client.go

// Copyright 2014-2021 Aerospike, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package aerospike

import (
	"bytes"
	"context"
	"encoding/base64"
	"encoding/json"
	"errors"
	"fmt"
	"io/ioutil"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"golang.org/x/sync/semaphore"

	. "github.com/aerospike/aerospike-client-go/internal/atomic"
	. "github.com/aerospike/aerospike-client-go/logger"
	. "github.com/aerospike/aerospike-client-go/types"
)

// Client encapsulates an Aerospike cluster.
// All database operations are available against this object.
type Client struct {
	cluster *Cluster

	// DefaultPolicy is used for all read commands without a specific policy.
	DefaultPolicy *BasePolicy
	// DefaultBatchPolicy is used for all batch commands without a specific policy.
	DefaultBatchPolicy *BatchPolicy
	// DefaultWritePolicy is used for all write commands without a specific policy.
	DefaultWritePolicy *WritePolicy
	// DefaultScanPolicy is used for all scan commands without a specific policy.
	DefaultScanPolicy *ScanPolicy
	// DefaultQueryPolicy is used for all query commands without a specific policy.
	DefaultQueryPolicy *QueryPolicy
	// DefaultAdminPolicy is used for all security commands without a specific policy.
	DefaultAdminPolicy *AdminPolicy
	// DefaultInfoPolicy is used for all info commands without a specific policy.
	DefaultInfoPolicy *InfoPolicy
}

func clientFinalizer(f *Client) {
	f.Close()
}

//-------------------------------------------------------
// Constructors
//-------------------------------------------------------

// NewClient generates a new Client instance.
func NewClient(hostname string, port int) (*Client, error) {
	return NewClientWithPolicyAndHost(NewClientPolicy(), NewHost(hostname, port))
}

// NewClientWithPolicy generates a new Client using the specified ClientPolicy.
// If the policy is nil, the default relevant policy will be used.
func NewClientWithPolicy(policy *ClientPolicy, hostname string, port int) (*Client, error) {
	return NewClientWithPolicyAndHost(policy, NewHost(hostname, port))
}

// NewClientWithPolicyAndHost generates a new Client the specified ClientPolicy and
// sets up the cluster using the provided hosts.
// If the policy is nil, the default relevant policy will be used.
func NewClientWithPolicyAndHost(policy *ClientPolicy, hosts ...*Host) (*Client, error) {
	if policy == nil {
		policy = NewClientPolicy()
	}

	cluster, err := NewCluster(policy, hosts)
	if err != nil && policy.FailIfNotConnected {
		if aerr, ok := err.(AerospikeError); ok {
			Logger.Debug("Failed to connect to host(s): %v; error: %s", hosts, err)
			return nil, aerr
		}
		return nil, fmt.Errorf("Failed to connect to host(s): %v; error: %s", hosts, err)
	}

	client := &Client{
		cluster:            cluster,
		DefaultPolicy:      NewPolicy(),
		DefaultBatchPolicy: NewBatchPolicy(),
		DefaultWritePolicy: NewWritePolicy(0, 0),
		DefaultScanPolicy:  NewScanPolicy(),
		DefaultQueryPolicy: NewQueryPolicy(),
		DefaultAdminPolicy: NewAdminPolicy(),
	}

	runtime.SetFinalizer(client, clientFinalizer)
	return client, err

}

//-------------------------------------------------------
// Cluster Connection Management
//-------------------------------------------------------

// Close closes all client connections to database server nodes.
func (clnt *Client) Close() {
	clnt.cluster.Close()
}

// IsConnected determines if the client is ready to talk to the database server cluster.
func (clnt *Client) IsConnected() bool {
	return clnt.cluster.IsConnected()
}

// GetNodes returns an array of active server nodes in the cluster.
func (clnt *Client) GetNodes() []*Node {
	return clnt.cluster.GetNodes()
}

// GetNodeNames returns a list of active server node names in the cluster.
func (clnt *Client) GetNodeNames() []string {
	nodes := clnt.cluster.GetNodes()
	names := make([]string, 0, len(nodes))

	for _, node := range nodes {
		names = append(names, node.GetName())
	}
	return names
}

//-------------------------------------------------------
// Write Record Operations
//-------------------------------------------------------

// Put writes record bin(s) to the server.
// The policy specifies the transaction timeout, record expiration and how the transaction is
// handled when the record already exists.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Put(policy *WritePolicy, key *Key, binMap BinMap) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, nil, binMap, _WRITE)
	if err != nil {
		return err
	}

	return command.Execute()
}

// PutBins writes record bin(s) to the server.
// The policy specifies the transaction timeout, record expiration and how the transaction is
// handled when the record already exists.
// This method avoids using the BinMap allocation and iteration and is lighter on GC.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) PutBins(policy *WritePolicy, key *Key, bins ...*Bin) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, bins, nil, _WRITE)
	if err != nil {
		return err
	}

	return command.Execute()
}

//-------------------------------------------------------
// Operations string
//-------------------------------------------------------

// Append appends bin value's string to existing record bin values.
// The policy specifies the transaction timeout, record expiration and how the transaction is
// handled when the record already exists.
// This call only works for string and []byte values.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Append(policy *WritePolicy, key *Key, binMap BinMap) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, nil, binMap, _APPEND)
	if err != nil {
		return err
	}

	return command.Execute()
}

// AppendBins works the same as Append, but avoids BinMap allocation and iteration.
func (clnt *Client) AppendBins(policy *WritePolicy, key *Key, bins ...*Bin) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, bins, nil, _APPEND)
	if err != nil {
		return err
	}

	return command.Execute()
}

// Prepend prepends bin value's string to existing record bin values.
// The policy specifies the transaction timeout, record expiration and how the transaction is
// handled when the record already exists.
// This call works only for string and []byte values.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Prepend(policy *WritePolicy, key *Key, binMap BinMap) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, nil, binMap, _PREPEND)
	if err != nil {
		return err
	}

	return command.Execute()
}

// PrependBins works the same as Prepend, but avoids BinMap allocation and iteration.
func (clnt *Client) PrependBins(policy *WritePolicy, key *Key, bins ...*Bin) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, bins, nil, _PREPEND)
	if err != nil {
		return err
	}

	return command.Execute()
}

//-------------------------------------------------------
// Arithmetic Operations
//-------------------------------------------------------

