swarm: network rewrite merge

swarm/network/priorityqueue/priorityqueue.go

@@ -0,0 +1,111 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// package priority_queue implement a channel based priority queue
+// over arbitrary types. It provides an
+// an autopop loop applying a function to the items always respecting
+// their priority. The structure is only quasi consistent ie., if a lower
+// priority item is autopopped, it is guaranteed that there was a point
+// when no higher priority item was present, ie. it is not guaranteed
+// that there was any point where the lower priority item was present
+// but the higher was not
+
+package priorityqueue
+
+import (
+	"context"
+	"errors"
+)
+
+var (
+	errContention  = errors.New("queue contention")
+	errBadPriority = errors.New("bad priority")
+
+	wakey = struct{}{}
+)
+
+// PriorityQueue is the basic structure
+type PriorityQueue struct {
+	queues []chan interface{}
+	wakeup chan struct{}
+}
+
+// New is the constructor for PriorityQueue
+func New(n int, l int) *PriorityQueue {
+	var queues = make([]chan interface{}, n)
+	for i := range queues {
+		queues[i] = make(chan interface{}, l)
+	}
+	return &PriorityQueue{
+		queues: queues,
+		wakeup: make(chan struct{}, 1),
+	}
+}
+
+// Run is a forever loop popping items from the queues
+func (pq *PriorityQueue) Run(ctx context.Context, f func(interface{})) {
+	top := len(pq.queues) - 1
+	p := top
+READ:
+	for {
+		q := pq.queues[p]
+		select {
+		case <-ctx.Done():
+			return
+		case x := <-q:
+			f(x)
+			p = top
+		default:
+			if p > 0 {
+				p--
+				continue READ
+			}
+			p = top
+			select {
+			case <-ctx.Done():
+				return
+			case <-pq.wakeup:
+			}
+		}
+	}
+}
+
+// Push pushes an item to the appropriate queue specified in the priority argument
+// if context is given it waits until either the item is pushed or the Context aborts
+// otherwise returns errContention if the queue is full
+func (pq *PriorityQueue) Push(ctx context.Context, x interface{}, p int) error {
+	if p < 0 || p >= len(pq.queues) {
+		return errBadPriority
+	}
+	if ctx == nil {
+		select {
+		case pq.queues[p] <- x:
+		default:
+			return errContention
+		}
+	} else {
+		select {
+		case pq.queues[p] <- x:
+		case <-ctx.Done():
+			return ctx.Err()
+		}
+	}
+	select {
+	case pq.wakeup <- wakey:
+	default:
+	}
+	return nil
+}

swarm/network/priorityqueue/priorityqueue_test.go

@@ -0,0 +1,97 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+package priorityqueue
+
+import (
+	"context"
+	"sync"
+	"testing"
+)
+
+func TestPriorityQueue(t *testing.T) {
+	var results []string
+	wg := sync.WaitGroup{}
+	pq := New(3, 2)
+	wg.Add(1)
+	go pq.Run(context.Background(), func(v interface{}) {
+		results = append(results, v.(string))
+		wg.Done()
+	})
+	pq.Push(context.Background(), "2.0", 2)
+	wg.Wait()
+	if results[0] != "2.0" {
+		t.Errorf("expected first result %q, got %q", "2.0", results[0])
+	}
+
+Loop:
+	for i, tc := range []struct {
+		priorities []int
+		values     []string
+		results    []string
+		errors     []error
+	}{
+		{
+			priorities: []int{0},
+			values:     []string{""},
+			results:    []string{""},
+		},
+		{
+			priorities: []int{0, 1},
+			values:     []string{"0.0", "1.0"},
+			results:    []string{"1.0", "0.0"},
+		},
+		{
+			priorities: []int{1, 0},
+			values:     []string{"1.0", "0.0"},
+			results:    []string{"1.0", "0.0"},
+		},
+		{
+			priorities: []int{0, 1, 1},
+			values:     []string{"0.0", "1.0", "1.1"},
+			results:    []string{"1.0", "1.1", "0.0"},
+		},
+		{
+			priorities: []int{0, 0, 0},
+			values:     []string{"0.0", "0.0", "0.1"},
+			errors:     []error{nil, nil, errContention},
+		},
+	} {
+		var results []string
+		wg := sync.WaitGroup{}
+		pq := New(3, 2)
+		wg.Add(len(tc.values))
+		for j, value := range tc.values {
+			err := pq.Push(nil, value, tc.priorities[j])
+			if tc.errors != nil && err != tc.errors[j] {
+				t.Errorf("expected push error %v, got %v", tc.errors[j], err)
+				continue Loop
+			}
+			if err != nil {
+				continue Loop
+			}
+		}
+		go pq.Run(context.Background(), func(v interface{}) {
+			results = append(results, v.(string))
+			wg.Done()
+		})
+		wg.Wait()
+		for k, result := range tc.results {
+			if results[k] != result {
+				t.Errorf("test case %v: expected %v element %q, got %q", i, k, result, results[k])
+			}
+		}
+	}
+}