Golang gossip.MakeStoreKey函數代碼示例

// GossipStore broadcasts the store on the gossip network.
func (s *Store) gossipStore(rangeCount int) error {
	desc := s.getDesc(rangeCount)
	// Unique gossip key per store.
	gossipKey := gossip.MakeStoreKey(desc.StoreID)
	// Gossip store descriptor.
	return s.gossip.AddInfoProto(gossipKey, &desc, 0)
}

// GossipStores queues up a list of stores to gossip and blocks until each one
// is gossiped before returning.
func (sg *StoreGossiper) GossipStores(storeDescs []*roachpb.StoreDescriptor, t *testing.T) {
	storeIDs := make([]roachpb.StoreID, len(storeDescs))
	for i, store := range storeDescs {
		storeIDs[i] = store.StoreID
	}
	sg.GossipWithFunction(storeIDs, func() {
		for i, storeDesc := range storeDescs {
			if err := sg.g.AddInfoProto(gossip.MakeStoreKey(storeIDs[i]), storeDesc, 0); err != nil {
				t.Fatal(err)
			}
		}
	})
}

// GossipWithFunction calls gossipFn and blocks until gossip callbacks have
// fired on each of the stores specified by storeIDs.
func (sg *StoreGossiper) GossipWithFunction(storeIDs []roachpb.StoreID, gossipFn func()) {
	sg.mu.Lock()
	defer sg.mu.Unlock()
	sg.storeKeyMap = make(map[string]struct{})
	for _, storeID := range storeIDs {
		storeKey := gossip.MakeStoreKey(storeID)
		sg.storeKeyMap[storeKey] = struct{}{}
	}

	gossipFn()

	// Wait for gossip callbacks to be invoked on all the stores.
	for len(sg.storeKeyMap) > 0 {
		sg.cond.Wait()
	}
}

// RemoveTarget returns a suitable replica to remove from the provided replica
// set. It attempts to consider which of the provided replicas would be the best
// candidate for removal.
//
// TODO(mrtracy): RemoveTarget eventually needs to accept the attributes from
// the zone config associated with the provided replicas. This will allow it to
// make correct decisions in the case of ranges with heterogeneous replica
// requirements (i.e. multiple data centers).
func (a *allocator) RemoveTarget(existing []proto.Replica) (proto.Replica, error) {
	if len(existing) == 0 {
		return proto.Replica{}, util.Error("must supply at least one replica to allocator.RemoveTarget()")
	}
	a.Lock()
	defer a.Unlock()

	// Retrieve store descriptors for the provided replicas from gossip.
	type replStore struct {
		repl  proto.Replica
		store *proto.StoreDescriptor
	}
	replStores := make([]replStore, len(existing))
	usedStat := stat{}
	for i := range existing {
		desc, err := storeDescFromGossip(gossip.MakeStoreKey(existing[i].StoreID), a.gossip)
		if err != nil {
			return proto.Replica{}, err
		}
		replStores[i] = replStore{
			repl:  existing[i],
			store: desc,
		}
		usedStat.Update(desc.Capacity.FractionUsed())
	}

	// Based on store statistics, determine which replica is the "worst" and
	// thus should be removed.
	var worst replStore
	for i, rs := range replStores {
		if i == 0 {
			worst = rs
			continue
		}

		if usedStat.mean < minFractionUsedThreshold {
			if rs.store.Capacity.RangeCount > worst.store.Capacity.RangeCount {
				worst = rs
			}
			continue
		}
		if rs.store.Capacity.FractionUsed() > worst.store.Capacity.FractionUsed() {
			worst = rs
		}
	}
	return worst.repl, nil
}

func (sg *storeGossiper) gossipStores(stores []*proto.StoreDescriptor, t *testing.T) {
	sg.mu.Lock()
	defer sg.mu.Unlock()

	sg.wg.Add(len(stores))
	for _, s := range stores {
		keyStoreGossip := gossip.MakeStoreKey(s.StoreID)
		// Gossip store descriptor.
		err := sg.g.AddInfoProto(keyStoreGossip, s, 0)
		if err != nil {
			t.Fatal(err)
		}
	}

