From 0baf56eb55ab99dceae218247057a0e57ea04057 Mon Sep 17 00:00:00 2001
From: Lars-Dominik Braun <lars@6xq.net>
Date: Tue, 21 Nov 2017 14:45:26 +0100
Subject: Graceful page load timeout

Stop scrolling script, wait for remaining resources to load.
---
 crocoite/cli.py         | 35 ++++++++++++++++++++++++++---------
 crocoite/data/scroll.js |  8 ++++++--
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/crocoite/cli.py b/crocoite/cli.py
index aee00e3..86ff0ad 100644
--- a/crocoite/cli.py
+++ b/crocoite/cli.py
@@ -29,7 +29,7 @@ from logging.handlers import BufferingHandler
 from http.server import BaseHTTPRequestHandler
 from io import BytesIO
 import argparse
-import tempfile
+import tempfile, random
 
 from html5lib.treewalkers.base import TreeWalker
 from html5lib.filters.base import Filter
@@ -53,6 +53,11 @@ def packageUrl (path):
     """
     return 'urn:' + __package__ + ':' + path
 
+def randomString (length=None, chars='abcdefghijklmnopqrstuvwxyz'):
+    if length is None:
+        length = random.randint (16, 32)
+    return ''.join (map (lambda x: random.choice (chars), range (length)))
+
 class WARCLogHandler (BufferingHandler):
     """
     Buffered log handler, flushing to warcio
@@ -321,7 +326,7 @@ def main ():
     parser = argparse.ArgumentParser(description='Save website to WARC using Google Chrome.')
     parser.add_argument('--browser', default='http://127.0.0.1:9222', help='DevTools URL')
     parser.add_argument('--timeout', default=10, type=int, help='Maximum time for archival')
-    parser.add_argument('--waitstep', default=2, type=int, help='')
+    parser.add_argument('--idle-timeout', default=2, type=int, help='Maximum idle seconds (i.e. no requests)', dest='idleTimeout')
     parser.add_argument('--onload', default=packageData ('scroll.js'), help='')
     parser.add_argument('--log-buffer', default=1000, type=int, dest='logBuffer')
     parser.add_argument('--keep-tab', action='store_true', default=False, dest='keepTab', help='Keep tab open')
@@ -330,8 +335,12 @@ def main ():
 
     args = parser.parse_args ()
 
+    stopVarname = '__' + __package__ + '_stop__'
+    # avoid sites messing with our scripts by using a random stop variable name
+    newStopVarname = randomString ()
     with open (args.onload, 'r') as fd:
-        onload = fd.read ()
+        onload = 'var {} = false;\n'.format (newStopVarname) + fd.read ().replace (stopVarname, newStopVarname)
+    stopVarname = newStopVarname
 
     # temporary store for requests
     requests = {}
@@ -384,14 +393,22 @@ def main ():
 
     tab.Page.navigate(url=args.url)
 
-    # smaller waitstep might miss some requests issued very late, larger
-    # waitstep may waste time
-    for i in range (0, args.timeout, args.waitstep):
-        tab.wait (args.waitstep)
+    idleTimeout = 0
+    for i in range (0, args.timeout):
+        tab.wait (1)
         if len (requests) == 0:
-            break
+            idleTimeout += 1
+            if idleTimeout > args.idleTimeout:
+                break
+        else:
+            idleTimeout = 0
+
+    # get ready for snapshot: stop loading and scripts, disable events
+    tab.Runtime.evaluate (expression='{} = true; window.scrollTo (0, 0);'.format (stopVarname), returnByValue=True)
+    # if we stopped due to timeout, wait for remaining assets
+    while len (requests) != 0:
+        tab.wait (1)
 
-    # disable events
     tab.Page.stopLoading ()
     tab.Network.disable ()
     tab.Page.disable ()
diff --git a/crocoite/data/scroll.js b/crocoite/data/scroll.js
index cf060fc..d16383c 100644
--- a/crocoite/data/scroll.js
+++ b/crocoite/data/scroll.js
@@ -1,7 +1,11 @@
 (function(){
 function scroll (event) {
-    window.scrollBy (0, window.innerHeight/2);
-    return true;
+	if (__crocoite_stop__) {
+		return false;
+	} else {
+		window.scrollBy (0, window.innerHeight/2);
+		return true;
+	}
 }
 function onload (event) {
     window.setInterval (scroll, 200);
-- 
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