db

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 Go to latest Published: Feb 25, 2022 License: Apache-2.0 Imports: 21 Imported by: 2

README

Tendermint DB

Test Lint

Common database interface for various database backends. Primarily meant for applications built on Tendermint, such as the Cosmos SDK, but can be used independently of these as well.

Minimum Go Version

Go 1.13+

Supported Database Backends

  • GoLevelDB [stable]: A pure Go implementation of LevelDB (see below). Currently the default on-disk database used in the Cosmos SDK.

  • MemDB [stable]: An in-memory database using Google's B-tree package. Has very high performance both for reads, writes, and range scans, but is not durable and will lose all data on process exit. Does not support transactions. Suitable for e.g. caches, working sets, and tests. Used for IAVL working sets when the pruning strategy allows it.

  • LevelDB [experimental]: A Go wrapper around LevelDB. Uses LSM-trees for on-disk storage, which have good performance for write-heavy workloads, particularly on spinning disks, but requires periodic compaction to maintain decent read performance and reclaim disk space. Does not support transactions.

  • BoltDB [experimental]: A fork of BoltDB. Uses B+trees for on-disk storage, which have good performance for read-heavy workloads and range scans. Supports serializable ACID transactions.

  • RocksDB [experimental]: A Go wrapper around RocksDB. Similarly to LevelDB (above) it uses LSM-trees for on-disk storage, but is optimized for fast storage media such as SSDs and memory. Supports atomic transactions, but not full ACID transactions.

Meta-databases

  • PrefixDB [stable]: A database which wraps another database and uses a static prefix for all keys. This allows multiple logical databases to be stored in a common underlying databases by using different namespaces. Used by the Cosmos SDK to give different modules their own namespaced database in a single application database.

  • RemoteDB [experimental]: A database that connects to distributed Tendermint db instances via gRPC. This can help with detaching difficult deployments such as LevelDB, and can also ease dependency management for Tendermint developers.

Tests

To test common databases, run make test. If all databases are available on the local machine, use make test-all to test them all.

Documentation

Index

Constants

View Source 
const (
	BYTE = 1 << (10 * iota)
	KILOBYTE
	MEGABYTE
	GIGABYTE
	TERABYTE
	PETABYTE
	EXABYTE
)

Variables

This section is empty.

Functions

func FileExists 

func FileExists(filePath string) bool

func IsKeyInDomain 

func IsKeyInDomain(key, start, end []byte) bool

See DB interface documentation for more information.

Types

type BackendType 

type BackendType string
const (
	// GoLevelDBBackend represents goleveldb (github.com/syndtr/goleveldb - most
	// popular implementation)
	//   - pure go
	//   - stable
	GoLevelDBBackend BackendType = "goleveldb"
	// CLevelDBBackend represents cleveldb (uses levigo wrapper)
	//   - fast
	//   - requires gcc
	//   - use cleveldb build tag (go build -tags cleveldb)
	CLevelDBBackend BackendType = "cleveldb"
	// MemDBBackend represents in-memory key value store, which is mostly used
	// for testing.
	MemDBBackend BackendType = "memdb"
	// BoltDBBackend represents bolt (uses etcd's fork of bolt -
	// github.com/etcd-io/bbolt)
	//   - EXPERIMENTAL
	//   - may be faster is some use-cases (random reads - indexer)
	//   - use boltdb build tag (go build -tags boltdb)
	BoltDBBackend BackendType = "boltdb"
	// RocksDBBackend represents rocksdb (uses github.com/tecbot/gorocksdb)
	//   - EXPERIMENTAL
	//   - requires gcc
	//   - use rocksdb build tag (go build -tags rocksdb)
	RocksDBBackend BackendType = "rocksdb"
	// UnknownDBBackend unknown db type
	UnknownDBBackend BackendType = "unknown"

	FlagGoLeveldbOpts = "goleveldb.opts"
	FlagRocksdbOpts   = "rocksdb.opts"
)

These are valid backend types.

type Batch 

type Batch interface {
	SetDeleter

	// Write writes the batch, possibly without flushing to disk. Only Close() can be called after,
	// other methods will panic.
	Write() error

	// WriteSync writes the batch and flushes it to disk. Only Close() can be called after, other
	// methods will panic.
	WriteSync() error

	// Close closes the batch. It is idempotent, but any other calls afterwards will panic.
	Close()
}

Batch represents a group of writes. They may or may not be written atomically depending on the backend. Callers must call Close on the batch when done.