	// Wait for all gossip callbacks to be invoked.
	sg.wg.Wait()
}

// GossipWithFunction is similar to GossipStores but instead of gossiping the
// store descriptors directly, call the passed in function to do so.
func (sg *StoreGossiper) GossipWithFunction(stores []roachpb.StoreID, gossiper func()) {
	sg.mu.Lock()
	sg.storeKeyMap = make(map[string]struct{})
	sg.wg.Add(len(stores))
	for _, s := range stores {
		storeKey := gossip.MakeStoreKey(s)
		sg.storeKeyMap[storeKey] = struct{}{}
	}

	// Gossip the stores via the passed in function.
	gossiper()

	sg.mu.Unlock()

	// Wait for all gossip callbacks to be invoked.
	sg.wg.Wait()
}

func gossipStores(g *gossip.Gossip, stores []*proto.StoreDescriptor, t *testing.T) {
	var wg sync.WaitGroup
	wg.Add(len(stores))
	g.RegisterCallback(gossip.MakePrefixPattern(gossip.KeyStorePrefix), func(_ string, _ bool, _ interface{}) { wg.Done() })

	for _, s := range stores {
		keyStoreGossip := gossip.MakeStoreKey(s.StoreID)
		// Gossip store descriptor.
		err := g.AddInfo(keyStoreGossip, *s, 0)
		if err != nil {
			t.Fatal(err)
		}
	}

	// Wait for all gossip callbacks to be invoked.
	wg.Wait()
}

// gossipStores queues up a list of stores to gossip and blocks until each one
// is gossiped before returning.
func (sg *storeGossiper) gossipStores(stores []*proto.StoreDescriptor, t *testing.T) {
	sg.mu.Lock()
	sg.storeKeyMap = make(map[string]struct{})
	sg.wg.Add(len(stores))
	for _, s := range stores {
		storeKey := gossip.MakeStoreKey(s.StoreID)
		sg.storeKeyMap[storeKey] = struct{}{}
		// Gossip store descriptor.
		err := sg.g.AddInfoProto(storeKey, s, 0)
		if err != nil {
			t.Fatal(err)
		}
	}
	sg.mu.Unlock()

	// Wait for all gossip callbacks to be invoked.
	sg.wg.Wait()
}

// GossipStores queues up a list of stores to gossip and blocks until each one
// is gossiped before returning.
func (sg *StoreGossiper) GossipStores(stores []*roachpb.StoreDescriptor, t *testing.T) {
	sg.mu.Lock()
	defer sg.mu.Unlock()
	sg.storeKeyMap = make(map[string]struct{})
	for _, s := range stores {
		storeKey := gossip.MakeStoreKey(s.StoreID)
		sg.storeKeyMap[storeKey] = struct{}{}
		// Gossip store descriptor.
		err := sg.g.AddInfoProto(storeKey, s, 0)
		if err != nil {
			t.Fatal(err)
		}
	}

	// Wait for all gossip callbacks to be invoked.
	for len(sg.storeKeyMap) > 0 {
		sg.cond.Wait()
	}
}

func Example_rebalancing() {
	stopper := stop.NewStopper()
	defer stopper.Stop()

	// Model a set of stores in a cluster,
	// randomly adding / removing stores and adding bytes.
	g := gossip.New(nil, nil, stopper)
	// Have to call g.SetNodeID before call g.AddInfo
	g.SetNodeID(roachpb.NodeID(1))
	sp := NewStorePool(
		g,
		hlc.NewClock(hlc.UnixNano),
		nil,
		/* reservationsEnabled */ true,
		TestTimeUntilStoreDeadOff,
		stopper,
	)
	alloc := MakeAllocator(sp, AllocatorOptions{AllowRebalance: true, Deterministic: true})

	var wg sync.WaitGroup
	g.RegisterCallback(gossip.MakePrefixPattern(gossip.KeyStorePrefix), func(_ string, _ roachpb.Value) { wg.Done() })

	const generations = 100
	const nodes = 20

	// Initialize testStores.
	var testStores [nodes]testStore
	for i := 0; i < len(testStores); i++ {
		testStores[i].StoreID = roachpb.StoreID(i)
		testStores[i].Node = roachpb.NodeDescriptor{NodeID: roachpb.NodeID(i)}
		testStores[i].Capacity = roachpb.StoreCapacity{Capacity: 1 << 30, Available: 1 << 30}
	}
	// Initialize the cluster with a single range.
	testStores[0].add(alloc.randGen.Int63n(1 << 20))

