apdbCassandraReplica.py

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# This file is part of dax_apdb.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (http://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
from __future__ import annotations
 
__all__ = ["ApdbCassandraReplica"]
 
import logging
from collections.abc import Iterable
from typing import TYPE_CHECKING, Any, cast
 
import astropy.time
from lsst.utils.iteration import chunk_iterable
 
from ..apdbReplica import ApdbReplica, ApdbTableData, ReplicaChunk
from ..timer import Timer
from ..versionTuple import VersionTuple
from .apdbCassandraSchema import ApdbCassandraSchema, ExtraTables
from .cassandra_utils import ApdbCassandraTableData, PreparedStatementCache
 
if TYPE_CHECKING:
    from .apdbCassandra import ApdbCassandra
 
_LOG = logging.getLogger(__name__)
 
VERSION = VersionTuple(1, 0, 0)
"""Version for the code controlling replication tables. This needs to be
updated following compatibility rules when schema produced by this code
changes.
"""
 
 
class ApdbCassandraReplica(ApdbReplica):
    """Implementation of `ApdbReplica` for Cassandra backend.
 
    Parameters
    ----------
    apdb : `ApdbCassandra`
        Instance of ApbdCassandra for database.
    schema : `ApdbCassandraSchema`
        Instance of ApdbCassandraSchema for database.
    session
        Instance of cassandra session type.
    """
 
    def __init__(self, apdb: ApdbCassandra, schema: ApdbCassandraSchema, session: Any):
        # Note that ApdbCassandra instance must stay alive while this object
        # exists, so we keep reference to it.
        self._apdb = apdb
        self._schema = schema
        self._session = session
        self._config = apdb.config
 
        # Cache for prepared statements
        self._preparer = PreparedStatementCache(self._session)
 
    @classmethod
    def apdbReplicaImplementationVersion(cls) -> VersionTuple:
        # Docstring inherited from base class.
        return VERSION
 
    def getReplicaChunks(self) -> list[ReplicaChunk] | None:
        # docstring is inherited from a base class
        if not self._schema.has_replica_chunks:
            return None
 
        # everything goes into a single partition
        partition = 0
 
        table_name = self._schema.tableName(ExtraTables.ApdbReplicaChunks)
        # We want to avoid timezone mess so return timestamps as milliseconds.
        query = (
            "SELECT toUnixTimestamp(last_update_time), apdb_replica_chunk, unique_id "
            f'FROM "{self._config.keyspace}"."{table_name}" WHERE partition = ?'
        )
 
        result = self._session.execute(
            self._preparer.prepare(query),
            (partition,),
            timeout=self._config.read_timeout,
            execution_profile="read_tuples",
        )
        # order by last_update_time
        rows = sorted(result)
        return [
            ReplicaChunk(
                id=row[1],
                last_update_time=astropy.time.Time(row[0] / 1000, format="unix_tai"),
                unique_id=row[2],
            )
            for row in rows
        ]
 
    def deleteReplicaChunks(self, chunks: Iterable[int]) -> None:
        # docstring is inherited from a base class
        if not self._schema.has_replica_chunks:
            raise ValueError("APDB is not configured for replication")
 
        # There is 64k limit on number of markers in Cassandra CQL
        for chunk_ids in chunk_iterable(chunks, 20_000):
            params = ",".join("?" * len(chunk_ids))
 
            # everything goes into a single partition
            partition = 0
 
            table_name = self._schema.tableName(ExtraTables.ApdbReplicaChunks)
            query = (
                f'DELETE FROM "{self._config.keyspace}"."{table_name}" '
                f"WHERE partition = ? AND apdb_replica_chunk IN ({params})"
            )
 
            self._session.execute(
                self._preparer.prepare(query),
                [partition] + list(chunk_ids),
                timeout=self._config.remove_timeout,
            )
 
            # Also remove those chunk_ids from Dia*Chunks tables.
            for table in (
                ExtraTables.DiaObjectChunks,
                ExtraTables.DiaSourceChunks,
                ExtraTables.DiaForcedSourceChunks,
            ):
                table_name = self._schema.tableName(table)
                query = (
                    f'DELETE FROM "{self._config.keyspace}"."{table_name}"'
                    f" WHERE apdb_replica_chunk IN ({params})"
                )
                self._session.execute(
                    self._preparer.prepare(query),
                    chunk_ids,
                    timeout=self._config.remove_timeout,
                )
 
    def getDiaObjectsChunks(self, chunks: Iterable[int]) -> ApdbTableData:
        # docstring is inherited from a base class
        return self._get_chunks(ExtraTables.DiaObjectChunks, chunks)
 
    def getDiaSourcesChunks(self, chunks: Iterable[int]) -> ApdbTableData:
        # docstring is inherited from a base class
        return self._get_chunks(ExtraTables.DiaSourceChunks, chunks)
 
    def getDiaForcedSourcesChunks(self, chunks: Iterable[int]) -> ApdbTableData:
        # docstring is inherited from a base class
        return self._get_chunks(ExtraTables.DiaForcedSourceChunks, chunks)
 
    def _get_chunks(self, table: ExtraTables, chunks: Iterable[int]) -> ApdbTableData:
        """Return records from a particular table given set of insert IDs."""
        if not self._schema.has_replica_chunks:
            raise ValueError("APDB is not configured for replication")
 
        # We do not expect too may chunks in this query.
        chunks = list(chunks)
        params = ",".join("?" * len(chunks))
 
        table_name = self._schema.tableName(table)
        # I know that chunk table schema has only regular APDB columns plus
        # apdb_replica_chunk column, and this is exactly what we need to return
        # from this method, so selecting a star is fine here.
        query = (
            f'SELECT * FROM "{self._config.keyspace}"."{table_name}" WHERE apdb_replica_chunk IN ({params})'
        )
        statement = self._preparer.prepare(query)
 
        with Timer(f"{table_name} select chunk", self._config.timer):
            result = self._session.execute(statement, chunks, execution_profile="read_raw")
            table_data = cast(ApdbCassandraTableData, result._current_rows)
        return table_data