Repository: hbase Updated Branches: refs/heads/master 6462a615c -> 243fe287b
HBASE-16219 addendum move MasterMetaBootstrap to the right place Project: http://git-wip-us.apache.org/repos/asf/hbase/repo Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/243fe287 Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/243fe287 Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/243fe287 Branch: refs/heads/master Commit: 243fe287b9055f4a16dda0175d5247d2d7a6b81e Parents: 6462a61 Author: zhangduo <zhang...@apache.org> Authored: Fri Jul 15 09:56:01 2016 +0800 Committer: zhangduo <zhang...@apache.org> Committed: Fri Jul 15 09:58:17 2016 +0800 ---------------------------------------------------------------------- .../hadoop/hbase/MasterMetaBootstrap.java | 257 ------------------- .../hbase/master/MasterMetaBootstrap.java | 257 +++++++++++++++++++ 2 files changed, 257 insertions(+), 257 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/hbase/blob/243fe287/hbase-server/src/main/java/org/apache/hadoop/hbase/MasterMetaBootstrap.java ---------------------------------------------------------------------- diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/MasterMetaBootstrap.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/MasterMetaBootstrap.java deleted file mode 100644 index 0504555..0000000 --- a/hbase-server/src/main/java/org/apache/hadoop/hbase/MasterMetaBootstrap.java +++ /dev/null @@ -1,257 +0,0 @@ -/** - * - * 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.hadoop.hbase.master; - -import java.io.IOException; -import java.util.Arrays; -import java.util.Collections; -import java.util.List; -import java.util.HashSet; -import java.util.Set; - -import org.apache.commons.logging.Log; -import org.apache.commons.logging.LogFactory; -import org.apache.hadoop.hbase.HConstants; -import org.apache.hadoop.hbase.HRegionInfo; -import org.apache.hadoop.hbase.ServerName; -import org.apache.hadoop.hbase.TableName; -import org.apache.hadoop.hbase.classification.InterfaceAudience; -import org.apache.hadoop.hbase.client.RegionReplicaUtil; -import org.apache.hadoop.hbase.client.TableState; -import org.apache.hadoop.hbase.monitoring.MonitoredTask; -import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos.SplitLogTask.RecoveryMode; -import org.apache.hadoop.hbase.zookeeper.MetaTableLocator; -import org.apache.hadoop.hbase.zookeeper.ZKUtil; -import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher; -import org.apache.zookeeper.KeeperException; - -/** - * Used by the HMaster on startup to split meta logs and assign the meta table. - */ -@InterfaceAudience.Private -public class MasterMetaBootstrap { - private static final Log LOG = LogFactory.getLog(MasterMetaBootstrap.class); - - private final MonitoredTask status; - private final HMaster master; - - private Set<ServerName> previouslyFailedServers; - private Set<ServerName> previouslyFailedMetaRSs; - - public MasterMetaBootstrap(final HMaster master, final MonitoredTask status) { - this.master = master; - this.status = status; - } - - public void splitMetaLogsBeforeAssignment() throws IOException, KeeperException { - // get a list for previously failed RS which need log splitting work - // we recover hbase:meta region servers inside master initialization and - // handle other failed servers in SSH in order to start up master node ASAP - previouslyFailedServers = master.getMasterWalManager().getFailedServersFromLogFolders(); - - // log splitting for hbase:meta server - ServerName oldMetaServerLocation = master.getMetaTableLocator() - .getMetaRegionLocation(master.getZooKeeper()); - if (oldMetaServerLocation != null && previouslyFailedServers.contains(oldMetaServerLocation)) { - splitMetaLogBeforeAssignment(oldMetaServerLocation); - // Note: we can't remove oldMetaServerLocation from previousFailedServers list because it - // may also host user regions - } - previouslyFailedMetaRSs = getPreviouselyFailedMetaServersFromZK(); - // need