	for i := 0; i < generations; i++ {
		// First loop through test stores and add data.
		wg.Add(len(testStores))
		for j := 0; j < len(testStores); j++ {
			// Add a pretend range to the testStore if there's already one.
			if testStores[j].Capacity.RangeCount > 0 {
				testStores[j].add(alloc.randGen.Int63n(1 << 20))
			}
			if err := g.AddInfoProto(gossip.MakeStoreKey(roachpb.StoreID(j)), &testStores[j].StoreDescriptor, 0); err != nil {
				panic(err)
			}
		}
		wg.Wait()

		// Next loop through test stores and maybe rebalance.
		for j := 0; j < len(testStores); j++ {
			ts := &testStores[j]
			if alloc.ShouldRebalance(ts.StoreID) {
				target := alloc.RebalanceTarget(ts.StoreID, roachpb.Attributes{}, []roachpb.ReplicaDescriptor{{NodeID: ts.Node.NodeID, StoreID: ts.StoreID}})
				if target != nil {
					testStores[j].rebalance(&testStores[int(target.StoreID)], alloc.randGen.Int63n(1<<20))
				}
			}
		}

		// Output store capacities as hexidecimal 2-character values.
		if i%(generations/50) == 0 {
			var maxBytes int64
			for j := 0; j < len(testStores); j++ {
				bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
				if bytes > maxBytes {
					maxBytes = bytes
				}
			}
			if maxBytes > 0 {
				for j := 0; j < len(testStores); j++ {
					endStr := " "
					if j == len(testStores)-1 {
						endStr = ""
					}
					bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
					fmt.Printf("%03d%s", (999*bytes)/maxBytes, endStr)
				}
				fmt.Printf("\n")
			}
		}
	}

	var totBytes int64
	var totRanges int32
	for i := 0; i < len(testStores); i++ {
		totBytes += testStores[i].Capacity.Capacity - testStores[i].Capacity.Available
		totRanges += testStores[i].Capacity.RangeCount
	}
	fmt.Printf("Total bytes=%d, ranges=%d\n", totBytes, totRanges)

	// Output:
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 045 140 000 000 000 000 000 105 000 000
	// 999 014 143 000 000 000 000 039 017 000 112 071 000 088 009 000 097 134 000 151
	// 999 196 213 000 000 000 143 098 210 039 262 260 077 139 078 087 237 316 281 267
//.........這裏部分代碼省略.........

func Example_rebalancing() {
	// Model a set of stores in a cluster,
	// randomly adding / removing stores and adding bytes.
	g := gossip.New(nil, 0, nil)
	alloc := newAllocator(g)
	alloc.randGen = rand.New(rand.NewSource(0))
	alloc.deterministic = true

	var wg sync.WaitGroup
	g.RegisterCallback(gossip.MakePrefixPattern(gossip.KeyStorePrefix), func(_ string, _ []byte) { wg.Done() })

	const generations = 100
	const nodes = 20

	// Initialize testStores.
	var testStores [nodes]testStore
	for i := 0; i < len(testStores); i++ {
		testStores[i].StoreID = proto.StoreID(i)
		testStores[i].Node = proto.NodeDescriptor{NodeID: proto.NodeID(i)}
		testStores[i].Capacity = proto.StoreCapacity{Capacity: 1 << 30, Available: 1 << 30}
	}
	// Initialize the cluster with a single range.
	testStores[0].Add(alloc.randGen.Int63n(1 << 20))

	for i := 0; i < generations; i++ {
		// First loop through test stores and add data.
		wg.Add(len(testStores))
		for j := 0; j < len(testStores); j++ {
			// Add a pretend range to the testStore if there's already one.
			if testStores[j].Capacity.RangeCount > 0 {
				testStores[j].Add(alloc.randGen.Int63n(1 << 20))
			}
			key := gossip.MakeStoreKey(proto.StoreID(j))
			if err := g.AddInfoProto(key, &testStores[j].StoreDescriptor, 0); err != nil {
				panic(err)
			}
		}
		wg.Wait()

