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| 1 | +# The MIT License (MIT) |
| 2 | +# Copyright (c) 2014 Microsoft Corporation |
| 3 | + |
| 4 | +# Permission is hereby granted, free of charge, to any person obtaining a copy |
| 5 | +# of this software and associated documentation files (the "Software"), to deal |
| 6 | +# in the Software without restriction, including without limitation the rights |
| 7 | +# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 8 | +# copies of the Software, and to permit persons to whom the Software is |
| 9 | +# furnished to do so, subject to the following conditions: |
| 10 | + |
| 11 | +# The above copyright notice and this permission notice shall be included in all |
| 12 | +# copies or substantial portions of the Software. |
| 13 | + |
| 14 | +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 15 | +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 16 | +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 17 | +# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 18 | +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 19 | +# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| 20 | +# SOFTWARE. |
| 21 | + |
| 22 | +"""Internal class for processing change feed implementation in the Azure Cosmos |
| 23 | +database service. |
| 24 | +""" |
| 25 | +import base64 |
| 26 | +import copy |
| 27 | +import json |
| 28 | +from abc import ABC, abstractmethod |
| 29 | + |
| 30 | +from azure.cosmos import http_constants, exceptions |
| 31 | +from azure.cosmos._change_feed.aio.change_feed_state import ChangeFeedStateV1, ChangeFeedStateV2 |
| 32 | +from azure.cosmos.aio import _retry_utility_async |
| 33 | +from azure.cosmos.exceptions import CosmosHttpResponseError |
| 34 | + |
| 35 | + |
| 36 | +class ChangeFeedFetcher(ABC): |
| 37 | + |
| 38 | + @abstractmethod |
| 39 | + async def fetch_next_block(self): |
| 40 | + pass |
| 41 | + |
| 42 | +class ChangeFeedFetcherV1(ChangeFeedFetcher): |
| 43 | + """Internal class for change feed fetch v1 implementation. |
| 44 | + This is used when partition key range id is used or when the supplied continuation token is in just simple etag. |
| 45 | + Please note v1 does not support split or merge. |
| 46 | +
|
| 47 | + """ |
| 48 | + def __init__( |
| 49 | + self, |
| 50 | + client, |
| 51 | + resource_link: str, |
| 52 | + feed_options: dict[str, any], |
| 53 | + fetch_function): |
| 54 | + |
| 55 | + self._client = client |
| 56 | + self._feed_options = feed_options |
| 57 | + |
| 58 | + self._change_feed_state = self._feed_options.pop("changeFeedState") |
| 59 | + if not isinstance(self._change_feed_state, ChangeFeedStateV1): |
| 60 | + raise ValueError(f"ChangeFeedFetcherV1 can not handle change feed state version {type(self._change_feed_state)}") |
| 61 | + self._change_feed_state.__class__ = ChangeFeedStateV1 |
| 62 | + |
| 63 | + self._resource_link = resource_link |
| 64 | + self._fetch_function = fetch_function |
| 65 | + |
| 66 | + async def fetch_next_block(self): |
| 67 | + """Returns a block of results. |
| 68 | +
|
| 69 | + :return: List of results. |
| 70 | + :rtype: list |
| 71 | + """ |
| 72 | + async def callback(): |
| 73 | + return await self.fetch_change_feed_items(self._fetch_function) |
| 74 | + |
| 75 | + return await _retry_utility_async.ExecuteAsync(self._client, self._client._global_endpoint_manager, callback) |
| 76 | + |
| 77 | + async def fetch_change_feed_items(self, fetch_function) -> list[dict[str, any]]: |
| 78 | + new_options = copy.deepcopy(self._feed_options) |
| 79 | + new_options["changeFeedState"] = self._change_feed_state |
| 80 | + |
| 81 | + self._change_feed_state.populate_feed_options(new_options) |
| 82 | + is_s_time_first_fetch = True |
| 83 | + while True: |
| 84 | + (fetched_items, response_headers) = await fetch_function(new_options) |
| 85 | + continuation_key = http_constants.HttpHeaders.ETag |
| 86 | + # In change feed queries, the continuation token is always populated. The hasNext() test is whether |
| 87 | + # there is any items in the response or not. |
| 88 | + # For start time however we get no initial results, so we need to pass continuation token? Is this true? |
