Allow inserting empty intervals in the database, and add tests for it.

Previously, we could get empty intervals anyway by having a non-empty
interval and removing a smaller interval around each piece of data.
Turns out that empty intervals are OK and needed in some situations,
so explicitly allow and test for it.

nilmdb/client/client.py

@@ -262,7 +262,7 @@ class StreamInserter(object):
         for line in iter:
             self.insert_line(line)
 
-    def insert_line(self, line):
+    def insert_line(self, line, allow_intermediate = True):
         """Insert a single line of ASCII formatted data.  Line
         must be terminated with '\\n'."""
         if line and (len(line) < 1 or line[-1] != '\n'):
@@ -290,10 +290,7 @@ class StreamInserter(object):
         self._block_data.append(self._line_old)
         self._block_len += len(self._line_old)
 
-        if self._line_new is None:
-            # No next line, so send this as the final block.
-            self._send_block_final()
-        else:
+        if allow_intermediate:
             # Send an intermediate block to the server if needed.
             elapsed = time.time() - self._last_time
             if (self._block_len > self._max_data) or (elapsed > self._max_time):
@@ -321,7 +318,25 @@ class StreamInserter(object):
         If more data is inserted after a finalize(), it will become
         part of a new interval and there may be a gap left in-between."""
         # Special marker tells insert_line that this is the end
-        self.insert_line(None)
+        self.insert_line(None, allow_intermediate = False)
+
+        if self._block_len > 0:
+            # We have data pending, so send the final block
+            self._send_block_final()
+        elif None not in (self._interval_start, self._interval_end):
+            # We have no data, but enough information to create an
+            # empty interval.
+            self._block_start = self._interval_start
+            self._interval_start = None
+            self._send_block_final()
+        else:
+            # No data, and no timestamps to use to create an empty
+            # interval.
+            pass
+
+        # Make sure both timestamps are emptied for future intervals.
+        self._interval_start = None
+        self._interval_end = None
 
     def _send_block_intermediate(self):
         """Send data, when we still have more data to send.

nilmdb/server/server.py

@@ -221,11 +221,6 @@ class Stream(NilmApp):
                                      "error parsing input data: " +
                                      e.message)
 
-        if (not parser.min_timestamp or not parser.max_timestamp or
-            not len(parser.data)):
-            raise cherrypy.HTTPError("400 Bad Request",
-                                     "no data provided")
-
         # Check limits
         start = float(start)
         end = float(end)

tests/test_client.py

@@ -189,7 +189,28 @@ class TestClient(object):
         result = client.stream_insert("/newton/prep", data)
         eq_(result, None)
 
-        # Try forcing a server request with empty data
+        # It's OK to insert an empty interval
+        client.http.put("stream/insert", "", { "path": "/newton/prep",
+                                               "start": 1, "end": 2 })
+        eq_(list(client.stream_intervals("/newton/prep")), [[1, 2]])
+        client.stream_remove("/newton/prep")
+        eq_(list(client.stream_intervals("/newton/prep")), [])
+
+        # Timestamps can be negative too
+        client.http.put("stream/insert", "", { "path": "/newton/prep",
+                                               "start": -2, "end": -1 })
+        eq_(list(client.stream_intervals("/newton/prep")), [[-2, -1]])
+        client.stream_remove("/newton/prep")
+        eq_(list(client.stream_intervals("/newton/prep")), [])
+
+        # Intervals that end at zero shouldn't be any different
+        client.http.put("stream/insert", "", { "path": "/newton/prep",
+                                               "start": -1, "end": 0 })
+        eq_(list(client.stream_intervals("/newton/prep")), [[-1, 0]])
+        client.stream_remove("/newton/prep")
+        eq_(list(client.stream_intervals("/newton/prep")), [])
+
+        # Try forcing a server request with equal start and end
         with assert_raises(ClientError) as e:
             client.http.put("stream/insert", "", { "path": "/newton/prep",
                                                    "start": 0, "end": 0 })
@@ -469,3 +490,89 @@ class TestClient(object):
 
         client.stream_destroy("/context/test")
         client.close()
+
+    def test_client_11_emptyintervals(self):
+        # Empty intervals are ok!  If recording detection events
+        # by inserting rows into the database, we want to be able to
+        # have an interval where no events occurred.  Test them here.
+        client = nilmdb.Client(testurl)
+        client.stream_create("/empty/test", "uint16_1")
+
+        def info():
+            result = []
+            for interval in list(client.stream_intervals("/empty/test")):
+                result.append((client.stream_count("/empty/test", *interval),
+                               interval))
+            return result
+
+        eq_(info(), [])
+
+        # Insert a region with just a few points
+        with client.stream_insert_context("/empty/test") as ctx:
+            ctx.update_start(100)
+            ctx.insert_line("140 1\n")
+            ctx.insert_line("150 1\n")
+            ctx.insert_line("160 1\n")
+            ctx.update_end(200)
+            ctx.finalize()
+
+        eq_(info(), [(3, [100, 200])])
+
+        # Delete chunk, which will leave one data point and two intervals
+        client.stream_remove("/empty/test", 145, 175)
+        eq_(info(), [(1, [100, 145]),
+                     (0, [175, 200])])
+
+        # Try also creating a completely empty interval from scratch,
+        # in a few different ways.
+        client.stream_insert_block("/empty/test", "", 300, 350)
+        client.stream_insert("/empty/test", [], 400, 450)
+        with client.stream_insert_context("/empty/test", 500, 550):
+            pass
+
+        # If enough timestamps aren't provided, empty streams won't be created.
+        client.stream_insert("/empty/test", [])
+        with client.stream_insert_context("/empty/test"):
+            pass
+        client.stream_insert("/empty/test", [], start = 600)
+        with client.stream_insert_context("/empty/test", start = 700):
+            pass
+        client.stream_insert("/empty/test", [], end = 850)
+        with client.stream_insert_context("/empty/test", end = 950):
+            pass
+
+        # Try various things that might cause problems
+        with client.stream_insert_context("/empty/test", 1000, 1050):
+            ctx.finalize() # inserts [1000, 1050]
+            ctx.finalize() # nothing
+            ctx.finalize() # nothing
+            ctx.insert_line("1100 1\n")
+            ctx.finalize() # inserts [1100, 1100.000001]
+            ctx.update_start(1199)
+            ctx.insert_line("1200 1\n")
+            ctx.update_end(1250)
+            ctx.finalize() # inserts [1199, 1250]
+            ctx.update_start(1299)
+            ctx.finalize() # nothing
+            ctx.update_end(1350)
+            ctx.finalize() # nothing
+            ctx.update_start(1400)
+            ctx.update_end(1450)
+            ctx.finalize()
+            # implicit last finalize inserts [1400, 1450]
+
+        # Check everything
+        eq_(info(), [(1, [100, 145]),
+                     (0, [175, 200]),
+                     (0, [300, 350]),
+                     (0, [400, 450]),
+                     (0, [500, 550]),
+                     (0, [1000, 1050]),
+                     (1, [1100, 1100.000001]),
+                     (1, [1199, 1250]),
+                     (0, [1400, 1450]),
+                     ])
+
+        # Clean up
+        client.stream_destroy("/empty/test")
+        client.close()