Script execution

2019-02-26 14:45:38 +01:00
parent ba369124ce
commit 2fd6cf3b5d
1 changed files with 51 additions and 0 deletions
@@ -53,6 +53,57 @@ class ImageMatrix(ReadonlyRegisterBase, ReadonlyRegisterMatrix, Readable.Integer
   
        

+def is_locked(filepath):
+    """Checks if a file is locked by opening it in append mode.
+    If no exception thrown, then the file is not locked.
+    """
+    locked = None
+    file_object = None
+    filepath = os.path.abspath(filepath)
+    if os.path.exists(filepath):        
+        try:
+            print "Trying to open %s." % filepath
+            buffer_size = 8
+            # Opening file in append mode and read the first 8 characters.
+            file_object = open(filepath, 'a', buffer_size)
+            if file_object:
+                print "%s is not locked." % filepath
+                locked = False
+        except IOError, message:
+            print "File is locked (unable to open in append mode). %s." % \
+                  message
+            locked = True
+        finally:
+            if file_object:
+                file_object.close()
+                print "%s closed." % filepath
+    else:
+        print "%s not found." % filepath
+    return locked
+
+def wait_for_files(filepaths):
+    """Checks if the files are ready.
+
+    For a file to be ready it must exist and can be opened in append
+    mode.
+    """
+    wait_time = 5
+    for filepath in filepaths:
+        filepath = os.path.abspath(filepath)
+        # If the file doesn't exist, wait wait_time seconds and try again
+        # until it's found.
+        while not os.path.exists(filepath):
+            print "%s hasn't arrived. Waiting %s seconds." % \
+                  (filepath, wait_time)
+            time.sleep(wait_time)
+        # If the file exists but locked, wait wait_time seconds and check
+        # again until it's no longer locked by another process.
+        while is_locked(filepath):
+            print "%s is currently in use. Waiting %s seconds." % \
+                  (filepath, wait_time)
+            time.sleep(wait_time)            
+
+

 class Image(DeviceBase, Readable):
    def __init__(self, name, pixel):