From 271e46e4adb91da0dddfad4635703a4d90c43119 Mon Sep 17 00:00:00 2001
From: "J.A. de Jong - Redu-Sone B.V., ASCEE V.O.F" <j.a.dejong@ascee.nl>
Date: Thu, 5 Mar 2020 09:43:33 +0100
Subject: [PATCH] Improved shelve API.

---
 lasp/device/lasp_daqconfig.py | 13 ++---
 lasp/lasp_common.py           | 92 +++++++++++++++++++++++------------
 2 files changed, 67 insertions(+), 38 deletions(-)

diff --git a/lasp/device/lasp_daqconfig.py b/lasp/device/lasp_daqconfig.py
index f27cdef..b6981f7 100644
--- a/lasp/device/lasp_daqconfig.py
+++ b/lasp/device/lasp_daqconfig.py
@@ -97,21 +97,18 @@ class DAQConfiguration:
         Returns a list of currently available configurations
         """
         with lasp_shelve() as sh:
-            return sh['daqconfigs'] if 'daqconfigs' in sh.keys() else {}
+            return sh.load('daqconfigs', {})
 
     def saveConfig(self, name):
         with lasp_shelve() as sh:
-            if 'daqconfigs' in sh.keys():
-                cur_configs = sh['daqconfigs']
-            else:
-                cur_configs = {}
+            cur_configs = self.loadConfigs()
             cur_configs[name] = self
-            sh['daqconfigs'] = cur_configs
+            sh.store('daqconfigs', cur_configs)
 
     @staticmethod
     def deleteConfig(name):
         with lasp_shelve() as sh:
-            cur_configs = sh['daqconfigs']
+            cur_configs = DAQConfiguration.loadConfigs()
             del cur_configs[name]
-            sh['daqconfigs'] = cur_configs
+            sh.store('daqconfigs', cur_configs)
 
diff --git a/lasp/lasp_common.py b/lasp/lasp_common.py
index 39b065d..631cedb 100644
--- a/lasp/lasp_common.py
+++ b/lasp/lasp_common.py
@@ -27,44 +27,76 @@ if not os.path.exists(lasp_appdir):
         print('Fatal error: could not create application directory')
         exit(1)
 
-
-class lasp_shelve:
-    refcount = 0
-    shelve = None
+class Shelve:
+    def load(self, key, default_value):
+        """
+        Load data from a given key, if key is not found, returns the
+        default value if key is not found
+        """
+        if key in self.shelve.keys():
+            return self.shelve[key]
+        else:
+            return default_value
 
     def __enter__(self):
-        if lasp_shelve.shelve is None:
-            assert lasp_shelve.refcount == 0
-            lasp_shelve.shelve = shelve.open(
-                os.path.join(lasp_appdir, 'config.shelve'))
-        lasp_shelve.refcount += 1
-        return lasp_shelve.shelve
+        if self.shelve is None:
+            assert self.refcount == 0
+            self.shelve = shelve.open(self.shelve_fn())
+        self.refcount += 1
+        return self
+
+    def store(self, key, val):
+        self.shelve[key] = val
+
+    def deleteIfPresent(self, key):
+        try:
+            del self.shelve[key]
+        except:
+            pass
+
+    def printAllKeys(self):
+        print(list(self.shelve.keys()))
+
+    @property
+    def shelve(self):
+        raise NotImplementedError()
 
     def __exit__(self, type, value, traceback):
-        lasp_shelve.refcount -= 1
-        if lasp_shelve.refcount == 0:
-            lasp_shelve.shelve.close()
-            lasp_shelve.shelve = None
+        self.refcount -= 1
+        if self.refcount == 0:
+            self.shelve.close()
+            self.shelve = None
 
-
-class this_lasp_shelve:
+class lasp_shelve(Shelve):
     refcount = 0
-    shelve = None
+    _shelve = None
 
-    def __enter__(self):
-        if this_lasp_shelve.shelve is None:
-            assert lasp_shelve.refcount == 0
-            node = platform.node()
-            this_lasp_shelve.shelve = shelve.open(
-                os.path.join(lasp_appdir, f'{node}_config.shelve'))
-        this_lasp_shelve.refcount += 1
-        return this_lasp_shelve.shelve
+    @property
+    def shelve(self):
+        return self._shelve
 
-    def __exit__(self, type, value, traceback):
-        this_lasp_shelve.refcount -= 1
-        if this_lasp_shelve.refcount == 0:
-            this_lasp_shelve.shelve.close()
-            this_lasp_shelve.shelve = None
+    @shelve.setter
+    def shelve(self, shelve):
+        self._shelve = shelve
+
+    def shelve_fn(self):
+        return os.path.join(lasp_appdir, 'config.shelve')
+
+class this_lasp_shelve(Shelve):
+    refcount = 0
+    _shelve = None
+
+    @property
+    def shelve(self):
+        return self._shelve
+
+    @shelve.setter
+    def shelve(self, shelve):
+        self._shelve = shelve
+
+    def shelve_fn(self):
+        node = platform.node()
+        return os.path.join(lasp_appdir, f'{node}_config.shelve')
 
 
 # Reference sound pressure level