plugeth/core/rawdb/freezer_table.go
Felix Lange 193f350eb9
core/rawdb: improve freezerTable.Sync (#26245)
While investigating #22374, I noticed that the Sync operation of the
freezer does not take the table lock. It also doesn't call sync for all files
if there is an error with one of them. I doubt this will fix anything, but
didn't want to drop the fix on the floor either.
2022-11-24 10:50:28 +01:00

923 lines
29 KiB
Go

// Copyright 2019 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rawdb
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"sync"
"sync/atomic"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/golang/snappy"
)
var (
// errClosed is returned if an operation attempts to read from or write to the
// freezer table after it has already been closed.
errClosed = errors.New("closed")
// errOutOfBounds is returned if the item requested is not contained within the
// freezer table.
errOutOfBounds = errors.New("out of bounds")
// errNotSupported is returned if the database doesn't support the required operation.
errNotSupported = errors.New("this operation is not supported")
)
// indexEntry contains the number/id of the file that the data resides in, as well as the
// offset within the file to the end of the data.
// In serialized form, the filenum is stored as uint16.
type indexEntry struct {
filenum uint32 // stored as uint16 ( 2 bytes )
offset uint32 // stored as uint32 ( 4 bytes )
}
const indexEntrySize = 6
// unmarshalBinary deserializes binary b into the rawIndex entry.
func (i *indexEntry) unmarshalBinary(b []byte) {
i.filenum = uint32(binary.BigEndian.Uint16(b[:2]))
i.offset = binary.BigEndian.Uint32(b[2:6])
}
// append adds the encoded entry to the end of b.
func (i *indexEntry) append(b []byte) []byte {
offset := len(b)
out := append(b, make([]byte, indexEntrySize)...)
binary.BigEndian.PutUint16(out[offset:], uint16(i.filenum))
binary.BigEndian.PutUint32(out[offset+2:], i.offset)
return out
}
// bounds returns the start- and end- offsets, and the file number of where to
// read there data item marked by the two index entries. The two entries are
// assumed to be sequential.
func (i *indexEntry) bounds(end *indexEntry) (startOffset, endOffset, fileId uint32) {
if i.filenum != end.filenum {
// If a piece of data 'crosses' a data-file,
// it's actually in one piece on the second data-file.
// We return a zero-indexEntry for the second file as start
return 0, end.offset, end.filenum
}
return i.offset, end.offset, end.filenum
}
// freezerTable represents a single chained data table within the freezer (e.g. blocks).
// It consists of a data file (snappy encoded arbitrary data blobs) and an indexEntry
// file (uncompressed 64 bit indices into the data file).
type freezerTable struct {
// WARNING: The `items` field is accessed atomically. On 32 bit platforms, only
// 64-bit aligned fields can be atomic. The struct is guaranteed to be so aligned,
// so take advantage of that (https://golang.org/pkg/sync/atomic/#pkg-note-BUG).
items uint64 // Number of items stored in the table (including items removed from tail)
itemOffset uint64 // Number of items removed from the table
// itemHidden is the number of items marked as deleted. Tail deletion is
// only supported at file level which means the actual deletion will be
// delayed until the entire data file is marked as deleted. Before that
// these items will be hidden to prevent being visited again. The value
// should never be lower than itemOffset.
itemHidden uint64
noCompression bool // if true, disables snappy compression. Note: does not work retroactively
readonly bool
maxFileSize uint32 // Max file size for data-files
name string
path string
head *os.File // File descriptor for the data head of the table
index *os.File // File descriptor for the indexEntry file of the table
meta *os.File // File descriptor for metadata of the table
files map[uint32]*os.File // open files
headId uint32 // number of the currently active head file
tailId uint32 // number of the earliest file
headBytes int64 // Number of bytes written to the head file
readMeter metrics.Meter // Meter for measuring the effective amount of data read
writeMeter metrics.Meter // Meter for measuring the effective amount of data written
sizeGauge metrics.Gauge // Gauge for tracking the combined size of all freezer tables
logger log.Logger // Logger with database path and table name embedded
lock sync.RWMutex // Mutex protecting the data file descriptors
}
// newFreezerTable opens the given path as a freezer table.