// Add adds integer bin values to existing record bin values.
// The policy specifies the transaction timeout, record expiration and how the transaction is
// handled when the record already exists.
// This call only works for integer values.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Add(policy *WritePolicy, key *Key, binMap BinMap) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, nil, binMap, _ADD)
	if err != nil {
		return err
	}

	return command.Execute()
}

// AddBins works the same as Add, but avoids BinMap allocation and iteration.
func (clnt *Client) AddBins(policy *WritePolicy, key *Key, bins ...*Bin) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newWriteCommand(clnt.cluster, policy, key, bins, nil, _ADD)
	if err != nil {
		return err
	}

	return command.Execute()
}

//-------------------------------------------------------
// Delete Operations
//-------------------------------------------------------

// Delete deletes a record for specified key.
// The policy specifies the transaction timeout.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Delete(policy *WritePolicy, key *Key) (bool, error) {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newDeleteCommand(clnt.cluster, policy, key)
	if err != nil {
		return false, err
	}

	err = command.Execute()
	return command.Existed(), err
}

//-------------------------------------------------------
// Touch Operations
//-------------------------------------------------------

// Touch updates a record's metadata.
// If the record exists, the record's TTL will be reset to the
// policy's expiration.
// If the record doesn't exist, it will return an error.
func (clnt *Client) Touch(policy *WritePolicy, key *Key) error {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newTouchCommand(clnt.cluster, policy, key)
	if err != nil {
		return err
	}

	return command.Execute()
}

//-------------------------------------------------------
// Existence-Check Operations
//-------------------------------------------------------

// Exists determine if a record key exists.
// The policy can be used to specify timeouts.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Exists(policy *BasePolicy, key *Key) (bool, error) {
	policy = clnt.getUsablePolicy(policy)
	command, err := newExistsCommand(clnt.cluster, policy, key)
	if err != nil {
		return false, err
	}

	err = command.Execute()
	return command.Exists(), err
}

// BatchExists determines if multiple record keys exist in one batch request.
// The returned boolean array is in positional order with the original key array order.
// The policy can be used to specify timeouts.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) BatchExists(policy *BatchPolicy, keys []*Key) ([]bool, error) {
	policy = clnt.getUsableBatchPolicy(policy)

	// same array can be used without synchronization;
	// when a key exists, the corresponding index will be marked true
	existsArray := make([]bool, len(keys))

	batchNodes, err := newBatchNodeList(clnt.cluster, policy, keys)
	if err != nil {
		return nil, err
	}

	// pass nil to make sure it will be cloned and prepared
	cmd := newBatchCommandExists(nil, nil, policy, keys, existsArray)
	err, filteredOut := clnt.batchExecute(policy, batchNodes, cmd)
	if err != nil {
		return nil, err
	}

	if filteredOut > 0 {
		err = ErrFilteredOut
	}

	return existsArray, err
}

//-------------------------------------------------------
// Read Record Operations
//-------------------------------------------------------

// Get reads a record header and bins for specified key.
// The policy can be used to specify timeouts.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Get(policy *BasePolicy, key *Key, binNames ...string) (*Record, error) {
	policy = clnt.getUsablePolicy(policy)

	command, err := newReadCommand(clnt.cluster, policy, key, binNames, nil)
	if err != nil {
		return nil, err
	}

	if err := command.Execute(); err != nil {
		return nil, err
	}
	return command.GetRecord(), nil
}

// GetHeader reads a record generation and expiration only for specified key.
// Bins are not read.
// The policy can be used to specify timeouts.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) GetHeader(policy *BasePolicy, key *Key) (*Record, error) {
	policy = clnt.getUsablePolicy(policy)

	command, err := newReadHeaderCommand(clnt.cluster, policy, key)
	if err != nil {
		return nil, err
	}

	if err := command.Execute(); err != nil {
		return nil, err
	}
	return command.GetRecord(), nil
}

//-------------------------------------------------------
// Batch Read Operations
//-------------------------------------------------------

// BatchGet reads multiple record headers and bins for specified keys in one batch request.
// The returned records are in positional order with the original key array order.
// If a key is not found, the positional record will be nil.
// The policy can be used to specify timeouts.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) BatchGet(policy *BatchPolicy, keys []*Key, binNames ...string) ([]*Record, error) {
	policy = clnt.getUsableBatchPolicy(policy)

	// same array can be used without synchronization;
	// when a key exists, the corresponding index will be set to record
	records := make([]*Record, len(keys))

	batchNodes, err := newBatchNodeList(clnt.cluster, policy, keys)
	if err != nil {
		return nil, err
	}

	cmd := newBatchCommandGet(nil, nil, policy, keys, binNames, records, _INFO1_READ)
	err, filteredOut := clnt.batchExecute(policy, batchNodes, cmd)
	if err != nil && !policy.AllowPartialResults {
		return nil, err
	}

	if filteredOut > 0 {
		if err == nil {
			err = ErrFilteredOut
		} else {
			mergeErrors([]error{err, ErrFilteredOut})
		}
	}

	return records, err
}

// BatchGetComplex reads multiple records for specified batch keys in one batch call.
// This method allows different namespaces/bins to be requested for each key in the batch.
// The returned records are located in the same list.
// If the BatchRead key field is not found, the corresponding record field will be null.
// The policy can be used to specify timeouts and maximum concurrent threads.
// This method requires Aerospike Server version >= 3.6.0.
func (clnt *Client) BatchGetComplex(policy *BatchPolicy, records []*BatchRead) error {
	policy = clnt.getUsableBatchPolicy(policy)

	cmd := newBatchIndexCommandGet(nil, policy, records)

	batchNodes, err := newBatchIndexNodeList(clnt.cluster, policy, records)
	if err != nil {
		return err
	}

	err, filteredOut := clnt.batchExecute(policy, batchNodes, cmd)
	if err != nil && !policy.AllowPartialResults {
		return err
	}

	if filteredOut > 0 {
		if err == nil {
			err = ErrFilteredOut
		} else {
			mergeErrors([]error{err, ErrFilteredOut})
		}
	}

	return err
}

// BatchGetHeader reads multiple record header data for specified keys in one batch request.
// The returned records are in positional order with the original key array order.
// If a key is not found, the positional record will be nil.
// The policy can be used to specify timeouts.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) BatchGetHeader(policy *BatchPolicy, keys []*Key) ([]*Record, error) {
	policy = clnt.getUsableBatchPolicy(policy)

