feat: add connection worker skeleton used for multiplexing client

.github/.OwlBot.yaml

@@ -78,6 +78,7 @@ deep-preserve-regex:
 - "/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1.*/Waiter.java"
 - "/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/Exceptions.java"
 - "/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorker.java"
+- "/google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerPool.java"
 
 deep-copy-regex:
 - source: "/google/cloud/bigquery/storage/(v.*)/.*-java/proto-google-.*/src"

google-cloud-bigquerystorage/pom.xml

@@ -44,6 +44,15 @@
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>flatten-maven-plugin</artifactId>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-dependency-plugin</artifactId>
+        <configuration>
+          <usedDependencies>
+            <dependency>com.google.auto.value:auto-value</dependency>
+          </usedDependencies>
+        </configuration>
+      </plugin>
     </plugins>
   </build>
   <dependencies>
@@ -63,6 +72,16 @@
       <groupId>com.google.api</groupId>
       <artifactId>api-common</artifactId>
     </dependency>
+    <dependency>
+      <groupId>com.google.auto.value</groupId>
+      <artifactId>auto-value</artifactId>
+      <version>1.9</version>
+    </dependency>
+    <dependency>
+      <groupId>com.google.auto.value</groupId>
+      <artifactId>auto-value-annotations</artifactId>
+      <version>1.9</version>
+    </dependency>
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
@@ -71,7 +90,6 @@
       <groupId>com.google.api.grpc</groupId>
       <artifactId>proto-google-common-protos</artifactId>
     </dependency>
-
     <dependency>
       <groupId>com.google.api.grpc</groupId>
       <artifactId>proto-google-cloud-bigquerystorage-v1beta1</artifactId>
@@ -134,7 +152,6 @@
       <artifactId>junit</artifactId>
       <scope>test</scope>
     </dependency>
-
     <dependency>
       <groupId>com.google.truth</groupId>
       <artifactId>truth</artifactId>

google-cloud-bigquerystorage/src/main/java/com/google/cloud/bigquery/storage/v1/ConnectionWorkerPool.java

@@ -0,0 +1,176 @@
+/*
+ * Copyright 2022 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
+ *
+ *     https://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.bigquery.storage.v1;
+
+import com.google.api.core.ApiFuture;
+import com.google.api.gax.batching.FlowController;
+import com.google.auto.value.AutoValue;
+import javax.annotation.concurrent.GuardedBy;
+
+public class ConnectionWorkerPool {
+  /*
+   * Max allowed inflight requests in the stream. Method append is blocked at this.
+   */
+  private final long maxInflightRequests;
+
+  /*
+   * Max allowed inflight bytes in the stream. Method append is blocked at this.
+   */
+  private final long maxInflightBytes;
+
+  /*
+   * Behavior when inflight queue is exceeded. Only supports Block or Throw, default is Block.
+   */
+  private final FlowController.LimitExceededBehavior limitExceededBehavior;
+
+  /*
+   * TraceId for debugging purpose.
+   */
+  private final String traceId;
+
+  /*
+   * Tracks current inflight requests in the stream.
+   */
+  @GuardedBy("lock")
+  private long inflightRequests = 0;
+
+  /*
+   * Tracks current inflight bytes in the stream.
+   */
+  @GuardedBy("lock")
+  private long inflightBytes = 0;
+
+  /*
+   * Tracks how often the stream was closed due to a retriable error. Streaming will stop when the
+   * count hits a threshold. Streaming should only be halted, if it isn't possible to establish a
+   * connection. Keep track of the number of reconnections in succession. This will be reset if
+   * a row is successfully called back.
+   */
+  @GuardedBy("lock")
+  private long conectionRetryCountWithoutCallback = 0;
+
+  /*
+   * If false, streamConnection needs to be reset.
+   */
+  @GuardedBy("lock")
+  private boolean streamConnectionIsConnected = false;
+
+  /*
+   * A boolean to track if we cleaned up inflight queue.
+   */
+  @GuardedBy("lock")
+  private boolean inflightCleanuped = false;
+
+  /*
+   * Indicates whether user has called Close() or not.
+   */
+  @GuardedBy("lock")
+  private boolean userClosed = false;
+
+  /*
+   * The final status of connection. Set to nonnull when connection is permanently closed.
+   */
+  @GuardedBy("lock")
+  private Throwable connectionFinalStatus = null;
+
+  /*
+   * Contains the updated TableSchema.
+   */
+  @GuardedBy("lock")
+  private TableSchema updatedSchema;
+
+  /*
+   * A client used to interact with BigQuery.
+   */
+  private BigQueryWriteClient client;
+
+  /*
+   * If true, the client above is created by this writer and should be closed.
+   */
+  private boolean ownsBigQueryWriteClient = false;
+
+  /** Settings for connection pool. */
+  @AutoValue
+  public abstract static class Settings {
+    /**
+     * The minimum connections each pool created before trying to reuse the previously created
+     * connection in multiplexing mode.
+     */
+    abstract int minConnectionsPerPool();
+
+    /** The maximum connections per connection pool. */
+    abstract int maxConnectionsPerPool();
+
+    public static Builder builder() {
+      return new AutoValue_ConnectionWorkerPool_Settings.Builder()
+          .setMinConnectionsPerPool(2)
+          .setMaxConnectionsPerPool(10);
+    }
+
+    /** Builder for the options to config {@link ConnectionWorkerPool}. */
+    @AutoValue.Builder
+    public abstract static class Builder {
+      public abstract Builder setMinConnectionsPerPool(int value);
+
+      public abstract Builder setMaxConnectionsPerPool(int value);
+
+      public abstract Settings build();
+    }
+  }
+
+  /** Static setting for connection pool. */
+  private static Settings settings = Settings.builder().build();
+
+  public ConnectionWorkerPool(
+      long maxInflightRequests,
+      long maxInflightBytes,
+      FlowController.LimitExceededBehavior limitExceededBehavior,
+      String traceId,
+      BigQueryWriteClient client,
+      boolean ownsBigQueryWriteClient) {
+    this.maxInflightRequests = maxInflightRequests;
+    this.maxInflightBytes = maxInflightBytes;
+    this.limitExceededBehavior = limitExceededBehavior;
+    this.traceId = traceId;
+    this.client = client;
+    this.ownsBigQueryWriteClient = ownsBigQueryWriteClient;
+  }
+
+  /**
+   * Sets static connection pool options.
+   *
+   * <p>Note: this method should be triggered prior to the construction of connection pool.
+   */
+  public static void setOptions(Settings settings) {
+    ConnectionWorkerPool.settings = settings;
+  }
+
+  /** Distributes the writing of a message to an underlying connection. */
+  public ApiFuture<AppendRowsResponse> append(StreamWriter streamWriter, ProtoRows rows) {
+    throw new RuntimeException("Append is not implemented!");
+  }
+
+  /** Distributes the writing of a message to an underlying connection. */
+  public ApiFuture<AppendRowsResponse> append(
+      StreamWriter streamWriter, ProtoRows rows, long offset) {
+    throw new RuntimeException("append with offset is not implemented on connection pool!");
+  }
+
+  /** Close the stream writer. Shut down all resources. */
+  public void close(StreamWriter streamWriter) {
+    throw new RuntimeException("close is implemented on connection pool");
+  }
+}