to use union of previouslyFailedMetaRSs recorded in ZK and previouslyFailedServers - // instead of previouslyFailedMetaRSs alone to address the following two situations: - // 1) the chained failure situation(recovery failed multiple times in a row). - // 2) master get killed right before it could delete the recovering hbase:meta from ZK while the - // same server still has non-meta wals to be replayed so that - // removeStaleRecoveringRegionsFromZK can't delete the stale hbase:meta region - // Passing more servers into splitMetaLog is all right. If a server doesn't have hbase:meta wal, - // there is no op for the server. - previouslyFailedMetaRSs.addAll(previouslyFailedServers); - } - - public void assignMeta() throws InterruptedException, IOException, KeeperException { - assignMeta(previouslyFailedMetaRSs, HRegionInfo.DEFAULT_REPLICA_ID); - } - - public void processDeadServers() throws IOException { - // Master has recovered hbase:meta region server and we put - // other failed region servers in a queue to be handled later by SSH - for (ServerName tmpServer : previouslyFailedServers) { - master.getServerManager().processDeadServer(tmpServer, true); - } - } - - public void assignMetaReplicas() - throws IOException, InterruptedException, KeeperException { - int numReplicas = master.getConfiguration().getInt(HConstants.META_REPLICAS_NUM, - HConstants.DEFAULT_META_REPLICA_NUM); - final Set<ServerName> EMPTY_SET = new HashSet<ServerName>(); - for (int i = 1; i < numReplicas; i++) { - assignMeta(EMPTY_SET, i); - } - unassignExcessMetaReplica(numReplicas); - } - - private void splitMetaLogBeforeAssignment(ServerName currentMetaServer) throws IOException { - if (RecoveryMode.LOG_REPLAY == master.getMasterWalManager().getLogRecoveryMode()) { - // In log replay mode, we mark hbase:meta region as recovering in ZK - master.getMasterWalManager().prepareLogReplay(currentMetaServer, - Collections.<HRegionInfo>singleton(HRegionInfo.FIRST_META_REGIONINFO)); - } else { - // In recovered.edits mode: create recovered edits file for hbase:meta server - master.getMasterWalManager().splitMetaLog(currentMetaServer); - } - } - - private void unassignExcessMetaReplica(int numMetaReplicasConfigured) { - final ZooKeeperWatcher zooKeeper = master.getZooKeeper(); - // unassign the unneeded replicas (for e.g., if the previous master was configured - // with a replication of 3 and now it is 2, we need to unassign the 1 unneeded replica) - try { - List<String> metaReplicaZnodes = zooKeeper.getMetaReplicaNodes(); - for (String metaReplicaZnode : metaReplicaZnodes) { - int replicaId = zooKeeper.getMetaReplicaIdFromZnode(metaReplicaZnode); - if (replicaId >= numMetaReplicasConfigured) { - RegionState r = MetaTableLocator.getMetaRegionState(zooKeeper, replicaId); - LOG.info("Closing excess replica of meta region " + r.getRegion()); - // send a close and wait for a max of 30 seconds - ServerManager.closeRegionSilentlyAndWait(master.getClusterConnection(), - r.getServerName(), r.getRegion(), 30000); - ZKUtil.deleteNode(zooKeeper, zooKeeper.getZNodeForReplica(replicaId)); - } - } - } catch (Exception ex) { - // ignore the exception since we don't want the master to be wedged due to potential - // issues in the cleanup of the extra regions. We can do that cleanup via hbck or manually - LOG.warn("Ignoring exception " + ex); - } - } - - /** - * Check <code>hbase:meta</code> is assigned. If not, assign it. - */ - protected void assignMeta(Set<ServerName> previouslyFailedMetaRSs, int replicaId) - throws InterruptedException, IOException, KeeperException { - final AssignmentManager assignmentManager = master.getAssignmentManager(); - - // Work on meta region - int assigned = 0; - long timeout = master.getConfiguration().getLong("hbase.catalog.verification.timeout", 1000); - if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { - status.setStatus("Assigning hbase:meta region"); - } else { - status.setStatus("Assigning