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/* This file is part of VoltDB.
* Copyright (C) 2008-2020 VoltDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with VoltDB. If not, see .
*/
package org.voltdb;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.json_voltpatches.JSONObject;
import org.voltcore.logging.VoltLogger;
import org.voltcore.messaging.BinaryPayloadMessage;
import org.voltcore.messaging.HostMessenger;
import org.voltcore.messaging.Mailbox;
import org.voltcore.messaging.VoltMessage;
import org.voltcore.network.Connection;
import org.voltcore.utils.CoreUtils;
import org.voltdb.client.ClientResponse;
import org.voltdb.messaging.LocalMailbox;
import org.voltdb.utils.CompressionService;
/**
* OpsAgent is a base class for providing non-blocking, non-transactional,
* potentially cluster-wide behavior, such as gathering statistics or other
* system information.
*/
// Izzy's ugh list:
// 1. Handle exceptions better, don't catch Throwable, etc
// 2. The well-known mailbox thing kinda sucks. Maybe add a higher-level
// dispatcher that can get the cluster nodes to create mailboxes for selectors
// and make them queryable by selector, to avoid having to keep adding
// well-known IDs for new services.
// 3. Handling of null/empty cases is bad.
public abstract class OpsAgent
{
protected static final VoltLogger hostLog = new VoltLogger("HOST");
private static final byte JSON_PAYLOAD = 0;
private static final byte OPS_PAYLOAD = 1;
private static final byte OPS_DUMMY = 2;
// ENG-5125
private static final int MAX_IN_FLIGHT_REQUESTS = 20;
static int OPS_COLLECTION_TIMEOUT = 60 * 1000;
private long m_nextRequestId = 0;
private Mailbox m_mailbox;
protected final String m_name;
private final ScheduledThreadPoolExecutor m_es;
//Just ack everything that passes through and don't do the work
//For startup this avoids initialization dependencies but allows
//new nodes to not block other agents on timeouts
private volatile boolean m_dummyMode;
protected HostMessenger m_messenger;
// Things that would be nice in the future:
// 1. Instead of the tables to be aggregates identified by index in the
// returned response, they should be named so it's safe if they return in
// any order.
// 2. Instead of guessing the number of returned tables, it would be nice
// if the selector mapped to something that specified the number of
// results, the call to get the stats, etc.
//
protected static class PendingOpsRequest {
//private final OpsSelector selector;
protected final String subselector;
protected final Connection c;
protected final long clientData;
private int expectedOpsResponses = 0;
protected VoltTable[] aggregateTables = null;
protected final long startTime;
private final JSONObject request;
Future timer;
public PendingOpsRequest(
OpsSelector selector,
String subselector,
Connection c,
long clientData,
long startTime,
JSONObject request) {
this.startTime = startTime;
//this.selector = selector;
this.subselector = subselector;
this.c = c;
this.clientData = clientData;
this.request = request;
}
@Override
public String toString() {
return "PendingOpsRequest [subselector=" + subselector + ", clientData=" + clientData
+ ", expectedOpsResponses=" + expectedOpsResponses + ", startTime=" + startTime + ", request="
+ request + "]";
}
}
private final Map m_pendingRequests = new HashMap();
public OpsAgent(String name) {
m_name = name;
m_es =
org.voltcore.utils.CoreUtils.getScheduledThreadPoolExecutor(m_name, 1, CoreUtils.SMALL_STACK_SIZE);
m_messenger = null;
}
/**
* Do the initial work associated with the OPS action. Subclasses will
* implement this bad boy and do whatever needs to be done. If distributed
* work is ultimately required, call distributeOpsWork() and return.
*/
abstract protected void collectStatsImpl(Connection c, long clientHandle, OpsSelector selector,
ParameterSet params) throws Exception;
/**
* For OPS actions which require distributed work, subclasses should
* override this method to perform whatever actions must be taken and
* return VoltTables suitable for aggregation at the initiating agent.
* Right now, the requirement is that the tables returned must be the
* identical count, be in identical order from all nodes, and have
* identical schema.