	// same array can be used without synchronization;
	// when a key exists, the corresponding index will be set to record
	records := make([]*Record, len(keys))

	batchNodes, err := newBatchNodeList(clnt.cluster, policy, keys)
	if err != nil {
		return nil, err
	}

	cmd := newBatchCommandGet(nil, nil, policy, keys, nil, records, _INFO1_READ|_INFO1_NOBINDATA)
	err, filteredOut := clnt.batchExecute(policy, batchNodes, cmd)
	if err != nil && !policy.AllowPartialResults {
		return nil, err
	}

	if filteredOut > 0 {
		if err == nil {
			err = ErrFilteredOut
		} else {
			mergeErrors([]error{err, ErrFilteredOut})
		}
	}

	return records, err
}

//-------------------------------------------------------
// Generic Database Operations
//-------------------------------------------------------

// Operate performs multiple read/write operations on a single key in one batch request.
// An example would be to add an integer value to an existing record and then
// read the result, all in one database call.
//
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Operate(policy *WritePolicy, key *Key, operations ...*Operation) (*Record, error) {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newOperateCommand(clnt.cluster, policy, key, operations)
	if err != nil {
		return nil, err
	}

	if err := command.Execute(); err != nil {
		return nil, err
	}
	return command.GetRecord(), nil
}

//-------------------------------------------------------
// Scan Operations
//-------------------------------------------------------

// ScanPartitions Read records in specified namespace, set and partition filter.
// If the policy's concurrentNodes is specified, each server node will be read in
// parallel. Otherwise, server nodes are read sequentially.
// If partitionFilter is nil, all partitions will be scanned.
// If the policy is nil, the default relevant policy will be used.
// This method is only supported by Aerospike 4.9+ servers.
func (clnt *Client) ScanPartitions(apolicy *ScanPolicy, partitionFilter *PartitionFilter, namespace string, setName string, binNames ...string) (*Recordset, error) {
	if !clnt.cluster.supportsPartitionScans.Get() {
		return nil, ErrPartitionScanQueryNotSupported
	}

	policy := *clnt.getUsableScanPolicy(apolicy)

	nodes := clnt.cluster.GetNodes()
	if len(nodes) == 0 {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "Scan failed because cluster is empty.")
	}

	var tracker *partitionTracker
	if partitionFilter == nil {
		tracker = newPartitionTrackerForNodes(&policy.MultiPolicy, nodes)
	} else {
		tracker = newPartitionTracker(&policy.MultiPolicy, partitionFilter, nodes)
	}

	// result recordset
	res := newRecordset(policy.RecordQueueSize, 1)
	go clnt.scanPartitions(&policy, tracker, namespace, setName, res, binNames...)

	return res, nil
}

// ScanAll reads all records in specified namespace and set from all nodes.
// If the policy's concurrentNodes is specified, each server node will be read in
// parallel. Otherwise, server nodes are read sequentially.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) ScanAll(apolicy *ScanPolicy, namespace string, setName string, binNames ...string) (*Recordset, error) {
	if clnt.cluster.supportsPartitionScans.Get() {
		return clnt.ScanPartitions(apolicy, nil, namespace, setName, binNames...)
	}

	policy := *clnt.getUsableScanPolicy(apolicy)

	nodes := clnt.cluster.GetNodes()
	if len(nodes) == 0 {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "Scan failed because cluster is empty.")
	}

	clusterKey := int64(0)
	if policy.FailOnClusterChange {
		var err error
		clusterKey, err = queryValidateBegin(nodes[0], namespace)
		if err != nil {
			return nil, err
		}
	}

	first := NewAtomicBool(true)

	// result recordset
	res := newRecordset(policy.RecordQueueSize, len(nodes))

	// the whole call should be wrapped in a goroutine
	if policy.ConcurrentNodes && len(nodes) > 1 {
		maxConcurrentNodes := policy.MaxConcurrentNodes
		if maxConcurrentNodes <= 0 {
			maxConcurrentNodes = len(nodes)
		}
		sem := semaphore.NewWeighted(int64(maxConcurrentNodes))
		ctx := context.Background()
		for _, node := range nodes {
			if err := sem.Acquire(ctx, 1); err != nil {
				Logger.Error("Constraint Semaphore failed for Scan: %s", err.Error())
			}
			go func(node *Node, first bool) {
				defer sem.Release(1)
				clnt.scanNode(&policy, node, res, namespace, setName, clusterKey, first, binNames...)
			}(node, first.CompareAndToggle(true))
		}
	} else {
		// scan nodes one by one
		go func() {
			for _, node := range nodes {
				clnt.scanNode(&policy, node, res, namespace, setName, clusterKey, first.CompareAndToggle(true), binNames...)
			}
		}()
	}

	return res, nil
}

// scanNodePartitions reads all records in specified namespace and set for one node only.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) scanNodePartitions(apolicy *ScanPolicy, node *Node, namespace string, setName string, binNames ...string) (*Recordset, error) {
	policy := *clnt.getUsableScanPolicy(apolicy)

	tracker := newPartitionTrackerForNode(&policy.MultiPolicy, node)

	// result recordset
	res := newRecordset(policy.RecordQueueSize, 1)
	go clnt.scanPartitions(&policy, tracker, namespace, setName, res, binNames...)

	return res, nil
}

// ScanNode reads all records in specified namespace and set for one node only.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) ScanNode(apolicy *ScanPolicy, node *Node, namespace string, setName string, binNames ...string) (*Recordset, error) {
	if clnt.cluster.supportsPartitionScans.Get() {
		return clnt.scanNodePartitions(apolicy, node, namespace, setName, binNames...)
	}

	policy := *clnt.getUsableScanPolicy(apolicy)

	clusterKey := int64(0)
	if policy.FailOnClusterChange {
		var err error
		clusterKey, err = queryValidateBegin(node, namespace)
		if err != nil {
			return nil, err
		}
	}

	// results channel must be async for performance
	res := newRecordset(policy.RecordQueueSize, 1)

	go clnt.scanNode(&policy, node, res, namespace, setName, clusterKey, true, binNames...)
	return res, nil
}

// ScanNode reads all records in specified namespace and set for one node only.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) scanNode(policy *ScanPolicy, node *Node, recordset *Recordset, namespace string, setName string, clusterKey int64, first bool, binNames ...string) error {
	defer recordset.signalEnd()
	command := newScanCommand(node, policy, namespace, setName, binNames, recordset, clusterKey, first)
	return command.Execute()
}

//---------------------------------------------------------------
// User defined functions (Supported by Aerospike 3+ servers only)
//---------------------------------------------------------------

