6757e14998
This refactor removes a redundancy where we had etcd configuration under kvdb and kvdb/etcd packages.
278 lines
7.5 KiB
Go
278 lines
7.5 KiB
Go
// +build kvdb_etcd
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package etcd
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import (
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"context"
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"fmt"
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"io"
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"runtime"
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"sync"
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"time"
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"github.com/btcsuite/btcwallet/walletdb"
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"github.com/coreos/etcd/clientv3"
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"github.com/coreos/etcd/clientv3/namespace"
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"github.com/coreos/etcd/pkg/transport"
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)
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const (
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// etcdConnectionTimeout is the timeout until successful connection to
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// the etcd instance.
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etcdConnectionTimeout = 10 * time.Second
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// etcdLongTimeout is a timeout for longer taking etcd operatons.
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etcdLongTimeout = 30 * time.Second
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// etcdDefaultRootBucketId is used as the root bucket key. Note that
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// the actual key is not visible, since all bucket keys are hashed.
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etcdDefaultRootBucketId = "@"
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)
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// callerStats holds commit stats for a specific caller. Currently it only
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// holds the max stat, meaning that for a particular caller the largest
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// commit set is recorded.
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type callerStats struct {
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count int
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commitStats CommitStats
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}
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func (s callerStats) String() string {
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return fmt.Sprintf("count: %d, retries: %d, rset: %d, wset: %d",
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s.count, s.commitStats.Retries, s.commitStats.Rset,
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s.commitStats.Wset)
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}
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// commitStatsCollector collects commit stats for commits succeeding
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// and also for commits failing.
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type commitStatsCollector struct {
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sync.RWMutex
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succ map[string]*callerStats
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fail map[string]*callerStats
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}
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// newCommitStatsColletor creates a new commitStatsCollector instance.
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func newCommitStatsColletor() *commitStatsCollector {
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return &commitStatsCollector{
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succ: make(map[string]*callerStats),
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fail: make(map[string]*callerStats),
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}
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}
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// PrintStats returns collected stats pretty printed into a string.
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func (c *commitStatsCollector) PrintStats() string {
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c.RLock()
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defer c.RUnlock()
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s := "\nFailure:\n"
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for k, v := range c.fail {
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s += fmt.Sprintf("%s\t%s\n", k, v)
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}
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s += "\nSuccess:\n"
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for k, v := range c.succ {
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s += fmt.Sprintf("%s\t%s\n", k, v)
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}
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return s
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}
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// updateStatsMap updatess commit stats map for a caller.
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func updateStatMap(
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caller string, stats CommitStats, m map[string]*callerStats) {
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if _, ok := m[caller]; !ok {
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m[caller] = &callerStats{}
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}
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curr := m[caller]
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curr.count++
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// Update only if the total commit set is greater or equal.
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currTotal := curr.commitStats.Rset + curr.commitStats.Wset
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if currTotal <= (stats.Rset + stats.Wset) {
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curr.commitStats = stats
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}
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}
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// callback is an STM commit stats callback passed which can be passed
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// using a WithCommitStatsCallback to the STM upon construction.
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func (c *commitStatsCollector) callback(succ bool, stats CommitStats) {
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caller := "unknown"
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// Get the caller. As this callback is called from
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// the backend interface that means we need to ascend
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// 4 frames in the callstack.
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_, file, no, ok := runtime.Caller(4)
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if ok {
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caller = fmt.Sprintf("%s#%d", file, no)
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}
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c.Lock()
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defer c.Unlock()
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if succ {
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updateStatMap(caller, stats, c.succ)
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} else {
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updateStatMap(caller, stats, c.fail)
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}
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}
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// db holds a reference to the etcd client connection.
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type db struct {
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cfg Config
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ctx context.Context
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cli *clientv3.Client
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commitStatsCollector *commitStatsCollector
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txQueue *commitQueue
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}
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// Enforce db implements the walletdb.DB interface.
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var _ walletdb.DB = (*db)(nil)
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// newEtcdBackend returns a db object initialized with the passed backend
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// config. If etcd connection cannot be estabished, then returns error.