*/
abstract protected void handleJSONMessage(JSONObject obj) throws Exception;
/**
* For OPS actions generate a dummy response to the distributed
* work to avoid startup initialization dependencies. Startup can take
* a long time and we don't want to prevent other agents from making progress
*/
protected void handleJSONMessageAsDummy(JSONObject obj) throws Exception {
hostLog.info("Generating dummy response for ops request " + obj);
sendOpsResponse(null, obj, OPS_DUMMY);
}
/**
* Awkward interface. For OPS actions which may want to perform some final
* post-processing on the aggregated tables before the response is sent to
* the client, this will be called immediately before that send.
* Subclasses may make whatever changes they want to the response tables
* stored in the PendingOpsRequest at this time.
*/
protected void dispatchFinalAggregations(PendingOpsRequest request)
{
}
public void registerMailbox(final HostMessenger hostMessenger, final long hsId) {
m_messenger = hostMessenger;
hostMessenger.generateMailboxId(hsId);
m_mailbox = new LocalMailbox(hostMessenger, hsId) {
@Override
public void deliver(final VoltMessage message) {
m_es.submit(new Runnable() {
@Override
public void run() {
handleMailboxMessage(message);
}
});
}
};
hostMessenger.registerMailbox(m_mailbox);
}
private void handleMailboxMessage(VoltMessage message) {
try {
if (message instanceof BinaryPayloadMessage) {
BinaryPayloadMessage bpm = (BinaryPayloadMessage)message;
byte payload[] = CompressionService.decompressBytes(bpm.m_payload);
if (bpm.m_metadata[0] == JSON_PAYLOAD) {
String jsonString = new String(payload, "UTF-8");
JSONObject obj = new JSONObject(jsonString);
//In early startup generate dummy responses
if (m_dummyMode) {
handleJSONMessageAsDummy(obj);
} else {
handleJSONMessage(obj);
}
} else if (bpm.m_metadata[0] == OPS_PAYLOAD) {
handleOpsResponse(payload, false);
} else if (bpm.m_metadata[0] == OPS_DUMMY) {
handleOpsResponse(payload, true);
}
}
} catch (Exception e) {
hostLog.error("Exception processing message in OpsAgent for " + m_name + ": " + message, e);
} catch (Throwable t) {
//Handle throwable because otherwise the future swallows up other exceptions
VoltDB.crashLocalVoltDB("Exception processing message in OpsAgent for " + m_name + ": " + message, true, t);
}
}
private void handleOpsResponse(byte[] payload, boolean dummy) {
ByteBuffer buf = ByteBuffer.wrap(payload);
Long requestId = buf.getLong();
PendingOpsRequest request = m_pendingRequests.get(requestId);
if (request == null) {
hostLog.warn("Received an OPS response for OPS request " + requestId + " that no longer exists");
return;
}
// The first message we receive will create the correct number of tables. Nobody else better
// disagree or there will be trouble here in River City. Nobody else better add non-table
// stuff after the responses to the returned messages or said trouble will also occur. Ick, fragile.
if (request.aggregateTables == null && !dummy) {
List tables = new ArrayList();
while (buf.hasRemaining()) {
final int tableLength = buf.getInt();
int oldLimit = buf.limit();
buf.limit(buf.position() + tableLength);
ByteBuffer tableBuf = buf.slice();
buf.position(buf.limit()).limit(oldLimit);
ByteBuffer copy = ByteBuffer.allocate(tableBuf.capacity() * 2);
copy.put(tableBuf);
copy.limit(copy.position());
copy.position(0);
VoltTable vt = PrivateVoltTableFactory.createVoltTableFromBuffer( copy, false);
tables.add(vt);
}
request.aggregateTables = tables.toArray(new VoltTable[tables.size()]);
}
else if (!dummy) {
for (int ii = 0; ii < request.aggregateTables.length; ii++) {
if (buf.hasRemaining()) {
try {
final int tableLength = buf.getInt();
int oldLimit = buf.limit();
buf.limit(buf.position() + tableLength);
ByteBuffer tableBuf = buf.slice();
buf.position(buf.limit()).limit(oldLimit);
VoltTable vt = PrivateVoltTableFactory.createVoltTableFromBuffer(tableBuf, true);
request.aggregateTables[ii].addTable(vt);
} catch (Exception e) {
hostLog.error("Failed to merge table into index " + ii + " for request " + request, e);
request.timer.cancel(false);
m_pendingRequests.remove(requestId);
sendErrorResponse(request.c, ClientResponse.UNEXPECTED_FAILURE,
"Unexpected error occurred. Check logs for more details.", request.clientData);
return;
}
}
}
}
if (--request.expectedOpsResponses > 0) {
return;
}
request.timer.cancel(false);
m_pendingRequests.remove(requestId);
dispatchFinalAggregations(request);
sendClientResponse(request);
}
/**
* Perform the action associated with this agent, using the provided ParameterSet. This is the
* entry point to the OPS system.
