lnd.xprv/channeldb/kvdb/etcd/db.go

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// +build kvdb_etcd
package etcd
import (
"context"
"fmt"
"io"
"runtime"
"sync"
"time"
"github.com/btcsuite/btcwallet/walletdb"
"github.com/coreos/etcd/clientv3"
"github.com/coreos/etcd/pkg/transport"
)
const (
// etcdConnectionTimeout is the timeout until successful connection to the
// etcd instance.
etcdConnectionTimeout = 10 * time.Second
// etcdLongTimeout is a timeout for longer taking etcd operatons.
etcdLongTimeout = 30 * time.Second
)
// callerStats holds commit stats for a specific caller. Currently it only
// holds the max stat, meaning that for a particular caller the largest
// commit set is recorded.
type callerStats struct {
count int
commitStats CommitStats
}
func (s callerStats) String() string {
return fmt.Sprintf("count: %d, retries: %d, rset: %d, wset: %d",
s.count, s.commitStats.Retries, s.commitStats.Rset, s.commitStats.Wset)
}
// commitStatsCollector collects commit stats for commits succeeding
// and also for commits failing.
type commitStatsCollector struct {
sync.RWMutex
succ map[string]*callerStats
fail map[string]*callerStats
}
// newCommitStatsColletor creates a new commitStatsCollector instance.
func newCommitStatsColletor() *commitStatsCollector {
return &commitStatsCollector{
succ: make(map[string]*callerStats),
fail: make(map[string]*callerStats),
}
}
// PrintStats returns collected stats pretty printed into a string.
func (c *commitStatsCollector) PrintStats() string {
c.RLock()
defer c.RUnlock()
s := "\nFailure:\n"
for k, v := range c.fail {
s += fmt.Sprintf("%s\t%s\n", k, v)
}
s += "\nSuccess:\n"
for k, v := range c.succ {
s += fmt.Sprintf("%s\t%s\n", k, v)
}
return s
}
// updateStatsMap updatess commit stats map for a caller.
func updateStatMap(
caller string, stats CommitStats, m map[string]*callerStats) {
if _, ok := m[caller]; !ok {
m[caller] = &callerStats{}
}
curr := m[caller]
curr.count++
// Update only if the total commit set is greater or equal.
currTotal := curr.commitStats.Rset + curr.commitStats.Wset
if currTotal <= (stats.Rset + stats.Wset) {
curr.commitStats = stats
}
}
// callback is an STM commit stats callback passed which can be passed
// using a WithCommitStatsCallback to the STM upon construction.
func (c *commitStatsCollector) callback(succ bool, stats CommitStats) {
caller := "unknown"
// Get the caller. As this callback is called from
// the backend interface that means we need to ascend
// 4 frames in the callstack.
_, file, no, ok := runtime.Caller(4)
if ok {
caller = fmt.Sprintf("%s#%d", file, no)
}
c.Lock()
defer c.Unlock()
if succ {
updateStatMap(caller, stats, c.succ)
} else {
updateStatMap(caller, stats, c.fail)
}
}
// db holds a reference to the etcd client connection.
type db struct {
config BackendConfig
cli *clientv3.Client
commitStatsCollector *commitStatsCollector
}
// Enforce db implements the walletdb.DB interface.
var _ walletdb.DB = (*db)(nil)
// BackendConfig holds and etcd backend config and connection parameters.
type BackendConfig struct {
// Host holds the peer url of the etcd instance.
Host string
// User is the username for the etcd peer.
User string
// Pass is the password for the etcd peer.
Pass string
// CertFile holds the path to the TLS certificate for etcd RPC.
CertFile string
// KeyFile holds the path to the TLS private key for etcd RPC.
KeyFile string
// InsecureSkipVerify should be set to true if we intend to
// skip TLS verification.
InsecureSkipVerify bool
// Prefix the hash of the prefix will be used as the root
// bucket id. This enables key space separation similar to
// name spaces.
Prefix string
// CollectCommitStats indicates wheter to commit commit stats.
