From fca258467781ac60913d253aa6c6355aabb46ca3 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 7 Oct 2024 11:45:24 +0000
Subject: [PATCH 01/27] grpc-core: combined epoch seconds and nanos changes in
 TimeProvider

---
 core/src/main/java/io/grpc/internal/TimeProvider.java | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index b0ea147ada1..41fdf87d185 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -16,6 +16,7 @@
 
 package io.grpc.internal;
 
+import java.time.Instant;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -29,7 +30,10 @@ public interface TimeProvider {
   TimeProvider SYSTEM_TIME_PROVIDER = new TimeProvider() {
     @Override
     public long currentTimeNanos() {
-      return TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis());
+      Instant instant = Instant.now();
+      int nanos = instant.getNano();
+      long epochSeconds = instant.getEpochSecond();
+      return nanos + epochSeconds;
     }
   };
 }

From 12b9b1ac32b8843c45cb0fc47c2797ea883e6afe Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Tue, 8 Oct 2024 08:25:08 +0000
Subject: [PATCH 02/27] grpc-core: combined epoch seconds and nanos changes in
 TimeProvider

---
 core/src/main/java/io/grpc/internal/TimeProvider.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index 41fdf87d185..d48d58cacba 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -33,7 +33,7 @@ public long currentTimeNanos() {
       Instant instant = Instant.now();
       int nanos = instant.getNano();
       long epochSeconds = instant.getEpochSecond();
-      return nanos + epochSeconds;
+      return Long.parseLong("" + epochSeconds + nanos);
     }
   };
 }

From 3d538d8c11c282af68617583be6fb358ca0ac954 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Tue, 8 Oct 2024 09:22:28 +0000
Subject: [PATCH 03/27] grpc-core: Fixed checkstyle issue

---
 core/src/main/java/io/grpc/internal/TimeProvider.java | 1 -
 1 file changed, 1 deletion(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index d48d58cacba..ad7de2401be 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -17,7 +17,6 @@
 package io.grpc.internal;
 
 import java.time.Instant;
-import java.util.concurrent.TimeUnit;
 
 /**
  * Time source representing the current system time in nanos. Used to inject a fake clock

From 9d04a747e72c0ddae4bf02ff47ffc82516026fd2 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Tue, 8 Oct 2024 09:58:32 +0000
Subject: [PATCH 04/27] grpc-core: added the comment

---
 core/src/main/java/io/grpc/internal/TimeProvider.java | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index ad7de2401be..a618f384841 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -32,6 +32,7 @@ public long currentTimeNanos() {
       Instant instant = Instant.now();
       int nanos = instant.getNano();
       long epochSeconds = instant.getEpochSecond();
+      // combining seconds and nanos part and returning the timestamp in nanoseconds
       return Long.parseLong("" + epochSeconds + nanos);
     }
   };

From 9c564dc382576e1dee18f476048fbb7965d54e3c Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Tue, 8 Oct 2024 11:24:37 +0000
Subject: [PATCH 05/27] grpc-core: removed the comment

---
 core/src/main/java/io/grpc/internal/TimeProvider.java | 1 -
 1 file changed, 1 deletion(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index a618f384841..ad7de2401be 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -32,7 +32,6 @@ public long currentTimeNanos() {
       Instant instant = Instant.now();
       int nanos = instant.getNano();
       long epochSeconds = instant.getEpochSecond();
-      // combining seconds and nanos part and returning the timestamp in nanoseconds
       return Long.parseLong("" + epochSeconds + nanos);
     }
   };

From a64afccf051b58830a98b4de5a177ec662517252 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Wed, 9 Oct 2024 10:47:20 +0000
Subject: [PATCH 06/27] grpc-core: Fixed Review points along with junits

---
 .../java/io/grpc/internal/TimeProvider.java   |  2 +-
 .../io/grpc/internal/TimeProviderTest.java    | 43 +++++++++++++++++++
 2 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 core/src/test/java/io/grpc/internal/TimeProviderTest.java

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index ad7de2401be..efc22a63777 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -32,7 +32,7 @@ public long currentTimeNanos() {
       Instant instant = Instant.now();
       int nanos = instant.getNano();
       long epochSeconds = instant.getEpochSecond();
-      return Long.parseLong("" + epochSeconds + nanos);
+      return epochSeconds * 1_000_000_000L + nanos;
     }
   };
 }
diff --git a/core/src/test/java/io/grpc/internal/TimeProviderTest.java b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
new file mode 100644
index 00000000000..239379f0dcb
--- /dev/null
+++ b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2017 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+import static org.junit.Assert.assertTrue;
+
+import java.time.Instant;
+import org.junit.Test;
+
+/**
+ *  Unit tests for {@link TimeProvider}.
+ */
+public class TimeProviderTest {
+  @Test
+  public void testCurrentTimeNanos() {
+
+    // Get the current time from the TimeProvider
+    long actualTimeNanos = TimeProvider.SYSTEM_TIME_PROVIDER.currentTimeNanos();
+
+    // Get the current time from Instant for comparison
+    Instant instantNow = Instant.now();
+    long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
+
+    // Validate the time returned is close to the expected value within a tolerance.
+    long toleranceOfTwoMilliSecond = 2_000_000L; // 2 millisecond tolerance in nanoseconds
+    assertTrue("The current time in nanoseconds should be close to the expected time.",
+        Math.abs(actualTimeNanos - expectedTimeNanos) < toleranceOfTwoMilliSecond);
+  }
+}