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func newEtcdBackend(ctx context.Context, cfg Config) (*db, error) {
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clientCfg := clientv3.Config{
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Context: ctx,
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Endpoints: []string{cfg.Host},
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DialTimeout: etcdConnectionTimeout,
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Username: cfg.User,
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Password: cfg.Pass,
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MaxCallSendMsgSize: 16384*1024 - 1,
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}
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if !cfg.DisableTLS {
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tlsInfo := transport.TLSInfo{
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CertFile: cfg.CertFile,
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KeyFile: cfg.KeyFile,
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InsecureSkipVerify: cfg.InsecureSkipVerify,
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}
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tlsConfig, err := tlsInfo.ClientConfig()
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if err != nil {
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return nil, err
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}
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clientCfg.TLS = tlsConfig
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}
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cli, err := clientv3.New(clientCfg)
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if err != nil {
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return nil, err
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}
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// Apply the namespace.
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cli.KV = namespace.NewKV(cli.KV, cfg.Namespace)
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cli.Watcher = namespace.NewWatcher(cli.Watcher, cfg.Namespace)
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cli.Lease = namespace.NewLease(cli.Lease, cfg.Namespace)
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backend := &db{
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cfg: cfg,
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ctx: ctx,
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cli: cli,
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txQueue: NewCommitQueue(ctx),
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}
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if cfg.CollectStats {
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backend.commitStatsCollector = newCommitStatsColletor()
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}
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return backend, nil
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}
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// getSTMOptions creats all STM options based on the backend config.
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func (db *db) getSTMOptions() []STMOptionFunc {
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opts := []STMOptionFunc{
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WithAbortContext(db.ctx),
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}
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if db.cfg.CollectStats {
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opts = append(opts,
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WithCommitStatsCallback(db.commitStatsCollector.callback),
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)
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}
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return opts
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}
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// View opens a database read transaction and executes the function f with the
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// transaction passed as a parameter. After f exits, the transaction is rolled
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// back. If f errors, its error is returned, not a rollback error (if any
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// occur). The passed reset function is called before the start of the
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// transaction and can be used to reset intermediate state. As callers may
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// expect retries of the f closure (depending on the database backend used), the
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// reset function will be called before each retry respectively.
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func (db *db) View(f func(tx walletdb.ReadTx) error, reset func()) error {
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apply := func(stm STM) error {
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reset()
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return f(newReadWriteTx(stm, etcdDefaultRootBucketId))
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}
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return RunSTM(db.cli, apply, db.txQueue, db.getSTMOptions()...)
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}
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// Update opens a database read/write transaction and executes the function f
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// with the transaction passed as a parameter. After f exits, if f did not
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// error, the transaction is committed. Otherwise, if f did error, the
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// transaction is rolled back. If the rollback fails, the original error
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// returned by f is still returned. If the commit fails, the commit error is
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// returned. As callers may expect retries of the f closure, the reset function
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// will be called before each retry respectively.
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func (db *db) Update(f func(tx walletdb.ReadWriteTx) error, reset func()) error {
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apply := func(stm STM) error {
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reset()
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return f(newReadWriteTx(stm, etcdDefaultRootBucketId))
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}
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return RunSTM(db.cli, apply, db.txQueue, db.getSTMOptions()...)
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}
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// PrintStats returns all collected stats pretty printed into a string.
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func (db *db) PrintStats() string {
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if db.commitStatsCollector != nil {
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return db.commitStatsCollector.PrintStats()
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}
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return ""
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}
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// BeginReadWriteTx opens a database read+write transaction.
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func (db *db) BeginReadWriteTx() (walletdb.ReadWriteTx, error) {
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return newReadWriteTx(
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NewSTM(db.cli, db.txQueue, db.getSTMOptions()...),
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etcdDefaultRootBucketId,
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), nil
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}
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// BeginReadTx opens a database read transaction.
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func (db *db) BeginReadTx() (walletdb.ReadTx, error) {
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return newReadWriteTx(
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NewSTM(db.cli, db.txQueue, db.getSTMOptions()...),
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etcdDefaultRootBucketId,
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), nil
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}
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// Copy writes a copy of the database to the provided writer. This call will
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// start a read-only transaction to perform all operations.
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// This function is part of the walletdb.Db interface implementation.
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func (db *db) Copy(w io.Writer) error {
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ctx, cancel := context.WithTimeout(db.ctx, etcdLongTimeout)
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defer cancel()
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readCloser, err := db.cli.Snapshot(ctx)
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if err != nil {
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return err
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}
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_, err = io.Copy(w, readCloser)
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return err
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}
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// Close cleanly shuts down the database and syncs all data.
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// This function is part of the walletdb.Db interface implementation.
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func (db *db) Close() error {
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return db.cli.Close()
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}
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