		// Next loop through test stores and maybe rebalance.
		for j := 0; j < len(testStores); j++ {
			ts := &testStores[j]
			if alloc.ShouldRebalance(&testStores[j].StoreDescriptor) {
				target := alloc.RebalanceTarget(proto.Attributes{}, []proto.Replica{{NodeID: ts.Node.NodeID, StoreID: ts.StoreID}})
				if target != nil {
					testStores[j].Rebalance(&testStores[int(target.StoreID)], alloc.randGen.Int63n(1<<20))
				}
			}
		}

		// Output store capacities as hexidecimal 2-character values.
		if i%(generations/50) == 0 {
			var maxBytes int64
			for j := 0; j < len(testStores); j++ {
				bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
				if bytes > maxBytes {
					maxBytes = bytes
				}
			}
			if maxBytes > 0 {
				for j := 0; j < len(testStores); j++ {
					endStr := " "
					if j == len(testStores)-1 {
						endStr = ""
					}
					bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
					fmt.Printf("%03d%s", (999*bytes)/maxBytes, endStr)
				}
				fmt.Printf("\n")
			}
		}
	}

	var totBytes int64
	var totRanges int32
	for i := 0; i < len(testStores); i++ {
		totBytes += testStores[i].Capacity.Capacity - testStores[i].Capacity.Available
		totRanges += testStores[i].Capacity.RangeCount
	}
	fmt.Printf("Total bytes=%d, ranges=%d\n", totBytes, totRanges)

	// Output:
	// 999 000 000 000 000 000 000 739 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 107 000 000 204 000 000 375 000 000 000 000 000 000 000 000 000 000 536 000
	// 999 310 000 262 872 000 000 208 000 705 000 526 000 000 439 000 000 607 933 000
	// 812 258 000 220 999 673 402 480 000 430 516 374 000 431 318 000 551 714 917 000
	// 582 625 185 334 720 589 647 619 000 300 483 352 279 502 208 665 816 684 999 374
	// 751 617 771 542 738 676 665 525 309 435 612 449 457 616 306 837 993 754 999 445
	// 759 659 828 478 693 622 594 591 349 458 630 538 526 613 462 827 879 787 999 550
	// 861 658 828 559 801 660 681 560 487 529 652 686 642 716 575 999 989 875 989 581
	// 775 647 724 557 779 662 670 494 535 502 681 676 624 695 561 961 999 772 888 592
	// 856 712 753 661 767 658 717 606 529 615 755 699 672 700 576 955 999 755 861 671
	// 882 735 776 685 844 643 740 578 610 688 787 741 661 767 587 999 955 809 803 731
	// 958 716 789 719 861 689 821 608 634 724 800 782 694 799 619 994 999 851 812 818
	// 949 726 788 664 873 633 749 599 680 714 790 728 663 842 628 999 978 816 823 791
	// 923 698 792 712 816 605 774 651 661 728 802 718 670 819 714 999 966 801 829 791
	// 962 779 847 737 900 675 811 691 745 778 835 812 680 894 790 999 989 872 923 799
	// 967 812 826 772 891 685 828 683 761 808 864 820 643 873 783 969 999 873 910 781
	// 923 813 837 739 867 672 792 664 773 772 879 803 610 845 740 957 999 867 912 732
	// 952 803 866 759 881 655 765 668 803 772 929 762 601 844 751 973 999 892 864 731
//.........這裏部分代碼省略.........

func Example_rebalancing() {
	// Model a set of stores in a cluster,
	// randomly adding / removing stores and adding bytes.
	g := gossip.New(nil, 0, nil)
	stopper := stop.NewStopper()
	defer stopper.Stop()
	sp := NewStorePool(g, TestTimeUntilStoreDeadOff, stopper)
	alloc := makeAllocator(sp)
	alloc.randGen = rand.New(rand.NewSource(0))
	alloc.deterministic = true

	var wg sync.WaitGroup
	g.RegisterCallback(gossip.MakePrefixPattern(gossip.KeyStorePrefix), func(_ string, _ []byte) { wg.Done() })

	const generations = 100
	const nodes = 20

	// Initialize testStores.
	var testStores [nodes]testStore
	for i := 0; i < len(testStores); i++ {
		testStores[i].StoreID = proto.StoreID(i)
		testStores[i].Node = proto.NodeDescriptor{NodeID: proto.NodeID(i)}
		testStores[i].Capacity = proto.StoreCapacity{Capacity: 1 << 30, Available: 1 << 30}
	}
	// Initialize the cluster with a single range.
	testStores[0].add(alloc.randGen.Int63n(1 << 20))

