scheduler: resolve git references into revisions on submission (#2296)

Signed-off-by: Charles Baynham <c.baynham@imperial.ac.uk>

RELEASE_NOTES.rst

@@ -45,6 +45,7 @@ Highlights:
 * Full Python 3.10 support.
 * MSYS2 packaging for Windows, which replaces Conda. Conda packages are still available to
   support legacy installations, but may be removed in a future release.
+* Experiments can now be submitted with revisions set to a branch / tag name instead of only git hashes.
 
 Breaking changes:
 

artiq/dashboard/experiments.py

@@ -349,9 +349,10 @@ class _ExperimentDock(QtWidgets.QMdiSubWindow):
             repo_rev = QtWidgets.QLineEdit()
             repo_rev.setPlaceholderText("current")
             repo_rev.setClearButtonEnabled(True)
-            repo_rev_label = QtWidgets.QLabel("Revision:")
+            repo_rev_label = QtWidgets.QLabel("Rev / ref:")
             repo_rev_label.setToolTip("Experiment repository revision "
-                                      "(commit ID) to use")
+                                      "(commit ID) or reference (branch "
+                                      "or tag) to use")
             self.layout.addWidget(repo_rev_label, 3, 2)
             self.layout.addWidget(repo_rev, 3, 3)
 
@@ -739,7 +740,12 @@ class ExperimentManager:
         del self.open_experiments[expurl]
 
     async def _submit_task(self, expurl, *args):
+        try:
             rid = await self.schedule_ctl.submit(*args)
+        except KeyError:
+            expid = args[1]
+            logger.error("Submission failed - revision \"%s\" was not found", expid["repo_rev"])
+        else:
             logger.info("Submitted '%s', RID is %d", expurl, rid)
 
     def submit(self, expurl):

artiq/master/experiments.py

@@ -111,7 +111,7 @@ class ExperimentDB:
         try:
             if new_cur_rev is None:
                 new_cur_rev = self.repo_backend.get_head_rev()
-            wd, _ = self.repo_backend.request_rev(new_cur_rev)
+            wd, _, _ = self.repo_backend.request_rev(new_cur_rev)
             self.repo_backend.release_rev(self.cur_rev)
             self.cur_rev = new_cur_rev
             self.status["cur_rev"] = new_cur_rev
@@ -132,7 +132,7 @@ class ExperimentDB:
         if use_repository:
             if revision is None:
                 revision = self.cur_rev
-            wd, _ = self.repo_backend.request_rev(revision)
+            wd, _, revision = self.repo_backend.request_rev(revision)
             filename = os.path.join(wd, filename)
         worker = Worker(self.worker_handlers)
         try:
@@ -169,7 +169,7 @@ class FilesystemBackend:
         return "N/A"
 
     def request_rev(self, rev):
-        return self.root, None
+        return self.root, None, "N/A"
 
     def release_rev(self, rev):
         pass
@@ -200,14 +200,26 @@ class GitBackend:
     def get_head_rev(self):
         return str(self.git.head.target)
 
+    def _get_pinned_rev(self, rev):
+        """
+        Resolve a git reference (e.g. "HEAD", "master", "abcdef123456...") into
+        a git hash
+        """
+        commit, _ = self.git.resolve_refish(rev)
+
+        logger.debug('Resolved git ref "%s" into "%s"', rev, commit.hex)
+
+        return commit.hex
+
     def request_rev(self, rev):
+        rev = self._get_pinned_rev(rev)
         if rev in self.checkouts:
             co = self.checkouts[rev]
             co.ref_count += 1
         else:
             co = _GitCheckout(self.git, rev)
             self.checkouts[rev] = co
-        return co.path, co.message
+        return co.path, co.message, rev
 
     def release_rev(self, rev):
         co = self.checkouts[rev]

artiq/master/scheduler.py

@@ -132,15 +132,23 @@ class RunPool:
             writer.writerow([rid, start_time, expid["file"]])
 
     def submit(self, expid, priority, due_date, flush, pipeline_name):
+        """
+        Submits an experiment to be run by this pool
+
+        If expid has the attribute `repo_rev`, treat it as a git revision or
+        reference and resolve into a unique git hash before submission
+        """
         # mutates expid to insert head repository revision if None and
         # replaces relative path with the absolute one.
         # called through scheduler.
         rid = self.ridc.get()
         if "repo_rev" in expid:
-            if expid["repo_rev"] is None:
-                expid["repo_rev"] = self.experiment_db.cur_rev
-            wd, repo_msg = self.experiment_db.repo_backend.request_rev(
-                expid["repo_rev"])
+            repo_rev_or_ref = expid["repo_rev"] or self.experiment_db.cur_rev
+            wd, repo_msg, repo_rev = self.experiment_db.repo_backend.request_rev(repo_rev_or_ref)
+
+            # Mutate expid's repo_rev to that returned from request_rev, in case
+            # a branch was passed instead of a hash
+            expid["repo_rev"] = repo_rev
         else:
             if "file" in expid:
                 expid["file"] = os.path.abspath(expid["file"])