client

package
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 Go to latest Published: Sep 21, 2015 License: Apache-2.0 Imports: 29 Imported by: 0

Documentation

Overview

Package client provides clients for accessing the various externally-facing Cockroach database endpoints.

DB Client

The DB client is a fully-featured client of Cockroach's key-value database. It provides a simple, synchronous interface well-suited to parallel updates and queries.

The simplest way to use the client is through the Run method. Run synchronously invokes the call, fills in the the reply and returns an error. The example below shows a get and a put. 

db, err := client.Open("rpcs://root@localhost:8080")
if err != nil {
	log.Fatal(err)
}
if err := db.Put("a", "hello"); err != nil {
	log.Fatal(err)
}
if gr, err := db.Get("a"); err != nil {
	log.Fatal(err)
} else {
	log.Printf("%s", gr.ValueBytes())  // "hello"
}

The API is synchronous, but accommodates efficient parallel updates and queries using Batch objects. An arbitrary number of calls may be added to a Batch which is executed using DB.Run. Note however that the individual calls within a batch are not guaranteed to have atomic semantics. A transaction must be used to guarantee atomicity. A simple example of using a Batch which does two scans in parallel and then sends a sequence of puts in parallel: 

db, err := client.Open("rpcs://root@localhost:8080")
if err != nil {
	log.Fatal(err)
}

b1 := &client.Batch{}
b1.Scan("a", "c\x00", 1000)
b1.Scan("x", "z\x00", 1000)

// Run sends both scans in parallel and returns the first error or nil.
if err := db.Run(b1); err != nil {
	log.Fatal(err)
}

acResult := b1.Results[0]
xzResult := b1.Results[1]

// Append maximum value from "a"-"c" to all values from "x"-"z".
max := []byte(nil)
for _, row := range acResult.Rows {
	if bytes.Compare(max, row.ValueBytes()) < 0 {
		max = row.ValueBytes()
	}
}

b2 := &client.Batch{}
for _, row := range xzResult.Rows {
	b2.Put(row.Key, bytes.Join([][]byte{row.ValueBytes(), max}, []byte(nil)))
}

// Run all puts for parallel execution.
if err := db.Run(b2); err != nil {
	log.Fatal(err)
}

Transactions are supported through the DB.Txn() method, which takes a retryable function, itself composed of the same simple mix of API calls typical of a non-transactional operation. Within the context of the Txn() call, all method invocations are transparently given necessary transactional details, and conflicts are handled with backoff/retry loops and transaction restarts as necessary. An example of using transactions with parallel writes: 

db, err := client.Open("rpcs://root@localhost:8080")
if err != nil {
	log.Fatal(err)
}

err := db.Txn(func(txn *client.Txn) error {
	b := &client.Batch{}
	for i := 0; i < 100; i++ {
		key := fmt.Sprintf("testkey-%02d", i)
		b.Put(key, "test value")
	}

	// Note that the Txn client is flushed automatically when this function
	// returns success (i.e. nil). Calling CommitInBatch explicitly can
	// sometimes reduce the number of RPCs.
	return txn.CommitInBatch(b)
})
if err != nil {
	log.Fatal(err)
}

Note that with Cockroach's lock-free transactions, clients should expect retries as a matter of course. This is why the transaction functionality is exposed through a retryable function. The retryable function should have no side effects which are not idempotent.

Transactions should endeavor to use batches to perform multiple operations in a single RPC. In addition to the reduced number of RPCs to the server, this allows writes to the same range to be batched together. In cases where the entire transaction affects only a single range, transactions can commit in a single round trip.

Index

Examples

Constants

View Source 
const (

	// Quit only handles Get requests.
	Quit = "quit"
)

Variables

View Source 
var DefaultTxnRetryOptions = retry.Options{
	InitialBackoff: 50 * time.Millisecond,
	MaxBackoff:     5 * time.Second,
	Multiplier:     2,
}

DefaultTxnRetryOptions are the standard retry options used for transactions. This is exported for testing purposes only.

