Examples with PartitionAccessor com.linkedin.d2.balancer.util.partitions.PartitionAccessor used on opensource projects

Example 1 with PartitionAccessor

use of com.linkedin.d2.balancer.util.partitions.PartitionAccessor in project rest.li by linkedin.

the class SimpleLoadBalancer method chooseTrackerClient.

private TrackerClient chooseTrackerClient(Request request, RequestContext requestContext, String serviceName, String clusterName, ClusterProperties cluster, LoadBalancerStateItem<UriProperties> uriItem, UriProperties uris, List<LoadBalancerState.SchemeStrategyPair> orderedStrategies, ServiceProperties serviceProperties) throws ServiceUnavailableException {
    // now try and find a tracker client for the uri
    TrackerClient trackerClient = null;
    URI targetHost = KeyMapper.TargetHostHints.getRequestContextTargetHost(requestContext);
    int partitionId = -1;
    URI requestUri = request.getURI();
    if (targetHost == null) {
        PartitionAccessor accessor = getPartitionAccessor(serviceName, clusterName);
        try {
            partitionId = accessor.getPartitionId(requestUri);
        } catch (PartitionAccessException e) {
            die(serviceName, "Error in finding the partition for URI: " + requestUri + ", " + e.getMessage());
        }
    } else {
        // This is the case of scatter/gather or search, where the target host may be chosen to be responsible for
        // more than one partitions (The target host was picked from a consistent hash ring, so load balancing is already in effect).
        // we randomly pick one partition to check for the call dropping
        // This is done for two reasons:
        // 1. Currently there is no way to know for which subset of partitions the target host is chosen for
        //    if it is serving more than one partitions. This can be added, but it requires the change of public interfaces (KeyMapper) so that
        //    more hints can be added to the request context for the concerned the partitions
        // 2. More importantly, there is no good way to check for call dropping even if the above problem is solved.
        //    For example, if a target host is chosen for partition 1, 5, 7, with call drop rates of 0, 0.2, 0.4 respectively
        //    A reasonable way to proceed would be use the highest drop rate and do the check once for the target host,
        //    but currently the check can only be done for each partition and only with boolean result (no access to drop rate)
        // The partition to check is picked at random to be conservative.
        // E.g. in the above example, we don't want to always use the drop rate of partition 1.
        Map<Integer, PartitionData> partitionDataMap = uris.getPartitionDataMap(targetHost);
        if (partitionDataMap == null || partitionDataMap.isEmpty()) {
            die(serviceName, "There is no partition data for server host: " + targetHost + ". URI: " + requestUri);
        }
        Set<Integer> partitions = partitionDataMap.keySet();
        Iterator<Integer> iterator = partitions.iterator();
        int index = _random.nextInt(partitions.size());
        for (int i = 0; i <= index; i++) {
            partitionId = iterator.next();
        }
    }
    List<TrackerClient> clientsToLoadBalance = null;
    for (LoadBalancerState.SchemeStrategyPair pair : orderedStrategies) {
        LoadBalancerStrategy strategy = pair.getStrategy();
        String scheme = pair.getScheme();
        clientsToLoadBalance = getPotentialClients(serviceName, serviceProperties, uris, scheme, partitionId);
        trackerClient = strategy.getTrackerClient(request, requestContext, uriItem.getVersion(), partitionId, clientsToLoadBalance);
        debug(_log, "load balancer strategy for ", serviceName, " returned: ", trackerClient);
        // break as soon as we find an available cluster client
        if (trackerClient != null) {
            break;
        }
    }
    if (trackerClient == null) {
        if (clientsToLoadBalance == null || clientsToLoadBalance.isEmpty()) {
            die(serviceName, "Service: " + serviceName + " unable to find a host to route the request" + " in partition: " + partitionId + " cluster: " + clusterName + ". Check what cluster your servers are announcing to.");
        } else {
            die(serviceName, "Service: " + serviceName + " is in a bad state (high latency/high error). " + "Dropping request. Cluster: " + clusterName + ", partitionId:" + partitionId + " (" + clientsToLoadBalance.size() + " hosts)");
        }
    }
    return trackerClient;
}

Example 2 with PartitionAccessor

use of com.linkedin.d2.balancer.util.partitions.PartitionAccessor in project rest.li by linkedin.

the class SimpleLoadBalancer method getPartitionInformation.

