glance_store.common.utils module¶
System-level utilities and helper functions.
- class glance_store.common.utils.CooperativeReader(fd)¶
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)¶
Return the next chunk of the underlying iterator.
This is replaced with cooperative_read in __init__ if the underlying fd already supports read().
- glance_store.common.utils.chunkiter(fp, chunk_size=65536)¶
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_store.common.utils.chunkreadable(iter, chunk_size=65536)¶
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_store.common.utils.cooperative_iter(iter)¶
Return an iterator which schedules after each iteration. This can prevent eventlet thread starvation.
- Parameters
iter – an iterator to wrap
- glance_store.common.utils.cooperative_read(fd)¶
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_store.common.utils.get_hasher(hash_algo, usedforsecurity=True)¶
Returns the required hasher, given the hashing algorithm. This is primarily to ensure that the hash algorithm is correctly chosen when executed on a FIPS enabled system
- Parameters
hash_algo – hash algorithm requested
usedforsecurity – whether the hashes are used in a security context
- glance_store.common.utils.is_uuid_like(val)¶
Returns validation of a value as a UUID.
For our purposes, a UUID is a canonical form string: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa