/
persister.go
314 lines (301 loc) · 8.91 KB
/
persister.go
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package dynamo
import (
"errors"
"fmt"
"log"
"strconv"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/dynamodb"
"github.com/ourrootsorg/cms-server/model"
)
const (
// You can't use constants in struct tags (see https://github.com/golang/go/issues/4740),
// so if these are ever changed, they must also be replaced in all `dynamodbav` tags.
pkName = "pk"
skName = "sk"
gsiSkName = "altSort"
gsiName = "gsi_" + skName + "_" + gsiSkName
idSeparator = "#"
)
// Persister persists the model objects to DynammoDB
type Persister struct {
session *session.Session
svc *dynamodb.DynamoDB
tableName *string
}
// NewPersister constructs a new Persister
func NewPersister(session *session.Session, tableName string) (Persister, error) {
svc := dynamodb.New(session)
// These initial throughputs will be set to the real values by SetThroughput
err := ensureTableExists(svc, tableName, 5, 5)
p := Persister{
svc: svc,
tableName: &tableName,
}
return p, err
}
// GetSequenceValue returns a unique sequence value
func (p *Persister) GetSequenceValue() (uint32, error) {
v, err := p.GetMultipleSequenceValues(1)
return v[0], err
}
// GetMultipleSequenceValues returns a slice of unique sequence values
func (p *Persister) GetMultipleSequenceValues(cnt int) ([]uint32, error) {
if cnt < 1 || cnt > 10000 {
return nil, errors.New("Must request between 1 and 10,000 sequence values")
}
uii := &dynamodb.UpdateItemInput{
TableName: p.tableName,
Key: map[string]*dynamodb.AttributeValue{
pkName: {S: aws.String("sequence")},
skName: {S: aws.String("sequence")},
},
UpdateExpression: aws.String("ADD sequenceValue :i"),
ExpressionAttributeValues: map[string]*dynamodb.AttributeValue{
":i": {N: aws.String(strconv.Itoa(cnt))},
},
ReturnValues: aws.String("ALL_NEW"),
}
uio, err := p.svc.UpdateItem(uii)
if err != nil {
return nil, err
}
v, err := strconv.ParseUint(*uio.Attributes["sequenceValue"].N, 10, 32)
if err != nil {
return nil, err
}
ret := make([]uint32, cnt)
for i := uint32(0); i < uint32(cnt); i++ {
ret[i] = uint32(v) - uint32(cnt) + i + 1
}
return ret, err
}
// SetThroughput updates the Dynamo table throughput values
func (p Persister) SetThroughput(readThroughput, writeThroughput int) error {
cti := &dynamodb.UpdateTableInput{
TableName: p.tableName,
GlobalSecondaryIndexUpdates: []*dynamodb.GlobalSecondaryIndexUpdate{
{
Update: &dynamodb.UpdateGlobalSecondaryIndexAction{
IndexName: aws.String(gsiName),
ProvisionedThroughput: &dynamodb.ProvisionedThroughput{
ReadCapacityUnits: aws.Int64(int64(readThroughput)),
WriteCapacityUnits: aws.Int64(int64(writeThroughput)),
},
},
},
},
ProvisionedThroughput: &dynamodb.ProvisionedThroughput{
ReadCapacityUnits: aws.Int64(int64(readThroughput)),
WriteCapacityUnits: aws.Int64(int64(writeThroughput)),
},
}
_, err := p.svc.UpdateTable(cti)
if err != nil {
log.Printf("[ERROR] Failed to set final table throughput %s: %v", *p.tableName, err)
return err
}
log.Printf("[INFO] Set table throughput to read %d, write %d", readThroughput, writeThroughput)
return nil
}
func (p Persister) truncateEntity(name string) error {
log.Printf("[DEBUG] Truncating entity '%s'", name)
qi := &dynamodb.QueryInput{
TableName: p.tableName,
IndexName: aws.String(gsiName),
KeyConditionExpression: aws.String(skName + " = :sk"),
ExpressionAttributeValues: map[string]*dynamodb.AttributeValue{
":sk": {
S: aws.String(name),
},
},
}
qo, err := p.svc.Query(qi)
if err != nil {
log.Printf("[ERROR] Failed to get entity type '%s'. err: %v", name, err)
return model.NewError(model.ErrOther, err.Error())
}
var batchCount, count int
batch := make([]map[string]*dynamodb.AttributeValue, 0)
for {
// Process results
for _, item := range qo.Items {
batch = append(batch, map[string]*dynamodb.AttributeValue{
pkName: {
S: item["pk"].S,
},
skName: {
S: item["sk"].S,
},
})
batchCount++
count++
if batchCount >= batchSize {
err = p.deleteBatch(batch)
if err != nil {
return err
}
batchCount = 0
batch = make([]map[string]*dynamodb.AttributeValue, 0)
}
}
if qo.LastEvaluatedKey == nil {
break
}
qi.ExclusiveStartKey = qo.LastEvaluatedKey
qo, err = p.svc.Query(qi)
if err != nil {