Functions

func MaybeWrap 

func MaybeWrap(args proto.Request) (*proto.BatchRequest, func(proto.Response) proto.Response)

MaybeWrap wraps the given argument in a batch, unless it is already one. TODO(tschottdorf): will go when proto.Call does.

func MaybeWrapCall 

func MaybeWrapCall(call proto.Call) (proto.Call, func(proto.Call) proto.Call)

MaybeWrapCall returns a new call which wraps the original Args and Reply in a batch, if necessary. TODO(tschottdorf): will go when proto.Call does.

func RegisterSender 

func RegisterSender(scheme string, f NewSenderFunc)

RegisterSender registers the specified function to be used for creation of a new sender when the specified scheme is encountered.

func SendCallConverted 

func SendCallConverted(sender BatchSender, ctx context.Context, call proto.Call)

SendCallConverted is a wrapped to go from the (ctx,call) interface to the one used by batch.Sender. TODO(tschottdorf): remove when new proto.Call is gone.

Types

type AdminClient 

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

AdminClient issues http requests to admin endpoints. TODO(marc): unify the way we handle addresses in clients.

func NewAdminClient 

func NewAdminClient(ctx *base.Context, address, configType string) AdminClient

NewAdminClient returns a new 'configType' admin client, talking to 'address'.

func (*AdminClient) Delete 

func (a *AdminClient) Delete(key string) error

Delete issues a DELETE request for the given key.

func (*AdminClient) Get 

func (a *AdminClient) Get() (string, error)

Get issues a GET and returns the plain-text body. It cannot take a key.

func (*AdminClient) GetJSON 

func (a *AdminClient) GetJSON(key string) (string, error)

GetJSON issues a GET request and returns a json-encoded response.

func (*AdminClient) GetYAML 

func (a *AdminClient) GetYAML(key string) (string, error)

GetYAML issues a GET request and returns a yaml-encoded response.

func (*AdminClient) List 

func (a *AdminClient) List() ([]string, error)

List issues a GET request to list all configs. Returns a list of keys.

func (*AdminClient) SetJSON 

func (a *AdminClient) SetJSON(key, body string) error

SetJSON issues a POST request for the given key using the json-encoded body.

func (*AdminClient) SetYAML 

func (a *AdminClient) SetYAML(key, body string) error

SetYAML issues a POST request for the given key using the yaml-encoded body.

type Batch 

type Batch struct {
	// The DB the batch is associated with. This field may be nil if the batch
	// was not created via DB.NewBatch or Txn.NewBatch.
	DB *DB
	// Results contains an entry for each operation added to the batch. The order
	// of the results matches the order the operations were added to the
	// batch. For example:
	//
	//   b := db.NewBatch()
	//   b.Put("a", "1")
	//   b.Put("b", "2")
	//   _ = db.Run(b)
	//   // string(b.Results[0].Rows[0].Key) == "a"
	//   // string(b.Results[1].Rows[0].Key) == "b"
	Results []Result
	// contains filtered or unexported fields
}

Batch provides for the parallel execution of a number of database operations. Operations are added to the Batch and then the Batch is executed via either DB.Run, Txn.Run or Txn.Commit.

TODO(pmattis): Allow a timestamp to be specified which is applied to all operations within the batch.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	b := &client.Batch{}
	b.Get("aa")
	b.Put("bb", "2")
	if err := db.Run(b); err != nil {
		panic(err)
	}
	for _, result := range b.Results {
		for _, row := range result.Rows {
			fmt.Printf("%s=%s\n", row.Key, row.ValueBytes())
		}
	}

}

Output:

aa=
bb=2

func (*Batch) CPut 

func (b *Batch) CPut(key, value, expValue interface{})

CPut conditionally sets the value for a key if the existing value is equal to expValue. To conditionally set a value only if there is no existing entry pass nil for expValue.

A new result will be appended to the batch which will contain a single row and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler. value can be any key type or a proto.Message.

func (*Batch) Del 

func (b *Batch) Del(keys ...interface{})

Del deletes one or more keys.

A new result will be appended to the batch and each key will have a corresponding row in the returned Result.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Batch) DelRange 

func (b *Batch) DelRange(s, e interface{})

DelRange deletes the rows between begin (inclusive) and end (exclusive).

A new result will be appended to the batch which will contain 0 rows and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Batch) Get 

func (b *Batch) Get(key interface{})

Get retrieves the value for a key. A new result will be appended to the batch which will contain a single row. 

r, err := db.Get("a")
// string(r.Rows[0].Key) == "a"

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Batch) GetProto 

func (b *Batch) GetProto(key interface{}, msg gogoproto.Message)

GetProto retrieves the value for a key and decodes the result as a proto message. A new result will be appended to the batch which will contain a single row. Note that the proto will not be decoded until after the batch is executed using DB.Run or Txn.Run.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Batch) Inc 

func (b *Batch) Inc(key interface{}, value int64)

Inc increments the integer value at key. If the key does not exist it will be created with an initial value of 0 which will then be incremented. If the key exists but was set using Put or CPut an error will be returned.

