Sync shm mod with dev version in `tractor`, drop buffer sizing vars, require `size: int` to all allocators

piker/data/_sharedmem.py

@@ -37,15 +37,6 @@ from ._source import def_iohlcv_fields
 from .types import Struct
 
 
-# how  much is probably dependent on lifestyle
-_secs_in_day = int(60 * 60 * 24)
-# we try for a buncha times, but only on a run-every-other-day kinda week.
-_days_worth = 16
-_default_size = _days_worth * _secs_in_day
-# where to start the new data append index
-_rt_buffer_start = int((_days_worth - 1) * _secs_in_day)
-
-
 def cuckoff_mantracker():
     '''
     Disable all ``multiprocessing``` "resource tracking" machinery since
@@ -70,7 +61,6 @@ def cuckoff_mantracker():
     mantracker._resource_tracker = ManTracker()
     mantracker.register = mantracker._resource_tracker.register
     mantracker.ensure_running = mantracker._resource_tracker.ensure_running
-    # ensure_running = mantracker._resource_tracker.ensure_running
     mantracker.unregister = mantracker._resource_tracker.unregister
     mantracker.getfd = mantracker._resource_tracker.getfd
 
@@ -442,10 +432,10 @@ class ShmArray:
 
 
 def open_shm_array(
-
-    key: Optional[str] = None,
-    size: int = _default_size,  # see above
-    dtype: Optional[np.dtype] = None,
+    size: int,
+    key: str | None = None,
+    dtype: np.dtype | None = None,
+    append_start_index: int | None = None,
     readonly: bool = False,
 
 ) -> ShmArray:
@@ -510,10 +500,13 @@ def open_shm_array(
     # ``ShmArray._start.value: int = 0`` and the yet-to-be written
     # real-time section will start at ``ShmArray.index: int``.
 
-    # this sets the index to 3/4 of the length of the buffer
-    # leaving a "days worth of second samples" for the real-time
-    # section.
-    last.value = first.value = _rt_buffer_start
+    # this sets the index to nearly 2/3rds into the the length of
+    # the buffer leaving at least a "days worth of second samples"
+    # for the real-time section.
+    if append_start_index is None:
+        append_start_index = round(size * 0.616)
+
+    last.value = first.value = append_start_index
 
     shmarr = ShmArray(
         array,
@@ -527,7 +520,6 @@ def open_shm_array(
 
     # "unlink" created shm on process teardown by
     # pushing teardown calls onto actor context stack
-
     stack = tractor.current_actor().lifetime_stack
     stack.callback(shmarr.close)
     stack.callback(shmarr.destroy)
@@ -622,7 +614,10 @@ def attach_shm_array(
 
 def maybe_open_shm_array(
     key: str,
-    dtype: Optional[np.dtype] = None,
+    size: int,
+    dtype: np.dtype | None = None,
+    append_start_index: int | None = None,
+    readonly: bool = False,
     **kwargs,
 
 ) -> tuple[ShmArray, bool]:
@@ -643,11 +638,16 @@ def maybe_open_shm_array(
     use ``attach_shm_array``.
 
     '''
-    size = kwargs.pop('size', _default_size)
     try:
         # see if we already know this key
         token = _known_tokens[key]
-        return attach_shm_array(token=token, **kwargs), False
+        return (
+            attach_shm_array(
+                token=token,
+                readonly=readonly,
+            ),
+            False,
+        )
     except KeyError:
         log.debug(f"Could not find {key} in shms cache")
         if dtype:
@@ -666,8 +666,16 @@ def maybe_open_shm_array(
         # Attempt to open a block and expect
         # to fail if a block has been allocated
         # on the OS by someone else.
-        return open_shm_array(key=key, dtype=dtype, **kwargs), True
-
+        return (
+            open_shm_array(
+                key=key,
+                size=size,
+                dtype=dtype,
+                append_start_index=append_start_index,
+                readonly=readonly,
+            ),
+            True,
+        )
 
 def try_read(
     array: np.ndarray