	for i := 0; i < generations; i++ {
		// First loop through test stores and add data.
		wg.Add(len(testStores))
		for j := 0; j < len(testStores); j++ {
			// Add a pretend range to the testStore if there's already one.
			if testStores[j].Capacity.RangeCount > 0 {
				testStores[j].add(alloc.randGen.Int63n(1 << 20))
			}
			key := gossip.MakeStoreKey(proto.StoreID(j))
			if err := g.AddInfoProto(key, &testStores[j].StoreDescriptor, 0); err != nil {
				panic(err)
			}
		}
		wg.Wait()

		// Next loop through test stores and maybe rebalance.
		for j := 0; j < len(testStores); j++ {
			ts := &testStores[j]
			if alloc.shouldRebalance(&testStores[j].StoreDescriptor) {
				target := alloc.rebalanceTarget(proto.Attributes{}, []proto.Replica{{NodeID: ts.Node.NodeID, StoreID: ts.StoreID}})
				if target != nil {
					testStores[j].rebalance(&testStores[int(target.StoreID)], alloc.randGen.Int63n(1<<20))
				}
			}
		}

		// Output store capacities as hexidecimal 2-character values.
		if i%(generations/50) == 0 {
			var maxBytes int64
			for j := 0; j < len(testStores); j++ {
				bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
				if bytes > maxBytes {
					maxBytes = bytes
				}
			}
			if maxBytes > 0 {
				for j := 0; j < len(testStores); j++ {
					endStr := " "
					if j == len(testStores)-1 {
						endStr = ""
					}
					bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
					fmt.Printf("%03d%s", (999*bytes)/maxBytes, endStr)
				}
				fmt.Printf("\n")
			}
		}
	}

	var totBytes int64
	var totRanges int32
	for i := 0; i < len(testStores); i++ {
		totBytes += testStores[i].Capacity.Capacity - testStores[i].Capacity.Available
		totRanges += testStores[i].Capacity.RangeCount
	}
	fmt.Printf("Total bytes=%d, ranges=%d\n", totBytes, totRanges)

	// Output:
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 739 000 000
	// 999 107 000 000 000 000 000 000 000 000 177 000 000 000 204 000 000 734 000 000
	// 929 288 000 168 000 057 623 000 114 272 471 000 000 565 385 000 000 999 000 284
	// 683 367 133 087 000 527 381 607 379 380 502 000 188 824 490 295 420 999 000 490
	// 540 443 380 319 000 438 382 534 599 579 602 000 268 859 601 374 450 999 000 532
	// 412 428 539 429 170 332 424 696 505 439 503 691 327 752 427 437 451 999 076 441
	// 496 583 662 586 280 431 499 714 564 578 540 661 431 784 548 516 547 999 329 589
	// 502 563 646 541 430 428 576 693 633 578 537 577 455 803 573 596 528 999 402 639
	// 603 641 764 638 764 521 650 764 713 683 648 652 579 860 610 731 665 999 463 749
	// 615 642 779 688 813 459 650 791 728 702 743 614 526 829 600 767 760 999 497 700
	// 677 677 879 787 867 518 700 852 775 801 793 666 526 820 601 843 767 999 544 772
	// 723 696 866 838 853 589 730 882 800 768 782 695 567 776 656 836 832 999 613 832
	// 830 764 936 879 976 673 824 974 864 825 835 761 703 874 700 909 888 999 635 957
	// 832 766 949 842 995 730 839 965 870 843 790 765 693 931 706 936 936 999 683 948
	// 866 787 990 851 999 780 867 968 892 847 783 787 708 912 768 963 951 954 681 942
//.........這裏部分代碼省略.........

