From e24e987c29b21c310ffbc1b65ce0038fecb32cfa Mon Sep 17 00:00:00 2001
From: Magnus Hagander <magnus@hagander.net>
Date: Fri, 20 Nov 2020 16:44:44 +0100
Subject: [PATCH] Only flag docs as loaded when they've actually changed

We already avoided the actual updates (by filtering the UPDATE
statement), but since we set the load date we'd trigger a change to
every page and kick it ouf of the caches even when not chagned, which is
wasteful. So instead only do that if something has changed. When it has,
we still reset that whole version of the docs since we want the load
date to be consistent across them.
---
 tools/docs/docload.py | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/tools/docs/docload.py b/tools/docs/docload.py
index 362da79b..49e323a9 100755
--- a/tools/docs/docload.py
+++ b/tools/docs/docload.py
@@ -193,37 +193,43 @@ if curs.rowcount != pagecount:
     print("Loaded invalid number of rows! {} rows for {} pages!".format(curs.rowcount, pagecount))
     sys.exit(1)
 
+numchanges = 0
+
 # If the previous step succeeded, delete all the documentation for the specified version
 # and insert into / updatethe doc table the content that was loaded into the temporary table
 curs.execute("DELETE FROM docs WHERE version=%(version)s AND NOT EXISTS (SELECT 1 FROM docsload WHERE docsload.file=docs.file)", {
     'version': ver,
 })
+numchanges += curs.rowcount
 if not quiet:
     print("Deleted {} orphaned doc pages".format(curs.rowcount))
 
 curs.execute("INSERT INTO docs (file, version, title, content) SELECT file, version, title, content FROM docsload WHERE NOT EXISTS (SELECT 1 FROM docs WHERE docs.file=docsload.file AND docs.version=%(version)s)", {
     'version': ver,
 })
+numchanges += curs.rowcount
 if not quiet:
     print("Inserted {} new doc pages.".format(curs.rowcount))
 
 curs.execute("UPDATE docs SET title=l.title, content=l.content FROM docsload l WHERE docs.version=%(version)s AND docs.file=l.file AND (docs.title != l.title OR docs.content != l.content)", {
     'version': ver,
 })
+numchanges += curs.rowcount
 if not quiet:
     print("Updated {} changed doc pages.".format(curs.rowcount))
 
-# Update the docs loaded timestamp
-curs.execute("UPDATE core_version SET docsloaded=CURRENT_TIMESTAMP WHERE tree=%(v)s", {'v': ver})
+if numchanges > 0:
+    # Update the docs loaded timestamp
+    curs.execute("UPDATE core_version SET docsloaded=CURRENT_TIMESTAMP WHERE tree=%(v)s", {'v': ver})
 
-# Issue varnish purge for all docs of this version
-if ver == "0":
-    # Special handling of developer docs...
-    ver = "devel"
+    # Issue varnish purge for all docs of this version
+    if ver == "0":
+        # Special handling of developer docs...
+        ver = "devel"
 
-curs.execute("SELECT varnish_purge('^/docs/' || %(v)s || '/')", {'v': ver})
-if iscurrent:
-    curs.execute("SELECT varnish_purge('^/docs/current/')")
+    curs.execute("SELECT varnish_purge('^/docs/' || %(v)s || '/')", {'v': ver})
+    if iscurrent:
+        curs.execute("SELECT varnish_purge('^/docs/current/')")
 
 # ensure the changes are committed, and close the connection
 connection.commit()