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strings.go
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strings.go
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package redimo
import (
"context"
"strings"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/service/dynamodb"
)
const emptySK = "/"
// GET fetches the value at the given key. If the key does not exist, the ReturnValue will be Empty().
//
// Works similar to https://redis.io/commands/get
func (c Client) GET(key string) (val ReturnValue, err error) {
resp, err := c.ddbClient.GetItemRequest(&dynamodb.GetItemInput{
ConsistentRead: aws.Bool(c.consistentReads),
Key: keyDef{pk: key, sk: emptySK}.toAV(),
TableName: aws.String(c.table),
}).Send(context.TODO())
if err != nil || len(resp.Item) == 0 {
return
}
val = ReturnValue{resp.Item[vk]}
return
}
// SET stores the given Value at the given key. If called as SET("key", "value", None), SET is
// unconditional and is not expected to fail.
//
// The condition flags IfNotExists and IfAlreadyExists can be specified, and if they are
// the SET becomes conditional and will return false if the condition fails.
//
// Works similar to https://redis.io/commands/set
func (c Client) SET(key string, value Value, flag Flag) (ok bool, err error) {
builder := newExpresionBuilder()
builder.updateSET(vk, value)
if flag == IfNotExists {
builder.addConditionNotExists(pk)
}
if flag == IfAlreadyExists {
builder.addConditionExists(pk)
}
_, err = c.ddbClient.UpdateItemRequest(&dynamodb.UpdateItemInput{
ConditionExpression: builder.conditionExpression(),
ExpressionAttributeNames: builder.expressionAttributeNames(),
ExpressionAttributeValues: builder.expressionAttributeValues(),
UpdateExpression: builder.updateExpression(),
Key: keyDef{
pk: key,
sk: emptySK,
}.toAV(),
TableName: aws.String(c.table),
}).Send(context.TODO())
if conditionFailureError(err) {
return false, nil
}
if err != nil {
return
}
return true, nil
}
// SETNX is equivalent to SET(key, value, Flags{IfNotExists})
//
// Works similar to https://redis.io/commands/setnx
func (c Client) SETNX(key string, value Value) (ok bool, err error) {
return c.SET(key, value, IfNotExists)
}
// GETSET gets the value at the key and atomically sets it to a new value.
//
// Works similar to https://redis.io/commands/getset
func (c Client) GETSET(key string, value Value) (oldValue ReturnValue, err error) {
builder := newExpresionBuilder()
builder.updateSET(vk, value)
resp, err := c.ddbClient.UpdateItemRequest(&dynamodb.UpdateItemInput{
ConditionExpression: builder.conditionExpression(),
ExpressionAttributeNames: builder.expressionAttributeNames(),
ExpressionAttributeValues: builder.expressionAttributeValues(),
UpdateExpression: builder.updateExpression(),
Key: keyDef{
pk: key,
sk: emptySK,
}.toAV(),
ReturnValues: dynamodb.ReturnValueAllOld,
TableName: aws.String(c.table),
}).Send(context.TODO())
if err != nil || len(resp.Attributes) == 0 {
return
}
oldValue = parseItem(resp.Attributes).val
return
}
// MGET fetches the given keys atomically in a transaction. The call is limited to 25 keys and 4MB.
// See https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_TransactGetItems.html
//
// Works similar to https://redis.io/commands/mget
func (c Client) MGET(keys ...string) (values map[string]ReturnValue, err error) {
values = make(map[string]ReturnValue)
inputRequests := make([]dynamodb.TransactGetItem, len(keys))
for i, key := range keys {
inputRequests[i] = dynamodb.TransactGetItem{
Get: &dynamodb.Get{
Key: keyDef{
pk: key,
sk: emptySK,
}.toAV(),
ProjectionExpression: aws.String(strings.Join([]string{vk, pk}, ", ")),
TableName: aws.String(c.table),
},
}
}
resp, err := c.ddbClient.TransactGetItemsRequest(&dynamodb.TransactGetItemsInput{
TransactItems: inputRequests,
}).Send(context.TODO())
if err != nil {
return
}
for _, item := range resp.Responses {
pi := parseItem(item.Item)
values[pi.pk] = pi.val
}
return
}
// MSET sets the given keys and values atomically in a transaction. The call is limited to 25 keys and 4MB.
// See https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_TransactWriteItems.html
//
// Works similar to https://redis.io/commands/mset
func (c Client) MSET(data map[string]Value) (err error) {
_, err = c.mset(data, Flags{})
return
}
// MSETNX sets the given keys and values atomically in a transaction, but only if none of the given
// keys exist. If one or more of the keys already exist, nothing will be changed and MSETNX will return false.
//
// Works similar to https://redis.io/commands/msetnx
func (c Client) MSETNX(data map[string]Value) (ok bool, err error) {
return c.mset(data, Flags{IfNotExists})
}
func (c Client) mset(data map[string]Value, flags Flags) (ok bool, err error) {
inputs := make([]dynamodb.TransactWriteItem, 0, len(data))
for k, v := range data {
builder := newExpresionBuilder()
if flags.has(IfNotExists) {
builder.addConditionNotExists(pk)
}
builder.updateSET(vk, v)
inputs = append(inputs, dynamodb.TransactWriteItem{
Update: &dynamodb.Update{
ConditionExpression: builder.conditionExpression(),
ExpressionAttributeNames: builder.expressionAttributeNames(),
ExpressionAttributeValues: builder.expressionAttributeValues(),
Key: keyDef{
pk: k,
sk: emptySK,
}.toAV(),
TableName: aws.String(c.table),
UpdateExpression: builder.updateExpression(),
},
})
}
_, err = c.ddbClient.TransactWriteItemsRequest(&dynamodb.TransactWriteItemsInput{
ClientRequestToken: nil,
TransactItems: inputs,
}).Send(context.TODO())
if conditionFailureError(err) {
return false, nil
}
if err != nil {
return false, err
}
return true, nil
}
func (c Client) INCRBYFLOAT(key string, delta float64) (after float64, err error) {
rv, err := c.incr(key, FloatValue{delta})
if err == nil {
after = rv.Float()
}
return
}
func (c Client) incr(key string, value Value) (newValue ReturnValue, err error) {
builder := newExpresionBuilder()
builder.keys[vk] = struct{}{}
resp, err := c.ddbClient.UpdateItemRequest(&dynamodb.UpdateItemInput{
ExpressionAttributeNames: builder.expressionAttributeNames(),
ExpressionAttributeValues: map[string]dynamodb.AttributeValue{
":delta": value.ToAV(),
},
Key: keyDef{pk: key, sk: emptySK}.toAV(),
ReturnValues: dynamodb.ReturnValueAllNew,
TableName: aws.String(c.table),
UpdateExpression: aws.String("ADD #val :delta"),
}).Send(context.TODO())
if err == nil {
newValue = ReturnValue{resp.UpdateItemOutput.Attributes[vk]}
}
return
}
func (c Client) INCR(key string) (after int64, err error) {
return c.INCRBY(key, 1)
}
func (c Client) DECR(key string) (after int64, err error) {
return c.INCRBY(key, -1)
}
func (c Client) INCRBY(key string, delta int64) (after int64, err error) {
rv, err := c.incr(key, IntValue{delta})
if err == nil {
after = rv.Int()
}
return
}
func (c Client) DECRBY(key string, delta int64) (after int64, err error) {
return c.INCRBY(key, -delta)
}