// RegisterUDFFromFile reads a file from file system and registers
// the containing a package user defined functions with the server.
// This asynchronous server call will return before command is complete.
// The user can optionally wait for command completion by using the returned
// RegisterTask instance.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) RegisterUDFFromFile(policy *WritePolicy, clientPath string, serverPath string, language Language) (*RegisterTask, error) {
	policy = clnt.getUsableWritePolicy(policy)
	udfBody, err := ioutil.ReadFile(clientPath)
	if err != nil {
		return nil, err
	}

	return clnt.RegisterUDF(policy, udfBody, serverPath, language)
}

// RegisterUDF registers a package containing user defined functions with server.
// This asynchronous server call will return before command is complete.
// The user can optionally wait for command completion by using the returned
// RegisterTask instance.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) RegisterUDF(policy *WritePolicy, udfBody []byte, serverPath string, language Language) (*RegisterTask, error) {
	policy = clnt.getUsableWritePolicy(policy)
	content := base64.StdEncoding.EncodeToString(udfBody)

	var strCmd bytes.Buffer
	// errors are to remove errcheck warnings
	// they will always be nil as stated in golang docs
	_, err := strCmd.WriteString("udf-put:filename=")
	_, err = strCmd.WriteString(serverPath)
	_, err = strCmd.WriteString(";content=")
	_, err = strCmd.WriteString(content)
	_, err = strCmd.WriteString(";content-len=")
	_, err = strCmd.WriteString(strconv.Itoa(len(content)))
	_, err = strCmd.WriteString(";udf-type=")
	_, err = strCmd.WriteString(string(language))
	_, err = strCmd.WriteString(";")

	// Send UDF to one node. That node will distribute the UDF to other nodes.
	responseMap, err := clnt.sendInfoCommand(policy.TotalTimeout, strCmd.String())
	if err != nil {
		return nil, err
	}

	response := responseMap[strCmd.String()]
	res := make(map[string]string)
	vals := strings.Split(response, ";")
	for _, pair := range vals {
		t := strings.SplitN(pair, "=", 2)
		if len(t) == 2 {
			res[t[0]] = t[1]
		} else if len(t) == 1 {
			res[t[0]] = ""
		}
	}

	if _, exists := res["error"]; exists {
		msg, _ := base64.StdEncoding.DecodeString(res["message"])
		return nil, NewAerospikeError(COMMAND_REJECTED, fmt.Sprintf("Registration failed: %s\nFile: %s\nLine: %s\nMessage: %s",
			res["error"], res["file"], res["line"], msg))
	}
	return NewRegisterTask(clnt.cluster, serverPath), nil
}

// RemoveUDF removes a package containing user defined functions in the server.
// This asynchronous server call will return before command is complete.
// The user can optionally wait for command completion by using the returned
// RemoveTask instance.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) RemoveUDF(policy *WritePolicy, udfName string) (*RemoveTask, error) {
	policy = clnt.getUsableWritePolicy(policy)
	var strCmd bytes.Buffer
	// errors are to remove errcheck warnings
	// they will always be nil as stated in golang docs
	_, err := strCmd.WriteString("udf-remove:filename=")
	_, err = strCmd.WriteString(udfName)
	_, err = strCmd.WriteString(";")

	// Send command to one node. That node will distribute it to other nodes.
	responseMap, err := clnt.sendInfoCommand(policy.TotalTimeout, strCmd.String())
	if err != nil {
		return nil, err
	}

	response := responseMap[strCmd.String()]
	if response == "ok" {
		return NewRemoveTask(clnt.cluster, udfName), nil
	}
	return nil, NewAerospikeError(SERVER_ERROR, response)
}

// ListUDF lists all packages containing user defined functions in the server.
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) ListUDF(policy *BasePolicy) ([]*UDF, error) {
	policy = clnt.getUsablePolicy(policy)

	var strCmd bytes.Buffer
	// errors are to remove errcheck warnings
	// they will always be nil as stated in golang docs
	_, err := strCmd.WriteString("udf-list")

	// Send command to one node. That node will distribute it to other nodes.
	responseMap, err := clnt.sendInfoCommand(policy.TotalTimeout, strCmd.String())
	if err != nil {
		return nil, err
	}

	response := responseMap[strCmd.String()]
	vals := strings.Split(response, ";")
	res := make([]*UDF, 0, len(vals))

	for _, udfInfo := range vals {
		if strings.Trim(udfInfo, " ") == "" {
			continue
		}
		udfParts := strings.Split(udfInfo, ",")

		udf := &UDF{}
		for _, values := range udfParts {
			valueParts := strings.Split(values, "=")
			if len(valueParts) == 2 {
				switch valueParts[0] {
				case "filename":
					udf.Filename = valueParts[1]
				case "hash":
					udf.Hash = valueParts[1]
				case "type":
					udf.Language = Language(valueParts[1])
				}
			}
		}
		res = append(res, udf)
	}

	return res, nil
}

// Execute executes a user defined function on server and return results.
// The function operates on a single record.
// The package name is used to locate the udf file location:
//
// udf file = <server udf dir>/<package name>.lua
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Execute(policy *WritePolicy, key *Key, packageName string, functionName string, args ...Value) (interface{}, error) {
	policy = clnt.getUsableWritePolicy(policy)
	command, err := newExecuteCommand(clnt.cluster, policy, key, packageName, functionName, NewValueArray(args))
	if err != nil {
		return nil, err
	}

	if err := command.Execute(); err != nil {
		return nil, err
	}

	record := command.GetRecord()

	if record == nil || len(record.Bins) == 0 {
		return nil, nil
	}

	for k, v := range record.Bins {
		if strings.Contains(k, "SUCCESS") {
			return v, nil
		} else if strings.Contains(k, "FAILURE") {
			return nil, fmt.Errorf("%v", v)
		}
	}

	return nil, ErrUDFBadResponse
}

//----------------------------------------------------------
// Query/Execute (Supported by Aerospike 3+ servers only)
//----------------------------------------------------------

