From 7b1c0939bda468fdc5e4533eda79683fa92ac793 Mon Sep 17 00:00:00 2001
From: Tyler Goodlet <jgbt@protonmail.com>
Date: Sun, 1 May 2022 12:40:51 -0400
Subject: [PATCH] Add first-draft `trimeter` based concurrent ohlc history
 fetching

---
 piker/data/feed.py | 131 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 111 insertions(+), 20 deletions(-)

diff --git a/piker/data/feed.py b/piker/data/feed.py
index b00cf70e..88bf8810 100644
--- a/piker/data/feed.py
+++ b/piker/data/feed.py
@@ -35,6 +35,7 @@ from typing import (
 import trio
 from trio.abc import ReceiveChannel
 from trio_typing import TaskStatus
+import trimeter
 import tractor
 from pydantic import BaseModel
 import pendulum
@@ -263,32 +264,66 @@ async def start_backfill(
         # let caller unblock and deliver latest history frame
         task_status.started((shm, start_dt, end_dt, bf_done))
 
+        times = array['time']
+        step_size_s = (
+            pendulum.from_timestamp(times[-1]) -
+            pendulum.from_timestamp(times[-2])
+        ).seconds
+        frame_step_s = (end_dt - start_dt).seconds
+
         if last_tsdb_dt is None:
             # maybe a better default (they don't seem to define epoch?!)
-            last_tsdb_dt = pendulum.now().subtract(days=1)
+
+            # based on the sample step size load a certain amount
+            # history
+            if step_size_s == 1:
+                last_tsdb_dt = pendulum.now().subtract(weeks=2)
+
+            elif step_size_s == 60:
+                last_tsdb_dt = pendulum.now().subtract(years=2)
+
+            else:
+                raise ValueError(
+                    '`piker` only needs to support 1m and 1s sampling '
+                    'but ur api is trying to deliver a longer '
+                    f'timeframe of {step_size_s} ' 'seconds.. so ye, dun '
+                    'do dat bruh.'
+                )
+
+        hist_period = pendulum.period(
+            start_dt.subtract(seconds=step_size_s),
+            last_tsdb_dt,
+        )
+        end_dts = list(hist_period.range('seconds', frame_step_s))
 
         # pull new history frames until we hit latest
         # already in the tsdb or a max count.
-        # mx_fills = 16
         count = 0
-        # while True:
-        while (
-            end_dt > last_tsdb_dt
-            # and count < mx_fills
-        ):
+        frames = {}
+
+        async def get_ohlc_frame(
+            input_end_dt: datetime,
+
+        ) -> np.ndarray:
+
+            nonlocal count
             count += 1
             try:
-                array, start_dt, end_dt = await hist(end_dt=start_dt)
+                array, start_dt, end_dt = await hist(end_dt=input_end_dt)
+                # if input_end_dt.timestamp() == end_dts[0].timestamp():
+                #     await tractor.breakpoint()
 
             except NoData:
                 # decrement by the diff in time last delivered.
                 end_dt = start_dt.subtract(seconds=(end_dt - start_dt).seconds)
-                continue
+                log.warning('no data for range {(end_dt - start_dt)} ?!?')
+                # continue
 
             except DataUnavailable:
                 # broker is being a bish and we can't pull
                 # any more..
-                break
+                log.warning('backend halted on data deliver !?!?')
+                # break
 
             to_push = diff_history(
                 array,
@@ -302,18 +337,74 @@ async def start_backfill(
             print(f"PULLING {count}")
             log.info(f'Pushing {to_push.size} to shm!')
 
-            if to_push.size < 1:
-                break
+            frames[input_end_dt.timestamp()] = (to_push, start_dt, end_dt)
 
-            # bail on shm allocation overrun
-            try:
-                shm.push(to_push, prepend=True)
-            except ValueError:
-                await tractor.breakpoint()
-                break
+            return to_push, start_dt, end_dt
 
-            for delay_s in sampler.subscribers:
-                await broadcast(delay_s)
+            # if to_push.size < 1:
+            #     print('UHHH SIZE <1 BREAKING!?')
+            #     break
+
+        rate = erlangs = 5
+        async with trimeter.amap(
+
+            get_ohlc_frame,
+            end_dts,
+
+            capture_outcome=True,
+            include_value=True,
+            max_at_once=erlangs,
+            max_per_second=rate,
+
+        ) as outcomes:
+
+            # Then iterate over the return values, as they become available
+            # (i.e., not necessarily in the original order)
+            async for input_end_dt, outcome in outcomes:
+                try:
+                    out = outcome.unwrap()
+                except Exception:
+                    log.exception('uhh trimeter bail')
+                    raise
+                else:
+                    to_push, start_dt, end_dt = out
+
+                # pipeline-style pull frames until we need to wait for
+                # the next in order to arrive.
+                i = end_dts.index(input_end_dt)
+                print(f'latest end_dt {end_dt} found at index {i}')
+
+                for epoch in reversed(sorted(frames)):
+                    start = shm.array['time'][0]
+
+                    # we don't yet have the next frame to push
+                    # so break back to the async request loop.
+                    diff = epoch - start
+                    if abs(diff) > step_size_s:
+                        if len(frames) > 20:
+                            log.warning(
+                                f'there appears to be a history gap of {diff}?'
+                            )
+                            # from pprint import pprint
+                            # await tractor.breakpoint()
+                        else:
+                            break
+
+                    to_push, start_dt, end_dt = frames.pop(epoch)
+                    print(f'pushing frame ending at {end_dt}')
+
+                    if not len(to_push):
+                        break
+
+                    # bail on shm allocation overrun
+                    try:
+                        shm.push(to_push, prepend=True)
+                    except ValueError:
+                        await tractor.breakpoint()
+                        break
+
+                    for delay_s in sampler.subscribers:
+                        await broadcast(delay_s)
 
         bf_done.set()
         # update start index to include all tsdb history