A new result will be appended to the batch which will contain a single row and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Batch) InternalAddCall 

func (b *Batch) InternalAddCall(call proto.Call)

InternalAddCall adds the specified call to the batch. It is intended for internal use only.

func (*Batch) Put 

func (b *Batch) Put(key, value interface{})

Put sets the value for a key.

A new result will be appended to the batch which will contain a single row and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler. value can be any key type or a proto.Message.

func (*Batch) ReverseScan 

func (b *Batch) ReverseScan(s, e interface{}, maxRows int64)

ReverseScan retrieves the rows between begin (inclusive) and end (exclusive) in descending order.

A new result will be appended to the batch which will contain up to maxRows rows and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Batch) Scan 

func (b *Batch) Scan(s, e interface{}, maxRows int64)

Scan retrieves the rows between begin (inclusive) and end (exclusive) in ascending order.

A new result will be appended to the batch which will contain up to maxRows rows and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

type BatchSender 

type BatchSender interface {
	SendBatch(context.Context, proto.BatchRequest) (*proto.BatchResponse, error)
}

BatchSender is a new incarnation of client.Sender which only supports batches and uses a request-response pattern. TODO(tschottdorf): do away with client.Sender. TODO(tschottdorf) s/Batch// when client.Sender is out of the way.

type DB 

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

DB is a database handle to a single cockroach cluster. A DB is safe for concurrent use by multiple goroutines.

func NewDB 

func NewDB(sender Sender) *DB

NewDB returns a new DB.

func NewDBWithPriority 

func NewDBWithPriority(sender Sender, userPriority int32) *DB

NewDBWithPriority returns a new DB.

func Open 

func Open(stopper *stop.Stopper, addr string) (*DB, error)

Open creates a new database handle to the cockroach cluster specified by addr. The cluster is identified by a URL with the format: 

[<sender>:]//[<user>@]<host>:<port>[?certs=<dir>,priority=<val>]

The URL scheme (<sender>) specifies which transport to use for talking to the cockroach cluster. Currently allowable values are: http, https, rpc, rpcs. The rpc and rpcs senders use a variant of Go's builtin rpc library for communication with the cluster. This protocol is lower overhead and more efficient than http. The decision between the encrypted (https, rpcs) and unencrypted senders (http, rpc) depends on the settings of the cluster. A given cluster supports either encrypted or unencrypted traffic, but not both.

If not specified, the <user> field defaults to "root".

The certs parameter can be used to override the default directory to use for client certificates. In tests, the directory "test_certs" uses the embedded test certificates.

The priority parameter can be used to override the default priority for operations.

func (*DB) AdminMerge 

func (db *DB) AdminMerge(key interface{}) error

AdminMerge merges the range containing key and the subsequent range. After the merge operation is complete, the range containing key will contain all of the key/value pairs of the subsequent range and the subsequent range will no longer exist.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*DB) AdminSplit 

func (db *DB) AdminSplit(splitKey interface{}) error

AdminSplit splits the range at splitkey.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*DB) CPut 

func (db *DB) CPut(key, value, expValue interface{}) error

CPut conditionally sets the value for a key if the existing value is equal to expValue. To conditionally set a value only if there is no existing entry pass nil for expValue.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler. value can be any key type or a proto.Message.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	if err := db.Put("aa", "1"); err != nil {
		panic(err)
	}
	if err := db.CPut("aa", "2", "1"); err != nil {
		panic(err)
	}
	result, err := db.Get("aa")
	if err != nil {
		panic(err)
	}
	fmt.Printf("aa=%s\n", result.ValueBytes())

	if err = db.CPut("aa", "3", "1"); err == nil {
		panic("expected error from conditional put")
	}
	result, err = db.Get("aa")
	if err != nil {
		panic(err)
	}
	fmt.Printf("aa=%s\n", result.ValueBytes())

	if err = db.CPut("bb", "4", "1"); err == nil {
		panic("expected error from conditional put")
	}
	result, err = db.Get("bb")
	if err != nil {
		panic(err)
	}
	fmt.Printf("bb=%s\n", result.ValueBytes())
	if err = db.CPut("bb", "4", nil); err != nil {
		panic(err)
	}
	result, err = db.Get("bb")
	if err != nil {
		panic(err)
	}
	fmt.Printf("bb=%s\n", result.ValueBytes())

