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Yuvi9587
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multipart_downloader.py
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232
multipart_downloader.py
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import os
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import time
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import requests
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import hashlib
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import http.client
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import traceback
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import threading
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from concurrent.futures import ThreadPoolExecutor, as_completed
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CHUNK_DOWNLOAD_RETRY_DELAY = 2 # Slightly reduced for faster retries if needed
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MAX_CHUNK_DOWNLOAD_RETRIES = 1 # Further reduced for quicker fallback if a chunk is problematic
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DOWNLOAD_CHUNK_SIZE_ITER = 1024 * 256 # 256KB for iter_content within a chunk download
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def _download_individual_chunk(chunk_url, temp_file_path, start_byte, end_byte, headers,
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part_num, total_parts, progress_data, cancellation_event, skip_event, logger,
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signals=None, api_original_filename=None): # Added signals and api_original_filename
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"""Downloads a single chunk of a file and writes it to the temp file."""
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if cancellation_event and cancellation_event.is_set():
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logger(f" [Chunk {part_num + 1}/{total_parts}] Download cancelled before start.")
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return 0, False # bytes_downloaded, success
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if skip_event and skip_event.is_set():
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logger(f" [Chunk {part_num + 1}/{total_parts}] Skip event triggered before start.")
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return 0, False
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chunk_headers = headers.copy()
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# end_byte can be -1 for 0-byte files, meaning download from start_byte to end of file (which is start_byte itself)
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if end_byte != -1 : # For 0-byte files, end_byte might be -1, Range header should not be set or be 0-0
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chunk_headers['Range'] = f"bytes={start_byte}-{end_byte}"
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elif start_byte == 0 and end_byte == -1: # Specifically for 0-byte files
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# Some servers might not like Range: bytes=0--1.
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# For a 0-byte file, we might not even need a range header, or Range: bytes=0-0
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# Let's try without for 0-byte, or rely on server to handle 0-0 if Content-Length was 0.
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# If Content-Length was 0, the main function might handle it directly.
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# This chunking logic is primarily for files > 0 bytes.
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# For now, if end_byte is -1, it implies a 0-byte file, so we expect 0 bytes.
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pass
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bytes_this_chunk = 0
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last_progress_emit_time_for_chunk = time.time()
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last_speed_calc_time = time.time()
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bytes_at_last_speed_calc = 0
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for attempt in range(MAX_CHUNK_DOWNLOAD_RETRIES + 1):
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if cancellation_event and cancellation_event.is_set():
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logger(f" [Chunk {part_num + 1}/{total_parts}] Cancelled during retry loop.")
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return bytes_this_chunk, False
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if skip_event and skip_event.is_set():
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logger(f" [Chunk {part_num + 1}/{total_parts}] Skip event during retry loop.")
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return bytes_this_chunk, False
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try:
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if attempt > 0:
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logger(f" [Chunk {part_num + 1}/{total_parts}] Retrying download (Attempt {attempt}/{MAX_CHUNK_DOWNLOAD_RETRIES})...")
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time.sleep(CHUNK_DOWNLOAD_RETRY_DELAY * (2 ** (attempt - 1)))
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# Reset speed calculation on retry
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last_speed_calc_time = time.time()
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bytes_at_last_speed_calc = bytes_this_chunk # Current progress of this chunk
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# Enhanced log message for chunk start
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log_msg = f" 🚀 [Chunk {part_num + 1}/{total_parts}] Starting download: bytes {start_byte}-{end_byte if end_byte != -1 else 'EOF'}"
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logger(log_msg)
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print(f"DEBUG_MULTIPART: {log_msg}") # Direct console print for debugging
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response = requests.get(chunk_url, headers=chunk_headers, timeout=(10, 120), stream=True)
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response.raise_for_status()
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# For 0-byte files, if end_byte was -1, we expect 0 content.
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if start_byte == 0 and end_byte == -1 and int(response.headers.get('Content-Length', 0)) == 0:
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logger(f" [Chunk {part_num + 1}/{total_parts}] Confirmed 0-byte file.")
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with progress_data['lock']:
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progress_data['chunks_status'][part_num]['active'] = False
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progress_data['chunks_status'][part_num]['speed_bps'] = 0
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return 0, True
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with open(temp_file_path, 'r+b') as f: # Open in read-write binary
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f.seek(start_byte)
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for data_segment in response.iter_content(chunk_size=DOWNLOAD_CHUNK_SIZE_ITER):
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if cancellation_event and cancellation_event.is_set():
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logger(f" [Chunk {part_num + 1}/{total_parts}] Cancelled during data iteration.")
