724ca7a358
Since bbolt uses syscalls for memory mapping that aren't available in JS/WASM builds, we need to make sure we don't reference that code at all. Otherwise we can't use parts of lnd as a library in projects that are being compiled down to a WASM binary.
271 lines
8.4 KiB
Go
271 lines
8.4 KiB
Go
// +build !js
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package kvdb
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import (
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"context"
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"encoding/binary"
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"time"
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_ "github.com/btcsuite/btcwallet/walletdb/bdb" // Import to register backend.
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)
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const (
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// DefaultTempDBFileName is the default name of the temporary bolt DB
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// file that we'll use to atomically compact the primary DB file on
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// startup.
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DefaultTempDBFileName = "temp-dont-use.db"
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// LastCompactionFileNameSuffix is the suffix we append to the file name
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// of a database file to record the timestamp when the last compaction
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// occurred.
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LastCompactionFileNameSuffix = ".last-compacted"
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)
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var (
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byteOrder = binary.BigEndian
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)
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// fileExists returns true if the file exists, and false otherwise.
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func fileExists(path string) bool {
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if _, err := os.Stat(path); err != nil {
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if os.IsNotExist(err) {
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return false
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}
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}
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return true
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}
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// BoltBackendConfig is a struct that holds settings specific to the bolt
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// database backend.
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type BoltBackendConfig struct {
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// DBPath is the directory path in which the database file should be
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// stored.
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DBPath string
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// DBFileName is the name of the database file.
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DBFileName string
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// NoFreelistSync, if true, prevents the database from syncing its
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// freelist to disk, resulting in improved performance at the expense of
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// increased startup time.
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NoFreelistSync bool
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// AutoCompact specifies if a Bolt based database backend should be
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// automatically compacted on startup (if the minimum age of the
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// database file is reached). This will require additional disk space
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// for the compacted copy of the database but will result in an overall
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// lower database size after the compaction.
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AutoCompact bool
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// AutoCompactMinAge specifies the minimum time that must have passed
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// since a bolt database file was last compacted for the compaction to
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// be considered again.
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AutoCompactMinAge time.Duration
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// DBTimeout specifies the timeout value to use when opening the wallet
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// database.
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DBTimeout time.Duration
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}
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// GetBoltBackend opens (or creates if doesn't exits) a bbolt backed database
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// and returns a kvdb.Backend wrapping it.
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func GetBoltBackend(cfg *BoltBackendConfig) (Backend, error) {
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dbFilePath := filepath.Join(cfg.DBPath, cfg.DBFileName)
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// Is this a new database?
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if !fileExists(dbFilePath) {
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if !fileExists(cfg.DBPath) {
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if err := os.MkdirAll(cfg.DBPath, 0700); err != nil {
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return nil, err
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}
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}
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return Create(
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BoltBackendName, dbFilePath,
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cfg.NoFreelistSync, cfg.DBTimeout,
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)
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}
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// This is an existing database. We might want to compact it on startup
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// to free up some space.
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if cfg.AutoCompact {
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if err := compactAndSwap(cfg); err != nil {
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return nil, err
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}
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}
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return Open(
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BoltBackendName, dbFilePath,
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cfg.NoFreelistSync, cfg.DBTimeout,
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)
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}
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// compactAndSwap will attempt to write a new temporary DB file to disk with
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// the compacted database content, then atomically swap (via rename) the old
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// file for the new file by updating the name of the new file to the old.
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func compactAndSwap(cfg *BoltBackendConfig) error {
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sourceName := cfg.DBFileName
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// If the main DB file isn't set, then we can't proceed.
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if sourceName == "" {
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return fmt.Errorf("cannot compact DB with empty name")
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}
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sourceFilePath := filepath.Join(cfg.DBPath, sourceName)
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tempDestFilePath := filepath.Join(cfg.DBPath, DefaultTempDBFileName)
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// Let's find out how long ago the last compaction of the source file
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// occurred and possibly skip compacting it again now.
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lastCompactionDate, err := lastCompactionDate(sourceFilePath)
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if err != nil {
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return fmt.Errorf("cannot determine last compaction date of "+
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"source DB file: %v", err)
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}
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compactAge := time.Since(lastCompactionDate)
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if cfg.AutoCompactMinAge != 0 && compactAge <= cfg.AutoCompactMinAge {
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log.Infof("Not compacting database file at %v, it was last "+
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"compacted at %v (%v ago), min age is set to %v",
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sourceFilePath, lastCompactionDate,
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compactAge.Truncate(time.Second), cfg.AutoCompactMinAge)
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return nil
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}
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log.Infof("Compacting database file at %v", sourceFilePath)
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// If the old temporary DB file still exists, then we'll delete it
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// before proceeding.
