Mengonfigurasi waktu tunggu pernyataan

Halaman ini menjelaskan cara menetapkan waktu tunggu untuk satu eksekusi pernyataan menggunakan library klien Spanner. Hal ini dapat digunakan untuk mengganti konfigurasi waktu tunggu default library klien. Pernyataan gagal dengan error DEADLINE_EXCEEDED jika pernyataan tidak dapat diselesaikan dalam nilai waktu tunggu yang ditentukan.

Catatan: Mungkin saja waktu tunggu terjadi setelah pernyataan selesai dijalankan di Spanner, tetapi sebelum respons mencapai klien. Dalam hal ini, pernyataan mungkin berhasil di-commit ke Spanner.

Contoh ini menunjukkan cara menetapkan waktu tunggu untuk satu eksekusi pernyataan di library klien Cloud Spanner.

Go

import (
	"context"
	"fmt"
	"io"
	"time"

	"cloud.google.com/go/spanner"
	"google.golang.org/grpc/codes"
)

func setStatementTimeout(w io.Writer, db string) error {
	client, err := spanner.NewClient(context.Background(), db)
	if err != nil {
		return err
	}
	defer client.Close()

	_, err = client.ReadWriteTransaction(context.Background(),
		func(ctx context.Context, txn *spanner.ReadWriteTransaction) error {
			// Create a context with a 60-second timeout and apply this timeout to the insert statement.
			ctxWithTimeout, cancel := context.WithTimeout(context.Background(), 60*time.Second)
			defer cancel()
			stmt := spanner.Statement{
				SQL: `INSERT Singers (SingerId, FirstName, LastName)
					VALUES (39, 'George', 'Washington')`,
			}
			rowCount, err := txn.Update(ctxWithTimeout, stmt)
			// Get the error code from the error. This function returns codes.OK if err == nil.
			code := spanner.ErrCode(err)
			if code == codes.DeadlineExceeded {
				fmt.Fprintf(w, "Insert statement timed out.\n")
			} else if code == codes.OK {
				fmt.Fprintf(w, "%d record(s) inserted.\n", rowCount)
			} else {
				fmt.Fprintf(w, "Insert statement failed with error %v\n", err)
			}
			return err
		})
	if err != nil {
		return err
	}
	return nil
}

Java

static void executeSqlWithTimeout() {
  // TODO(developer): Replace these variables before running the sample.
  String projectId = "my-project";
  String instanceId = "my-instance";
  String databaseId = "my-database";

  try (Spanner spanner =
      SpannerOptions.newBuilder().setProjectId(projectId).build().getService()) {
    DatabaseClient client =
        spanner.getDatabaseClient(DatabaseId.of(projectId, instanceId, databaseId));
    executeSqlWithTimeout(client);
  }
}

static void executeSqlWithTimeout(DatabaseClient client) {
  CallContextConfigurator configurator = new CallContextConfigurator() {
    public <ReqT, RespT> ApiCallContext configure(ApiCallContext context, ReqT request,
        MethodDescriptor<ReqT, RespT> method) {
      // DML uses the ExecuteSql RPC.
      if (method == SpannerGrpc.getExecuteSqlMethod()) {
        // NOTE: You can use a GrpcCallContext to set a custom timeout for a single RPC
        // invocation. This timeout can however ONLY BE SHORTER than the default timeout
        // for the RPC. If you set a timeout that is longer than the default timeout, then
        // the default timeout will be used.
        return GrpcCallContext.createDefault()
            .withCallOptions(CallOptions.DEFAULT.withDeadlineAfter(60L, TimeUnit.SECONDS));
      }
      // Return null to indicate that the default should be used for other methods.
      return null;
    }
  };
  // Create a context that uses the custom call configuration.
  Context context =
      Context.current().withValue(SpannerOptions.CALL_CONTEXT_CONFIGURATOR_KEY, configurator);
  // Run the transaction in the custom context.
  context.run(() ->
      client.readWriteTransaction().<long[]>run(transaction -> {
        String sql = "INSERT INTO Singers (SingerId, FirstName, LastName)\n"
            + "VALUES (20, 'George', 'Washington')";
        long rowCount = transaction.executeUpdate(Statement.of(sql));
        System.out.printf("%d record inserted.%n", rowCount);
        return null;
      })
  );
}