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return bytes_this_chunk, False
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if skip_event and skip_event.is_set():
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logger(f" [Chunk {part_num + 1}/{total_parts}] Skip event during data iteration.")
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return bytes_this_chunk, False
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if data_segment:
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f.write(data_segment)
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bytes_this_chunk += len(data_segment)
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with progress_data['lock']:
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# Increment both the chunk's downloaded and the overall downloaded
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progress_data['total_downloaded_so_far'] += len(data_segment)
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progress_data['chunks_status'][part_num]['downloaded'] = bytes_this_chunk
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progress_data['chunks_status'][part_num]['active'] = True
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current_time = time.time()
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time_delta_speed = current_time - last_speed_calc_time
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if time_delta_speed > 0.5: # Calculate speed every 0.5 seconds
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bytes_delta = bytes_this_chunk - bytes_at_last_speed_calc
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current_speed_bps = (bytes_delta * 8) / time_delta_speed if time_delta_speed > 0 else 0
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progress_data['chunks_status'][part_num]['speed_bps'] = current_speed_bps
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last_speed_calc_time = current_time
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bytes_at_last_speed_calc = bytes_this_chunk
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# Emit progress more frequently from within the chunk download
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if current_time - last_progress_emit_time_for_chunk > 0.1: # Emit up to 10 times/sec per chunk
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if signals and hasattr(signals, 'file_progress_signal'):
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# Ensure we read the latest total downloaded from progress_data
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# Send a copy of the chunks_status list
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status_list_copy = [dict(s) for s in progress_data['chunks_status']] # Make a deep enough copy
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signals.file_progress_signal.emit(api_original_filename, status_list_copy)
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last_progress_emit_time_for_chunk = current_time
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return bytes_this_chunk, True
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except (requests.exceptions.ConnectionError, requests.exceptions.Timeout, http.client.IncompleteRead) as e:
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logger(f" ❌ [Chunk {part_num + 1}/{total_parts}] Retryable error: {e}")
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if attempt == MAX_CHUNK_DOWNLOAD_RETRIES:
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logger(f" ❌ [Chunk {part_num + 1}/{total_parts}] Failed after {MAX_CHUNK_DOWNLOAD_RETRIES} retries.")
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return bytes_this_chunk, False
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except requests.exceptions.RequestException as e: # Includes 4xx/5xx errors after raise_for_status
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logger(f" ❌ [Chunk {part_num + 1}/{total_parts}] Non-retryable error: {e}")
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return bytes_this_chunk, False
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except Exception as e:
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logger(f" ❌ [Chunk {part_num + 1}/{total_parts}] Unexpected error: {e}\n{traceback.format_exc(limit=1)}")
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return bytes_this_chunk, False
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# Ensure final status is marked as inactive if loop finishes due to retries
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with progress_data['lock']:
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progress_data['chunks_status'][part_num]['active'] = False
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progress_data['chunks_status'][part_num]['speed_bps'] = 0
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return bytes_this_chunk, False # Should be unreachable
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def download_file_in_parts(file_url, save_path, total_size, num_parts, headers,
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api_original_filename, signals, cancellation_event, skip_event, logger):
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"""
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Downloads a file in multiple parts concurrently.
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Returns: (download_successful_flag, downloaded_bytes, calculated_file_hash, temp_file_handle_or_None)
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The temp_file_handle will be an open read-binary file handle to the .part file if successful, otherwise None.
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It is the responsibility of the caller to close this handle and rename/delete the .part file.
