From eaa678eaa4059a666a2c461fddfe7ecb498628e0 Mon Sep 17 00:00:00 2001
From: Alexander Larsson <alexl@redhat.com>
Date: Thu, 15 Oct 2015 15:54:35 +0200
Subject: [PATCH] deltas: Make apply-offline only read the parts once

No need to read() the file for the checksum if we then directly mmap it.
Instead we just mmap it initially and checksum from that.
---
 src/libostree/ostree-repo-static-delta-core.c | 49 +++++++------------
 1 file changed, 19 insertions(+), 30 deletions(-)

diff --git a/src/libostree/ostree-repo-static-delta-core.c b/src/libostree/ostree-repo-static-delta-core.c
index 1a961664..f014b61a 100644
--- a/src/libostree/ostree-repo-static-delta-core.c
+++ b/src/libostree/ostree-repo-static-delta-core.c
@@ -296,9 +296,7 @@ ostree_repo_static_delta_execute_offline (OstreeRepo                    *self,
       g_autoptr(GVariant) header = NULL;
       g_autoptr(GVariant) csum_v = NULL;
       g_autoptr(GVariant) objects = NULL;
-      g_autoptr(GFile) part_path = NULL;
-      g_autoptr(GInputStream) raw_in = NULL;
-      g_autoptr(GInputStream) in = NULL;
+      g_autoptr(GBytes) bytes = NULL;
       g_autofree char *deltapart_path = NULL;
 
       header = g_variant_get_child_value (headers, i);
@@ -330,17 +328,24 @@ ostree_repo_static_delta_execute_offline (OstreeRepo                    *self,
 
       part_data = g_variant_lookup_value (metadata, deltapart_path, G_VARIANT_TYPE("(yay)"));
       if (part_data)
-        in = ot_variant_read (part_data);
+        {
+          bytes = g_variant_get_data_as_bytes (part_data);
+        }
       else
         {
-          part_path = ot_gfile_resolve_path_printf (dir, "%u", i);
-          in = (GInputStream*)g_file_read (part_path, cancellable, error);
+          g_autoptr(GFile) part_path = ot_gfile_resolve_path_printf (dir, "%u", i);
+          GMappedFile *mfile = gs_file_map_noatime (part_path, cancellable, error);
+          if (!mfile)
+            goto out;
+
+          bytes = g_mapped_file_get_bytes (mfile);
+          g_mapped_file_unref (mfile);
         }
-      if (!in)
-        goto out;
 
       if (!skip_validation)
         {
+          g_autoptr(GInputStream) in = g_memory_input_stream_new_from_bytes (bytes);
+
           g_autofree char *expected_checksum = ostree_checksum_from_bytes (csum);
           if (!_ostree_static_delta_part_validate (self, in, i,
                                                    expected_checksum,
@@ -348,28 +353,12 @@ ostree_repo_static_delta_execute_offline (OstreeRepo                    *self,
             goto out;
         }
 
-      {
-        g_autoptr(GBytes) bytes = NULL;
-
-        if (part_data)
-          bytes = g_variant_get_data_as_bytes (part_data);
-        else
-          {
-            GMappedFile *mfile = gs_file_map_noatime (part_path, cancellable, error);
-            if (!mfile)
-              goto out;
-
-            bytes = g_mapped_file_get_bytes (mfile);
-            g_mapped_file_unref (mfile);
-          }
-        
-        if (!_ostree_static_delta_part_execute (self, objects, bytes,
-                                                cancellable, error))
-          {
-            g_prefix_error (error, "executing delta part %i: ", i);
-            goto out;
-          }
-      }
+      if (!_ostree_static_delta_part_execute (self, objects, bytes,
+                                              cancellable, error))
+        {
+          g_prefix_error (error, "executing delta part %i: ", i);
+          goto out;
+        }
     }
 
   ret = TRUE;