func newFreezerTable(path, name string, disableSnappy, readonly bool) (*freezerTable, error) {
return newTable(path, name, metrics.NilMeter{}, metrics.NilMeter{}, metrics.NilGauge{}, freezerTableSize, disableSnappy, readonly)
}
// newTable opens a freezer table, creating the data and index files if they are
// non-existent. Both files are truncated to the shortest common length to ensure
// they don't go out of sync.
func newTable(path string, name string, readMeter metrics.Meter, writeMeter metrics.Meter, sizeGauge metrics.Gauge, maxFilesize uint32, noCompression, readonly bool) (*freezerTable, error) {
// Ensure the containing directory exists and open the indexEntry file
if err := os.MkdirAll(path, 0755); err != nil {
return nil, err
}
var idxName string
if noCompression {
idxName = fmt.Sprintf("%s.ridx", name) // raw index file
} else {
idxName = fmt.Sprintf("%s.cidx", name) // compressed index file
}
var (
err error
index *os.File
meta *os.File
)
if readonly {
// Will fail if table index file or meta file is not existent
index, err = openFreezerFileForReadOnly(filepath.Join(path, idxName))
if err != nil {
return nil, err
}
meta, err = openFreezerFileForReadOnly(filepath.Join(path, fmt.Sprintf("%s.meta", name)))
if err != nil {
return nil, err
}
} else {
index, err = openFreezerFileForAppend(filepath.Join(path, idxName))
if err != nil {
return nil, err
}
meta, err = openFreezerFileForAppend(filepath.Join(path, fmt.Sprintf("%s.meta", name)))
if err != nil {
return nil, err
}
}
// Create the table and repair any past inconsistency
tab := &freezerTable{
index: index,
meta: meta,
files: make(map[uint32]*os.File),
readMeter: readMeter,
writeMeter: writeMeter,
sizeGauge: sizeGauge,
name: name,
path: path,
logger: log.New("database", path, "table", name),
noCompression: noCompression,
readonly: readonly,
maxFileSize: maxFilesize,
}
if err := tab.repair(); err != nil {
tab.Close()
return nil, err
}
// Initialize the starting size counter
size, err := tab.sizeNolock()
if err != nil {
tab.Close()
return nil, err
}
tab.sizeGauge.Inc(int64(size))
return tab, nil
}
// repair cross-checks the head and the index file and truncates them to
// be in sync with each other after a potential crash / data loss.
func (t *freezerTable) repair() error {
// Create a temporary offset buffer to init files with and read indexEntry into
buffer := make([]byte, indexEntrySize)
// If we've just created the files, initialize the index with the 0 indexEntry
stat, err := t.index.Stat()
if err != nil {
return err
}
if stat.Size() == 0 {
if _, err := t.index.Write(buffer); err != nil {
return err
}
}
// Ensure the index is a multiple of indexEntrySize bytes
if overflow := stat.Size() % indexEntrySize; overflow != 0 {
truncateFreezerFile(t.index, stat.Size()-overflow) // New file can't trigger this path
}
// Retrieve the file sizes and prepare for truncation
if stat, err = t.index.Stat(); err != nil {
return err
}
offsetsSize := stat.Size()
// Open the head file
var (
firstIndex indexEntry
lastIndex indexEntry
contentSize int64
contentExp int64
)
// Read index zero, determine what file is the earliest
// and what item offset to use
t.index.ReadAt(buffer, 0)
firstIndex.unmarshalBinary(buffer)
// Assign the tail fields with the first stored index.
// The total removed items is represented with an uint32,
// which is not enough in theory but enough in practice.