From 34d7c1dd39d6b795e9e89fbfefd764dce6425e7d Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Thu, 10 Oct 2024 08:07:00 +0000
Subject: [PATCH 07/27] grpc-core: Fixed Review points

---
 core/src/test/java/io/grpc/internal/TimeProviderTest.java | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/core/src/test/java/io/grpc/internal/TimeProviderTest.java b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
index 239379f0dcb..9363c9fa2db 100644
--- a/core/src/test/java/io/grpc/internal/TimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 The gRPC Authors
+ * Copyright 2024 The gRPC Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -36,8 +36,8 @@ public void testCurrentTimeNanos() {
     long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
 
     // Validate the time returned is close to the expected value within a tolerance.
-    long toleranceOfTwoMilliSecond = 2_000_000L; // 2 millisecond tolerance in nanoseconds
+    long toleranceOfTenMilliSecond = 10_000_000L; // 10 millisecond tolerance in nanoseconds
     assertTrue("The current time in nanoseconds should be close to the expected time.",
-        Math.abs(actualTimeNanos - expectedTimeNanos) < toleranceOfTwoMilliSecond);
+        Math.abs(actualTimeNanos - expectedTimeNanos) < toleranceOfTenMilliSecond);
   }
 }

From 32cd4557f2e8b792f60befdae606e5015605d7f4 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Thu, 10 Oct 2024 09:09:07 +0000
Subject: [PATCH 08/27] grpc-core: Fixed Review points

---
 core/src/test/java/io/grpc/internal/TimeProviderTest.java | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/core/src/test/java/io/grpc/internal/TimeProviderTest.java b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
index 9363c9fa2db..d28b88f207e 100644
--- a/core/src/test/java/io/grpc/internal/TimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
@@ -35,9 +35,9 @@ public void testCurrentTimeNanos() {
     Instant instantNow = Instant.now();
     long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
 
-    // Validate the time returned is close to the expected value within a tolerance.
-    long toleranceOfTenMilliSecond = 10_000_000L; // 10 millisecond tolerance in nanoseconds
+    // Validate the time returned is close to the expected value within a tolerance
+    // (i,e 10 millisecond tolerance in nanoseconds).
     assertTrue("The current time in nanoseconds should be close to the expected time.",
-        Math.abs(actualTimeNanos - expectedTimeNanos) < toleranceOfTenMilliSecond);
+        Math.abs(actualTimeNanos - expectedTimeNanos) < 10_000_000L);
   }
 }

From 71ce04041922b03e9d0db9eb1374e1f3442735a7 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Thu, 17 Oct 2024 10:39:03 +0000
Subject: [PATCH 09/27] grpc-core: Fixed Review points

---
 .../main/java/io/grpc/internal/TimeProvider.java  | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index efc22a63777..2199be0f27b 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -16,7 +16,7 @@
 
 package io.grpc.internal;
 
-import java.time.Instant;
+import java.util.concurrent.TimeUnit;
 
 /**
  * Time source representing the current system time in nanos. Used to inject a fake clock
@@ -29,10 +29,15 @@ public interface TimeProvider {
   TimeProvider SYSTEM_TIME_PROVIDER = new TimeProvider() {
     @Override
     public long currentTimeNanos() {
-      Instant instant = Instant.now();
-      int nanos = instant.getNano();
-      long epochSeconds = instant.getEpochSecond();
-      return epochSeconds * 1_000_000_000L + nanos;
+      try {
+        Class<?> instantClass = Class.forName("java.time.Instant");
+        Object instant = instantClass.getMethod("now").invoke(null);
+        int nanos = (int) instantClass.getMethod("getNano").invoke(instant);
+        long epochSeconds = (long) instantClass.getMethod("getEpochSecond").invoke(instant);
+        return epochSeconds * 1_000_000_000L + nanos;
+      } catch (Exception exception) {
+        return TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis());
+      }
     }
   };
 }

From 58073d47f0127724e8fb7a684b7492276c707598 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Thu, 17 Oct 2024 11:26:20 +0000
Subject: [PATCH 10/27] grpc-core: Reverted back to previous changes

---
 .../main/java/io/grpc/internal/TimeProvider.java  | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index 2199be0f27b..efc22a63777 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -16,7 +16,7 @@
 
 package io.grpc.internal;
 
-import java.util.concurrent.TimeUnit;
+import java.time.Instant;
 
 /**
  * Time source representing the current system time in nanos. Used to inject a fake clock
@@ -29,15 +29,10 @@ public interface TimeProvider {
   TimeProvider SYSTEM_TIME_PROVIDER = new TimeProvider() {
     @Override
     public long currentTimeNanos() {
-      try {
-        Class<?> instantClass = Class.forName("java.time.Instant");
-        Object instant = instantClass.getMethod("now").invoke(null);
-        int nanos = (int) instantClass.getMethod("getNano").invoke(instant);
-        long epochSeconds = (long) instantClass.getMethod("getEpochSecond").invoke(instant);
-        return epochSeconds * 1_000_000_000L + nanos;
-      } catch (Exception exception) {
-        return TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis());
-      }
+      Instant instant = Instant.now();
+      int nanos = instant.getNano();
+      long epochSeconds = instant.getEpochSecond();
+      return epochSeconds * 1_000_000_000L + nanos;
     }
   };
 }

