BP-65: Implement load balance for select bookie

bookkeeper-proto/src/main/proto/BookkeeperProtocol.proto

@@ -220,6 +220,10 @@ message GetBookieInfoResponse {
     required StatusCode status = 1;
     optional int64 totalDiskCapacity = 2;
     optional int64 freeDiskSpace = 3;
+    optional int32 journalIoUtil = 4;
+    optional int32 ledgerIoUtil = 5;
+    optional int32 cpuUsedRate = 6;
+    optional int64 writeBytePerSecond = 7;
 }
 
 message GetListOfEntriesOfLedgerResponse {

bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/BaseMetric.java

@@ -0,0 +1,78 @@
+/**
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.bookkeeper.bookie;
+
+public class BaseMetric {
+    int journalIoUtil;
+    int ledgerIoUtil;
+    int cpuUsedRate;
+    long writeBytePerSecond;
+
+    BaseMetric() {
+        journalIoUtil = -1;
+        ledgerIoUtil = -1;
+        cpuUsedRate = -1;
+        writeBytePerSecond = -1;
+    }
+
+    public int getJournalIoUtil() {
+        return journalIoUtil;
+    }
+
+    public void setJournalIoUtil(int journalIoUtil) {
+        this.journalIoUtil = journalIoUtil;
+    }
+
+    public int getLedgerIoUtil() {
+        return ledgerIoUtil;
+    }
+
+    public void setLedgerIoUtil(int ledgerIoUtil) {
+        this.ledgerIoUtil = ledgerIoUtil;
+    }
+
+    public int getCpuUsedRate() {
+        return cpuUsedRate;
+    }
+
+    public void setCpuUsedRate(int cpuUsedRate) {
+        this.cpuUsedRate = cpuUsedRate;
+    }
+
+    public long getWriteBytePerSecond() {
+        return writeBytePerSecond;
+    }
+
+    public void setWriteBytePerSecond(long writeBytePerSecond) {
+        this.writeBytePerSecond = writeBytePerSecond;
+    }
+
+    @Override
+    public String toString() {
+        return "BaseMetric{" +
+            "journalIoUtil=" + journalIoUtil +
+            ", ledgerIoUtil=" + ledgerIoUtil +
+            ", cpuUsedRate=" + cpuUsedRate +
+            ", writeBytePerSecond=" + writeBytePerSecond +
+            '}';
+    }
+}