hbase:meta region, replicaId " + replicaId); - } - - // Get current meta state from zk. - RegionState metaState = MetaTableLocator.getMetaRegionState(master.getZooKeeper(), replicaId); - HRegionInfo hri = RegionReplicaUtil.getRegionInfoForReplica(HRegionInfo.FIRST_META_REGIONINFO, - replicaId); - RegionStates regionStates = assignmentManager.getRegionStates(); - regionStates.createRegionState(hri, metaState.getState(), - metaState.getServerName(), null); - - if (!metaState.isOpened() || !master.getMetaTableLocator().verifyMetaRegionLocation( - master.getClusterConnection(), master.getZooKeeper(), timeout, replicaId)) { - ServerName currentMetaServer = metaState.getServerName(); - if (master.getServerManager().isServerOnline(currentMetaServer)) { - if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { - LOG.info("Meta was in transition on " + currentMetaServer); - } else { - LOG.info("Meta with replicaId " + replicaId + " was in transition on " + - currentMetaServer); - } - assignmentManager.processRegionsInTransition(Collections.singletonList(metaState)); - } else { - if (currentMetaServer != null) { - if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { - splitMetaLogBeforeAssignment(currentMetaServer); - regionStates.logSplit(HRegionInfo.FIRST_META_REGIONINFO); - previouslyFailedMetaRSs.add(currentMetaServer); - } - } - LOG.info("Re-assigning hbase:meta with replicaId, " + replicaId + - " it was on " + currentMetaServer); - assignmentManager.assignMeta(hri); - } - assigned++; - } - - if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { - // TODO: should we prevent from using state manager before meta was initialized? - // tableStateManager.start(); - master.getTableStateManager() - .setTableState(TableName.META_TABLE_NAME, TableState.State.ENABLED); - } - - if ((RecoveryMode.LOG_REPLAY == master.getMasterWalManager().getLogRecoveryMode()) - && (!previouslyFailedMetaRSs.isEmpty())) { - // replay WAL edits mode need new hbase:meta RS is assigned firstly - status.setStatus("replaying log for Meta Region"); - master.getMasterWalManager().splitMetaLog(previouslyFailedMetaRSs); - } - - assignmentManager.setEnabledTable(TableName.META_TABLE_NAME); - master.getTableStateManager().start(); - - // Make sure a hbase:meta location is set. We need to enable SSH here since - // if the meta region server is died at this time, we need it to be re-assigned - // by SSH so that system tables can be assigned. - // No need to wait for meta is assigned = 0 when meta is just verified. - if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) enableCrashedServerProcessing(assigned != 0); - LOG.info("hbase:meta with replicaId " + replicaId + " assigned=" + assigned + ", location=" - + master.getMetaTableLocator().getMetaRegionLocation(master.getZooKeeper(), replicaId)); - status.setStatus("META assigned."); - } - - private void enableCrashedServerProcessing(final boolean waitForMeta) - throws IOException, InterruptedException { - // If crashed server processing is disabled, we enable it and expire those dead but not expired - // servers. This is required so that if meta is assigning to a server which dies after - // assignMeta starts assignment, ServerCrashProcedure can re-assign it. Otherwise, we will be - // stuck here waiting forever if waitForMeta is specified. - if (!master.isServerCrashProcessingEnabled()) { - master.setServerCrashProcessingEnabled(true); - master.getServerManager().processQueuedDeadServers(); - } - - if (waitForMeta) { - master.getMetaTableLocator().waitMetaRegionLocation(master.getZooKeeper()); - } - } - - /** - * This function returns a set of region server names under hbase:meta recovering region ZK node - * @return Set of meta server names which were recorded in ZK - */ - private Set<ServerName> getPreviouselyFailedMetaServersFromZK() throws KeeperException { - final ZooKeeperWatcher zooKeeper = master.getZooKeeper(); - Set<ServerName> result = new