feat: add jitter to max lifetime in connection pool

vertx-pg-client/src/test/java/io/vertx/tests/pgclient/PgPoolTest.java

@@ -34,17 +34,21 @@
 import io.vertx.tests.sqlclient.ProxyServer;
 import org.junit.Rule;
 import org.junit.Test;
+import org.testcontainers.shaded.com.trilead.ssh2.ConnectionInfo;
 
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collector;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 import static java.util.stream.Collectors.mapping;
 import static java.util.stream.Collectors.toList;
@@ -619,4 +623,63 @@ public void testConnectionClosedInHook(TestContext ctx) {
       }));
     }));
   }
+
+  @Test
+  @Repeat(2)
+  public void testConnectionJitter(TestContext ctx) {
+    PoolOptions poolOptions = new PoolOptions()
+      .setMaxSize(1)
+      .setMaxLifetime(3000)
+      .setMaxLifetimeUnit(TimeUnit.MILLISECONDS)
+      .setJitter(1)
+      .setJitterUnit(TimeUnit.SECONDS)
+      .setPoolCleanerPeriod(50);
+
+    Pool pool = createPool(options, poolOptions);
+    Async latch = ctx.async();
+
+    List<Integer> pids = Collections.synchronizedList(new ArrayList<>());
+    List<Long> times = Collections.synchronizedList(new ArrayList<>());
+    AtomicInteger lastPid = new AtomicInteger(-1);
+    AtomicLong timerId = new AtomicLong();
+
+    Consumer<TestContext> checkPid = testCtx -> {
+      pool.query("SELECT pg_backend_pid() as pid")
+        .execute()
+        .onComplete(testCtx.asyncAssertSuccess(rs -> {
+          int currentPid = rs.iterator().next().getInteger("pid");
+          if (lastPid.get() != currentPid) {
+            pids.add(currentPid);
+            times.add(System.currentTimeMillis());
+            lastPid.set(currentPid);
+
+            if (pids.size() == 3) {
+              vertx.cancelTimer(timerId.get());
+              long diff1to2 = times.get(1) - times.get(0);
+              long diff2to3 = times.get(2) - times.get(1);
+
+              // Verify time ranges
+              int maxLifetime = 3000;
+              int jitter = 1000;
+              int buffer = 100;
+              int lowerBound = maxLifetime - jitter + buffer;
+              int upperBound = maxLifetime + jitter + buffer;
+
+              ctx.assertTrue(diff1to2 >= lowerBound && diff1to2 <= upperBound,
+                String.format("Time between PIDs %d->%d (%dms) should be between %dms and %dms",
+                  pids.get(0), pids.get(1), diff1to2, lowerBound, upperBound));
+
+              ctx.assertTrue(diff2to3 >= lowerBound && diff2to3 <= upperBound,
+                String.format("Time between PIDs %d->%d (%dms) should be between %dms and %dms",
+                  pids.get(1), pids.get(2), diff2to3, lowerBound, upperBound));
+
+              pool.close().onComplete(ctx.asyncAssertSuccess(v -> latch.complete()));
+            }
+          }
+        }));
+    };
+
+    timerId.set(vertx.setPeriodic(30, id -> checkPid.accept(ctx)));
+    latch.awaitSuccess(20000);
+  }
 }

vertx-sql-client/src/main/generated/io/vertx/sqlclient/PoolOptionsConverter.java

@@ -44,6 +44,16 @@ static void fromJson(Iterable<java.util.Map.Entry<String, Object>> json, PoolOpt
             obj.setMaxLifetime(((Number)member.getValue()).intValue());
           }
           break;
+        case "jitter":
+          if (member.getValue() instanceof Number) {
+            obj.setJitter(((Number)member.getValue()).intValue());
+          }
+          break;
+        case "jitterUnit":
+          if (member.getValue() instanceof String) {
+            obj.setJitterUnit(java.util.concurrent.TimeUnit.valueOf((String)member.getValue()));
+          }
+          break;
         case "poolCleanerPeriod":
           if (member.getValue() instanceof Number) {
             obj.setPoolCleanerPeriod(((Number)member.getValue()).intValue());
@@ -93,6 +103,10 @@ static void toJson(PoolOptions obj, java.util.Map<String, Object> json) {
       json.put("maxLifetimeUnit", obj.getMaxLifetimeUnit().name());
     }
     json.put("maxLifetime", obj.getMaxLifetime());
+    json.put("jitter", obj.getJitter());
+    if (obj.getJitterUnit() != null) {
+      json.put("jitterUnit", obj.getJitterUnit().name());
+    }
     json.put("poolCleanerPeriod", obj.getPoolCleanerPeriod());
     if (obj.getConnectionTimeoutUnit() != null) {
       json.put("connectionTimeoutUnit", obj.getConnectionTimeoutUnit().name());

vertx-sql-client/src/main/java/io/vertx/sqlclient/PoolOptions.java

@@ -93,6 +93,16 @@ public class PoolOptions {
    */
   public static final int DEFAULT_EVENT_LOOP_SIZE = 0;
 
+  /**
+   * Default jitter value = 0
+   */
+  public static final int DEFAULT_JITTER = 0;
+
+  /**
+   * Default jitter unit = milliseconds
+   */
+  public static final TimeUnit DEFAULT_JITTER_UNIT = TimeUnit.SECONDS;
+
   private int maxSize = DEFAULT_MAX_SIZE;
   private int maxWaitQueueSize = DEFAULT_MAX_WAIT_QUEUE_SIZE;
   private int idleTimeout = DEFAULT_IDLE_TIMEOUT;
@@ -105,7 +115,9 @@ public class PoolOptions {
   private boolean shared = DEFAULT_SHARED_POOL;
   private String name = DEFAULT_NAME;
   private int eventLoopSize = DEFAULT_EVENT_LOOP_SIZE;
-
+  private int jitter = DEFAULT_JITTER;
+  private TimeUnit jitterUnit = DEFAULT_JITTER_UNIT;
+
   public PoolOptions() {
   }
 
