feat: move session lastUseTime parameter from PooledSession to SessionImpl class. Fix updation of the parameter for chained RPCs within one transaction.

google-cloud-spanner/src/main/java/com/google/cloud/spanner/AbstractReadContext.java

@@ -73,6 +73,8 @@ abstract static class Builder<B extends Builder<?, T>, T extends AbstractReadCon
     private QueryOptions defaultQueryOptions = SpannerOptions.Builder.DEFAULT_QUERY_OPTIONS;
     private ExecutorProvider executorProvider;
 
+    private Clock clock;
+
     Builder() {}
 
     @SuppressWarnings("unchecked")
@@ -110,6 +112,11 @@ B setExecutorProvider(ExecutorProvider executorProvider) {
       return self();
     }
 
+    B setClock(Clock clock) {
+      this.clock = clock;
+      return self();
+    }
+
     abstract T build();
   }
 
@@ -392,6 +399,8 @@ void initTransaction() {
   private final int defaultPrefetchChunks;
   private final QueryOptions defaultQueryOptions;
 
+  private final Clock clock;
+
   @GuardedBy("lock")
   private boolean isValid = true;
 
@@ -416,6 +425,7 @@ void initTransaction() {
     this.defaultQueryOptions = builder.defaultQueryOptions;
     this.span = builder.span;
     this.executorProvider = builder.executorProvider;
+    this.clock = builder.clock == null ? new Clock() : builder.clock;
   }
 
   @Override
@@ -826,6 +836,7 @@ CloseableIterator<PartialResultSet> startStream(@Nullable ByteString resumeToken
             SpannerRpc.StreamingCall call =
                 rpc.read(
                     builder.build(), stream.consumer(), session.getOptions(), isRouteToLeader());
+            session.markUsed(clock.instant());
             call.request(prefetchChunks);
             stream.setCall(call, /* withBeginTransaction = */ builder.getTransaction().hasBegin());
             return stream;

google-cloud-spanner/src/main/java/com/google/cloud/spanner/Clock.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2023 Google LLC
+ *
+ * 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 com.google.cloud.spanner;
+
+import org.threeten.bp.Instant;
+
+/**
+ * Wrapper around current time so that we can fake it in tests. TODO(user): Replace with Java 8
+ * Clock.
+ */
+class Clock {
+  Instant instant() {
+    return Instant.now();
+  }
+}

google-cloud-spanner/src/main/java/com/google/cloud/spanner/SessionImpl.java

@@ -53,6 +53,7 @@
 import java.util.Map;
 import java.util.concurrent.ExecutionException;
 import javax.annotation.Nullable;
+import org.threeten.bp.Instant;
 
 /**
  * Implementation of {@link Session}. Sessions are managed internally by the client library, and
@@ -98,12 +99,14 @@ interface SessionTransaction {
   ByteString readyTransactionId;
   private final Map<SpannerRpc.Option, ?> options;
   private Span currentSpan;
+  private volatile Instant lastUseTime;
 
   SessionImpl(SpannerImpl spanner, String name, Map<SpannerRpc.Option, ?> options) {
     this.spanner = spanner;
     this.options = options;
     this.name = checkNotNull(name);
     this.databaseId = SessionId.of(name).getDatabaseId();
+    this.lastUseTime = Instant.now();
   }
 
   @Override
@@ -123,6 +126,14 @@ Span getCurrentSpan() {
     return currentSpan;
   }
 
+  Instant getLastUseTime() {
+    return lastUseTime;
+  }
+
+  void markUsed(Instant instant) {
+    lastUseTime = instant;
+  }
+
   @Override
   public long executePartitionedUpdate(Statement stmt, UpdateOption... options) {
     setActive(null);
@@ -385,6 +396,10 @@ ApiFuture<ByteString> beginTransactionAsync(Options transactionOptions, boolean
   }
 
   TransactionContextImpl newTransaction(Options options) {
+    final Clock clock =
+        spanner.getOptions().getSessionPoolOptions() != null
+            ? spanner.getOptions().getSessionPoolOptions().getPoolMaintainerClock()
+            : null;
     return TransactionContextImpl.newBuilder()
         .setSession(this)
         .setOptions(options)
@@ -396,6 +411,7 @@ TransactionContextImpl newTransaction(Options options) {
         .setDefaultPrefetchChunks(spanner.getDefaultPrefetchChunks())
         .setSpan(currentSpan)
         .setExecutorProvider(spanner.getAsyncExecutorProvider())
+        .setClock(clock)
         .build();
   }