indigophox commented on code in PR #40284: URL: https://github.com/apache/arrow/pull/40284#discussion_r1509608618
########## go/arrow/flight/session/session.go: ########## @@ -0,0 +1,233 @@ +// 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 session provides server middleware and reference implementations for Flight session management. +// +// The existing middleware implementation uses cookies, so any client would need middleware/support for storing and sending those cookies. +// Both stateful and stateless session cookie implementations are provided. +// The default stateful implementation persists sessions in-memory, but a custom SessionStore may be provided for more durable persistence. +// Stateless session cookies may be used with no additional infrastructure, but they are not encrypted and should not contain sensitive information. +package session + +import ( + "context" + "errors" + "fmt" + "net/http" + "sync" + + "github.com/apache/arrow/go/v16/arrow/flight" + "google.golang.org/grpc" + "google.golang.org/grpc/metadata" + "google.golang.org/protobuf/proto" +) + +var ErrNoSession error = errors.New("flight: server session not present") + +type sessionMiddlewareKey struct{} + +// Return a copy of the provided context containing the provided ServerSession +func NewSessionContext(ctx context.Context, session ServerSession) context.Context { + return context.WithValue(ctx, sessionMiddlewareKey{}, session) +} + +// Retrieve the ServerSession from the provided context if it exists. +// An error indicates that the session was not found in the context. +func GetSessionFromContext(ctx context.Context) (ServerSession, error) { + session, ok := ctx.Value(sessionMiddlewareKey{}).(ServerSession) + if !ok { + return nil, ErrNoSession + } + return session, nil +} + +// Container for named SessionOptionValues +type ServerSession interface { + // An identifier for the session that the server can use to reconstruct + // the session state on future requests. It is the responsibility of + // each implementation to define the token's semantics. + Token() string + // Get session option value by name, or nil if it does not exist + GetSessionOption(name string) *flight.SessionOptionValue + // Get a copy of the session options + GetSessionOptions() map[string]*flight.SessionOptionValue + // Set session option by name to given value + SetSessionOption(name string, value *flight.SessionOptionValue) + // Idempotently remove name from this session + EraseSessionOption(name string) + // Close the session + Close() error + // Report whether the session has been closed + Closed() bool +} + +// Handles session lifecycle management +type ServerSessionManager interface { + // Create a new, empty ServerSession + CreateSession(ctx context.Context) (ServerSession, error) + // Get the current ServerSession, if one exists + GetSession(ctx context.Context) (ServerSession, error) + // Cleanup any resources associated with the current ServerSession + CloseSession(session ServerSession) error +} + +// Implementation of common session behavior. Intended to be extended +// by specific session implementations. +type serverSession struct { + closed bool + + options map[string]*flight.SessionOptionValue + mu sync.RWMutex +} + +func (session *serverSession) GetSessionOption(name string) *flight.SessionOptionValue { + session.mu.RLock() + defer session.mu.RUnlock() + value, found := session.options[name] + if !found { + return nil + } + + return value +} + +func (session *serverSession) GetSessionOptions() map[string]*flight.SessionOptionValue { + options := make(map[string]*flight.SessionOptionValue, len(session.options)) + + session.mu.RLock() + defer session.mu.RUnlock() + for k, v := range session.options { + options[k] = proto.Clone(v).(*flight.SessionOptionValue) + } + + return options +} + +func (session *serverSession) SetSessionOption(name string, value *flight.SessionOptionValue) { + if value.GetOptionValue() == nil { + session.EraseSessionOption(name) + return + } + + session.mu.Lock() + defer session.mu.Unlock() + session.options[name] = value +} + +func (session *serverSession) EraseSessionOption(name string) { + session.mu.Lock() + defer session.mu.Unlock() + delete(session.options, name) +} + +func (session *serverSession) Close() error { + session.options = nil + session.closed = true + return nil +} + +func (session *serverSession) Closed() bool { + return session.closed +} + +// Create new instance of CustomServerMiddleware implementing server session persistence. +// +// The provided manager can be used to customize session implementation/behavior. +// If no manager is provided, a stateful in-memory, goroutine-safe implementation is used. +func NewServerSessionMiddleware(manager ServerSessionManager) *serverSessionMiddleware { + // Default manager Review Comment: The shipped middleware classes for C++ and Java both provide their own option value store, presently without the option to inject a separate k:v store implementation—although that could be accomplished via a subclass of the provided middleware factory. -- This is an automated message from the Apache Git Service. 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