[gimp-web/wip/Jehan/fix-ci] tools: waits a few secs between download loops to prevent IP banning.

[Jehan <jehanp src gnome org>]

commit 9f7bfbcbe2410d691ec8fc07fa4a9c6d3f0a1736
Author: Jehan <jehan girinstud io>
Date:   Mon May 2 16:41:46 2022 +0200

    tools: waits a few secs between download loops to prevent IP banning.
    
    I am not sure at all if this is what we are experiencing (seemingly
    randomly) on some servers, but I wonder if it might be. Basically we try
    to load the tarball, the Windows installer and the macOS DMG in threads,
    so nearly at the same time (if there are enough slots in the thread
    pool). So why do some server seem to take forever? Could it be a
    fail2ban-like service which bans us temporarily when several files are
    requested in a too-short interval?

 tools/downloads/gimp-check-mirrors.py | 11 +++++++++++
 1 file changed, 11 insertions(+)
---
diff --git a/tools/downloads/gimp-check-mirrors.py b/tools/downloads/gimp-check-mirrors.py
index 1559536c..8c3766a2 100755
--- a/tools/downloads/gimp-check-mirrors.py
+++ b/tools/downloads/gimp-check-mirrors.py
@@ -8,6 +8,7 @@ import hashlib
 import re
 import requests
 import sys
+import time
 
 # argparse for mirrorsfile and uri
 parser = argparse.ArgumentParser(description='Check if GIMP download mirrors have a file from 
download.gimp.org.')
@@ -168,6 +169,7 @@ if args.verify_checksum:
 # which is fine by us.
 with concurrent.futures.ThreadPoolExecutor(max_workers=None) as executor:
   test_results = {}
+  first = True
   for local_uri in local_uris:
     test_results[local_uri] = []
 
@@ -175,6 +177,15 @@ with concurrent.futures.ThreadPoolExecutor(max_workers=None) as executor:
     if args.verify_checksum:
       origin_checksum = origin_checksums[local_uri]
 
+    # Some downloads seem to block forever. I wonder if maybe there is a
+    # problem of trying to download immediately several files on a same
+    # mirror and from the same IP. Maybe there is some fail2ban or other
+    # similar service which temporarily bans the test IP?
+    # Let's try to sleep on it a bit and see if it improves things.
+    if not first:
+      time.sleep(5)
+    first = False
+
     with fileinput.input(files=(args.mirrorsfile), mode='r') as f:
       for line in f:
         if args.verify_checksum and line.strip() == 'https://download.gimp.org/pub/gimp/':