feat: cache package search results with Redis

The queries being done on the package search page are quite costly.
(Especially the default one ordered by "Popularity" when navigating to /packages)

Let's add the search results to the Redis cache:
Every result of a search query is being pushed to Redis until we hit our maximum of 50k.
An entry expires after 3 minutes before it's evicted from the cache.
Lifetime an Max values are configurable.

Signed-off-by: moson-mo <mo-son@mailbox.org>

aurweb/cache.py

@@ -1,21 +1,43 @@
-from redis import Redis
+import pickle
+
 from sqlalchemy import orm
 
+from aurweb import config
+from aurweb.aur_redis import redis_connection
 
-async def db_count_cache(
+_redis = redis_connection()
-    redis: Redis, key: str, query: orm.Query, expire: int = None
+
-) -> int:
+
+async def db_count_cache(key: str, query: orm.Query, expire: int = None) -> int:
     """Store and retrieve a query.count() via redis cache.
 
-    :param redis: Redis handle
     :param key: Redis key
     :param query: SQLAlchemy ORM query
     :param expire: Optional expiration in seconds
     :return: query.count()
     """
-    result = redis.get(key)
+    result = _redis.get(key)
     if result is None:
-        redis.set(key, (result := int(query.count())))
+        _redis.set(key, (result := int(query.count())))
         if expire:
-            redis.expire(key, expire)
+            _redis.expire(key, expire)
     return int(result)
+
+
+async def db_query_cache(key: str, query: orm.Query, expire: int = None):
+    """Store and retrieve query results via redis cache.
+
+    :param key: Redis key
+    :param query: SQLAlchemy ORM query
+    :param expire: Optional expiration in seconds
+    :return: query.all()
+    """
+    result = _redis.get(key)
+    if result is None:
+        if _redis.dbsize() > config.getint("cache", "max_search_entries", 50000):
+            return query.all()
+        _redis.set(key, (result := pickle.dumps(query.all())), ex=expire)
+        if expire:
+            _redis.expire(key, expire)
+
+    return pickle.loads(result)

aurweb/routers/html.py

@@ -89,22 +89,20 @@ async def index(request: Request):
 
     bases = db.query(models.PackageBase)
 
-    redis = aurweb.aur_redis.redis_connection()
+    cache_expire = aurweb.config.getint("cache", "expiry_time")
-    cache_expire = 300  # Five minutes.
-
     # Package statistics.
     context["package_count"] = await db_count_cache(
-        redis, "package_count", bases, expire=cache_expire
+        "package_count", bases, expire=cache_expire
     )
 
     query = bases.filter(models.PackageBase.MaintainerUID.is_(None))
     context["orphan_count"] = await db_count_cache(
-        redis, "orphan_count", query, expire=cache_expire
+        "orphan_count", query, expire=cache_expire
     )
 
     query = db.query(models.User)
     context["user_count"] = await db_count_cache(
-        redis, "user_count", query, expire=cache_expire
+        "user_count", query, expire=cache_expire
     )
 
     query = query.filter(
@@ -114,7 +112,7 @@ async def index(request: Request):
         )
     )
     context["trusted_user_count"] = await db_count_cache(
-        redis, "trusted_user_count", query, expire=cache_expire
+        "trusted_user_count", query, expire=cache_expire
     )
 
     # Current timestamp.
@@ -130,26 +128,26 @@ async def index(request: Request):
 
     query = bases.filter(models.PackageBase.SubmittedTS >= seven_days_ago)
     context["seven_days_old_added"] = await db_count_cache(
-        redis, "seven_days_old_added", query, expire=cache_expire
+        "seven_days_old_added", query, expire=cache_expire
     )
 
     query = updated.filter(models.PackageBase.ModifiedTS >= seven_days_ago)
     context["seven_days_old_updated"] = await db_count_cache(
-        redis, "seven_days_old_updated", query, expire=cache_expire
+        "seven_days_old_updated", query, expire=cache_expire
     )
 
