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New canonical Iterator

pull/1842/head
Jae Kwon 7 years ago
parent
commit
50a30aafc1
3 changed files with 113 additions and 88 deletions
  1. +2
    -0
      db/cache_db.go
  2. +0
    -88
      db/db.go
  3. +111
    -0
      db/types.go

+ 2
- 0
db/cache_db.go View File

@ -1,3 +1,4 @@
/*
package db
import (
@ -229,3 +230,4 @@ func (cww *cwwMutex) TryWriteLock(version interface{}) bool {
cww.written = new(int32)
return true
}
*/

+ 0
- 88
db/db.go View File

@ -1,93 +1,5 @@
package db
import . "github.com/tendermint/tmlibs/common"
type DB interface {
Get([]byte) []byte // NOTE: returns nil iff never set or deleted.
Set([]byte, []byte)
SetSync([]byte, []byte)
Delete([]byte)
DeleteSync([]byte)
Close()
NewBatch() Batch
Iterator() Iterator
// For debugging
Print()
// Stats returns a map of property values for all keys and the size of the cache.
Stats() map[string]string
// CacheDB wraps the DB w/ a cache.
CacheDB() CacheDB
}
type CacheDB interface {
DB
Write() // Write to the underlying DB
}
type SetDeleter interface {
Set(key, value []byte)
Delete(key []byte)
}
type Batch interface {
SetDeleter
Write()
}
/*
Usage:
for itr.Seek(mykey); itr.Valid(); itr.Next() {
k, v := itr.Key(); itr.Value()
....
}
*/
type Iterator interface {
// Seek moves the iterator the position of the key given or, if the key
// doesn't exist, the next key that does exist in the database. If the key
// doesn't exist, and there is no next key, the Iterator becomes invalid.
Seek(key []byte)
// Valid returns false only when an Iterator has iterated past either the
// first or the last key in the database.
Valid() bool
// Next moves the iterator to the next sequential key in the database, as
// defined by the Comparator in the ReadOptions used to create this Iterator.
//
// If Valid returns false, this method will panic.
Next()
// Prev moves the iterator to the previous sequential key in the database, as
// defined by the Comparator in the ReadOptions used to create this Iterator.
//
// If Valid returns false, this method will panic.
Prev()
// Key returns the key of the cursor.
//
// If Valid returns false, this method will panic.
Key() []byte
// Value returns the key of the cursor.
//
// If Valid returns false, this method will panic.
Value() []byte
// GetError returns an IteratorError from LevelDB if it had one during
// iteration.
//
// This method is safe to call when Valid returns false.
GetError() error
// Close deallocates the given Iterator.
Close()
}
//-----------------------------------------------------------------------------
// Main entry


+ 111
- 0
db/types.go View File

@ -0,0 +1,111 @@
package db
type DB interface {
// Get returns nil iff key doesn't exist. Panics on nil key.
Get([]byte) []byte
// Has checks if a key exists. Panics on nil key.
Has(key []byte) bool
// Set sets the key. Panics on nil key.
Set([]byte, []byte)
SetSync([]byte, []byte)
// Delete deletes the key. Panics on nil key.
Delete([]byte)
DeleteSync([]byte)
// Iterator over a domain of keys in ascending order. End is exclusive.
// Start must be less than end, or the Iterator is invalid.
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
Iterator(start, end []byte) Iterator
// Iterator over a domain of keys in descending order. End is exclusive.
// Start must be greater than end, or the Iterator is invalid.
// CONTRACT: No writes may happen within a domain while an iterator exists over it.
ReverseIterator(start, end []byte) Iterator
// Releases the connection.
Close()
// Creates a batch for atomic updates.
NewBatch() Batch
// For debugging
Print()
// Stats returns a map of property values for all keys and the size of the cache.
Stats() map[string]string
}
//----------------------------------------
// Batch
type Batch interface {
SetDeleter
Write()
}
type SetDeleter interface {
Set(key, value []byte)
Delete(key []byte)
}
//----------------------------------------
/*
Usage:
for itr.Seek(mykey); itr.Valid(); itr.Next() {
k, v := itr.Key(); itr.Value()
....
}
*/
type Iterator interface {
// The start & end (exclusive) limits to iterate over.
// If end < start, then the Iterator goes in reverse order.
//
// A domain of ([]byte{12, 13}, []byte{12, 14}) will iterate
// over anything with the prefix []byte{12, 13}.
//
// The smallest key is the empty byte array []byte{}.
// The largest key is the nil byte array []byte(nil).
Domain() (start []byte, end []byte)
// Valid returns whether the current position is valid.
// Once invalid, an Iterator is forever invalid.
Valid() bool
// Next moves the iterator to the next sequential key in the database, as
// defined by the Comparator in the ReadOptions used to create this Iterator.
//
// If Valid returns false, this method will panic.
Next()
// Prev moves the iterator to the previous sequential key in the database, as
// defined by the Comparator in the ReadOptions used to create this Iterator.
//
// If Valid returns false, this method will panic.
Prev()
// Key returns the key of the cursor.
//
// If Valid returns false, this method will panic.
Key() []byte
// Value returns the key of the cursor.
//
// If Valid returns false, this method will panic.
Value() []byte
// GetError returns an IteratorError from LevelDB if it had one during
// iteration.
//
// This method is safe to call when Valid returns false.
GetError() error
// Close deallocates the given Iterator.
Close()
}

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