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Switch to ref-per-commit approach

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This enables single-commit push, and simpler deletion of old snapshots.
This commit is contained in:
jan 2020-12-24 22:34:49 -08:00
parent 055a7cf581
commit 6558595572
1 changed files with 96 additions and 46 deletions
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140
lethe/lethe.py
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@ -3,7 +3,7 @@
Git snapshotting tool
"""
from typing import List, Union, Optional
from typing import Sequence, Union, Optional
import subprocess
import tempfile
import datetime
@ -11,18 +11,25 @@ import argparse
from itertools import chain
def _run(command: Union[str, List[str]], **kwargs) -> str:
def _run(command: Union[str, Sequence[str]], **kwargs) -> str:
"""
Wrapper for `subprocess.run()`:
- Accepts args as either a list of strings or space-delimited string
- Captures and returns stdout
Args:
command: A list of strings or a space-delimited string
**kwargs: Passed to `subprocess.run()`
Returns:
Captured stdout
"""
args: Sequence[str]
if isinstance(command, str):
args = command.split()
else:
args = command
# print('run', ' '.join(args))
result = subprocess.run(args, stdout=subprocess.PIPE, **kwargs)
return result.stdout.decode().strip()
@ -33,14 +40,14 @@ def get_latest_commit(short: bool = True, cwd: Optional[str] = None) -> str:
This includes non-lethe commits.
"""
fmt = 'h' if short else 'H'
return _run('git log --all -1 --format=%{}'.format(fmt), cwd=cwd)
return _run(f'git log --all -1 --format=%{fmt}', cwd=cwd)
def shorten_hash(sha: str, cwd: Optional[str] = None) -> str:
"""
Get the short version of a hash
"""
return _run('git rev-parse --short {}'.format(sha), cwd=cwd)
return _run(f'git rev-parse --short {sha}', cwd=cwd)
def get_root(cwd: Optional[str] = None) -> str:
@ -76,7 +83,7 @@ def get_tree(ref: str, cwd: Optional[str] = None) -> str:
def commit_tree(tree: str,
parents: List[str],
parents: Sequence[str],
message: Optional[str] = None,
cwd: Optional[str] = None,
) -> str:
@ -95,6 +102,7 @@ def commit_tree(tree: str,
def update_ref(target_ref: str,
target_commit: str,
old_commit: Optional[str] = None,
*,
message: str = 'new snapshot',
cwd: Optional[str] = None,
) -> str:
@ -111,13 +119,23 @@ def update_ref(target_ref: str,
def push_ref(remote: str = 'origin',
target_ref: str = 'refs/lethe/HEAD',
target_ref: str = 'refs/lethe/LATEST',
remote_ref: Optional[str] = None,
*,
cwd: Optional[str] = None,
) -> str:
"""
Push `target_ref` to `remote` as `remote_ref`.
By default, `remote_ref` will be the same as `target_ref`.
Args:
remote: git remote to push to (default 'origin')
target_ref: ref to push (default 'refs/lethe/LATEST')
remote_ref: ref to push to (default same as `target_ref`)
cwd: Repository directory. Default is current working directory.
Returns:
git command stdout
"""
if remote_ref is None:
remote_ref = target_ref
@ -125,29 +143,52 @@ def push_ref(remote: str = 'origin',
def fetch_ref(remote: str = 'origin',
remote_ref: str = 'refs/lethe/HEAD',
remote_ref: str = 'refs/lethe/LATEST',
target_ref: Optional[str] = None,
*,
cwd: Optional[str] = None,
) -> str:
"""
Fetch `remote_ref` from `remote` as `target_ref`.
By default, `target_ref` will be the same as `remote_ref`.
Args:
remote: git remote to push to (default 'origin')
remote_ref: ref to fetch from (default 'refs/lethe/LATEST')
target_ref: ref to fetch to (default same as `remote_ref`)
cwd: Repository directory. Default is current working directory.
Returns:
git command stdout
"""
if target_ref is None:
target_ref = remote_ref
return _run(['git', 'fetch', remote, remote_ref + ':' + target_ref], cwd=cwd)
def deref_symref(ref: str, cwd: Optional[str] = None) -> str:
def deref_symref(ref: str,
*,
cwd: Optional[str] = None,
) -> str:
"""
Dereference a symbolic ref
"""
return _run(['git', 'symbolic-ref', '--quiet', ref], cwd=cwd)
def find_merge_base(commits: List[str], cwd: Optional[str] = None) -> str:
def find_merge_base(commits: Sequence[str],
*,
cwd: Optional[str] = None,
) -> str:
"""
Find the "best common ancestor" commit.
