GraphStorageClient.py

#!/usr/bin/env python
# --coding:utf-8--
 
# Copyright (c) 2020 vesoft inc. All rights reserved.
#
# This source code is licensed under Apache 2.0 License.
 
 
"""
The client to scan vertex and edge from storage,
the return data is from thr graph database
"""
import sys
 
from nebula3.sclient.ScanResult import ScanResult
from nebula3.sclient.net import GraphStorageConnection
from nebula3.storage.ttypes import (
    ScanCursor,
    ScanEdgeRequest,
    ScanVertexRequest,
    VertexProp,
    EdgeProp,
)
from nebula3.logger import logger
 
kVid = b'_vid'
kSrc = b'_src'
kType = b'_type'
kRank = b'_rank'
kDst = b'_dst'
 
 
class GraphStorageClient(object):
    DEFAULT_START_TIME = 0
    DEFAULT_END_TIME = sys.maxsize
    DEFAULT_LIMIT = 1000
 
    def __init__(self, meta_cache, storage_addrs=None, time_out=60000):
        self._meta_cache_meta_cache = meta_cache
        self._storage_addrs_storage_addrs = storage_addrs
        self._time_out_time_out = time_out
        self._connections_connections = []
        self._create_connection_create_connection()
 
    def get_conns(self):
        """get all connections which connect to storaged, the ScanResult use it
 
        :return: list<GraphStorageConnection>
        """
        return self._connections_connections
 
    def __del__(self):
        self.closeclose()
 
    def close(self):
        """close the GraphStorageClient
 
        :return:
        """
        try:
            for conn in self._connections_connections:
                conn.close()
        except Exception as e:
            logger.error('Close connection failed: {}'.format(e))
            raise
 
    def _create_connection(self):
        """create GraphStorageConnection
 
        :return: GraphStorageConnection
        """
        if self._storage_addrs_storage_addrs is None:
            self._storage_addrs_storage_addrs = self._meta_cache_meta_cache.get_all_storage_addrs()
        if len(self._storage_addrs_storage_addrs) == 0:
            raise RuntimeError('Get storage address from meta cache is empty')
        try:
            for addr in self._storage_addrs_storage_addrs:
                conn = GraphStorageConnection(addr, self._time_out_time_out, self._meta_cache_meta_cache)
                conn.open()
                self._connections_connections.append(conn)
        except Exception as e:
            logger.error('Create storage connection failed: {}'.format(e))
            raise
 
    def get_space_addrs(self, space_name):
        """get all storage addresses that manage space
 
        :param space_name: the specified space name
        :return: list<(ip, port)>
        """
        return self.meta_cache.get_space_addrs(space_name)
 
    def scan_vertex(
        self,
        space_name,
        tag_name,
        prop_names=[],
        limit=DEFAULT_LIMIT,
        start_time=DEFAULT_START_TIME,
        end_time=DEFAULT_END_TIME,
        where=None,
        only_latest_version=False,
        enable_read_from_follower=True,
        partial_success=False,
    ):
        """scan vertex with the specified space_name, tag_name,
        if the prop_names is empty, will return all properties of the tag
 
        :param prop_names: if given empty, return all property
        :param tag_name: the tag name
        :param space_name: the space name
        :param limit: the max vertex number from one storaged
        :param start_time: the min version of vertex
        :param end_time: the max version of vertex
        :param where: now is unsupported
        :param only_latest_version: when storage enable multi versions and only_latest_version is true,
        only return latest version.
        when storage disable multi versions, just use the default value.
        :param enable_read_from_follower: if set to false, forbid follower read
        :param partial_success: if set true, when partial success, it will continue until finish
        :return: ScanResult
        """
        part_leaders = self._meta_cache_meta_cache.get_part_leaders(space_name)
        return self._scan_vertex_scan_vertex(
            space_name,
            part_leaders,
            tag_name,
            prop_names,
            limit,
            start_time,
            end_time,
            where,
            only_latest_version,
            enable_read_from_follower,
            partial_success,
        )
 
    def scan_vertex_with_part(
        self,
        space_name,
        part,
        tag_name,
        prop_names=[],
        limit=DEFAULT_LIMIT,
        start_time=DEFAULT_START_TIME,
        end_time=DEFAULT_END_TIME,
        where=None,
        only_latest_version=False,
        enable_read_from_follower=True,
        partial_success=False,
    ):
        """scan vertex with the specified space_name, partId, tag_name,
        if the prop_names is empty, will return all properties of the tag
 
        :param prop_names: if given empty, return all property
        :param tag_name: the tag name
        :type part: part id
        :param space_name: the space name
        :param limit: the max vertex number from one storaged
        :param start_time: the min version of vertex
        :param end_time: the max version of vertex
        :param where: now is unsupported
        :param only_latest_version: when storage enable multi versions and only_latest_version is true,
        only return latest version.
        when storage disable multi versions, just use the default value.
        :param enable_read_from_follower: if set to false, forbid follower read
        :param partial_success: if set true, when partial success, it will continue until finish
        :return: ScanResult
        """
 
        part_leaders = {part: self._meta_cache_meta_cache.get_part_leader(space_name, part)}
        return self._scan_vertex_scan_vertex(
            space_name,
            part_leaders,
            tag_name,
            prop_names,
            limit,
            start_time,
            end_time,
            where,
            only_latest_version,
            enable_read_from_follower,
            partial_success,
        )
 
