com.yahoo.bullet.storage

Interface Criteria<T,R>

Type Parameters:

T - The specific type used by this Criteria as arguments.

R - The specific type returned by this Criteria when applied to a storage. Encapsulates the idea of criteria that can apply themselves to a StorageManager query. This can be anything like the WHERE clause of a SQL query for relational storages or something that modifies the storage or whatever else. It provides the get(StorageManager) method to retrieve the data from the storage as a key-value mapping to the raw data stored. The Criteria can also wrap its results in its own format when using the retrieve(StorageManager) interface to return objects of an expected type.

A specific Criteria is intended to be implemented along with the particular StorageManager so that non-public interfaces can be shared between them.

In order to allow arbitrary changes or queries to the storage, the apply(StorageManager, Object) method is also provided. This method is intended to be used for anything dealing with the storage, including retrieval. The specific arguments for the query are left to the specific criteria.

All Known Implementing Classes:

MultiMemoryCountingCriteria

public interface Criteria<T,R>

Method Summary

Modifier and Type	Method and Description
<V extends Serializable> CompletableFuture<R>	apply(StorageManager<V> storage, T query) Applies the criteria to the StorageManager.
static <V extends Serializable,S extends StorageManager> S	checkType(StorageManager<V> storage, Class<S> klazz) Utility method to help check and cast if a given storage is of the given type.
<V extends Serializable> CompletableFuture<Map<String,V>>	get(StorageManager<V> storage) Retrieves data from the given StorageManager as a CompletableFuture resolving to a key-value mapping of the raw data stored in the storage.
<V extends Serializable> CompletableFuture<R>	retrieve(StorageManager<V> storage) Retrieves data from the given StorageManager as a CompletableFuture resolving to the specific return type of this Criteria.

Method Detail

get

<V extends Serializable> CompletableFuture<Map<String,V>> get(StorageManager<V> storage)

Retrieves data from the given StorageManager as a CompletableFuture resolving to a key-value mapping of the raw data stored in the storage.

Type Parameters:

V - The type of the data stored in the storage.

Parameters:

storage - The StorageManager to retrieve data from.

Returns:

A CompletableFuture that resolves to a Map of String keys to the raw data in the storage.

retrieve

<V extends Serializable> CompletableFuture<R> retrieve(StorageManager<V> storage)

Retrieves data from the given StorageManager as a CompletableFuture resolving to the specific return type of this Criteria.

Type Parameters:

V - The type of the data stored in the storage.

Parameters:

storage - The StorageManager to retrieve data from.

Returns:

A CompletableFuture that resolves to the return type of this Criteria.

apply

<V extends Serializable> CompletableFuture<R> apply(StorageManager<V> storage,
                                                    T query)

Applies the criteria to the StorageManager. This is left to the specific criteria to choose what to do.

Type Parameters:

V - The type of the data stored in the storage.

Parameters:

storage - The StorageManager to apply this to.

query - The specific query to apply to this Criteria.

Returns:

A CompletableFuture that resolves to the return type of this Criteria.

checkType

static <V extends Serializable,S extends StorageManager> S checkType(StorageManager<V> storage,
                                                                     Class<S> klazz)

Utility method to help check and cast if a given storage is of the given type. It does not check generic types for the storage.

Type Parameters:

V - The type of the storage.

S - The super-type of the storage.

Parameters:

storage - The storage to check.

klazz - The non-null super-type that the given storage is supposed to inherit from.

Returns:

The casted storage.

Throws:

UnsupportedOperationException - if the storage is not an instance of the given class.