(ndp) Fix process tracking in domain discovery process

This is a working "work in progress" commit, will need more refinement, but given the usual difficulties in testing crawler-adjacent code without actually crawling, it needs some maturation time in production.

code/common/db/resources/db/migration/V25_06_0_005__ndp__new_domains_queue.sql

@@ -0,0 +1,12 @@
+-- Table holding domains to be processed by the NDP in order to figure out whether to add them to
+-- be crawled.
+
+CREATE TABLE IF NOT EXISTS NDP_NEW_DOMAINS(
+    DOMAIN_ID INT NOT NULL PRIMARY KEY,
+    STATE ENUM ('NEW', 'ACCEPTED', 'REJECTED') NOT NULL DEFAULT 'NEW',
+    PRIORITY INT NOT NULL DEFAULT 0,
+    TS_CHANGE TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
+    CHECK_COUNT INT NOT NULL DEFAULT 0
+);
+
+CREATE INDEX IF NOT EXISTS NDP_NEW_DOMAINS__STATE_PRIORITY ON NDP_NEW_DOMAINS (STATE, PRIORITY DESC);

code/execution/build.gradle

@@ -20,6 +20,7 @@ dependencies {
     implementation project(':code:processes:live-crawling-process')
     implementation project(':code:processes:loading-process')
     implementation project(':code:processes:ping-process')
+    implementation project(':code:processes:new-domain-process')
     implementation project(':code:processes:converting-process')
     implementation project(':code:processes:index-constructor-process')
 
@@ -41,7 +42,6 @@ dependencies {
     implementation project(':code:functions:nsfw-domain-filter')
     implementation project(':code:execution:api')
 
-    implementation project(':code:processes:crawling-process:model')
     implementation project(':code:processes:crawling-process:model')
     implementation project(':code:processes:crawling-process:ft-link-parser')
     implementation project(':code:index:index-journal')

code/execution/java/nu/marginalia/actor/ExecutorActor.java

@@ -14,6 +14,7 @@ public enum ExecutorActor {
     PROC_CRAWLER_SPAWNER(NodeProfile.BATCH_CRAWL, NodeProfile.MIXED),
     PROC_PING_SPAWNER(NodeProfile.BATCH_CRAWL, NodeProfile.MIXED, NodeProfile.REALTIME),
     PROC_EXPORT_TASKS_SPAWNER(NodeProfile.BATCH_CRAWL, NodeProfile.MIXED),
+    PROC_NDP_SPAWNER(NodeProfile.MIXED, NodeProfile.REALTIME),
     ADJACENCY_CALCULATION(NodeProfile.BATCH_CRAWL, NodeProfile.MIXED),
     EXPORT_DATA(NodeProfile.BATCH_CRAWL, NodeProfile.MIXED),
     EXPORT_SEGMENTATION_MODEL(NodeProfile.BATCH_CRAWL, NodeProfile.MIXED),

code/execution/java/nu/marginalia/actor/ExecutorActorControlService.java

@@ -49,6 +49,7 @@ public class ExecutorActorControlService {
                                        RecrawlSingleDomainActor recrawlSingleDomainActor,
                                        RestoreBackupActor restoreBackupActor,
                                        ConverterMonitorActor converterMonitorFSM,
+                                       NdpMonitorActor ndpMonitorActor,
                                        PingMonitorActor pingMonitorActor,
                                        CrawlerMonitorActor crawlerMonitorActor,
                                        LiveCrawlerMonitorActor liveCrawlerMonitorActor,
@@ -93,7 +94,7 @@ public class ExecutorActorControlService {
         register(ExecutorActor.PROC_PING_SPAWNER, pingMonitorActor);
         register(ExecutorActor.PROC_LIVE_CRAWL_SPAWNER, liveCrawlerMonitorActor);
         register(ExecutorActor.PROC_EXPORT_TASKS_SPAWNER, exportTasksMonitorActor);
-
+        register(ExecutorActor.PROC_NDP_SPAWNER, ndpMonitorActor);
         register(ExecutorActor.MONITOR_PROCESS_LIVENESS, processMonitorFSM);
         register(ExecutorActor.MONITOR_FILE_STORAGE, fileStorageMonitorActor);
 

code/execution/java/nu/marginalia/actor/proc/NdpMonitorActor.java

@@ -0,0 +1,29 @@
+package nu.marginalia.actor.proc;
+
+import com.google.gson.Gson;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+import nu.marginalia.actor.monitor.AbstractProcessSpawnerActor;
+import nu.marginalia.mq.persistence.MqPersistence;
+import nu.marginalia.mqapi.ProcessInboxNames;
+import nu.marginalia.process.ProcessService;
+import nu.marginalia.service.module.ServiceConfiguration;
+
+@Singleton
+public class NdpMonitorActor extends AbstractProcessSpawnerActor {
+
+    @Inject
+    public NdpMonitorActor(Gson gson,
+                                   ServiceConfiguration configuration,
+                                   MqPersistence persistence,
+                                   ProcessService processService) {
+        super(gson,
+                configuration,
+                persistence,
+                processService,
+                ProcessInboxNames.NDP_INBOX,
+                ProcessService.ProcessId.NDP);
+    }
+
+
+}

