in src/main/java/com/amazonaws/services/dynamodbv2/AmazonDynamoDBLockClient.java [707:748]
private LockItem upsertAndMonitorNewLock(AcquireLockOptions options, String key, Optional<String> sortKey,
boolean deleteLockOnRelease, Optional<SessionMonitor> sessionMonitor,
Optional<ByteBuffer> newLockData, Map<String, AttributeValue> item, String recordVersionNumber) {
final Map<String, String> expressionAttributeNames = new HashMap<>();
expressionAttributeNames.put(PK_PATH_EXPRESSION_VARIABLE, this.partitionKeyName);
final boolean updateExistingLockRecord = options.getUpdateExistingLockRecord();
final String conditionalExpression;
if (this.sortKeyName.isPresent()) {
conditionalExpression = ACQUIRE_LOCK_THAT_DOESNT_EXIST_PK_SK_CONDITION;
expressionAttributeNames.put(SK_PATH_EXPRESSION_VARIABLE, sortKeyName.get());
} else {
conditionalExpression = ACQUIRE_LOCK_THAT_DOESNT_EXIST_PK_CONDITION;
}
if (updateExistingLockRecord) {
// Remove keys from item to create updateExpression
item.remove(partitionKeyName);
if (sortKeyName.isPresent()) {
item.remove(sortKeyName.get());
}
final Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();
final String updateExpression = getUpdateExpressionAndUpdateNameValueMaps(item, expressionAttributeNames, expressionAttributeValues);
final UpdateItemRequest updateItemRequest = UpdateItemRequest.builder().tableName(tableName).key(getKeys(key, sortKey))
.updateExpression(updateExpression).expressionAttributeNames(expressionAttributeNames)
.expressionAttributeValues(expressionAttributeValues).conditionExpression(conditionalExpression).build();
logger.trace("Acquiring a new lock on " + partitionKeyName + "=" + key + ", " + this.sortKeyName + "=" + sortKey);
return updateItemAndStartSessionMonitor(options, key, sortKey, deleteLockOnRelease, sessionMonitor, newLockData, recordVersionNumber, updateItemRequest);
} else {
final PutItemRequest putItemRequest = PutItemRequest.builder().item(item).tableName(tableName)
.conditionExpression(conditionalExpression)
.expressionAttributeNames(expressionAttributeNames).build();
/* No one has the lock, go ahead and acquire it.
* The person storing the lock into DynamoDB should err on the side of thinking the lock will expire
* sooner than it actually will, so they start counting towards its expiration before the Put succeeds
*/
logger.trace("Acquiring a new lock on " + partitionKeyName + "=" + key + ", " + this.sortKeyName + "=" + sortKey);
return putLockItemAndStartSessionMonitor(options, key, sortKey, deleteLockOnRelease, sessionMonitor, newLockData, recordVersionNumber, putItemRequest);
}
}