resume downloads automatically

HISTORY.rst

@@ -3,6 +3,14 @@
 Release History
 ---------------
 
+4.0.0 (2024-04-12)
+++++++++++++++++++
+
+**Features and Improvements**
+
+- Partially downloaded files will now automatically resume where they left off when retried.
+- Use ``Last-Modified`` header to set all mtimes (this includes files.xml now).
+
 3.7.0 (2024-03-19)
 ++++++++++++++++++
 

internetarchive/__version__.py

@@ -1 +1 @@
-__version__ = '3.7.0'
+__version__ = '4.0.0.dev1'

internetarchive/exceptions.py

@@ -31,7 +31,16 @@ class AuthenticationError(Exception):
 
 class ItemLocateError(Exception):
     def __init__(self, *args, **kwargs):
-        default_message = 'Item cannot be located because it is dark or does not exist.'
+        default_message = "Item cannot be located because it is dark or does not exist."
+        if args or kwargs:
+            super().__init__(*args, **kwargs)
+        else:
+            super().__init__(default_message)
+
+
+class InvalidChecksumError(Exception):
+    def __init__(self, *args, **kwargs):
+        default_message = "File corrupt, checksums do not match."
         if args or kwargs:
             super().__init__(*args, **kwargs)
         else:

internetarchive/files.py

@@ -29,6 +29,7 @@
 import sys
 from contextlib import nullcontext, suppress
 from email.utils import parsedate_to_datetime
+from time import sleep
 from urllib.parse import quote
 
 from requests.exceptions import (
@@ -40,7 +41,7 @@
 )
 from tqdm import tqdm
 
-from internetarchive import auth, iarequest, utils
+from internetarchive import auth, exceptions, iarequest, utils
 
 log = logging.getLogger(__name__)
 
@@ -137,7 +138,8 @@ def __repr__(self):
                 f'size={self.size!r}, '
                 f'format={self.format!r})')
 
-    def download(self, file_path=None, verbose=None, ignore_existing=None,
+    def download(# noqa: max-complexity=38
+                 self, file_path=None, verbose=None, ignore_existing=None,
                  checksum=None, destdir=None, retries=None, ignore_errors=None,
                  fileobj=None, return_responses=None, no_change_timestamp=None,
                  params=None, chunk_size=None, stdout=None, ors=None,
@@ -205,6 +207,9 @@ def download(self, file_path=None, verbose=None, ignore_existing=None,
         no_change_timestamp = no_change_timestamp or False
         params = params or None
         timeout = 12 if not timeout else timeout
+        headers = {}
+        retries_sleep = 3  # TODO: exponential sleep
+        retrying = False  # for retry loop
 
         self.item.session.mount_http_adapter(max_retries=retries)
         file_path = file_path or self.name
@@ -220,93 +225,138 @@ def download(self, file_path=None, verbose=None, ignore_existing=None,
             file_path = os.path.join(destdir, file_path)
 