// TODO: use uint64 to represent total removed items.
t.tailId = firstIndex.filenum
t.itemOffset = uint64(firstIndex.offset)
// Load metadata from the file
meta, err := loadMetadata(t.meta, t.itemOffset)
if err != nil {
return err
}
t.itemHidden = meta.VirtualTail
// Read the last index, use the default value in case the freezer is empty
if offsetsSize == indexEntrySize {
lastIndex = indexEntry{filenum: t.tailId, offset: 0}
} else {
t.index.ReadAt(buffer, offsetsSize-indexEntrySize)
lastIndex.unmarshalBinary(buffer)
}
if t.readonly {
t.head, err = t.openFile(lastIndex.filenum, openFreezerFileForReadOnly)
} else {
t.head, err = t.openFile(lastIndex.filenum, openFreezerFileForAppend)
}
if err != nil {
return err
}
if stat, err = t.head.Stat(); err != nil {
return err
}
contentSize = stat.Size()
// Keep truncating both files until they come in sync
contentExp = int64(lastIndex.offset)
for contentExp != contentSize {
// Truncate the head file to the last offset pointer
if contentExp < contentSize {
t.logger.Warn("Truncating dangling head", "indexed", common.StorageSize(contentExp), "stored", common.StorageSize(contentSize))
if err := truncateFreezerFile(t.head, contentExp); err != nil {
return err
}
contentSize = contentExp
}
// Truncate the index to point within the head file
if contentExp > contentSize {
t.logger.Warn("Truncating dangling indexes", "indexed", common.StorageSize(contentExp), "stored", common.StorageSize(contentSize))
if err := truncateFreezerFile(t.index, offsetsSize-indexEntrySize); err != nil {
return err
}
offsetsSize -= indexEntrySize
// Read the new head index, use the default value in case
// the freezer is already empty.
var newLastIndex indexEntry
if offsetsSize == indexEntrySize {
newLastIndex = indexEntry{filenum: t.tailId, offset: 0}
} else {
t.index.ReadAt(buffer, offsetsSize-indexEntrySize)
newLastIndex.unmarshalBinary(buffer)
}
// We might have slipped back into an earlier head-file here
if newLastIndex.filenum != lastIndex.filenum {
// Release earlier opened file
t.releaseFile(lastIndex.filenum)
if t.head, err = t.openFile(newLastIndex.filenum, openFreezerFileForAppend); err != nil {
return err
}
if stat, err = t.head.Stat(); err != nil {
// TODO, anything more we can do here?
// A data file has gone missing...
return err
}
contentSize = stat.Size()
}
lastIndex = newLastIndex
contentExp = int64(lastIndex.offset)
}
}
// Sync() fails for read-only files on windows.
if !t.readonly {
// Ensure all reparation changes have been written to disk
if err := t.index.Sync(); err != nil {
return err
}
if err := t.head.Sync(); err != nil {
return err
}
if err := t.meta.Sync(); err != nil {
return err
}
}
// Update the item and byte counters and return
t.items = t.itemOffset + uint64(offsetsSize/indexEntrySize-1) // last indexEntry points to the end of the data file
t.headBytes = contentSize
t.headId = lastIndex.filenum
// Delete the leftover files because of head deletion
t.releaseFilesAfter(t.headId, true)
// Delete the leftover files because of tail deletion
t.releaseFilesBefore(t.tailId, true)
// Close opened files and preopen all files
if err := t.preopen(); err != nil {
return err
}
t.logger.Debug("Chain freezer table opened", "items", t.items, "size", common.StorageSize(t.headBytes))
return nil
}
// preopen opens all files that the freezer will need. This method should be called from an init-context,
// since it assumes that it doesn't have to bother with locking
// The rationale for doing preopen is to not have to do it from within Retrieve, thus not needing to ever
// obtain a write-lock within Retrieve.
func (t *freezerTable) preopen() (err error) {
// The repair might have already opened (some) files
t.releaseFilesAfter(0, false)
// Open all except head in RDONLY
for i := t.tailId; i < t.headId; i++ {
if _, err = t.openFile(i, openFreezerFileForReadOnly); err != nil {
return err
}
}
if t.readonly {
t.head, err = t.openFile(t.headId, openFreezerFileForReadOnly)
} else {
// Open head in read/write
t.head, err = t.openFile(t.headId, openFreezerFileForAppend)
}
return err
}
// truncateHead discards any recent data above the provided threshold number.
