added package structure

bstrd/bscache.py

@@ -0,0 +1,103 @@
+from time import sleep
+from bsread import source, dispatcher
+from .bsvar import BSVar
+from .prodthread import ProdThread
+
+
+class BSCache:
+
+    def __init__(self):
+        self.channels = {}
+        self.data = None
+        self.pt = ProdThread(self.run)
+
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        self.pt.start()
+        self.data = data = self.pt.queue.get()
+        return data
+
+
+    def run(self, queue, running):
+        channels = self.channels.keys()
+        configs  = self.channels.values()
+        with source(channels=configs, receive_timeout=-1) as src:
+            while running.is_set():
+                msg = src.receive()
+                data = repack(channels, msg)
+                if data:
+                    queue.put(data)
+
+
+    def stop(self):
+        self.pt.stop()
+
+
+    def get_var(self, name, modulo=None, offset=None):
+        if name is not "pid" and not name in self.channels:
+            if not is_available(name):
+                raise ValueError(f"channel {name} is not available")
+            cfg = make_channel_config(name, modulo, offset)
+            self.update_source(name, cfg)
+        return BSVar(name, self)
+
+
+    def update_source(self, name, cfg):
+        self.pt.stop()
+        print("add channel", name)
+        self.channels[name] = cfg
+        self.pt.start()
+
+        while self.data is None or name not in self.data:
+            print("dropping data that is missing new channel:", name)
+            next(self)
+
+
+
+
+
+def is_available(name):
+    available = get_available_channels()
+    return name in available
+
+def get_available_channels():
+    channels = dispatcher.get_current_channels()
+    return set(ch["name"] for ch in channels)
+
+
+
+def make_channel_config(name, modulo, offset):
+    res = {}
+    if modulo is not None:
+        res["modulo"] = modulo
+    if offset is not None:
+        res["offset"] = offset
+    if not res:
+        return name
+    res["name"] = name
+    return res
+
+
+
+def repack(channels, message):
+    data     = message.data.data
+    pulse_id = message.data.pulse_id
+
+    res = {n: data[n].value for n in channels}
+#    res = {k: v for k, v in res.items() if v is not None}
+
+    #TODO: should this be a ValueError?
+    if any(v is None for v in res.values()):
+        return None
+
+    if not res:
+        return None
+
+    res["pid"] = pulse_id
+    return res
+
+
+