     year = seven_days * 52  # Fifty two weeks worth: one year.
     year_ago = now - year
     query = updated.filter(models.PackageBase.ModifiedTS >= year_ago)
     context["year_old_updated"] = await db_count_cache(
-        redis, "year_old_updated", query, expire=cache_expire
+        "year_old_updated", query, expire=cache_expire
     )
 
     query = bases.filter(
         models.PackageBase.ModifiedTS - models.PackageBase.SubmittedTS < 3600
     )
     context["never_updated"] = await db_count_cache(
-        redis, "never_updated", query, expire=cache_expire
+        "never_updated", query, expire=cache_expire
     )
 
     # Get the 15 most recently updated packages.

aurweb/routers/packages.py

@@ -7,6 +7,7 @@ from fastapi import APIRouter, Form, Query, Request, Response
 import aurweb.filters  # noqa: F401
 from aurweb import aur_logging, config, db, defaults, models, util
 from aurweb.auth import creds, requires_auth
+from aurweb.cache import db_count_cache, db_query_cache
 from aurweb.exceptions import InvariantError, handle_form_exceptions
 from aurweb.models.relation_type import CONFLICTS_ID, PROVIDES_ID, REPLACES_ID
 from aurweb.packages import util as pkgutil
@@ -14,6 +15,7 @@ from aurweb.packages.search import PackageSearch
 from aurweb.packages.util import get_pkg_or_base
 from aurweb.pkgbase import actions as pkgbase_actions, util as pkgbaseutil
 from aurweb.templates import make_context, make_variable_context, render_template
+from aurweb.util import hash_query
 
 logger = aur_logging.get_logger(__name__)
 router = APIRouter()
@@ -87,7 +89,11 @@ async def packages_get(
     # Collect search result count here; we've applied our keywords.
     # Including more query operations below, like ordering, will
     # increase the amount of time required to collect a count.
-    num_packages = search.count()
+    # we use redis for caching the results of the query
+    cache_expire = config.getint("cache", "expiry_time")
+    num_packages = await db_count_cache(
+        hash_query(search.query), search.query, cache_expire
+    )
 
     # Apply user-specified sort column and ordering.
     search.sort_by(sort_by, sort_order)
@@ -108,7 +114,12 @@ async def packages_get(
         models.PackageNotification.PackageBaseID.label("Notify"),
     )
 
-    packages = results.limit(per_page).offset(offset)
+    # paging
+    results = results.limit(per_page).offset(offset)
+
+    # we use redis for caching the results of the query
+    packages = await db_query_cache(hash_query(results), results, cache_expire)
+
     context["packages"] = packages
     context["packages_count"] = num_packages
 

aurweb/util.py

@@ -4,6 +4,7 @@ import secrets
 import shlex
 import string
 from datetime import datetime
+from hashlib import sha1
 from http import HTTPStatus
 from subprocess import PIPE, Popen
 from typing import Callable, Iterable, Tuple, Union
@@ -13,6 +14,7 @@ import fastapi
 import pygit2
 from email_validator import EmailSyntaxError, validate_email
 from fastapi.responses import JSONResponse
+from sqlalchemy.orm import Query
 
 import aurweb.config
 from aurweb import aur_logging, defaults
@@ -200,3 +202,9 @@ def shell_exec(cmdline: str, cwd: str) -> Tuple[int, str, str]:
     proc = Popen(args, cwd=cwd, stdout=PIPE, stderr=PIPE)
     out, err = proc.communicate()
     return proc.returncode, out.decode().strip(), err.decode().strip()
+
+
+def hash_query(query: Query):
+    return sha1(
+        str(query.statement.compile(compile_kwargs={"literal_binds": True})).encode()
+    ).hexdigest()