func Example_rebalancing() {
	// Model a set of stores in a cluster,
	// randomly adding / removing stores and adding bytes.
	g := gossip.New(nil, 0, nil)
	stopper := stop.NewStopper()
	defer stopper.Stop()
	sp := NewStorePool(g, TestTimeUntilStoreDeadOff, stopper)
	alloc := MakeAllocator(sp, RebalancingOptions{AllowRebalance: true, Deterministic: true})
	alloc.randGen = rand.New(rand.NewSource(0))

	var wg sync.WaitGroup
	g.RegisterCallback(gossip.MakePrefixPattern(gossip.KeyStorePrefix), func(_ string, _ []byte) { wg.Done() })

	const generations = 100
	const nodes = 20

	// Initialize testStores.
	var testStores [nodes]testStore
	for i := 0; i < len(testStores); i++ {
		testStores[i].StoreID = roachpb.StoreID(i)
		testStores[i].Node = roachpb.NodeDescriptor{NodeID: roachpb.NodeID(i)}
		testStores[i].Capacity = roachpb.StoreCapacity{Capacity: 1 << 30, Available: 1 << 30}
	}
	// Initialize the cluster with a single range.
	testStores[0].add(alloc.randGen.Int63n(1 << 20))

	for i := 0; i < generations; i++ {
		// First loop through test stores and add data.
		wg.Add(len(testStores))
		for j := 0; j < len(testStores); j++ {
			// Add a pretend range to the testStore if there's already one.
			if testStores[j].Capacity.RangeCount > 0 {
				testStores[j].add(alloc.randGen.Int63n(1 << 20))
			}
			key := gossip.MakeStoreKey(roachpb.StoreID(j))
			if err := g.AddInfoProto(key, &testStores[j].StoreDescriptor, 0); err != nil {
				panic(err)
			}
		}
		wg.Wait()

		// Next loop through test stores and maybe rebalance.
		for j := 0; j < len(testStores); j++ {
			ts := &testStores[j]
			if alloc.ShouldRebalance(ts.StoreID) {
				target := alloc.RebalanceTarget(ts.StoreID, roachpb.Attributes{}, []roachpb.ReplicaDescriptor{{NodeID: ts.Node.NodeID, StoreID: ts.StoreID}})
				if target != nil {
					testStores[j].rebalance(&testStores[int(target.StoreID)], alloc.randGen.Int63n(1<<20))
				}
			}
		}

		// Output store capacities as hexidecimal 2-character values.
		if i%(generations/50) == 0 {
			var maxBytes int64
			for j := 0; j < len(testStores); j++ {
				bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
				if bytes > maxBytes {
					maxBytes = bytes
				}
			}
			if maxBytes > 0 {
				for j := 0; j < len(testStores); j++ {
					endStr := " "
					if j == len(testStores)-1 {
						endStr = ""
					}
					bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
					fmt.Printf("%03d%s", (999*bytes)/maxBytes, endStr)
				}
				fmt.Printf("\n")
			}
		}
	}

	var totBytes int64
	var totRanges int32
	for i := 0; i < len(testStores); i++ {
		totBytes += testStores[i].Capacity.Capacity - testStores[i].Capacity.Available
		totRanges += testStores[i].Capacity.RangeCount
	}
	fmt.Printf("Total bytes=%d, ranges=%d\n", totBytes, totRanges)

	// Output:
	// 138 000 000 000 000 000 000 999 000 000 000 000 000 000 000 000 000 000 000 000
	// 922 319 000 000 000 239 000 999 000 000 000 000 000 214 073 000 000 000 190 000
	// 999 505 480 000 634 352 421 644 212 331 396 144 000 242 419 275 000 000 727 028
	// 999 678 908 705 350 558 549 714 651 824 895 694 000 373 610 490 372 106 492 796
	// 932 701 763 999 660 706 571 702 787 945 848 678 062 692 762 413 603 252 513 882
	// 937 656 875 984 734 717 676 685 910 895 847 841 349 754 864 463 722 377 655 999
	// 885 701 805 999 647 744 802 659 778 834 830 725 569 761 922 587 684 458 693 935
	// 813 650 709 931 583 733 843 619 793 881 768 658 565 713 956 598 733 594 656 999
	// 873 727 721 999 544 812 848 666 817 943 831 658 556 769 927 554 799 733 670 869
	// 937 765 827 999 543 875 907 670 929 997 913 768 621 853 922 618 878 832 733 937
	// 902 819 744 988 547 904 922 688 879 999 812 710 554 789 890 591 808 865 658 932
	// 870 873 846 997 596 937 899 765 864 969 855 751 577 824 951 579 858 908 653 999
	// 880 833 856 999 640 918 932 774 920 930 869 739 686 784 853 553 885 941 685 986
	// 874 797 808 999 645 925 928 781 920 956 859 762 678 761 819 627 899 941 725 959
	// 886 801 835 999 638 984 927 825 968 958 860 760 813 716 800 638 908 908 798 945
	// 860 840 836 973 634 999 944 834 977 923 848 769 846 728 836 605 865 915 781 896
//.........這裏部分代碼省略.........

