用于 Gremlin 服务器响应标头的 Azure Cosmos DB

本文介绍 Azure Cosmos DB for Gremlin 服务器在请求执行时返回到调用方标头。 这些标头可用于排查请求性能问题，构建与 Azure Cosmos DB 服务本机集成的应用程序并简化客户支持。

请记住，依赖于这些标头，可将应用程序的可移植性限制为其他 Gremlin 实现。 回报是，你将获得更紧密的与用于 Gremlin 的 Azure Cosmos DB 的集成。 这些标头不是 TinkerPop 标准。

Headers

状态代码

下面列出了服务器为状态属性返回 x-ms-status-code 的最常见代码。

Samples

基于读取一个状态属性 Gremlin.Net 的示例客户端应用程序：

// Following example reads a status code and total request charge from server response attributes.
// Variable "server" is assumed to be assigned to an instance of a GremlinServer that is connected to Azure Cosmos DB account.
using (GremlinClient client = new GremlinClient(server, new GraphSON2Reader(), new GraphSON2Writer(), GremlinClient.GraphSON2MimeType))
{
  ResultSet<dynamic> responseResultSet = await GremlinClientExtensions.SubmitAsync<dynamic>(client, requestScript: "g.V().count()");
  long statusCode = (long)responseResultSet.StatusAttributes["x-ms-status-code"];
  double totalRequestCharge = (double)responseResultSet.StatusAttributes["x-ms-total-request-charge"];

  // Status code and request charge are logged into application telemetry.
}

演示如何从 Gremlin Java 客户端读取状态属性的示例：

try {
  ResultSet resultSet = this.client.submit("g.addV().property('id', '13')");
  List<Result> results = resultSet.all().get();

  // Process and consume results

} catch (ResponseException re) {
  // Check for known errors that need to be retried or skipped
  if (re.getStatusAttributes().isPresent()) {
    Map<String, Object> attributes = re.getStatusAttributes().get();
    int statusCode = (int) attributes.getOrDefault("x-ms-status-code", -1);

    // Now we can check for specific conditions
    if (statusCode == 409) {
        // Handle conflicting writes
      }
    }

    // Check if we need to delay retry
    if (attributes.containsKey("x-ms-retry-after-ms")) {
      // Read the value of the attribute as is
      String retryAfterTimeSpan = (String) attributes.get("x-ms-retry-after-ms"));

      // Convert the value into actionable duration
			LocalTime locaTime = LocalTime.parse(retryAfterTimeSpan);
			Duration duration = Duration.between(LocalTime.MIN, locaTime);

      // Perform a retry after "duration" interval of time has elapsed
    }
  }
}