code/execution/java/nu/marginalia/process/ProcessService.java

@@ -8,6 +8,7 @@ import nu.marginalia.crawl.CrawlerMain;
 import nu.marginalia.index.IndexConstructorMain;
 import nu.marginalia.livecrawler.LiveCrawlerMain;
 import nu.marginalia.loading.LoaderMain;
+import nu.marginalia.ndp.NdpMain;
 import nu.marginalia.ping.PingMain;
 import nu.marginalia.service.control.ServiceEventLog;
 import nu.marginalia.service.server.BaseServiceParams;
@@ -57,6 +58,7 @@ public class ProcessService {
         CONVERTER(ConverterMain.class),
         LOADER(LoaderMain.class),
         INDEX_CONSTRUCTOR(IndexConstructorMain.class),
+        NDP(NdpMain.class),
         EXPORT_TASKS(ExportTasksMain.class),
         ;
 
@@ -72,6 +74,7 @@ public class ProcessService {
                 case CONVERTER -> "CONVERTER_PROCESS_OPTS";
                 case LOADER -> "LOADER_PROCESS_OPTS";
                 case PING -> "PING_PROCESS_OPTS";
+                case NDP -> "NDP_PROCESS_OPTS";
                 case INDEX_CONSTRUCTOR -> "INDEX_CONSTRUCTION_PROCESS_OPTS";
                 case EXPORT_TASKS -> "EXPORT_TASKS_PROCESS_OPTS";
             };

code/processes/new-domain-process/build.gradle

@@ -0,0 +1,73 @@
+plugins {
+    id 'java'
+
+    id 'application'
+    id 'jvm-test-suite'
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(rootProject.ext.jvmVersion))
+    }
+}
+
+application {
+    mainClass = 'nu.marginalia.ping.PingMain'
+    applicationName = 'ping-process'
+}
+
+tasks.distZip.enabled = false
+
+apply from: "$rootProject.projectDir/srcsets.gradle"
+
+dependencies {
+
+    implementation project(':code:common:db')
+    implementation project(':code:common:model')
+    implementation project(':code:common:config')
+    implementation project(':code:common:service')
+
+    implementation project(':code:libraries:domain-lock')
+    implementation project(':code:libraries:geo-ip')
+    implementation project(':code:libraries:message-queue')
+    implementation project(':code:libraries:blocking-thread-pool')
+
+    implementation project(':code:processes:process-mq-api')
+    implementation project(':code:processes:crawling-process:ft-content-type')
+    implementation project(':code:processes:crawling-process:ft-link-parser')
+
+
+    implementation libs.bundles.slf4j
+    implementation libs.notnull
+    implementation libs.guava
+
+    implementation dependencies.create(libs.guice.get()) {
+        exclude group: 'com.google.guava'
+    }
+    implementation libs.gson
+    implementation libs.zstd
+    implementation libs.bucket4j
+    implementation libs.crawlercommons
+    implementation libs.jsoup
+    implementation libs.fastutil
+    implementation libs.bundles.curator
+    implementation libs.bundles.mariadb
+    implementation libs.bundles.httpcomponents
+    implementation libs.commons.lang3
+
+    testImplementation libs.bundles.slf4j.test
+    testImplementation libs.bundles.junit
+    testImplementation libs.mockito
+
+    testImplementation libs.wiremock
+
+
+    testImplementation platform('org.testcontainers:testcontainers-bom:1.17.4')
+    testImplementation libs.commons.codec
+    testImplementation 'org.testcontainers:mariadb:1.17.4'
+    testImplementation 'org.testcontainers:junit-jupiter:1.17.4'
+    testImplementation project(':code:libraries:test-helpers')
+
+    testImplementation project(':code:processes:test-data')
+}
+

