7311: Refactor PeerManager to be an interface

Signed-off-by: Matilda Clerke <matilda.clerke@consensys.net>

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/peertask/DefaultPeerManager.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright contributors to Hyperledger Besu.
+ *
+ * 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.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package org.hyperledger.besu.ethereum.eth.manager.peertask;
+
+import org.hyperledger.besu.ethereum.eth.manager.EthPeer;
+import org.hyperledger.besu.ethereum.p2p.peers.PeerId;
+
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.function.Predicate;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This is a simple PeerManager implementation that can be used the default implementation in most
+ * situations
+ */
+public class DefaultPeerManager implements PeerManager {
+  private static final Logger LOG = LoggerFactory.getLogger(DefaultPeerManager.class);
+
+  // use a synchronized map to ensure the map is never modified by multiple threads at once
+  private final Map<PeerId, EthPeer> ethPeersByPeerId =
+      Collections.synchronizedMap(new HashMap<>());
+
+  @Override
+  public EthPeer getPeer(final Predicate<EthPeer> filter) throws NoAvailablePeerException {
+    LOG.trace("Getting peer from pool of {} peers", ethPeersByPeerId.size());
+    return ethPeersByPeerId.values().stream()
+        .filter(filter)
+        .max(Comparator.naturalOrder())
+        .orElseThrow(NoAvailablePeerException::new);
+  }
+
+  @Override
+  public Optional<EthPeer> getPeerByPeerId(final PeerId peerId) {
+    return Optional.ofNullable(ethPeersByPeerId.get(peerId));
+  }
+
+  @Override
+  public void addPeer(final EthPeer ethPeer) {
+    ethPeersByPeerId.put(ethPeer.getConnection().getPeer(), ethPeer);
+  }
+
+  @Override
+  public void removePeer(final PeerId peerId) {
+    ethPeersByPeerId.remove(peerId);
+  }
+}

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/peertask/PeerManager.java

@@ -17,23 +17,11 @@ package org.hyperledger.besu.ethereum.eth.manager.peertask;
 import org.hyperledger.besu.ethereum.eth.manager.EthPeer;
 import org.hyperledger.besu.ethereum.p2p.peers.PeerId;
 
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.HashMap;
-import java.util.Map;
 import java.util.Optional;
 import java.util.function.Predicate;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
 /** "Manages" the EthPeers for the PeerTaskExecutor */
-public class PeerManager {
-  private static final Logger LOG = LoggerFactory.getLogger(PeerManager.class);
-
-  // use a synchronized map to ensure the map is never modified by multiple threads at once
-  private final Map<PeerId, EthPeer> ethPeersByPeerId =
-      Collections.synchronizedMap(new HashMap<>());
+public interface PeerManager {
 
   /**
    * Gets the highest reputation peer matching the supplies filter
@@ -42,23 +30,28 @@ public class PeerManager {
    * @return the highest reputation peer matching the supplies filter
    * @throws NoAvailablePeerException If there are no suitable peers
    */
-  public EthPeer getPeer(final Predicate<EthPeer> filter) throws NoAvailablePeerException {
-    LOG.trace("Getting peer from pool of {} peers", ethPeersByPeerId.size());
-    return ethPeersByPeerId.values().stream()
-        .filter(filter)
-        .max(Comparator.naturalOrder())
-        .orElseThrow(NoAvailablePeerException::new);
-  }
+  EthPeer getPeer(final Predicate<EthPeer> filter) throws NoAvailablePeerException;
 
-  public Optional<EthPeer> getPeerByPeerId(final PeerId peerId) {
-    return Optional.ofNullable(ethPeersByPeerId.get(peerId));
-  }
+  /**
+   * Attempts to get the EthPeer identified by peerId
+   *
+   * @param peerId the peerId of the desired EthPeer
+   * @return An Optional\<EthPeer\> containing the EthPeer identified by peerId if present in the
+   *     PeerManager, or empty otherwise
+   */
+  Optional<EthPeer> getPeerByPeerId(final PeerId peerId);
 
-  public void addPeer(final EthPeer ethPeer) {
-    ethPeersByPeerId.put(ethPeer.getConnection().getPeer(), ethPeer);
-  }
+  /**
+   * Add the supplied EthPeer to the PeerManager
+   *
+   * @param ethPeer the EthPeer to be added to the PeerManager
+   */
+  void addPeer(final EthPeer ethPeer);
 
-  public void removePeer(final PeerId peerId) {
-    ethPeersByPeerId.remove(peerId);
-  }
+  /**
+   * Remove the EthPeer identified by peerId from the PeerManager
+   *
+   * @param peerId the PeerId of the EthPeer to be removed from the PeerManager
+   */
+  void removePeer(final PeerId peerId);
 }

ethereum/eth/src/test/java/org/hyperledger/besu/ethereum/eth/manager/peertask/DefaultPeerManagerTest.java

@@ -28,13 +28,13 @@ import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-public class PeerManagerTest {
+public class DefaultPeerManagerTest {
 
-  public PeerManager peerManager;
+  public DefaultPeerManager peerManager;
 
   @BeforeEach
   public void beforeTest() {
-    peerManager = new PeerManager();
+    peerManager = new DefaultPeerManager();
   }
 
   @Test