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"""TAU Commander hierarchical file and record storage system.
System-level records are globally readable and writable, depending on the user's
system access level. System-level is a good place for software package installations
and some system-specific configurations, e.g. target or compiler configurations.
The system level exists only when :any:`SYSTEM_PREFIX` is set. A system prefix that doesn't
exist is treated as an empty, read-only level until it is created.
User-level records are readable and writable by (at least) the user. User-level is also
where software is installed when there is no system level or the user doesn't have write access to it.
It's a good place for user-specific records, i.e. preferences or encrypted login credentials.
Project-level records define the project and its member components. The user may also
want to install software packages at the project level to avoid quotas or in situations
where :any:`USER_PREFIX` is not accessible from cluster compute nodes.
"""
import contextlib
from taucmdr import SYSTEM_PREFIX, USER_PREFIX
from taucmdr.error import ConfigurationError
from taucmdr.cf.storage import StorageError
from taucmdr.cf.storage.storage_dispatch import StorageDispatch, ProjectStorageDispatch
SYSTEM_STORAGE = StorageDispatch('system', SYSTEM_PREFIX, create_prefix=False) if SYSTEM_PREFIX else None
"""System-level data storage, or None if there is no system level."""
USER_STORAGE = StorageDispatch('user', USER_PREFIX)
"""User-level data storage."""
PROJECT_STORAGE = ProjectStorageDispatch()
"""Project-level data storage."""
ORDERED_LEVELS = tuple(level for level in (PROJECT_STORAGE, USER_STORAGE, SYSTEM_STORAGE) if level is not None)
"""All storage levels in their preferred order."""
STORAGE_LEVELS = {level.name: level for level in ORDERED_LEVELS}
"""All storage levels indexed by their names."""
[docs]
def require_system_storage():
"""Return the system storage level.
Raises:
ConfigurationError: No system level exists.
"""
if SYSTEM_STORAGE is None:
raise ConfigurationError(
"No system-level storage is configured.",
"Set the environment variable TAUCMDR_SYSTEM_PREFIX to a directory for shared TAU builds.")
return SYSTEM_STORAGE
[docs]
def writable_system_storage():
"""Return the system storage level for a command, creating its prefix if needed.
Guarantees that a returned level is writable, or else raises an error.
Raises:
ConfigurationError: No system level exists, or it can't be written.
"""
storage = require_system_storage()
storage.connect_filesystem()
if not storage.is_writable():
raise ConfigurationError(f"Cannot write to system-level storage in '{storage.prefix}'.",
"Check that you have `write` access, e.g. as a member of the group that owns it.")
return storage
[docs]
def highest_writable_storage():
"""Return the highest-priority writable storage level, caching the result.
Searches :data:`ORDERED_LEVELS` in reverse (system, user, project) and returns
the first writable level found.
Raises:
StorageError: No writable storage levels are available.
"""
try:
return highest_writable_storage.value
except AttributeError as err:
for storage in reversed(ORDERED_LEVELS):
if storage.is_writable():
highest_writable_storage.value = storage
break
else:
raise StorageError("No writable storage levels") from err
return highest_writable_storage.value
[docs]
def search_levels():
"""Return the storage levels to search for installed software packages and their source archives.
This is :data:`ORDERED_LEVELS`, or only the level given to :any:`build_level` while that is active.
"""
return getattr(search_levels, 'only', ORDERED_LEVELS)
[docs]
@contextlib.contextmanager
def build_level(storage):
"""Find, download and install software packages only in `storage` while the context is active.
Packages already installed at other levels are ignored, so everything the context builds ends up in `storage`.
Args:
storage: The storage level, e.g. :any:`SYSTEM_STORAGE`.
"""
missing = object()
old_writable = getattr(highest_writable_storage, 'value', missing)
old_only = getattr(search_levels, 'only', missing)
highest_writable_storage.value = storage
search_levels.only = (storage,)
try:
yield storage
finally:
for func, attr, old in ((highest_writable_storage, 'value', old_writable),
(search_levels, 'only', old_only)):
if old is missing:
delattr(func, attr)
else:
setattr(func, attr, old)