As with DB, given keys and values should be considered read-only, and must not be modified after passing them to the batch.

type DB 

type DB interface {
	// Get fetches the value of the given key, or nil if it does not exist.
	// CONTRACT: key, value readonly []byte
	Get([]byte) ([]byte, error)

	// GetUnsafeValue fetches the value of the given key, if error occurs while fetching value, it returns (nil, err),
	// else, it will pass the value to the UnsafeValueProcessor and return what the UnsafeValueProcessor returns
	// CONTRACT: value is readonly and can not be referenced after return
	GetUnsafeValue(key []byte, processor UnsafeValueProcessor) (interface{}, error)

	// Has checks if a key exists.
	// CONTRACT: key, value readonly []byte
	Has(key []byte) (bool, error)

	// Set sets the value for the given key, replacing it if it already exists.
	// CONTRACT: key, value readonly []byte
	Set([]byte, []byte) error

	// SetSync sets the value for the given key, and flushes it to storage before returning.
	SetSync([]byte, []byte) error

	// Delete deletes the key, or does nothing if the key does not exist.
	// CONTRACT: key readonly []byte
	Delete([]byte) error

	// DeleteSync deletes the key, and flushes the delete to storage before returning.
	DeleteSync([]byte) error

	// Iterator returns an iterator over a domain of keys, in ascending order. The caller must call
	// Close when done. End is exclusive, and start must be less than end. A nil start iterates
	// from the first key, and a nil end iterates to the last key (inclusive).
	// CONTRACT: No writes may happen within a domain while an iterator exists over it.
	// CONTRACT: start, end readonly []byte
	Iterator(start, end []byte) (Iterator, error)

	// ReverseIterator returns an iterator over a domain of keys, in descending order. The caller
	// must call Close when done. End is exclusive, and start must be less than end. A nil end
	// iterates from the last key (inclusive), and a nil start iterates to the first key (inclusive).
	// CONTRACT: No writes may happen within a domain while an iterator exists over it.
	// CONTRACT: start, end readonly []byte
	ReverseIterator(start, end []byte) (Iterator, error)

	// Close closes the database connection.
	Close() error

	// NewBatch creates a batch for atomic updates. The caller must call Batch.Close.
	NewBatch() Batch

	// Print is used for debugging.
	Print() error

	// Stats returns a map of property values for all keys and the size of the cache.
	Stats() map[string]string
}

DB is the main interface for all database backends. DBs are concurrency-safe. Callers must call Close on the database when done.

Keys and values can be empty, or nil which is interpreted as an empty byte slice. Keys and values should be considered read-only, both when returned and when given, and must be copied before they are modified.

func NewDB 

func NewDB(name string, backend BackendType, dir string) DB

NewDB creates a new database of type backend with the given name. NOTE: function panics if:

  • backend is unknown (not registered)
  • creator function, provided during registration, returns error

type GoLevelDB 

type GoLevelDB struct {
	// contains filtered or unexported fields
}

func NewGoLevelDB 

func NewGoLevelDB(name string, dir string) (*GoLevelDB, error)

func NewGoLevelDBWithOpts 

func NewGoLevelDBWithOpts(name string, dir string, o *opt.Options) (*GoLevelDB, error)

func (*GoLevelDB) Close 

func (db *GoLevelDB) Close() error

Close implements DB.

func (*GoLevelDB) DB 

func (db *GoLevelDB) DB() *leveldb.DB

func (*GoLevelDB) Delete 

func (db *GoLevelDB) Delete(key []byte) error

Delete implements DB.

func (*GoLevelDB) DeleteSync 

func (db *GoLevelDB) DeleteSync(key []byte) error

DeleteSync implements DB.

