[#201] Implement fetch() in the DAS API

CHANGELOG

@@ -1 +1 @@
-
+[#201] Implement fetch() in the DAS API

hyperon_das/cache.py

@@ -2,12 +2,40 @@
 from collections import deque
 from itertools import product
 from threading import Semaphore, Thread
-from typing import Any, Dict, List, Optional, Union
+from typing import Any, Dict, List, Optional, TypeVar, Union
 
 from hyperon_das_atomdb import WILDCARD
+from hyperon_das_atomdb.adapters import InMemoryDB, RedisMongoDB
 
+from hyperon_das.client import FunctionsClient
 from hyperon_das.utils import Assignment, QueryAnswer
 
+AdapterDBType = TypeVar("AdapterDBType", RedisMongoDB, InMemoryDB)
+
+
+class CacheManager:
+    def __init__(self, cache: AdapterDBType, **kwargs):
+        self.cache = cache
+
+    def fetch_data(
+        self,
+        query: Union[List[dict], dict],
+        host: Optional[str] = None,
+        port: Optional[int] = None,
+        **kwargs,
+    ) -> List[Dict[str, Any]]:
+        try:
+            if not (server := kwargs.pop('server', None)):
+                server = FunctionsClient(host, port)
+            return server.fetch(query=query, **kwargs)
+        except Exception as e:
+            # TODO: Map possible errors
+            raise e
+
+    def bulk_insert(self, documents: Dict[str, Any]) -> None:
+        """insert statements in "bulk", not returning rows"""
+        self.cache.bulk_insert(documents)
+
 
 class QueryAnswerIterator(ABC):
     def __init__(self, source: Any):

hyperon_das/client.py

@@ -7,14 +7,18 @@
 
 from hyperon_das.exceptions import ConnectionError, HTTPError, RequestError, TimeoutError
 from hyperon_das.logger import logger
-from hyperon_das.utils import deserialize, serialize
+from hyperon_das.utils import connect_to_server, deserialize, serialize
 
 
 class FunctionsClient:
-    def __init__(self, url: str, server_count: int = 0, name: Optional[str] = None):
+    def __init__(self, host: str, port: int, server_count: int = 0, name: Optional[str] = None):
+        if not host:
+            raise ValueError('Host is required')
+
+        self.url = connect_to_server(host, port)
+
         if not name:
             self.name = f'server-{server_count}'
-        self.url = url
 
     def _send_request(self, payload) -> Any:
         try:
@@ -177,3 +181,16 @@ def custom_query(self, index_id: str, **kwargs) -> List[Dict[str, Any]]:
             'input': {'index_id': index_id, 'kwargs': kwargs},
         }
         return self._send_request(payload)
+
+    def fetch(
+        self,
+        query: Union[List[dict], dict],
+        host: Optional[str] = None,
+        port: Optional[int] = None,
+        **kwargs,
+    ) -> Any:
+        payload = {
+            'action': 'fetch',
+            'input': {'query': query, 'host': host, 'port': port, 'kwargs': kwargs},
+        }
+        return self._send_request(payload)

hyperon_das/das.py

@@ -4,7 +4,7 @@
 from hyperon_das_atomdb.adapters import InMemoryDB, RedisMongoDB
 from hyperon_das_atomdb.exceptions import InvalidAtomDB
 
-from hyperon_das.cache import QueryAnswerIterator
+from hyperon_das.cache import CacheManager, QueryAnswerIterator
 from hyperon_das.exceptions import (
     GetTraversalCursorException,
     InvalidDASParameters,
@@ -32,6 +32,8 @@ def __init__(self, **kwargs: Optional[Dict[str, Any]]) -> None:
         else:
             raise InvalidAtomDB(message="Invalid AtomDB type. Choose either 'ram' or 'redis_mongo'")
 
+        kwargs.update({'cache_manager': CacheManager(self.backend)})
+
         if query_engine_parameter == 'local':
             self.query_engine = LocalQueryEngine(self.backend, kwargs)
             logger().info('Initialized local Das')
@@ -575,3 +577,44 @@ def create_field_index(
         return self.query_engine.create_field_index(
             atom_type, field, type=type, composite_type=composite_type
         )
+
+    def fetch(
+        self,
+        query: Union[List[dict], dict],
+        host: Optional[str] = None,
+        port: Optional[int] = None,
+        **kwargs,
+    ) -> Any:
+        """Fetch data from the remote server using the a query as input and load it locally.
+        If it is a local DAS, the host and port must be sent.
+
+        The input dict is a link, used as a pattern to make the query.
+        Variables can be used as link targets as well as nodes. Nested links are
+        allowed as well.
+
+        Args:
+            query (Union[List[dict], dict]): A pattern described as a link (possibly with nested links)
+                with nodes and variables used to query the knowledge base.
+            host (Optional[str], optional): Address to remote server. Defaults to None.
+            port (Optional[int], optional): Port to remote server. Defaults to None.
+
+        Raises:
+            ValueError: If the 'host' and 'port' parameters are not sent to DAS local
+
+        Examples:
+            >>> query = {
+                    "atom_type": "link",
+                    "type": "Expression",
+                    "targets": [
+                        {"atom_type": "node", "type": "Symbol", "name": "Inheritance"},
+                        {"atom_type": "variable", "name": "v1"},
+                        {"atom_type": "node", "type": "Symbol", "name": '"mammal"'},
+                    ],
+                }
+                das = DistributedAtomSpace()
+                das.fetch(query, host='123.4.5.6', port=8080)
+        """
+        if not kwargs.get('running_on_server') and not host and not port:
+            raise ValueError("The 'host' and 'port' parameters must be sent to DAS local")
+
+        return self.query_engine.fetch(query, host, port, **kwargs)

hyperon_das/decorators.py

@@ -1,5 +1,6 @@
 import time
 from functools import wraps
+from http import HTTPStatus  # noqa: F401
 from typing import Callable
 
 from hyperon_das.exceptions import ConnectionError
@@ -17,9 +18,9 @@ def wrapper(*args, **kwargs):
             while retry_count < attempts and timer_count < timeout_seconds:
                 try:
                     start_time = time.time()
-                    response = function(*args, **kwargs)
+                    status, response = function(*args, **kwargs)
                     end_time = time.time()
-                    if response is not None:
+                    if status == HTTPStatus.OK:
                         logger().debug(
                             f'{retry_count + 1} successful connection attempt at [host={args[1]}]'
                         )
@@ -34,9 +35,9 @@ def wrapper(*args, **kwargs):
                     time.sleep(waiting_time_seconds)
                     retry_count += 1
                     timer_count += end_time - start_time
-            port = f':{args[2]}' if args[2] else ''
+            port = f':{args[1]}' if len(args) > 1 else ''
             message = (
-                f'Failed to connect to remote Das {args[1]}'
+                f'Failed to connect to remote Das {args[0]}'
                 + port
                 + f' - attempts:{retry_count} - time_attempted: {timer_count}'
             )