12312390362

Committed 13 Dec 2024 08:44AM UTC coverage: 57.458% (+8.5%) from 48.92%

Build # 12312390362

Build Type

Pull #9343

github

Committed by

ellemouton

Commit Message

fn: rework the ContextGuard and add tests

In this commit, the ContextGuard struct is re-worked such that the
context that its new main WithCtx method provides is cancelled in sync
with a parent context being cancelled or with it's quit channel being
cancelled. Tests are added to assert the behaviour. In order for the
close of the quit channel to be consistent with the cancelling of the
derived context, the quit channel _must_ be contained internal to the
ContextGuard so that callers are only able to close the channel via the
exposed Quit method which will then take care to first cancel any
derived context that depend on the quit channel before returning.

Pull Request Pull Request #9343: fn: expand the ContextGuard and add tests

Run Details

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76.19

/chainntnfs/best_block_view.go

package chainntnfs

import (
        "errors"
        "fmt"
        "sync"
        "sync/atomic"

        "github.com/btcsuite/btcd/wire"
)

// BestBlockView is an interface that allows the querying of the most
// up-to-date blockchain state with low overhead. Valid implementations of this
// interface must track the latest chain state.
type BestBlockView interface {
        // BestHeight gets the most recent block height known to the view.
        BestHeight() (uint32, error)

        // BestBlockHeader gets the most recent block header known to the view.
        BestBlockHeader() (*wire.BlockHeader, error)
}

// BestBlockTracker is a tiny subsystem that tracks the blockchain tip
// and saves the most recent tip information in memory for querying. It is a
// valid implementation of BestBlockView and additionally includes
// methods for starting and stopping the system.
type BestBlockTracker struct {
        notifier        ChainNotifier
        blockNtfnStream *BlockEpochEvent
        current         atomic.Pointer[BlockEpoch]
        mu              sync.Mutex
        quit            chan struct{}
        wg              sync.WaitGroup
}

// This is a compile time check to ensure that BestBlockTracker implements
// BestBlockView.
var _ BestBlockView = (*BestBlockTracker)(nil)

// NewBestBlockTracker creates a new BestBlockTracker that isn't running yet.
// It will not provide up to date information unless it has been started. The
// ChainNotifier parameter must also be started prior to starting the
// BestBlockTracker.
func NewBestBlockTracker(chainNotifier ChainNotifier) *BestBlockTracker {
        return &BestBlockTracker{
                notifier:        chainNotifier,
                blockNtfnStream: nil,
                quit:            make(chan struct{}),
        }
}

// BestHeight gets the most recent block height known to the
// BestBlockTracker.
func (t *BestBlockTracker) BestHeight() (uint32, error) {
        epoch := t.current.Load()
        if epoch == nil {
                return 0, errors.New("best block height not yet known")
        }

        return uint32(epoch.Height), nil
}

// BestBlockHeader gets the most recent block header known to the
// BestBlockTracker.
func (t *BestBlockTracker) BestBlockHeader() (*wire.BlockHeader, error) {
        epoch := t.current.Load()
        if epoch == nil {
                return nil, errors.New("best block header not yet known")
        }

        return epoch.BlockHeader, nil
}

// updateLoop is a helper that subscribes to the underlying BlockEpochEvent
// stream and updates the internal values to match the new BlockEpochs that
// are discovered.
//
// MUST be run as a goroutine.
func (t *BestBlockTracker) updateLoop() {
        defer t.wg.Done()
        for {
                select {
                case epoch, ok := <-t.blockNtfnStream.Epochs:
                        if !ok {
                                Log.Error("dead epoch stream in " +
                                        "BestBlockTracker")

                                return
                        }
                        t.current.Store(epoch)
                case <-t.quit:
                        t.current.Store(nil)
                        return
                }
        }
}

// Start starts the BestBlockTracker. It is an error to start it if it
// is already started.
func (t *BestBlockTracker) Start() error {
        t.mu.Lock()
        defer t.mu.Unlock()

        if t.blockNtfnStream != nil {
                return fmt.Errorf("BestBlockTracker is already started")
        }

        var err error
        t.blockNtfnStream, err = t.notifier.RegisterBlockEpochNtfn(nil)
        if err != nil {
                return err
        }

        t.wg.Add(1)
        go t.updateLoop()

        return nil
}

// Stop stops the BestBlockTracker. It is an error to stop it if it has
// not been started or if it has already been stopped.
func (t *BestBlockTracker) Stop() error {
        t.mu.Lock()
        defer t.mu.Unlock()

        if t.blockNtfnStream == nil {
                return fmt.Errorf("BestBlockTracker is not running")
        }
        close(t.quit)
        t.wg.Wait()
        t.blockNtfnStream.Cancel()
        t.blockNtfnStream = nil