From 808b587412d1811048063fd1a8f88d4aad3161cd Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Fri, 18 Oct 2024 12:29:42 +0000
Subject: [PATCH 11/27] core: Fixed the UT as per Review point

---
 core/src/test/java/io/grpc/internal/TimeProviderTest.java | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/core/src/test/java/io/grpc/internal/TimeProviderTest.java b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
index d28b88f207e..a88f490afab 100644
--- a/core/src/test/java/io/grpc/internal/TimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/TimeProviderTest.java
@@ -16,7 +16,7 @@
 
 package io.grpc.internal;
 
-import static org.junit.Assert.assertTrue;
+import static com.google.common.truth.Truth.assertThat;
 
 import java.time.Instant;
 import org.junit.Test;
@@ -37,7 +37,6 @@ public void testCurrentTimeNanos() {
 
     // Validate the time returned is close to the expected value within a tolerance
     // (i,e 10 millisecond tolerance in nanoseconds).
-    assertTrue("The current time in nanoseconds should be close to the expected time.",
-        Math.abs(actualTimeNanos - expectedTimeNanos) < 10_000_000L);
+    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
   }
 }

From 7eee75de7d1b2c503b7a270524a61ef3a1b80bab Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 21 Oct 2024 07:36:43 +0000
Subject: [PATCH 12/27] core: changed the implementation as per the review
 points

---
 .../grpc/internal/ConcurrentTimeProvider.java | 32 ++++++++++++++
 .../io/grpc/internal/InstantTimeProvider.java | 42 +++++++++++++++++++
 .../java/io/grpc/internal/TimeProvider.java   | 12 +-----
 .../internal/TimeProviderResolverFactory.java | 42 +++++++++++++++++++
 ...Test.java => InstantTimeProviderTest.java} |  5 ++-
 5 files changed, 120 insertions(+), 13 deletions(-)
 create mode 100644 core/src/main/java/io/grpc/internal/ConcurrentTimeProvider.java
 create mode 100644 core/src/main/java/io/grpc/internal/InstantTimeProvider.java
 create mode 100644 core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
 rename core/src/test/java/io/grpc/internal/{TimeProviderTest.java => InstantTimeProviderTest.java} (94%)

diff --git a/core/src/main/java/io/grpc/internal/ConcurrentTimeProvider.java b/core/src/main/java/io/grpc/internal/ConcurrentTimeProvider.java
new file mode 100644
index 00000000000..c82a68222b4
--- /dev/null
+++ b/core/src/main/java/io/grpc/internal/ConcurrentTimeProvider.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * {@link ConcurrentTimeProvider} resolves ConcurrentTimeProvider which implements
+ * {@link TimeProvider}.
+ */
+
+final class ConcurrentTimeProvider implements TimeProvider {
+
+  @Override
+  public long currentTimeNanos() {
+    return TimeUnit.MILLISECONDS.toNanos(System.currentTimeMillis());
+  }
+}
diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
new file mode 100644
index 00000000000..12b9196a9a3
--- /dev/null
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+/**
+ * {@link InstantTimeProvider} resolves InstantTimeProvider which implements {@link TimeProvider}.
+ */
+
+final class InstantTimeProvider implements TimeProvider {
+
+  private Class<?> instantClass;
+
+  public InstantTimeProvider(Class<?> instantClass) {
+    this.instantClass = instantClass;
+  }
+
+  @Override
+  public long currentTimeNanos() {
+    try {
+      Object instant = instantClass.getMethod("now").invoke(null);
+      int nanos = (int) instantClass.getMethod("getNano").invoke(instant);
+      long epochSeconds = (long) instantClass.getMethod("getEpochSecond").invoke(instant);
+      return epochSeconds * 1_000_000_000L + nanos;
+    } catch (Exception ex) {
+      throw new RuntimeException(ex);
+    }
+  }
+}
diff --git a/core/src/main/java/io/grpc/internal/TimeProvider.java b/core/src/main/java/io/grpc/internal/TimeProvider.java
index efc22a63777..3bd052ab3e0 100644
--- a/core/src/main/java/io/grpc/internal/TimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/TimeProvider.java
@@ -16,8 +16,6 @@
 
 package io.grpc.internal;
 
-import java.time.Instant;
-
 /**
  * Time source representing the current system time in nanos. Used to inject a fake clock
  * into unit tests.
@@ -26,13 +24,5 @@ public interface TimeProvider {
   /** Returns the current nano time. */
   long currentTimeNanos();
 