}

Output:

aa=2
aa=2
bb=
bb=4

func (*DB) Del 

func (db *DB) Del(keys ...interface{}) error

Del deletes one or more keys.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	b := &client.Batch{}
	b.Put("aa", "1")
	b.Put("ab", "2")
	b.Put("ac", "3")
	if err := db.Run(b); err != nil {
		panic(err)
	}
	if err := db.Del("ab"); err != nil {
		panic(err)
	}
	rows, err := db.Scan("a", "b", 100)
	if err != nil {
		panic(err)
	}
	for i, row := range rows {
		fmt.Printf("%d: %s=%s\n", i, row.Key, row.ValueBytes())
	}

}

Output:

0: aa=1
1: ac=3

func (*DB) DelRange 

func (db *DB) DelRange(begin, end interface{}) error

DelRange deletes the rows between begin (inclusive) and end (exclusive).

TODO(pmattis): Perhaps the result should return which rows were deleted.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*DB) Get 

func (db *DB) Get(key interface{}) (KeyValue, error)

Get retrieves the value for a key, returning the retrieved key/value or an error. 

r, err := db.Get("a")
// string(r.Key) == "a"

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	result, err := db.Get("aa")
	if err != nil {
		panic(err)
	}
	fmt.Printf("aa=%s\n", result.ValueBytes())

}

Output:

aa=

func (*DB) GetProto 

func (db *DB) GetProto(key interface{}, msg gogoproto.Message) error

GetProto retrieves the value for a key and decodes the result as a proto message.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*DB) GetSender 

func (db *DB) GetSender() Sender

GetSender returns the underlying Sender. Only exported for tests.

func (*DB) Inc 

func (db *DB) Inc(key interface{}, value int64) (KeyValue, error)

Inc increments the integer value at key. If the key does not exist it will be created with an initial value of 0 which will then be incremented. If the key exists but was set using Put or CPut an error will be returned.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	if _, err := db.Inc("aa", 100); err != nil {
		panic(err)
	}
	result, err := db.Get("aa")
	if err != nil {
		panic(err)
	}
	fmt.Printf("aa=%d\n", result.ValueInt())

}

Output:

aa=100

func (*DB) NewBatch 

func (db *DB) NewBatch() *Batch

NewBatch creates and returns a new empty batch object for use with the DB. TODO(tschottdorf): it appears this can be unexported.

func (*DB) Put 

func (db *DB) Put(key, value interface{}) error

Put sets the value for a key.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler. value can be any key type or a proto.Message.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	if err := db.Put("aa", "1"); err != nil {
		panic(err)
	}
	result, err := db.Get("aa")
	if err != nil {
		panic(err)
	}
	fmt.Printf("aa=%s\n", result.ValueBytes())

}

Output:

aa=1

func (*DB) ReverseScan 

func (db *DB) ReverseScan(begin, end interface{}, maxRows int64) ([]KeyValue, error)

ReverseScan retrieves the rows between begin (inclusive) and end (exclusive) in descending order.

The returned []KeyValue will contain up to maxRows elements.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	b := &client.Batch{}
	b.Put("aa", "1")
	b.Put("ab", "2")
	b.Put("bb", "3")
	if err := db.Run(b); err != nil {
		panic(err)
	}
	rows, err := db.ReverseScan("ab", "c", 100)
	if err != nil {
		panic(err)
	}
	for i, row := range rows {
		fmt.Printf("%d: %s=%s\n", i, row.Key, row.ValueBytes())
	}

}

Output:

0: bb=3
1: ab=2

func (*DB) Run 

func (db *DB) Run(b *Batch) error

Run executes the operations queued up within a batch. Before executing any of the operations the batch is first checked to see if there were any errors during its construction (e.g. failure to marshal a proto message).

The operations within a batch are run in parallel and the order is non-deterministic. It is an unspecified behavior to modify and retrieve the same key within a batch.

Upon completion, Batch.Results will contain the results for each operation. The order of the results matches the order the operations were added to the batch.

func (*DB) Scan 

func (db *DB) Scan(begin, end interface{}, maxRows int64) ([]KeyValue, error)

Scan retrieves the rows between begin (inclusive) and end (exclusive) in ascending order.