func (t *freezerTable) truncateHead(items uint64) error {
t.lock.Lock()
defer t.lock.Unlock()
// Ensure the given truncate target falls in the correct range
existing := atomic.LoadUint64(&t.items)
if existing <= items {
return nil
}
if items < atomic.LoadUint64(&t.itemHidden) {
return errors.New("truncation below tail")
}
// We need to truncate, save the old size for metrics tracking
oldSize, err := t.sizeNolock()
if err != nil {
return err
}
// Something's out of sync, truncate the table's offset index
log := t.logger.Debug
if existing > items+1 {
log = t.logger.Warn // Only loud warn if we delete multiple items
}
log("Truncating freezer table", "items", existing, "limit", items)
// Truncate the index file first, the tail position is also considered
// when calculating the new freezer table length.
length := items - atomic.LoadUint64(&t.itemOffset)
if err := truncateFreezerFile(t.index, int64(length+1)*indexEntrySize); err != nil {
return err
}
// Calculate the new expected size of the data file and truncate it
var expected indexEntry
if length == 0 {
expected = indexEntry{filenum: t.tailId, offset: 0}
} else {
buffer := make([]byte, indexEntrySize)
if _, err := t.index.ReadAt(buffer, int64(length*indexEntrySize)); err != nil {
return err
}
expected.unmarshalBinary(buffer)
}
// We might need to truncate back to older files
if expected.filenum != t.headId {
// If already open for reading, force-reopen for writing
t.releaseFile(expected.filenum)
newHead, err := t.openFile(expected.filenum, openFreezerFileForAppend)
if err != nil {
return err
}
// Release any files _after the current head -- both the previous head
// and any files which may have been opened for reading
t.releaseFilesAfter(expected.filenum, true)
// Set back the historic head
t.head = newHead
t.headId = expected.filenum
}
if err := truncateFreezerFile(t.head, int64(expected.offset)); err != nil {
return err
}
// All data files truncated, set internal counters and return
t.headBytes = int64(expected.offset)
atomic.StoreUint64(&t.items, items)
// Retrieve the new size and update the total size counter
newSize, err := t.sizeNolock()
if err != nil {
return err
}
t.sizeGauge.Dec(int64(oldSize - newSize))
return nil
}
// truncateTail discards any recent data before the provided threshold number.
func (t *freezerTable) truncateTail(items uint64) error {
t.lock.Lock()
defer t.lock.Unlock()
// Ensure the given truncate target falls in the correct range
if atomic.LoadUint64(&t.itemHidden) >= items {
return nil
}
if atomic.LoadUint64(&t.items) < items {
return errors.New("truncation above head")
}
// Load the new tail index by the given new tail position
var (
newTailId uint32
buffer = make([]byte, indexEntrySize)
)
if atomic.LoadUint64(&t.items) == items {
newTailId = t.headId
} else {
offset := items - atomic.LoadUint64(&t.itemOffset)
if _, err := t.index.ReadAt(buffer, int64((offset+1)*indexEntrySize)); err != nil {
return err
}
var newTail indexEntry
newTail.unmarshalBinary(buffer)
newTailId = newTail.filenum
}
// Update the virtual tail marker and hidden these entries in table.
atomic.StoreUint64(&t.itemHidden, items)
if err := writeMetadata(t.meta, newMetadata(items)); err != nil {
return err
}
// Hidden items still fall in the current tail file, no data file
// can be dropped.
if t.tailId == newTailId {
return nil
}
// Hidden items fall in the incorrect range, returns the error.
if t.tailId > newTailId {
return fmt.Errorf("invalid index, tail-file %d, item-file %d", t.tailId, newTailId)
}
// Hidden items exceed the current tail file, drop the relevant
// data files. We need to truncate, save the old size for metrics
// tracking.
oldSize, err := t.sizeNolock()
if err != nil {
return err
}
// Count how many items can be deleted from the file.
var (
newDeleted = items
deleted = atomic.LoadUint64(&t.itemOffset)
)
for current := items - 1; current >= deleted; current -= 1 {
if _, err := t.index.ReadAt(buffer, int64((current-deleted+1)*indexEntrySize)); err != nil {
return err
}
var pre indexEntry
pre.unmarshalBinary(buffer)
if pre.filenum != newTailId {
break
}
newDeleted = current
}
// Commit the changes of metadata file first before manipulating
// the indexes file.