-  TimeProvider SYSTEM_TIME_PROVIDER = new TimeProvider() {
-    @Override
-    public long currentTimeNanos() {
-      Instant instant = Instant.now();
-      int nanos = instant.getNano();
-      long epochSeconds = instant.getEpochSecond();
-      return epochSeconds * 1_000_000_000L + nanos;
-    }
-  };
+  TimeProvider SYSTEM_TIME_PROVIDER = TimeProviderResolverFactory.resolveTimeProvider();
 }
diff --git a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
new file mode 100644
index 00000000000..b2553a74e2c
--- /dev/null
+++ b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+/**
+ * {@link TimeProviderResolverFactory} resolves Time providers.
+ */
+
+final class TimeProviderResolverFactory {
+
+  private static final Class INSTANT_CLASS = initInstant();
+
+  private static Class<?> initInstant() {
+    try {
+      return Class.forName("java.time.Instant");
+    } catch (Exception ex) {
+      return null;
+    }
+  }
+
+  static TimeProvider resolveTimeProvider() {
+    if (INSTANT_CLASS == null) {
+      return new ConcurrentTimeProvider();
+    } else {
+      return new InstantTimeProvider(INSTANT_CLASS);
+    }
+  }
+}
diff --git a/core/src/test/java/io/grpc/internal/TimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
similarity index 94%
rename from core/src/test/java/io/grpc/internal/TimeProviderTest.java
rename to core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index a88f490afab..66d76e75d1e 100644
--- a/core/src/test/java/io/grpc/internal/TimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -22,9 +22,10 @@
 import org.junit.Test;
 
 /**
- *  Unit tests for {@link TimeProvider}.
+ * Unit tests for {@link TimeProvider}.
  */
-public class TimeProviderTest {
+public class InstantTimeProviderTest {
+
   @Test
   public void testCurrentTimeNanos() {
 

From 6d59fa1c92b5b12fcaa48c055dec912ddc21a05b Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 21 Oct 2024 07:44:17 +0000
Subject: [PATCH 13/27] core: Fixed checkstyle issue

---
 .../main/java/io/grpc/internal/TimeProviderResolverFactory.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
index b2553a74e2c..ba7d9e83ffc 100644
--- a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
+++ b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
@@ -22,7 +22,7 @@
 
 final class TimeProviderResolverFactory {
 
-  private static final Class INSTANT_CLASS = initInstant();
+  private static final Class<T> INSTANT_CLASS = initInstant();
 
   private static Class<?> initInstant() {
     try {

From a43e9fc6366be5b4e6f3b0f8757745628a7e8ea2 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 21 Oct 2024 07:49:05 +0000
Subject: [PATCH 14/27] core: Fixed checkstyle issue

---
 .../main/java/io/grpc/internal/TimeProviderResolverFactory.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
index ba7d9e83ffc..7ca5a538723 100644
--- a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
+++ b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
@@ -22,7 +22,7 @@
 
 final class TimeProviderResolverFactory {
 
-  private static final Class<T> INSTANT_CLASS = initInstant();
+  private static final Class<?> INSTANT_CLASS = initInstant();
 
   private static Class<?> initInstant() {
     try {

From 04f1c3d22bccf2690ba7d548d07b3d53a9e7da38 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 21 Oct 2024 08:16:44 +0000
Subject: [PATCH 15/27] core: Added junits for the changes

---
 .../internal/InstantTimeProviderTest.java     | 27 +++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 66d76e75d1e..84556186866 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -27,10 +27,33 @@
 public class InstantTimeProviderTest {
 
   @Test
-  public void testCurrentTimeNanos() {
+  public void testInstantCurrentTimeNanos() {
 
+    try {
+      InstantTimeProvider instantTimeProvider = new InstantTimeProvider(
+          Class.forName("java.time.Instant"));
+
+      // Get the current time from the TimeProvider
+      long actualTimeNanos = instantTimeProvider.currentTimeNanos();
+
+      // Get the current time from Instant for comparison
+      Instant instantNow = Instant.now();
+      long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
+
+      // Validate the time returned is close to the expected value within a tolerance
+      // (i,e 10 millisecond tolerance in nanoseconds).
+      assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
+    } catch (ClassNotFoundException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  @Test
+  public void testConcurrentCurrentTimeNanos() {
+
+    ConcurrentTimeProvider concurrentTimeProvider = new ConcurrentTimeProvider();
     // Get the current time from the TimeProvider
-    long actualTimeNanos = TimeProvider.SYSTEM_TIME_PROVIDER.currentTimeNanos();
+    long actualTimeNanos = concurrentTimeProvider.currentTimeNanos();
 
     // Get the current time from Instant for comparison
     Instant instantNow = Instant.now();

From 7d09147a2dbe534b5df24ac140c53e43a4c1263d Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 21 Oct 2024 08:51:13 +0000
Subject: [PATCH 16/27] core: Added annotation for junit class

---
 .../test/java/io/grpc/internal/InstantTimeProviderTest.java  | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 84556186866..6b98b700a98 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -20,10 +20,13 @@
 
 import java.time.Instant;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
 
 /**
- * Unit tests for {@link TimeProvider}.
+ * Unit tests for {@link InstantTimeProvider}.
  */
+@RunWith(JUnit4.class)
 public class InstantTimeProviderTest {
 
   @Test

From 19a44f5bffb1c4ab5aed2a450bc45ab640e3b472 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 21 Oct 2024 10:11:09 +0000
Subject: [PATCH 17/27] okHttp: Code cleanup

---
 .../internal/InstantTimeProviderTest.java     | 33 +++++++++----------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 6b98b700a98..594005333d9 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -30,8 +30,23 @@
 public class InstantTimeProviderTest {
 
   @Test
-  public void testInstantCurrentTimeNanos() {
+  public void testConcurrentCurrentTimeNanos() {
 
