Prefer to select unlocked devices in CI

.gitignore

@@ -9,3 +9,4 @@ mace/codegen/opencl_bin/
 mace/codegen/tuning/
 mace/codegen/version/
 build/
+docs/_build/

tools/bazel_adb_run.py

@@ -86,6 +86,11 @@ def main(unused_args):
         target_socs = set(FLAGS.target_socs.split(','))
     target_devices = sh_commands.adb_devices(target_socs=target_socs)
     if FLAGS.target_socs == "random":
+        unlocked_devices = \
+            [d for d in target_devices if not sh_commands.is_device_locked(d)]
+        if len(unlocked_devices) > 0:
+            target_devices = [random.choice(unlocked_devices)]
+        else:
             target_devices = [random.choice(target_devices)]
 
     target = FLAGS.target

tools/sh_commands.py

@@ -20,6 +20,22 @@ def make_output_processor(buff):
     return process_output
 
 
+def device_lock_path(serialno):
+    return "/tmp/device-lock-%s" % serialno
+
+
+def device_lock(serialno, timeout=3600):
+    return filelock.FileLock(device_lock_path(serialno), timeout=timeout)
+
+
+def is_device_locked(serialno):
+    try:
+        with device_lock(serialno, timeout=0.000001):
+            return False
+    except filelock.Timeout:
+        return True
+
+
 ################################
 # adb commands
 ################################
@@ -90,11 +106,10 @@ def adb_run(serialno,
     print(
         "====================================================================="
     )
-    lock_path = "/tmp/device-lock-%s" % serialno
-    print("Try to lock ", lock_path)
-    with filelock.FileLock(lock_path, timeout=3600):
-        print("Run on device: %s, %s, %s" % (serialno,
-                                             props["ro.board.platform"],
+    print("Trying to lock device", serialno)
+    with device_lock(serialno):
+        print("Run on device: %s, %s, %s" %
+              (serialno, props["ro.board.platform"],
                props["ro.product.model"]))
         sh.adb("-s", serialno, "shell", "rm -rf %s" % device_bin_path)
         sh.adb("-s", serialno, "shell", "mkdir -p %s" % device_bin_path)