netty: Allow disabling server keep-alive enforcement via permitKeepAliveTime

This change effectively makes the permitKeepAliveTime change consistent, similar to keepAliveTime. We can now disable this mechanism.

Currently, we can't do this, because even if we pass Long.MAX_VALUE, KeepAliveEnforcer will substitute its own value.

Author: therepanic

core/src/main/java/io/grpc/internal/GrpcUtil.java

@@ -241,6 +241,17 @@ public byte[] parseAsciiString(byte[] serialized) {
    */
   public static final long DEFAULT_SERVER_KEEPALIVE_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(20L);
 
+  /**
+   * The default minimum time between client keepalive pings permitted by server.
+   */
+  public static final long DEFAULT_SERVER_PERMIT_KEEPALIVE_TIME_NANOS  =
+          TimeUnit.MINUTES.toNanos(5);
+
+  /**
+   * The magic permit keepalive time value that disables server keepalive enforcement.
+   */
+  public static final long SERVER_PERMIT_KEEPALIVE_TIME_NANOS_DISABLED = Long.MAX_VALUE;
+
   /**
    * The magic keepalive time value that disables keepalive.
    */

core/src/main/java/io/grpc/internal/KeepAliveEnforcer.java

@@ -46,7 +46,8 @@ public KeepAliveEnforcer(boolean permitWithoutCalls, long minTime, TimeUnit unit
     Preconditions.checkArgument(minTime >= 0, "minTime must be non-negative: %s", minTime);
 
     this.permitWithoutCalls = permitWithoutCalls;
-    this.minTimeNanos = Math.min(unit.toNanos(minTime), IMPLICIT_PERMIT_TIME_NANOS);
+    this.minTimeNanos = minTime == Long.MAX_VALUE ? Long.MAX_VALUE
+            : Math.min(unit.toNanos(minTime),IMPLICIT_PERMIT_TIME_NANOS);
     this.ticker = ticker;
     this.epoch = ticker.nanoTime();
     lastValidPingTime = epoch;
@@ -55,6 +56,9 @@ public KeepAliveEnforcer(boolean permitWithoutCalls, long minTime, TimeUnit unit
   /** Returns {@code false} when client is misbehaving and should be disconnected. */
   @CheckReturnValue
   public boolean pingAcceptable() {
+    if (minTimeNanos == Long.MAX_VALUE) {
+      return true;
+    }
     long now = ticker.nanoTime();
     boolean valid;
     if (!hasOutstandingCalls && !permitWithoutCalls) {

core/src/test/java/io/grpc/internal/KeepAliveEnforcerTest.java

@@ -165,6 +165,20 @@ public void permitsWhenTimeOverflows() {
     assertThat(enforcer.pingAcceptable()).isTrue();
   }
 
+  @Test
+  public void permitAllWhenDisabled() {
+    KeepAliveEnforcer enforcer = new KeepAliveEnforcer(
+        false, Long.MAX_VALUE, TimeUnit.NANOSECONDS, ticker);
+    enforcer.onTransportIdle();
+    for (int i = 0; i < LARGE_NUMBER; i++) {
+      assertThat(enforcer.pingAcceptable()).isTrue();
+    }
+    enforcer.onTransportActive();
+    for (int i = 0; i < LARGE_NUMBER; i++) {
+      assertThat(enforcer.pingAcceptable()).isTrue();
+    }
+  }
+
   @Test
   public void resetCounters_resetsStrikes() {
     KeepAliveEnforcer enforcer = new KeepAliveEnforcer(false, 1, TimeUnit.NANOSECONDS, ticker);

netty/src/main/java/io/grpc/netty/NettyServerBuilder.java

@@ -22,7 +22,9 @@
 import static io.grpc.internal.GrpcUtil.DEFAULT_MAX_MESSAGE_SIZE;
 import static io.grpc.internal.GrpcUtil.DEFAULT_SERVER_KEEPALIVE_TIMEOUT_NANOS;
 import static io.grpc.internal.GrpcUtil.DEFAULT_SERVER_KEEPALIVE_TIME_NANOS;
+import static io.grpc.internal.GrpcUtil.DEFAULT_SERVER_PERMIT_KEEPALIVE_TIME_NANOS;
 import static io.grpc.internal.GrpcUtil.SERVER_KEEPALIVE_TIME_NANOS_DISABLED;
+import static io.grpc.internal.GrpcUtil.SERVER_PERMIT_KEEPALIVE_TIME_NANOS_DISABLED;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -113,7 +115,7 @@ public final class NettyServerBuilder extends ForwardingServerBuilder<NettyServe
   private long maxConnectionAgeInNanos = MAX_CONNECTION_AGE_NANOS_DISABLED;
   private long maxConnectionAgeGraceInNanos = MAX_CONNECTION_AGE_GRACE_NANOS_INFINITE;
   private boolean permitKeepAliveWithoutCalls;
-  private long permitKeepAliveTimeInNanos = TimeUnit.MINUTES.toNanos(5);
+  private long permitKeepAliveTimeInNanos = DEFAULT_SERVER_PERMIT_KEEPALIVE_TIME_NANOS;
   private int maxRstCount;
   private long maxRstPeriodNanos;
   private Attributes eagAttributes = Attributes.EMPTY;
@@ -656,6 +658,9 @@ public NettyServerBuilder permitKeepAliveTime(long keepAliveTime, TimeUnit timeU
     checkArgument(keepAliveTime >= 0, "permit keepalive time must be non-negative: %s",
         keepAliveTime);
     permitKeepAliveTimeInNanos = timeUnit.toNanos(keepAliveTime);
+    if (permitKeepAliveTimeInNanos >= AS_LARGE_AS_INFINITE) {
+      permitKeepAliveTimeInNanos = SERVER_PERMIT_KEEPALIVE_TIME_NANOS_DISABLED;
+    }
     return this;
   }