         parent_dir = os.path.dirname(file_path)
-        try:
-            if parent_dir != '' and return_responses is not True:
-                os.makedirs(parent_dir, exist_ok=True)
-
-            response = self.item.session.get(self.url,
-                                             stream=True,
-                                             timeout=timeout,
-                                             auth=self.auth,
-                                             params=params)
-
-            # Get timestamp from Last-Modified header
-            dt = parsedate_to_datetime(response.headers['Last-Modified'])
-            last_mod_mtime = dt.timestamp()
-
-            response.raise_for_status()
-
-            # Check if we should skip...
-            if not return_responses and os.path.exists(file_path.encode('utf-8')):
-                if ignore_existing:
-                    msg = f'skipping {file_path}, file already exists.'
-                    log.info(msg)
-                    if verbose:
-                        print(f' {msg}', file=sys.stderr)
-                    return
-                elif checksum:
-                    with open(file_path, 'rb') as fp:
-                        md5_sum = utils.get_md5(fp)
-
-                    if md5_sum == self.md5:
-                        msg = f'skipping {file_path}, file already exists based on checksum.'
+
+        # Retry loop
+        while True:
+            try:
+                if parent_dir != '' and return_responses is not True:
+                    os.makedirs(parent_dir, exist_ok=True)
+
+                if not return_responses \
+                        and not ignore_existing \
+                        and self.name != f'{self.identifier}_files.xml' \
+                        and os.path.exists(file_path.encode('utf-8')):
+                    st = os.stat(file_path.encode('utf-8'))
+                    if st.st_size != self.size and not checksum:
+                        headers = {"Range": f"bytes={st.st_size}-{self.size}"}
+
+                response = self.item.session.get(self.url,
+                                                 stream=True,
+                                                 timeout=timeout,
+                                                 auth=self.auth,
+                                                 params=params,
+                                                 headers=headers)
+
+                # Get timestamp from Last-Modified header
+                last_mod_header = response.headers.get('Last-Modified')
+                if last_mod_header:
+                    dt = parsedate_to_datetime(last_mod_header)
+                    last_mod_mtime = dt.timestamp()
+                else:
+                    last_mod_mtime = 0
+
+                response.raise_for_status()
+
+                # Check if we should skip...
+                if not return_responses and os.path.exists(file_path.encode('utf-8')):
+                    if ignore_existing:
+                        msg = f'skipping {file_path}, file already exists.'
                         log.info(msg)
                         if verbose:
                             print(f' {msg}', file=sys.stderr)
                         return
-                elif not fileobj:
-                    st = os.stat(file_path.encode('utf-8'))
-                    if st.st_mtime == last_mod_mtime:
-                        if self.name == f'{self.identifier}_files.xml' \
-                            or (st.st_size == self.size):
-                            msg = (f'skipping {file_path}, file already exists based on '
-                                    'length and date.')
+                    elif checksum:
+                        with open(file_path, 'rb') as fp:
+                            md5_sum = utils.get_md5(fp)
+
+                        if md5_sum == self.md5:
+                            msg = f'skipping {file_path}, file already exists based on checksum.'
                             log.info(msg)
                             if verbose:
                                 print(f' {msg}', file=sys.stderr)
                             return
-
-            elif return_responses:
-                return response
-
-            if verbose:
-                total = int(response.headers.get('content-length', 0)) or None
-                progress_bar = tqdm(desc=f' downloading {self.name}',
-                                    total=total,
-                                    unit='iB',
-                                    unit_scale=True,
-                                    unit_divisor=1024)
-            else:
-                progress_bar = nullcontext()
-
-            if not chunk_size:
-                chunk_size = 1048576
-            if stdout:
-                fileobj = os.fdopen(sys.stdout.fileno(), "wb", closefd=False)
-            if not fileobj:
-                fileobj = open(file_path.encode('utf-8'), 'wb')
-
-            with fileobj, progress_bar as bar:
-                for chunk in response.iter_content(chunk_size=chunk_size):
-                    if chunk:
-                        size = fileobj.write(chunk)
-                        if bar is not None:
-                            bar.update(size)
-                if ors:
-                    fileobj.write(os.environ.get("ORS", "\n").encode("utf-8"))
-        except (RetryError, HTTPError, ConnectTimeout, OSError, ReadTimeout) as exc:
-            msg = f'error downloading file {file_path}, exception raised: {exc}'
-            log.error(msg)
-            try:
-                os.remove(file_path)
-            except OSError:
-                pass
-            if verbose:
-                print(f' {msg}', file=sys.stderr)
-            if ignore_errors:
-                return False
-            else:
-                raise exc
+                    elif not fileobj:
+                        st = os.stat(file_path.encode('utf-8'))
+                        if st.st_mtime == last_mod_mtime:
+                            if self.name == f'{self.identifier}_files.xml' \
+                                or (st.st_size == self.size):
+                                msg = (f'skipping {file_path}, file already exists based on '
+                                        'length and date.')
+                                log.info(msg)
+                                if verbose:
+                                    print(f' {msg}', file=sys.stderr)
+                                return
+
+                elif return_responses:
+                    return response
+
+
+
+                if verbose:
+                    total = int(response.headers.get('content-length', 0)) or None
+                    progress_bar = tqdm(desc=f' downloading {self.name}',
+                                        total=total,
+                                        unit='iB',
+                                        unit_scale=True,
+                                        unit_divisor=1024)
+                else:
+                    progress_bar = nullcontext()
+
+                if not chunk_size:
+                    chunk_size = 1048576
+                if stdout:
+                    fileobj = os.fdopen(sys.stdout.fileno(), 'wb', closefd=False)
+                if not fileobj or retrying:
+                    if 'Range' in headers:
+                        fileobj = open(file_path.encode('utf-8'), 'ab')
+                    else:
+                        fileobj = open(file_path.encode('utf-8'), 'wb')
+
+                with fileobj, progress_bar as bar:
+                    for chunk in response.iter_content(chunk_size=chunk_size):
+                        if chunk:
+                            size = fileobj.write(chunk)
+                            if bar is not None:
+                                bar.update(size)
+                    if ors:
+                        fileobj.write(os.environ.get("ORS", "\n").encode("utf-8"))
+
+                    if 'Range' in headers:
+                        with open(file_path, 'rb') as fh:
+                            local_checksum = utils.get_md5(fh)
+                        try:
+                            assert local_checksum == self.md5
+                        except AssertionError:
+                            msg = (f"\"{file_path}\" corrupt, "
+                                   "checksums do not match. "
+                                   "Remote file may have been modified, "
+                                   "retry download.")
+                            os.remove(file_path.encode('utf-8'))
+                            raise exceptions.InvalidChecksumError(msg)
+                    break
+            except (RetryError, HTTPError, ConnectTimeout, OSError, ReadTimeout,
+                    exceptions.InvalidChecksumError) as exc:
+                if retries > 0:
+                    retrying = True
+                    retries -= 1
+                    msg = ('download failed, sleeping for '
+                           f'{retries_sleep} seconds and retrying. '
+                           f'{retries} retries left.')
+                    log.warning(msg)
+                    sleep(retries_sleep)
+                    continue
+                msg = f'error downloading file {file_path}, exception raised: {exc}'
+                log.error(msg)
+                try:
+                    os.remove(file_path)
+                except OSError:
+                    pass
+                if verbose:
+                    print(f' {msg}', file=sys.stderr)
+                if ignore_errors:
+                    return False
+                else:
+                    raise exc
 
