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111 lines
2.7 KiB
111 lines
2.7 KiB
package db
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import . "github.com/tendermint/tmlibs/common"
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type DB interface {
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Get([]byte) []byte // NOTE: returns nil iff never set or deleted.
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Set([]byte, []byte)
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SetSync([]byte, []byte)
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Delete([]byte)
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DeleteSync([]byte)
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Close()
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NewBatch() Batch
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Iterator() Iterator
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// For debugging
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Print()
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// Stats returns a map of property values for all keys and the size of the cache.
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Stats() map[string]string
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// CacheWrap wraps the DB w/ a CacheDB.
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CacheWrap() interface{}
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}
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type Batch interface {
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Set(key, value []byte)
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Delete(key []byte)
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Write()
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}
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/*
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Usage:
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for itr.Seek(mykey); itr.Valid(); itr.Next() {
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k, v := itr.Key(); itr.Value()
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....
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}
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*/
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type Iterator interface {
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// Seek moves the iterator the position of the key given or, if the key
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// doesn't exist, the next key that does exist in the database. If the key
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// doesn't exist, and there is no next key, the Iterator becomes invalid.
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Seek(key []byte)
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// Valid returns false only when an Iterator has iterated past either the
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// first or the last key in the database.
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Valid() bool
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// Next moves the iterator to the next sequential key in the database, as
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// defined by the Comparator in the ReadOptions used to create this Iterator.
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//
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// If Valid returns false, this method will panic.
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Next()
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// Prev moves the iterator to the previous sequential key in the database, as
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// defined by the Comparator in the ReadOptions used to create this Iterator.
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//
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// If Valid returns false, this method will panic.
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Prev()
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// Key returns the key of the cursor.
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//
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// If Valid returns false, this method will panic.
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Key() []byte
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// Value returns the key of the cursor.
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//
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// If Valid returns false, this method will panic.
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Value() []byte
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// GetError returns an IteratorError from LevelDB if it had one during
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// iteration.
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//
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// This method is safe to call when Valid returns false.
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GetError() error
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// Close deallocates the given Iterator.
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Close()
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}
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//-----------------------------------------------------------------------------
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// Main entry
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const (
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LevelDBBackendStr = "leveldb" // legacy, defaults to goleveldb.
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CLevelDBBackendStr = "cleveldb"
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GoLevelDBBackendStr = "goleveldb"
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MemDBBackendStr = "memdb"
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FSDBBackendStr = "fsdb" // using the filesystem naively
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)
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type dbCreator func(name string, dir string) (DB, error)
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var backends = map[string]dbCreator{}
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func registerDBCreator(backend string, creator dbCreator, force bool) {
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_, ok := backends[backend]
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if !force && ok {
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return
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}
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backends[backend] = creator
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}
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func NewDB(name string, backend string, dir string) DB {
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db, err := backends[backend](name, dir)
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if err != nil {
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PanicSanity(Fmt("Error initializing DB: %v", err))
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}
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return db
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}
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