the thing actually works pretty good now

TODO.md

@@ -8,5 +8,27 @@
 - [ ] per-file stats
 - [ ] per-peer stats
 
+- [ ] slow peers cause slowness in the end, need the "end of game" algorithm
+  - [ ] will require implementing cancel message
+
 someday:
-- [ ] cancellation
+- [ ] cancellation from the client-side for the lib (i.e. stop the torrent manager)
+
+
+# concurrency
+it's fucked up now, so need to rethink.
+
+Sequencing:
+- when the peer sends bitfield
+  - update its bitfield
+  - this can only happen at the start. But it can also NOT happen at all (if the peer wants to download)
+    - so we actually cannot use it as a trigger to start the "uploader" of it (where we upload to it)
+  - however both this and "have" we can use as a trigger to start the "downloader" part of it
+- when the peer sends "interested"
+- when the peer sends "have"
+  - update its bitfield
+
+"peer downloader":
+- if started, means there was some initial interest
+- if we are unchoked:
+  - fetch new pieces forever from the queue, send requests