(blacklist) Clean up blacklist impl

The domain blacklist blocked the start-up of each process that injected it, adding like 30 seconds to the start-up time in prod.

This change moves the loading to a separate thread entirely.  For threads or processes that require the blacklist to be definitely loaded, a helper method was added that blocks until that time.

code/common/db/src/main/java/nu/marginalia/db/DomainBlacklistImpl.java

@@ -4,11 +4,10 @@ import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import com.zaxxer.hikari.HikariDataSource;
 import gnu.trove.set.hash.TIntHashSet;
-import io.reactivex.rxjava3.schedulers.Schedulers;
-import lombok.SneakyThrows;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.sql.SQLException;
 import java.util.concurrent.TimeUnit;
 
 @Singleton
@@ -17,33 +16,67 @@ public class DomainBlacklistImpl implements DomainBlacklist {
     private final HikariDataSource dataSource;
     private final Logger logger = LoggerFactory.getLogger(getClass());
     private final boolean blacklistDisabled = Boolean.getBoolean("blacklist.disable");
+
+    private volatile boolean isLoaded = false;
+
     @Inject
     public DomainBlacklistImpl(HikariDataSource dataSource) {
         this.dataSource = dataSource;
 
-        Schedulers.io().schedulePeriodicallyDirect(this::updateSpamList, 5, 600, TimeUnit.SECONDS);
+        Thread.ofPlatform().daemon().name("BlacklistUpdater").start(this::updateSpamList);
-
-        updateSpamList();
     }
 
     private void updateSpamList() {
+        // If the blacklist is disabled, we don't need to do anything
+        if (blacklistDisabled) {
+            isLoaded = true;
 
-        try {
+            flagLoaded();
-            int oldSetSize = spamDomainSet.size();
 
+            return;
+        }
+
+        for (;;) {
             spamDomainSet = getSpamDomains();
 
-            if (oldSetSize == 0 && spamDomainSet.size() > 0) {
+            // Set the flag to true after the first loading attempt, regardless of success,
-                logger.info("Synchronized {} spam domains", spamDomainSet.size());
+            // to avoid deadlocking threads that are waiting for this condition
+            flagLoaded();
+
+            // Sleep for 10 minutes before trying again
+            try {
+                TimeUnit.MINUTES.sleep(10);
+            }
+            catch (InterruptedException ex) {
+                break;
             }
         }
-        catch (Exception ex) {
+
-            logger.error("Failed to synchronize spam domains", ex);
+    }
+
+    private void flagLoaded() {
+        if (!isLoaded) {
+            synchronized (this) {
+                isLoaded = true;
+                notifyAll();
+            }
         }
     }
 
+    /** Block until the blacklist has been loaded */
+    public boolean waitUntilLoaded() throws InterruptedException {
+        if (!isLoaded) {
+            synchronized (this) {
+                while (!isLoaded) {
+                    wait(5000);
+                }
+            }
+        }
+
+        return true;
+    }
+
 
-    @SneakyThrows
     public TIntHashSet getSpamDomains() {
         final TIntHashSet result = new TIntHashSet(1_000_000);
 
@@ -52,15 +85,25 @@ public class DomainBlacklistImpl implements DomainBlacklist {
         }
 
         try (var connection = dataSource.getConnection()) {
-            try (var stmt = connection.prepareStatement("SELECT EC_DOMAIN.ID FROM EC_DOMAIN INNER JOIN EC_DOMAIN_BLACKLIST ON (EC_DOMAIN_BLACKLIST.URL_DOMAIN = EC_DOMAIN.DOMAIN_TOP OR EC_DOMAIN_BLACKLIST.URL_DOMAIN = EC_DOMAIN.DOMAIN_NAME)")) {
+            try (var stmt = connection.prepareStatement("""
+                    SELECT EC_DOMAIN.ID 
+                    FROM EC_DOMAIN 
+                    INNER JOIN EC_DOMAIN_BLACKLIST 
+                    ON (EC_DOMAIN_BLACKLIST.URL_DOMAIN = EC_DOMAIN.DOMAIN_TOP 
+                     OR EC_DOMAIN_BLACKLIST.URL_DOMAIN = EC_DOMAIN.DOMAIN_NAME)
+                 """))
+            {
                 stmt.setFetchSize(1000);
                 var rsp = stmt.executeQuery();
                 while (rsp.next()) {
                     result.add(rsp.getInt(1));
                 }
             }
+        } catch (SQLException ex) {
+            logger.error("Failed to load spam domain list", ex);
         }
 
+
         return result;
     }