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mount: read prefetching

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This commit is contained in:
Chris Lu 2020-10-04 01:31:04 -07:00
parent bc47835997
commit 666859f7cd
3 changed files with 58 additions and 21 deletions
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1
go.mod
View File

@ -78,6 +78,7 @@ require (
gocloud.dev/pubsub/rabbitpubsub v0.16.0
golang.org/x/image v0.0.0-20200119044424-58c23975cae1 // indirect
golang.org/x/net v0.0.0-20200202094626-16171245cfb2
golang.org/x/sync v0.0.0-20200930132711-30421366ff76 // indirect
golang.org/x/sys v0.0.0-20200202164722-d101bd2416d5
golang.org/x/tools v0.0.0-20191029190741-b9c20aec41a5
google.golang.org/api v0.9.0

2
go.sum
View File

@ -615,6 +615,8 @@ golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJ
golang.org/x/sync v0.0.0-20190412183630-56d357773e84/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20190423024810-112230192c58 h1:8gQV6CLnAEikrhgkHFbMAEhagSSnXWGV915qUMm9mrU=
golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sync v0.0.0-20200930132711-30421366ff76 h1:JnxiSYT3Nm0BT2a8CyvYyM6cnrWpidecD1UuSYbhKm0=
golang.org/x/sync v0.0.0-20200930132711-30421366ff76/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
golang.org/x/sys v0.0.0-20180909124046-d0be0721c37e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

76
weed/filer/reader_at.go
View File

@ -3,6 +3,7 @@ package filer
import (
"context"
"fmt"
"github.com/golang/groupcache/singleflight"
"io"
"math/rand"
"sync"
@ -18,12 +19,12 @@ type ChunkReadAt struct {
chunkViews []*ChunkView
lookupFileId func(fileId string) (targetUrl string, err error)
readerLock sync.Mutex
fetcherLock sync.Mutex
fileSize int64
lastChunkFileId string
lastChunkData []byte
chunkCache chunk_cache.ChunkCache
fetchGroup singleflight.Group
lastChunkFileId string
lastChunkData []byte
chunkCache chunk_cache.ChunkCache
}
// var _ = io.ReaderAt(&ChunkReadAt{})
@ -88,10 +89,16 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
var buffer []byte
startOffset, remaining := offset, int64(len(p))
var nextChunk *ChunkView
for i, chunk := range c.chunkViews {
if remaining <= 0 {
break
}
if i+1 < len(c.chunkViews) {
nextChunk = c.chunkViews[i+1]
} else {
nextChunk = nil
}
if startOffset < chunk.LogicOffset {
gap := int(chunk.LogicOffset - startOffset)
glog.V(4).Infof("zero [%d,%d)", startOffset, startOffset+int64(gap))
@ -107,7 +114,7 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
continue
}
glog.V(4).Infof("read [%d,%d), %d/%d chunk %s [%d,%d)", chunkStart, chunkStop, i, len(c.chunkViews), chunk.FileId, chunk.LogicOffset-chunk.Offset, chunk.LogicOffset-chunk.Offset+int64(chunk.Size))
buffer, err = c.readFromWholeChunkData(chunk)
buffer, err = c.readFromWholeChunkData(chunk, nextChunk)
if err != nil {
glog.Errorf("fetching chunk %+v: %v\n", chunk, err)
return
@ -135,36 +142,63 @@ func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
}
func (c *ChunkReadAt) readFromWholeChunkData(chunkView *ChunkView) (chunkData []byte, err error) {
c.fetcherLock.Lock()
defer c.fetcherLock.Unlock()
func (c *ChunkReadAt) readFromWholeChunkData(chunkView, nextChunkView *ChunkView) (chunkData []byte, err error) {
if c.lastChunkFileId == chunkView.FileId {
return c.lastChunkData, nil
}
glog.V(4).Infof("readFromWholeChunkData %s offset %d [%d,%d) size at least %d", chunkView.FileId, chunkView.Offset, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size), chunkView.ChunkSize)
v, doErr := c.readOneWholeChunk(chunkView)
chunkData = c.chunkCache.GetChunk(chunkView.FileId, chunkView.ChunkSize)
if chunkData != nil {
glog.V(4).Infof("cache hit %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset-chunkView.Offset, chunkView.LogicOffset-chunkView.Offset+int64(len(chunkData)))
} else {
chunkData, err = c.doFetchFullChunkData(chunkView)
if err != nil {
return
}
c.chunkCache.SetChunk(chunkView.FileId, chunkData)
c.lastChunkData = chunkData
c.lastChunkFileId = chunkView.FileId
if doErr != nil {
return
}
chunkData = v.([]byte)
c.lastChunkData = chunkData
c.lastChunkFileId = chunkView.FileId
go func() {
if c.chunkCache != nil && nextChunkView != nil {
c.readOneWholeChunk(nextChunkView)
}
}()
return
}
func (c *ChunkReadAt) readOneWholeChunk(chunkView *ChunkView) (interface{}, error) {
var err error
return c.fetchGroup.Do(chunkView.FileId, func() (interface{}, error) {
glog.V(4).Infof("readFromWholeChunkData %s offset %d [%d,%d) size at least %d", chunkView.FileId, chunkView.Offset, chunkView.LogicOffset, chunkView.LogicOffset+int64(chunkView.Size), chunkView.ChunkSize)
data := c.chunkCache.GetChunk(chunkView.FileId, chunkView.ChunkSize)
if data != nil {
glog.V(4).Infof("cache hit %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset-chunkView.Offset, chunkView.LogicOffset-chunkView.Offset+int64(len(data)))
} else {
var err error
data, err = c.doFetchFullChunkData(chunkView)
if err != nil {
return data, err
}
c.chunkCache.SetChunk(chunkView.FileId, data)
}
return data, err
})
}
func (c *ChunkReadAt) doFetchFullChunkData(chunkView *ChunkView) ([]byte, error) {
glog.V(2).Infof("+ doFetchFullChunkData %s", chunkView.FileId)
data, err := fetchChunk(c.lookupFileId, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped)
glog.V(2).Infof("- doFetchFullChunkData %s", chunkView.FileId)
return data, err
}