HashSet<ServerName>(); - String metaRecoveringZNode = ZKUtil.joinZNode(zooKeeper.recoveringRegionsZNode, - HRegionInfo.FIRST_META_REGIONINFO.getEncodedName()); - List<String> regionFailedServers = ZKUtil.listChildrenNoWatch(zooKeeper, metaRecoveringZNode); - if (regionFailedServers == null) return result; - - for (String failedServer : regionFailedServers) { - ServerName server = ServerName.parseServerName(failedServer); - result.add(server); - } - return result; - } -} http://git-wip-us.apache.org/repos/asf/hbase/blob/243fe287/hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterMetaBootstrap.java ---------------------------------------------------------------------- diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterMetaBootstrap.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterMetaBootstrap.java new file mode 100644 index 0000000..0504555 --- /dev/null +++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/MasterMetaBootstrap.java @@ -0,0 +1,257 @@ +/** + * + * 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.hadoop.hbase.master; + +import java.io.IOException; +import java.util.Arrays; +import java.util.Collections; +import java.util.List; +import java.util.HashSet; +import java.util.Set; + +import org.apache.commons.logging.Log; +import org.apache.commons.logging.LogFactory; +import org.apache.hadoop.hbase.HConstants; +import org.apache.hadoop.hbase.HRegionInfo; +import org.apache.hadoop.hbase.ServerName; +import org.apache.hadoop.hbase.TableName; +import org.apache.hadoop.hbase.classification.InterfaceAudience; +import org.apache.hadoop.hbase.client.RegionReplicaUtil; +import org.apache.hadoop.hbase.client.TableState; +import org.apache.hadoop.hbase.monitoring.MonitoredTask; +import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos.SplitLogTask.RecoveryMode; +import org.apache.hadoop.hbase.zookeeper.MetaTableLocator; +import org.apache.hadoop.hbase.zookeeper.ZKUtil; +import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher; +import org.apache.zookeeper.KeeperException; + +/** + * Used by the HMaster on startup to split meta logs and assign the meta table. + */ +@InterfaceAudience.Private +public class MasterMetaBootstrap { + private static final Log LOG = LogFactory.getLog(MasterMetaBootstrap.class); + + private final MonitoredTask status; + private final HMaster master; + + private Set<ServerName> previouslyFailedServers; + private Set<ServerName> previouslyFailedMetaRSs; + + public MasterMetaBootstrap(final HMaster master, final MonitoredTask status) { + this.master = master; + this.status = status; + } + + public void splitMetaLogsBeforeAssignment() throws IOException, KeeperException { + // get a list for previously failed RS which need log splitting work + // we recover hbase:meta region servers inside master initialization and + // handle other failed servers in SSH in order to start up master node ASAP + previouslyFailedServers = master.getMasterWalManager().getFailedServersFromLogFolders(); + + // log splitting for hbase:meta server + ServerName oldMetaServerLocation = master.getMetaTableLocator() + .getMetaRegionLocation(master.getZooKeeper()); + if (oldMetaServerLocation != null && previouslyFailedServers.contains(oldMetaServerLocation)) { + splitMetaLogBeforeAssignment(oldMetaServerLocation); + // Note: we can't remove oldMetaServerLocation from previousFailedServers list because it + // may also host user regions + } + previouslyFailedMetaRSs = getPreviouselyFailedMetaServersFromZK(); + // need to use union of previouslyFailedMetaRSs recorded in ZK and previouslyFailedServers + // instead of previouslyFailedMetaRSs alone to address the following two situations: + // 1) the chained failure situation(recovery failed multiple times in a row). + // 2) master get killed right before it could delete the recovering hbase:meta from ZK while the + // same server still has non-meta wals to be replayed so that + // removeStaleRecoveringRegionsFromZK