BenEddy commented on code in PR #1820: URL: https://github.com/apache/cassandra-gocql-driver/pull/1820#discussion_r1866728349
########## example_interceptor_test.go: ########## @@ -0,0 +1,88 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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. + */ +/* + * Content before git sha 34fdeebefcbf183ed7f916f931aa0586fdaa1b40 + * Copyright (c) 2016, The Gocql authors, + * provided under the BSD-3-Clause License. + * See the NOTICE file distributed with this work for additional information. + */ + +package gocql_test + +import ( + "context" + "log" + "time" + + gocql "github.com/gocql/gocql" +) + +type MyQueryAttemptInterceptor struct { + injectFault bool +} + +func (q MyQueryAttemptInterceptor) Intercept( + ctx context.Context, + attempt gocql.QueryAttempt, + handler gocql.QueryAttemptHandler, +) (*gocql.Iter, error) { + switch q := attempt.Query.(type) { + case *gocql.Query: + // Inspect or modify query + attempt.Query = q + case *gocql.Batch: + // Inspect or modify batch + attempt.Query = q + } + + // Inspect or modify context + ctx = context.WithValue(ctx, "trace-id", "123") + + // Optionally bypass the handler and return an error to prevent query execution. + // For example, to simulate query timeouts. + if q.injectFault && attempt.Attempts == 0 { + <-time.After(1 * time.Second) + return nil, gocql.RequestErrWriteTimeout{} + } + + // The interceptor *must* invoke the handler to execute the query. + return handler(ctx, attempt), nil +} + +// Example_interceptor demonstrates how to implement a QueryAttemptInterceptor. +func Example_interceptor() { + cluster := gocql.NewCluster("localhost:9042") + cluster.QueryAttemptInterceptor = MyQueryAttemptInterceptor{injectFault: true} + + session, err := cluster.CreateSession() + if err != nil { + log.Fatal(err) + } + defer session.Close() + + ctx := context.Background() + + var stringValue string + err = session.Query("select now() from system.local"). + WithContext(ctx). + RetryPolicy(&gocql.SimpleRetryPolicy{NumRetries: 2}). + Scan(&stringValue) + if err != nil { Review Comment: Not strongly opposed, but I'd favor using the query `context` to selectively enable an interceptor because it avoids introducing potential conflicts between a session-level interceptor config and query-level interceptor config. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