conf/config.defaults

@@ -165,3 +165,9 @@ commit_url = https://gitlab.archlinux.org/archlinux/aurweb/-/commits/%s
 ; voted on based on `now + range_start <= End <= now + range_end`.
 range_start = 500
 range_end = 172800
+
+[cache]
+; maximum number of keys/entries (for search results) in our redis cache, default is 50000
+max_search_entries = 50000
+; number of seconds after a cache entry expires, default is 3 minutes
+expiry_time = 180

test/test_cache.py

@@ -1,6 +1,8 @@
+from unittest import mock
+
 import pytest
 
-from aurweb import cache, db
+from aurweb import cache, config, db
 from aurweb.models.account_type import USER_ID
 from aurweb.models.user import User
 
@@ -10,68 +12,85 @@ def setup(db_test):
     return
 
 
-class StubRedis:
-    """A class which acts as a RedisConnection without using Redis."""
-
-    cache = dict()
-    expires = dict()
-
-    def get(self, key, *args):
-        if "key" not in self.cache:
-            self.cache[key] = None
-        return self.cache[key]
-
-    def set(self, key, *args):
-        self.cache[key] = list(args)[0]
-
-    def expire(self, key, *args):
-        self.expires[key] = list(args)[0]
-
-    async def execute(self, command, key, *args):
-        f = getattr(self, command)
-        return f(key, *args)
-
-
 @pytest.fixture
-def redis():
+def user() -> User:
-    yield StubRedis()
+    with db.begin():
+        user = db.create(
+            User,
+            Username="test",
+            Email="test@example.org",
+            RealName="Test User",
+            Passwd="testPassword",
+            AccountTypeID=USER_ID,
+        )
+    yield user
+
+
+@pytest.fixture(autouse=True)
+def clear_fakeredis_cache():
+    cache._redis.flushall()
 
 
 @pytest.mark.asyncio
-async def test_db_count_cache(redis):
+async def test_db_count_cache(user):
-    db.create(
-        User,
-        Username="user1",
-        Email="user1@example.org",
-        Passwd="testPassword",
-        AccountTypeID=USER_ID,
-    )
-
     query = db.query(User)
 
-    # Now, perform several checks that db_count_cache matches query.count().
-
     # We have no cached value yet.
-    assert await cache.db_count_cache(redis, "key1", query) == query.count()
+    assert cache._redis.get("key1") is None
+
+    # Add to cache
+    assert await cache.db_count_cache("key1", query) == query.count()
 
     # It's cached now.
-    assert await cache.db_count_cache(redis, "key1", query) == query.count()
+    assert cache._redis.get("key1") is not None
+
+    # It does not expire
+    assert cache._redis.ttl("key1") == -1
+
+    # Cache a query with an expire.
+    value = await cache.db_count_cache("key2", query, 100)
+    assert value == query.count()
+
+    assert cache._redis.ttl("key2") == 100
 
 
 @pytest.mark.asyncio
-async def test_db_count_cache_expires(redis):
+async def test_db_query_cache(user):
-    db.create(
-        User,
-        Username="user1",
-        Email="user1@example.org",
-        Passwd="testPassword",
-        AccountTypeID=USER_ID,
-    )
-
     query = db.query(User)
 
-    # Cache a query with an expire.
+    # We have no cached value yet.
-    value = await cache.db_count_cache(redis, "key1", query, 100)
+    assert cache._redis.get("key1") is None
-    assert value == query.count()
 