if err := t.meta.Sync(); err != nil {
return err
}
// Truncate the deleted index entries from the index file.
err = copyFrom(t.index.Name(), t.index.Name(), indexEntrySize*(newDeleted-deleted+1), func(f *os.File) error {
tailIndex := indexEntry{
filenum: newTailId,
offset: uint32(newDeleted),
}
_, err := f.Write(tailIndex.append(nil))
return err
})
if err != nil {
return err
}
// Reopen the modified index file to load the changes
if err := t.index.Close(); err != nil {
return err
}
t.index, err = openFreezerFileForAppend(t.index.Name())
if err != nil {
return err
}
// Release any files before the current tail
t.tailId = newTailId
atomic.StoreUint64(&t.itemOffset, newDeleted)
t.releaseFilesBefore(t.tailId, true)
// Retrieve the new size and update the total size counter
newSize, err := t.sizeNolock()
if err != nil {
return err
}
t.sizeGauge.Dec(int64(oldSize - newSize))
return nil
}
// Close closes all opened files.
func (t *freezerTable) Close() error {
t.lock.Lock()
defer t.lock.Unlock()
var errs []error
if err := t.index.Close(); err != nil {
errs = append(errs, err)
}
t.index = nil
if err := t.meta.Close(); err != nil {
errs = append(errs, err)
}
t.meta = nil
for _, f := range t.files {
if err := f.Close(); err != nil {
errs = append(errs, err)
}
}
t.head = nil
if errs != nil {
return fmt.Errorf("%v", errs)
}
return nil
}
// openFile assumes that the write-lock is held by the caller
func (t *freezerTable) openFile(num uint32, opener func(string) (*os.File, error)) (f *os.File, err error) {
var exist bool
if f, exist = t.files[num]; !exist {
var name string
if t.noCompression {
name = fmt.Sprintf("%s.%04d.rdat", t.name, num)
} else {
name = fmt.Sprintf("%s.%04d.cdat", t.name, num)
}
f, err = opener(filepath.Join(t.path, name))
if err != nil {
return nil, err
}
t.files[num] = f
}
return f, err
}
// releaseFile closes a file, and removes it from the open file cache.
// Assumes that the caller holds the write lock
func (t *freezerTable) releaseFile(num uint32) {
if f, exist := t.files[num]; exist {
delete(t.files, num)
f.Close()
}
}
// releaseFilesAfter closes all open files with a higher number, and optionally also deletes the files
func (t *freezerTable) releaseFilesAfter(num uint32, remove bool) {
for fnum, f := range t.files {
if fnum > num {
delete(t.files, fnum)
f.Close()
if remove {
os.Remove(f.Name())
}
}
}
}
// releaseFilesBefore closes all open files with a lower number, and optionally also deletes the files
func (t *freezerTable) releaseFilesBefore(num uint32, remove bool) {
for fnum, f := range t.files {
if fnum < num {
delete(t.files, fnum)
f.Close()
if remove {
os.Remove(f.Name())
}
}
}
}
// getIndices returns the index entries for the given from-item, covering 'count' items.
// N.B: The actual number of returned indices for N items will always be N+1 (unless an
// error is returned).
// OBS: This method assumes that the caller has already verified (and/or trimmed) the range
// so that the items are within bounds. If this method is used to read out of bounds,
// it will return error.
func (t *freezerTable) getIndices(from, count uint64) ([]*indexEntry, error) {
// Apply the table-offset
from = from - t.itemOffset
// For reading N items, we need N+1 indices.
buffer := make([]byte, (count+1)*indexEntrySize)
if _, err := t.index.ReadAt(buffer, int64(from*indexEntrySize)); err != nil {
return nil, err
}
var (
indices []*indexEntry
offset int
)
for i := from; i <= from+count; i++ {
index := new(indexEntry)
index.unmarshalBinary(buffer[offset:])
offset += indexEntrySize
indices = append(indices, index)
}
if from == 0 {
// Special case if we're reading the first item in the freezer. We assume that
// the first item always start from zero(regarding the deletion, we
// only support deletion by files, so that the assumption is held).
