Err(error).
- result<
key-response,error>
----
Atomically increment the value associated with the key in the store by the given delta. It returns the new value.
If the key does not exist in the store, it creates a new key-value pair with the value set to the given delta.
If any other error occurs, it returns an Err(error).
- result<
u64,error>