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snapshot.py
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# Copyright (C) 2018-2020 The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information
from typing import Iterator, List, Optional, Tuple
from swh.model.hashutil import hash_to_hex
from swh.model.model import (
OriginVisit,
OriginVisitStatus,
Sha1Git,
Snapshot,
SnapshotBranch,
TargetType,
)
from swh.storage.algos.origin import (
iter_origin_visit_statuses,
iter_origin_visits,
origin_get_latest_visit_status,
)
from swh.storage.interface import ListOrder, StorageInterface
def snapshot_get_all_branches(
storage: StorageInterface, snapshot_id: Sha1Git
) -> Optional[Snapshot]:
"""Get all the branches for a given snapshot
Args:
storage (swh.storage.interface.StorageInterface): the storage instance
snapshot_id (bytes): the snapshot's identifier
Returns:
dict: a dict with two keys:
* **id**: identifier of the snapshot
* **branches**: a dict of branches contained in the snapshot
whose keys are the branches' names.
"""
ret = storage.snapshot_get_branches(snapshot_id)
if not ret:
return None
next_branch = ret["next_branch"]
while next_branch:
data = storage.snapshot_get_branches(snapshot_id, branches_from=next_branch)
assert data, f"Snapshot {hash_to_hex(snapshot_id)} ceased to exist"
ret["branches"].update(data["branches"])
next_branch = data["next_branch"]
return Snapshot(id=ret["id"], branches=ret["branches"])
def snapshot_get_latest(
storage: StorageInterface,
origin: str,
allowed_statuses: Optional[List[str]] = None,
branches_count: Optional[int] = None,
) -> Optional[Snapshot]:
"""Get the latest snapshot for the given origin, optionally only from visits that have
one of the given allowed_statuses.
The branches of the snapshot are iterated in the lexicographical
order of their names.
Args:
storage: Storage instance
origin: the origin's URL
allowed_statuses: list of visit statuses considered
to find the latest snapshot for the visit. For instance,
``allowed_statuses=['full']`` will only consider visits that
have successfully run to completion.
branches_count: Optional parameter to retrieve snapshot with all branches
(default behavior when None) or not. If set to positive number, the snapshot
will be partial with only that number of branches.
Raises:
ValueError if branches_count is not a positive value
Returns:
The snapshot object if one is found matching the criteria or None.
"""
visit_status = origin_get_latest_visit_status(
storage,
origin,
allowed_statuses=allowed_statuses,
require_snapshot=True,
)
if not visit_status:
return None
snapshot_id = visit_status.snapshot
if not snapshot_id:
return None
if branches_count: # partial snapshot
if not isinstance(branches_count, int) or branches_count <= 0:
raise ValueError(
"Parameter branches_count must be a positive integer. "
f"Current value is {branches_count}"
)
snapshot = storage.snapshot_get_branches(
snapshot_id, branches_count=branches_count
)
if snapshot is None:
return None
return Snapshot(id=snapshot["id"], branches=snapshot["branches"])
else:
return snapshot_get_all_branches(storage, snapshot_id)
def snapshot_id_get_from_revision(
storage: StorageInterface, origin: str, revision_id: bytes
) -> Optional[bytes]:
"""Retrieve the most recent snapshot id targeting the revision_id for the given origin.
*Warning* This is a potentially highly costly operation
Returns
The snapshot id if found. None otherwise.
"""
res = visits_and_snapshots_get_from_revision(storage, origin, revision_id)
# they are sorted by descending date, so we just need to return the first one,
# if any.
for (visit, status, snapshot) in res:
return snapshot.id
return None
def visits_and_snapshots_get_from_revision(
storage: StorageInterface, origin: str, revision_id: bytes
) -> Iterator[Tuple[OriginVisit, OriginVisitStatus, Snapshot]]:
"""Retrieve all visits, visit statuses, and matching snapshot of the given origin,
such that the snapshot targets the revision_id.
*Warning* This is a potentially highly costly operation
Yields:
Tuples of (visit, status, snapshot)
"""
revision = storage.revision_get([revision_id])
if not revision:
return
for visit in iter_origin_visits(storage, origin, order=ListOrder.DESC):
assert visit.visit is not None
for visit_status in iter_origin_visit_statuses(
storage, origin, visit.visit, order=ListOrder.DESC
):
snapshot_id = visit_status.snapshot
if snapshot_id is None:
continue
snapshot = snapshot_get_all_branches(storage, snapshot_id)
if not snapshot:
continue
for branch_name, branch in snapshot.branches.items():
if (
branch is not None
and branch.target_type == TargetType.REVISION
and branch.target == revision_id
): # snapshot found
yield (visit, visit_status, snapshot)
def snapshot_resolve_alias(
storage: StorageInterface, snapshot_id: Sha1Git, alias_name: bytes
) -> Optional[SnapshotBranch]:
"""
Transitively resolve snapshot branch alias to its real target, and return it;
ie. follows every branch that is an alias, until a branch that isn't an alias
is found.
Args:
storage: Storage instance
snapshot_id: snapshot identifier
alias_name: name of the branch alias to resolve
Returns:
The first branch that isn't an alias, in the alias chain; or None if
there is no such branch (ie. either because of a cycle alias, or a dangling
branch).
"""
snapshot = storage.snapshot_get_branches(
snapshot_id, branches_from=alias_name, branches_count=1
)
if snapshot is None:
return None
if alias_name not in snapshot["branches"]:
return None
last_branch = snapshot["branches"][alias_name]
seen_aliases = {alias_name}
while last_branch is not None and last_branch.target_type == TargetType.ALIAS:
if last_branch.target in seen_aliases:
return None
alias_target = last_branch.target
snapshot = storage.snapshot_get_branches(
snapshot_id, branches_from=alias_target, branches_count=1
)
assert snapshot is not None
last_branch = snapshot["branches"].get(alias_target)
seen_aliases.add(alias_target)
return last_branch

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