*/
public void performOpsAction(final Connection c, final long clientHandle, final OpsSelector selector,
final ParameterSet params) throws Exception
{
m_es.submit(new Runnable() {
@Override
public void run() {
try {
collectStatsImpl(c, clientHandle, selector, params);
} catch (Exception e) {
hostLog.warn("Exception while attempting to collect stats", e);
// ENG-14639, prevent clients like sqlcmd from hanging on exception
sendErrorResponse(c, ClientResponse.OPERATIONAL_FAILURE,
"Failed to get statistics (" + e.getMessage() + ").",
clientHandle);
}
}
});
}
/**
* For OPS actions which run on every node, this method will distribute the
* necessary parameters to its peers on the other cluster nodes. Additionally, it will
* pre-check for excessive outstanding requests, and initialize the tracking and timeout of
* the new request. Subclasses of OpsAgent should use this when they need this service.
*/
protected void distributeOpsWork(PendingOpsRequest newRequest, JSONObject obj)
throws Exception
{
if (m_pendingRequests.size() > MAX_IN_FLIGHT_REQUESTS) {
/*
* Defensively check for an expired request not caught
* by timeout check. Should never happen.
*/
Iterator> iter = m_pendingRequests.entrySet().iterator();
final long now = System.currentTimeMillis();
boolean foundExpiredRequest = false;
while (iter.hasNext()) {
PendingOpsRequest por = iter.next().getValue();
if (now - por.startTime > OPS_COLLECTION_TIMEOUT * 2) {
iter.remove();
foundExpiredRequest = true;
}
}
if (!foundExpiredRequest) {
sendErrorResponse(newRequest.c, ClientResponse.GRACEFUL_FAILURE,
"Too many pending stat requests", newRequest.clientData);
return;
}
}
final long requestId = m_nextRequestId++;
m_pendingRequests.put(requestId, newRequest);
newRequest.timer = m_es.schedule(new Runnable() {
@Override
public void run() {
checkForRequestTimeout(requestId);
}
},
OPS_COLLECTION_TIMEOUT,
TimeUnit.MILLISECONDS);
// selector, subselector, interval filled in by parse...
obj.put("requestId", requestId);
obj.put("returnAddress", m_mailbox.getHSId());
int siteId = CoreUtils.getSiteIdFromHSId(m_mailbox.getHSId());
byte payloadBytes[] = CompressionService.compressBytes(obj.toString(4).getBytes("UTF-8"));
for (int hostId : m_messenger.getLiveHostIds()) {
long agentHsId = CoreUtils.getHSIdFromHostAndSite(hostId, siteId);
newRequest.expectedOpsResponses++;
BinaryPayloadMessage bpm = new BinaryPayloadMessage(new byte[] {JSON_PAYLOAD}, payloadBytes);
m_mailbox.send(agentHsId, bpm);
}
}
private void checkForRequestTimeout(long requestId) {
PendingOpsRequest por = m_pendingRequests.remove(requestId);
if (por == null) {
return;
}
String request = "Exception formatting request JSON";
try {
request = por.request.toString(4);
} catch (Throwable t) {}
hostLog.warn("OPS request for " + m_name + ", " + requestId +
" timed out, sending error to client. Request:" + request);
sendErrorResponse(por.c, ClientResponse.GRACEFUL_FAILURE,
"OPS request hit sixty second timeout before all responses were received",
por.clientData);
}
/**
* Send the final response stored in the PendingOpsRequest to the client which initiated the
* action. Will be called automagically after aggregating cluster-wide responses, but may
* be called directly by subclasses if necessary.
