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streaming reads

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This commit is contained in:
Chris Lu 2020-08-16 21:07:46 -07:00
parent e72953dff7
commit 4ceeba9e70
1 changed files with 27 additions and 36 deletions
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63
weed/filer2/reader_at.go
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@ -80,48 +80,39 @@ func (c *ChunkReadAt) ReadAt(p []byte, offset int64) (n int, err error) {
func (c *ChunkReadAt) doReadAt(p []byte, offset int64) (n int, err error) {
var found bool
var chunkStart, chunkStop int64
var chunkView *ChunkView
var startOffset = offset
for _, chunk := range c.chunkViews {
// 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, offset), min(chunk.LogicOffset+int64(chunk.Size), offset+int64(len(p)))
chunkView = chunk
if chunkStart < chunkStop {
// fmt.Printf(">>> found [%d,%d), chunk %s [%d,%d)\n", chunkStart, chunkStop, chunk.FileId, chunk.LogicOffset, chunk.LogicOffset+int64(chunk.Size))
found = true
c.buffer, err = c.fetchWholeChunkData(chunk)
if err != nil {
glog.Errorf("fetching chunk %+v: %v\n", chunk, err)
}
c.bufferFileId = chunk.FileId
break
if startOffset < min(chunk.LogicOffset, int64(len(p))+offset) {
gap := int(min(chunk.LogicOffset, int64(len(p))+offset) - startOffset)
glog.V(4).Infof("zero [%d,%d)", n, n+gap)
n += gap
startOffset = chunk.LogicOffset
}
// 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, offset), min(chunk.LogicOffset+int64(chunk.Size), offset+int64(len(p)))
if chunkStart >= chunkStop {
continue
}
glog.V(4).Infof("read [%d,%d), chunk %s [%d,%d)\n", chunkStart, chunkStop, chunk.FileId, chunk.LogicOffset-chunk.Offset, chunk.LogicOffset-chunk.Offset+int64(chunk.Size))
c.buffer, err = c.fetchWholeChunkData(chunk)
if err != nil {
glog.Errorf("fetching chunk %+v: %v\n", chunk, err)
return
}
c.bufferFileId = chunk.FileId
bufferOffset := chunkStart - chunk.LogicOffset + chunk.Offset
copied := copy(p[chunkStart-offset:chunkStop-offset], c.buffer[bufferOffset:bufferOffset+chunkStop-chunkStart])
n += copied
startOffset += int64(copied)
}
// fmt.Printf("> doReadAt [%d,%d), buffer %s:%d, found:%v, err:%v\n", offset, offset+int64(len(p)), c.bufferFileId, int64(len(c.buffer)), found, err)
if err != nil {
return
if startOffset < min(c.fileSize, int64(len(p))+offset) {
gap := int(min(c.fileSize, int64(len(p))+offset) - startOffset)
glog.V(4).Infof("zero2 [%d,%d)", n, n+gap)
n += gap
}
if found {
bufferOffset := chunkStart - chunkView.LogicOffset + chunkView.Offset
/*
skipped, copied := chunkStart-offset, chunkStop-chunkStart
fmt.Printf("+++ copy %d+%d=%d fill:[%d, %d) p[%d,%d) <- buffer:[%d,%d) buffer %s:%d\nchunkView:%+v\n\n",
skipped, copied, skipped+copied,
chunkStart, chunkStop,
chunkStart-offset, chunkStop-offset, bufferOffset, bufferOffset+chunkStop-chunkStart,
c.bufferFileId, len(c.buffer),
chunkView)
*/
n = int(chunkStart-offset) +
copy(p[chunkStart-offset:chunkStop-offset], c.buffer[bufferOffset:bufferOffset+chunkStop-chunkStart])
return
}
n = len(p)
if offset+int64(n) >= c.fileSize {
err = io.EOF
}
@ -137,7 +128,7 @@ func (c *ChunkReadAt) fetchWholeChunkData(chunkView *ChunkView) (chunkData []byt
chunkData = c.chunkCache.GetChunk(chunkView.FileId, chunkView.ChunkSize)
if chunkData != nil {
glog.V(5).Infof("cache hit %s [%d,%d)", chunkView.FileId, chunkView.LogicOffset-chunkView.Offset, chunkView.LogicOffset-chunkView.Offset + int64(len(chunkData)))
glog.V(5).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.FileId, chunkView.CipherKey, chunkView.IsGzipped)
if err != nil {