tanmayrauth commented on code in PR #1430: URL: https://github.com/apache/iceberg-go/pull/1430#discussion_r3581379038
########## metrics/registry.go: ########## @@ -0,0 +1,104 @@ +// 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. + +package metrics + +import ( + "fmt" + "sync" +) + +// ReporterImplKey is the catalog/table property that selects a registered +// reporter by name (e.g. "logging"). It is the Go analogue of Java's +// metrics-reporter-impl; Go uses a name→factory registry rather than +// reflection over a class name. +const ReporterImplKey = "metrics-reporter-impl" + +// Built-in reporter names usable as the value of [ReporterImplKey]. +const ( + ReporterNameNop = "nop" + ReporterNameLogging = "logging" +) + +// Factory builds a Reporter from configuration properties. The same property +// map that selected the reporter is passed in, so a factory may read its own +// configuration keys. +type Factory func(props map[string]string) (Reporter, error) + +var ( + registryMu sync.RWMutex + registry = map[string]Factory{} +) + +func init() { + Register(ReporterNameNop, func(map[string]string) (Reporter, error) { return NopReporter{}, nil }) + Register(ReporterNameLogging, func(map[string]string) (Reporter, error) { + return NewLoggingReporter(nil), nil + }) +} + +// Register makes a reporter factory available under name. It panics if name is +// empty or already registered, mirroring database/sql.Register — registration +// is expected to happen once, from package init. +func Register(name string, factory Factory) { + if name == "" { + panic("metrics: Register called with empty name") + } + if factory == nil { + panic("metrics: Register called with nil factory") + } + registryMu.Lock() + defer registryMu.Unlock() + if _, dup := registry[name]; dup { + panic("metrics: Register called twice for " + name) + } + registry[name] = factory +} + +// Deregister removes a previously registered reporter factory. It is a no-op if +// name is not registered. This exists primarily so tests can register a factory +// and undo it via t.Cleanup, keeping the process-global registry re-runnable +// under go test -count=N. +func Deregister(name string) { Review Comment: Guarded rather than just documented — Deregister is now a no-op for nop and logging, with the reasoning in the godoc (since Register panics on duplicates, a removed built-in could never be restored). I added TestDeregisterProtectsBuiltins so both stay resolvable after a Deregister attempt. -- 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]