        return nil
}

1	package chainntnfs
2
3	import (
4	"errors"
5	"fmt"
6	"sync"
7	"sync/atomic"
8
9	"github.com/btcsuite/btcd/wire"
10	)
11
12	// BestBlockView is an interface that allows the querying of the most
13	// up-to-date blockchain state with low overhead. Valid implementations of this
14	// interface must track the latest chain state.
15	type BestBlockView interface {
16	// BestHeight gets the most recent block height known to the view.
17	BestHeight() (uint32, error)
18
19	// BestBlockHeader gets the most recent block header known to the view.
20	BestBlockHeader() (*wire.BlockHeader, error)
21	}
22
23	// BestBlockTracker is a tiny subsystem that tracks the blockchain tip
24	// and saves the most recent tip information in memory for querying. It is a
25	// valid implementation of BestBlockView and additionally includes
26	// methods for starting and stopping the system.
27	type BestBlockTracker struct {
28	notifier ChainNotifier
29	blockNtfnStream *BlockEpochEvent
30	current atomic.Pointer[BlockEpoch]
31	mu sync.Mutex
32	quit chan struct{}
33	wg sync.WaitGroup
34	}
35
36	// This is a compile time check to ensure that BestBlockTracker implements
37	// BestBlockView.
38	var _ BestBlockView = (*BestBlockTracker)(nil)
39
40	// NewBestBlockTracker creates a new BestBlockTracker that isn't running yet.
41	// It will not provide up to date information unless it has been started. The
42	// ChainNotifier parameter must also be started prior to starting the
43	// BestBlockTracker.
44	func NewBestBlockTracker(chainNotifier ChainNotifier) *BestBlockTracker {	1✔
45	return &BestBlockTracker{	1✔
46	notifier: chainNotifier,	1✔
47	blockNtfnStream: nil,	1✔
48	quit: make(chan struct{}),	1✔
49	}	1✔
50	}	1✔
51
52	// BestHeight gets the most recent block height known to the
53	// BestBlockTracker.
54	func (t *BestBlockTracker) BestHeight() (uint32, error) {	250✔
55	epoch := t.current.Load()	250✔
56	if epoch == nil {	250✔
57	return 0, errors.New("best block height not yet known")	×
58	}	×
59
60	return uint32(epoch.Height), nil	250✔
61	}
62
63	// BestBlockHeader gets the most recent block header known to the
64	// BestBlockTracker.
65	func (t BestBlockTracker) BestBlockHeader() (wire.BlockHeader, error) {	150✔
66	epoch := t.current.Load()	150✔
67	if epoch == nil {	150✔
68	return nil, errors.New("best block header not yet known")	×
69	}	×
70
71	return epoch.BlockHeader, nil	150✔
72	}
73
74	// updateLoop is a helper that subscribes to the underlying BlockEpochEvent
75	// stream and updates the internal values to match the new BlockEpochs that
76	// are discovered.
77	//
78	// MUST be run as a goroutine.
79	func (t *BestBlockTracker) updateLoop() {	1✔
80	defer t.wg.Done()	1✔
81	for {	102✔
82	select {	101✔
83	case epoch, ok := <-t.blockNtfnStream.Epochs:	100✔
84	if !ok {	100✔
85	Log.Error("dead epoch stream in " +	×
86	"BestBlockTracker")	×
87		×
88	return	×
89	}	×
90	t.current.Store(epoch)	100✔
91	case <-t.quit:	1✔
92	t.current.Store(nil)	1✔
93	return	1✔
94	}
95	}
96	}
97
98	// Start starts the BestBlockTracker. It is an error to start it if it
99	// is already started.
100	func (t *BestBlockTracker) Start() error {	1✔
101	t.mu.Lock()	1✔
102	defer t.mu.Unlock()	1✔
103		1✔
104	if t.blockNtfnStream != nil {	1✔
105	return fmt.Errorf("BestBlockTracker is already started")	×
106	}	×
107
108	var err error	1✔
109	t.blockNtfnStream, err = t.notifier.RegisterBlockEpochNtfn(nil)	1✔
110	if err != nil {	1✔
111	return err	×
112	}	×
113
114	t.wg.Add(1)	1✔
115	go t.updateLoop()	1✔
116		1✔
117	return nil	1✔
118	}
119
120	// Stop stops the BestBlockTracker. It is an error to stop it if it has
121	// not been started or if it has already been stopped.
122	func (t *BestBlockTracker) Stop() error {	1✔
123	t.mu.Lock()	1✔
124	defer t.mu.Unlock()	1✔
125		1✔
126	if t.blockNtfnStream == nil {	1✔
127	return fmt.Errorf("BestBlockTracker is not running")	×
128	}	×
129	close(t.quit)	1✔
130	t.wg.Wait()	1✔
131	t.blockNtfnStream.Cancel()	1✔
132	t.blockNtfnStream = nil	1✔
133		1✔
134	return nil	1✔
135	}

lightningnetwork / lnd / 12312390362

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