code/processes/new-domain-process/java/nu/marginalia/ndp/DomainEvaluator.java

@@ -0,0 +1,142 @@
+package nu.marginalia.ndp;
+
+
+import com.google.inject.Inject;
+import nu.marginalia.WmsaHome;
+import nu.marginalia.contenttype.ContentType;
+import nu.marginalia.contenttype.DocumentBodyToString;
+import nu.marginalia.coordination.DomainCoordinator;
+import nu.marginalia.link_parser.LinkParser;
+import nu.marginalia.model.EdgeDomain;
+import nu.marginalia.ndp.io.HttpClientProvider;
+import nu.marginalia.ndp.model.DomainToTest;
+import org.apache.hc.client5.http.classic.HttpClient;
+import org.apache.hc.core5.http.ClassicHttpResponse;
+import org.apache.hc.core5.http.io.entity.EntityUtils;
+import org.apache.hc.core5.http.io.support.ClassicRequestBuilder;
+import org.jsoup.Jsoup;
+import org.jsoup.nodes.Document;
+
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Objects;
+import java.util.concurrent.TimeUnit;
+
+
+public class DomainEvaluator {
+    private final HttpClient client;
+    private final String userAgentString = WmsaHome.getUserAgent().uaString();
+
+    private final LinkParser linkParser = new LinkParser();
+    private final DomainCoordinator domainCoordinator;
+    sealed interface FetchResult permits FetchSuccess, FetchFailure {}
+    record FetchSuccess(Document content) implements FetchResult {}
+    record FetchFailure(String reason) implements FetchResult {}
+
+    @Inject
+    public DomainEvaluator(DomainCoordinator domainCoordinator) throws NoSuchAlgorithmException, KeyManagementException {
+        this.domainCoordinator = domainCoordinator;
+        client = HttpClientProvider.createClient();
+    }
+
+    public boolean evaluateDomain(DomainToTest domain) throws Exception {
+        var edgeDomain = new EdgeDomain(domain.domainName());
+        try (var lock = domainCoordinator.lockDomain(edgeDomain)) {
+            var result = fetch(domain.domainName());
+
+            Instant start = Instant.now();
+
+            var ret = switch(result) {
+                case FetchSuccess(Document content) -> validateHtml(content, edgeDomain);
+                case FetchFailure failure -> false;
+            };
+
+            // Sleep for up to 1 second before we yield the lock to respect rate limits reasonably well
+            Instant end = Instant.now();
+            Duration sleepDuration = Duration.ofSeconds(1).minus(Duration.between(start, end));
+
+            if (sleepDuration.isPositive()) {
+                TimeUnit.MILLISECONDS.sleep(sleepDuration.toMillis());
+            }
+
+            return ret;
+        }
+    }
+
+    private boolean validateHtml(Document content, EdgeDomain domain) {
+        var rootUrl = domain.toRootUrlHttps();
+        var text = content.body().text();
+
+        if (text.length() < 100) {
+            return false; // Too short to be a valid page
+        }
+
+        if (text.contains("404 Not Found") || text.contains("Page not found")) {
+            return false; // Common indicators of a 404 page
+        }
+
+        for (var metaTag : content.select("meta")) {
+            if ("refresh".equalsIgnoreCase(metaTag.attr("http-equiv"))) {
+                return false; // Page has a refresh tag, very likely a parked domain
+            }
+        }
+
+        boolean hasInternalLink = false;
+
+        for (var atag : content.select("a")) {
+            var link = linkParser.parseLink(rootUrl, atag);
+            if (link.isEmpty()) {
+                continue; // Skip invalid links
+            }
+            var edgeUrl = link.get();
+            if (Objects.equals(domain, edgeUrl.getDomain())) {
+                hasInternalLink = true;
+            }
+        }
+
+        return hasInternalLink;
+    }
+
+    private FetchResult fetch(String domain) throws URISyntaxException {
+        var uri = new URI("https://" + domain + "/");
+
+        var request = ClassicRequestBuilder.get(uri)
+                .addHeader("User-Agent", userAgentString)
+                .addHeader("Accept-Encoding", "gzip")
+                .addHeader("Accept", "text/html,application/xhtml+xml;q=0.9")
+                .build();
+
+        try {
+            return client.execute(request, (rsp) -> responseHandler(rsp, domain));
+        } catch (Exception e) {
+            return new FetchFailure("Failed to fetch domain: " + e.getMessage());
+        }
+    }
+
+    private FetchResult responseHandler(ClassicHttpResponse rsp, String domain) {
+        if (rsp.getEntity() == null)
+            return new FetchFailure("No content returned from " + domain);
+
+        try {
+            int code = rsp.getCode();
+            byte[] content = rsp.getEntity().getContent().readAllBytes();
+
+            if (code >= 300) {
+                return new FetchFailure("Received HTTP " + code + " from " + domain);
+            }
+
+            ContentType contentType = ContentType.parse(rsp.getEntity().getContentType());
+            var html = DocumentBodyToString.getStringData(contentType, content);
+            return new FetchSuccess(Jsoup.parse(html));
+        }
+        catch (Exception e) {
+            EntityUtils.consumeQuietly(rsp.getEntity());
+            return new FetchFailure("Failed to read content from " + domain + ": " + e.getMessage());
+        }
+    }
+
+}

code/processes/new-domain-process/java/nu/marginalia/ndp/DomainNodeAllocator.java

