[Libguestfs] [PATCH] tests/c-api: cache available features

[Pino Toscano]

Build a list of all the features used in action tests, and lazily read
them as needed.  This reduces the number of guestfs_feature_available
calls for a full run from 117 to 18.
---
 generator/tests_c_api.ml | 77 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 73 insertions(+), 4 deletions(-)

diff --git a/generator/tests_c_api.ml b/generator/tests_c_api.ml
index 6be753f..8c4e5ef 100644
--- a/generator/tests_c_api.ml
+++ b/generator/tests_c_api.ml
@@ -28,6 +28,8 @@ open Optgroups
 open Actions
 open Structs
 
+module StringSet = Set.Make (String)
+
 (* Generate the C API tests. *)
 let rec generate_c_api_tests () =
   generate_header CStyle GPLv2plus;
@@ -41,6 +43,7 @@ let rec generate_c_api_tests () =
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <stdbool.h>
 
 #include \"guestfs.h\"
 #include \"guestfs-internal-frontend.h\"
@@ -53,6 +56,74 @@ let rec generate_c_api_tests () =
 #error Missing GUESTFS_ISO_SYSTEM_ID for the current OS
 #endif
 
+struct feature {
+  const char *name;
+  bool read;
+  bool available;
+};
+
+";
+
+  (* Get a list of all the features. *)
+  let features =
+    List.fold_left (
+      fun acc { optional = optional; tests = tests } ->
+        let acc =
+          match optional with
+          | Some group -> StringSet.add group acc
+          | None -> acc in
+        List.fold_left (
+          fun acc test ->
+            match test with
+            | (_, IfAvailable group, _, _) -> StringSet.add group acc
+            | (_, (Always|IfNotCrossAppliance|Disabled), _, _) -> acc
+        ) acc tests
+    ) StringSet.empty all_functions in
+  let features = List.sort compare (StringSet.elements features) in
+  let nr_features = List.length features in
+  pr "size_t nr_features = %d;\n" nr_features;
+  pr "\n";
+  pr "struct feature features[%d] = {\n" nr_features;
+  List.iter (
+    fun feature ->
+      pr "  { .name = \"%s\", .read = false, .available = false },\n"
+        feature
+  ) features;
+  pr "};\n";
+  pr "\n";
+
+  pr "\
+static bool
+is_feature_available (guestfs_h *g, const char *feature)
+{
+  size_t i;
+
+  for (i = 0; i < nr_features; ++i) {
+    struct feature *f = &features[i];
+
+    if (STRNEQ (f->name, feature))
+      continue;
+
+    if (!f->read) {
+      const char *array[] = { f->name, NULL };
+      int res = guestfs_feature_available (g, (char **) array);
+      if (res < 0) {
+        fprintf (stderr,
+                 \"call to guestfs_feature_available(%%s) failed: %%d, %%s\\n\",
+                 f->name, guestfs_last_errno (g), guestfs_last_error (g));
+        exit (EXIT_FAILURE);
+      }
+
+      f->available = res > 0;
+      f->read = true;
+    }
+
+    return f->available;
+  }
+
+  return false;
+}
+
 ";
 
   (* Generate a list of commands which are not tested anywhere. *)
@@ -140,12 +211,10 @@ static int
    * support is available in the daemon.
    *)
   let group_test group =
-    let sym = gensym "features" in
-    pr "  const char *%s[] = { \"%s\", NULL };\n" sym group;
-    pr "  if (!guestfs_feature_available (g, (char **) %s)) {\n" sym;
+    pr "  if (!is_feature_available (g, \"%s\")) {\n" group;
     pr "    skipped (\"%s\", \"group %%s not available in daemon\",\n"
       test_name;
-    pr "             %s[0]);\n" sym;
+    pr "             \"%s\");\n" group;
     pr "    return 0;\n";
     pr "  }\n";
     pr "\n"
-- 
2.1.0