context.go

package log

import (
	"context"

	"github.com/google/uuid"
)

type correlationIDType int

const (
	requestIDKey correlationIDType = iota
	sessionIDKey

	// Request and Session fields need to be separate so that each can have extra fields associated
	// with it and they don't overwrite each other.
	requestFieldsKey
	sessionFieldsKey

	// PeerIDKey is used to store the peer ID in the p2p stack.
	PeerIDKey
)

// WithRequestID returns a context which knows its request ID.
// A request ID tracks the lifecycle of a single request across all execution contexts, including
// multiple goroutines, task queues, workers, etc. The canonical example is an incoming message
// received over the network. Rule of thumb: requests "traverse the heap" and may be passed from one
// session to another via channels.
// This requires a requestId string, and optionally, other LoggableFields that are added to
// context and printed in contextual logs.
func WithRequestID(ctx context.Context, requestID string, fields ...LoggableField) context.Context {
	// Warn if overwriting. This is expected. It happens every time an inbound request triggers a new
	// outbound request, e.g., a newly-received block causes us to request the blocks and ATXs it refers to.
	// But it's important that we log the old and new reqIDs here so that the thread can be followed.
	if curRequestID, ok := ExtractRequestID(ctx); ok && curRequestID != requestID {
		GetLogger().WithContext(ctx).With().Info("overwriting requestID in context",
			String("old_request_id", curRequestID),
			String("new_request_id", requestID))
	}
	ctx = context.WithValue(ctx, requestIDKey, requestID)
	if len(fields) > 0 {
		ctx = context.WithValue(ctx, requestFieldsKey, fields)
	}
	return ctx
}

// WithNewRequestID does the same thing as WithRequestID but generates a new, random requestId.
// It can be used when there isn't a single, clear, unique id associated with a request (e.g.,
// a block or tx hash).
func WithNewRequestID(ctx context.Context, fields ...LoggableField) context.Context {
	return WithRequestID(ctx, uuid.New().String(), fields...)
}

// ExtractSessionID extracts the session id from a context object.
func ExtractSessionID(ctx context.Context) (string, bool) {
	if ctxSessionID, ok := ctx.Value(sessionIDKey).(string); ok {
		return ctxSessionID, true
	}
	return "", false
}

// ExtractRequestID extracts the request id from a context object.
func ExtractRequestID(ctx context.Context) (string, bool) {
	if ctxRequestID, ok := ctx.Value(requestIDKey).(string); ok {
		return ctxRequestID, true
	}
	return "", false
}

// ExtractSessionFields extracts additional loggable fields associated with the session from a context object.
func ExtractSessionFields(ctx context.Context) (fields []LoggableField) {
	if sessionFields, ok := ctx.Value(sessionFieldsKey).([]LoggableField); ok {
		fields = sessionFields
	}
	return
}

// ExtractRequestFields extracts additional loggable fields associated with the request from a context object.
func ExtractRequestFields(ctx context.Context) (fields []LoggableField) {
	if requestFields, ok := ctx.Value(requestFieldsKey).([]LoggableField); ok {
		fields = requestFields
	}
	return
}

// WithSessionID returns a context which knows its session ID
// A session ID tracks a single thread of execution. This may include multiple goroutines running
// concurrently, but it does not include asynchronous task execution such as task queues handled
// in separate threads. The canonical example is a single protocol routine, down to the point where
// an incoming request is either handled, or else handed off to another routine via a channel. Rule
// of thumb: sessions live entirely on the stack, and never on the heap (and should not be passed over
// channels).
// This requires a sessionId string, and optionally, other LoggableFields that are added to
// context and printed in contextual logs.
func WithSessionID(ctx context.Context, sessionID string, fields ...LoggableField) context.Context {
	ctx = context.WithValue(ctx, sessionIDKey, sessionID)
	if len(fields) > 0 {
		ctx = context.WithValue(ctx, sessionFieldsKey, fields)
	}
	return ctx
}

// WithNewSessionID does the same thing as WithSessionID but generates a new, random sessionId.
// It can be used when there isn't a single, clear, unique id associated with a session.
func WithNewSessionID(ctx context.Context, fields ...LoggableField) context.Context {
	return WithSessionID(ctx, uuid.New().String(), fields...)
}