/**
   * If given a collection of keys, the method will maps keys to partitions and
   * return the servers that belongs to that partition up to limitHostPerPartition.
   *
   * If no keys are specified, the method will return hosts in all partitions
   *
   * @param serviceUri for example d2://articles
   * @param keys all the keys we want to find the partition for
   * @param limitHostPerPartition the number of hosts that we should return for this partition. Must be larger than 0.
   * @param hash this will be used to create Iterator for the hosts in the hash ring
   * @return Number of hosts in requested partitions. See {@link com.linkedin.d2.balancer.util.HostToKeyMapper} for more details.
   * @throws ServiceUnavailableException
   */
@Override
public <K> HostToKeyMapper<K> getPartitionInformation(URI serviceUri, Collection<K> keys, int limitHostPerPartition, int hash) throws ServiceUnavailableException {
    if (limitHostPerPartition <= 0) {
        throw new IllegalArgumentException("limitHostPartition cannot be 0 or less");
    }
    ServiceProperties service = listenToServiceAndCluster(serviceUri);
    String serviceName = service.getServiceName();
    String clusterName = service.getClusterName();
    ClusterProperties cluster = getClusterProperties(serviceName, clusterName);
    LoadBalancerStateItem<UriProperties> uriItem = getUriItem(serviceName, clusterName, cluster);
    UriProperties uris = uriItem.getProperty();
    List<LoadBalancerState.SchemeStrategyPair> orderedStrategies = _state.getStrategiesForService(serviceName, service.getPrioritizedSchemes());
    Map<Integer, Integer> partitionWithoutEnoughHost = new HashMap<Integer, Integer>();
    if (!orderedStrategies.isEmpty()) {
        // get the partitionId -> keys mapping
        final PartitionAccessor accessor = getPartitionAccessor(serviceName, clusterName);
        int maxPartitionId = accessor.getMaxPartitionId();
        List<K> unmappedKeys = new ArrayList<K>();
        Map<Integer, Set<K>> partitionSet = getPartitionSet(keys, accessor, unmappedKeys);
        final LoadBalancerState.SchemeStrategyPair pair = orderedStrategies.get(0);
        //get the partitionId -> host URIs list
        Map<Integer, KeysAndHosts<K>> partitionDataMap = new HashMap<Integer, KeysAndHosts<K>>();
        for (Integer partitionId : partitionSet.keySet()) {
            Set<URI> possibleUris = uris.getUriBySchemeAndPartition(pair.getScheme(), partitionId);
            List<TrackerClient> trackerClients = getPotentialClients(serviceName, service, possibleUris);
            int size = trackerClients.size() <= limitHostPerPartition ? trackerClients.size() : limitHostPerPartition;
            List<URI> rankedUri = new ArrayList<URI>(size);
            Ring<URI> ring = pair.getStrategy().getRing(uriItem.getVersion(), partitionId, trackerClients);
            Iterator<URI> iterator = ring.getIterator(hash);
            while (iterator.hasNext() && rankedUri.size() < size) {
                URI uri = iterator.next();
                if (!rankedUri.contains(uri)) {
                    rankedUri.add(uri);
                }
            }
            if (rankedUri.size() < limitHostPerPartition) {
                partitionWithoutEnoughHost.put(partitionId, limitHostPerPartition - rankedUri.size());
            }
            KeysAndHosts<K> keysAndHosts = new KeysAndHosts<K>(partitionSet.get(partitionId), rankedUri);
            partitionDataMap.put(partitionId, keysAndHosts);
        }
        return new HostToKeyMapper<K>(unmappedKeys, partitionDataMap, limitHostPerPartition, maxPartitionId + 1, partitionWithoutEnoughHost);
    } else {
        throw new ServiceUnavailableException(serviceName, "Unable to find a load balancer strategy");
    }
}

Example 3 with PartitionAccessor

use of com.linkedin.d2.balancer.util.partitions.PartitionAccessor in project rest.li by linkedin.

the class SimpleLoadBalancer method getRings.