func (*GoLevelDB) Get 

func (db *GoLevelDB) Get(key []byte) ([]byte, error)

Get implements DB.

func (*GoLevelDB) GetUnsafeValue 

func (db *GoLevelDB) GetUnsafeValue(key []byte, processor UnsafeValueProcessor) (interface{}, error)

func (*GoLevelDB) Has 

func (db *GoLevelDB) Has(key []byte) (bool, error)

Has implements DB.

func (*GoLevelDB) Iterator 

func (db *GoLevelDB) Iterator(start, end []byte) (Iterator, error)

Iterator implements DB.

func (*GoLevelDB) NewBatch 

func (db *GoLevelDB) NewBatch() Batch

NewBatch implements DB.

func (*GoLevelDB) Print 

func (db *GoLevelDB) Print() error

Print implements DB.

func (*GoLevelDB) ReverseIterator 

func (db *GoLevelDB) ReverseIterator(start, end []byte) (Iterator, error)

ReverseIterator implements DB.

func (*GoLevelDB) Set 

func (db *GoLevelDB) Set(key []byte, value []byte) error

Set implements DB.

func (*GoLevelDB) SetSync 

func (db *GoLevelDB) SetSync(key []byte, value []byte) error

SetSync implements DB.

func (*GoLevelDB) Stats 

func (db *GoLevelDB) Stats() map[string]string

Stats implements DB.

type Iterator 

type Iterator interface {
	// Domain returns the start (inclusive) and end (exclusive) limits of the iterator.
	// CONTRACT: start, end readonly []byte
	Domain() (start []byte, end []byte)

	// Valid returns whether the current iterator is valid. Once invalid, the Iterator remains
	// invalid forever.
	Valid() bool

	// Next moves the iterator to the next key in the database, as defined by order of iteration.
	// If Valid returns false, this method will panic.
	Next()

	// Key returns the key at the current position. Panics if the iterator is invalid.
	// CONTRACT: key readonly []byte
	Key() (key []byte)

	// Value returns the value at the current position. Panics if the iterator is invalid.
	// CONTRACT: value readonly []byte
	Value() (value []byte)

	// Error returns the last error encountered by the iterator, if any.
	Error() error

	// Close closes the iterator, relasing any allocated resources.
	Close()
}

Iterator represents an iterator over a domain of keys. Callers must call Close when done. No writes can happen to a domain while there exists an iterator over it, some backends may take out database locks to ensure this will not happen.

As with DB, keys and values should be considered read-only, and must be copied before they are modified.

Typical usage:

var itr Iterator = ... defer itr.Close() 

for ; itr.Valid(); itr.Next() {
  k, v := itr.Key(); itr.Value()
  ...
}

func IteratePrefix 

func IteratePrefix(db DB, prefix []byte) (Iterator, error)

IteratePrefix is a convenience function for iterating over a key domain restricted by prefix.

type MemDB 

type MemDB struct {
	// contains filtered or unexported fields
}

MemDB is an in-memory database backend using a B-tree for storage.

For performance reasons, all given and returned keys and values are pointers to the in-memory database, so modifying them will cause the stored values to be modified as well. All DB methods already specify that keys and values should be considered read-only, but this is especially important with MemDB.

func NewMemDB 

func NewMemDB() *MemDB

NewMemDB creates a new in-memory database.

func (*MemDB) Close 

func (db *MemDB) Close() error

Close implements DB.

func (*MemDB) Delete 

func (db *MemDB) Delete(key []byte) error

Delete implements DB.

func (*MemDB) DeleteSync 

func (db *MemDB) DeleteSync(key []byte) error

DeleteSync implements DB.

func (*MemDB) Get 

func (db *MemDB) Get(key []byte) ([]byte, error)

Get implements DB.

func (*MemDB) GetUnsafeValue 

func (db *MemDB) GetUnsafeValue(key []byte, processor UnsafeValueProcessor) (interface{}, error)

func (*MemDB) Has 

func (db *MemDB) Has(key []byte) (bool, error)

Has implements DB.

