/
reflist.go
399 lines (339 loc) · 10.1 KB
/
reflist.go
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package deb
import (
"bytes"
"encoding/json"
"github.com/AlekSi/pointer"
"github.com/ugorji/go/codec"
"sort"
)
// PackageRefList is a list of keys of packages, this is basis for snapshot
// and similar stuff
//
// Refs are sorted in lexicographical order
type PackageRefList struct {
// List of package keys
Refs [][]byte
}
// Verify interface
var (
_ sort.Interface = &PackageRefList{}
)
// NewPackageRefList creates empty PackageRefList
func NewPackageRefList() *PackageRefList {
return &PackageRefList{}
}
// NewPackageRefListFromPackageList creates PackageRefList from PackageList
func NewPackageRefListFromPackageList(list *PackageList) *PackageRefList {
reflist := &PackageRefList{}
reflist.Refs = make([][]byte, list.Len())
i := 0
for _, p := range list.packages {
reflist.Refs[i] = p.Key("")
i++
}
sort.Sort(reflist)
return reflist
}
// Len returns number of refs
func (l *PackageRefList) Len() int {
return len(l.Refs)
}
// Swap swaps two refs
func (l *PackageRefList) Swap(i, j int) {
l.Refs[i], l.Refs[j] = l.Refs[j], l.Refs[i]
}
// Compare compares two refs in lexographical order
func (l *PackageRefList) Less(i, j int) bool {
return bytes.Compare(l.Refs[i], l.Refs[j]) < 0
}
// Encode does msgpack encoding of PackageRefList
func (l *PackageRefList) Encode() []byte {
var buf bytes.Buffer
encoder := codec.NewEncoder(&buf, &codec.MsgpackHandle{})
encoder.Encode(l)
return buf.Bytes()
}
// Decode decodes msgpack representation into PackageRefLit
func (l *PackageRefList) Decode(input []byte) error {
decoder := codec.NewDecoderBytes(input, &codec.MsgpackHandle{})
return decoder.Decode(l)
}
// ForEach calls handler for each package ref in list
func (l *PackageRefList) ForEach(handler func([]byte) error) error {
var err error
for _, p := range l.Refs {
err = handler(p)
if err != nil {
return err
}
}
return err
}
// Has checks whether package is part of reflist
func (l *PackageRefList) Has(p *Package) bool {
key := p.Key("")
i := sort.Search(len(l.Refs), func(j int) bool { return bytes.Compare(l.Refs[j], key) >= 0 })
return i < len(l.Refs) && bytes.Compare(l.Refs[i], key) == 0
}
// Strings builds list of strings with package keys
func (l *PackageRefList) Strings() []string {
if l == nil {
return []string{}
}
result := make([]string, l.Len())
for i := 0; i < l.Len(); i++ {
result[i] = string(l.Refs[i])
}
return result
}
// Substract returns all packages in l that are not in r
func (l *PackageRefList) Substract(r *PackageRefList) *PackageRefList {
result := &PackageRefList{Refs: make([][]byte, 0, 128)}
// pointer to left and right reflists
il, ir := 0, 0
// length of reflists
ll, lr := l.Len(), r.Len()
for il < ll || ir < lr {
if il == ll {
// left list exhausted, we got the result
break
}
if ir == lr {
// right list exhausted, append what is left to result
result.Refs = append(result.Refs, l.Refs[il:]...)
break
}
rel := bytes.Compare(l.Refs[il], r.Refs[ir])
if rel == 0 {
// r contains entry from l, so we skip it
il++
ir++
} else if rel < 0 {
// item il is not in r, append
result.Refs = append(result.Refs, l.Refs[il])
il++
} else {
// skip over to next item in r
ir++
}
}
return result
}
// PackageDiff is a difference between two packages in a list.
//
// If left & right are present, difference is in package version
// If left is nil, package is present only in right
// If right is nil, package is present only in left
type PackageDiff struct {
Left, Right *Package
}
// Check interface
var (
_ json.Marshaler = PackageDiff{}
)
// MarshalJSON implements json.Marshaler interface
func (d PackageDiff) MarshalJSON() ([]byte, error) {
serialized := struct {
Left, Right *string
}{}
if d.Left != nil {
serialized.Left = pointer.ToString(string(d.Left.Key("")))
}
if d.Right != nil {
serialized.Right = pointer.ToString(string(d.Right.Key("")))
}
return json.Marshal(serialized)
}
// PackageDiffs is a list of PackageDiff records
type PackageDiffs []PackageDiff
// Diff calculates difference between two reflists
func (l *PackageRefList) Diff(r *PackageRefList, packageCollection *PackageCollection) (result PackageDiffs, err error) {
result = make(PackageDiffs, 0, 128)
// pointer to left and right reflists
il, ir := 0, 0
// length of reflists
ll, lr := l.Len(), r.Len()
// cached loaded packages on the left & right
pl, pr := (*Package)(nil), (*Package)(nil)
// until we reached end of both lists
for il < ll || ir < lr {
// if we've exhausted left list, pull the rest from the right
if il == ll {
pr, err = packageCollection.ByKey(r.Refs[ir])
if err != nil {
return nil, err
}
result = append(result, PackageDiff{Left: nil, Right: pr})
ir++
continue
}
// if we've exhausted right list, pull the rest from the left
if ir == lr {
pl, err = packageCollection.ByKey(l.Refs[il])
if err != nil {
