Addresses #523

Reordered escalation.
First escalate writes, and only if that succeeds, we escalate the reads.
Now, if we fail during the reads we are still consistent, whereas before
we would need to panic.

git-svn-id: file:///svn/tokudb@2876 c7de825b-a66e-492c-adef-691d508d4ae1

src/lock_tree/locktree.c

@@ -1125,10 +1125,10 @@ static int toku__do_escalation(toku_lock_tree* tree, BOOL* locks_available) {
         r = toku__border_escalation_trivial(tree, &border_range, &trivial);
         if (r!=0)     { goto cleanup; }
         if (!trivial) { continue; }
-        r = toku__escalate_reads_from_border_range(tree, &border_range);
-        if (r!=0)     { r = toku__lt_panic(tree, r); goto cleanup; }
         r = toku__escalate_writes_from_border_range(tree, &border_range);
         if (r!=0)     { r = toku__lt_panic(tree, r); goto cleanup; }
+        r = toku__escalate_reads_from_border_range(tree, &border_range);
+        if (r!=0)     { r = toku__lt_panic(tree, r); goto cleanup; }
     }
     r = 0;
     *locks_available = toku__lt_range_test_incr(tree, 0);