log.Printf("[ERROR] Failed to get entity type '%s'. err: %v", name, err)
return model.NewError(model.ErrOther, err.Error())
}
}
if batchCount > 0 {
err = p.deleteBatch(batch)
if err != nil {
return err
}
}
log.Printf("[INFO] Removed %d records for entity '%s'", count, name)
return nil
}
func (p Persister) deleteBatch(batch []map[string]*dynamodb.AttributeValue) error {
ris := map[string][]*dynamodb.WriteRequest{}
for _, key := range batch {
ris[*p.tableName] = append(ris[*p.tableName],
&dynamodb.WriteRequest{
DeleteRequest: &dynamodb.DeleteRequest{
Key: key,
},
},
)
}
bwii := &dynamodb.BatchWriteItemInput{
RequestItems: ris,
}
var bwio *dynamodb.BatchWriteItemOutput
var err error
for bwio == nil || (len(bwio.UnprocessedItems) > 0 && err == nil) {
if bwio != nil && len(bwio.UnprocessedItems) > 0 {
bwii.RequestItems = bwio.UnprocessedItems
}
bwio, err = p.svc.BatchWriteItem(bwii)
}
if err != nil {
msg := fmt.Sprintf("[ERROR] Failed to delete batch %#v: %v", bwii, err)
log.Printf("[ERROR] " + msg)
return errors.New(msg)
}
log.Printf("[DEBUG] Deleted batch of %d items", len(batch))
return nil
}
func ensureTableExists(svc *dynamodb.DynamoDB, tableName string, initialReadThroughput, initialWriteThroughput int) error {
// See if the table exists already
err := waitForTable(svc, tableName)
if err == nil {
// Perhaps we should compare the schema to what we expect
// if so, see https://github.com/dollarshaveclub/dynamo-drift
return nil
}
if aerr, ok := err.(awserr.Error); ok {
if aerr.Code() != dynamodb.ErrCodeResourceNotFoundException {
return fmt.Errorf("[ERROR] Unexpected error when checking DynamoDB table: %v", err)
}
} else {
return fmt.Errorf("[ERROR] Unexpected error when checking DynamoDB table: %v", err)
}
log.Printf("[INFO] Creating table %s", tableName)
// Couldn't describe it, so try to create it
cti := &dynamodb.CreateTableInput{
TableName: &tableName,
AttributeDefinitions: []*dynamodb.AttributeDefinition{
{
AttributeName: aws.String(pkName),
AttributeType: aws.String("S"),
},
{
AttributeName: aws.String(skName),
AttributeType: aws.String("S"),
},
{
AttributeName: aws.String(gsiSkName),
AttributeType: aws.String("S"),
},
},
KeySchema: []*dynamodb.KeySchemaElement{
{
AttributeName: aws.String(pkName),
KeyType: aws.String("HASH"),
},
{
AttributeName: aws.String(skName),
KeyType: aws.String("RANGE"),
},
},
GlobalSecondaryIndexes: []*dynamodb.GlobalSecondaryIndex{
{
IndexName: aws.String(gsiName),
KeySchema: []*dynamodb.KeySchemaElement{
{
AttributeName: aws.String(skName),
KeyType: aws.String("HASH"),
},
{
AttributeName: aws.String(gsiSkName),
KeyType: aws.String("RANGE"),
},
},
Projection: &dynamodb.Projection{
ProjectionType: aws.String("ALL"),
},
ProvisionedThroughput: &dynamodb.ProvisionedThroughput{
ReadCapacityUnits: aws.Int64(int64(initialReadThroughput)),
WriteCapacityUnits: aws.Int64(int64(initialWriteThroughput)),
},
},
},
ProvisionedThroughput: &dynamodb.ProvisionedThroughput{
ReadCapacityUnits: aws.Int64(int64(initialReadThroughput)),
WriteCapacityUnits: aws.Int64(int64(initialWriteThroughput)),
},
}
_, err = svc.CreateTable(cti)
if err != nil {
log.Printf("[ERROR] Failed to create table %s: %v", tableName, err)
return err
}
return waitForTable(svc, tableName)
}
func waitForTable(svc *dynamodb.DynamoDB, tableName string) error {
cnt := 0
for {
// See if the table exists
dto, err := svc.DescribeTable(&dynamodb.DescribeTableInput{
TableName: &tableName,
})
if err != nil {
log.Printf("[INFO] Couldn't describe DynamoDB table %s: %v", tableName, err)
return err
}
if *dto.Table.TableStatus == "ACTIVE" {
log.Printf("[DEBUG] DynamoDB table %s is ACTIVE", tableName)
return nil
}
if *dto.Table.TableStatus == "CREATING" || *dto.Table.TableStatus == "UPDATING" && cnt < 10 {
log.Printf("[DEBUG] Waiting for DynamoDB table %s to be ACTIVE. Current status is %s", tableName, *dto.Table.TableStatus)
// wait a bit before trying again
time.Sleep(5 * time.Second)
} else {
return fmt.Errorf("Unexpected status while waiting for DynamoDB table %s to be ready: %s", tableName, *dto.Table.TableStatus)
}
cnt++
}
}
func compareToAWSError(err error, awsErrorCode string) bool {
if aerr, ok := err.(awserr.Error); ok {
return aerr.Code() == awsErrorCode
}
return false
}