The glance.common.utils Module¶

System-level utilities and helper functions.

class glance.common.utils.CooperativeReader(fd)[source]¶

Bases: object

An eventlet thread friendly class for reading in image data.

When accessing data either through the iterator or the read method we perform a sleep to allow a co-operative yield. When there is more than one image being uploaded/downloaded this prevents eventlet thread starvation, ie allows all threads to be scheduled periodically rather than having the same thread be continuously active.

read(length=None)[source]¶

Return the requested amount of bytes, fetching the next chunk of the underlying iterator when needed.

This is replaced with cooperative_read in __init__ if the underlying fd already supports read().

class glance.common.utils.LimitingReader(data, limit)[source]¶

Bases: object

Reader designed to fail when reading image data past the configured allowable amount.

read(i)[source]¶

glance.common.utils.chunkiter(fp, chunk_size=65536)[source]¶

Return an iterator to a file-like obj which yields fixed size chunks

Parameters:	fp – a file-like object chunk_size – maximum size of chunk

glance.common.utils.chunkreadable(iter, chunk_size=65536)[source]¶

Wrap a readable iterator with a reader yielding chunks of a preferred size, otherwise leave iterator unchanged.

Parameters:	iter – an iter which may also be readable chunk_size – maximum size of chunk

glance.common.utils.cooperative_iter(iter)[source]¶

Return an iterator which schedules after each iteration. This can prevent eventlet thread starvation.

Parameters:	iter – an iterator to wrap

glance.common.utils.cooperative_read(fd)[source]¶

Wrap a file descriptor’s read with a partial function which schedules after each read. This can prevent eventlet thread starvation.

Parameters:	fd – a file descriptor to wrap

glance.common.utils.create_mashup_dict(image_meta)[source]¶

Returns a dictionary-like mashup of the image core properties and the image custom properties from given image metadata.

Parameters:	image_meta – metadata of image with core and custom properties

glance.common.utils.evaluate_filter_op(value, operator, threshold)[source]¶

Evaluate a comparison operator. Designed for use on a comparative-filtering query field.

Parameters:	value – evaluated against the operator, as left side of expression operator – any supported filter operation threshold – to compare value against, as right side of expression
Raises:	InvalidFilterOperatorValue – if an unknown operator is provided
Returns:	boolean result of applied comparison

glance.common.utils.get_image_meta_from_headers(response)[source]¶

Processes HTTP headers from a supplied response that match the x-image-meta and x-image-meta-property and returns a mapping of image metadata and properties

Parameters:	response – Response to process

glance.common.utils.get_test_suite_socket()[source]¶

glance.common.utils.image_meta_to_http_headers(image_meta)[source]¶

Returns a set of image metadata into a dict of HTTP headers that can be fed to either a Webob Request object or an httplib.HTTP(S)Connection object

Parameters:	image_meta – Mapping of image metadata

glance.common.utils.is_valid_fqdn(fqdn)[source]¶

Verify whether a host is a valid FQDN.

glance.common.utils.is_valid_hostname(hostname)[source]¶

Verify whether a hostname (not an FQDN) is valid.

glance.common.utils.mutating(func)[source]¶

Decorator to enforce read-only logic

glance.common.utils.no_4byte_params(f)[source]¶

Checks that no 4 byte unicode characters are allowed in dicts’ keys/values and string’s parameters

glance.common.utils.parse_valid_host_port(host_port)[source]¶

Given a “host:port” string, attempts to parse it as intelligently as possible to determine if it is valid. This includes IPv6 [host]:port form, IPv4 ip:port form, and hostname:port or fqdn:port form.

Invalid inputs will raise a ValueError, while valid inputs will return a (host, port) tuple where the port will always be of type int.

glance.common.utils.safe_mkdirs(path)[source]¶

glance.common.utils.setup_remote_pydev_debug(host, port)[source]¶

glance.common.utils.split_filter_op(expression)[source]¶

Split operator from threshold in an expression. Designed for use on a comparative-filtering query field. When no operator is found, default to an equality comparison.

Parameters:	expression – the expression to parse
Returns:	a tuple (operator, threshold) parsed from expression

glance.common.utils.split_filter_value_for_quotes(value)[source]¶

Split filter values

Split values by commas and quotes for ‘in’ operator, according api-wg.

glance.common.utils.stash_conf_values()[source]¶

Make a copy of some of the current global CONF’s settings. Allows determining if any of these values have changed when the config is reloaded.

glance.common.utils.validate_key_cert(key_file, cert_file)[source]¶

glance.common.utils.validate_quotes(value)[source]¶

Validate filter values

Validation opening/closing quotes in the expression.