Example usage for com.amazonaws.services.simpledb.model DeleteAttributesRequest DeleteAttributesRequest

Introduction

In this page you can find the example usage for com.amazonaws.services.simpledb.model DeleteAttributesRequest DeleteAttributesRequest.

Prototype

public DeleteAttributesRequest(String domainName, String itemName, java.util.List<Attribute> attributes,
        UpdateCondition expected) 

Source Link

Document

Constructs a new DeleteAttributesRequest object.

Usage

From source file:org.grails.datastore.mapping.simpledb.util.SimpleDBTemplateImpl.java

License:Apache License

private void deleteAttributesVersionedInternal(String domainName, String id, List<Attribute> attributes,
        String expectedVersion, PersistentEntity persistentEntity, int attempt) throws DataAccessException {
    // If attribute list is empty AWS api will erase the whole item.
    // Do not do that, otherwise all the callers will have to check for empty list before calling
    if (!attributes.isEmpty()) {
        DeleteAttributesRequest request = new DeleteAttributesRequest(domainName, id, attributes,
                getOptimisticVersionCondition(expectedVersion));
        try {//from ww  w  .j a  v a2s  . c om
            sdb.deleteAttributes(request);
        } catch (AmazonServiceException e) {
            if (SimpleDBUtil.AWS_ERR_CODE_CONDITIONAL_CHECK_FAILED.equals(e.getErrorCode())) {
                throw new OptimisticLockingException(persistentEntity, id);
            } else if (SimpleDBUtil.AWS_ERR_CODE_NO_SUCH_DOMAIN.equals(e.getErrorCode())) {
                throw new IllegalArgumentException("no such domain: " + domainName, e);
            } else if (SimpleDBUtil.AWS_ERR_CODE_SERVICE_UNAVAILABLE.equals(e.getErrorCode())) {
                //retry after a small pause
                SimpleDBUtil.sleepBeforeRetry(attempt);
                attempt++;
                deleteAttributesVersionedInternal(domainName, id, attributes, expectedVersion, persistentEntity,
                        attempt);
            } else {
                throw e;
            }
        }
    }
}

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From source file:squash.booking.lambdas.core.OptimisticPersister.java

License:Apache License

@Override
public void delete(String itemName, Attribute attribute) throws Exception {

    if (!initialised) {
        throw new IllegalStateException("The optimistic persister has not been initialised");
    }//  ww w  . ja  v a2 s .com

    logger.log("About to delete attribute from simpledb item: " + itemName);

    AmazonSimpleDB client = getSimpleDBClient();

    // We retry the delete if necessary if we get a
    // ConditionalCheckFailed exception, i.e. if someone else modifies the
    // database between us reading and writing it.
    RetryHelper.DoWithRetries(() -> {
        try {
            // Get existing attributes (and version number), via consistent
            // read:
            ImmutablePair<Optional<Integer>, Set<Attribute>> versionedAttributes = get(itemName);

            if (!versionedAttributes.left.isPresent()) {
                logger.log(
                        "A version number attribute did not exist - this means no attributes exist, so we have nothing to delete.");
                return null;
            }
            if (!versionedAttributes.right.contains(attribute)) {
                logger.log("The attribute did not exist - so we have nothing to delete.");
                return null;
            }

            // Since it seems impossible to update the version number while
            // deleting an attribute, we first mark the attribute as inactive,
            // and then delete it.
            ReplaceableAttribute inactiveAttribute = new ReplaceableAttribute();
            inactiveAttribute.setName(attribute.getName());
            inactiveAttribute.setValue("Inactive" + attribute.getValue());
            inactiveAttribute.setReplace(true);
            put(itemName, versionedAttributes.left, inactiveAttribute);

            // Now we can safely delete the attribute, as other readers will now
            // ignore it.
            UpdateCondition updateCondition = new UpdateCondition();
            updateCondition.setName(inactiveAttribute.getName());
            updateCondition.setValue(inactiveAttribute.getValue());
            // Update will proceed unless the attribute no longer exists
            updateCondition.setExists(true);

            Attribute attributeToDelete = new Attribute();
            attributeToDelete.setName(inactiveAttribute.getName());
            attributeToDelete.setValue(inactiveAttribute.getValue());
            List<Attribute> attributesToDelete = new ArrayList<>();
            attributesToDelete.add(attributeToDelete);
            DeleteAttributesRequest simpleDBDeleteRequest = new DeleteAttributesRequest(simpleDbDomainName,
                    itemName, attributesToDelete, updateCondition);
            client.deleteAttributes(simpleDBDeleteRequest);
            logger.log("Deleted attribute from simpledb");
            return null;
        } catch (AmazonServiceException ase) {
            if (ase.getErrorCode().contains("AttributeDoesNotExist")) {
                // Case of trying to delete an attribute that no longer exists -
                // that's ok - it probably just means more than one person was
                // trying to delete the attribute at once. So swallow this
                // exception
                logger.log(
                        "Caught AmazonServiceException for AttributeDoesNotExist whilst deleting attribute so"
                                + " swallowing and continuing");
                return null;
            } else {
                throw ase;
            }
        }
    }, Exception.class, Optional.of("Database put failed - conditional check failed"), logger);
}

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