Args:
commits: Collection of commits to find the best common ancestor for
cwd: Repository directory. Default is current working directory.
Returns:
Hash of the best common ancestor commit
"""
if len(commits) == 0:
raise Exception('Called find_merge_base with no commits!')
@ -159,7 +200,7 @@ def find_merge_base(commits: List[str], cwd: Optional[str] = None) -> str:
return base
def snap_tree(cwd: Optional[str] = None) -> str:
def snap_tree(*, cwd: Optional[str] = None) -> str:
"""
Create a new tree, consisting of all non-ignored files in the repository.
Return the hash of the tree.
@ -173,9 +214,10 @@ def snap_tree(cwd: Optional[str] = None) -> str:
return tree
def snap_ref(parent_refs: List[str],
target_refs: List[str],
def snap_ref(parent_refs: Sequence[str],
target_refs: Sequence[str],
message: Optional[str] = None,
*,
cwd: Optional[str] = None,
) -> str:
"""
@ -185,16 +227,7 @@ def snap_ref(parent_refs: List[str],
parent_commits = [c for c in [get_commit(p, cwd=cwd) for p in parent_refs] if c]
old_commits = [get_commit(t, cwd=cwd) for t in target_refs]
extant_old_commits = list(set(c for c in old_commits if c))
new_parents = list(set(p for p in parent_commits
if p != find_merge_base([p] + extant_old_commits, cwd=cwd)))
# if not new_parents:
# tree_unchanged = all(new_tree == get_tree(c, cwd=cwd) for c in old_commits)
# if tree_unchanged:
# return new_tree
commit = commit_tree(new_tree, extant_old_commits + new_parents, message, cwd=cwd)
commit = commit_tree(new_tree, set(parent_commits), message, cwd=cwd)
for target_ref, old_commit in zip(target_refs, old_commits):
# update ref to point to commit, or create new ref
@ -204,41 +237,58 @@ def snap_ref(parent_refs: List[str],
return commit
def snap(parent_refs: Optional[List[str]] = None,
target_refs: Optional[List[str]] = None,
def snap(parent_refs: Optional[Sequence[str]] = None,
target_refs: Optional[Sequence[str]] = None,
message: Optional[str] = None,
*,
cwd: Optional[str] = None,
) -> str:
"""
Create a new commit of all non-ignored files in the repository.
Create a new commit, containing all non-ignored files.
`parent_refs` default to `['HEAD']`.
If there are any symbolic refs in `parent_refs`, the refs
they point to are added to <parent_refs>.
All commits pointed to by existing `parent_refs` and `target_refs`,
become parents of the newly created commit.
`target_refs` are created/updated to point the commit.
Args:
parent_refs: Refs in this list are set as parents of the new commit.
If any symbolic refs are included, the underlying refs they point
to are also added to `parent_refs`. Defaults to `['HEAD']`.
target_refs: Refs in this list will be updated to point to the new commit.
Default is
'refs/lethe/head_name' for each parent ref of the form
'refs/heads/head_name', and
'refs/lethe/path/to/ref' for each parent ref of the form
'refs/path/to/ref'.
`message` is used as the commit message.
- 'refs/lethe/LATEST', and
- 'refs/lethe/path/to/ref/LATEST' and
'refs/lethe/path/to/ref/snap_2020-12-20_18.21.14.281876'
for each parent_ref of the form 'refs/path/to/ref'.
Symbolic refs are dereferenced, so a parent_ref of 'master'
will results in the creation/overwrite of
'refs/lethe/heads/master/LATEST'
Note that 'refs/lethe/LATEST' must be specified explicitly if the default
is overridden
message: The commit message. Default is a simple note containing the current
date/time.
cwd: Path to the repository. Default is the current working directory.
Returns:
The hash for the new commit.
"""
if parent_refs is None:
parent_refs = ['HEAD']
else:
parent_refs = list(parent_refs)
parent_refs += [r for r in [deref_symref(s, cwd=cwd) for s in parent_refs] if r]
if target_refs is None:
target_refs = []
for p in parent_refs:
if p.startswith('refs/'):
p = p[len('refs/'):]
date_str = str(datetime.datetime.now())
date_ref = date_str.replace(' ', '_').replace(':', '.')
target_refs.append('refs/lethe/' + p)
if target_refs is None:
target_refs = ['refs/lethe/LATEST']
for pp in parent_refs:
if not pp.startswith('refs/'):
continue
target_base = 'refs/lethe/' + pp[len('refs/'):]
target_refs += [target_base + '/LATEST',
target_base + '/' + date_ref]
if message is None:
message = 'snapshot ' + date_str
commit = snap_ref(parent_refs, target_refs, message=message, cwd=cwd)
return commit