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db.py
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# Copyright (C) 2015 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
import binascii
import functools
import psycopg2
import tempfile
from contextlib import contextmanager
TMP_CONTENT_TABLE = 'tmp_content'
def stored_procedure(stored_proc):
"""decorator to execute remote stored procedure, specified as argument
Generally, the body of the decorated function should be empty. If it is
not, the stored procedure will be executed first; the function body then.
"""
def wrap(meth):
@functools.wraps(meth)
def _meth(self, *args, **kwargs):
cur = kwargs.get('cur', None)
self._cursor(cur).execute('SELECT %s()' % stored_proc)
meth(self, *args, **kwargs)
return _meth
return wrap
def entry_to_bytes(entry):
"""Convert an entry coming from the database to bytes"""
if isinstance(entry, memoryview):
return entry.tobytes()
return entry
def line_to_bytes(line):
"""Convert a line coming from the database to bytes"""
return line.__class__(entry_to_bytes(entry) for entry in line)
def cursor_to_bytes(cursor):
"""Yield all the data from a cursor as bytes"""
yield from (line_to_bytes(line) for line in cursor)
class Db:
"""Proxy to the SWH DB, with wrappers around stored procedures
"""
@classmethod
def connect(cls, *args, **kwargs):
"""factory method to create a DB proxy
Accepts all arguments of psycopg2.connect; only some specific
possibilities are reported below.
Args:
connstring: libpq2 connection string
"""
conn = psycopg2.connect(*args, **kwargs)
return cls(conn)
def _cursor(self, cur_arg):
"""get a cursor: from cur_arg if given, or a fresh one otherwise
meant to avoid boilerplate if/then/else in methods that proxy stored
procedures
"""
if cur_arg is not None:
return cur_arg
# elif self.cur is not None:
# return self.cur
else:
return self.conn.cursor()
def __init__(self, conn):
"""create a DB proxy
Args:
conn: psycopg2 connection to the SWH DB
"""
self.conn = conn
@contextmanager
def transaction(self):
"""context manager to execute within a DB transaction
Yields:
a psycopg2 cursor
"""
with self.conn.cursor() as cur:
try:
yield cur
self.conn.commit()
except:
if not self.conn.closed:
self.conn.rollback()
raise
def mktemp(self, tblname, cur=None):
self._cursor(cur).execute('SELECT swh_mktemp(%s)', (tblname,))
def mktemp_dir_entry(self, entry_type, cur=None):
self._cursor(cur).execute('SELECT swh_mktemp_dir_entry(%s)',
(('directory_entry_%s' % entry_type),))
@stored_procedure('swh_mktemp_revision')
def mktemp_revision(self, cur=None): pass
@stored_procedure('swh_mktemp_release')
def mktemp_release(self, cur=None): pass
def copy_to(self, items, tblname, columns, cur=None, item_cb=None):
def escape(data):
if data is None:
return ''
if isinstance(data, bytes):
return '\\x%s' % binascii.hexlify(data).decode('ascii')
elif isinstance(data, str):
return '"%s"' % data.replace('"', '""')
else:
return str(data)
with tempfile.TemporaryFile('w+') as f:
for d in items:
if item_cb is not None:
item_cb(d)
line = [escape(d.get(k)) for k in columns]
f.write(','.join(line))
f.write('\n')
f.seek(0)
self._cursor(cur).copy_expert('COPY %s (%s) FROM STDIN CSV' % (
tblname, ', '.join(columns)), f)
@stored_procedure('swh_content_add')
def content_add_from_temp(self, cur=None): pass
@stored_procedure('swh_skipped_content_add')
def skipped_content_add_from_temp(self, cur=None): pass
@stored_procedure('swh_revision_add')
def revision_add_from_temp(self, cur=None): pass
@stored_procedure('swh_release_add')
def release_add_from_temp(self, cur=None): pass
def content_missing_from_temp(self, cur=None):
cur = self._cursor(cur)
cur.execute("""SELECT sha1, sha1_git, sha256
FROM swh_content_missing()""")
yield from cursor_to_bytes(cur)
def skipped_content_missing_from_temp(self, cur=None):
cur = self._cursor(cur)
cur.execute("""SELECT sha1, sha1_git, sha256
FROM swh_skipped_content_missing()""")
yield from cursor_to_bytes(cur)
def content_find(self, sha1=None, sha1_git=None, sha256=None, cur=None):
"""Find the content optionally on a combination of the following
checksums sha1, sha1_git or sha256.
Args:
sha1: sha1 content
git_sha1: the sha1 computed `a la git` sha1 of the content
sha256: sha256 content
Returns:
The content if found or null.
"""
cur = self._cursor(cur)
cur.execute("""SELECT sha1, sha1_git, sha256
FROM swh_content_find(%s, %s, %s)
LIMIT 1""", (sha1, sha1_git, sha256))
yield from cursor_to_bytes(cur)
def directory_missing_from_temp(self, cur=None):
cur = self._cursor(cur)
cur.execute('SELECT * FROM swh_directory_missing()')
yield from cursor_to_bytes(cur)
def directory_walk_one(self, directory, cur=None):
cur = self._cursor(cur)
cur.execute('SELECT * FROM swh_directory_walk_one(%s)', (directory,))
yield from cursor_to_bytes(cur)
def revision_missing_from_temp(self, cur=None):
cur = self._cursor(cur)
cur.execute('SELECT id FROM swh_revision_missing() as r(id)')
yield from cursor_to_bytes(cur)
def release_missing_from_temp(self, cur=None):
cur = self._cursor(cur)
cur.execute('SELECT id FROM swh_release_missing() as r(id)')
yield from cursor_to_bytes(cur)

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