+    ConcurrentTimeProvider concurrentTimeProvider = new ConcurrentTimeProvider();
+    // Get the current time from the TimeProvider
+    long actualTimeNanos = concurrentTimeProvider.currentTimeNanos();
+
+    // Get the current time from Instant for comparison
+    Instant instantNow = Instant.now();
+    long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
+
+    // Validate the time returned is close to the expected value within a tolerance
+    // (i,e 10 millisecond tolerance in nanoseconds).
+    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
+  }
+
+  @Test
+  public void testInstantCurrentTimeNanos() {
     try {
       InstantTimeProvider instantTimeProvider = new InstantTimeProvider(
           Class.forName("java.time.Instant"));
@@ -50,20 +65,4 @@ public void testInstantCurrentTimeNanos() {
       throw new RuntimeException(e);
     }
   }
-
-  @Test
-  public void testConcurrentCurrentTimeNanos() {
-
-    ConcurrentTimeProvider concurrentTimeProvider = new ConcurrentTimeProvider();
-    // Get the current time from the TimeProvider
-    long actualTimeNanos = concurrentTimeProvider.currentTimeNanos();
-
-    // Get the current time from Instant for comparison
-    Instant instantNow = Instant.now();
-    long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
-
-    // Validate the time returned is close to the expected value within a tolerance
-    // (i,e 10 millisecond tolerance in nanoseconds).
-    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
-  }
 }

From 1757f995c62cffa7528f59e3b4a9d94b3856334b Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Wed, 23 Oct 2024 09:41:35 +0000
Subject: [PATCH 18/27] core: Fixed the review points

---
 .../io/grpc/internal/InstantTimeProvider.java | 25 +++++++++++++------
 .../internal/InstantTimeProviderTest.java     |  6 ++---
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
index 12b9196a9a3..6d76adae7b8 100644
--- a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -16,25 +16,34 @@
 
 package io.grpc.internal;
 
+import java.lang.reflect.Method;
+import java.util.concurrent.TimeUnit;
+
 /**
  * {@link InstantTimeProvider} resolves InstantTimeProvider which implements {@link TimeProvider}.
  */
-
 final class InstantTimeProvider implements TimeProvider {
-
-  private Class<?> instantClass;
+  private Method now;
+  private Method getNano;
+  private Method getEpochSecond;
 
   public InstantTimeProvider(Class<?> instantClass) {
-    this.instantClass = instantClass;
+    try {
+      this.now = instantClass.getMethod("now");
+      this.getNano = instantClass.getMethod("getNano");
+      this.getEpochSecond = instantClass.getMethod("getEpochSecond");
+    } catch (NoSuchMethodException e) {
+      throw new RuntimeException(e);
+    }
   }
 
   @Override
   public long currentTimeNanos() {
     try {
-      Object instant = instantClass.getMethod("now").invoke(null);
-      int nanos = (int) instantClass.getMethod("getNano").invoke(instant);
-      long epochSeconds = (long) instantClass.getMethod("getEpochSecond").invoke(instant);
-      return epochSeconds * 1_000_000_000L + nanos;
+      Object instant = this.now.invoke(null);
+      int nanos = (int) getNano.invoke(instant);
+      long epochSeconds = (long) getEpochSecond.invoke(instant);
+      return TimeUnit.SECONDS.toNanos(epochSeconds) + nanos;
     } catch (Exception ex) {
       throw new RuntimeException(ex);
     }
diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 594005333d9..c60c68d1493 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -19,6 +19,7 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import java.time.Instant;
+import java.util.concurrent.TimeUnit;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -28,7 +29,6 @@
  */
 @RunWith(JUnit4.class)
 public class InstantTimeProviderTest {
-
   @Test
   public void testConcurrentCurrentTimeNanos() {
 
@@ -38,7 +38,7 @@ public void testConcurrentCurrentTimeNanos() {
 
     // Get the current time from Instant for comparison
     Instant instantNow = Instant.now();
-    long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
+    long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond()) + instantNow.getNano();
 
     // Validate the time returned is close to the expected value within a tolerance
     // (i,e 10 millisecond tolerance in nanoseconds).
@@ -56,7 +56,7 @@ public void testInstantCurrentTimeNanos() {
 
       // Get the current time from Instant for comparison
       Instant instantNow = Instant.now();
-      long expectedTimeNanos = instantNow.getEpochSecond() * 1_000_000_000L + instantNow.getNano();
+      long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond()) + instantNow.getNano();
 
       // Validate the time returned is close to the expected value within a tolerance
       // (i,e 10 millisecond tolerance in nanoseconds).

