feat: Sequential and Parallel Routers

compconfig.go

@@ -0,0 +1,27 @@
+package routinghelpers
+
+import (
+	"context"
+	"time"
+
+	"github.com/libp2p/go-libp2p/core/routing"
+	"github.com/multiformats/go-multihash"
+)
+
+type ParallelRouter struct {
+	Timeout      time.Duration
+	IgnoreError  bool
+	Router       routing.Routing
+	ExecuteAfter time.Duration
+}
+
+type SequentialRouter struct {
+	Timeout     time.Duration
+	IgnoreError bool
+	Router      routing.Routing
+}
+
+type ProvideManyRouter interface {
+	ProvideMany(ctx context.Context, keys []multihash.Multihash) error
+	Ready() bool
+}

compparallel.go

@@ -0,0 +1,323 @@
+package routinghelpers
+
+import (
+	"context"
+	"errors"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/hashicorp/go-multierror"
+	"github.com/ipfs/go-cid"
+	"github.com/libp2p/go-libp2p/core/peer"
+	"github.com/libp2p/go-libp2p/core/routing"
+	"github.com/multiformats/go-multihash"
+)
+
+var _ routing.Routing = &composableParallel{}
+var _ ProvideManyRouter = &composableParallel{}
+
+type composableParallel struct {
+	routers []*ParallelRouter
+}
+
+// NewComposableParallel creates a Router that will execute methods from provided Routers in parallel.
+// On all methods, If IgnoreError flag is set, that Router will not stop the entire execution.
+// On all methods, If ExecuteAfter is set, that Router will be executed after the timer.
+// Router specific timeout will start counting AFTER the ExecuteAfter timer.
+func NewComposableParallel(routers []*ParallelRouter) *composableParallel {
+	return &composableParallel{
+		routers: routers,
+	}
+}
+
+// Provide will call all Routers in parallel.
+func (r *composableParallel) Provide(ctx context.Context, cid cid.Cid, provide bool) error {
+	return executeParallel(ctx, r.routers,
+		func(ctx context.Context, r routing.Routing) error {
+			return r.Provide(ctx, cid, provide)
+		},
+	)
+}
+
+// ProvideMany will call all supported Routers in parallel.
+func (r *composableParallel) ProvideMany(ctx context.Context, keys []multihash.Multihash) error {
+	return executeParallel(ctx, r.routers,
+		func(ctx context.Context, r routing.Routing) error {
+			pm, ok := r.(ProvideManyRouter)
+			if !ok {
+				return nil
+			}
+			return pm.ProvideMany(ctx, keys)
+		},
+	)
+}
+
+// Ready will call all supported ProvideMany Routers SEQUENTIALLY.
+// If some of them are not ready, this method will return false.
+func (r *composableParallel) Ready() bool {
+	for _, ro := range r.routers {
+		pm, ok := ro.Router.(ProvideManyRouter)
+		if !ok {
+			continue
+		}
+
+		if !pm.Ready() {
+			return false
+		}
+	}
+
+	return true
+}
+
+// FindProvidersAsync will execute all Routers in parallel, iterating results from them in unspecified order.
+// If count is set, only that amount of elements will be returned without any specification about from what router is obtained.
+// To gather providers from a set of Routers first, you can use the ExecuteAfter timer to delay some Router execution.
+func (r *composableParallel) FindProvidersAsync(ctx context.Context, cid cid.Cid, count int) <-chan peer.AddrInfo {
+	var totalCount int64
+	ch, _ := getChannelOrErrorParallel(
+		ctx,
+		r.routers,
+		func(ctx context.Context, r routing.Routing) (<-chan peer.AddrInfo, error) {
+			return r.FindProvidersAsync(ctx, cid, count), nil
+		},
+		func() bool {
+			return atomic.AddInt64(&totalCount, 1) > int64(count) && count != 0
+		},
+	)
+
+	return ch
+}
+
+// FindPeer will execute all Routers in parallel, getting the first AddrInfo found and cancelling all other Router calls.
+func (r *composableParallel) FindPeer(ctx context.Context, id peer.ID) (peer.AddrInfo, error) {
+	return getValueOrErrorParallel(ctx, r.routers,
+		func(ctx context.Context, r routing.Routing) (peer.AddrInfo, bool, error) {
+			addr, err := r.FindPeer(ctx, id)
+			return addr, addr.ID == "", err
+		},
+	)
+}
+
+// PutValue will execute all Routers in parallel. If a Router fails and IgnoreError flag is not set, the whole execution will fail.
+// Some Puts before the failure might be successful, even if we return an error.
+func (r *composableParallel) PutValue(ctx context.Context, key string, val []byte, opts ...routing.Option) error {
+	return executeParallel(ctx, r.routers,
+		func(ctx context.Context, r routing.Routing) error {
+			return r.PutValue(ctx, key, val, opts...)
+		},
+	)
+}
+
+// GetValue will execute all Routers in parallel. The first value found will be returned, cancelling all other executions.