| 89 | + self._change_feed_state.apply_server_response_continuation( |
| 90 | + response_headers.get(continuation_key)) |
| 91 | + |
| 92 | + if fetched_items: |
| 93 | + break |
| 94 | + elif is_s_time_first_fetch: |
| 95 | + is_s_time_first_fetch = False |
| 96 | + else: |
| 97 | + break |
| 98 | + return fetched_items |
| 99 | + |
| 100 | + |
| 101 | +class ChangeFeedFetcherV2(object): |
| 102 | + """Internal class for change feed fetch v2 implementation. |
| 103 | + """ |
| 104 | + |
| 105 | + def __init__( |
| 106 | + self, |
| 107 | + client, |
| 108 | + resource_link: str, |
| 109 | + feed_options: dict[str, any], |
| 110 | + fetch_function): |
| 111 | + |
| 112 | + self._client = client |
| 113 | + self._feed_options = feed_options |
| 114 | + |
| 115 | + self._change_feed_state = self._feed_options.pop("changeFeedState") |
| 116 | + if not isinstance(self._change_feed_state, ChangeFeedStateV2): |
| 117 | + raise ValueError(f"ChangeFeedFetcherV2 can not handle change feed state version {type(self._change_feed_state)}") |
| 118 | + self._change_feed_state.__class__ = ChangeFeedStateV2 |
| 119 | + |
| 120 | + self._resource_link = resource_link |
| 121 | + self._fetch_function = fetch_function |
| 122 | + |
| 123 | + async def fetch_next_block(self): |
| 124 | + """Returns a block of results. |
| 125 | +
|
| 126 | + :return: List of results. |
| 127 | + :rtype: list |
| 128 | + """ |
| 129 | + |
| 130 | + async def callback(): |
| 131 | + return await self.fetch_change_feed_items(self._fetch_function) |
| 132 | + |
| 133 | + try: |
| 134 | + return await _retry_utility_async.ExecuteAsync(self._client, self._client._global_endpoint_manager, callback) |
| 135 | + except CosmosHttpResponseError as e: |
| 136 | + if exceptions._partition_range_is_gone(e) or exceptions._is_partition_split_or_merge(e): |
| 137 | + # refresh change feed state |
| 138 | + await self._change_feed_state.handle_feed_range_gone(self._client._routing_map_provider, self._resource_link) |
| 139 | + else: |
| 140 | + raise e |
| 141 | + |
| 142 | + return await self.fetch_next_block() |
| 143 | + |
| 144 | + async def fetch_change_feed_items(self, fetch_function) -> list[dict[str, any]]: |
| 145 | + new_options = copy.deepcopy(self._feed_options) |
| 146 | + new_options["changeFeedState"] = self._change_feed_state |
| 147 | + |
| 148 | + self._change_feed_state.populate_feed_options(new_options) |
| 149 | + |
| 150 | + is_s_time_first_fetch = True |
| 151 | + while True: |
| 152 | + (fetched_items, response_headers) = await fetch_function(new_options) |
| 153 | + |
| 154 | + continuation_key = http_constants.HttpHeaders.ETag |
| 155 | + # In change feed queries, the continuation token is always populated. The hasNext() test is whether |
| 156 | + # there is any items in the response or not. |
| 157 | + # For start time however we get no initial results, so we need to pass continuation token? Is this true? |
| 158 | + if fetched_items: |
| 159 | + self._change_feed_state.apply_server_response_continuation( |
| 160 | + response_headers.get(continuation_key)) |
| 161 | + response_headers[continuation_key] = self._get_base64_encoded_continuation() |
| 162 | + break |
| 163 | + else: |
| 164 | + self._change_feed_state.apply_not_modified_response() |
| 165 | + self._change_feed_state.apply_server_response_continuation( |
| 166 | + response_headers.get(continuation_key)) |
| 167 | + response_headers[continuation_key] = self._get_base64_encoded_continuation() |
| 168 | + should_retry = self._change_feed_state.should_retry_on_not_modified_response() or is_s_time_first_fetch |
| 169 | + is_s_time_first_fetch = False |
| 170 | + if not should_retry: |
| 171 | + break |
| 172 | + |
| 173 | + return fetched_items |
| 174 | + |
| 175 | + def _get_base64_encoded_continuation(self) -> str: |
| 176 | + continuation_json = json.dumps(self._change_feed_state.to_dict()) |
| 177 | + json_bytes = continuation_json.encode('utf-8') |
| 178 | + # Encode the bytes to a Base64 string |
| 179 | + base64_bytes = base64.b64encode(json_bytes) |
| 180 | + # Convert the Base64 bytes to a string |
| 181 | + return base64_bytes.decode('utf-8') |
| 182 | + |
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