samples: Add samples for async download files #1470 (#1471)

chandra-siri · cojenco · web-flow · commit 8f56cc812bfb · 2025-05-05T16:09:37.000Z
* samples: Add samples for async download files #1470 * Add argument description for `async_download_blobs` function. Co-authored-by: cojenco <cathyo@google.com> * Addressed comments from cojenco@ * change download_as_string to bytes * Don't print blob contents after downloading * remove Google Inc , add Google LLC * pass list of file_names as one of the params. * fix lint issues * fix whitespace lints * remove unused variable i --------- Co-authored-by: cojenco <cathyo@google.com>
diff --git a/samples/snippets/snippets_test.py b/samples/snippets/snippets_test.py
@@ -26,6 +26,7 @@
 
 import storage_add_bucket_label
 import storage_async_upload
+import storage_async_download
 import storage_batch_request
 import storage_bucket_delete_default_kms_key
 import storage_change_default_storage_class
@@ -267,6 +268,19 @@ def test_async_upload(bucket, capsys):
     assert f"Uploaded 3 files to bucket {bucket.name}" in out
 
 
+def test_async_download(test_bucket, capsys):
+    object_count = 3
+    source_files = [f"async_sample_blob_{x}" for x in range(object_count)]
+    for source in source_files:
+        blob = test_bucket.blob(source)
+        blob.upload_from_string(source)
+
+    asyncio.run(storage_async_download.async_download_blobs(test_bucket.name, *source_files))
+    out, _ = capsys.readouterr()
+    for x in range(object_count):
+        assert f"Downloaded storage object async_sample_blob_{x}" in out
+
+
 def test_download_byte_range(test_blob):
     with tempfile.NamedTemporaryFile() as dest_file:
         storage_download_byte_range.download_byte_range(
diff --git a/samples/snippets/storage_async_download.py b/samples/snippets/storage_async_download.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python
+
+# Copyright 2025 Google LLC.
+#
+# Licensed under the Apache License, Version 2.0 (the 'License');
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+import argparse
+
+"""Sample that asynchronously downloads multiple files from GCS to application's memory.
+"""
+
+
+# [START storage_async_download]
+# This sample can be run by calling `async.run(async_download_blobs('bucket_name', ['file1', 'file2']))`
+async def async_download_blobs(bucket_name, *file_names):
+    """Downloads a number of files in parallel from the bucket.
+    """
+    # The ID of your GCS bucket.
+    # bucket_name = "your-bucket-name"
+
+    # The list of files names to download, these files should be present in bucket.
+    # file_names = ["myfile1", "myfile2"]
+
+    import asyncio
+    from google.cloud import storage
+
+    storage_client = storage.Client()
+    bucket = storage_client.bucket(bucket_name)
+
+    loop = asyncio.get_running_loop()
+
+    tasks = []
+    for file_name in file_names:
+        blob = bucket.blob(file_name)
+        # The first arg, None, tells it to use the default loops executor
+        tasks.append(loop.run_in_executor(None, blob.download_as_bytes))
+
+    # If the method returns a value (such as download_as_bytes), gather will return the values
+    _ = await asyncio.gather(*tasks)
+    for file_name in file_names:
+        print(f"Downloaded storage object {file_name}")
+
+
+# [END storage_async_download]
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-b', '--bucket_name', type=str, dest='bucket_name', help='provide the name of the GCS bucket')
+    parser.add_argument(
+        '-f', '--file_name',
+        action='append',
+        type=str,
+        dest='file_names',
+        help='Example: -f file1.txt or --file_name my_fav.mp4 . It can be used multiple times.'
+    )
+    args = parser.parse_args()
+
+    asyncio.run(async_download_blobs(args.bucket_name, *args.file_names))