+func (r *composableParallel) GetValue(ctx context.Context, key string, opts ...routing.Option) ([]byte, error) {
+	return getValueOrErrorParallel(ctx, r.routers,
+		func(ctx context.Context, r routing.Routing) ([]byte, bool, error) {
+			val, err := r.GetValue(ctx, key, opts...)
+			return val, len(val) == 0, err
+		})
+}
+
+func (r *composableParallel) SearchValue(ctx context.Context, key string, opts ...routing.Option) (<-chan []byte, error) {
+	return getChannelOrErrorParallel(
+		ctx,
+		r.routers,
+		func(ctx context.Context, r routing.Routing) (<-chan []byte, error) {
+			return r.SearchValue(ctx, key, opts...)
+		},
+		func() bool { return false },
+	)
+}
+
+func (r *composableParallel) Bootstrap(ctx context.Context) error {
+	return executeParallel(ctx, r.routers,
+		func(ctx context.Context, r routing.Routing) error {
+			return r.Bootstrap(ctx)
+		})
+}
+
+func getValueOrErrorParallel[T any](
+	ctx context.Context,
+	routers []*ParallelRouter,
+	f func(context.Context, routing.Routing) (T, bool, error),
+) (value T, err error) {
+	outCh := make(chan T)
+	errCh := make(chan error)
+
+	// global cancel context to stop early other router's execution.
+	ctx, cancelAll := context.WithCancel(ctx)
+	defer cancelAll()
+	var wg sync.WaitGroup
+	for _, r := range routers {
+		wg.Add(1)
+		go func(r *ParallelRouter) {
+			defer wg.Done()
+			tim := time.NewTimer(r.ExecuteAfter)
+			defer tim.Stop()
+			select {
+			case <-ctx.Done():
+			case <-tim.C:
+				ctx, cancel := context.WithTimeout(ctx, r.Timeout)
+				defer cancel()
+				value, empty, err := f(ctx, r.Router)
+				if err != nil &&
+					!errors.Is(err, routing.ErrNotFound) &&
+					!r.IgnoreError {
+					select {
+					case <-ctx.Done():
+					case errCh <- err:
+					}
+					return
+				}
+				if empty {
+					return
+				}
+				select {
+				case <-ctx.Done():
+					return
+				case outCh <- value:
+				}
+			}
+		}(r)
+	}
+
+	// goroutine closing everything when finishing execution
+	go func() {
+		wg.Wait()
+		close(outCh)
+		close(errCh)
+	}()
+
+	select {
+	case out, ok := <-outCh:
+		if !ok {
+			return value, routing.ErrNotFound
+		}
+		return out, nil
+	case err, ok := <-errCh:
+		if !ok {
+			return value, routing.ErrNotFound
+		}
+		return value, err
+	case <-ctx.Done():
+		return value, ctx.Err()
+	}
+}
+
+func executeParallel(
+	ctx context.Context,
+	routers []*ParallelRouter,
+	f func(context.Context, routing.Routing,
+	) error) error {
+	var wg sync.WaitGroup
+	errCh := make(chan error)
+	for _, r := range routers {
+		wg.Add(1)
+		go func(r *ParallelRouter) {
+			defer wg.Done()
+			tim := time.NewTimer(r.ExecuteAfter)
+			defer tim.Stop()
+			select {
+			case <-ctx.Done():
+				if !r.IgnoreError {
+					errCh <- ctx.Err()
+				}
+			case <-tim.C:
+				ctx, cancel := context.WithTimeout(ctx, r.Timeout)
+				defer cancel()
+				err := f(ctx, r.Router)
+				if err != nil &&
+					!r.IgnoreError {
+					errCh <- err
+				}
+			}
+		}(r)
+	}
+
+	go func() {
+		wg.Wait()
+		close(errCh)
+	}()
+
+	var errOut error
+	for err := range errCh {
+		errOut = multierror.Append(errOut, err)
+	}
+
+	return errOut
+}
+
+func getChannelOrErrorParallel[T any](
+	ctx context.Context,
+	routers []*ParallelRouter,
+	f func(context.Context, routing.Routing) (<-chan T, error),
+	shouldStop func() bool,
+) (chan T, error) {
+	outCh := make(chan T)
+	errCh := make(chan error)
+	var wg sync.WaitGroup
+	ctx, cancelAll := context.WithCancel(ctx)
+	for _, r := range routers {
+		wg.Add(1)
+		go func(r *ParallelRouter) {
+			defer wg.Done()
+			tim := time.NewTimer(r.ExecuteAfter)
+			defer tim.Stop()
+			select {
+			case <-ctx.Done():
+				return
+			case <-tim.C:
+				ctx, cancel := context.WithTimeout(ctx, r.Timeout)
+				defer cancel()
+				valueChan, err := f(ctx, r.Router)
+				if err != nil && !r.IgnoreError {
+					select {
+					case <-ctx.Done():
+					case errCh <- err:
+					}
+					return
+				}
+				for {
+					select {
+					case <-ctx.Done():
+						return
+					case val, ok := <-valueChan:
+						if !ok {
+							return
+						}
+
+						if shouldStop() {
+							return
+						}
+
+						select {
+						case <-ctx.Done():
+							return
+						case outCh <- val:
+						}
+					}
+				}
+			}
+		}(r)
+	}
+
+	// goroutine closing everything when finishing execution
+	go func() {
+		wg.Wait()
+		close(outCh)
+		close(errCh)
+		cancelAll()
+	}()
+
+	select {
+	case err, ok := <-errCh:
+		if !ok {
+			return nil, routing.ErrNotFound
+		}
+		return nil, err
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+		return outCh, nil
+	}
+}