@@ -241,6 +253,49 @@ public PoolOptions setMaxLifetime(int maxLifetime) {
     return this;
   }
 
+  /**
+   * Get the jitter value that will be applied to maxLifetime.
+   *
+   * @return the jitter value in milliseconds
+   */
+  public int getJitter() {
+    return this.jitter;
+  }
+
+  /**
+   * Set the jitter value, to be applied to maxLifetime.
+   *
+   * @param jitter the jitter value
+   * @return a reference to this, so the API can be used fluently
+   */
+  public PoolOptions setJitter(int jitter) {
+    if (jitter < 0) {
+      throw new IllegalArgumentException("jitter must be >= 0");
+    }
+    this.jitter = jitter;
+    return this;
+  }
+
+  /**
+   * Get the time unit for the jitter value.
+   *
+   * @return the jitter time unit
+   */
+  public TimeUnit getJitterUnit() {
+    return this.jitterUnit;
+  }
+
+  /**
+   * Set the time unit for the jitter value.
+   *
+   * @param jitterUnit the jitter time unit
+   * @return a reference to this, so the API can be used fluently
+   */
+  public PoolOptions setJitterUnit(TimeUnit jitterUnit) {
+    this.jitterUnit = jitterUnit;
+    return this;
+  }
+
   /**
    * @return the connection pool cleaner period in ms.
    */

vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/pool/SqlConnectionPool.java

@@ -32,6 +32,7 @@
 import io.vertx.sqlclient.spi.DatabaseMetadata;
 
 import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
@@ -56,6 +57,7 @@ public class SqlConnectionPool {
   private final boolean pipelined;
   private final long idleTimeout;
   private final long maxLifetime;
+  private final long jitter;
   private final int maxSize;
 
   public SqlConnectionPool(Function<Context, Future<SqlConnection>> connectionProvider,
@@ -66,6 +68,7 @@ public SqlConnectionPool(Function<Context, Future<SqlConnection>> connectionProv
                            VertxInternal vertx,
                            long idleTimeout,
                            long maxLifetime,
+                           long jitter,
                            int maxSize,
                            boolean pipelined,
                            int maxWaitQueueSize,
@@ -82,6 +85,7 @@ public SqlConnectionPool(Function<Context, Future<SqlConnection>> connectionProv
     this.pipelined = pipelined;
     this.idleTimeout = idleTimeout;
     this.maxLifetime = maxLifetime;
+    this.jitter = jitter;
     this.maxSize = maxSize;
     this.hook = hook;
     this.connectionProvider = connectionProvider;
@@ -309,7 +313,8 @@ public class PooledConnection implements Connection, Connection.Holder {
       this.factory = factory;
       this.conn = conn;
       this.listener = listener;
-      this.lifetimeEvictionTimestamp = maxLifetime > 0 ? System.currentTimeMillis() + maxLifetime : Long.MAX_VALUE;
+      long randomizedJitter = (maxLifetime > 0 && jitter > 0 && maxLifetime > jitter) ? ThreadLocalRandom.current().nextLong(-jitter, jitter + 1) : 0;
+      this.lifetimeEvictionTimestamp = maxLifetime > 0 ? System.currentTimeMillis() + maxLifetime + randomizedJitter : Long.MAX_VALUE;
       refresh();
     }
 

vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/pool/PoolImpl.java

@@ -49,6 +49,7 @@ public class PoolImpl extends SqlClientBase implements Pool, Closeable {
   private final long idleTimeout;
   private final long connectionTimeout;
   private final long maxLifetime;
+  private final long jitter;
   private final long cleanerPeriod;
   private final boolean pipelined;
   private final Handler<SqlConnection> connectionInitializer;
@@ -80,11 +81,12 @@ public PoolImpl(VertxInternal vertx,
     this.idleTimeout = MILLISECONDS.convert(poolOptions.getIdleTimeout(), poolOptions.getIdleTimeoutUnit());
     this.connectionTimeout = MILLISECONDS.convert(poolOptions.getConnectionTimeout(), poolOptions.getConnectionTimeoutUnit());
     this.maxLifetime = MILLISECONDS.convert(poolOptions.getMaxLifetime(), poolOptions.getMaxLifetimeUnit());
+    this.jitter = MILLISECONDS.convert(poolOptions.getJitter(), poolOptions.getJitterUnit());
     this.cleanerPeriod = poolOptions.getPoolCleanerPeriod();
     this.timerID = -1L;
     this.pipelined = pipelined;
     this.vertx = vertx;
-    this.pool = new SqlConnectionPool(connectionProvider, poolMetrics, hook, afterAcquire, beforeRecycle, vertx, idleTimeout, maxLifetime, poolOptions.getMaxSize(), pipelined, poolOptions.getMaxWaitQueueSize(), poolOptions.getEventLoopSize());
+    this.pool = new SqlConnectionPool(connectionProvider, poolMetrics, hook, afterAcquire, beforeRecycle, vertx, idleTimeout, maxLifetime, jitter, poolOptions.getMaxSize(), pipelined, poolOptions.getMaxWaitQueueSize(), poolOptions.getEventLoopSize());
     this.closeFuture = closeFuture;
     this.connectionInitializer = connectionInitializer;
   }