@Override
public <K> MapKeyResult<Ring<URI>, K> getRings(URI serviceUri, Iterable<K> keys) throws ServiceUnavailableException {
    ServiceProperties service = listenToServiceAndCluster(serviceUri);
    String serviceName = service.getServiceName();
    String clusterName = service.getClusterName();
    ClusterProperties cluster = getClusterProperties(serviceName, clusterName);
    LoadBalancerStateItem<UriProperties> uriItem = getUriItem(serviceName, clusterName, cluster);
    UriProperties uris = uriItem.getProperty();
    List<LoadBalancerState.SchemeStrategyPair> orderedStrategies = _state.getStrategiesForService(serviceName, service.getPrioritizedSchemes());
    if (!orderedStrategies.isEmpty()) {
        LoadBalancerState.SchemeStrategyPair pair = orderedStrategies.get(0);
        PartitionAccessor accessor = getPartitionAccessor(serviceName, clusterName);
        // first distribute keys to partitions
        Map<Integer, Set<K>> partitionSet = new HashMap<Integer, Set<K>>();
        List<MapKeyResult.UnmappedKey<K>> unmappedKeys = new ArrayList<MapKeyResult.UnmappedKey<K>>();
        for (final K key : keys) {
            int partitionId;
            try {
                partitionId = accessor.getPartitionId(key.toString());
            } catch (PartitionAccessException e) {
                unmappedKeys.add(new MapKeyResult.UnmappedKey<K>(key, MapKeyResult.ErrorType.FAIL_TO_FIND_PARTITION));
                continue;
            }
            Set<K> set = partitionSet.get(partitionId);
            if (set == null) {
                set = new HashSet<K>();
                partitionSet.put(partitionId, set);
            }
            set.add(key);
        }
        // then we find the ring for each partition and create a map of Ring<URI> to Set<K>
        final Map<Ring<URI>, Collection<K>> ringMap = new IdentityHashMap<Ring<URI>, Collection<K>>(partitionSet.size() * 2);
        for (Map.Entry<Integer, Set<K>> entry : partitionSet.entrySet()) {
            int partitionId = entry.getKey();
            List<TrackerClient> clients = getPotentialClients(serviceName, service, uris, pair.getScheme(), partitionId);
            Ring<URI> ring = pair.getStrategy().getRing(uriItem.getVersion(), partitionId, clients);
            // make sure the same ring is not used in other partition
            Object oldValue = ringMap.put(ring, entry.getValue());
            assert (oldValue == null);
        }
        return new MapKeyResult<Ring<URI>, K>(ringMap, unmappedKeys);
    } else {
        throw new ServiceUnavailableException(serviceName, "Unable to find a load balancer strategy");
    }
}

Example 4 with PartitionAccessor

use of com.linkedin.d2.balancer.util.partitions.PartitionAccessor in project rest.li by linkedin.

the class RetryClientTest method prepareLoadBalancer.

public SimpleLoadBalancer prepareLoadBalancer(List<String> uris) throws URISyntaxException {
    String serviceName = "retryService";
    String clusterName = "cluster";
    String path = "";
    String strategyName = "degrader";
    // setup partition
    Map<URI, Map<Integer, PartitionData>> partitionDescriptions = new HashMap<URI, Map<Integer, PartitionData>>();
    for (String uri : uris) {
        final URI foo = URI.create(uri);
        Map<Integer, PartitionData> foo1Data = new HashMap<Integer, PartitionData>();
        foo1Data.put(0, new PartitionData(1.0));
        partitionDescriptions.put(foo, foo1Data);
    }
    DegraderLoadBalancerStrategyV3 strategy = new DegraderLoadBalancerStrategyV3(new DegraderLoadBalancerStrategyConfig(5000), serviceName, null);
    List<LoadBalancerState.SchemeStrategyPair> orderedStrategies = new ArrayList<LoadBalancerState.SchemeStrategyPair>();
    orderedStrategies.add(new LoadBalancerState.SchemeStrategyPair("http", strategy));
    PartitionAccessor accessor = new TestRetryPartitionAccessor();
    SimpleLoadBalancer balancer = new SimpleLoadBalancer(new PartitionedLoadBalancerTestState(clusterName, serviceName, path, strategyName, partitionDescriptions, orderedStrategies, accessor));
    return balancer;
}

Example 5 with PartitionAccessor

use of com.linkedin.d2.balancer.util.partitions.PartitionAccessor in project rest.li by linkedin.

the class SimpleLoadBalancerTest method testGetPartitionInfoOrdering.

