Revert "Add initial support for multi pack indexes"

This reverts commit 6f8acbf1503d2fa1ef705d35a743fc6b279942e5.

Apparently my MIDX support is broken and it breaks some repos...
it'll be added back when ready.

3 files changed, 0 insertions, 336 deletions

diff --git a/pack_midx.go b/pack_midx.go
deleted file mode 100644
index 748bdaf6..00000000
--- a/pack_midx.go
+++ /dev/null
@@ -1,313 +0,0 @@
-package furgit
-
-import (
-	"fmt"
-	"os"
-	"path/filepath"
-	"strings"
-	"sync"
-	"syscall"
-)
-
-const (
-	midxMagic   = 0x4d494458 // MIDX
-	midxVersion = 1
-
-	midxOIDVersionSHA1   = 1
-	midxOIDVersionSHA256 = 2
-
-	chunkPNAM = 0x504e414d // PNAM
-	chunkOIDF = 0x4f494446 // OIDF
-	chunkOIDL = 0x4f49444c // OIDL
-	chunkOOFF = 0x4f4f4646 // OOFF
-	chunkLOFF = 0x4c4f4646 // LOFF
-)
-
-type multiPackIndex struct {
-	repo *Repository
-
-	loadOnce sync.Once
-	loadErr  error
-
-	numPacks   int
-	numObjects int
-	packNames  []string
-	fanout     []byte
-	oids       []byte
-	offsets    []byte
-	largeOffs  []byte
-	data       []byte
-
-	closeOnce sync.Once
-}
-
-func (midx *multiPackIndex) Close() error {
-	if midx == nil {
-		return nil
-	}
-	var closeErr error
-	midx.closeOnce.Do(func() {
-		if len(midx.data) > 0 {
-			if err := syscall.Munmap(midx.data); closeErr == nil {
-				closeErr = err
-			}
-			midx.data = nil
-			midx.fanout = nil
-			midx.oids = nil
-			midx.offsets = nil
-			midx.largeOffs = nil
-			midx.packNames = nil
-			midx.numObjects = 0
-			midx.numPacks = 0
-		}
-	})
-	return closeErr
-}
-
-func (midx *multiPackIndex) ensureLoaded() error {
-	midx.loadOnce.Do(func() {
-		midx.loadErr = midx.load()
-	})
-	return midx.loadErr
-}
-
-func (midx *multiPackIndex) load() error {
-	if midx.repo == nil {
-		return ErrInvalidObject
-	}
-	path := midx.repo.repoPath(filepath.Join("objects", "pack", "multi-pack-index"))
-	f, err := os.Open(path)
-	if err != nil {
-		return err
-	}
-	stat, err := f.Stat()
-	if err != nil {
-		_ = f.Close()
-		return err
-	}
-	if stat.Size() < 12 {
-		_ = f.Close()
-		return ErrInvalidObject
-	}
-	region, err := syscall.Mmap(
-		int(f.Fd()),
-		0,
-		int(stat.Size()),
-		syscall.PROT_READ,
-		syscall.MAP_PRIVATE,
-	)
-	if err != nil {
-		_ = f.Close()
-		return err
-	}
-	err = f.Close()
-	if err != nil {
-		_ = syscall.Munmap(region)
-		return err
-	}
-	err = midx.parse(region)
-	if err != nil {
-		_ = syscall.Munmap(region)
-		return err
-	}
-	midx.data = region
-	return nil
-}
-
-func (midx *multiPackIndex) parse(buf []byte) error {
-	if len(buf) < 12 {
-		return ErrInvalidObject
-	}
-
-	if readBE32(buf[0:4]) != midxMagic {
-		return ErrInvalidObject
-	}
-	if buf[4] != midxVersion {
-		return ErrInvalidObject
-	}
-	oidVersion := buf[5]
-	if oidVersion != midxOIDVersionSHA1 && oidVersion != midxOIDVersionSHA256 {
-		return ErrInvalidObject
-	}
-	numChunks := int(buf[6])
-	numBaseMIDX := int(buf[7])
-	if numBaseMIDX != 0 {
-		return ErrInvalidObject
-	}
-	numPacks := int(readBE32(buf[8:12]))
-
-	chunkTableStart := 12
-	chunkTableSize := (numChunks + 1) * 12
-	if len(buf) < chunkTableStart+chunkTableSize {
-		return ErrInvalidObject
-	}
-
-	chunks := make(map[uint32]int64)
-	for i := 0; i < numChunks; i++ {
-		chunkStart := chunkTableStart + i*12
-		chunkID := readBE32(buf[chunkStart : chunkStart+4])
-		chunkOffset := int64(readBE64(buf[chunkStart+4 : chunkStart+12]))
-		chunks[chunkID] = chunkOffset
-	}
-
-	pnamOffset, ok := chunks[chunkPNAM]
-	if !ok {
-		return ErrInvalidObject
-	}
-	if pnamOffset < 0 || pnamOffset >= int64(len(buf)) {
-		return ErrInvalidObject
-	}
-
-	nextOffset := int64(len(buf))
-	for _, offset := range chunks {
-		if offset > pnamOffset && offset < nextOffset {
-			nextOffset = offset
-		}
-	}
-
-	pnamData := buf[pnamOffset:nextOffset]
-	packNames := make([]string, 0, numPacks)
-	start := 0
-	for i := 0; i < numPacks; i++ {
