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provider.go
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provider.go
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/*
Package files defines a Provider that stores all data in the filesystem
We assume the same validator hash may be reused by many different
headers/Commits, and thus store it separately. This leaves us
with three issues:
1. Given a validator hash, retrieve the validator set if previously stored
2. Given a block height, find the Commit with the highest height <= h
3. Given a FullCommit, store it quickly to satisfy 1 and 2
Note that we do not worry about caching, as that can be achieved by
pairing this with a MemStoreProvider and CacheProvider from certifiers
*/
package files
import (
"encoding/hex"
"fmt"
"math"
"os"
"path/filepath"
"sort"
"github.com/pkg/errors"
"github.com/tendermint/tendermint/lite"
liteErr "github.com/tendermint/tendermint/lite/errors"
)
// nolint
const (
Ext = ".tsd"
ValDir = "validators"
CheckDir = "checkpoints"
dirPerm = os.FileMode(0755)
//filePerm = os.FileMode(0644)
)
type provider struct {
valDir string
checkDir string
}
// NewProvider creates the parent dir and subdirs
// for validators and checkpoints as needed
func NewProvider(dir string) lite.Provider {
valDir := filepath.Join(dir, ValDir)
checkDir := filepath.Join(dir, CheckDir)
for _, d := range []string{valDir, checkDir} {
err := os.MkdirAll(d, dirPerm)
if err != nil {
panic(err)
}
}
return &provider{valDir: valDir, checkDir: checkDir}
}
func (p *provider) encodeHash(hash []byte) string {
return hex.EncodeToString(hash) + Ext
}
func (p *provider) encodeHeight(h int64) string {
// pad up to 10^12 for height...
return fmt.Sprintf("%012d%s", h, Ext)
}
// StoreCommit saves a full commit after it has been verified.
func (p *provider) StoreCommit(fc lite.FullCommit) error {
// make sure the fc is self-consistent before saving
err := fc.ValidateBasic(fc.Commit.Header.ChainID)
if err != nil {
return err
}
paths := []string{
filepath.Join(p.checkDir, p.encodeHeight(fc.Height())),
filepath.Join(p.valDir, p.encodeHash(fc.Header.ValidatorsHash)),
}
for _, path := range paths {
err := SaveFullCommit(fc, path)
// unknown error in creating or writing immediately breaks
if err != nil {
return err
}
}
return nil
}
// GetByHeight returns the closest commit with height <= h.
func (p *provider) GetByHeight(h int64) (lite.FullCommit, error) {
// first we look for exact match, then search...
path := filepath.Join(p.checkDir, p.encodeHeight(h))
fc, err := LoadFullCommit(path)
if liteErr.IsCommitNotFoundErr(err) {
path, err = p.searchForHeight(h)
if err == nil {
fc, err = LoadFullCommit(path)
}
}
return fc, err
}
// LatestCommit returns the newest commit stored.
func (p *provider) LatestCommit() (fc lite.FullCommit, err error) {
// Note to future: please update by 2077 to avoid rollover
return p.GetByHeight(math.MaxInt32 - 1)
}
// search for height, looks for a file with highest height < h
// return certifiers.ErrCommitNotFound() if not there...
func (p *provider) searchForHeight(h int64) (string, error) {
d, err := os.Open(p.checkDir)
if err != nil {
return "", errors.WithStack(err)
}
files, err := d.Readdirnames(0)
d.Close()
if err != nil {
return "", errors.WithStack(err)
}
desired := p.encodeHeight(h)
sort.Strings(files)
i := sort.SearchStrings(files, desired)
if i == 0 {
return "", liteErr.ErrCommitNotFound()
}
found := files[i-1]
path := filepath.Join(p.checkDir, found)
return path, errors.WithStack(err)
}
// GetByHash returns a commit exactly matching this validator hash.
func (p *provider) GetByHash(hash []byte) (lite.FullCommit, error) {
path := filepath.Join(p.valDir, p.encodeHash(hash))
return LoadFullCommit(path)
}