*/
protected void sendClientResponse(PendingOpsRequest request) {
byte statusCode = ClientResponse.SUCCESS;
String statusString = null;
/*
* It is possible not to receive a table response if a feature is not enabled
*/
// All of the null/empty table handling/detecting/generation sucks. Just making it
// work for now, not making it pretty. --izzy
VoltTable responseTables[] = request.aggregateTables;
if (responseTables == null || responseTables.length == 0) {
responseTables = new VoltTable[0];
statusCode = ClientResponse.GRACEFUL_FAILURE;
statusString =
"Requested info \"" + request.subselector +
"\" is not yet available or not supported in the current configuration.";
}
ClientResponseImpl response =
new ClientResponseImpl(statusCode, ClientResponse.UNINITIALIZED_APP_STATUS_CODE, null,
responseTables, statusString);
response.setClientHandle(request.clientData);
ByteBuffer buf = ByteBuffer.allocate(response.getSerializedSize() + 4);
buf.putInt(buf.capacity() - 4);
response.flattenToBuffer(buf).flip();
request.c.writeStream().enqueue(buf);
}
protected void sendOpsResponse(VoltTable[] results, JSONObject obj) throws Exception {
sendOpsResponse(results, obj, OPS_PAYLOAD);
}
/**
* Return the results of distributed work to the original requesting agent.
* Used by subclasses to respond after they've done their local work.
*/
private void sendOpsResponse(VoltTable[] results, JSONObject obj, byte payloadType) throws Exception
{
long requestId = obj.getLong("requestId");
long returnAddress = obj.getLong("returnAddress");
// Send a response with no data since the stats is not supported or not yet available
if (results == null) {
ByteBuffer responseBuffer = ByteBuffer.allocate(8);
responseBuffer.putLong(requestId);
byte responseBytes[] = CompressionService.compressBytes(responseBuffer.array());
BinaryPayloadMessage bpm = new BinaryPayloadMessage( new byte[] {payloadType}, responseBytes);
m_mailbox.send(returnAddress, bpm);
return;
}
ByteBuffer[] bufs = new ByteBuffer[results.length];
int statbytes = 0;
for (int i = 0; i < results.length; i++) {
bufs[i] = results[i].getBuffer();
bufs[i].position(0);
statbytes += bufs[i].remaining();
}
ByteBuffer responseBuffer = ByteBuffer.allocate(
8 + // requestId
4 * results.length + // length prefix for each stats table
+ statbytes);
responseBuffer.putLong(requestId);
for (ByteBuffer buf : bufs) {
responseBuffer.putInt(buf.remaining());
responseBuffer.put(buf);
}
byte responseBytes[] = CompressionService.compressBytes(responseBuffer.array());
BinaryPayloadMessage bpm = new BinaryPayloadMessage( new byte[] {payloadType}, responseBytes);
m_mailbox.send(returnAddress, bpm);
}
public void shutdown() throws InterruptedException {
m_es.shutdown();
m_es.awaitTermination(1, TimeUnit.DAYS);
}
protected void sendErrorResponse(Connection c, byte status, String reason, long handle)
{
ClientResponseImpl errorResponse = new ClientResponseImpl(status, new VoltTable[0], reason, handle);
ByteBuffer buf = ByteBuffer.allocate(errorResponse.getSerializedSize() + 4);
buf.putInt(buf.capacity() - 4);
errorResponse.flattenToBuffer(buf).flip();
c.writeStream().enqueue(buf);
return;
}
public void setDummyMode(boolean enabled) {
m_dummyMode = enabled;
}
}