// This means we can use the first item metadata to carry information about
// the 'global' offset, for the deletion-case
indices[0].offset = 0
indices[0].filenum = indices[1].filenum
}
return indices, nil
}
// Retrieve looks up the data offset of an item with the given number and retrieves
// the raw binary blob from the data file.
func (t *freezerTable) Retrieve(item uint64) ([]byte, error) {
items, err := t.RetrieveItems(item, 1, 0)
if err != nil {
return nil, err
}
return items[0], nil
}
// RetrieveItems returns multiple items in sequence, starting from the index 'start'.
// It will return at most 'max' items, but will abort earlier to respect the
// 'maxBytes' argument. However, if the 'maxBytes' is smaller than the size of one
// item, it _will_ return one element and possibly overflow the maxBytes.
func (t *freezerTable) RetrieveItems(start, count, maxBytes uint64) ([][]byte, error) {
// First we read the 'raw' data, which might be compressed.
diskData, sizes, err := t.retrieveItems(start, count, maxBytes)
if err != nil {
return nil, err
}
var (
output = make([][]byte, 0, count)
offset int // offset for reading
outputSize int // size of uncompressed data
)
// Now slice up the data and decompress.
for i, diskSize := range sizes {
item := diskData[offset : offset+diskSize]
offset += diskSize
decompressedSize := diskSize
if !t.noCompression {
decompressedSize, _ = snappy.DecodedLen(item)
}
if i > 0 && uint64(outputSize+decompressedSize) > maxBytes {
break
}
if !t.noCompression {
data, err := snappy.Decode(nil, item)
if err != nil {
return nil, err
}
output = append(output, data)
} else {
output = append(output, item)
}
outputSize += decompressedSize
}
return output, nil
}
// retrieveItems reads up to 'count' items from the table. It reads at least
// one item, but otherwise avoids reading more than maxBytes bytes.
// It returns the (potentially compressed) data, and the sizes.
func (t *freezerTable) retrieveItems(start, count, maxBytes uint64) ([]byte, []int, error) {
t.lock.RLock()
defer t.lock.RUnlock()
// Ensure the table and the item are accessible
if t.index == nil || t.head == nil {
return nil, nil, errClosed
}
var (
items = atomic.LoadUint64(&t.items) // the total items(head + 1)
hidden = atomic.LoadUint64(&t.itemHidden) // the number of hidden items
)
// Ensure the start is written, not deleted from the tail, and that the
// caller actually wants something
if items <= start || hidden > start || count == 0 {
return nil, nil, errOutOfBounds
}
if start+count > items {
count = items - start
}
var (
output = make([]byte, maxBytes) // Buffer to read data into
outputSize int // Used size of that buffer
)
// readData is a helper method to read a single data item from disk.
readData := func(fileId, start uint32, length int) error {
// In case a small limit is used, and the elements are large, may need to
// realloc the read-buffer when reading the first (and only) item.
if len(output) < length {
output = make([]byte, length)
}
dataFile, exist := t.files[fileId]
if !exist {
return fmt.Errorf("missing data file %d", fileId)
}
if _, err := dataFile.ReadAt(output[outputSize:outputSize+length], int64(start)); err != nil {
return err
}
outputSize += length
return nil
}
// Read all the indexes in one go
indices, err := t.getIndices(start, count)
if err != nil {
return nil, nil, err
}
var (
sizes []int // The sizes for each element
totalSize = 0 // The total size of all data read so far
readStart = indices[0].offset // Where, in the file, to start reading
unreadSize = 0 // The size of the as-yet-unread data
)
for i, firstIndex := range indices[:len(indices)-1] {
secondIndex := indices[i+1]
// Determine the size of the item.
offset1, offset2, _ := firstIndex.bounds(secondIndex)
size := int(offset2 - offset1)
// Crossing a file boundary?
if secondIndex.filenum != firstIndex.filenum {
// If we have unread data in the first file, we need to do that read now.
