reimplement backlog query again

[loctrkd.git] / gps303 / evstore.py

diff --git a/gps303/evstore.py b/gps303/evstore.py
index 70a3ac6618bec9bd67f53ff7fa9a30a6d92484c4..a52a64c1e5ad468676349ad299e6fb14b174eceb 100644 (file)
--- a/gps303/evstore.py
+++ b/gps303/evstore.py
@@ -1,8 +1,8 @@
 """ sqlite event store """
 
-from sqlite3 import connect
+from sqlite3 import connect, OperationalError
 
-__all__ = "initdb", "stow"
+__all__ = "fetch", "initdb", "stow"
 
 DB = None
 
@@ -10,6 +10,7 @@ SCHEMA = """create table if not exists events (
     tstamp real not null,
     imei text,
     peeraddr text not null,
+    is_incoming int not null default TRUE,
     proto int not null,
     packet blob
 )"""
@@ -18,7 +19,13 @@ SCHEMA = """create table if not exists events (
 def initdb(dbname):
     global DB
     DB = connect(dbname)
-    DB.execute(SCHEMA)
+    try:
+        DB.execute(
+            """alter table events add column
+                is_incoming int not null default TRUE"""
+        )
+    except OperationalError:
+        DB.execute(SCHEMA)
 
 
 def stow(**kwargs):
@@ -26,6 +33,7 @@ def stow(**kwargs):
     parms = {
         k: kwargs[k] if k in kwargs else v
         for k, v in (
+            ("is_incoming", True),
             ("peeraddr", None),
             ("when", 0.0),
             ("imei", None),
@@ -36,10 +44,30 @@ def stow(**kwargs):
     assert len(kwargs) <= len(parms)
     DB.execute(
         """insert or ignore into events
-                (tstamp, imei, peeraddr, proto, packet)
+                (tstamp, imei, peeraddr, proto, packet, is_incoming)
                 values
-                (:when, :imei, :peeraddr, :proto, :packet)
+                (:when, :imei, :peeraddr, :proto, :packet, :is_incoming)
         """,
         parms,
     )
     DB.commit()
+
+
+def fetch(imei, matchlist, backlog):
+    # matchlist is a list of tuples (is_incoming, proto)
+    # returns a list of tuples (is_incoming, timestamp, packet)
+    assert DB is not None
+    selector = " or ".join(
+        (f"(is_incoming = ? and proto = ?)" for _ in range(len(matchlist)))
+    )
+    cur = DB.cursor()
+    cur.execute(
+        f"""select is_incoming, tstamp, packet from events
+                    where ({selector}) and imei = ?
+                    order by tstamp desc limit ?""",
+        tuple(item for sublist in matchlist for item in sublist)
+        + (imei, backlog),
+    )
+    result = list(cur)
+    cur.close()
+    return list(reversed(result))