From b6a91b9b793fd3f0c4cf3329ab8edab185c4001c Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Wed, 23 Oct 2024 09:55:24 +0000
Subject: [PATCH 19/27] core: Fixed checkstyle issue

---
 .../src/main/java/io/grpc/internal/InstantTimeProvider.java | 2 +-
 .../test/java/io/grpc/internal/InstantTimeProviderTest.java | 6 ++++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
index 6d76adae7b8..94fcde3477f 100644
--- a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -40,7 +40,7 @@ public InstantTimeProvider(Class<?> instantClass) {
   @Override
   public long currentTimeNanos() {
     try {
-      Object instant = this.now.invoke(null);
+      Object instant = now.invoke(null);
       int nanos = (int) getNano.invoke(instant);
       long epochSeconds = (long) getEpochSecond.invoke(instant);
       return TimeUnit.SECONDS.toNanos(epochSeconds) + nanos;
diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index c60c68d1493..6dce00b0635 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -38,7 +38,8 @@ public void testConcurrentCurrentTimeNanos() {
 
     // Get the current time from Instant for comparison
     Instant instantNow = Instant.now();
-    long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond()) + instantNow.getNano();
+    long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond())
+        + instantNow.getNano();
 
     // Validate the time returned is close to the expected value within a tolerance
     // (i,e 10 millisecond tolerance in nanoseconds).
@@ -56,7 +57,8 @@ public void testInstantCurrentTimeNanos() {
 
       // Get the current time from Instant for comparison
       Instant instantNow = Instant.now();
-      long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond()) + instantNow.getNano();
+      long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond())
+          + instantNow.getNano();
 
       // Validate the time returned is close to the expected value within a tolerance
       // (i,e 10 millisecond tolerance in nanoseconds).

From 5178e783377d53569d5094cd618e6bbc80a82738 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Wed, 23 Oct 2024 12:03:24 +0000
Subject: [PATCH 20/27] core: Added junit for exception flow

---
 .../grpc/internal/InstantTimeProviderTest.java   | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 6dce00b0635..86a07f0ed56 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -67,4 +67,20 @@ public void testInstantCurrentTimeNanos() {
       throw new RuntimeException(e);
     }
   }
+
+  // Test to verify exception is thrown when "now" method is missing
+  @Test(expected = RuntimeException.class)
+  public void testMissingNowMethodThrowsException() {
+    // Define a class without the "now" method
+    class InvalidInstant {
+      public int getNano() {
+        return 0;
+      }
+      public long getEpochSecond() {
+        return 0L;
+      }
+    }
+    // This should throw a RuntimeException because "now" method is missing
+    new InstantTimeProvider(InvalidInstant.class);
+  }
 }

From 133988bcd83580b7e3024fcb6d7cf5d8282d6cb4 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Wed, 23 Oct 2024 13:22:46 +0000
Subject: [PATCH 21/27] core: Fixed checkstyle issues

---
 .../src/test/java/io/grpc/internal/InstantTimeProviderTest.java | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 86a07f0ed56..e3bac8c58c1 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -76,10 +76,12 @@ class InvalidInstant {
       public int getNano() {
         return 0;
       }
+
       public long getEpochSecond() {
         return 0L;
       }
     }
+
     // This should throw a RuntimeException because "now" method is missing
     new InstantTimeProvider(InvalidInstant.class);
   }

From ee69565b2b236f23ce8a4cdf950e9e1719877168 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Thu, 24 Oct 2024 13:09:35 +0000
Subject: [PATCH 22/27] core: Fixed review points

---
 .../io/grpc/internal/InstantTimeProvider.java |  9 +++-----
 .../internal/TimeProviderResolverFactory.java | 18 ++++-----------
 .../internal/InstantTimeProviderTest.java     | 22 ++-----------------
 3 files changed, 9 insertions(+), 40 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
index 94fcde3477f..b78823d273f 100644
--- a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -16,6 +16,7 @@
 
 package io.grpc.internal;
 
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.concurrent.TimeUnit;
 
@@ -27,14 +28,10 @@ final class InstantTimeProvider implements TimeProvider {
   private Method getNano;
   private Method getEpochSecond;
 
-  public InstantTimeProvider(Class<?> instantClass) {
-    try {
+  public InstantTimeProvider(Class<?> instantClass) throws NoSuchMethodException {
       this.now = instantClass.getMethod("now");
       this.getNano = instantClass.getMethod("getNano");
       this.getEpochSecond = instantClass.getMethod("getEpochSecond");
-    } catch (NoSuchMethodException e) {
-      throw new RuntimeException(e);
-    }
   }
 
   @Override
@@ -44,7 +41,7 @@ public long currentTimeNanos() {
       int nanos = (int) getNano.invoke(instant);
       long epochSeconds = (long) getEpochSecond.invoke(instant);
       return TimeUnit.SECONDS.toNanos(epochSeconds) + nanos;
-    } catch (Exception ex) {
+    } catch (IllegalAccessException | InvocationTargetException ex) {
       throw new RuntimeException(ex);
     }
   }
diff --git a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
index 7ca5a538723..c7e50581292 100644
--- a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
+++ b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
@@ -21,22 +21,12 @@
  */
 