func (*MemDB) Iterator 

func (db *MemDB) Iterator(start, end []byte) (Iterator, error)

Iterator implements DB. Takes out a read-lock on the database until the iterator is closed.

func (*MemDB) NewBatch 

func (db *MemDB) NewBatch() Batch

NewBatch implements DB.

func (*MemDB) Print 

func (db *MemDB) Print() error

Print implements DB.

func (*MemDB) ReverseIterator 

func (db *MemDB) ReverseIterator(start, end []byte) (Iterator, error)

ReverseIterator implements DB. Takes out a read-lock on the database until the iterator is closed.

func (*MemDB) Set 

func (db *MemDB) Set(key []byte, value []byte) error

Set implements DB.

func (*MemDB) SetSync 

func (db *MemDB) SetSync(key []byte, value []byte) error

SetSync implements DB.

func (*MemDB) Stats 

func (db *MemDB) Stats() map[string]string

Stats implements DB.

type PrefixDB 

type PrefixDB struct {
	// contains filtered or unexported fields
}

PrefixDB wraps a namespace of another database as a logical database.

func NewPrefixDB 

func NewPrefixDB(db DB, prefix []byte) *PrefixDB

NewPrefixDB lets you namespace multiple DBs within a single DB.

func (*PrefixDB) Close 

func (pdb *PrefixDB) Close() error

Close implements DB.

func (*PrefixDB) Delete 

func (pdb *PrefixDB) Delete(key []byte) error

Delete implements DB.

func (*PrefixDB) DeleteSync 

func (pdb *PrefixDB) DeleteSync(key []byte) error

DeleteSync implements DB.

func (*PrefixDB) Get 

func (pdb *PrefixDB) Get(key []byte) ([]byte, error)

Get implements DB.

func (*PrefixDB) GetUnsafeValue 

func (pdb *PrefixDB) GetUnsafeValue(key []byte, processor UnsafeValueProcessor) (retv interface{}, err error)

func (*PrefixDB) Has 

func (pdb *PrefixDB) Has(key []byte) (bool, error)

Has implements DB.

func (*PrefixDB) Iterator 

func (pdb *PrefixDB) Iterator(start, end []byte) (Iterator, error)

Iterator implements DB.

func (*PrefixDB) NewBatch 

func (pdb *PrefixDB) NewBatch() Batch

NewBatch implements DB.

func (*PrefixDB) Print 

func (pdb *PrefixDB) Print() error

Print implements DB.

func (*PrefixDB) ReverseIterator 

func (pdb *PrefixDB) ReverseIterator(start, end []byte) (Iterator, error)

ReverseIterator implements DB.

func (*PrefixDB) Set 

func (pdb *PrefixDB) Set(key []byte, value []byte) error

Set implements DB.

func (*PrefixDB) SetSync 

func (pdb *PrefixDB) SetSync(key []byte, value []byte) error

SetSync implements DB.

func (*PrefixDB) Stats 

func (pdb *PrefixDB) Stats() map[string]string

Stats implements DB.

type SetDeleter 

type SetDeleter interface {
	// Set sets a key/value pair.
	// CONTRACT: key, value readonly []byte
	Set(key, value []byte)

	// Delete deletes a key/value pair.
	// CONTRACT: key readonly []byte
	Delete(key []byte)
}

type UnsafeValueProcessor 

type UnsafeValueProcessor func(value []byte) (interface{}, error)

UnsafeValueProcessor called after DB Get if the error of Get is nil, value is the result of DB Get. CONTRACT: value is readonly and can not be referenced after return

Source Files

View all Source files

Directories

Path Synopsis
remotedb is a package for connecting to distributed Tendermint db.DB instances.
 remotedb is a package for connecting to distributed Tendermint db.DB instances.
grpcdb
grpcdb is the distribution of Tendermint's db.DB instances using the gRPC transport to decouple local db.DB usages from applications, to using them over a network in a highly performant manner.
 grpcdb is the distribution of Tendermint's db.DB instances using the gRPC transport to decouple local db.DB usages from applications, to using them over a network in a highly performant manner.
proto

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