-		end := start
-		for end < len(pnamData) && pnamData[end] != 0 {
-			end++
-		}
-		if end >= len(pnamData) {
-			return ErrInvalidObject
-		}
-		name := string(pnamData[start:end])
-		if strings.HasSuffix(name, ".idx") { // why...
-			name = name[:len(name)-4] + ".pack"
-		}
-		packNames = append(packNames, name)
-		start = end + 1
-	}
-
-	oidfOffset, ok := chunks[chunkOIDF]
-	if !ok {
-		return ErrInvalidObject
-	}
-	if oidfOffset < 0 || oidfOffset+256*4 > int64(len(buf)) {
-		return ErrInvalidObject
-	}
-	fanout := buf[oidfOffset : oidfOffset+256*4]
-	numObjects := int(readBE32(fanout[len(fanout)-4:]))
-
-	oidlOffset, ok := chunks[chunkOIDL]
-	if !ok {
-		return ErrInvalidObject
-	}
-	oidlSize := int64(numObjects) * int64(midx.repo.hashSize)
-	if oidlOffset < 0 || oidlOffset+oidlSize > int64(len(buf)) {
-		return ErrInvalidObject
-	}
-	oids := buf[oidlOffset : oidlOffset+oidlSize]
-
-	ooffOffset, ok := chunks[chunkOOFF]
-	if !ok {
-		return ErrInvalidObject
-	}
-	ooffSize := int64(numObjects) * 8
-	if ooffOffset < 0 || ooffOffset+ooffSize > int64(len(buf)) {
-		return ErrInvalidObject
-	}
-	offsets := buf[ooffOffset : ooffOffset+ooffSize]
-
-	var largeOffs []byte
-	if loffOffset, ok := chunks[chunkLOFF]; ok {
-		loffEnd := int64(len(buf))
-		for _, offset := range chunks {
-			if offset > loffOffset && offset < loffEnd {
-				loffEnd = offset
-			}
-		}
-		if loffOffset < 0 || loffOffset > int64(len(buf)) {
-			return ErrInvalidObject
-		}
-		largeOffs = buf[loffOffset:loffEnd]
-	}
-
-	midx.numPacks = numPacks
-	midx.numObjects = numObjects
-	midx.packNames = packNames
-	midx.fanout = fanout
-	midx.oids = oids
-	midx.offsets = offsets
-	midx.largeOffs = largeOffs
-	return nil
-}
-
-func (midx *multiPackIndex) lookup(id Hash) (packlocation, error) {
-	if len(midx.data) == 0 {
-		err := midx.ensureLoaded()
-		if err != nil {
-			return packlocation{}, err
-		}
-	}
-
-	if id.size != midx.repo.hashSize {
-		return packlocation{}, fmt.Errorf("furgit: hash size mismatch: got %d, expected %d", id.size, midx.repo.hashSize)
-	}
-
-	first := int(id.data[0])
-	var lo int
-	if first > 0 {
-		lo = int(readBE32(midx.fanout[(first-1)*4 : first*4]))
-	}
-	hi := int(readBE32(midx.fanout[first*4 : (first+1)*4]))
-
-	idx, found := bsearchHash(midx.oids, midx.repo.hashSize, lo, hi, id)
-	if !found {
-		return packlocation{}, ErrNotFound
-	}
-
-	offsetEntry := midx.offsets[idx*8 : (idx+1)*8]
-	packIntID := readBE32(offsetEntry[0:4])
-	offset := readBE32(offsetEntry[4:8])
-
-	if int(packIntID) >= len(midx.packNames) {
-		return packlocation{}, ErrInvalidObject
-	}
-
-	var finalOffset uint64
-	if offset&0x80000000 != 0 {
-		if len(midx.largeOffs) == 0 {
-			return packlocation{}, ErrInvalidObject
-		}
-		largeIdx := int(offset & 0x7fffffff)
-		if largeIdx*8+8 > len(midx.largeOffs) {
-			return packlocation{}, ErrInvalidObject
-		}
-		finalOffset = readBE64(midx.largeOffs[largeIdx*8 : largeIdx*8+8])
-	} else {
-		finalOffset = uint64(offset)
-	}
-
-	packName := midx.packNames[packIntID]
-	packPath := filepath.Join("objects", "pack", packName)
-
-	return packlocation{
-		PackPath: packPath,
-		Offset:   finalOffset,
-	}, nil
-}
-
-func (repo *Repository) multiPackIndex() (*multiPackIndex, error) {
-	repo.midxOnce.Do(func() {
-		repo.midx, repo.midxErr = repo.loadMultiPackIndex()
-	})
-	return repo.midx, repo.midxErr
-}
-
-func (repo *Repository) loadMultiPackIndex() (*multiPackIndex, error) {
-	midx := &multiPackIndex{repo: repo}
-	err := midx.ensureLoaded()
-	if err != nil {
-		if os.IsNotExist(err) {
-			return nil, ErrNotFound
-		}
-		return nil, err
-	}
-	return midx, nil
-}
diff --git a/pack_pack.go b/pack_pack.go
index 2f9cd513..3913d580 100644
--- a/pack_pack.go
+++ b/pack_pack.go
@@ -34,19 +34,6 @@ func (repo *Repository) packRead(id Hash) (StoredObject, error) {
 }
 
