144 lines
3.4 KiB
Go
144 lines
3.4 KiB
Go
package store
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import (
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"bytes"
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"github.com/tendermint/go-wire/data"
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"github.com/tendermint/tmlibs/db"
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)
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//----------------------------------------
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// MultiStore
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type MultiStore interface {
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// Last commit, or the zero CommitID.
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// If not zero, CommitID.Version is CurrentVersion()-1.
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LastCommitID() CommitID
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// Current version being worked on now, not yet committed.
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// Should be greater than 0.
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CurrentVersion() int64
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// Cache wrap MultiStore.
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// NOTE: Caller should probably not call .Write() on each, but
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// call CacheMultiStore.Write().
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CacheMultiStore() CacheMultiStore
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// Convenience
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GetStore(name string) interface{}
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GetKVStore(name string) KVStore
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}
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type CacheMultiStore interface {
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MultiStore
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Write() // Writes operations to underlying KVStore
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}
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type CommitStore interface {
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Committer
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CacheWrapper
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}
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type CommitStoreLoader func(id CommitID) (CommitStore, error)
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type Committer interface {
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// Commit persists the state to disk.
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Commit() CommitID
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}
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//----------------------------------------
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// KVStore
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// KVStore is a simple interface to get/set data
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type KVStore interface {
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// Get returns nil iff key doesn't exist. Panics on nil key.
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Get(key []byte) []byte
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// Has checks if a key exists. Panics on nil key.
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Has(key []byte) bool
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// Set sets the key. Panics on nil key.
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Set(key, value []byte)
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// Delete deletes the key. Panics on nil key.
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Delete(key []byte)
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// Iterator over a domain of keys in ascending order. End is exclusive.
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// Start must be less than end, or the Iterator is invalid.
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// CONTRACT: No writes may happen within a domain while an iterator exists over it.
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Iterator(start, end []byte) Iterator
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// Iterator over a domain of keys in descending order. End is exclusive.
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// Start must be greater than end, or the Iterator is invalid.
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// CONTRACT: No writes may happen within a domain while an iterator exists over it.
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ReverseIterator(start, end []byte) Iterator
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}
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// db.DB implements KVStore so we can CacheKVStore it.
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var _ KVStore = db.DB(nil)
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// Alias iterator to db's Iterator for convenience.
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type Iterator = db.Iterator
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// CacheKVStore cache-wraps a KVStore. After calling .Write() on the
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// CacheKVStore, all previously created CacheKVStores on the object expire.
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type CacheKVStore interface {
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KVStore
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Write() // Writes operations to underlying KVStore
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}
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//----------------------------------------
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// CacheWrap
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/*
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CacheWrap() makes the most appropriate cache-wrap. For example,
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IAVLStore.CacheWrap() returns a CacheKVStore.
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CacheWrap() should not return a Committer, since Commit() on
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cache-wraps make no sense. It can return KVStore, HeapStore,
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SpaceStore, etc.
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*/
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type CacheWrapper interface {
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CacheWrap() CacheWrap
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}
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type CacheWrap interface {
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// Write syncs with the underlying store.
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Write()
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// CacheWrap recursively wraps again.
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CacheWrap() CacheWrap
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}
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//----------------------------------------
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// etc
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type KVPair struct {
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Key data.Bytes
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Value data.Bytes
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}
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// CommitID contains the tree version number and its merkle root.
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type CommitID struct {
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Version int64
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Hash []byte
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}
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func (cid CommitID) IsZero() bool {
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return cid.Version == 0 && len(cid.Hash) == 0
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}
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// bytes.Compare but bounded on both sides by nil.
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// both (k1, nil) and (nil, k2) return -1
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func keyCompare(k1, k2 []byte) int {
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if k1 == nil && k2 == nil {
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return 0
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} else if k1 == nil || k2 == nil {
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return -1
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}
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return bytes.Compare(k1, k2)
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}
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