 final class TimeProviderResolverFactory {
-
-  private static final Class<?> INSTANT_CLASS = initInstant();
-
-  private static Class<?> initInstant() {
-    try {
-      return Class.forName("java.time.Instant");
-    } catch (Exception ex) {
-      return null;
-    }
-  }
-
   static TimeProvider resolveTimeProvider() {
-    if (INSTANT_CLASS == null) {
+    try {
+      Class<?> instantClass = Class.forName("java.time.Instant");
+      return new InstantTimeProvider(instantClass);
+    } catch (ClassNotFoundException | NoSuchMethodException ex) {
       return new ConcurrentTimeProvider();
-    } else {
-      return new InstantTimeProvider(INSTANT_CLASS);
     }
   }
 }
diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index e3bac8c58c1..990ebe3e484 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -63,26 +63,8 @@ public void testInstantCurrentTimeNanos() {
       // Validate the time returned is close to the expected value within a tolerance
       // (i,e 10 millisecond tolerance in nanoseconds).
       assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
-    } catch (ClassNotFoundException e) {
-      throw new RuntimeException(e);
+    } catch (ClassNotFoundException | NoSuchMethodException e) {
+      throw new AssertionError();
     }
   }
-
-  // Test to verify exception is thrown when "now" method is missing
-  @Test(expected = RuntimeException.class)
-  public void testMissingNowMethodThrowsException() {
-    // Define a class without the "now" method
-    class InvalidInstant {
-      public int getNano() {
-        return 0;
-      }
-
-      public long getEpochSecond() {
-        return 0L;
-      }
-    }
-
-    // This should throw a RuntimeException because "now" method is missing
-    new InstantTimeProvider(InvalidInstant.class);
-  }
 }

From 00fae975ec5f8ab3ab31fdaaeba04f8f7334823e Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Thu, 24 Oct 2024 13:20:54 +0000
Subject: [PATCH 23/27] core: Fixed review points

---
 .../src/main/java/io/grpc/internal/InstantTimeProvider.java | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
index b78823d273f..53c57892450 100644
--- a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -29,9 +29,9 @@ final class InstantTimeProvider implements TimeProvider {
   private Method getEpochSecond;
 
   public InstantTimeProvider(Class<?> instantClass) throws NoSuchMethodException {
-      this.now = instantClass.getMethod("now");
-      this.getNano = instantClass.getMethod("getNano");
-      this.getEpochSecond = instantClass.getMethod("getEpochSecond");
+    this.now = instantClass.getMethod("now");
+    this.getNano = instantClass.getMethod("getNano");
+    this.getEpochSecond = instantClass.getMethod("getEpochSecond");
   }
 
   @Override

From f4abffc6b2716cd782eb5806945f0103e8bf57f4 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Fri, 25 Oct 2024 06:51:40 +0000
Subject: [PATCH 24/27] core: Fixed review points

---
 .../internal/ConcurrentTimeProviderTest.java  | 48 +++++++++++++++++++
 .../internal/InstantTimeProviderTest.java     | 28 ++---------
 2 files changed, 52 insertions(+), 24 deletions(-)
 create mode 100644 core/src/test/java/io/grpc/internal/ConcurrentTimeProviderTest.java

diff --git a/core/src/test/java/io/grpc/internal/ConcurrentTimeProviderTest.java b/core/src/test/java/io/grpc/internal/ConcurrentTimeProviderTest.java
new file mode 100644
index 00000000000..a02cb6a6e42
--- /dev/null
+++ b/core/src/test/java/io/grpc/internal/ConcurrentTimeProviderTest.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2024 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.internal;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.time.Instant;
+import java.util.concurrent.TimeUnit;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Unit tests for {@link ConcurrentTimeProvider}.
+ */
+@RunWith(JUnit4.class)
+public class ConcurrentTimeProviderTest {
+  @Test
+  public void testConcurrentCurrentTimeNanos() {
+
+    ConcurrentTimeProvider concurrentTimeProvider = new ConcurrentTimeProvider();
+    // Get the current time from the ConcurrentTimeProvider
+    long actualTimeNanos = concurrentTimeProvider.currentTimeNanos();
+
+    // Get the current time from Instant for comparison
+    Instant instantNow = Instant.now();
+    long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond())
+        + instantNow.getNano();
+
+    // Validate the time returned is close to the expected value within a tolerance
+    // (i,e 10 millisecond tolerance in nanoseconds).
+    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
+  }
+}
diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 990ebe3e484..5675e6086b2 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -30,29 +30,12 @@
 @RunWith(JUnit4.class)
 public class InstantTimeProviderTest {
   @Test
-  public void testConcurrentCurrentTimeNanos() {
+  public void testInstantCurrentTimeNanos() throws Exception {
 
-    ConcurrentTimeProvider concurrentTimeProvider = new ConcurrentTimeProvider();
-    // Get the current time from the TimeProvider
-    long actualTimeNanos = concurrentTimeProvider.currentTimeNanos();
+    InstantTimeProvider instantTimeProvider = new InstantTimeProvider(
+        Class.forName("java.time.Instant"));
 
-    // Get the current time from Instant for comparison
-    Instant instantNow = Instant.now();
-    long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond())
-        + instantNow.getNano();
-
-    // Validate the time returned is close to the expected value within a tolerance
-    // (i,e 10 millisecond tolerance in nanoseconds).
-    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
-  }
-
-  @Test
-  public void testInstantCurrentTimeNanos() {
-    try {
-      InstantTimeProvider instantTimeProvider = new InstantTimeProvider(
-          Class.forName("java.time.Instant"));
-
-      // Get the current time from the TimeProvider
+      // Get the current time from the InstantTimeProvider
       long actualTimeNanos = instantTimeProvider.currentTimeNanos();
 
       // Get the current time from Instant for comparison
@@ -63,8 +46,5 @@ public void testInstantCurrentTimeNanos() {
       // Validate the time returned is close to the expected value within a tolerance
       // (i,e 10 millisecond tolerance in nanoseconds).
       assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
-    } catch (ClassNotFoundException | NoSuchMethodException e) {
-      throw new AssertionError();
-    }
   }
 }

