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core/rawdb: avoid O_APPEND #19676

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Merged
merged 3 commits into from
Jun 10, 2019
Merged

core/rawdb: avoid O_APPEND #19676

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e7feb2f
Fix file system access for Windows
FrankSzendzielarz Jun 6, 2019
fb66068
Encapsulate file accesses
FrankSzendzielarz Jun 7, 2019
5d7e17f
Style fixes
FrankSzendzielarz Jun 9, 2019
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76 changes: 57 additions & 19 deletions core/rawdb/freezer_table.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@ import (
"encoding/binary"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"sync"
Expand Down Expand Up @@ -106,6 +107,44 @@ func newTable(path string, name string, readMeter metrics.Meter, writeMeter metr
return newCustomTable(path, name, readMeter, writeMeter, 2*1000*1000*1000, disableSnappy)
}

// openFreezerFile opens a freezer table file and seeks to the end
func openFreezerFileForAppend(filename string) (*os.File, error) {
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@karalabe karalabe Jun 7, 2019

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Nitpick, please fix the comments so they reference the correct method (on this and the 2 methods below).

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@karalabe karalabe Jun 7, 2019

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And in general, please leave an empty space after the // characters within the method comments.

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@karalabe karalabe Jun 7, 2019

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And please capitalize min-method comments :)

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@FrankSzendzielarz FrankSzendzielarz Jun 9, 2019

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lol, well spotted. thanks, and done :-)

//open the file without the O_APPEND flag
//because it has differing behaviour during Truncate operations
//on different OS's
file, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE, 0644)
if err != nil {
return nil, err
}
//seek to end for append
if _, err = file.Seek(0, io.SeekEnd); err != nil {
return nil, err
}
return file, nil
}

// openFreezerFile opens a freezer table file for read only access
func openFreezerFileForReadOnly(filename string) (*os.File, error) {
return os.OpenFile(filename, os.O_RDONLY, 0644)
}

// openFreezerFile opens a freezer table making sure it is truncated
func openFreezerFileTruncated(filename string) (*os.File, error) {
return os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
}

// truncateFreezerFile resizes a freezer table file and seeks to the end
func truncateFreezerFile(file *os.File, size int64) error {
if err := file.Truncate(size); err != nil {
return err
}
//seek to end for append
if _, err := file.Seek(0, io.SeekEnd); err != nil {
return err
}
return nil
}

// newCustomTable 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.
Expand All @@ -122,7 +161,7 @@ func newCustomTable(path string, name string, readMeter metrics.Meter, writeMete
// compressed idx
idxName = fmt.Sprintf("%s.cidx", name)
}
offsets, err := os.OpenFile(filepath.Join(path, idxName), os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)
offsets, err := openFreezerFileForAppend(filepath.Join(path, idxName))
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -163,7 +202,7 @@ func (t *freezerTable) repair() error {
}
// Ensure the index is a multiple of indexEntrySize bytes
if overflow := stat.Size() % indexEntrySize; overflow != 0 {
t.index.Truncate(stat.Size() - overflow) // New file can't trigger this path
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 {
Expand All @@ -188,7 +227,7 @@ func (t *freezerTable) repair() error {

t.index.ReadAt(buffer, offsetsSize-indexEntrySize)
lastIndex.unmarshalBinary(buffer)
t.head, err = t.openFile(lastIndex.filenum, os.O_RDWR|os.O_CREATE|os.O_APPEND)
t.head, err = t.openFile(lastIndex.filenum, openFreezerFileForAppend)
if err != nil {
return err
}
Expand All @@ -204,15 +243,15 @@ func (t *freezerTable) repair() error {
// 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 := t.head.Truncate(contentExp); err != nil {
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 := t.index.Truncate(offsetsSize - indexEntrySize); err != nil {
if err := truncateFreezerFile(t.index, offsetsSize-indexEntrySize); err != nil {
return err
}
offsetsSize -= indexEntrySize
Expand All @@ -223,7 +262,7 @@ func (t *freezerTable) repair() error {
if newLastIndex.filenum != lastIndex.filenum {
// release earlier opened file
t.releaseFile(lastIndex.filenum)
t.head, err = t.openFile(newLastIndex.filenum, os.O_RDWR|os.O_CREATE|os.O_APPEND)
t.head, err = t.openFile(newLastIndex.filenum, openFreezerFileForAppend)
if stat, err = t.head.Stat(); err != nil {
// TODO, anything more we can do here?
// A data file has gone missing...
Expand Down Expand Up @@ -264,16 +303,16 @@ func (t *freezerTable) preopen() (err error) {
t.releaseFilesAfter(0, false)
// Open all except head in RDONLY
for i := t.tailId; i < t.headId; i++ {
if _, err = t.openFile(i, os.O_RDONLY); err != nil {
if _, err = t.openFile(i, openFreezerFileForReadOnly); err != nil {
return err
}
}
// Open head in read/write
t.head, err = t.openFile(t.headId, os.O_RDWR|os.O_CREATE|os.O_APPEND)
t.head, err = t.openFile(t.headId, openFreezerFileForAppend)
return err
}

