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NoSQL Database Server - supplies build and runtime support for the server (store) side of the Oracle NoSQL Database.
/*-
* Copyright (C) 2011, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This file was distributed by Oracle as part of a version of Oracle NoSQL
* Database made available at:
*
* http://www.oracle.com/technetwork/database/database-technologies/nosqldb/downloads/index.html
*
* Please see the LICENSE file included in the top-level directory of the
* appropriate version of Oracle NoSQL Database for a copy of the license and
* additional information.
*/
package oracle.kv.impl.admin;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.logging.Level;
import java.util.logging.Logger;
import oracle.kv.impl.admin.plan.Plan;
import oracle.kv.impl.api.table.TableImpl;
import oracle.kv.impl.api.table.TableMetadata;
import oracle.kv.impl.metadata.Metadata;
import oracle.kv.impl.systables.SysTableDescriptor;
import oracle.kv.impl.systables.SysTableRegistry;
import com.sleepycat.je.utilint.StoppableThread;
/**
* A task that monitors system tables. It will create the tables if they don't
* exist and will upgrade existing tables if needed. This task should be run
* when the Admin becomes the master. If any action is taken (creating or
* evolving a table) the task will reschedule itself so that the actions can
* be retried in case they fail.
*
* This task is designed so it is not necessary to monitor plan failures. If
* the plan fails a new one will be created the next go around. An attempt is
* made to cancel plans that end in non-terminal state. However, if they are
* missed the plan pruning mechanism will eventually remove them.
*/
class SysTableMonitor extends StoppableThread {
private static final int THREAD_SOFT_SHUTDOWN_MS = 10000;
private final Admin admin;
/**
* Map of descriptors to plan IDs. The map is initialized to the
* set of table descriptors with the plan ID set to NO_PLAN. If the table
* needs attention the resulting plan ID is added. If no action is taken,
* the descriptor is removed. The task will retry (up to 10 times) as
* long as the map is not empty.
*/
private final Map descriptors;
/**
* Value in descriptors map to indicate there is no plan associated with
* the table.
*/
private static final int NO_PLAN = -1;
private int attempts = 0;
private volatile boolean isShutdown = false;
SysTableMonitor(Admin admin) {
super("System table monitor");
this.admin = admin;
descriptors = new HashMap<>(SysTableRegistry.descriptors.length);
for (SysTableDescriptor desc : SysTableRegistry.descriptors) {
descriptors.put(desc, NO_PLAN);
}
}
/**
* Checks to see if the system tables in the descriptors map are up to
* the correct version. If they are not, a plan is created to upgrade them.
*/
@Override
public void run() {
if (isShutdown) {
return;
}
getLogger().log(Level.INFO, "Starting {0}", this);
while (!isShutdown && !descriptors.isEmpty()) {
checkTables();
if (isShutdown || descriptors.isEmpty()) {
break;
}
attempts++;
if (attempts > 10) {
getLogger().log(Level.SEVERE,
"Failed to create or upgrade system " +
"tables after {0} attempts.", attempts);
break;
}
try {
Thread.sleep(10000);
} catch (InterruptedException ie) {
/* The sleep may be interrupted by shutdown */
if (!isShutdown) {
getLogger().log(Level.SEVERE,
"Unexpected exception in {0}: {1}",
new Object[]{this, ie});
}
break;
}
}
getLogger().log(Level.INFO, "Exit {0}", this);
}
private void checkTables() {
getLogger().log(Level.FINE, "Checking status of system tables");
final TableMetadata md = admin.getMetadata(TableMetadata.class,
Metadata.MetadataType.TABLE);
final Iterator> itr =
descriptors.entrySet().iterator();
while (!isShutdown && itr.hasNext()) {
final Entry entry = itr.next();
final SysTableDescriptor desc = entry.getKey();
int planId = entry.getValue();
/*
* If there is already a plan in place to handle this table, check
* on its state.
*/
if (planId != NO_PLAN) {
if (checkPlanState(planId, desc)) {
/* Plan succeeded, remove the descriptor */
itr.remove();
}
continue;
}
getLogger().log(Level.FINE,
"Checking status of system table {0}",
desc.getTableName());
/*
* If the table does not exist, or the metadata does not exist
* create the table (the plan will also create the metadata if
* needed).
*/
final TableImpl table =
(md == null) ? null : md.getTable(desc.getTableName());
if (table == null) {
final TableImpl newTable = desc.buildTable();
try {
planId = admin.getPlanner().
createAddTablePlan("Create system table",
newTable,
null,
true /* systemTable */);
admin.approvePlan(planId);
admin.executePlanOrFindMatch(planId);
descriptors.put(desc, planId);
} catch (Exception e) {
if (!isShutdown) {
getLogger().log(Level.INFO,
"Exception creating system" +
" table {0} {1}",
new Object[]{newTable.getName(),
e.getMessage()});
}
}
continue;
}
/*
* See if the table needs to be upgraded.
*/
final TableImpl newTable = desc.evolveTable(table, getLogger());
if (newTable != null) {
try {
planId = admin.getPlanner().
createEvolveTablePlan("Upgrade system table",
newTable.getInternalNamespace(),
newTable.getFullName(),
table.getTableVersion(),
newTable.getFieldMap(),
newTable.getDefaultTTL(),
newTable.getDescription(),
true /* systemTable */);
admin.approvePlan(planId);
admin.executePlanOrFindMatch(planId);
descriptors.put(desc, planId);
} catch (Exception e) {
if (!isShutdown) {
getLogger().log(Level.INFO,
"Exception evolving system" +
" table {0} {1}",
new Object[]{table.getName(),
e.getMessage()});
}
}
continue;
}
assert planId == NO_PLAN;
/* Nothing needed to be done, remove the descriptor. */
itr.remove();
}
}
/**
* Checks on the state of the plan handling the descriptor. Returns true
* if the plan has completed with success and its descriptor can be
* removed from the descriptors map.
*/
private boolean checkPlanState(int planId, SysTableDescriptor desc) {
final Plan plan = admin.getPlanById(planId);
/*
* In theory the plan could be pruned. In this case we don't know
* what state it ended in, so retry just in case.
*/
if (plan == null) {
getLogger().log(Level.FINE,
"Plan {0} for {1} is missing, retrying",
new Object[]{planId, desc});
descriptors.put(desc, NO_PLAN);
return false;
}
switch (plan.getState()) {
case PENDING:
case APPROVED:
case RUNNING:
/* Plan is still running. */
return false;
case SUCCEEDED:
getLogger().log(Level.FINE,
"Plan {0} for {1} completed",
new Object[]{planId, desc});
return true;
case INTERRUPTED:
case ERROR:
case INTERRUPT_REQUESTED:
/* Cancel old plan */
admin.cancelPlan(planId);
//$FALL-THROUGH$
case CANCELED:
/* Plan failed or was canceled. Retry. */
getLogger().log(Level.FINE,
"Plan {0} for {1} did not complete, retrying",
new Object[]{planId, desc});
descriptors.put(desc, NO_PLAN);
return false;
}
throw new IllegalStateException("Unknown plan state: " +
plan.getState());
}
@Override
protected int initiateSoftShutdown() {
isShutdown = true;
return THREAD_SOFT_SHUTDOWN_MS;
}
@Override
protected Logger getLogger() {
return admin.getLogger();
}
}
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