@@ -0,0 +1,127 @@
+package nu.marginalia.ndp;
+
+import com.google.inject.Inject;
+import com.zaxxer.hikari.HikariDataSource;
+import nu.marginalia.nodecfg.NodeConfigurationService;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.PriorityQueue;
+import java.util.Set;
+
+/** DomainAllocator is responsible for assigning domains to partitions/nodes.
+ * This is ensured to make sure that domains are evenly distributed across the nodes.
+ */
+public class DomainNodeAllocator {
+
+    private final NodeConfigurationService nodeConfigurationService;
+    private final HikariDataSource dataSource;
+
+    private record NodeCount(int nodeId, int count)
+        implements Comparable<NodeCount>
+    {
+        public NodeCount incrementCount() {
+            return new NodeCount(nodeId, count + 1);
+        }
+
+        @Override
+        public int compareTo(@NotNull DomainNodeAllocator.NodeCount o) {
+            return Integer.compare(this.count, o.count);
+        }
+    }
+
+    private final PriorityQueue<NodeCount> countPerNode = new PriorityQueue<>();
+    volatile boolean initialized = false;
+
+    @Inject
+    public DomainNodeAllocator(NodeConfigurationService nodeConfigurationService, HikariDataSource dataSource) {
+        this.nodeConfigurationService = nodeConfigurationService;
+        this.dataSource = dataSource;
+
+        Thread.ofPlatform()
+                .name("DomainNodeAllocator::initialize()")
+                .start(this::initialize);
+    }
+
+
+    public void initialize() {
+        if (initialized) return;
+
+        Set<Integer> viableNodes = new HashSet<>();
+
+        // Find all viable nodes that can handle batch crawls
+        for (var node : nodeConfigurationService.getAll()) {
+            if (node.disabled())
+                continue;
+            if (node.profile().permitBatchCrawl())
+                viableNodes.add(node.node());
+        }
+
+        // Fetch the current counts of domains per node from the database
+        try (var conn = dataSource.getConnection();
+             var stmt = conn.prepareStatement("""
+                SELECT COUNT(*) AS CNT, NODE_AFFINITY
+                FROM EC_DOMAIN
+                WHERE NODE_AFFINITY>0
+                GROUP BY NODE_AFFINITY
+                """))
+        {
+
+            var rs = stmt.executeQuery();
+            while (rs.next()) {
+
+                int nodeId = rs.getInt("NODE_AFFINITY");
+                int count = rs.getInt("CNT");
+
+                if (viableNodes.remove(nodeId)) {
+                    countPerNode.add(new NodeCount(nodeId, count));
+                }
+            }
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to load domain counts from database", e);
+        }
+
+        // Add any remaining viable nodes that were not found in the database
+        for (int nodeId : viableNodes) {
+            countPerNode.add(new NodeCount(nodeId, 0));
+        }
+
+        initialized = true;
+    }
+
+    private void ensureInitialized() {
+        if (initialized) return;
+
+        synchronized (this) {
+            while (!initialized) {
+                try {
+                    // Wait until the initialization is complete
+                    this.wait(1000);
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                    throw new RuntimeException("DomainAllocator initialization interrupted", e);
+                }
+            }
+        }
+    }
+
+    public synchronized int totalCount() {
+        ensureInitialized();
+        return countPerNode.stream().mapToInt(NodeCount::count).sum();
+    }
+
+    /** Returns the next node ID to assign a domain to.
+     * This method is synchronized to ensure thread safety when multiple threads are allocating domains.
+     * The node ID returned is guaranteed to be one of the viable nodes configured in the system.
+     */
+    public synchronized int nextNodeId() {
+        ensureInitialized();
+
+        // Synchronized is fine here as this is not a hot path
+        // (and PriorityBlockingQueue won't help since we're re-adding the same element with a new count all the time)
+
+        NodeCount allocation = countPerNode.remove();
+        countPerNode.add(allocation.incrementCount());
+        return allocation.nodeId();
+    }
+}

