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localComm.go
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/
localComm.go
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// Copyright 2015 Netflix, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package chunked
import (
"bufio"
"io"
"github.com/hongst/rend/binprot"
"github.com/hongst/rend/common"
"github.com/hongst/rend/metrics"
)
// TODO: replace sending new empty metadata on miss with emptyMeta
var emptyMeta = metadata{}
func getAndTouchMetadata(rw *bufio.ReadWriter, key []byte, exptime uint32) ([]byte, metadata, error) {
metaKey := metaKey(key)
if err := binprot.WriteGATCmd(rw, metaKey, exptime); err != nil {
return nil, emptyMeta, err
}
metaData, err := getMetadataCommon(rw)
return metaKey, metaData, err
}
func getMetadata(rw *bufio.ReadWriter, key []byte) ([]byte, metadata, error) {
metaKey := metaKey(key)
if err := binprot.WriteGetCmd(rw, metaKey); err != nil {
return nil, emptyMeta, err
}
metaData, err := getMetadataCommon(rw)
return metaKey, metaData, err
}
func getMetadataCommon(rw *bufio.ReadWriter) (metadata, error) {
if err := rw.Flush(); err != nil {
return emptyMeta, err
}
resHeader, err := binprot.ReadResponseHeader(rw)
if err != nil {
return emptyMeta, err
}
defer binprot.PutResponseHeader(resHeader)
err = binprot.DecodeError(resHeader)
if err != nil {
// read in the message "Not found" after a miss
n, ioerr := rw.Discard(int(resHeader.TotalBodyLength))
metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
if ioerr != nil {
return emptyMeta, ioerr
}
return emptyMeta, err
}
// we currently do nothing with the flags
//buf := make([]byte, 4)
//n, err := io.ReadAtLeast(rw, buf, 4)
//metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
//if err != nil {
// return emptyMeta, err
//}
//serverFlags := binary.BigEndian.Uint32(buf)
// instead of reading and parsing flags, just discard
rw.Discard(4)
metrics.IncCounterBy(common.MetricBytesReadLocal, 4)
metaData, err := readMetadata(rw)
if err != nil {
return emptyMeta, err
}
return metaData, nil
}
func simpleCmdLocal(rw *bufio.ReadWriter, flush bool) error {
if flush {
if err := rw.Flush(); err != nil {
return err
}
}
resHeader, err := binprot.ReadResponseHeader(rw)
if err != nil {
return err
}
n, ioerr := rw.Discard(int(resHeader.TotalBodyLength))
metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
if ioerr != nil {
binprot.PutResponseHeader(resHeader)
return ioerr
}
binprot.PutResponseHeader(resHeader)
return binprot.DecodeError(resHeader)
}
func getLocalIntoBuf(rw *bufio.Reader, metaData metadata, tokenBuf, dataBuf []byte, chunkNum, totalDataLength int) (opcodeNoop bool, err error) {
resHeader, err := binprot.ReadResponseHeader(rw)
if err != nil {
return false, err
}
defer binprot.PutResponseHeader(resHeader)
// it feels a bit dirty knowing about batch gets here, but it's the most logical place to put
// a check for an opcode that signals the end of a batch get or GAT. This code is a bit too big
// to copy-paste in multiple places.
if resHeader.Opcode == binprot.OpcodeNoop {
return true, nil
}
err = binprot.DecodeError(resHeader)
if err != nil {
// read in the message "Not found" after a miss
n, ioerr := rw.Discard(int(resHeader.TotalBodyLength))
metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
if ioerr != nil {
return false, ioerr
}
return false, err
}
// we currently do nothing with the flags
//buf := make([]byte, 4)
//n, err := io.ReadAtLeast(rw, buf, 4)
//metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
//if err != nil {
// return emptyMeta, err
//}
//serverFlags := binary.BigEndian.Uint32(buf)
// instead of reading and parsing flags, just discard
rw.Discard(4)
metrics.IncCounterBy(common.MetricBytesReadLocal, 4)
// Read in token if requested
if tokenBuf != nil {
n, err := io.ReadAtLeast(rw, tokenBuf, tokenSize)
metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
if err != nil {
return false, err
}
}
// indices for slicing, end exclusive
start, end := chunkSliceIndices(int(metaData.ChunkSize), chunkNum, int(metaData.Length))
// read data directly into buf
chunkBuf := dataBuf[start:end]
// Read in value
n, err := io.ReadAtLeast(rw, chunkBuf, len(chunkBuf))
metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
if err != nil {
return false, err
}
// consume padding at end of chunk if needed
if len(chunkBuf) < totalDataLength {
n, ioerr := rw.Discard(totalDataLength - len(chunkBuf))
metrics.IncCounterBy(common.MetricBytesReadLocal, uint64(n))
if ioerr != nil {
return false, ioerr
}
}
return false, nil
}