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"""
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logger(f"⬇️ Initializing Multi-part Download ({num_parts} parts) for: '{api_original_filename}' (Size: {total_size / (1024*1024):.2f} MB)")
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temp_file_path = save_path + ".part"
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try:
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with open(temp_file_path, 'wb') as f_temp:
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if total_size > 0:
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f_temp.truncate(total_size) # Pre-allocate space
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except IOError as e:
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logger(f" ❌ Error creating/truncating temp file '{temp_file_path}': {e}")
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return False, 0, None, None
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chunk_size_calc = total_size // num_parts
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chunks_ranges = []
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for i in range(num_parts):
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start = i * chunk_size_calc
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end = start + chunk_size_calc - 1 if i < num_parts - 1 else total_size - 1
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if start <= end: # Valid range
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chunks_ranges.append((start, end))
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elif total_size == 0 and i == 0: # Special case for 0-byte file
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chunks_ranges.append((0, -1)) # Indicates 0-byte file, download 0 bytes from offset 0
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chunk_actual_sizes = []
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for start, end in chunks_ranges:
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if end == -1 and start == 0: # 0-byte file
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chunk_actual_sizes.append(0)
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else:
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chunk_actual_sizes.append(end - start + 1)
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if not chunks_ranges and total_size > 0:
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logger(f" ⚠️ No valid chunk ranges for multipart download of '{api_original_filename}'. Aborting multipart.")
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if os.path.exists(temp_file_path): os.remove(temp_file_path)
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return False, 0, None, None
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progress_data = {
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'total_file_size': total_size, # Overall file size for reference
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'total_downloaded_so_far': 0, # New key for overall progress
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'chunks_status': [ # Status for each chunk
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{'id': i, 'downloaded': 0, 'total': chunk_actual_sizes[i] if i < len(chunk_actual_sizes) else 0, 'active': False, 'speed_bps': 0.0}
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for i in range(num_parts)
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],
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'lock': threading.Lock()
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}
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chunk_futures = []
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all_chunks_successful = True
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total_bytes_from_chunks = 0 # Still useful to verify total downloaded against file size
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with ThreadPoolExecutor(max_workers=num_parts, thread_name_prefix=f"MPChunk_{api_original_filename[:10]}_") as chunk_pool:
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for i, (start, end) in enumerate(chunks_ranges):
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if cancellation_event and cancellation_event.is_set(): all_chunks_successful = False; break
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chunk_futures.append(chunk_pool.submit(
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_download_individual_chunk, chunk_url=file_url, temp_file_path=temp_file_path,
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start_byte=start, end_byte=end, headers=headers, part_num=i, total_parts=num_parts,
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progress_data=progress_data, cancellation_event=cancellation_event, skip_event=skip_event, logger=logger,
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signals=signals, api_original_filename=api_original_filename # Pass them here
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))
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for future in as_completed(chunk_futures):
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if cancellation_event and cancellation_event.is_set(): all_chunks_successful = False; break
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bytes_downloaded_this_chunk, success_this_chunk = future.result()
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total_bytes_from_chunks += bytes_downloaded_this_chunk
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if not success_this_chunk:
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all_chunks_successful = False
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# Progress is emitted from within _download_individual_chunk
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if cancellation_event and cancellation_event.is_set():
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logger(f" Multi-part download for '{api_original_filename}' cancelled by main event.")
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all_chunks_successful = False
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# Ensure a final progress update is sent with all chunks marked inactive (unless still active due to error)
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if signals and hasattr(signals, 'file_progress_signal'):
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with progress_data['lock']:
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# Ensure all chunks are marked inactive for the final signal if download didn't fully succeed or was cancelled
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status_list_copy = [dict(s) for s in progress_data['chunks_status']]
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signals.file_progress_signal.emit(api_original_filename, status_list_copy)
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if all_chunks_successful and (total_bytes_from_chunks == total_size or total_size == 0):
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logger(f" ✅ Multi-part download successful for '{api_original_filename}'. Total bytes: {total_bytes_from_chunks}")
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md5_hasher = hashlib.md5()
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with open(temp_file_path, 'rb') as f_hash:
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for buf in iter(lambda: f_hash.read(4096*10), b''): # Read in larger buffers for hashing
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md5_hasher.update(buf)
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calculated_hash = md5_hasher.hexdigest()
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# Return an open file handle for the caller to manage (e.g., for compression)
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# The caller is responsible for closing this handle and renaming/deleting the .part file.
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return True, total_bytes_from_chunks, calculated_hash, open(temp_file_path, 'rb')
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else:
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logger(f" ❌ Multi-part download failed for '{api_original_filename}'. Success: {all_chunks_successful}, Bytes: {total_bytes_from_chunks}/{total_size}. Cleaning up.")
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if os.path.exists(temp_file_path):
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try: os.remove(temp_file_path)
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except OSError as e: logger(f" Failed to remove temp part file '{temp_file_path}': {e}")
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return False, total_bytes_from_chunks, None, None
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