code/processes/new-domain-process/java/nu/marginalia/ndp/DomainTestingQueue.java

@@ -0,0 +1,148 @@
+package nu.marginalia.ndp;
+
+import com.google.inject.Inject;
+import com.zaxxer.hikari.HikariDataSource;
+import nu.marginalia.ndp.model.DomainToTest;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.sql.Connection;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class DomainTestingQueue {
+    private final ArrayBlockingQueue<DomainToTest> queue = new ArrayBlockingQueue<>(1000);
+
+    // This will grow quite large, but should be manageable in memory, as theoretical maximum is around 100M domains,
+    // order of 2 GB in memory.
+    private final ConcurrentHashMap<String, Boolean> takenDomains = new ConcurrentHashMap<>();
+
+    private final HikariDataSource dataSource;
+
+    private static Logger logger = LoggerFactory.getLogger(DomainTestingQueue.class);
+
+    @Inject
+    public DomainTestingQueue(HikariDataSource dataSource) {
+        this.dataSource = dataSource;
+
+        Thread.ofPlatform()
+                .name("DomainTestingQueue::fetch()")
+                .start(this::fetch);
+    }
+
+    public DomainToTest next() throws InterruptedException {
+        return queue.take();
+    }
+
+    public void accept(DomainToTest domain, int nodeId) {
+        try (var conn = dataSource.getConnection();
+             var flagOkStmt = conn.prepareStatement("""
+                UPDATE NDP_NEW_DOMAINS
+                SET STATE='ACCEPTED'
+                WHERE DOMAIN_ID=?
+                """);
+             var assigNodeStmt = conn.prepareStatement("""
+                UPDATE EC_DOMAIN SET NODE_AFFINITY=?
+                WHERE ID=?
+                """)
+             )
+        {
+            conn.setAutoCommit(false);
+            flagOkStmt.setInt(1, domain.domainId());
+            flagOkStmt.executeUpdate();
+
+            assigNodeStmt.setInt(1, nodeId);
+            assigNodeStmt.setInt(2, domain.domainId());
+            assigNodeStmt.executeUpdate();
+            conn.commit();
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to accept domain in database", e);
+        }
+    }
+
+    public void reject(DomainToTest domain) {
+        try (var conn = dataSource.getConnection();
+             var stmt = conn.prepareStatement("""
+                UPDATE NDP_NEW_DOMAINS
+                SET STATE='REJECTED', CHECK_COUNT=CHECK_COUNT + 1
+                WHERE DOMAIN_ID=?
+                """))
+        {
+            conn.setAutoCommit(false);
+            stmt.setInt(1, domain.domainId());
+            stmt.executeUpdate();
+            conn.commit();
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to reject domain in database", e);
+        }
+    }
+
+    public void fetch() {
+        while (true) {
+            List<DomainToTest> domains = new ArrayList<>(2000);
+            try (var conn = dataSource.getConnection();
+                 var stmt = conn.prepareStatement("""
+                    SELECT DOMAIN_ID, DOMAIN_NAME
+                    FROM NDP_NEW_DOMAINS
+                    INNER JOIN EC_DOMAIN ON ID=DOMAIN_ID
+                    WHERE NDP_NEW_DOMAINS.STATE = 'NEW'
+                    ORDER BY PRIORITY DESC
+                    LIMIT 2000
+                    """))
+            {
+                var rs = stmt.executeQuery();
+
+                while (rs.next()) {
+                    int domainId = rs.getInt("DOMAIN_ID");
+                    String domainName = rs.getString("DOMAIN_NAME");
+                    if (takenDomains.put(domainName, true) != null) {
+                        logger.warn("Domain {} is already processed, skipping", domainName);
+                        continue; // Skip if already taken
+                    }
+                    domains.add(new DomainToTest(domainName, domainId));
+                }
+
+                if (domains.isEmpty()) {
+                    refreshQueue(conn);
+                }
+            }
+            catch (Exception e) {
+                throw new RuntimeException("Failed to fetch domains from database", e);
+            }
+
+            try {
+                for (var domain : domains) {
+                    queue.put(domain);
+                }
+            }
+            catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+                throw new RuntimeException("Domain fetching interrupted", e);
+            }
+        }
+    }
+
+    private void refreshQueue(Connection conn) {
+        logger.info("Refreshing domain queue in database");
+        try (var stmt = conn.createStatement()) {
+            conn.setAutoCommit(false);
+            logger.info("Revitalizing rejected domains");
+
+            // Revitalize rejected domains
+            stmt.executeUpdate("""
+                UPDATE NDP_NEW_DOMAINS
+                SET STATE='NEW'
+                WHERE NDP_NEW_DOMAINS.STATE = 'REJECTED'
+                AND DATE_ADD(TS_CHANGE, INTERVAL CHECK_COUNT DAY) > NOW()
+                """);
+            conn.commit();
+
+            logger.info("Queue refreshed successfully");
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to refresh queue in database", e);
+        }
+    }
+
+}