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if _, err := os.Stat(tempDestFilePath); err == nil {
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log.Infof("Found old temp DB @ %v, removing before swap",
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tempDestFilePath)
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err = os.Remove(tempDestFilePath)
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if err != nil {
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return fmt.Errorf("unable to remove old temp DB file: "+
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"%v", err)
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}
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}
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// Now that we know the staging area is clear, we'll create the new
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// temporary DB file and close it before we write the new DB to it.
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tempFile, err := os.Create(tempDestFilePath)
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if err != nil {
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return fmt.Errorf("unable to create temp DB file: %v", err)
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}
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if err := tempFile.Close(); err != nil {
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return fmt.Errorf("unable to close file: %v", err)
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}
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// With the file created, we'll start the compaction and remove the
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// temporary file all together once this method exits.
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defer func() {
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// This will only succeed if the rename below fails. If the
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// compaction is successful, the file won't exist on exit
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// anymore so no need to log an error here.
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_ = os.Remove(tempDestFilePath)
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}()
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c := &compacter{
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srcPath: sourceFilePath,
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dstPath: tempDestFilePath,
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dbTimeout: cfg.DBTimeout,
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}
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initialSize, newSize, err := c.execute()
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if err != nil {
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return fmt.Errorf("error during compact: %v", err)
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}
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log.Infof("DB compaction of %v successful, %d -> %d bytes (gain=%.2fx)",
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sourceFilePath, initialSize, newSize,
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float64(initialSize)/float64(newSize))
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// We try to store the current timestamp in a file with the suffix
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// .last-compacted so we can figure out how long ago the last compaction
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// was. But since this shouldn't fail the compaction process itself, we
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// only log the error. Worst case if this file cannot be written is that
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// we compact on every startup.
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err = updateLastCompactionDate(sourceFilePath)
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if err != nil {
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log.Warnf("Could not update last compaction timestamp in "+
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"%s%s: %v", sourceFilePath,
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LastCompactionFileNameSuffix, err)
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}
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log.Infof("Swapping old DB file from %v to %v", tempDestFilePath,
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sourceFilePath)
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// Finally, we'll attempt to atomically rename the temporary file to
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// the main back up file. If this succeeds, then we'll only have a
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// single file on disk once this method exits.
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return os.Rename(tempDestFilePath, sourceFilePath)
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}
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// lastCompactionDate returns the date the given database file was last
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// compacted or a zero time.Time if no compaction was recorded before. The
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// compaction date is read from a file in the same directory and with the same
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// name as the DB file, but with the suffix ".last-compacted".
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func lastCompactionDate(dbFile string) (time.Time, error) {
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zeroTime := time.Unix(0, 0)
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tsFile := fmt.Sprintf("%s%s", dbFile, LastCompactionFileNameSuffix)
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if !fileExists(tsFile) {
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return zeroTime, nil
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}
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tsBytes, err := ioutil.ReadFile(tsFile)
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if err != nil {
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return zeroTime, err
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}
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tsNano := byteOrder.Uint64(tsBytes)
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return time.Unix(0, int64(tsNano)), nil
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}
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// updateLastCompactionDate stores the current time as a timestamp in a file
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// in the same directory and with the same name as the DB file, but with the
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// suffix ".last-compacted".
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func updateLastCompactionDate(dbFile string) error {
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var tsBytes [8]byte
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byteOrder.PutUint64(tsBytes[:], uint64(time.Now().UnixNano()))
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tsFile := fmt.Sprintf("%s%s", dbFile, LastCompactionFileNameSuffix)
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return ioutil.WriteFile(tsFile, tsBytes[:], 0600)
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}
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// GetTestBackend opens (or creates if doesn't exist) a bbolt or etcd
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// backed database (for testing), and returns a kvdb.Backend and a cleanup
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// func. Whether to create/open bbolt or embedded etcd database is based
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// on the TestBackend constant which is conditionally compiled with build tag.
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// The passed path is used to hold all db files, while the name is only used
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// for bbolt.
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func GetTestBackend(path, name string) (Backend, func(), error) {
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empty := func() {}
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if TestBackend == BoltBackendName {
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db, err := GetBoltBackend(&BoltBackendConfig{
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DBPath: path,
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DBFileName: name,
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NoFreelistSync: true,
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DBTimeout: DefaultDBTimeout,
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})
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if err != nil {
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return nil, nil, err
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}
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return db, empty, nil
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} else if TestBackend == EtcdBackendName {
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etcdConfig, cancel, err := StartEtcdTestBackend(path, 0, 0)
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if err != nil {
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return nil, empty, err
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}
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backend, err := Open(
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EtcdBackendName, context.TODO(), etcdConfig,
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)
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return backend, cancel, err
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}
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return nil, nil, fmt.Errorf("unknown backend")
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}
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