func Example_rebalancing() {
	stopper := stop.NewStopper()
	defer stopper.Stop()

	// Model a set of stores in a cluster,
	// randomly adding / removing stores and adding bytes.
	rpcContext := rpc.NewContext(&base.Context{Insecure: true}, nil, stopper)
	server := rpc.NewServer(rpcContext) // never started
	g := gossip.New(context.Background(), rpcContext, server, nil, stopper, metric.NewRegistry())
	// Have to call g.SetNodeID before call g.AddInfo
	g.SetNodeID(roachpb.NodeID(1))
	sp := NewStorePool(
		g,
		hlc.NewClock(hlc.UnixNano),
		nil,
		/* reservationsEnabled */ true,
		TestTimeUntilStoreDeadOff,
		stopper,
	)
	alloc := MakeAllocator(sp, AllocatorOptions{AllowRebalance: true, Deterministic: true})

	var wg sync.WaitGroup
	g.RegisterCallback(gossip.MakePrefixPattern(gossip.KeyStorePrefix), func(_ string, _ roachpb.Value) { wg.Done() })

	const generations = 100
	const nodes = 20

	// Initialize testStores.
	var testStores [nodes]testStore
	for i := 0; i < len(testStores); i++ {
		testStores[i].StoreID = roachpb.StoreID(i)
		testStores[i].Node = roachpb.NodeDescriptor{NodeID: roachpb.NodeID(i)}
		testStores[i].Capacity = roachpb.StoreCapacity{Capacity: 1 << 30, Available: 1 << 30}
	}
	// Initialize the cluster with a single range.
	testStores[0].add(alloc.randGen.Int63n(1 << 20))

	for i := 0; i < generations; i++ {
		// First loop through test stores and add data.
		wg.Add(len(testStores))
		for j := 0; j < len(testStores); j++ {
			// Add a pretend range to the testStore if there's already one.
			if testStores[j].Capacity.RangeCount > 0 {
				testStores[j].add(alloc.randGen.Int63n(1 << 20))
			}
			if err := g.AddInfoProto(gossip.MakeStoreKey(roachpb.StoreID(j)), &testStores[j].StoreDescriptor, 0); err != nil {
				panic(err)
			}
		}
		wg.Wait()

		// Next loop through test stores and maybe rebalance.
		for j := 0; j < len(testStores); j++ {
			ts := &testStores[j]
			target := alloc.RebalanceTarget(
				roachpb.Attributes{},
				[]roachpb.ReplicaDescriptor{{NodeID: ts.Node.NodeID, StoreID: ts.StoreID}},
				-1)
			if target != nil {
				testStores[j].rebalance(&testStores[int(target.StoreID)], alloc.randGen.Int63n(1<<20))
			}
		}

		// Output store capacities as hexadecimal 2-character values.
		if i%(generations/50) == 0 {
			var maxBytes int64
			for j := 0; j < len(testStores); j++ {
				bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
				if bytes > maxBytes {
					maxBytes = bytes
				}
			}
			if maxBytes > 0 {
				for j := 0; j < len(testStores); j++ {
					endStr := " "
					if j == len(testStores)-1 {
						endStr = ""
					}
					bytes := testStores[j].Capacity.Capacity - testStores[j].Capacity.Available
					fmt.Printf("%03d%s", (999*bytes)/maxBytes, endStr)
				}
				fmt.Printf("\n")
			}
		}
	}

	var totBytes int64
	var totRanges int32
	for i := 0; i < len(testStores); i++ {
		totBytes += testStores[i].Capacity.Capacity - testStores[i].Capacity.Available
		totRanges += testStores[i].Capacity.RangeCount
	}
	fmt.Printf("Total bytes=%d, ranges=%d\n", totBytes, totRanges)

	// Output:
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
	// 999 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000
//.........這裏部分代碼省略.........