code/processes/new-domain-process/java/nu/marginalia/ndp/NdpMain.java

@@ -0,0 +1,162 @@
+package nu.marginalia.ndp;
+
+import com.google.gson.Gson;
+import com.google.inject.Guice;
+import com.google.inject.Inject;
+import com.google.inject.Injector;
+import nu.marginalia.WmsaHome;
+import nu.marginalia.coordination.DomainCoordinationModule;
+import nu.marginalia.db.DomainBlacklist;
+import nu.marginalia.geoip.GeoIpDictionary;
+import nu.marginalia.mq.MessageQueueFactory;
+import nu.marginalia.mqapi.ProcessInboxNames;
+import nu.marginalia.mqapi.ndp.NdpRequest;
+import nu.marginalia.ndp.model.DomainToTest;
+import nu.marginalia.process.ProcessConfiguration;
+import nu.marginalia.process.ProcessConfigurationModule;
+import nu.marginalia.process.ProcessMainClass;
+import nu.marginalia.process.control.ProcessHeartbeat;
+import nu.marginalia.service.module.DatabaseModule;
+import nu.marginalia.service.module.ServiceDiscoveryModule;
+import nu.marginalia.util.SimpleBlockingThreadPool;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.security.Security;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class NdpMain extends ProcessMainClass {
+
+    private static final Logger logger = LoggerFactory.getLogger(NdpMain.class);
+    private final DomainNodeAllocator domainNodeAllocator;
+    private final DomainTestingQueue domainTestingQueue;
+    private final ProcessHeartbeat processHeartbeat;
+    private final DomainEvaluator domainEvaluator;
+    private final DomainBlacklist domainBlacklist;
+
+    private final AtomicInteger domainCount = new AtomicInteger(0);
+
+    @Inject
+    public NdpMain(MessageQueueFactory messageQueueFactory,
+                   ProcessConfiguration config,
+                   DomainNodeAllocator domainNodeAllocator,
+                   DomainTestingQueue domainTestingQueue,
+                   DomainEvaluator domainEvaluator,
+                   DomainBlacklist domainBlacklist,
+                   ProcessHeartbeat processHeartbeat,
+                   Gson gson)
+    {
+        super(messageQueueFactory, config, gson, ProcessInboxNames.NDP_INBOX);
+
+        this.domainNodeAllocator = domainNodeAllocator;
+        this.domainEvaluator = domainEvaluator;
+        this.domainBlacklist = domainBlacklist;
+        this.domainTestingQueue = domainTestingQueue;
+        this.processHeartbeat = processHeartbeat;
+    }
+
+
+    public void run(int goalCount) throws InterruptedException {
+        logger.info("Wait for blacklist to load...");
+        domainBlacklist.waitUntilLoaded();
+
+        SimpleBlockingThreadPool threadPool = new SimpleBlockingThreadPool(
+                "NDP-Worker",
+                8,
+                10,
+                SimpleBlockingThreadPool.ThreadType.PLATFORM
+        );
+
+        logger.info("Starting NDP process");
+
+        int toInsertCount = goalCount - domainNodeAllocator.totalCount();
+
+        if (toInsertCount <= 0) {
+            logger.info("No new domains to process. Current count: " + domainNodeAllocator.totalCount());
+            return;
+        }
+
+        try (var hb = processHeartbeat.createAdHocTaskHeartbeat("Growing Index")) {
+            int cnt;
+            while ((cnt = domainCount.get()) < toInsertCount) {
+                if (cnt % 100 == 0) {
+                    hb.progress("Discovery Process", cnt, toInsertCount);
+                }
+
+                var nextDomain = domainTestingQueue.next();
+                threadPool.submit(() -> evaluateDomain(nextDomain));
+            }
+        }
+
+        threadPool.shutDown();
+        // Wait for all tasks to complete or give up after 1 hour
+        threadPool.awaitTermination(1, TimeUnit.HOURS);
+
+        logger.info("NDP process completed. Total domains processed: " + domainCount.get());
+
+    }
+
+
+    private void evaluateDomain(DomainToTest nextDomain) {
+        try {
+            if (domainEvaluator.evaluateDomain(nextDomain)) {
+                logger.info("Accepting: {}", nextDomain.domainName());
+                domainCount.incrementAndGet();
+                domainTestingQueue.accept(nextDomain, domainNodeAllocator.nextNodeId());
+            } else {
+                logger.info("Rejecting: {}", nextDomain.domainName());
+                domainTestingQueue.reject(nextDomain);
+            }
+        }
+        catch (Exception e) {
+            domainTestingQueue.reject(nextDomain);
+            logger.error("Error evaluating domain: " + nextDomain.domainId(), e);
+        }
+    }
+
+    public static void main(String[] args) throws Exception {
+        // Prevent Java from caching DNS lookups forever (filling up the system RAM as a result)
+        Security.setProperty("networkaddress.cache.ttl" , "3600");
+
+        // This must run *early*
+        System.setProperty("http.agent", WmsaHome.getUserAgent().uaString());
+
+        // If these aren't set properly, the JVM will hang forever on some requests
+        System.setProperty("sun.net.client.defaultConnectTimeout", "30000");
+        System.setProperty("sun.net.client.defaultReadTimeout", "30000");
+
+        // Set the maximum number of connections to keep alive in the connection pool
+        System.setProperty("jdk.httpclient.idleTimeout", "15"); // 15 seconds
+        System.setProperty("jdk.httpclient.connectionPoolSize", "256");
+
+        // We don't want to use too much memory caching sessions for https
+        System.setProperty("javax.net.ssl.sessionCacheSize", "2048");
+
+
+        Injector injector = Guice.createInjector(
+                new NdpModule(),
+                new ServiceDiscoveryModule(),
+                new DomainCoordinationModule(),
+                new ProcessConfigurationModule("ndp"),
+                new DatabaseModule(false)
+        );
+
+        GeoIpDictionary geoIpDictionary = injector.getInstance(GeoIpDictionary.class);
+
+        geoIpDictionary.waitReady(); // Ensure the GeoIpDictionary is ready before proceeding
+
+        NdpMain main = injector.getInstance(NdpMain.class);
+
+        var instructions = main.fetchInstructions(NdpRequest.class);
+
+        try {
+            main.run(instructions.value().goal());
+            instructions.ok();
+        }
+        catch (Throwable ex) {
+            logger.error("Error running ping process", ex);
+            instructions.err();
+        }
+    }
+}

code/processes/new-domain-process/java/nu/marginalia/ndp/NdpModule.java

@@ -0,0 +1,8 @@
+package nu.marginalia.ndp;
+
+import com.google.inject.AbstractModule;
+
+public class NdpModule extends AbstractModule {
+    public void configure() {
+    }
+}

code/processes/new-domain-process/java/nu/marginalia/ndp/io/HttpClientProvider.java

@@ -0,0 +1,126 @@
+package nu.marginalia.ndp.io;
+
+import com.google.inject.Provider;
+import org.apache.hc.client5.http.ConnectionKeepAliveStrategy;
+import org.apache.hc.client5.http.classic.HttpClient;
+import org.apache.hc.client5.http.config.ConnectionConfig;
+import org.apache.hc.client5.http.config.RequestConfig;
+import org.apache.hc.client5.http.cookie.StandardCookieSpec;
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.client5.http.impl.classic.HttpClients;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManager;
+import org.apache.hc.client5.http.impl.io.PoolingHttpClientConnectionManagerBuilder;
+import org.apache.hc.core5.http.HeaderElement;
+import org.apache.hc.core5.http.HeaderElements;
+import org.apache.hc.core5.http.HttpResponse;
+import org.apache.hc.core5.http.io.SocketConfig;
+import org.apache.hc.core5.http.message.MessageSupport;
+import org.apache.hc.core5.http.protocol.HttpContext;
+import org.apache.hc.core5.util.TimeValue;
+import org.apache.hc.core5.util.Timeout;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.security.KeyManagementException;
+import java.security.NoSuchAlgorithmException;
+import java.util.Iterator;
+import java.util.concurrent.TimeUnit;
+
+public class HttpClientProvider implements Provider<HttpClient> {
+    private static final HttpClient client;
+    private static PoolingHttpClientConnectionManager connectionManager;
+
+    private static final Logger logger = LoggerFactory.getLogger(HttpClientProvider.class);
+
+    static {
+        try {
+            client = createClient();
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    public static CloseableHttpClient createClient() throws NoSuchAlgorithmException, KeyManagementException {
+        final ConnectionConfig connectionConfig = ConnectionConfig.custom()
+                .setSocketTimeout(15, TimeUnit.SECONDS)
+                .setConnectTimeout(15, TimeUnit.SECONDS)
+                .setValidateAfterInactivity(TimeValue.ofSeconds(5))
+                .build();
+
+
+        connectionManager = PoolingHttpClientConnectionManagerBuilder.create()
+                .setMaxConnPerRoute(2)
+                .setMaxConnTotal(50)
+                .setDefaultConnectionConfig(connectionConfig)
+                .build();
+
+        connectionManager.setDefaultSocketConfig(SocketConfig.custom()
+                .setSoLinger(TimeValue.ofSeconds(-1))
+                .setSoTimeout(Timeout.ofSeconds(10))
+                .build()
+        );
+
+        Thread.ofPlatform().daemon(true).start(() -> {
+            try {
+                for (;;) {
+                    TimeUnit.SECONDS.sleep(15);
+                    logger.info("Connection pool stats: {}", connectionManager.getTotalStats());
+                }
+            }
+            catch (InterruptedException e) {
+                Thread.currentThread().interrupt();
+            }
+        });
+
+        final RequestConfig defaultRequestConfig = RequestConfig.custom()
+                .setCookieSpec(StandardCookieSpec.IGNORE)
+                .setResponseTimeout(10, TimeUnit.SECONDS)
+                .setConnectionRequestTimeout(5, TimeUnit.MINUTES)
+                .build();
+
+        return HttpClients.custom()
+                .setConnectionManager(connectionManager)
+                .setRetryStrategy(new RetryStrategy())
+                .setKeepAliveStrategy(new ConnectionKeepAliveStrategy() {
+                    // Default keep-alive duration is 3 minutes, but this is too long for us,
+                    // as we are either going to re-use it fairly quickly or close it for a long time.
+                    //
+                    // So we set it to 30 seconds or clamp the server-provided value to a minimum of 10 seconds.
+                    private static final TimeValue defaultValue = TimeValue.ofSeconds(30);
+
+                    @Override
+                    public TimeValue getKeepAliveDuration(HttpResponse response, HttpContext context) {
+                        final Iterator<HeaderElement> it = MessageSupport.iterate(response, HeaderElements.KEEP_ALIVE);
+
+                        while (it.hasNext()) {
+                            final HeaderElement he = it.next();
+                            final String param = he.getName();
+                            final String value = he.getValue();
+
+                            if (value == null)
+                                continue;
+                            if (!"timeout".equalsIgnoreCase(param))
+                                continue;
+
+                            try {
+                                long timeout = Long.parseLong(value);
+                                timeout = Math.clamp(timeout, 30, defaultValue.toSeconds());
+                                return TimeValue.ofSeconds(timeout);
+                            } catch (final NumberFormatException ignore) {
+                                break;
+                            }
+                        }
+                        return defaultValue;
+                    }
+                })
+                .disableRedirectHandling()
+                .setDefaultRequestConfig(defaultRequestConfig)
+                .build();
+    }
+
+    @Override
+    public HttpClient get() {
+        return client;
+    }
+}
+

