Move some functions out of 'api/utils/common.py' (#10948)

### What problem does this PR solve?

as title.

### Type of change

- [x] Refactoring

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

common/misc_utils.py

@@ -18,6 +18,11 @@ import base64
 import hashlib
 import uuid
 import requests
+import threading
+import subprocess
+import sys
+import os
+import logging
 
 def get_uuid():
     return uuid.uuid1().hex
@@ -33,4 +38,71 @@ def download_img(url):
 
 
 def hash_str2int(line: str, mod: int = 10 ** 8) -> int:
-    return int(hashlib.sha1(line.encode("utf-8")).hexdigest(), 16) % mod
+    return int(hashlib.sha1(line.encode("utf-8")).hexdigest(), 16) % mod
+
+def convert_bytes(size_in_bytes: int) -> str:
+    """
+    Format size in bytes.
+    """
+    if size_in_bytes == 0:
+        return "0 B"
+
+    units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB']
+    i = 0
+    size = float(size_in_bytes)
+
+    while size >= 1024 and i < len(units) - 1:
+        size /= 1024
+        i += 1
+
+    if i == 0 or size >= 100:
+        return f"{size:.0f} {units[i]}"
+    elif size >= 10:
+        return f"{size:.1f} {units[i]}"
+    else:
+        return f"{size:.2f} {units[i]}"
+
+
+def once(func):
+    """
+    A thread-safe decorator that ensures the decorated function runs exactly once,
+    caching and returning its result for all subsequent calls. This prevents
+    race conditions in multi-thread environments by using a lock to protect
+    the execution state.
+
+    Args:
+        func (callable): The function to be executed only once.
+
+    Returns:
+        callable: A wrapper function that executes `func` on the first call
+                  and returns the cached result thereafter.
+
+    Example:
+        @once
+        def compute_expensive_value():
+            print("Computing...")
+            return 42
+
+        # First call: executes and prints
+        # Subsequent calls: return 42 without executing
+    """
+    executed = False
+    result = None
+    lock = threading.Lock()
+    def wrapper(*args, **kwargs):
+        nonlocal executed, result
+        with lock:
+            if not executed:
+                executed = True
+                result = func(*args, **kwargs)
+        return result
+    return wrapper
+
+@once
+def pip_install_torch():
+    device = os.getenv("DEVICE", "cpu")
+    if device=="cpu":
+        return
+    logging.info("Installing pytorch")
+    pkg_names = ["torch>=2.5.0,<3.0.0"]
+    subprocess.check_call([sys.executable, "-m", "pip", "install", *pkg_names])