// QueryExecute applies operations on records that match the statement filter.
// Records are not returned to the client.
// This asynchronous server call will return before the command is complete.
// The user can optionally wait for command completion by using the returned
// ExecuteTask instance.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) QueryExecute(policy *QueryPolicy,
	writePolicy *WritePolicy,
	statement *Statement,
	ops ...*Operation,
) (*ExecuteTask, error) {

	if len(ops) == 0 {
		return nil, ErrNoOperationsSpecified
	}

	if len(statement.BinNames) > 0 {
		return nil, ErrNoBinNamesAlloedInQueryExecute
	}

	policy = clnt.getUsableQueryPolicy(policy)
	writePolicy = clnt.getUsableWritePolicy(writePolicy)

	nodes := clnt.cluster.GetNodes()
	if len(nodes) == 0 {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "ExecuteOperations failed because cluster is empty.")
	}

	statement.prepare(false)

	errs := []error{}
	for i := range nodes {
		command := newServerCommand(nodes[i], policy, writePolicy, statement, statement.TaskId, ops)
		if err := command.Execute(); err != nil {
			errs = append(errs, err)
		}
	}

	return NewExecuteTask(clnt.cluster, statement), mergeErrors(errs)
}

// ExecuteUDF applies user defined function on records that match the statement filter.
// Records are not returned to the client.
// This asynchronous server call will return before command is complete.
// The user can optionally wait for command completion by using the returned
// ExecuteTask instance.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) ExecuteUDF(policy *QueryPolicy,
	statement *Statement,
	packageName string,
	functionName string,
	functionArgs ...Value,
) (*ExecuteTask, error) {
	policy = clnt.getUsableQueryPolicy(policy)

	nodes := clnt.cluster.GetNodes()
	if len(nodes) == 0 {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "ExecuteUDF failed because cluster is empty.")
	}

	statement.SetAggregateFunction(packageName, functionName, functionArgs, false)

	errs := []error{}
	for i := range nodes {
		command := newServerCommand(nodes[i], policy, nil, statement, statement.TaskId, nil)
		if err := command.Execute(); err != nil {
			errs = append(errs, err)
		}
	}

	return NewExecuteTask(clnt.cluster, statement), mergeErrors(errs)
}

// ExecuteUDFNode applies user defined function on records that match the statement filter on the specified node.
// Records are not returned to the client.
// This asynchronous server call will return before command is complete.
// The user can optionally wait for command completion by using the returned
// ExecuteTask instance.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) ExecuteUDFNode(policy *QueryPolicy,
	node *Node,
	statement *Statement,
	packageName string,
	functionName string,
	functionArgs ...Value,
) (*ExecuteTask, error) {
	policy = clnt.getUsableQueryPolicy(policy)

	if node == nil {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "ExecuteUDFNode failed because node is nil.")
	}

	statement.SetAggregateFunction(packageName, functionName, functionArgs, false)

	command := newServerCommand(node, policy, nil, statement, statement.TaskId, nil)
	err := command.Execute()

	return NewExecuteTask(clnt.cluster, statement), err
}

// SetXDRFilter sets XDR filter for given datacenter name and namespace. The expression filter indicates
// which records XDR should ship to the datacenter.
// Pass nil as filter to remove the currentl filter on the server.
func (clnt *Client) SetXDRFilter(policy *InfoPolicy, datacenter string, namespace string, filter *FilterExpression) error {
	policy = clnt.getUsableInfoPolicy(policy)

	var strCmd string
	if filter == nil {
		strCmd = "xdr-set-filter:dc=" + datacenter + ";namespace=" + namespace + ";exp=null"
	} else {
		b64, err := filter.base64()
		if err != nil {
			return NewAerospikeError(SERIALIZE_ERROR, "FilterExpression could not be serialized to Base64")
		}

		strCmd = "xdr-set-filter:dc=" + datacenter + ";namespace=" + namespace + ";exp=" + b64
	}

	// Send command to one node. That node will distribute it to other nodes.
	responseMap, err := clnt.sendInfoCommand(policy.Timeout, strCmd)
	if err != nil {
		return err
	}

	response := responseMap[strCmd]
	if strings.EqualFold(response, "ok") {
		return nil
	}

	code := parseIndexErrorCode(response)
	return NewAerospikeError(code, response)
}

func parseIndexErrorCode(response string) ResultCode {
	var code ResultCode = 0

	list := strings.Split(response, ":")
	if len(list) >= 2 && list[0] == "FAIL" {
		i, err := strconv.ParseInt(list[1], 10, 64)
		if err == nil {
			code = ResultCode(i)
		}
	}

	if code == 0 {
		code = SERVER_ERROR
	}

	return code
}

//--------------------------------------------------------
// Query functions (Supported by Aerospike 3+ servers only)
//--------------------------------------------------------

// QueryPartitions executes a query for specified partitions and returns a recordset.
// The query executor puts records on the channel from separate goroutines.
// The caller can concurrently pop records off the channel through the
// Recordset.Records channel.
//
// This method is only supported by Aerospike 4.9+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) QueryPartitions(policy *QueryPolicy, statement *Statement, partitionFilter *PartitionFilter) (*Recordset, error) {
	if statement.Filter != nil || !clnt.cluster.supportsPartitionScans.Get() {
		return nil, ErrPartitionScanQueryNotSupported
	}

	policy = clnt.getUsableQueryPolicy(policy)

	nodes := clnt.cluster.GetNodes()
	if len(nodes) == 0 {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "Query failed because cluster is empty.")
	}

	var tracker *partitionTracker

	if partitionFilter == nil {
		tracker = newPartitionTrackerForNodes(&policy.MultiPolicy, nodes)
	} else {
		tracker = newPartitionTracker(&policy.MultiPolicy, partitionFilter, nodes)
	}

	// result recordset
	res := newRecordset(policy.RecordQueueSize, 1)
	go clnt.queryPartitions(policy, tracker, statement, res)

	return res, nil
}

// Query executes a query and returns a Recordset.
// The query executor puts records on the channel from separate goroutines.
// The caller can concurrently pop records off the channel through the
// Recordset.Records channel.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) Query(policy *QueryPolicy, statement *Statement) (*Recordset, error) {
	if statement.Filter == nil && clnt.cluster.supportsPartitionScans.Get() {
		return clnt.QueryPartitions(policy, statement, nil)
	}

	policy = clnt.getUsableQueryPolicy(policy)

	nodes := clnt.cluster.GetNodes()
	if len(nodes) == 0 {
		return nil, NewAerospikeError(SERVER_NOT_AVAILABLE, "Query failed because cluster is empty.")
	}

	clusterKey := int64(0)
	if policy.FailOnClusterChange {
		var err error
		clusterKey, err = queryValidateBegin(nodes[0], statement.Namespace)
		if err != nil {
			return nil, err
		}
	}

	first := NewAtomicBool(true)

