mirror of
https://github.com/rocky-linux/peridot.git
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135 lines
4.6 KiB
Go
135 lines
4.6 KiB
Go
/*
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Copyright 2019 github.com/ucirello
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package dynamolock
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import (
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"context"
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"time"
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"github.com/aws/aws-sdk-go/aws"
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"github.com/aws/aws-sdk-go/service/dynamodb"
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"github.com/aws/aws-sdk-go/service/dynamodb/expression"
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)
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// SendHeartbeatOption allows to proceed with Lock content changes in the
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// heartbeat cycle.
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type SendHeartbeatOption func(*sendHeartbeatOptions)
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type sendHeartbeatOptions struct {
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lockItem *Lock
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data []byte
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deleteData bool
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}
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// DeleteData removes the Lock data on heartbeat.
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func DeleteData() SendHeartbeatOption {
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return func(o *sendHeartbeatOptions) {
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o.deleteData = true
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}
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}
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// ReplaceHeartbeatData overrides the content of the Lock in the heartbeat cycle.
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func ReplaceHeartbeatData(data []byte) SendHeartbeatOption {
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return func(o *sendHeartbeatOptions) {
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o.deleteData = false
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o.data = data
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}
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}
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// SendHeartbeat indicates that the given lock is still being worked on. If
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// using WithHeartbeatPeriod > 0 when setting up this object, then this method
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// is unnecessary, because the background thread will be periodically calling it
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// and sending heartbeats. However, if WithHeartbeatPeriod = 0, then this method
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// must be called to instruct DynamoDB that the lock should not be expired.
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func (c *Client) SendHeartbeat(lockItem *Lock, opts ...SendHeartbeatOption) error {
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return c.SendHeartbeatWithContext(context.Background(), lockItem, opts...)
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}
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// SendHeartbeatWithContext indicates that the given lock is still being worked
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// on. If using WithHeartbeatPeriod > 0 when setting up this object, then this
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// method is unnecessary, because the background thread will be periodically
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// calling it and sending heartbeats. However, if WithHeartbeatPeriod = 0, then
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// this method must be called to instruct DynamoDB that the lock should not be
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// expired. The given context is passed down to the underlying dynamoDB call.
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func (c *Client) SendHeartbeatWithContext(ctx context.Context, lockItem *Lock, opts ...SendHeartbeatOption) error {
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if c.isClosed() {
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return ErrClientClosed
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}
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sho := &sendHeartbeatOptions{
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lockItem: lockItem,
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}
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for _, opt := range opts {
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opt(sho)
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}
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return c.sendHeartbeat(ctx, sho)
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}
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func (c *Client) sendHeartbeat(ctx context.Context, options *sendHeartbeatOptions) error {
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leaseDuration := c.leaseDuration
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lockItem := options.lockItem
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lockItem.semaphore.Lock()
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defer lockItem.semaphore.Unlock()
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if lockItem.isExpired() || lockItem.ownerName != c.ownerName || lockItem.isReleased {
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c.locks.Delete(lockItem.uniqueIdentifier())
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return &LockNotGrantedError{msg: "cannot send heartbeat because lock is not granted"}
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}
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// Set up condition for UpdateItem. Basically any changes require:
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// 1. I own the lock
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// 2. I know the current version number
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// 3. The lock already exists (UpdateItem API can cause a new item to be created if you do not condition the primary keys with attribute_exists)
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newRvn := c.generateRecordVersionNumber()
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cond := ownershipLockCondition(c.partitionKeyName, lockItem.recordVersionNumber, lockItem.ownerName)
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update := expression.
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Set(leaseDurationAttr, expression.Value(leaseDuration.String())).
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Set(rvnAttr, expression.Value(newRvn))
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if options.deleteData {
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update.Remove(dataAttr)
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} else if len(options.data) > 0 {
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update.Set(dataAttr, expression.Value(options.data))
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}
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updateExpr, _ := expression.NewBuilder().WithCondition(cond).WithUpdate(update).Build()
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updateItemInput := &dynamodb.UpdateItemInput{
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TableName: aws.String(c.tableName),
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Key: c.getItemKeys(lockItem),
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ConditionExpression: updateExpr.Condition(),
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UpdateExpression: updateExpr.Update(),
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ExpressionAttributeNames: updateExpr.Names(),
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ExpressionAttributeValues: updateExpr.Values(),
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}
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lastUpdateOfLock := time.Now()
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_, err := c.dynamoDB.UpdateItemWithContext(ctx, updateItemInput)
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if err != nil {
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err := parseDynamoDBError(err, "already acquired lock, stopping heartbeats")
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if isLockNotGrantedError(err) {
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c.locks.Delete(lockItem.uniqueIdentifier())
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}
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return err
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}
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lockItem.updateRVN(newRvn, lastUpdateOfLock, leaseDuration)
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return nil
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}
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