[bug#47174] [PATCH 2/2] substitute: Handle closing connections to substitute servers.

[Christopher Baines]

When reusing a HTTP connection to fetch multiple nars, and the remote server
signals that the connection should be closed.

* guix/scripts/substitute.scm (process-substitution): Close connections to
substitute servers when a Connection: close header is specified in the
response.
---
 guix/scripts/substitute.scm | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/guix/scripts/substitute.scm b/guix/scripts/substitute.scm
index cb79ea6927..deb6fbdaa2 100755
--- a/guix/scripts/substitute.scm
+++ b/guix/scripts/substitute.scm
@@ -406,7 +406,9 @@ the current output port."
     (case (uri-scheme uri)
       ((file)
        (let ((port (open-file (uri-path uri) "r0b")))
-         (values port (stat:size (stat port)))))
+         (values port
+                 (stat:size (stat port))
+                 (const #t))))          ; no cleanup to do
       ((http https)
        (guard (c ((http-get-error? c)
                   (leave (G_ "download from '~a' failed: ~a, ~s~%")
@@ -434,7 +436,12 @@ the current output port."
                              #:buffered? #f
                              #:verify-certificate? #f)))
                 (values raw
-                        (response-content-length response))))))))
+                        (response-content-length response)
+                        (match (assq 'connection (response-headers response))
+                          (('connection 'close)
+                           (lambda ()
+                             (close-port (response-port response))))
+                          (_ (const #t))))))))))
       (else
        (leave (G_ "unsupported substitute URI scheme: ~a~%")
               (uri->string uri)))))
@@ -449,7 +456,7 @@ the current output port."
       (format (current-error-port)
               (G_ "Downloading ~a...~%") (uri->string uri)))
 
-    (let*-values (((raw download-size)
+    (let*-values (((raw download-size post-fetch-cleanup)
                    ;; 'guix publish' without '--cache' doesn't specify a
                    ;; Content-Length, so DOWNLOAD-SIZE is #f in this case.
                    (fetch uri))
@@ -493,6 +500,10 @@ the current output port."
       ;; Wait for the reporter to finish.
       (every (compose zero? cdr waitpid) pids)
 
+      ;; Do post-fetch cleanup, maybe closing the HTTP connection if HTTP is
+      ;; being used, and the connection should be closed
+      (post-fetch-cleanup)
+
       ;; Skip a line after what 'progress-reporter/file' printed, and another
       ;; one to visually separate substitutions.
       (display "\n\n" (current-error-port))
-- 
2.30.1