	// results channel must be async for performance
	recSet := newRecordset(policy.RecordQueueSize, len(nodes))

	// results channel must be async for performance
	maxConcurrentNodes := policy.MaxConcurrentNodes
	if maxConcurrentNodes <= 0 {
		maxConcurrentNodes = len(nodes)
	}
	sem := semaphore.NewWeighted(int64(maxConcurrentNodes))
	ctx := context.Background()
	for _, node := range nodes {
		if err := sem.Acquire(ctx, 1); err != nil {
			Logger.Error("Constraint Semaphore failed for Query: %s", err.Error())
		}
		go func(node *Node, first bool) {
			defer sem.Release(1)
			clnt.queryNode(node, policy, statement, recSet, clusterKey, first)
		}(node, first.CompareAndToggle(true))
	}

	return recSet, nil
}

// QueryNode executes a query on a specific node and returns a recordset.
// The caller can concurrently pop records off the channel through the
// record channel.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) QueryNode(policy *QueryPolicy, node *Node, statement *Statement) (*Recordset, error) {
	if statement.Filter == nil && clnt.cluster.supportsPartitionScans.Get() {
		return clnt.queryNodePartitions(policy, node, statement)
	}

	policy = clnt.getUsableQueryPolicy(policy)

	// results channel must be async for performance
	recSet := newRecordset(policy.RecordQueueSize, 1)

	clusterKey := int64(0)
	if policy.FailOnClusterChange {
		var err error
		clusterKey, err = queryValidateBegin(node, statement.Namespace)
		if err != nil {
			return nil, err
		}
	}

	// copy policies to avoid race conditions
	go clnt.queryNode(node, policy, statement, recSet, clusterKey, true)

	return recSet, nil
}

func (clnt *Client) queryNodePartitions(policy *QueryPolicy, node *Node, statement *Statement) (*Recordset, error) {
	policy = clnt.getUsableQueryPolicy(policy)

	tracker := newPartitionTrackerForNode(&policy.MultiPolicy, node)

	// result recordset
	res := newRecordset(policy.RecordQueueSize, 1)
	go clnt.queryPartitions(policy, tracker, statement, res)

	return res, nil
}

// queryNode executes a query on a specific node and returns a recordset.
// The caller can concurrently pop records off the channel through the
// record channel.
//
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) queryNode(node *Node, policy *QueryPolicy, statement *Statement, recordset *Recordset, clusterKey int64, first bool) error {
	defer recordset.signalEnd()

	// copy policies to avoid race conditions
	newPolicy := *policy
	command := newQueryRecordCommand(node, &newPolicy, statement, recordset, clusterKey, true)
	return command.Execute()
}

//--------------------------------------------------------
// Index functions (Supported by Aerospike 3+ servers only)
//--------------------------------------------------------

// CreateIndex creates a secondary index.
// This asynchronous server call will return before the command is complete.
// The user can optionally wait for command completion by using the returned
// IndexTask instance.
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) CreateIndex(
	policy *WritePolicy,
	namespace string,
	setName string,
	indexName string,
	binName string,
	indexType IndexType,
) (*IndexTask, error) {
	policy = clnt.getUsableWritePolicy(policy)
	return clnt.CreateComplexIndex(policy, namespace, setName, indexName, binName, indexType, ICT_DEFAULT)
}

// CreateComplexIndex creates a secondary index, with the ability to put indexes
// on bin containing complex data types, e.g: Maps and Lists.
// This asynchronous server call will return before the command is complete.
// The user can optionally wait for command completion by using the returned
// IndexTask instance.
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) CreateComplexIndex(
	policy *WritePolicy,
	namespace string,
	setName string,
	indexName string,
	binName string,
	indexType IndexType,
	indexCollectionType IndexCollectionType,
) (*IndexTask, error) {
	policy = clnt.getUsableWritePolicy(policy)

	var strCmd bytes.Buffer
	_, err := strCmd.WriteString("sindex-create:ns=")
	_, err = strCmd.WriteString(namespace)

	if len(setName) > 0 {
		_, err = strCmd.WriteString(";set=")
		_, err = strCmd.WriteString(setName)
	}

	_, err = strCmd.WriteString(";indexname=")
	_, err = strCmd.WriteString(indexName)
	_, err = strCmd.WriteString(";numbins=1")

	if indexCollectionType != ICT_DEFAULT {
		_, err = strCmd.WriteString(";indextype=")
		_, err = strCmd.WriteString(ictToString(indexCollectionType))
	}

	_, err = strCmd.WriteString(";indexdata=")
	_, err = strCmd.WriteString(binName)
	_, err = strCmd.WriteString(",")
	_, err = strCmd.WriteString(string(indexType))
	_, err = strCmd.WriteString(";priority=normal")

	// Send index command to one node. That node will distribute the command to other nodes.
	responseMap, err := clnt.sendInfoCommand(policy.TotalTimeout, strCmd.String())
	if err != nil {
		return nil, err
	}

	response := responseMap[strCmd.String()]
	if strings.EqualFold(response, "OK") {
		// Return task that could optionally be polled for completion.
		return NewIndexTask(clnt.cluster, namespace, indexName), nil
	}

	if strings.HasPrefix(response, "FAIL:200") {
		// Index has already been created.  Do not need to poll for completion.
		return nil, NewAerospikeError(INDEX_FOUND)
	}

	return nil, NewAerospikeError(INDEX_GENERIC, "Create index failed: "+response)
}

// DropIndex deletes a secondary index. It will block until index is dropped on all nodes.
// This method is only supported by Aerospike 3+ servers.
// If the policy is nil, the default relevant policy will be used.
func (clnt *Client) DropIndex(
	policy *WritePolicy,
	namespace string,
	setName string,
	indexName string,
) error {
	policy = clnt.getUsableWritePolicy(policy)
	var strCmd bytes.Buffer
	_, err := strCmd.WriteString("sindex-delete:ns=")
	_, err = strCmd.WriteString(namespace)

	if len(setName) > 0 {
		_, err = strCmd.WriteString(";set=")
		_, err = strCmd.WriteString(setName)
	}
	_, err = strCmd.WriteString(";indexname=")
	_, err = strCmd.WriteString(indexName)

