linyiqun commented on a change in pull request #1613:
URL: https://github.com/apache/ozone/pull/1613#discussion_r529604167
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File path:
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/request/upgrade/OMPrepareRequest.java
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@@ -0,0 +1,108 @@
+package org.apache.hadoop.ozone.om.request.upgrade;
+
+import org.apache.hadoop.hdds.ratis.RatisUpgradeUtils;
+import org.apache.hadoop.ozone.om.OzoneManager;
+import org.apache.hadoop.ozone.om.exceptions.OMException;
+import org.apache.hadoop.ozone.om.ratis.OzoneManagerRatisServer;
+import org.apache.hadoop.ozone.om.ratis.OzoneManagerStateMachine;
+import org.apache.hadoop.ozone.om.ratis.utils.OzoneManagerDoubleBufferHelper;
+import org.apache.hadoop.ozone.om.request.OMClientRequest;
+import org.apache.hadoop.ozone.om.request.util.OmResponseUtil;
+import org.apache.hadoop.ozone.om.response.OMClientResponse;
+import org.apache.hadoop.ozone.om.response.upgrade.OMPrepareResponse;
+import
org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.PrepareResponse;
+import
org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.OMRequest;
+import
org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.OMResponse;
+import static
org.apache.hadoop.ozone.protocol.proto.OzoneManagerProtocolProtos.Type;
+
+import org.apache.ratis.server.impl.RaftServerImpl;
+import org.apache.ratis.server.impl.RaftServerProxy;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+
+/**
+ * OM Request used to flush all transactions to disk, take a DB snapshot, and
+ * purge the logs, leaving Ratis in a clean state without unapplied log
+ * entries. This prepares the OM for upgrades/downgrades so that no request
+ * in the log is applied to the database in the old version of the code in one
+ * OM, and the new version of the code on another OM.
+ */
+public class OMPrepareRequest extends OMClientRequest {
+ private static final Logger LOG =
+ LoggerFactory.getLogger(OMPrepareRequest.class);
+
+ // Allow double buffer this many seconds to flush all transactions before
+ // returning an error to the caller.
+ private static final long DOUBLE_BUFFER_FLUSH_TIMEOUT_SECONDS = 5 * 60;
+ // Time between checks to see if double buffer finished flushing.
+ private static final long DOUBLE_BUFFER_FLUSH_CHECK_SECONDS = 1;
+
+ public OMPrepareRequest(OMRequest omRequest) {
+ super(omRequest);
+ }
+
+ @Override
+ public OMClientResponse validateAndUpdateCache(
+ OzoneManager ozoneManager, long transactionLogIndex,
+ OzoneManagerDoubleBufferHelper ozoneManagerDoubleBufferHelper) {
+
+ LOG.info("Received prepare request with log index {}",
transactionLogIndex);
+
+ OMResponse.Builder responseBuilder =
+ OmResponseUtil.getOMResponseBuilder(getOmRequest());
+ responseBuilder.setCmdType(Type.Prepare);
+ OMClientResponse response = null;
+
+ try {
+ // Create response.
+ PrepareResponse omResponse = PrepareResponse.newBuilder()
+ .setTxnID(transactionLogIndex)
+ .build();
+ responseBuilder.setPrepareForUpgradeResponse(omResponse);
+ response = new OMPrepareResponse(responseBuilder.build());
+
+ // Add response to double buffer before clearing logs.
+ // This guarantees the log index of this request will be the same as
+ // the snapshot index in the prepared state.
+ ozoneManagerDoubleBufferHelper.add(response, transactionLogIndex);
+
+ OzoneManagerRatisServer omRatisServer = ozoneManager.getOmRatisServer();
+ OzoneManagerStateMachine omStateMachine =
+ omRatisServer.getOmStateMachine();
+ RaftServerProxy server = (RaftServerProxy) omRatisServer.getServer();
+ RaftServerImpl serverImpl =
+ server.getImpl(omRatisServer.getRaftGroup().getGroupId());
+
+ // Wait for outstanding double buffer entries to flush to disk,
+ // so they will not be purged from the log before being persisted to
+ // the DB.
+ RatisUpgradeUtils.waitForAllTxnsApplied(omStateMachine, serverImpl,
+ DOUBLE_BUFFER_FLUSH_TIMEOUT_SECONDS,
+ DOUBLE_BUFFER_FLUSH_CHECK_SECONDS);
Review comment:
Transaction entry added in double buffer is async flushed to db. Shall
we pass transactionLogIndex to double check and make sure previous txns be
applied.
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