return nil, err
}
result = append(result, PackageDiff{Left: pl, Right: nil})
il++
continue
}
// refs on both sides are present, load them
rl, rr := l.Refs[il], r.Refs[ir]
// compare refs
rel := bytes.Compare(rl, rr)
if rel == 0 {
// refs are identical, so are packages, advance pointer
il++
ir++
pl, pr = nil, nil
} else {
// load pl & pr if they haven't been loaded before
if pl == nil {
pl, err = packageCollection.ByKey(rl)
if err != nil {
return nil, err
}
}
if pr == nil {
pr, err = packageCollection.ByKey(rr)
if err != nil {
return nil, err
}
}
// otherwise pl or pr is missing on one of the sides
if rel < 0 {
// compaction: +(,A) -(B,) --> !(A,B)
if len(result) > 0 && result[len(result)-1].Left == nil && result[len(result)-1].Right.Name == pl.Name &&
result[len(result)-1].Right.Architecture == pl.Architecture {
result[len(result)-1] = PackageDiff{Left: pl, Right: result[len(result)-1].Right}
} else {
result = append(result, PackageDiff{Left: pl, Right: nil})
}
il++
pl = nil
} else {
// compaction: -(A,) +(,B) --> !(A,B)
if len(result) > 0 && result[len(result)-1].Right == nil && result[len(result)-1].Left.Name == pr.Name &&
result[len(result)-1].Left.Architecture == pr.Architecture {
result[len(result)-1] = PackageDiff{Left: result[len(result)-1].Left, Right: pr}
} else {
result = append(result, PackageDiff{Left: nil, Right: pr})
}
ir++
pr = nil
}
}
}
return
}
// Merge merges reflist r into current reflist. If overrideMatching, merge
// replaces matching packages (by architecture/name) with reference from r.
// If ignoreConflicting is set, all packages are preserved, otherwise conflciting
// packages are overwritten with packages from "right" snapshot.
func (l *PackageRefList) Merge(r *PackageRefList, overrideMatching, ignoreConflicting bool) (result *PackageRefList) {
var overriddenArch, overridenName []byte
// pointer to left and right reflists
il, ir := 0, 0
// length of reflists
ll, lr := l.Len(), r.Len()
result = &PackageRefList{}
result.Refs = make([][]byte, 0, ll+lr)
// until we reached end of both lists
for il < ll || ir < lr {
// if we've exhausted left list, pull the rest from the right
if il == ll {
result.Refs = append(result.Refs, r.Refs[ir:]...)
break
}
// if we've exhausted right list, pull the rest from the left
if ir == lr {
result.Refs = append(result.Refs, l.Refs[il:]...)
break
}
// refs on both sides are present, load them
rl, rr := l.Refs[il], r.Refs[ir]
// compare refs
rel := bytes.Compare(rl, rr)
if rel == 0 {
// refs are identical, so are packages, advance pointer
result.Refs = append(result.Refs, l.Refs[il])
il++
ir++
overridenName = nil
overriddenArch = nil
} else {
partsL := bytes.Split(rl, []byte(" "))
archL, nameL, versionL := partsL[0][1:], partsL[1], partsL[2]
partsR := bytes.Split(rr, []byte(" "))
archR, nameR, versionR := partsR[0][1:], partsR[1], partsR[2]
if !ignoreConflicting && bytes.Equal(archL, archR) && bytes.Equal(nameL, nameR) && bytes.Equal(versionL, versionR) {
// conflicting duplicates with same arch, name, version, but different file hash
result.Refs = append(result.Refs, r.Refs[ir])
il++
ir++
overridenName = nil
overriddenArch = nil
continue
}
if overrideMatching {
if bytes.Equal(archL, overriddenArch) && bytes.Equal(nameL, overridenName) {
// this package has already been overriden on the right
il++
continue
}
if bytes.Equal(archL, archR) && bytes.Equal(nameL, nameR) {
// override with package from the right
result.Refs = append(result.Refs, r.Refs[ir])
il++
ir++
overriddenArch = archL
overridenName = nameL
continue
}
}
// otherwise append smallest of two
if rel < 0 {
result.Refs = append(result.Refs, l.Refs[il])
il++
} else {
result.Refs = append(result.Refs, r.Refs[ir])
ir++
overridenName = nil
overriddenArch = nil
}
}
}
return
}
// FilterLatestRefs takes in a reflist with potentially multiples of the same
// packages and reduces it to only the latest of each package. The operations
// are done in-place. This implements a "latest wins" approach which can be used
// while merging two or more snapshots together.
func (l *PackageRefList) FilterLatestRefs() {
var (
lastArch, lastName, lastVer []byte
arch, name, ver []byte
parts [][]byte
)
for i := 0; i < len(l.Refs); i++ {
parts = bytes.Split(l.Refs[i][1:], []byte(" "))
arch, name, ver = parts[0], parts[1], parts[2]
if bytes.Equal(arch, lastArch) && bytes.Equal(name, lastName) {
// Two packages are identical, check version and only one wins
vres := CompareVersions(string(ver), string(lastVer))
// Remove the older refs from the result
if vres > 0 {
// ver[i] > ver[i-1], remove element i-1
l.Refs = append(l.Refs[:i-1], l.Refs[i:]...)
} else {
// ver[i] < ver[i-1], remove element i
l.Refs = append(l.Refs[:i], l.Refs[i+1:]...)
arch, name, ver = lastArch, lastName, lastVer
}
// Compensate for the reduced set
i -= 1
}
lastArch, lastName, lastVer = arch, name, ver
}
return
}