93 lines
2 KiB
Go
93 lines
2 KiB
Go
package change
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import (
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"bytes"
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"encoding/gob"
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"fmt"
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"github.com/lbryio/claimtrie/claim"
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"github.com/pkg/errors"
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"github.com/syndtr/goleveldb/leveldb"
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)
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// List ...
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type List struct {
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db *leveldb.DB
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name string
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chgs []*Change
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err error
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}
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// NewChangeList ...
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func NewChangeList(db *leveldb.DB, name string) *List {
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return &List{db: db, name: name}
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}
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// Changes returns the Changes in the list.
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func (cl *List) Changes() []*Change {
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return cl.chgs
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}
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// Load loads Changes from database.
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func (cl *List) Load() *List {
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if cl.err == nil {
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cl.chgs, cl.err = loadChanges(cl.db, cl.name)
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}
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return cl
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}
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// Save saves Changes to database.
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func (cl *List) Save() *List {
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if cl.err == nil {
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cl.err = saveChanges(cl.db, cl.name, cl.chgs)
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}
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return cl
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}
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// Append appenda a Change to the Changes in the list.
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func (cl *List) Append(chg *Change) *List {
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cl.chgs = append(cl.chgs, chg)
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return cl
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}
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// Truncate truncates Changes that has Heiht larger than ht.
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func (cl *List) Truncate(ht claim.Height) *List {
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for i, chg := range cl.chgs {
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if chg.Height > ht {
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cl.chgs = cl.chgs[:i]
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break
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}
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}
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return cl
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}
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// Dump prints out the Changes in the list. (Debugging only.)
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func (cl *List) Dump() *List {
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for i, chg := range cl.chgs {
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fmt.Printf("chgs[%d] %s\n", i, chg)
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}
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return cl
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}
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func loadChanges(db *leveldb.DB, name string) ([]*Change, error) {
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data, err := db.Get([]byte(name), nil)
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if err == leveldb.ErrNotFound {
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return nil, nil
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} else if err != nil {
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return nil, errors.Wrapf(err, "db.Get(%s)", name)
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}
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var chgs []*Change
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if err = gob.NewDecoder(bytes.NewBuffer(data)).Decode(&chgs); err != nil {
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return nil, errors.Wrapf(err, "gob.Decode(&blk)")
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}
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return chgs, nil
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}
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func saveChanges(db *leveldb.DB, name string, chgs []*Change) error {
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buf := bytes.NewBuffer(nil)
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if err := gob.NewEncoder(buf).Encode(&chgs); err != nil {
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return errors.Wrapf(err, "gob.Decode(&blk)")
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}
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return errors.Wrapf(db.Put([]byte(name), buf.Bytes(), nil), "db.put(%s, buf)", name)
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}
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