 func (repo *Repository) packIndexFind(id Hash) (packlocation, error) {
-	midx, err := repo.multiPackIndex()
-	if err == nil {
-		loc, err := midx.lookup(id)
-		if err == nil {
-			return loc, nil
-		}
-		if !errors.Is(err, ErrNotFound) {
-			return packlocation{}, err
-		}
-	} else if !errors.Is(err, ErrNotFound) {
-		return packlocation{}, err
-	}
-
 	idxs, err := repo.packIndexes()
 	if err != nil {
 		return packlocation{}, err
diff --git a/repo.go b/repo.go
index 634351f2..da39cb22 100644
--- a/repo.go
+++ b/repo.go
@@ -27,10 +27,6 @@ type Repository struct {
 	packIdx     []*packIndex
 	packIdxErr  error
 
-	midxOnce sync.Once
-	midx     *multiPackIndex
-	midxErr  error
-
 	packFiles   map[string]*packFile
 	packFilesMu sync.RWMutex
 	closeOnce   sync.Once
@@ -117,12 +113,6 @@ func (repo *Repository) Close() error {
 				}
 			}
 		}
-		if repo.midx != nil {
-			err := repo.midx.Close()
-			if err != nil && closeErr == nil {
-				closeErr = err
-			}
-		}
 	})
 	return closeErr
 }