[PATCH 24/26] Detect false sharing of recipes

[Jan Kiszka <jan.kiszka@siemens.com>]

From: Jan Kiszka <jan.kiszka@siemens.com>

When a task is run more than once per build, this indicates a bug,
usually (though not only) related to incorrect multiconfig use. Such
bugs are hard to find in practice, so they could benefit from some
tooling.

This adds a very simple but effective check for such re-run scenarios
by putting a "once.<taskname>" stamp file into each workdir during a
build. If such a file already exists, an error is thrown. The workdirs
are purged after the parsing phase on the beginning of each build so
that no false positives are raised.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 meta/classes/isar-events.bbclass | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/meta/classes/isar-events.bbclass b/meta/classes/isar-events.bbclass
index 62eb25d..1335356 100644
--- a/meta/classes/isar-events.bbclass
+++ b/meta/classes/isar-events.bbclass
@@ -4,6 +4,28 @@
 # Copyright (C) 2015-2017 ilbers GmbH
 # Copyright (c) Siemens AG, 2018
 
+addhandler parse_completed
+
+python parse_completed() {
+    bb.utils.remove(d.getVar('TMPDIR') + "/work/*/*/*/temp/once.*")
+}
+parse_completed[eventmask] = "bb.event.ParseCompleted"
+
+addhandler task_started
+
+python task_started() {
+    task = d.getVar('BB_RUNTASK')
+    try:
+        f = open("%s/once.%s" % (d.getVar('T'), task), "x")
+        f.close()
+    except FileExistsError:
+        bb.error("Detect multiple executions of %s in %s" %
+                 (task, d.getVar('WORKDIR')))
+        bb.error("Rerun a clean build with empty STAMPCLEAN " \
+                 "and compare the sigdata files")
+}
+task_started[eventmask] = "bb.build.TaskStarted"
+
 addhandler build_completed
 
 python build_completed() {
-- 
2.16.4