seaweedfs/weed/filer/reader_at.go
2022-02-26 03:06:17 -08:00

179 lines
5.4 KiB
Go

package filer
import (
"context"
"fmt"
"io"
"math/rand"
"sync"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
"github.com/chrislusf/seaweedfs/weed/util"
"github.com/chrislusf/seaweedfs/weed/util/chunk_cache"
"github.com/chrislusf/seaweedfs/weed/wdclient"
)
type ChunkReadAt struct {
masterClient *wdclient.MasterClient
chunkViews []*ChunkView
readerLock sync.Mutex
fileSize int64
readerCache *ReaderCache
readerPattern *ReaderPattern
}
var _ = io.ReaderAt(&ChunkReadAt{})
var _ = io.Closer(&ChunkReadAt{})
func LookupFn(filerClient filer_pb.FilerClient) wdclient.LookupFileIdFunctionType {
vidCache := make(map[string]*filer_pb.Locations)
var vicCacheLock sync.RWMutex
return func(fileId string) (targetUrls []string, err error) {
vid := VolumeId(fileId)
vicCacheLock.RLock()
locations, found := vidCache[vid]
vicCacheLock.RUnlock()
if !found {
util.Retry("lookup volume "+vid, func() error {
err = filerClient.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
resp, err := client.LookupVolume(context.Background(), &filer_pb.LookupVolumeRequest{
VolumeIds: []string{vid},
})
if err != nil {
return err
}
locations = resp.LocationsMap[vid]
if locations == nil || len(locations.Locations) == 0 {
glog.V(0).Infof("failed to locate %s", fileId)
return fmt.Errorf("failed to locate %s", fileId)
}
vicCacheLock.Lock()
vidCache[vid] = locations
vicCacheLock.Unlock()
return nil
})
return err
})
}
if err != nil {
return nil, err
}
for _, loc := range locations.Locations {
volumeServerAddress := filerClient.AdjustedUrl(loc)
targetUrl := fmt.Sprintf("http://%s/%s", volumeServerAddress, fileId)
targetUrls = append(targetUrls, targetUrl)
}
for i := len(targetUrls) - 1; i > 0; i-- {
j := rand.Intn(i + 1)
targetUrls[i], targetUrls[j] = targetUrls[j], targetUrls[i]
}
return
}
}
func NewChunkReaderAtFromClient(lookupFn wdclient.LookupFileIdFunctionType, chunkViews []*ChunkView, chunkCache chunk_cache.ChunkCache, fileSize int64) *ChunkReadAt {
return &ChunkReadAt{
chunkViews: chunkViews,
fileSize: fileSize,
readerCache: newReaderCache(5, chunkCache, lookupFn),
readerPattern: NewReaderPattern(),
}
}
func (c *ChunkReadAt) Close() error {
c.readerCache.destroy()
return nil
}
func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) {
c.readerPattern.MonitorReadAt(offset, len(p))
c.readerLock.Lock()
defer c.readerLock.Unlock()
// glog.V(4).Infof("ReadAt [%d,%d) of total file size %d bytes %d chunk views", offset, offset+int64(len(p)), c.fileSize, len(c.chunkViews))
return c.doReadAt(p, offset)
}
func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
startOffset, remaining := offset, int64(len(p))
var nextChunks []*ChunkView
for i, chunk := range c.chunkViews {
if remaining <= 0 {
break
}
if i+1 < len(c.chunkViews) {
nextChunks = c.chunkViews[i+1:]
}
if startOffset < chunk.LogicOffset {
gap := int(chunk.LogicOffset - startOffset)
glog.V(4).Infof("zero [%d,%d)", startOffset, chunk.LogicOffset)
n += int(min(int64(gap), remaining))
startOffset, remaining = chunk.LogicOffset, remaining-int64(gap)
if remaining <= 0 {
break
}
}
// fmt.Printf(">>> doReadAt [%d,%d), chunk[%d,%d)\n", offset, offset+int64(len(p)), chunk.LogicOffset, chunk.LogicOffset+int64(chunk.Size))
chunkStart, chunkStop := max(chunk.LogicOffset, startOffset), min(chunk.LogicOffset+int64(chunk.Size), startOffset+remaining)
if chunkStart >= chunkStop {
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))
bufferOffset := chunkStart - chunk.LogicOffset + chunk.Offset
copied, err := c.readChunkSliceAt(p[startOffset-offset:chunkStop-chunkStart+startOffset-offset], chunk, nextChunks, uint64(bufferOffset))
if err != nil {
glog.Errorf("fetching chunk %+v: %v\n", chunk, err)
return copied, err
}
n += copied
startOffset, remaining = startOffset+int64(copied), remaining-int64(copied)
}
// glog.V(4).Infof("doReadAt [%d,%d), n:%v, err:%v", offset, offset+int64(len(p)), n, err)
if err == nil && remaining > 0 && c.fileSize > startOffset {
delta := int(min(remaining, c.fileSize-startOffset))
glog.V(4).Infof("zero2 [%d,%d) of file size %d bytes", startOffset, startOffset+int64(delta), c.fileSize)
n += delta
}
if err == nil && offset+int64(len(p)) >= c.fileSize {
err = io.EOF
}
// fmt.Printf("~~~ filled %d, err: %v\n\n", n, err)
return
}
func (c *ChunkReadAt) readChunkSliceAt(buffer []byte, chunkView *ChunkView, nextChunkViews []*ChunkView, offset uint64) (n int, err error) {
if c.readerPattern.IsRandomMode() {
return c.readerCache.ReadChunkAt(buffer, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(chunkView.ChunkSize), chunkView.LogicOffset == 0)
}
n, err = c.readerCache.ReadChunkAt(buffer, chunkView.FileId, chunkView.CipherKey, chunkView.IsGzipped, int64(offset), int(chunkView.ChunkSize), chunkView.LogicOffset == 0)
for i, nextChunk := range nextChunkViews {
if i < 2 {
c.readerCache.MaybeCache(nextChunk.FileId, nextChunk.CipherKey, nextChunk.IsGzipped, int(nextChunk.ChunkSize))
} else {
break
}
}
return
}