CollectCommitStats bool
}
// newEtcdBackend returns a db object initialized with the passed backend
// config. If etcd connection cannot be estabished, then returns error.
func newEtcdBackend(config BackendConfig) (*db, error) {
tlsInfo := transport.TLSInfo{
CertFile: config.CertFile,
KeyFile: config.KeyFile,
InsecureSkipVerify: config.InsecureSkipVerify,
}
tlsConfig, err := tlsInfo.ClientConfig()
if err != nil {
return nil, err
}
cli, err := clientv3.New(clientv3.Config{
Endpoints: []string{config.Host},
DialTimeout: etcdConnectionTimeout,
Username: config.User,
Password: config.Pass,
TLS: tlsConfig,
})
if err != nil {
return nil, err
}
backend := &db{
cli: cli,
config: config,
}
if config.CollectCommitStats {
backend.commitStatsCollector = newCommitStatsColletor()
}
return backend, nil
}
// getSTMOptions creats all STM options based on the backend config.
func (db *db) getSTMOptions() []STMOptionFunc {
opts := []STMOptionFunc{}
if db.config.CollectCommitStats {
opts = append(opts,
WithCommitStatsCallback(db.commitStatsCollector.callback),
)
}
return opts
}
// View opens a database read transaction and executes the function f with the
// transaction passed as a parameter. After f exits, the transaction is rolled
// back. If f errors, its error is returned, not a rollback error (if any
// occur).
func (db *db) View(f func(tx walletdb.ReadTx) error) error {
apply := func(stm STM) error {
return f(newReadWriteTx(stm, db.config.Prefix))
}
return RunSTM(db.cli, apply, db.getSTMOptions()...)
}
// Update opens a database read/write transaction and executes the function f
// with the transaction passed as a parameter. After f exits, if f did not
// error, the transaction is committed. Otherwise, if f did error, the
// transaction is rolled back. If the rollback fails, the original error
// returned by f is still returned. If the commit fails, the commit error is
// returned.
func (db *db) Update(f func(tx walletdb.ReadWriteTx) error) error {
apply := func(stm STM) error {
return f(newReadWriteTx(stm, db.config.Prefix))
}
return RunSTM(db.cli, apply, db.getSTMOptions()...)
}
// PrintStats returns all collected stats pretty printed into a string.
func (db *db) PrintStats() string {
if db.commitStatsCollector != nil {
return db.commitStatsCollector.PrintStats()
}
return ""
}
// BeginReadTx opens a database read transaction.
func (db *db) BeginReadWriteTx() (walletdb.ReadWriteTx, error) {
return newReadWriteTx(
NewSTM(db.cli, db.getSTMOptions()...),
db.config.Prefix,
), nil
}
// BeginReadWriteTx opens a database read+write transaction.
func (db *db) BeginReadTx() (walletdb.ReadTx, error) {
return newReadWriteTx(
NewSTM(db.cli, db.getSTMOptions()...),
db.config.Prefix,
), nil
}
// Copy writes a copy of the database to the provided writer. This call will
// start a read-only transaction to perform all operations.
// This function is part of the walletdb.Db interface implementation.
func (db *db) Copy(w io.Writer) error {
ctx := context.Background()
ctx, cancel := context.WithTimeout(ctx, etcdLongTimeout)
defer cancel()
readCloser, err := db.cli.Snapshot(ctx)
if err != nil {
return err
}
_, err = io.Copy(w, readCloser)
return err
}
// Close cleanly shuts down the database and syncs all data.
// This function is part of the walletdb.Db interface implementation.
func (db *db) Close() error {
return db.cli.Close()
}
// Batch opens a database read/write transaction and executes the function f
// with the transaction passed as a parameter. After f exits, if f did not
// error, the transaction is committed. Otherwise, if f did error, the
// transaction is rolled back. If the rollback fails, the original error
// returned by f is still returned. If the commit fails, the commit error is
// returned.
//
// Batch is only useful when there are multiple goroutines calling it.
func (db *db) Batch(apply func(tx walletdb.ReadWriteTx) error) error {
return db.Update(apply)
}