net.dv8tion.jda.api.sharding.ThreadPoolProvider Maven / Gradle / Ivy
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/*
* Copyright 2015 Austin Keener, Michael Ritter, Florian Spieß, and the JDA contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.dv8tion.jda.api.sharding;
import net.dv8tion.jda.internal.utils.Checks;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.concurrent.ExecutorService;
import java.util.function.IntFunction;
/**
* Called by {@link DefaultShardManager} when building a JDA instance.
*
Every time a JDA instance is built, the manager will first call {@link #provide(int)} followed by
* a call to {@link #shouldShutdownAutomatically(int)}.
*
* @param
* The type of executor
*/
public interface ThreadPoolProvider
{
/**
* Provides an instance of the specified executor, or null
*
* @param shardId
* The current shard id
*
* @return The Executor Service
*/
@Nullable
T provide(int shardId);
/**
* Whether the previously provided executor should be shutdown by {@link net.dv8tion.jda.api.JDA#shutdown()}.
*
* @param shardId
* The current shard id
*
* @return True, if the executor should be shutdown by JDA
*/
default boolean shouldShutdownAutomatically(int shardId)
{
return false;
}
/**
* Provider that initializes with a {@link DefaultShardManagerBuilder#setShardsTotal(int) shard_total}
* and provides the same pool to share between shards.
*
* @param init
* Function to initialize the shared pool, called with the shard total
*
* @param
* The type of executor
*
* @return The lazy pool provider
*/
@Nonnull
static LazySharedProvider lazy(@Nonnull IntFunction init)
{
Checks.notNull(init, "Initializer");
return new LazySharedProvider<>(init);
}
final class LazySharedProvider implements ThreadPoolProvider
{
private final IntFunction initializer;
private T pool;
LazySharedProvider(@Nonnull IntFunction initializer)
{
this.initializer = initializer;
}
/**
* Called with the shard total to initialize the shared pool.
*
* This also destroys the temporary pool created for fetching the recommended shard total.
*
* @param shardTotal
* The shard total
*/
public synchronized void init(int shardTotal)
{
if (pool == null)
pool = initializer.apply(shardTotal);
}
/**
* Shuts down the shared pool and the temporary pool.
*/
public synchronized void shutdown()
{
if (pool != null)
{
pool.shutdown();
pool = null;
}
}
/**
* Provides the initialized pool or the temporary pool if not initialized yet.
*
* @param shardId
* The current shard id
*
* @return The thread pool instance
*/
@Nullable
@Override
public synchronized T provide(int shardId)
{
return pool;
}
}
}