start using chunk cache

3 files changed, 33 insertions, 54 deletions

diff --git a/TODO.md b/TODO.md
index 72301cf..b35bff4 100644
--- a/TODO.md
+++ b/TODO.md
@@ -23,15 +23,7 @@ priority 1
         - [ ] compress before storing
         - [ ] uncompress before loading
     - [ ] store compressed chunks into tracks of trackSize (1024o)
-- [ ] add chunk cache that would look like this:
-    ```go
-    type ChunkCache map[ChunkId][]byte // Do we really want to only keep the chunk content ?
-
-    type Cache interface {
-        Get(id ChunkId) Chunk
-        Set(id ChunkId, Chunk)
-    }
-    ```
+- [x] add chunk cache... what was it for again ??
 
 priority 2
 ----------
diff --git a/chunk.go b/chunk.go
index ba8334b..196152e 100644
--- a/chunk.go
+++ b/chunk.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -25,11 +24,6 @@ type BufferedChunk interface {
 	Bytes() []byte
 }
 
-type StorerChunk interface {
-	Chunk
-	Store(path string) error
-}
-
 type ChunkId struct {
 	Ver int
 	Idx uint64
@@ -39,15 +33,6 @@ func (i *ChunkId) Path(repo string) string {
 	return path.Join(repo, fmt.Sprintf(versionFmt, i.Ver), chunksName, fmt.Sprintf(chunkIdFmt, i.Idx))
 }
 
-func (i *ChunkId) Reader(repo *Repo) io.ReadSeeker {
-	path := i.Path(repo.path)
-	f, err := os.Open(path)
-	if err != nil {
-		log.Println("Cannot open chunk: ", path)
-	}
-	return f
-}
-
 func NewLoadedChunk(id *ChunkId, value []byte) *LoadedChunk {
 	return &LoadedChunk{Id: id, value: value}
 }
@@ -74,10 +59,6 @@ func (c *LoadedChunk) Bytes() []byte {
 	return c.value
 }
 
-func (c *LoadedChunk) Store(path string) error {
-	return storeChunk(c.Reader(), c.Id.Path(path))
-}
-
 func NewStoredChunk(repo *Repo, id *ChunkId) *StoredChunk {
 	return &StoredChunk{repo: repo, Id: id}
 }
@@ -93,7 +74,7 @@ func (c *StoredChunk) GetId() *ChunkId {
 
 func (c *StoredChunk) Reader() io.ReadSeeker {
 	// log.Printf("Chunk %d: Reading from file\n", c.id)
-	return c.Id.Reader(c.repo)
+	return c.repo.LoadChunkContent(c.Id)
 }
 
 func (c *StoredChunk) Len() int {
@@ -142,7 +123,7 @@ type DeltaChunk struct {
 
 func (c *DeltaChunk) Reader() io.ReadSeeker {
 	var buff bytes.Buffer
-	c.repo.Patcher().Patch(c.Source.Reader(c.repo), &buff, bytes.NewReader(c.Patch))
+	c.repo.Patcher().Patch(c.repo.LoadChunkContent(c.Source), &buff, bytes.NewReader(c.Patch))
 	return bytes.NewReader(buff.Bytes())
 }
 
@@ -150,18 +131,3 @@ func (c *DeltaChunk) Reader() io.ReadSeeker {
 func (c *DeltaChunk) Len() int {
 	return c.Size
 }
-
-func storeChunk(r io.Reader, path string) error {
-	file, err := os.Create(path)
-	if err != nil {
-		return errors.New(fmt.Sprintf("Error creating chunk for '%s'; %s\n", path, err))
-	}
-	n, err := io.Copy(file, r)
-	if err != nil {
-		return errors.New(fmt.Sprintf("Error writing chunk content for '%s', written %d bytes: %s\n", path, n, err))
-	}
-	if err := file.Close(); err != nil {
-		return errors.New(fmt.Sprintf("Error closing chunk for '%s': %s\n", path, err))
-	}
-	return nil
-}
diff --git a/repo.go b/repo.go
index 49ff088..2be457d 100644
--- a/repo.go
+++ b/repo.go
@@ -28,6 +28,7 @@ import (
 	"bufio"
 	"bytes"
 	"encoding/gob"
+	"errors"
 	"fmt"
 	"hash"
 	"io"
@@ -225,19 +226,39 @@ func loadFileList(path string) []File {
 	return files
 }
 
-// GetChunk loads a chunk from the repo.
+func (r *Repo) StoreChunkContent(id *ChunkId, reader io.Reader) error {
+	path := id.Path(r.path)
+	file, err := os.Create(path)
+	if err != nil {
+		return errors.New(fmt.Sprintf("Error creating chunk for '%s'; %s\n", path, err))
+	}
+	n, err := io.Copy(file, reader)
+	if err != nil {
+		return errors.New(fmt.Sprintf("Error writing chunk content for '%s', written %d bytes: %s\n", path, n, err))
+	}
+	if err := file.Close(); err != nil {
+		return errors.New(fmt.Sprintf("Error closing chunk for '%s': %s\n", path, err))
+	}
+	return nil
+}
+
+// LoadChunkContent loads a chunk from the repo.
 // If the chunk is in cache, get it from cache, else read it from drive.
-func (r *Repo) GetChunk(id *ChunkId) *LoadedChunk {
-	var err error
+func (r *Repo) LoadChunkContent(id *ChunkId) io.ReadSeeker {
 	value, exists := r.chunkCache.Get(id)
 	if !exists {
-		value, err = io.ReadAll(id.Reader(r))
+		path := id.Path(r.path)
+		f, err := os.Open(path)
+		if err != nil {
+			log.Printf("Cannot open chunk '%s': %s\n", path, err)
+		}
+		value, err = io.ReadAll(f)
 		if err != nil {
-			log.Panicf("Could not read from chunk %d: %s", id, err)
+			log.Panicf("Could not read from chunk '%s': %s\n", path, err)
 		}
 		r.chunkCache.Set(id, value)
 	}
-	return NewLoadedChunk(id, value)
+	return bytes.NewReader(value)
 }
 
 func storeChunks(dest string, chunks <-chan []byte) {
@@ -349,7 +370,7 @@ func (r *Repo) tryDeltaEncodeChunk(temp BufferedChunk) (Chunk, bool) {
 	id, found := r.findSimilarChunk(temp)
 	if found {
 		var buff bytes.Buffer
-		if err := r.differ.Diff(id.Reader(r), temp.Reader(), &buff); err != nil {
+		if err := r.differ.Diff(r.LoadChunkContent(id), temp.Reader(), &buff); err != nil {
 			log.Println("Error trying delta encode chunk:", temp, "with source:", id, ":", err)
 		} else {
 			return &DeltaChunk{
@@ -377,9 +398,9 @@ func (r *Repo) encodeTempChunk(temp BufferedChunk, version int, last *uint64) (c
 		ic := NewLoadedChunk(id, temp.Bytes())
 		hasher := rabinkarp64.NewFromPol(r.pol)
 		r.hashAndStoreChunk(ic, hasher)
-		ic.Store(r.path)
+		r.StoreChunkContent(id, ic.Reader())
 		log.Println("Add new chunk", id)
-		return ic, false
+		return NewStoredChunk(r, id), false
 	}
 	log.Println("Add new partial chunk of size:", chunk.Len())
 	return