From 09fb4742da779e581fd68ca3ffc972ee2aa1fc00 Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Fri, 25 Oct 2024 07:07:57 +0000
Subject: [PATCH 25/27] core: Fixed checkstyle issues

---
 .../grpc/internal/InstantTimeProviderTest.java   | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
index 5675e6086b2..ef97d374b10 100644
--- a/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
+++ b/core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java
@@ -35,16 +35,16 @@ public void testInstantCurrentTimeNanos() throws Exception {
     InstantTimeProvider instantTimeProvider = new InstantTimeProvider(
         Class.forName("java.time.Instant"));
 
-      // Get the current time from the InstantTimeProvider
-      long actualTimeNanos = instantTimeProvider.currentTimeNanos();
+    // Get the current time from the InstantTimeProvider
+    long actualTimeNanos = instantTimeProvider.currentTimeNanos();
 
-      // Get the current time from Instant for comparison
-      Instant instantNow = Instant.now();
-      long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond())
+    // Get the current time from Instant for comparison
+    Instant instantNow = Instant.now();
+    long expectedTimeNanos = TimeUnit.SECONDS.toNanos(instantNow.getEpochSecond())
           + instantNow.getNano();
 
-      // Validate the time returned is close to the expected value within a tolerance
-      // (i,e 10 millisecond tolerance in nanoseconds).
-      assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
+    // Validate the time returned is close to the expected value within a tolerance
+    // (i,e 10 millisecond tolerance in nanoseconds).
+    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
   }
 }

From b24dd90b22825b66271e50b334eba176ddb0cd7a Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 28 Oct 2024 07:58:05 +0000
Subject: [PATCH 26/27] core: Fixed recent review points

---
 core/src/main/java/io/grpc/internal/InstantTimeProvider.java  | 4 +++-
 .../java/io/grpc/internal/TimeProviderResolverFactory.java    | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
index 53c57892450..3061d06ae3b 100644
--- a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -16,6 +16,8 @@
 
 package io.grpc.internal;
 
+import static com.google.common.math.LongMath.saturatedAdd;
+
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.concurrent.TimeUnit;
@@ -40,7 +42,7 @@ public long currentTimeNanos() {
       Object instant = now.invoke(null);
       int nanos = (int) getNano.invoke(instant);
       long epochSeconds = (long) getEpochSecond.invoke(instant);
-      return TimeUnit.SECONDS.toNanos(epochSeconds) + nanos;
+      return saturatedAdd(TimeUnit.SECONDS.toNanos(epochSeconds), nanos);
     } catch (IllegalAccessException | InvocationTargetException ex) {
       throw new RuntimeException(ex);
     }
diff --git a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
index c7e50581292..da11bc07d04 100644
--- a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
+++ b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
@@ -25,8 +25,10 @@ static TimeProvider resolveTimeProvider() {
     try {
       Class<?> instantClass = Class.forName("java.time.Instant");
       return new InstantTimeProvider(instantClass);
-    } catch (ClassNotFoundException | NoSuchMethodException ex) {
+    } catch (ClassNotFoundException ex) {
       return new ConcurrentTimeProvider();
+    } catch (NoSuchMethodException ex) {
+      throw new AssertionError(ex);
     }
   }
 }

From d637a36f42452bc0ac5baf61255123e444206a0e Mon Sep 17 00:00:00 2001
From: vinodhabib <vinodhabib@gmail.com>
Date: Mon, 28 Oct 2024 10:24:18 +0000
Subject: [PATCH 27/27] core: Fixed recent review points

---
 .../java/io/grpc/internal/InstantTimeProvider.java   | 12 ++++++++----
 .../grpc/internal/TimeProviderResolverFactory.java   |  2 --
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
index 3061d06ae3b..38c840d2594 100644
--- a/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
+++ b/core/src/main/java/io/grpc/internal/InstantTimeProvider.java
@@ -30,10 +30,14 @@ final class InstantTimeProvider implements TimeProvider {
   private Method getNano;
   private Method getEpochSecond;
 
-  public InstantTimeProvider(Class<?> instantClass) throws NoSuchMethodException {
-    this.now = instantClass.getMethod("now");
-    this.getNano = instantClass.getMethod("getNano");
-    this.getEpochSecond = instantClass.getMethod("getEpochSecond");
+  public InstantTimeProvider(Class<?> instantClass) {
+    try {
+      this.now = instantClass.getMethod("now");
+      this.getNano = instantClass.getMethod("getNano");
+      this.getEpochSecond = instantClass.getMethod("getEpochSecond");
+    } catch (NoSuchMethodException ex) {
+      throw new AssertionError(ex);
+    }
   }
 
   @Override
diff --git a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
index da11bc07d04..d88d9bb9eb5 100644
--- a/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
+++ b/core/src/main/java/io/grpc/internal/TimeProviderResolverFactory.java
@@ -27,8 +27,6 @@ static TimeProvider resolveTimeProvider() {
       return new InstantTimeProvider(instantClass);
     } catch (ClassNotFoundException ex) {
       return new ConcurrentTimeProvider();
-    } catch (NoSuchMethodException ex) {
-      throw new AssertionError(ex);
     }
   }
 }