nodemap: add a new mode value, "strict"

When "strict" is set, operation will refuse to use the slow path and abort if
they would. This is useful for testing, benchmarking and server operation.

Differential Revision: https://phab.mercurial-scm.org/D8415

mercurial/revlogutils/nodemap.py

@@ -148,6 +148,8 b' def _persist_nodemap(tr, revlog, pending'
         msg = _(b"persistent nodemap in strict mode without efficient method")
         if mode == b'warn':
             tr._report(b"%s\n" % msg)
+        elif mode == b'strict':
+            raise error.Abort(msg)
 
     data = None
     # first attemp an incremental update of the data

tests/test-persistent-nodemap.t

@@ -96,6 +96,17 b' add a new commit'
   5001 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ echo foo > foo
   $ hg add foo
+
+#if no-pure no-rust
+
+  $ hg ci -m 'foo' --config "experimental.exp-persistent-nodemap.mode=strict"
+  transaction abort!
+  rollback completed
+  abort: persistent nodemap in strict mode without efficient method
+  [255]
+
+#endif
+
   $ hg ci -m 'foo'
 
 #if no-pure no-rust