if unreadSize > 0 {
if err := readData(firstIndex.filenum, readStart, unreadSize); err != nil {
return nil, nil, err
}
unreadSize = 0
}
readStart = 0
}
if i > 0 && uint64(totalSize+size) > maxBytes {
// About to break out due to byte limit being exceeded. We don't
// read this last item, but we need to do the deferred reads now.
if unreadSize > 0 {
if err := readData(secondIndex.filenum, readStart, unreadSize); err != nil {
return nil, nil, err
}
}
break
}
// Defer the read for later
unreadSize += size
totalSize += size
sizes = append(sizes, size)
if i == len(indices)-2 || uint64(totalSize) > maxBytes {
// Last item, need to do the read now
if err := readData(secondIndex.filenum, readStart, unreadSize); err != nil {
return nil, nil, err
}
break
}
}
return output[:outputSize], sizes, nil
}
// has returns an indicator whether the specified number data is still accessible
// in the freezer table.
func (t *freezerTable) has(number uint64) bool {
return atomic.LoadUint64(&t.items) > number && atomic.LoadUint64(&t.itemHidden) <= number
}
// size returns the total data size in the freezer table.
func (t *freezerTable) size() (uint64, error) {
t.lock.RLock()
defer t.lock.RUnlock()
return t.sizeNolock()
}
// sizeNolock returns the total data size in the freezer table without obtaining
// the mutex first.
func (t *freezerTable) sizeNolock() (uint64, error) {
stat, err := t.index.Stat()
if err != nil {
return 0, err
}
total := uint64(t.maxFileSize)*uint64(t.headId-t.tailId) + uint64(t.headBytes) + uint64(stat.Size())
return total, nil
}
// advanceHead should be called when the current head file would outgrow the file limits,
// and a new file must be opened. The caller of this method must hold the write-lock
// before calling this method.
func (t *freezerTable) advanceHead() error {
t.lock.Lock()
defer t.lock.Unlock()
// We open the next file in truncated mode -- if this file already
// exists, we need to start over from scratch on it.
nextID := t.headId + 1
newHead, err := t.openFile(nextID, openFreezerFileTruncated)
if err != nil {
return err
}
// Close old file, and reopen in RDONLY mode.
t.releaseFile(t.headId)
t.openFile(t.headId, openFreezerFileForReadOnly)
// Swap out the current head.
t.head = newHead
t.headBytes = 0
t.headId = nextID
return nil
}
// Sync pushes any pending data from memory out to disk. This is an expensive
// operation, so use it with care.
func (t *freezerTable) Sync() error {
t.lock.Lock()
defer t.lock.Unlock()
var err error
trackError := func(e error) {
if e != nil && err == nil {
err = e
}
}
trackError(t.index.Sync())
trackError(t.meta.Sync())
trackError(t.head.Sync())
return err
}
func (t *freezerTable) dumpIndexStdout(start, stop int64) {
t.dumpIndex(os.Stdout, start, stop)
}
func (t *freezerTable) dumpIndexString(start, stop int64) string {
var out bytes.Buffer
out.WriteString("\n")
t.dumpIndex(&out, start, stop)
return out.String()
}
func (t *freezerTable) dumpIndex(w io.Writer, start, stop int64) {
meta, err := readMetadata(t.meta)
if err != nil {
fmt.Fprintf(w, "Failed to decode freezer table %v\n", err)
return
}
fmt.Fprintf(w, "Version %d deleted %d, hidden %d\n", meta.Version, atomic.LoadUint64(&t.itemOffset), atomic.LoadUint64(&t.itemHidden))
buf := make([]byte, indexEntrySize)
fmt.Fprintf(w, "| number | fileno | offset |\n")
fmt.Fprintf(w, "|--------|--------|--------|\n")
for i := uint64(start); ; i++ {
if _, err := t.index.ReadAt(buf, int64((i+1)*indexEntrySize)); err != nil {
break
}
var entry indexEntry
entry.unmarshalBinary(buf)
fmt.Fprintf(w, "| %03d | %03d | %03d | \n", i, entry.filenum, entry.offset)
if stop > 0 && i >= uint64(stop) {
break
}
}
fmt.Fprintf(w, "|--------------------------|\n")
}