/**
   * This tests the getPartitionInfo() when given a collection of keys (actually a test for KeyMapper.mapKeysV3()).
   */
@Test
public void testGetPartitionInfoOrdering() throws Exception {
    String serviceName = "articles";
    String clusterName = "cluster";
    String path = "path";
    String strategyName = "degrader";
    // setup 3 partitions. Partition 1 and Partition 2 both have server1 - server3. Partition 3 only has server1.
    Map<URI, Map<Integer, PartitionData>> partitionDescriptions = new HashMap<URI, Map<Integer, PartitionData>>();
    final URI server1 = new URI("http://foo1.com");
    Map<Integer, PartitionData> server1Data = new HashMap<Integer, PartitionData>();
    server1Data.put(1, new PartitionData(1.0));
    server1Data.put(2, new PartitionData(1.0));
    server1Data.put(3, new PartitionData(1.0));
    partitionDescriptions.put(server1, server1Data);
    final URI server2 = new URI("http://foo2.com");
    Map<Integer, PartitionData> server2Data = new HashMap<Integer, PartitionData>();
    server2Data.put(1, new PartitionData(1.0));
    server2Data.put(2, new PartitionData(1.0));
    partitionDescriptions.put(server2, server2Data);
    final URI server3 = new URI("http://foo3.com");
    Map<Integer, PartitionData> server3Data = new HashMap<Integer, PartitionData>();
    server3Data.put(1, new PartitionData(1.0));
    server3Data.put(2, new PartitionData(1.0));
    partitionDescriptions.put(server3, server3Data);
    //setup strategy which involves tweaking the hash ring to get partitionId -> URI host
    List<LoadBalancerState.SchemeStrategyPair> orderedStrategies = new ArrayList<LoadBalancerState.SchemeStrategyPair>();
    LoadBalancerStrategy strategy = new TestLoadBalancerStrategy(partitionDescriptions);
    orderedStrategies.add(new LoadBalancerState.SchemeStrategyPair("http", strategy));
    //setup the partition accessor which can only map keys from 1 - 3.
    PartitionAccessor accessor = new TestPartitionAccessor();
    URI serviceURI = new URI("d2://" + serviceName);
    SimpleLoadBalancer balancer = new SimpleLoadBalancer(new PartitionedLoadBalancerTestState(clusterName, serviceName, path, strategyName, partitionDescriptions, orderedStrategies, accessor));
    List<Integer> keys = new ArrayList<Integer>();
    keys.add(1);
    keys.add(2);
    keys.add(3);
    keys.add(123);
    HostToKeyMapper<Integer> result = balancer.getPartitionInformation(serviceURI, keys, 3, 123);
    Assert.assertEquals(result.getLimitHostPerPartition(), 3);
    Assert.assertEquals(1, result.getUnmappedKeys().size());
    Assert.assertEquals(123, (int) result.getUnmappedKeys().iterator().next().getKey());
    //partition 0 should be null
    Assert.assertNull(result.getPartitionInfoMap().get(0));
    // results for partition 1 should contain server1, server2 and server3
    KeysAndHosts<Integer> keysAndHosts1 = result.getPartitionInfoMap().get(1);
    Assert.assertTrue(keysAndHosts1.getKeys().size() == 1);
    Assert.assertTrue(keysAndHosts1.getKeys().iterator().next() == 1);
    List<URI> ordering1 = keysAndHosts1.getHosts();
    // results for partition 2 should be the same as partition1.
    KeysAndHosts<Integer> keysAndHosts2 = result.getPartitionInfoMap().get(2);
    Assert.assertTrue(keysAndHosts2.getKeys().size() == 1);
    Assert.assertTrue(keysAndHosts2.getKeys().iterator().next() == 2);
    List<URI> ordering2 = keysAndHosts2.getHosts();
    //for partition 3
    KeysAndHosts<Integer> keysAndHosts3 = result.getPartitionInfoMap().get(3);
    Assert.assertTrue(keysAndHosts3.getKeys().size() == 1);
    Assert.assertTrue(keysAndHosts3.getKeys().iterator().next() == 3);
    List<URI> ordering3 = keysAndHosts3.getHosts();
    // Just compare the size and contents of the list, not the ordering.
    Assert.assertTrue(ordering1.size() == 3);
    List<URI> allServers = new ArrayList<>();
    allServers.add(server1);
    allServers.add(server2);
    allServers.add(server3);
    Assert.assertTrue(ordering1.containsAll(allServers));
    Assert.assertTrue(ordering2.containsAll(allServers));
    Assert.assertEquals(ordering1, ordering2);
    Assert.assertEquals(ordering3.get(0), server1);
    Assert.assertTrue(result.getPartitionsWithoutEnoughHosts().containsKey(3));
    Assert.assertEquals((int) result.getPartitionsWithoutEnoughHosts().get(3), 2);
}