// truncate discards any recent data above the provided threashold number.
// truncate discards any recent data above the provided threshold number.
func (t *freezerTable) truncate(items uint64) error {
t.lock.Lock()
defer t.lock.Unlock()
Expand All @@ -284,7 +323,7 @@ func (t *freezerTable) truncate(items uint64) error {
}
// Something's out of sync, truncate the table's offset index
t.logger.Warn("Truncating freezer table", "items", t.items, "limit", items)
if err := t.index.Truncate(int64(items+1) * indexEntrySize); err != nil {
if err := truncateFreezerFile(t.index, int64(items+1)*indexEntrySize); err != nil {
return err
}
// Calculate the new expected size of the data file and truncate it
Expand All @@ -299,7 +338,7 @@ func (t *freezerTable) truncate(items uint64) error {
if expected.filenum != t.headId {
// If already open for reading, force-reopen for writing
t.releaseFile(expected.filenum)
newHead, err := t.openFile(expected.filenum, os.O_RDWR|os.O_CREATE|os.O_APPEND)
newHead, err := t.openFile(expected.filenum, openFreezerFileForAppend)
if err != nil {
return err
}
Expand All @@ -310,7 +349,7 @@ func (t *freezerTable) truncate(items uint64) error {
t.head = newHead
atomic.StoreUint32(&t.headId, expected.filenum)
}
if err := t.head.Truncate(int64(expected.offset)); err != nil {
if err := truncateFreezerFile(t.head, int64(expected.offset)); err != nil {
return err
}
// All data files truncated, set internal counters and return
Expand Down Expand Up @@ -344,7 +383,7 @@ func (t *freezerTable) Close() error {
}

// openFile assumes that the write-lock is held by the caller
func (t *freezerTable) openFile(num uint32, flag int) (f *os.File, err error) {
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
Expand All @@ -353,7 +392,7 @@ func (t *freezerTable) openFile(num uint32, flag int) (f *os.File, err error) {
} else {
name = fmt.Sprintf("%s.%04d.cdat", t.name, num)
}
f, err = os.OpenFile(filepath.Join(t.path, name), flag, 0644)
f, err = opener(filepath.Join(t.path, name))
if err != nil {
return nil, err
}
Expand Down Expand Up @@ -413,28 +452,27 @@ func (t *freezerTable) Append(item uint64, blob []byte) error {
// we need a new file, writing would overflow
t.lock.RUnlock()
t.lock.Lock()
nextId := atomic.LoadUint32(&t.headId) + 1
nextID := atomic.LoadUint32(&t.headId) + 1
// We open the next file in truncated mode -- if this file already
// exists, we need to start over from scratch on it
newHead, err := t.openFile(nextId, os.O_RDWR|os.O_CREATE|os.O_TRUNC)
newHead, err := t.openFile(nextID, openFreezerFileTruncated)
if err != nil {
t.lock.Unlock()
return err
}
// Close old file, and reopen in RDONLY mode
t.releaseFile(t.headId)
t.openFile(t.headId, os.O_RDONLY)
t.openFile(t.headId, openFreezerFileForReadOnly)

// Swap out the current head
t.head = newHead
atomic.StoreUint32(&t.headBytes, 0)
atomic.StoreUint32(&t.headId, nextId)
atomic.StoreUint32(&t.headId, nextID)
t.lock.Unlock()
t.lock.RLock()
}

defer t.lock.RUnlock()

if _, err := t.head.Write(blob); err != nil {
return err
}
Expand Down