From 62ad973fe48319caaadede5c36370bcd08542fbf Mon Sep 17 00:00:00 2001
From: Maxime Devos <maximedevos@telenet.be>
Date: Thu, 9 Sep 2021 17:42:49 +0200
Subject: [PATCH 03/10] store: Define new add-temp-root-and-valid-path?
 operation.

This will allow speeding up 'local-file-compiler' a little,
see <https://issues.guix.gnu.org/50384>.

* nix/libstore/worker-protocols.hh
  (WorkerOp)[wopAddTempRootAndIsValidPath): New operation.
  (PROTOCOL_VERSION): Bump version.
* nix/nix-daemon/nix-daemon.cc
  (performOp)[wopAddTempRootAndIsValidPath]: Handle new operation.
* guix/store.scm
  (add-temp-root-and-valid-path?): New operation.
  (operation-id)[add-temp-root-and-valid-path?): New operation.
  (%protocol-version): Bump version.
* tests/store.scm
  ("add-temp-root-valid-path? live", "add-temp-root-and-valid-path? false"):
  New tests.
---
 guix/store.scm                  | 11 +++++++++--
 nix/libstore/worker-protocol.hh |  5 +++--
 nix/nix-daemon/nix-daemon.cc    | 12 ++++++++++++
 tests/store.scm                 | 10 ++++++++++
 4 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/guix/store.scm b/guix/store.scm
index 0463b0e8fa..c9f7b905b7 100644
--- a/guix/store.scm
+++ b/guix/store.scm
@@ -124,6 +124,7 @@
             ensure-path
             find-roots
             add-temp-root
+            add-temp-root-and-valid-path?
             add-indirect-root
             add-permanent-root
             remove-permanent-root
@@ -195,7 +196,7 @@
             derivation-log-file
             log-file))
 
-(define %protocol-version #x163)
+(define %protocol-version #x164)
 
 (define %worker-magic-1 #x6e697863)               ; "nixc"
 (define %worker-magic-2 #x6478696f)               ; "dxio"
@@ -249,7 +250,8 @@
   (query-valid-derivers 33)
   (optimize-store 34)
   (verify-store 35)
-  (built-in-builders 80))
+  (built-in-builders 80)
+  (add-temp-root-and-valid-path? 81))
 
 (define-enumerate-type hash-algo
   ;; hash.hh
@@ -1455,6 +1457,11 @@ potential roots that do not point to store items."
 Return #t."
   boolean)
 
+(define-operation (add-temp-root-and-valid-path? (store-path path))
+  "Make PATH a temporary root for the duration of the current session,
+and test if PATH is a valid store path (see 'valid-path?')."
+  boolean)
+
 (define-operation (add-indirect-root (string file-name))
   "Make the symlink FILE-NAME an indirect root for the garbage collector:
 whatever store item FILE-NAME points to will not be collected.  Return #t on
diff --git a/nix/libstore/worker-protocol.hh b/nix/libstore/worker-protocol.hh
index ea67b10a5b..bb99e632cf 100644
--- a/nix/libstore/worker-protocol.hh
+++ b/nix/libstore/worker-protocol.hh
@@ -6,7 +6,7 @@ namespace nix {
 #define WORKER_MAGIC_1 0x6e697863
 #define WORKER_MAGIC_2 0x6478696f
 
-#define PROTOCOL_VERSION 0x163
+#define PROTOCOL_VERSION 0x164
 #define GET_PROTOCOL_MAJOR(x) ((x) & 0xff00)
 #define GET_PROTOCOL_MINOR(x) ((x) & 0x00ff)
 
@@ -44,7 +44,8 @@ typedef enum {
     wopQueryValidDerivers = 33,
     wopOptimiseStore = 34,
     wopVerifyStore = 35,
-    wopBuiltinBuilders = 80
+    wopBuiltinBuilders = 80,
+    wopAddTempRootAndIsValidPath = 81
 } WorkerOp;
 
 
diff --git a/nix/nix-daemon/nix-daemon.cc b/nix/nix-daemon/nix-daemon.cc
index 497de11a04..b73bb15a64 100644
--- a/nix/nix-daemon/nix-daemon.cc
+++ b/nix/nix-daemon/nix-daemon.cc
@@ -306,6 +306,18 @@ static void performOp(bool trusted, unsigned int clientVersion,
         break;
     }
 
+    case wopAddTempRootAndIsValidPath: {
+      /* This is a combination of AddTempRoot and IsValidPath, to reduce
+         the numer of RPC calls made by ‘local-file-compiler’ in (guix gexp). */
+        Path path = readStorePath(from);
+        startWork();
+        store->addTempRoot(path);
+        bool result = store->isValidPath(path);
+        stopWork();
+        writeInt(result, to);
+        break;
+    }
+
     case wopQueryValidPaths: {
         PathSet paths = readStorePaths<PathSet>(from);
         startWork();
diff --git a/tests/store.scm b/tests/store.scm
index 3266fa7a82..d724ff18b2 100644
--- a/tests/store.scm
+++ b/tests/store.scm
@@ -1,5 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -138,10 +139,19 @@
   (let ((p (add-text-to-store %store "hello" "hello, world")))
     (valid-path? %store p)))
 
+(test-assert "add-temp-root-valid-path? live"
+  (let ((p (add-text-to-store %store "hello" "hello, world")))
+    (add-temp-root-and-valid-path? %store p)))
+
 (test-assert "valid-path? false"
   (not (valid-path? %store
                     (string-append (%store-prefix) "/"
                                    (make-string 32 #\e) "-foobar"))))
+(test-assert "add-temp-root-and-valid-path? false"
+  (not (add-temp-root-and-valid-path?
+         %store
+         (string-append (%store-prefix) "/"
+                                        (make-string 32 #\e) "-foobar"))))
 
 (test-equal "with-store, multiple values"        ;<https://bugs.gnu.org/42912>
   '(1 2 3)
-- 
2.33.0