    def _scan_vertex(
        self,
        space_name,
        part_leaders,
        tag_name,
        prop_names,
        limit,
        start_time,
        end_time,
        where,
        only_latest_version,
        enable_read_from_follower,
        partial_success=False,
    ):
        space_id = self._meta_cache_meta_cache.get_space_id(space_name)
        tag_id = self._meta_cache_meta_cache.get_tag_id(space_name, tag_name)
        vertex_prop: VertexProp = VertexProp()
        vertex_prop.tag = tag_id
        vertex_prop.props = [kVid]
        for prop_name in prop_names:
            vertex_prop.props.append(prop_name.encode('utf-8'))
 
        if len(prop_names) == 0:
            schema = self._meta_cache_meta_cache.get_tag_schema(space_name, tag_name)
            for col in schema.columns:
                vertex_prop.props.append(col.name)
 
        parts = {}
        for id in part_leaders.keys():
            parts[id] = ScanCursor()
 
        # construct request
        req = ScanVertexRequest()
        req.space_id = space_id
        req.parts = parts
        req.return_columns = [vertex_prop]
        req.limit = limit
        req.start_time = start_time
        req.end_time = end_time
        req.filter = where
        req.only_latest_version = only_latest_version
        req.enable_read_from_follower = enable_read_from_follower
        return ScanResult(
            self,
            req=req,
            part_addrs=part_leaders,
            is_vertex=True,
            partial_success=partial_success,
        )
 
    def scan_edge(
        self,
        space_name,
        edge_name,
        prop_names=[],
        limit=DEFAULT_LIMIT,
        start_time=DEFAULT_START_TIME,
        end_time=DEFAULT_END_TIME,
        where=None,
        only_latest_version=False,
        enable_read_from_follower=True,
        partial_success=False,
    ):
        """scan edge with the specified space_name, edge_name,
        if the prop_names is empty, will return all properties of the edge
 
        :param prop_names: if given empty, return all property
        :param edge_name: the edge name
        :param space_name: the space name
        :param limit: the max vertex number from one storaged
        :param start_time: the min version of vertex
        :param end_time: the max version of vertex
        :param where: now is unsupported
        :param only_latest_version: when storage enable multi versions and only_latest_version is true,
        only return latest version.
        when storage disable multi versions, just use the default value.
        :param enable_read_from_follower: if set to false, forbid follower read
        :param partial_success: if set true, when partial success, it will continue until finish
        :return: ScanResult
        """
        part_leaders = self._meta_cache_meta_cache.get_part_leaders(space_name)
        return self._scan_edge_scan_edge(
            space_name,
            part_leaders,
            edge_name,
            prop_names,
            limit,
            start_time,
            end_time,
            where,
            only_latest_version,
            enable_read_from_follower,
            partial_success,
        )
 
    def scan_edge_with_part(
        self,
        space_name,
        part,
        edge_name,
        prop_names=[],
        limit=DEFAULT_LIMIT,
        start_time=DEFAULT_START_TIME,
        end_time=DEFAULT_END_TIME,
        where=None,
        only_latest_version=False,
        enable_read_from_follower=True,
        partial_success=False,
    ):
        """scan edge with the specified space_name, partId, edge_name,
        if the prop_names is empty, will return all properties of the edge
 
        :param space_name: the space name
        :param part: the partition num of the given space
        :type prop_names: if given empty, return all property
        :param edge_name: the edge name
        :param limit: the max vertex number from one storaged
        :param start_time: the min version of edge
        :param end_time: the max version of edge
        :param where: now is unsupported
        :param only_latest_version: when storage enable multi versions and only_latest_version is true,
        only return latest version.
        when storage disable multi versions, just use the default value.
        :param enable_read_from_follower: if set to false, forbid follower read
        :param partial_success: if set true, when partial success, it will continue until finish
        :return: ScanResult
        """
        part_leaders = {part: self._meta_cache_meta_cache.get_part_leader(space_name, part)}
        return self._scan_edge_scan_edge(
            space_name,
            part_leaders,
            edge_name,
            prop_names,
            limit,
            start_time,
            end_time,
            where,
            only_latest_version,
            enable_read_from_follower,
            partial_success,
        )
 
    def _scan_edge(
        self,
        space_name,
        part_leaders,
        edge_name,
        prop_names,
        limit,
        start_time,
        end_time,
        where,
        only_latest_version,
        enable_read_from_follower,
        partial_success,
    ):
        space_id = self._meta_cache_meta_cache.get_space_id(space_name)
        edge_type = self._meta_cache_meta_cache.get_edge_type(space_name, edge_name)
        edge_prop = EdgeProp()
        edge_prop.type = edge_type
        edge_prop.props = [kSrc, kType, kRank, kDst]
 
        for prop_name in prop_names:
            edge_prop.props.append(prop_name.encode('utf-8'))
 
        # When storage return column names, here need delete
        if len(prop_names) == 0:
            schema = self._meta_cache_meta_cache.get_edge_schema(space_name, edge_name)
            for col in schema.columns:
                edge_prop.props.append(col.name)
 
        parts = {}
        for id in part_leaders.keys():
            parts[id] = ScanCursor()
 
        req = ScanEdgeRequest()
        req.space_id = space_id
        req.parts = parts
        req.return_columns = [edge_prop]
        req.limit = limit
        req.start_time = start_time
        req.end_time = end_time
        req.filter = where
        req.only_latest_version = only_latest_version
        req.enable_read_from_follower = enable_read_from_follower
        return ScanResult(
            self,
            req=req,
            part_addrs=part_leaders,
            is_vertex=False,
            partial_success=partial_success,
        )