From 2fd6cf3b5d55665285036f77dc22ca66fe50a837 Mon Sep 17 00:00:00 2001
From: gac-x04sa <gac-x04sa@x04sa-cons-2.psi.ch>
Date: Tue, 26 Feb 2019 14:45:38 +0100
Subject: [PATCH] Script execution

---
 script/device/Image.py | 51 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/script/device/Image.py b/script/device/Image.py
index 0a7e171..a4b5af6 100644
--- a/script/device/Image.py
+++ b/script/device/Image.py
@@ -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):