code/processes/new-domain-process/java/nu/marginalia/ndp/io/RetryStrategy.java

@@ -0,0 +1,79 @@
+package nu.marginalia.ndp.io;
+
+import org.apache.hc.client5.http.HttpHostConnectException;
+import org.apache.hc.client5.http.HttpRequestRetryStrategy;
+import org.apache.hc.core5.http.HttpRequest;
+import org.apache.hc.core5.http.HttpResponse;
+import org.apache.hc.core5.http.protocol.HttpContext;
+import org.apache.hc.core5.util.TimeValue;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.net.ssl.SSLException;
+import java.io.IOException;
+import java.net.SocketException;
+import java.net.SocketTimeoutException;
+import java.net.UnknownHostException;
+
+public class RetryStrategy implements HttpRequestRetryStrategy {
+    private static final Logger logger = LoggerFactory.getLogger(RetryStrategy.class);
+
+    @Override
+    public boolean retryRequest(HttpRequest request, IOException exception, int executionCount, HttpContext context) {
+        return switch (exception) {
+            case SocketTimeoutException ste -> false;
+            case SSLException ssle -> false;
+            case UnknownHostException uhe -> false;
+            case HttpHostConnectException ex -> executionCount < 2;
+            case SocketException ex -> executionCount < 2;
+            default -> executionCount <= 3;
+        };
+    }
+
+    @Override
+    public boolean retryRequest(HttpResponse response, int executionCount, HttpContext context) {
+        return switch (response.getCode()) {
+            case 500, 503 -> executionCount <= 2;
+            case 429 -> executionCount <= 3;
+            default -> false;
+        };
+    }
+
+    @Override
+    public TimeValue getRetryInterval(HttpRequest request, IOException exception, int executionCount, HttpContext context) {
+        return TimeValue.ofSeconds(1);
+    }
+
+    @Override
+    public TimeValue getRetryInterval(HttpResponse response, int executionCount, HttpContext context) {
+
+        int statusCode = response.getCode();
+
+        // Give 503 a bit more time
+        if (statusCode == 503) return TimeValue.ofSeconds(5);
+
+        if (statusCode == 429) {
+            // get the Retry-After header
+            var retryAfterHeader = response.getFirstHeader("Retry-After");
+            if (retryAfterHeader == null) {
+                return TimeValue.ofSeconds(3);
+            }
+
+            String retryAfter = retryAfterHeader.getValue();
+            if (retryAfter == null) {
+                return TimeValue.ofSeconds(2);
+            }
+
+            try {
+                int retryAfterTime = Integer.parseInt(retryAfter);
+                retryAfterTime = Math.clamp(retryAfterTime, 1, 5);
+
+                return TimeValue.ofSeconds(retryAfterTime);
+            } catch (NumberFormatException e) {
+                logger.warn("Invalid Retry-After header: {}", retryAfter);
+            }
+        }
+
+        return TimeValue.ofSeconds(2);
+    }
+}

code/processes/new-domain-process/java/nu/marginalia/ndp/model/DomainToTest.java

@@ -0,0 +1,4 @@
+package nu.marginalia.ndp.model;
+
+public record DomainToTest(String domainName, int domainId) {
+}

code/processes/ping-process/README.md

@@ -0,0 +1,12 @@
+The ping process (which has nothing to do with ICMP ping) keeps track of 
+the aliveness of websites.  It also gathers fingerprint information about
+the security posture of the website, as well as DNS information.
+
+This is kept to build an idea of when a website is down, and to identify
+ownership changes, as well as other significant events in the lifecycle
+of a website.
+
+# Central Classes
+
+* [PingMain](java/nu/marginalia/ping/PingMain.java) main class.
+* [PingJobScheduler](java/nu/marginalia/ping/PingJobScheduler.java) service that dispatches pings.

code/processes/process-mq-api/java/nu/marginalia/mqapi/ProcessInboxNames.java

@@ -4,6 +4,7 @@ public class ProcessInboxNames {
     public static final String CONVERTER_INBOX = "converter";
     public static final String LOADER_INBOX = "loader";
     public static final String PING_INBOX = "ping";
+    public static final String NDP_INBOX = "ndp";
     public static final String CRAWLER_INBOX = "crawler";
     public static final String LIVE_CRAWLER_INBOX = "live-crawler";
 

code/processes/process-mq-api/java/nu/marginalia/mqapi/ndp/NdpRequest.java

@@ -0,0 +1,4 @@
+package nu.marginalia.mqapi.ndp;
+
+public record NdpRequest(int goal) {
+}

code/processes/readme.md

@@ -25,6 +25,11 @@ into the [MariaDB database](../common/db).
 The [index-construction-process](index-constructor-process/) constructs indices from
 the data generated by the loader.
 
+## 5. Other Processes
+
+* Ping Process: The [ping-process](ping-process/) keeps track of the aliveness of websites, gathering fingerprint information about the security posture of the website, as well as DNS information.
+* Live-Crawling Process: The [live-crawling-process](live-crawling-process/) is a process that crawls websites in real-time based on RSS feeds, updating a smaller index with the latest content.
+
 ## Overview 
 
 Schematically the crawling and loading process looks like this:

settings.gradle

@@ -69,6 +69,7 @@ include 'code:processes:crawling-process:ft-link-parser'
 include 'code:processes:crawling-process:ft-content-type'
 include 'code:processes:live-crawling-process'
 include 'code:processes:ping-process'
+include 'code:processes:new-domain-process'
 
 include 'code:processes:process-mq-api'