com.datastax.driver.core

Class GuavaCompatibility

java.lang.Object

com.datastax.driver.core.GuavaCompatibility

public abstract class GuavaCompatibility
extends Object

A compatibility layer to support a wide range of Guava versions.

The driver is compatible with Guava 16.0.1 or higher, but Guava 20 introduced incompatible breaking changes in its API, that could in turn be breaking for legacy driver clients if we simply upgraded our dependency. We don't want to increment our major version "just" for Guava (we have other changes planned).

Therefore we depend on Guava 19, which has both the deprecated and the new APIs, and detect the actual version at runtime in order to call the relevant methods.

This is a hack, and might not work with subsequent Guava releases; the real fix is to stop exposing Guava in our public API. We'll address that in version 4 of the driver.

Field Summary

Fields

Modifier and Type	Field and Description
static GuavaCompatibility	INSTANCE The unique instance of this class, that is compatible with the Guava version found in the classpath.

Constructor Summary

Constructors

Constructor and Description
GuavaCompatibility()

Method Summary

Modifier and Type	Method and Description
static void	init() Force the initialization of the class.
abstract boolean	isSupertypeOf(TypeToken<?> target, TypeToken<?> argument) Returns true if target is a supertype of argument.
abstract Executor	sameThreadExecutor() Returns an Executor that runs each task in the thread that invokes execute, as in ThreadPoolExecutor.CallerRunsPolicy.
abstract <I,O> ListenableFuture<O>	transformAsync(ListenableFuture<I> input, AsyncFunction<? super I,? extends O> function) Returns a new ListenableFuture whose result is asynchronously derived from the result of the given Future.
abstract <I,O> ListenableFuture<O>	transformAsync(ListenableFuture<I> input, AsyncFunction<? super I,? extends O> function, Executor executor) Returns a new ListenableFuture whose result is asynchronously derived from the result of the given Future.
abstract <V> ListenableFuture<V>	withFallback(ListenableFuture<? extends V> input, AsyncFunction<Throwable,V> fallback) Returns a Future whose result is taken from the given primary input or, if the primary input fails, from the Future provided by the fallback.
abstract <V> ListenableFuture<V>	withFallback(ListenableFuture<? extends V> input, AsyncFunction<Throwable,V> fallback, Executor executor) Returns a Future whose result is taken from the given primary input or, if the primary input fails, from the Future provided by the fallback.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

INSTANCE

public static final GuavaCompatibility INSTANCE

The unique instance of this class, that is compatible with the Guava version found in the classpath.

Constructor Detail

GuavaCompatibility

public GuavaCompatibility()

Method Detail

init

public static void init()

Force the initialization of the class. This should be called early to ensure a fast failure if an incompatible version of Guava is in the classpath (the driver code calls it when loading the Cluster class).

withFallback

public abstract <V> ListenableFuture<V> withFallback(ListenableFuture<? extends V> input,
                                                     AsyncFunction<Throwable,V> fallback)

Returns a Future whose result is taken from the given primary input or, if the primary input fails, from the Future provided by the fallback.

See Also:

Futures.withFallback(ListenableFuture, FutureFallback), Futures.catchingAsync(ListenableFuture, Class, AsyncFunction)

withFallback

public abstract <V> ListenableFuture<V> withFallback(ListenableFuture<? extends V> input,
                                                     AsyncFunction<Throwable,V> fallback,
                                                     Executor executor)

Returns a Future whose result is taken from the given primary input or, if the primary input fails, from the Future provided by the fallback.

See Also:

Futures.withFallback(ListenableFuture, FutureFallback, Executor), Futures.catchingAsync(ListenableFuture, Class, AsyncFunction, Executor)

transformAsync

public abstract <I,O> ListenableFuture<O> transformAsync(ListenableFuture<I> input,
                                                         AsyncFunction<? super I,? extends O> function)

Returns a new ListenableFuture whose result is asynchronously derived from the result of the given Future. More precisely, the returned Future takes its result from a Future produced by applying the given AsyncFunction to the result of the original Future.

See Also:

Futures.transform(ListenableFuture, AsyncFunction), Futures.transformAsync(ListenableFuture, AsyncFunction)

transformAsync

public abstract <I,O> ListenableFuture<O> transformAsync(ListenableFuture<I> input,
                                                         AsyncFunction<? super I,? extends O> function,
                                                         Executor executor)

Returns a new ListenableFuture whose result is asynchronously derived from the result of the given Future. More precisely, the returned Future takes its result from a Future produced by applying the given AsyncFunction to the result of the original Future.

See Also:

Futures.transform(ListenableFuture, AsyncFunction, Executor), Futures.transformAsync(ListenableFuture, AsyncFunction, Executor)

isSupertypeOf

public abstract boolean isSupertypeOf(TypeToken<?> target,
                                      TypeToken<?> argument)

Returns true if target is a supertype of argument. "Supertype" is defined according to the rules for type arguments introduced with Java generics.

See Also:

TypeToken.isAssignableFrom(Type), TypeToken.isSupertypeOf(Type)

sameThreadExecutor

public abstract Executor sameThreadExecutor()

Returns an Executor that runs each task in the thread that invokes execute, as in ThreadPoolExecutor.CallerRunsPolicy.

See Also:

MoreExecutors.sameThreadExecutor(), MoreExecutors.directExecutor()