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Building blocks for ClusterMate-based services and servers.
package com.fasterxml.clustermate.service.servlet;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicReference;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.ObjectWriter;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.storemate.backend.bdbje.BDBBackendStats;
import com.fasterxml.storemate.shared.TimeMaster;
import com.fasterxml.storemate.store.StorableStore;
import com.fasterxml.storemate.store.backend.BackendStats;
import com.fasterxml.storemate.store.backend.BackendStatsConfig;
import com.fasterxml.storemate.store.backend.StoreBackend;
import com.fasterxml.clustermate.service.*;
import com.fasterxml.clustermate.service.metrics.AllOperationMetrics;
import com.fasterxml.clustermate.service.metrics.BackendMetrics;
import com.fasterxml.clustermate.service.metrics.ExternalMetrics;
import com.sleepycat.je.EnvironmentStats;
/**
* Stand-alone servlet that may be used for serving metrics information
* regarding this node (and possibly its peers as well)
*/
@SuppressWarnings("serial")
public class NodeMetricsServlet extends ServletBase
{
/**
* Query parameter to request server to refresh its stats
*/
protected final static String QUERY_PARAM_REFRESH = "refresh";
/**
* Query parameter to further request server to obtain full
* statistics, not just cheap ones.
*/
protected final static String QUERY_PARAM_FULL = "full";
// Only probe for metrics once every 5 minutes
protected final static long UPDATE_PERIOD_MSECS = 5L * 60 * 1000;
// let's only collect what can be gathered fast; not reset stats
protected final static BackendStatsConfig BACKEND_STATS_CONFIG
= BackendStatsConfig.DEFAULT
.onlyCollectFast(true)
.resetStatsAfterCollection(false);
protected final ObjectWriter _jsonWriter;
protected final StorableStore _entryStore;
protected final AllOperationMetrics.Provider _operationMetrics;
protected final LastAccessStore _lastAccessStore;
protected final TimeMaster _timeMaster;
protected final AtomicReference _cachedMetrics
= new AtomicReference();
/*
/**********************************************************************
/* Life-cycle
/**********************************************************************
*/
public NodeMetricsServlet(SharedServiceStuff stuff, Stores stores,
AllOperationMetrics.Provider opMetrics)
{
// null -> use servlet path base as-is
super(null, null);
_timeMaster = stuff.getTimeMaster();
// for robustness, allow empty beans...
/* 16-May-2013, tatu: Need to use separate mapper just because
* our default inclusion mechanism may differ...
*/
ObjectMapper mapper = new ObjectMapper();
/* Looks like NON_DEFAULT can not be used, just because not all
* classes can be instantiated. So for now need to use NON_EMPTY...
*/
mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);
_jsonWriter = mapper.writerWithType(ExternalMetrics.class)
.without(SerializationFeature.FAIL_ON_EMPTY_BEANS);
_entryStore = stores.getEntryStore();
_lastAccessStore = stores.getLastAccessStore();
_operationMetrics = opMetrics;
}
/*
/**********************************************************************
/* End points: for now just GET
/**********************************************************************
*/
/**
* GET is used for simple access of cluster status
*/
@Override
public void handleGet(ServletServiceRequest request, ServletServiceResponse response,
OperationDiagnostics metadata) throws IOException
{
try {
// One more thing: is caller trying to force refresh?
boolean forceRefresh = "true".equals(request.getQueryParameter(QUERY_PARAM_REFRESH));
boolean full = "true".equals(request.getQueryParameter(QUERY_PARAM_FULL));
SerializedMetrics ser = _cachedMetrics.get();
long now = _timeMaster.currentTimeMillis();
if (ser == null || forceRefresh || now >= ser.cacheUntil) {
ExternalMetrics metrics = _gatherMetrics(now, full);
byte[] raw;
raw = _jsonWriter
// for diagnostics:
.withDefaultPrettyPrinter()
.writeValueAsBytes(metrics);
ser = new SerializedMetrics(now + UPDATE_PERIOD_MSECS, raw);
_cachedMetrics.set(ser);
}
response = (ServletServiceResponse) response.ok()
.setContentTypeJson();
response.writeRaw(ser.serialized);
} catch (Exception e) {
String msg = "Failed to serialize Metrics: "+e;
LOG.warn(msg, e);
response = (ServletServiceResponse) response
.internalError(msg)
.setContentTypeText()
;
response.writeOut(_jsonWriter);
}
}
/*
/**********************************************************************
/* Internal methods
/**********************************************************************
*/
protected ExternalMetrics _gatherMetrics(long creationTime, boolean fullStats)
{
ExternalMetrics metrics = new ExternalMetrics(creationTime);
StoreBackend entries = _entryStore.getBackend();
BackendStatsConfig conf = BACKEND_STATS_CONFIG;
if (fullStats) {
conf = conf.onlyCollectFast(false);
}
metrics.stores.entries = new BackendMetrics(creationTime,
entries.getEntryCount(),
_clean(entries.getEntryStatistics(BACKEND_STATS_CONFIG)));
metrics.stores.entryIndex = new BackendMetrics(creationTime,
entries.getIndexedCount(),
_clean(entries.getIndexStatistics(BACKEND_STATS_CONFIG)));
metrics.stores.lastAccessStore = new BackendMetrics(creationTime,
_lastAccessStore.getEntryCount(),
_clean(_lastAccessStore.getEntryStatistics(BACKEND_STATS_CONFIG)));
metrics.operations = _operationMetrics.getOperationMetrics();
return metrics;
}
protected BackendStats _clean(BackendStats stats)
{
// Nasty back-dep, but has to do for now...
if (stats instanceof BDBBackendStats) {
return new CleanBDBStats((BDBBackendStats) stats);
}
return stats;
}
/*
/**********************************************************************
/* Helper class(es)
/**********************************************************************
*/
/**
* Helper class we only need for filtering out some unwanted
* properties.
*/
static class CleanBDBStats
extends BDBBackendStats
{
// this is an alternative to mix-ins, which would also work
@JsonIgnoreProperties({ "tips", "statGroups" })
public EnvironmentStats getEnv() {
return env;
}
public CleanBDBStats(BDBBackendStats raw)
{
super();
db = raw.db;
env = raw.env;
}
}
private final static class SerializedMetrics
{
public final long cacheUntil;
public final byte[] serialized;
public SerializedMetrics(long expiration, byte[] data) {
cacheUntil = expiration;
serialized = data;
}
}
}