zeroshade commented on code in PR #244: URL: https://github.com/apache/iceberg-go/pull/244#discussion_r1906136606
########## catalog/registry.go: ########## @@ -0,0 +1,135 @@ +// 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 catalog + +import ( + "fmt" + "maps" + "net/url" + "slices" + "strings" + "sync" + + "github.com/apache/iceberg-go" +) + +type registry map[string]Registrar + +func (r registry) getKeys() []string { + regMutex.Lock() + defer regMutex.Unlock() + return slices.Collect(maps.Keys(r)) +} + +func (r registry) set(catalogType string, reg Registrar) { + regMutex.Lock() + defer regMutex.Unlock() + r[catalogType] = reg +} + +func (r registry) get(catalogType string) (Registrar, bool) { + regMutex.Lock() + defer regMutex.Unlock() + reg, ok := r[catalogType] + return reg, ok +} + +func (r registry) remove(catalogType string) { + regMutex.Lock() + defer regMutex.Unlock() + delete(r, catalogType) +} + +var ( + regMutex sync.Mutex + defaultRegistry = registry{} +) + +// Registrar is a factory for creating Catalog instances, used for registering to use +// with LoadCatalog. +type Registrar interface { + GetCatalog(catalogURI string, props iceberg.Properties) (Catalog, error) +} + +type RegistrarFunc func(string, iceberg.Properties) (Catalog, error) + +func (f RegistrarFunc) GetCatalog(catalogURI string, props iceberg.Properties) (Catalog, error) { + return f(catalogURI, props) +} + +// Register adds the new catalog type to the registry. If the catalog type is already registered, it will be replaced. +func Register(catalogType string, reg Registrar) { + if reg == nil { + panic("catalog: RegisterCatalog catalog factory is nil") + } + defaultRegistry.set(catalogType, reg) +} + +// Unregister removes the requested catalog factory from the registry. +func Unregister(catalogType string) { + defaultRegistry.remove(catalogType) +} + +// GetRegsisteredCatalogs returns the list of registered catalog names that can +// be looked up via LoadCatalog. +func GetRegisteredCatalogs() []string { + return defaultRegistry.getKeys() +} + +// Load allows loading a specific catalog by URI and properties. +// +// This is utilized alongside RegisterCatalog/UnregisterCatalog to not only allow +// easier catalog loading but also to allow for custom catalog implementations to +// be registered and loaded external to this module. +// +// The URI is used to determine the catalog type by first checking if it contains +// the string "://" indicating the presence of a scheme. If so, the schema is used +// to lookup the registered catalog. i.e. "glue://..." would return the Glue catalog +// implementation, passing the URI and properties to NewGlueCatalog. If no scheme is +// present, then the URI is used as-is to lookup the catalog factory function. +// +// Currently the following catalogs are registered by default: +// +// - "glue" for AWS Glue Data Catalog, the rest of the URI is ignored, all configuration +// should be provided using the properties. "glue.region", "glue.endpoint", +// "glue.max-retries", etc. Default AWS credentials are used if found, or can be +// overridden by setting "glue.access-key", "glue.secret-access-key", and "glue.session-token". +// +// - "rest" for a REST API catalog, if the properties have a "uri" key, then that will be used +// as the REST endpoint, otherwise the URI is used as the endpoint. The REST catalog also +// registers "http" and "https" so that Load with an http/s URI will automatically +// load the REST Catalog. +func Load(catalogURI string, props iceberg.Properties) (Catalog, error) { Review Comment: That is supported in this structure (unless I'm missing something) calling `Load` will ultimately call `GetCatalog` on the Registered factory, creating a *new* catalog instance each time you call `catalog.Load` i.e.: you can call `catalog.Load("rest", iceberg.Properties{"uri": "http://foobar"})` and `catalog.Load("http://foobarbaz";, nil)` and you'll get two *different* rest catalog instances each using their appropriate endpoint. The distinction is that we allow simplification by checking the scheme of the URI instead of always having a separate "name" -- 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. 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