	// Send index command to one node. That node will distribute the command to other nodes.
	responseMap, err := clnt.sendInfoCommand(policy.TotalTimeout, strCmd.String())
	if err != nil {
		return err
	}

	response := responseMap[strCmd.String()]

	if strings.EqualFold(response, "OK") {
		// Return task that could optionally be polled for completion.
		task := NewDropIndexTask(clnt.cluster, namespace, indexName)
		return <-task.OnComplete()
	}

	if strings.HasPrefix(response, "FAIL:201") {
		// Index did not previously exist. Return without error.
		return nil
	}

	return NewAerospikeError(INDEX_GENERIC, "Drop index failed: "+response)
}

// Truncate removes records in specified namespace/set efficiently.  This method is many orders of magnitude
// faster than deleting records one at a time.  Works with Aerospike Server versions >= 3.12.
// This asynchronous server call may return before the truncation is complete.  The user can still
// write new records after the server call returns because new records will have last update times
// greater than the truncate cutoff (set at the time of truncate call).
// For more information, See https://www.aerospike.com/docs/reference/info#truncate
func (clnt *Client) Truncate(policy *WritePolicy, namespace, set string, beforeLastUpdate *time.Time) error {
	policy = clnt.getUsableWritePolicy(policy)

	node, err := clnt.cluster.GetRandomNode()
	if err != nil {
		return err
	}

	node.tendConnLock.Lock()
	defer node.tendConnLock.Unlock()

	if err := node.initTendConn(policy.TotalTimeout); err != nil {
		return err
	}

	var strCmd bytes.Buffer
	if len(set) > 0 {
		_, err = strCmd.WriteString("truncate:namespace=")
		_, err = strCmd.WriteString(namespace)
		_, err = strCmd.WriteString(";set=")
		_, err = strCmd.WriteString(set)
	} else {
		// Servers >= 4.5.1.0 support truncate-namespace.
		if node.supportsTruncateNamespace.Get() {
			_, err = strCmd.WriteString("truncate-namespace:namespace=")
			_, err = strCmd.WriteString(namespace)
		} else {
			_, err = strCmd.WriteString("truncate:namespace=")
			_, err = strCmd.WriteString(namespace)
		}
	}
	if beforeLastUpdate != nil {
		_, err = strCmd.WriteString(";lut=")
		_, err = strCmd.WriteString(strconv.FormatInt(beforeLastUpdate.UnixNano(), 10))
	} else {
		// Servers >= 4.3.1.4 and <= 4.5.0.1 require lut argument.
		if node.supportsLUTNow.Get() {
			_, err = strCmd.WriteString(";lut=now")
		}
	}

	responseMap, err := RequestInfo(node.tendConn, strCmd.String())
	if err != nil {
		node.tendConn.Close()
		return err
	}

	response := responseMap[strCmd.String()]
	if strings.EqualFold(response, "OK") {
		return nil
	}

	return NewAerospikeError(SERVER_ERROR, "Truncate failed: "+response)
}

//-------------------------------------------------------
// User administration
//-------------------------------------------------------

// CreateUser creates a new user with password and roles. Clear-text password will be hashed using bcrypt
// before sending to server.
func (clnt *Client) CreateUser(policy *AdminPolicy, user string, password string, roles []string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	hash, err := hashPassword(password)
	if err != nil {
		return err
	}
	command := newAdminCommand(nil)
	return command.createUser(clnt.cluster, policy, user, hash, roles)
}

// DropUser removes a user from the cluster.
func (clnt *Client) DropUser(policy *AdminPolicy, user string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.dropUser(clnt.cluster, policy, user)
}

// ChangePassword changes a user's password. Clear-text password will be hashed using bcrypt before sending to server.
func (clnt *Client) ChangePassword(policy *AdminPolicy, user string, password string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	if clnt.cluster.user == "" {
		return NewAerospikeError(INVALID_USER)
	}

	hash, err := hashPassword(password)
	if err != nil {
		return err
	}
	command := newAdminCommand(nil)

	if user == clnt.cluster.user {
		// Change own password.
		if err := command.changePassword(clnt.cluster, policy, user, hash); err != nil {
			return err
		}
	} else {
		// Change other user's password by user admin.
		if err := command.setPassword(clnt.cluster, policy, user, hash); err != nil {
			return err
		}
	}

	clnt.cluster.changePassword(user, password, hash)

	return nil
}

// GrantRoles adds roles to user's list of roles.
func (clnt *Client) GrantRoles(policy *AdminPolicy, user string, roles []string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.grantRoles(clnt.cluster, policy, user, roles)
}

// RevokeRoles removes roles from user's list of roles.
func (clnt *Client) RevokeRoles(policy *AdminPolicy, user string, roles []string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.revokeRoles(clnt.cluster, policy, user, roles)
}

// QueryUser retrieves roles for a given user.
func (clnt *Client) QueryUser(policy *AdminPolicy, user string) (*UserRoles, error) {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.queryUser(clnt.cluster, policy, user)
}

// QueryUsers retrieves all users and their roles.
func (clnt *Client) QueryUsers(policy *AdminPolicy) ([]*UserRoles, error) {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.queryUsers(clnt.cluster, policy)
}

// QueryRole retrieves privileges for a given role.
func (clnt *Client) QueryRole(policy *AdminPolicy, role string) (*Role, error) {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.queryRole(clnt.cluster, policy, role)
}

// QueryRoles retrieves all roles and their privileges.
func (clnt *Client) QueryRoles(policy *AdminPolicy) ([]*Role, error) {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.queryRoles(clnt.cluster, policy)
}

// CreateRole creates a user-defined role.
func (clnt *Client) CreateRole(policy *AdminPolicy, roleName string, privileges []Privilege, whitelist []string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.createRole(clnt.cluster, policy, roleName, privileges, whitelist)
}

// DropRole removes a user-defined role.
func (clnt *Client) DropRole(policy *AdminPolicy, roleName string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.dropRole(clnt.cluster, policy, roleName)
}

// GrantPrivileges grant privileges to a user-defined role.
func (clnt *Client) GrantPrivileges(policy *AdminPolicy, roleName string, privileges []Privilege) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.grantPrivileges(clnt.cluster, policy, roleName, privileges)
}

// RevokePrivileges revokes privileges from a user-defined role.
func (clnt *Client) RevokePrivileges(policy *AdminPolicy, roleName string, privileges []Privilege) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.revokePrivileges(clnt.cluster, policy, roleName, privileges)
}

// SetWhitelist sets IP address whitelist for a role. If whitelist is nil or empty, it removes existing whitelist from role.
func (clnt *Client) SetWhitelist(policy *AdminPolicy, roleName string, whitelist []string) error {
	policy = clnt.getUsableAdminPolicy(policy)

	command := newAdminCommand(nil)
	return command.setWhitelist(clnt.cluster, policy, roleName, whitelist)
}