can't delete the stale hbase:meta region + // Passing more servers into splitMetaLog is all right. If a server doesn't have hbase:meta wal, + // there is no op for the server. + previouslyFailedMetaRSs.addAll(previouslyFailedServers); + } + + public void assignMeta() throws InterruptedException, IOException, KeeperException { + assignMeta(previouslyFailedMetaRSs, HRegionInfo.DEFAULT_REPLICA_ID); + } + + public void processDeadServers() throws IOException { + // Master has recovered hbase:meta region server and we put + // other failed region servers in a queue to be handled later by SSH + for (ServerName tmpServer : previouslyFailedServers) { + master.getServerManager().processDeadServer(tmpServer, true); + } + } + + public void assignMetaReplicas() + throws IOException, InterruptedException, KeeperException { + int numReplicas = master.getConfiguration().getInt(HConstants.META_REPLICAS_NUM, + HConstants.DEFAULT_META_REPLICA_NUM); + final Set<ServerName> EMPTY_SET = new HashSet<ServerName>(); + for (int i = 1; i < numReplicas; i++) { + assignMeta(EMPTY_SET, i); + } + unassignExcessMetaReplica(numReplicas); + } + + private void splitMetaLogBeforeAssignment(ServerName currentMetaServer) throws IOException { + if (RecoveryMode.LOG_REPLAY == master.getMasterWalManager().getLogRecoveryMode()) { + // In log replay mode, we mark hbase:meta region as recovering in ZK + master.getMasterWalManager().prepareLogReplay(currentMetaServer, + Collections.<HRegionInfo>singleton(HRegionInfo.FIRST_META_REGIONINFO)); + } else { + // In recovered.edits mode: create recovered edits file for hbase:meta server + master.getMasterWalManager().splitMetaLog(currentMetaServer); + } + } + + private void unassignExcessMetaReplica(int numMetaReplicasConfigured) { + final ZooKeeperWatcher zooKeeper = master.getZooKeeper(); + // unassign the unneeded replicas (for e.g., if the previous master was configured + // with a replication of 3 and now it is 2, we need to unassign the 1 unneeded replica) + try { + List<String> metaReplicaZnodes = zooKeeper.getMetaReplicaNodes(); + for (String metaReplicaZnode : metaReplicaZnodes) { + int replicaId = zooKeeper.getMetaReplicaIdFromZnode(metaReplicaZnode); + if (replicaId >= numMetaReplicasConfigured) { + RegionState r = MetaTableLocator.getMetaRegionState(zooKeeper, replicaId); + LOG.info("Closing excess replica of meta region " + r.getRegion()); + // send a close and wait for a max of 30 seconds + ServerManager.closeRegionSilentlyAndWait(master.getClusterConnection(), + r.getServerName(), r.getRegion(), 30000); + ZKUtil.deleteNode(zooKeeper, zooKeeper.getZNodeForReplica(replicaId)); + } + } + } catch (Exception ex) { + // ignore the exception since we don't want the master to be wedged due to potential + // issues in the cleanup of the extra regions. We can do that cleanup via hbck or manually + LOG.warn("Ignoring exception " + ex); + } + } + + /** + * Check <code>hbase:meta</code> is assigned. If not, assign it. + */ + protected void assignMeta(Set<ServerName> previouslyFailedMetaRSs, int replicaId) + throws InterruptedException, IOException, KeeperException { + final AssignmentManager assignmentManager = master.getAssignmentManager(); + + // Work on meta region + int assigned = 0; + long timeout = master.getConfiguration().getLong("hbase.catalog.verification.timeout", 1000); + if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { + status.setStatus("Assigning hbase:meta region"); + } else { + status.setStatus("Assigning hbase:meta region, replicaId " + replicaId); + } + + // Get current meta state from zk. + RegionState metaState = MetaTableLocator.getMetaRegionState(master.getZooKeeper(), replicaId); + HRegionInfo hri = RegionReplicaUtil.getRegionInfoForReplica(HRegionInfo.FIRST_META_REGIONINFO, + replicaId); + RegionStates regionStates = assignmentManager.getRegionStates(); + regionStates.createRegionState(hri, metaState.getState(), + metaState.getServerName(), null); + + if (!metaState.isOpened() || !master.getMetaTableLocator().verifyMetaRegionLocation( + master.getClusterConnection(), master.getZooKeeper(), timeout, replicaId)) { + ServerName currentMetaServer = metaState.getServerName(); + if (master.getServerManager().isServerOnline(currentMetaServer)) { + if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { + LOG.info("Meta was in transition on " + currentMetaServer); + } else { + LOG.info("Meta with replicaId " + replicaId + " was in transition on " + + currentMetaServer); + } + assignmentManager.processRegionsInTransition(Collections.singletonList(metaState)); + } else { + if (currentMetaServer != null) { + if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { + splitMetaLogBeforeAssignment(currentMetaServer); + regionStates.logSplit(HRegionInfo.FIRST_META_REGIONINFO); + previouslyFailedMetaRSs.add(currentMetaServer); + } + } + LOG.info("Re-assigning hbase:meta with replicaId, " + replicaId + + " it was on " + currentMetaServer); + assignmentManager.assignMeta(hri); + } + assigned++; + } + + if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) { + // TODO: should we prevent from using state manager before meta was initialized? + // tableStateManager.start(); + master.getTableStateManager() + .setTableState(TableName.META_TABLE_NAME, TableState.State.ENABLED); + } + + if ((RecoveryMode.LOG_REPLAY == master.getMasterWalManager().getLogRecoveryMode()) + && (!previouslyFailedMetaRSs.isEmpty())) { + // replay WAL edits mode need new hbase:meta RS is assigned firstly + status.setStatus("replaying log for Meta Region"); + master.getMasterWalManager().splitMetaLog(previouslyFailedMetaRSs); + } + + assignmentManager.setEnabledTable(TableName.META_TABLE_NAME); + master.getTableStateManager().start(); + + // Make sure a hbase:meta location is set. We need to enable SSH here since + // if the meta region server is died at this time, we need it to be re-assigned + // by SSH so that system tables can be assigned. + // No need to wait for meta is assigned = 0 when meta is just verified. + if (replicaId == HRegionInfo.DEFAULT_REPLICA_ID) enableCrashedServerProcessing(assigned != 0); + LOG.info("hbase:meta with replicaId " + replicaId + " assigned=" + assigned + ", location=" + + master.getMetaTableLocator().getMetaRegionLocation(master.getZooKeeper(), replicaId)); + status.setStatus("META assigned."); + } + + private void enableCrashedServerProcessing(final boolean waitForMeta) + throws IOException, InterruptedException { + // If crashed server processing is disabled, we enable it and expire those dead but not expired + // servers. This is required so that if meta is assigning to a server which dies after + // assignMeta starts assignment, ServerCrashProcedure can re-assign it. Otherwise, we will be + // stuck here waiting forever if waitForMeta is specified. + if (!master.isServerCrashProcessingEnabled()) { + master.setServerCrashProcessingEnabled(true); + master.getServerManager().processQueuedDeadServers(); + } + + if (waitForMeta) { + master.getMetaTableLocator().waitMetaRegionLocation(master.getZooKeeper()); + } + } + + /** + * This function returns a set of region server names under hbase:meta recovering region ZK node + * @return Set of meta server names which were recorded in ZK + */ + private Set<ServerName> getPreviouselyFailedMetaServersFromZK() throws KeeperException { + final ZooKeeperWatcher zooKeeper = master.getZooKeeper(); + Set<ServerName> result = new HashSet<ServerName>(); + String metaRecoveringZNode = ZKUtil.joinZNode(zooKeeper.recoveringRegionsZNode, + HRegionInfo.FIRST_META_REGIONINFO.getEncodedName()); + List<String> regionFailedServers = ZKUtil.listChildrenNoWatch(zooKeeper, metaRecoveringZNode); + if (regionFailedServers == null) return result; + + for (String failedServer : regionFailedServers) { + ServerName server = ServerName.parseServerName(failedServer); + result.add(server); + } + return result; + } +}