-    assert redis.expires["key1"] == 100
+    # Add to cache
+    await cache.db_query_cache("key1", query)
+
+    # It's cached now.
+    assert cache._redis.get("key1") is not None
+
+    # Modify our user and make sure we got a cached value
+    user.Username = "changed"
+    cached = await cache.db_query_cache("key1", query)
+    assert cached[0].Username != query.all()[0].Username
+
+    # It does not expire
+    assert cache._redis.ttl("key1") == -1
+
+    # Cache a query with an expire.
+    value = await cache.db_query_cache("key2", query, 100)
+    assert len(value) == query.count()
+    assert value[0].Username == query.all()[0].Username
+
+    assert cache._redis.ttl("key2") == 100
+
+    # Test "max_search_entries" options
+    def mock_max_search_entries(section: str, key: str, fallback: int) -> str:
+        if section == "cache" and key == "max_search_entries":
+            return 1
+        return config.getint(section, key)
+
+    with mock.patch("aurweb.config.getint", side_effect=mock_max_search_entries):
+        # Try to add another entry (we already have 2)
+        await cache.db_query_cache("key3", query)
+
+        # Make sure it was not added because it exceeds our max.
+        assert cache._redis.get("key3") is None

test/test_packages_routes.py

@@ -5,7 +5,7 @@ from unittest import mock
 import pytest
 from fastapi.testclient import TestClient
 
-from aurweb import asgi, config, db, time
+from aurweb import asgi, cache, config, db, time
 from aurweb.filters import datetime_display
 from aurweb.models import License, PackageLicense
 from aurweb.models.account_type import USER_ID, AccountType
@@ -63,6 +63,11 @@ def setup(db_test):
     return
 
 
+@pytest.fixture(autouse=True)
+def clear_fakeredis_cache():
+    cache._redis.flushall()
+
+
 @pytest.fixture
 def client() -> TestClient:
     """Yield a FastAPI TestClient."""
@@ -815,6 +820,8 @@ def test_packages_search_by_keywords(client: TestClient, packages: list[Package]
 
     # And request packages with that keyword, we should get 1 result.
     with client as request:
+        # clear fakeredis cache
+        cache._redis.flushall()
         response = request.get("/packages", params={"SeB": "k", "K": "testKeyword"})
     assert response.status_code == int(HTTPStatus.OK)
 
@@ -870,6 +877,8 @@ def test_packages_search_by_maintainer(
 
     # This time, we should get `package` returned, since it's now an orphan.
     with client as request:
+        # clear fakeredis cache
+        cache._redis.flushall()
         response = request.get("/packages", params={"SeB": "m"})
     assert response.status_code == int(HTTPStatus.OK)
     root = parse_root(response.text)
@@ -902,6 +911,8 @@ def test_packages_search_by_comaintainer(
 
     # Then test that it's returned by our search.
     with client as request:
+        # clear fakeredis cache
+        cache._redis.flushall()
         response = request.get(
             "/packages", params={"SeB": "c", "K": maintainer.Username}
         )

test/test_util.py

@@ -5,7 +5,8 @@ import fastapi
 import pytest
 from fastapi.responses import JSONResponse
 
-from aurweb import filters, util
+from aurweb import db, filters, util
+from aurweb.models.user import User
 from aurweb.testing.requests import Request
 
 
@@ -146,3 +147,26 @@ def assert_multiple_keys(pks):
     assert key1 == k1[1]
     assert pfx2 == k2[0]
     assert key2 == k2[1]
+
+
+def test_hash_query():
+    # No conditions
+    query = db.query(User)
+    assert util.hash_query(query) == "75e76026b7d576536e745ec22892cf8f5d7b5d62"
+
+    # With where clause
+    query = db.query(User).filter(User.Username == "bla")
+    assert util.hash_query(query) == "4dca710f33b1344c27ec6a3c266970f4fa6a8a00"
+
+    # With where clause and sorting
+    query = db.query(User).filter(User.Username == "bla").order_by(User.Username)
+    assert util.hash_query(query) == "ee2c7846fede430776e140f8dfe1d83cd21d2eed"
+
+    # With where clause, sorting and specific columns
+    query = (
+        db.query(User)
+        .filter(User.Username == "bla")
+        .order_by(User.Username)
+        .with_entities(User.Username)
+    )
+    assert util.hash_query(query) == "c1db751be61443d266cf643005eee7a884dac103"