perf(download): use single http session

To resolve packages, we issue a lot of tiny requests to the snapshot
mirror. To speed this up, we now use a session to pool the http
connections and only resolve DNS once. We further re-use the same
session when downloading as this will help us to track rate limits in
the future.

Signed-off-by: Felix Moessbauer <[email protected]>

Author: fmoessbauer

src/debsbom/cli.py

@@ -13,6 +13,8 @@
 from urllib.parse import urlparse
 from pathlib import Path
 
+import requests
+
 from debsbom.download import Compression, SourceArchiveMerger
 
 from .dpkg import package
@@ -158,8 +160,9 @@ def run(args):
         outdir.mkdir(exist_ok=True)
         cache = PersistentResolverCache(outdir / ".cache")
         resolver = PackageResolver.create(Path(args.bomfile))
-        sdl = sdlclient.SnapshotDataLake()
-        downloader = PackageDownloader(args.outdir)
+        rs = requests.Session()
+        sdl = sdlclient.SnapshotDataLake(session=rs)
+        downloader = PackageDownloader(args.outdir, session=rs)
 
         pkgs = []
         local_pkgs = []

src/debsbom/download/download.py

@@ -7,11 +7,13 @@
 from functools import reduce
 import hashlib
 import json
+import shutil
 import sys
 from typing import Generator, Tuple, Type
 from pathlib import Path
 from urllib.request import urlretrieve
 from packageurl import PackageURL
+import requests
 
 from ..dpkg import package
 from ..snapshot import client as sdlclient
@@ -152,10 +154,13 @@ def create(filename: Path) -> Type["PackageResolver"]:
 
 
 class PackageDownloader:
-    def __init__(self, outdir: Path | str = "downloads"):
+    def __init__(
+        self, outdir: Path | str = "downloads", session: requests.Session = requests.Session()
+    ):
         self.dldir = Path(outdir)
         self.dldir.mkdir(exist_ok=True)
         self.to_download: list["sdlclient.RemoteFile"] = []
+        self.rs = session
 
     def register(self, files: list["sdlclient.RemoteFile"]):
         self.to_download.extend(list(files))
@@ -182,5 +187,8 @@ def download(self, progress_cb=None):
                 else:
                     print(f"Checksum mismatch on {f.filename}. Download again.", file=sys.stderr)
             fdst = target.with_suffix(target.suffix + ".tmp")
-            urlretrieve(f.downloadurl, fdst)
+            with self.rs.get(f.downloadurl, stream=True) as r:
+                r.raise_for_status()
+                with open(fdst, "wb") as f:
+                    shutil.copyfileobj(r.raw, f)
             fdst.rename(target)

src/debsbom/snapshot/client.py

@@ -33,7 +33,7 @@ def __init__(self, sdl, name: str):
 
     def versions(self):
         try:
-            r = requests.get(self.sdl.url + f"/mr/package/{self.name}/")
+            r = self.sdl.rs.get(self.sdl.url + f"/mr/package/{self.name}/")
         except RequestException as e:
             raise SnapshotDataLakeError(e)
         for v in r.json().get("result", []):
@@ -55,7 +55,7 @@ def srcfiles(self) -> Generator["RemoteFile", None, None]:
         All files associated with the source package
         """
         try:
-            r = requests.get(
+            r = self.sdl.rs.get(
                 self.sdl.url + f"/mr/package/{self.name}/{self.version}" "/srcfiles?fileinfo=1"
             )
             if r.status_code == 404:
@@ -78,7 +78,7 @@ def binpackages(self) -> Generator["BinaryPackage", None, None]:
         All binary packages created from this source package
         """
         try:
-            r = requests.get(
+            r = self.sdl.rs.get(
                 self.sdl.url + f"/mr/package/{self.name}/{self.version}" "/binpackages"
             )
             data = r.json()
@@ -121,7 +121,7 @@ def files(self, arch: str = None) -> Generator["RemoteFile", None, None]:
             # resolve via binary only
             api = self.sdl.url + f"/mr/binary/{self.binname}/{self.binversion}/binfiles?fileinfo=1"
         try:
-            r = requests.get(api)
+            r = self.sdl.rs.get(api)
             if r.status_code == 404:
                 raise NotFoundOnSnapshotError()
             data = r.json()
@@ -170,12 +170,16 @@ class SnapshotDataLake:
     Snapshot instance to query against
     """
 
-    def __init__(self, url="https://snapshot.debian.org"):
+    def __init__(
+        self, url="https://snapshot.debian.org", session: requests.Session = requests.Session()
+    ):
         self.url = url
+        # reuse the same connection for all requests
+        self.rs = session
 
     def packages(self) -> Generator[Package, None, None]:
         try:
-            r = requests.get(self.url + "/mr/package/")
+            r = self.rs.get(self.url + "/mr/package/")
             data = r.json()
         except RequestException as e:
             raise SnapshotDataLakeError(e)
@@ -184,7 +188,7 @@ def packages(self) -> Generator[Package, None, None]:
 
     def fileinfo(self, hash):
         try:
-            r = requests.get(self.url + f"/mr/file/{hash}/info")
+            r = self.rs.get(self.url + f"/mr/file/{hash}/info")
             data = r.json()
         except RequestException as e:
             raise SnapshotDataLakeError(e)