//-------------------------------------------------------
// Access Methods
//-------------------------------------------------------

// Cluster exposes the cluster object to the user
func (clnt *Client) Cluster() *Cluster {
	return clnt.cluster
}

// String implements the Stringer interface for client
func (clnt *Client) String() string {
	if clnt.cluster != nil {
		return clnt.cluster.String()
	}
	return ""
}

// Stats returns internal statistics regarding the inner state of the client and the cluster.
func (clnt *Client) Stats() (map[string]interface{}, error) {
	resStats := clnt.cluster.statsCopy()

	clusterStats := nodeStats{}
	for _, stats := range resStats {
		clusterStats.aggregate(&stats)
	}

	resStats["cluster-aggregated-stats"] = clusterStats

	b, err := json.Marshal(resStats)
	if err != nil {
		return nil, err
	}

	res := map[string]interface{}{}
	err = json.Unmarshal(b, &res)
	if err != nil {
		return nil, err
	}

	res["open-connections"] = clusterStats.ConnectionsOpen

	return res, nil
}

// WarmUp fills the connection pool with connections for all nodes.
// This is necessary on startup for high traffic programs.
// If the count is <= 0, the connection queue will be filled.
// If the count is more than the size of the pool, the pool will be filled.
// Note: One connection per node is reserved for tend operations and is not used for transactions.
func (clnt *Client) WarmUp(count int) (int, error) {
	return clnt.cluster.WarmUp(count)
}

//-------------------------------------------------------
// Internal Methods
//-------------------------------------------------------

func (clnt *Client) sendInfoCommand(timeout time.Duration, command string) (map[string]string, error) {
	node, err := clnt.cluster.GetRandomNode()
	if err != nil {
		return nil, err
	}

	node.tendConnLock.Lock()
	defer node.tendConnLock.Unlock()

	if err := node.initTendConn(timeout); err != nil {
		return nil, err
	}

	results, err := RequestInfo(node.tendConn, command)
	if err != nil {
		node.tendConn.Close()
		return nil, err
	}

	return results, nil
}

// batchExecute Uses sync.WaitGroup to run commands using multiple goroutines,
// and waits for their return
func (clnt *Client) batchExecute(policy *BatchPolicy, batchNodes []*batchNode, cmd batcher) (error, int) {
	var wg sync.WaitGroup
	filteredOut := 0

	// Use a goroutine per namespace per node
	errs := []error{}
	errm := new(sync.Mutex)

	wg.Add(len(batchNodes))
	if policy.ConcurrentNodes <= 0 {
		for _, batchNode := range batchNodes {
			newCmd := cmd.cloneBatchCommand(batchNode)
			go func(cmd command) {
				defer wg.Done()
				err := cmd.Execute()
				errm.Lock()
				if err != nil {
					errs = append(errs, err)
				}
				filteredOut += cmd.(batcher).filteredOut()
				errm.Unlock()
			}(newCmd)
		}
	} else {
		sem := semaphore.NewWeighted(int64(policy.ConcurrentNodes))
		ctx := context.Background()

		for _, batchNode := range batchNodes {
			if err := sem.Acquire(ctx, 1); err != nil {
				Logger.Error("Constraint Semaphore failed for Batch: %s", err.Error())
			}

			newCmd := cmd.cloneBatchCommand(batchNode)
			go func(cmd command) {
				defer sem.Release(1)
				defer wg.Done()
				err := cmd.Execute()
				errm.Lock()
				if err != nil {
					errs = append(errs, err)
				}
				filteredOut += cmd.(batcher).filteredOut()
				errm.Unlock()
			}(newCmd)
		}
	}

	wg.Wait()
	return mergeErrors(errs), filteredOut
}

//-------------------------------------------------------
// Policy Methods
//-------------------------------------------------------

func (clnt *Client) getUsablePolicy(policy *BasePolicy) *BasePolicy {
	if policy == nil {
		if clnt.DefaultPolicy != nil {
			return clnt.DefaultPolicy
		}
		return NewPolicy()
	}
	return policy
}

func (clnt *Client) getUsableBatchPolicy(policy *BatchPolicy) *BatchPolicy {
	if policy == nil {
		if clnt.DefaultBatchPolicy != nil {
			return clnt.DefaultBatchPolicy
		}
		return NewBatchPolicy()
	}
	return policy
}

func (clnt *Client) getUsableWritePolicy(policy *WritePolicy) *WritePolicy {
	if policy == nil {
		if clnt.DefaultWritePolicy != nil {
			return clnt.DefaultWritePolicy
		}
		return NewWritePolicy(0, 0)
	}
	return policy
}

func (clnt *Client) getUsableScanPolicy(policy *ScanPolicy) *ScanPolicy {
	if policy == nil {
		if clnt.DefaultScanPolicy != nil {
			res := clnt.DefaultScanPolicy
			res.validate()
			return res
		}
		return NewScanPolicy()
	}
	policy.validate()
	return policy
}

func (clnt *Client) getUsableQueryPolicy(policy *QueryPolicy) *QueryPolicy {
	if policy == nil {
		if clnt.DefaultQueryPolicy != nil {
			return clnt.DefaultQueryPolicy
		}
		return NewQueryPolicy()
	}
	return policy
}

func (clnt *Client) getUsableAdminPolicy(policy *AdminPolicy) *AdminPolicy {
	if policy == nil {
		if clnt.DefaultAdminPolicy != nil {
			return clnt.DefaultAdminPolicy
		}
		return NewAdminPolicy()
	}
	return policy
}

func (clnt *Client) getUsableInfoPolicy(policy *InfoPolicy) *InfoPolicy {
	if policy == nil {
		if clnt.DefaultInfoPolicy != nil {
			return clnt.DefaultInfoPolicy
		}
		return NewInfoPolicy()
	}
	return policy
}

//-------------------------------------------------------
// Utility Functions
//-------------------------------------------------------

// mergeErrors merges several errors into one
func mergeErrors(errs []error) error {
	switch len(errs) {
	case 0:
		return nil
	case 1:
		return errs[0]
	}

	var msg bytes.Buffer
	for _, err := range errs {
		if _, err := msg.WriteString(err.Error()); err != nil {
			return err
		}
		if _, err := msg.WriteString("\n"); err != nil {
			return err
		}
	}
	return errors.New(msg.String())
}