The returned []KeyValue will contain up to maxRows elements.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

Example 
package main

import (
	"fmt"

	"github.com/cockroachdb/cockroach/client"
	"github.com/cockroachdb/cockroach/security"
	"github.com/cockroachdb/cockroach/server"
	"github.com/cockroachdb/cockroach/util/log"
)

func setup() (*server.TestServer, *client.DB) {
	s := server.StartTestServer(nil)
	db, err := client.Open(s.Stopper(), fmt.Sprintf("rpcs://%s@%s?certs=test_certs",
		security.NodeUser,
		s.ServingAddr()))
	if err != nil {
		log.Fatal(err)
	}
	return s, db
}

func main() {
	s, db := setup()
	defer s.Stop()

	b := &client.Batch{}
	b.Put("aa", "1")
	b.Put("ab", "2")
	b.Put("bb", "3")
	if err := db.Run(b); err != nil {
		panic(err)
	}
	rows, err := db.Scan("a", "b", 100)
	if err != nil {
		panic(err)
	}
	for i, row := range rows {
		fmt.Printf("%d: %s=%s\n", i, row.Key, row.ValueBytes())
	}

}

Output:

0: aa=1
1: ab=2

func (*DB) Txn 

func (db *DB) Txn(retryable func(txn *Txn) error) error

Txn executes retryable in the context of a distributed transaction. The transaction is automatically aborted if retryable returns any error aside from recoverable internal errors, and is automatically committed otherwise. The retryable function should have no side effects which could cause problems in the event it must be run more than once.

TODO(pmattis): Allow transaction options to be specified.

type KeyValue 

type KeyValue struct {
	Key       []byte
	Value     interface{}
	Timestamp time.Time
}

KeyValue represents a single key/value pair and corresponding timestamp.

func (*KeyValue) Exists 

func (kv *KeyValue) Exists() bool

Exists returns true iff the value exists.

func (*KeyValue) String 

func (kv *KeyValue) String() string

func (*KeyValue) ValueBytes 

func (kv *KeyValue) ValueBytes() []byte

ValueBytes returns the value as a byte slice. This method will panic if the value's type is not a byte slice.

func (*KeyValue) ValueInt 

func (kv *KeyValue) ValueInt() int64

ValueInt returns the value decoded as an int64. This method will panic if the value cannot be decoded as an int64.

func (*KeyValue) ValueProto 

func (kv *KeyValue) ValueProto(msg gogoproto.Message) error

ValueProto parses the byte slice value as a proto message.

type NewSenderFunc 

type NewSenderFunc func(u *url.URL, ctx *base.Context, retryOpts retry.Options, stopper *stop.Stopper) (Sender, error)

NewSenderFunc creates a new sender for the registered scheme.

type Result 

type Result struct {

	// Err contains any error encountered when performing the operation.
	Err error
	// Rows contains the key/value pairs for the operation. The number of rows
	// returned varies by operation. For Get, Put, CPut, Inc and Del the number
	// of rows returned is the number of keys operated on. For Scan the number of
	// rows returned is the number or rows matching the scan capped by the
	// maxRows parameter. For DelRange Rows is nil.
	Rows []KeyValue
	// contains filtered or unexported fields
}

Result holds the result for a single DB or Txn operation (e.g. Get, Put, etc).

func (Result) String 

func (r Result) String() string

type Runner 

type Runner interface {
	Run(b *Batch) error
}

Runner only exports the Run method on a batch of operations.

type Sender 

type Sender interface {
	// Send invokes the Call.Method with Call.Args and sets the result
	// in Call.Reply.
	Send(context.Context, proto.Call)
}

Sender is an interface for sending a request to a Key-Value database backend.

type SenderFunc 

type SenderFunc func(context.Context, proto.Call)

SenderFunc is an adapter to allow the use of ordinary functions as Senders.

func (SenderFunc) Send 

func (f SenderFunc) Send(ctx context.Context, c proto.Call)

Send calls f(ctx, c).

type Txn 

type Txn struct {
	Proto proto.Transaction
	// contains filtered or unexported fields
}

Txn is an in-progress distributed database transaction. A Txn is not safe for concurrent use by multiple goroutines.

func NewTxn 

func NewTxn(db DB) *Txn

NewTxn returns a new txn.

func (*Txn) CPut 

func (txn *Txn) CPut(key, value, expValue interface{}) error

CPut conditionally sets the value for a key if the existing value is equal to expValue. To conditionally set a value only if there is no existing entry pass nil for expValue.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler. value can be any key type or a proto.Message.

func (*Txn) Cleanup 

func (txn *Txn) Cleanup(err error)

Cleanup cleans up the transaction as appropriate based on err.

