111 lines
4.1 KiB
Java
111 lines
4.1 KiB
Java
/*
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* Copyright 2021 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.buffer.api;
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import io.netty.buffer.api.internal.MemoryManagersOverride;
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import java.util.Optional;
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import java.util.ServiceLoader;
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import java.util.function.Supplier;
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import java.util.stream.Stream;
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/**
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* The MemoryManagers interface is the handle through which {@link BufferAllocator buffer allocators} access the low
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* level memory management APIs.
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* <p>
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* This is hidden behind this interface in order to make allocation and pool agnostic and reusable across buffer and
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* memory implementations.
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*/
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public interface MemoryManagers {
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/**
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* Get the default, or currently configured, memory managers instance.
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* @return A MemoryManagers instance.
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*/
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static MemoryManagers getManagers() {
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return MemoryManagersOverride.getManagers();
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}
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/**
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* Temporarily override the default configured memory managers instance.
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* <p>
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* Calls to {@link #getManagers()} from within the given supplier will get the given managers instance.
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*
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* @param managers Override the default configured managers instance with this instance.
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* @param supplier The supplier function to be called while the override is in place.
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* @param <T> The result type from the supplier.
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* @return The result from the supplier.
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*/
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static <T> T using(MemoryManagers managers, Supplier<T> supplier) {
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return MemoryManagersOverride.using(managers, supplier);
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}
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/**
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* Get a lazy-loading stream of all available memory managers.
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* <p>
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* Note: All available {@link MemoryManagers} instances are service loaded and instantiated on every call.
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*
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* @return A stream of providers of memory managers instances.
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*/
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static Stream<ServiceLoader.Provider<MemoryManagers>> getAllManagers() {
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var loader = ServiceLoader.load(MemoryManagers.class);
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return loader.stream();
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}
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/**
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* Find a {@link MemoryManagers} implementation by its {@linkplain #getImplementationName() implementation name}.
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* <p>
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* Note: All available {@link MemoryManagers} instances are service loaded and instantiated every time this
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* method is called.
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*
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* @param implementationName The named implementation to look for.
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* @return A {@link MemoryManagers} implementation, if any was found.
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*/
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static Optional<MemoryManagers> lookupImplementation(String implementationName) {
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return getAllManagers()
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.flatMap(provider -> {
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try {
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return Stream.ofNullable(provider.get());
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} catch (Exception e) {
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return Stream.empty();
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}
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})
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.filter(impl -> implementationName.equals(impl.getImplementationName()))
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.findFirst();
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}
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/**
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* Get a {@link MemoryManager} instance that is suitable for allocating on-heap {@link Buffer} instances.
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*
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* @return An on-heap {@link MemoryManager}.
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*/
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MemoryManager getHeapMemoryManager();
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/**
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* Get a {@link MemoryManager} instance that is suitable for allocating off-heap {@link Buffer} instances.
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*
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* @return An off-heap {@link MemoryManager}.
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*/
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MemoryManager getNativeMemoryManager();
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/**
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* Get the name for this implementation, which can be used for finding this particular implementation via the
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* {@link #lookupImplementation(String)} method.
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*
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* @return The name of this memory managers implementation.
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*/
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String getImplementationName();
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}
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