mirror of
https://github.com/dolthub/dolt.git
synced 2026-04-24 19:49:43 -05:00
Chris Masone
1316d19462
Add DataStore.Factory and ChunkStore.Factory so that client programs
that need to create multiple namespaced {Chunk,Data}Stores of the kind
indicated by command line flags have a convenient way to do so. The
details of how this is implemented are mostly contained in the various
ChunkStore.Factory implementations:
1) MemoryStore, TestStore - no change
2) LevelDBStore - the namespace is used as a subdirectory of the path
provided by the user
3) HTTPStore - the namespace is used as a path prefix for the endpoints
supported by DataStoreServer
4) DynamoStore - the namespace is used as a prefix on all keys
This change also required that DataStoreServer be able to handle URLs
of the form "http://server:port/namespace/endpoint", e.g.
"http://localhost:8000/mydatastore/getRefs". It currently still handles
the non-namespaced endpoints as well.
In order to make code from DataStoreServer more re-usable in other
contexts, the functions that handle calls to the server's various
endpoints are now standalone and live in datas/handlers.go.
DataStoreServer just contains logic for dispatch and server lifetime
management.
116 lines
2.3 KiB
Go
116 lines
2.3 KiB
Go
package chunks
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import (
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"bytes"
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"crypto/sha1"
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"encoding/binary"
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"io"
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"sync"
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"github.com/attic-labs/noms/d"
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"github.com/attic-labs/noms/ref"
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)
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/*
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Chunk Serialization:
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Chunk 0
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Chunk 1
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..
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Chunk N
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Chunk:
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Ref // 20-byte sha1 hash
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Len // 4-byte int
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Data // len(Data) == Len
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*/
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// NewSerializer creates a serializer which is a ChunkSink. Put() chunks will be serialized to |writer|. Close() must be called when no more chunks will be serialized.
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func NewSerializer(writer io.Writer) ChunkSink {
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s := &serializer{
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writer,
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make(chan Chunk, 64),
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make(chan struct{}),
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}
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go func() {
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for chunk := range s.chs {
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d.Chk.NotNil(chunk.Data)
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digest := chunk.Ref().Digest()
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n, err := io.Copy(s.writer, bytes.NewReader(digest[:]))
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d.Chk.NoError(err)
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d.Chk.Equal(int64(sha1.Size), n)
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// Because of chunking at higher levels, no chunk should never be more than 4GB
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chunkSize := uint32(len(chunk.Data()))
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err = binary.Write(s.writer, binary.LittleEndian, chunkSize)
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d.Chk.NoError(err)
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n, err = io.Copy(s.writer, bytes.NewReader(chunk.Data()))
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d.Chk.NoError(err)
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d.Chk.Equal(uint32(n), chunkSize)
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}
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s.done <- struct{}{}
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}()
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return s
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}
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type serializer struct {
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writer io.Writer
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chs chan Chunk
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done chan struct{}
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}
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func (sz *serializer) Put(c Chunk) {
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sz.chs <- c
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}
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func (sz *serializer) Close() error {
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close(sz.chs)
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<-sz.done
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return nil
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}
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// Deserialize reads off of |reader| until EOF, sending chunks to |cs|. If |rateLimit| is non-nill, concurrency will be limited to the available capacity of the channel.
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func Deserialize(reader io.Reader, cs ChunkSink, rateLimit chan struct{}) {
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wg := sync.WaitGroup{}
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for {
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digest := ref.Sha1Digest{}
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n, err := io.ReadFull(reader, digest[:])
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if err == io.EOF {
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break
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}
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d.Chk.NoError(err)
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d.Chk.Equal(int(sha1.Size), n)
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r := ref.New(digest)
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chunkSize := uint32(0)
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err = binary.Read(reader, binary.LittleEndian, &chunkSize)
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d.Chk.NoError(err)
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w := NewChunkWriter()
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n2, err := io.CopyN(w, reader, int64(chunkSize))
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d.Chk.NoError(err)
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d.Chk.Equal(int64(chunkSize), n2)
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c := w.Chunk()
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d.Chk.Equal(r, c.Ref())
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wg.Add(1)
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if rateLimit != nil {
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rateLimit <- struct{}{}
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}
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go func() {
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cs.Put(c)
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wg.Done()
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if rateLimit != nil {
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<-rateLimit
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}
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}()
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}
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wg.Wait()
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}
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