func (*Txn) Commit 

func (txn *Txn) Commit() error

Commit sends an EndTransactionRequest with Commit=true.

func (*Txn) CommitInBatch 

func (txn *Txn) CommitInBatch(b *Batch) error

CommitInBatch executes the operations queued up within a batch and commits the transaction. Explicitly committing a transaction is optional, but more efficient than relying on the implicit commit performed when the transaction function returns without error.

func (*Txn) CommitNoCleanup 

func (txn *Txn) CommitNoCleanup() error

CommitNoCleanup is the same as Commit but will not attempt to clean up on failure. It is exposed only for use in txn_correctness_test.go because those tests manipulate transaction state at a low level.

func (*Txn) DebugName 

func (txn *Txn) DebugName() string

DebugName returns the debug name associated with the transaction.

func (*Txn) Del 

func (txn *Txn) Del(keys ...interface{}) error

Del deletes one or more keys.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) DelRange 

func (txn *Txn) DelRange(begin, end interface{}) error

DelRange deletes the rows between begin (inclusive) and end (exclusive).

The returned Result will contain 0 rows and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) Get 

func (txn *Txn) Get(key interface{}) (KeyValue, error)

Get retrieves the value for a key, returning the retrieved key/value or an error. 

r, err := db.Get("a")
// string(r.Key) == "a"

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) GetProto 

func (txn *Txn) GetProto(key interface{}, msg gogoproto.Message) error

GetProto retrieves the value for a key and decodes the result as a proto message.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) Inc 

func (txn *Txn) Inc(key interface{}, value int64) (KeyValue, error)

Inc increments the integer value at key. If the key does not exist it will be created with an initial value of 0 which will then be incremented. If the key exists but was set using Put or CPut an error will be returned.

The returned Result will contain a single row and Result.Err will indicate success or failure.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) InternalSetPriority 

func (txn *Txn) InternalSetPriority(priority int32)

InternalSetPriority sets the transaction priority. It is intended for internal (testing) use only.

func (*Txn) NewBatch 

func (txn *Txn) NewBatch() *Batch

NewBatch creates and returns a new empty batch object for use with the Txn.

func (*Txn) Put 

func (txn *Txn) Put(key, value interface{}) error

Put sets the value for a key

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler. value can be any key type or a proto.Message.

func (*Txn) ReverseScan 

func (txn *Txn) ReverseScan(begin, end interface{}, maxRows int64) ([]KeyValue, error)

ReverseScan retrieves the rows between begin (inclusive) and end (exclusive) in descending order.

The returned []KeyValue will contain up to maxRows elements.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) Rollback 

func (txn *Txn) Rollback() error

Rollback sends an EndTransactionRequest with Commit=false.

func (*Txn) Run 

func (txn *Txn) Run(b *Batch) error

Run executes the operations queued up within a batch. Before executing any of the operations the batch is first checked to see if there were any errors during its construction (e.g. failure to marshal a proto message).

The operations within a batch are run in parallel and the order is non-deterministic. It is an unspecified behavior to modify and retrieve the same key within a batch.

Upon completion, Batch.Results will contain the results for each operation. The order of the results matches the order the operations were added to the batch.

func (*Txn) Scan 

func (txn *Txn) Scan(begin, end interface{}, maxRows int64) ([]KeyValue, error)

Scan retrieves the rows between begin (inclusive) and end (exclusive) in ascending order.

The returned []KeyValue will contain up to maxRows elements.

key can be either a byte slice, a string, a fmt.Stringer or an encoding.BinaryMarshaler.

func (*Txn) SetDebugName 

func (txn *Txn) SetDebugName(name string, depth int)

SetDebugName sets the debug name associated with the transaction which will appear in log files and the web UI. Each transaction starts out with an automatically assigned debug name composed of the file and line number where the transaction was created.

func (*Txn) SetIsolation 

func (txn *Txn) SetIsolation(isolation proto.IsolationType) error

SetIsolation sets the transaction's isolation type. Transactions default to serializable isolation. The isolation must be set before any operations are performed on the transaction.

func (*Txn) SetSystemDBTrigger 

func (txn *Txn) SetSystemDBTrigger()

SetSystemDBTrigger sets the system db trigger to true on this transaction. This will impact the EndTransactionRequest.

func (*Txn) SystemDBTrigger 

func (txn *Txn) SystemDBTrigger() bool

SystemDBTrigger returns the systemDBTrigger flag.

Source Files

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