bintree: Introduce PORTAGE_BINHOST_TTL setting

Closes: https://bugs.gentoo.org/958401
Closes: #1444
Signed-off-by: Florian Schmaus <[email protected]>
Signed-off-by: Mike Gilbert <[email protected]>

Author: Flowdalic

lib/portage/dbapi/bintree.py

@@ -2177,6 +2177,11 @@ def _update_pkgindex_header(self, header):
             header["URI"] = base_uri
         else:
             header.pop("URI", None)
+        ttl = self.settings.get("PORTAGE_BINHOST_TTL")
+        if ttl:
+            header["TTL"] = ttl
+        else:
+            header.pop("TTL", None)
         for k in (
             list(self._pkgindex_header_keys)
             + self.settings.get("USE_EXPAND_IMPLICIT", "").split()

man/make.conf.5

@@ -1040,6 +1040,14 @@ use the URI header field as a base URI for fetching binary packages. If the URI
 header field is not defined then the client will use its ${PORTAGE_BINHOST}
 setting as the base URI.
 .TP
+\fBPORTAGE_BINHOST_TTL\fR = \
+\fI"3600"\fR
+If this is set, its value will be used to define the TTL header in package
+index.  The TTL header indicates to portage the duration in seconds after
+which the local package index should be considered potentially outdated.  It is
+recommended to set this value to the minimal duration between binary package
+builds to avoid unnecessary network requests on the package index.
+.TP
 .B PORTAGE_BINPKG_FORMAT
 This variable sets default format used for binary packages. Possible values
 are tar and rpm or both. It is very uncommon to set this and is likely