Parallelize src/test/test into chunks.

First, we introduce a flag to teach src/test/test to split its work
into chunks.  Then we replace our invocation of src/test/test in our
"make check" target with a set of 8 scripts that invoke the first
8th of the tests, the second 8th, and so on.

This change makes our "make -kj4 check" target in our hardened
gitlab build more than twice as fast, since src/test/test was taking
the longest to finish.

Closes 40098.

1 files changed, 42 insertions, 0 deletions

diff --git a/src/test/testing_common.c b/src/test/testing_common.c
index 2c9c4538b9..daa7aa524a 100644
--- a/src/test/testing_common.c
+++ b/src/test/testing_common.c
@@ -278,6 +278,8 @@ main(int c, const char **v)
   control_initialize_event_queue();
   configure_backtrace_handler(get_version());
 
+  unsigned num=1, den=1;
+
   for (i_out = i = 1; i < c; ++i) {
     if (!strcmp(v[i], "--warn")) {
       loglevel = LOG_WARN;
@@ -289,6 +291,19 @@ main(int c, const char **v)
       loglevel = LOG_DEBUG;
     } else if (!strcmp(v[i], "--accel")) {
       accel_crypto = 1;
+    } else if (!strcmp(v[i], "--fraction")) {
+      if (i+1 == c) {
+        printf("--fraction needs an argument.\n");
+        return 1;
+      }
+      const char *fracstr = v[++i];
+      char ch;
+      if (sscanf(fracstr, "%u/%u%c", &num, &den, &ch) != 2) {
+        printf("--fraction expects a fraction as an input.\n");
+      }
+      if (den == 0 || num == 0 || num > den) {
+        printf("--fraction expects a valid fraction as an input.\n");
+      }
     } else {
       v[i_out++] = v[i];
     }
@@ -363,6 +378,33 @@ main(int c, const char **v)
     smartlist_free(skip);
   }
 
+  if (den != 1) {
+    // count the tests. Linear but fast.
+    unsigned n_tests = 0;
+    struct testgroup_t *tg;
+    struct testcase_t *tc;
+    for (tg = testgroups; tg->prefix != NULL; ++tg) {
+      for (tc = tg->cases; tc->name != NULL; ++tc) {
+        ++n_tests;
+      }
+    }
+    // Which tests should we run?  This can give iffy results if den is huge
+    // but it doesn't actually matter in practice.
+    unsigned tests_per_chunk = CEIL_DIV(n_tests, den);
+    unsigned start_at = (num-1) * tests_per_chunk;
+
+    // Skip the tests that are outside of the range.
+    unsigned idx = 0;
+    for (tg = testgroups; tg->prefix != NULL; ++tg) {
+      for (tc = tg->cases; tc->name != NULL; ++tc) {
+        if (idx < start_at || idx >= start_at + tests_per_chunk) {
+          tc->flags |= TT_SKIP;
+        }
+        ++idx;
+      }
+    }
+  }
+
   int have_failed = (tinytest_main(c, v, testgroups) != 0);
 
   free_pregenerated_keys();