         # Set mtime with timestamp from Last-Modified header
         if not no_change_timestamp:

tests/test_item.py

@@ -11,6 +11,7 @@
 import internetarchive.files
 from internetarchive import get_session
 from internetarchive.api import get_item
+from internetarchive.exceptions import InvalidChecksumError
 from internetarchive.utils import InvalidIdentifierException, json, norm_filepath
 from tests.conftest import (
     NASA_METADATA_PATH,
@@ -151,6 +152,7 @@ def test_download(tmpdir, nasa_item):
                  adding_headers=EXPECTED_LAST_MOD_HEADER)
         nasa_item.download(files='nasa_meta.xml')
         assert len(tmpdir.listdir()) == 1
+    os.remove('nasa/nasa_meta.xml')
     with IaRequestsMock() as rsps:
         rsps.add(responses.GET, DOWNLOAD_URL_RE,
                  body='new test content',
@@ -198,26 +200,12 @@ def test_download_ignore_existing(tmpdir, nasa_item):
             assert fh.read() == 'test content'
 
 
-def test_download_clobber(tmpdir, nasa_item):
-    tmpdir.chdir()
-    with IaRequestsMock() as rsps:
-        rsps.add(responses.GET, DOWNLOAD_URL_RE,
-                 body='test content',
-                 adding_headers=EXPECTED_LAST_MOD_HEADER)
-        nasa_item.download(files='nasa_meta.xml')
-
-        rsps.reset()
-        rsps.add(responses.GET, DOWNLOAD_URL_RE,
-                 body='new test content',
-                 adding_headers=EXPECTED_LAST_MOD_HEADER)
-        nasa_item.download(files='nasa_meta.xml')
-        assert load_file('nasa/nasa_meta.xml') == 'new test content'
-
-
 def test_download_checksum(tmpdir, caplog):
     tmpdir.chdir()
 
     # test overwrite based on checksum.
+    if os.path.exists('nasa/nasa_meta.xml'):
+        os.remove('nasa/nasa_meta.xml')
     with IaRequestsMock() as rsps:
         rsps.add_metadata_mock('nasa')
         rsps.add(responses.GET, DOWNLOAD_URL_RE,
@@ -229,9 +217,10 @@ def test_download_checksum(tmpdir, caplog):
 
         nasa_item = get_item('nasa')
         nasa_item.download(files='nasa_meta.xml')
-        nasa_item.download(files='nasa_meta.xml', checksum=True)
-
-        assert load_file('nasa/nasa_meta.xml') == 'overwrite based on md5'
+        try:
+            nasa_item.download(files='nasa_meta.xml', checksum=True)
+        except InvalidChecksumError as exc:
+            assert "corrupt, checksums do not match." in str(exc)
 
         # test no overwrite based on checksum.
         with caplog.at_level(logging.DEBUG):