Single threaded alternative processor

.pre-commit-config.yaml

@@ -16,7 +16,7 @@ repos:
         args: [--safe, --line-length=100, --preview]
     -   id: black-jupyter
         args: [--safe, --line-length=100, --preview]
-        language_version: python3.9
+        language_version: python3
 
 -   repo: https://github.com/pycqa/docformatter
     rev: v1.7.5

strax/__init__.py

@@ -20,6 +20,7 @@
 
 from .mailbox import *
 from .processor import *
+from .processors import *
 from .context import *
 from .run_selection import *
 from .corrections import *

strax/chunk.py

@@ -420,3 +420,44 @@ def _update_subruns_in_chunk(chunks):
             else:
                 subruns[subrun_id] = subrun_start_end
     return subruns
+
+
+@export
+class Rechunker:
+    """Helper class for rechunking.
+
+    Send in chunks via receive, which returns either None (no chunk to send) or a chunk to send.
+
+    Don't forget a final call to .flush() to get any final data out!
+
+    """
+
+    def __init__(self, rechunk=False, run_id=None):
+        self.rechunk = rechunk
+        self.is_superrun = run_id and run_id.startswith("_") and not run_id.startswith("__")
+        self.run_id = run_id
+
+        self.cache = None
+
+    def receive(self, chunk):
+        if self.is_superrun:
+            chunk = strax.transform_chunk_to_superrun_chunk(self.run_id, chunk)
+        if not self.rechunk:
+            # We aren't rechunking
+            return chunk
+        if self.cache:
+            # We have an old chunk, so we need to concatenate
+            chunk = strax.Chunk.concatenate([self.cache, chunk])
+        if chunk.data.nbytes >= chunk.target_size_mb * 1e6:
+            # Enough data to send a new chunk!
+            self.cache = None
+            return chunk
+        else:
+            # Not enough data yet, so we cache the chunk
+            self.cache = chunk
+            return None
+
+    def flush(self):
+        result = self.cache
+        self.cache = None
+        return result

strax/context.py

@@ -191,7 +191,11 @@ class Context:
     _run_defaults_cache: dict
     storage: ty.List[strax.StorageFrontend]
 
-    def __init__(self, storage=None, config=None, register=None, register_all=None, **kwargs):
+    processors: ty.Mapping[str, strax.BaseProcessor]
+
+    def __init__(
+        self, storage=None, config=None, register=None, register_all=None, processors=None, **kwargs
+    ):
         """Create a strax context.
 
         :param storage: Storage front-ends to use. Can be:
@@ -202,7 +206,9 @@ def __init__(self, storage=None, config=None, register=None, register_all=None,
             applied to plugins
         :param register: plugin class or list of plugin classes to register
         :param register_all: module for which all plugin classes defined in it
-            will be registered.
+           will be registered.
+        :param processors: A mapping of processor names to classes to use for
+            data processing.
         Any additional kwargs are considered Context-specific options; see
         Context.takes_config.
 
@@ -226,12 +232,32 @@ def __init__(self, storage=None, config=None, register=None, register_all=None,
         if register is not None:
             self.register(register)
 
+        if processors is None:
+            processors = strax.PROCESSORS
+
+        if isinstance(processors, str):
+            processors = [processors]
+
+        if isinstance(processors, (list, tuple)):
+            ps = {}
+            for processor in processors:
+                if isinstance(processor, str) and processor in strax.PROCESSORS:
+                    ps[processor] = strax.PROCESSORS[processor]
+                elif isinstance(processor, strax.BaseProcessor):
+                    ps[processor.__name__] = processor
+                else:
+                    raise ValueError(f"Unknown processor {processor}")
+            processors = ps
+
+        self.processors = processors
+
     def new_context(
         self,
         storage=tuple(),
         config=None,
         register=None,
         register_all=None,
+        processors=None,
         replace=False,
         **kwargs,
     ):
@@ -255,7 +281,7 @@ def new_context(
             config = strax.combine_configs(self.config, config, mode="update")
             kwargs = strax.combine_configs(self.context_config, kwargs, mode="update")
 
-        new_c = Context(storage=storage, config=config, **kwargs)
+        new_c = Context(storage=storage, config=config, processors=processors, **kwargs)
         if not replace:
             new_c._plugin_class_registry = self._plugin_class_registry.copy()
         new_c.register_all(register_all)
@@ -1434,7 +1460,7 @@ def to_absolute_time_range(
     def get_iter(
         self,
         run_id: str,
-        targets: ty.Union[ty.Tuple[str], ty.List[str]],
+        targets,
         save=tuple(),
         max_workers=None,
         time_range=None,
@@ -1449,6 +1475,7 @@ def get_iter(
         progress_bar=True,
         multi_run_progress_bar=True,
         _chunk_number=None,
+        processor=None,
         **kwargs,
     ) -> ty.Iterator[strax.Chunk]:
         """Compute target for run_id and iterate over results.
@@ -1516,8 +1543,17 @@ def get_iter(
             if k.startswith("_temp"):
                 del self._plugin_class_registry[k]
 
+        if processor is None:
+            processor = list(self.processors)[0]
+
+        if isinstance(processor, str):
+            processor = self.processors[processor]
+
+        if not hasattr(processor, "iter"):
+            raise ValueError("Processors must implement a iter methed.")
+
         seen_a_chunk = False
-        generator = strax.ThreadedMailboxProcessor(
+        generator = processor(
             components,
             max_workers=max_workers,
             allow_shm=self.context_config["allow_shm"],
@@ -2542,8 +2578,7 @@ def add_method(cls, f):
 :param multi_run_progress_bar: Display a progress bar for loading multiple runs
 """
 
-get_docs = (
-    """
+get_docs = """
 :param run_id: run id to get
 :param targets: list/tuple of strings of data type names to get
 :param ignore_errors: Return the data for the runs that successfully loaded, even if some runs
@@ -2563,9 +2598,10 @@ def add_method(cls, f):
 :param run_id_as_bytes: Boolean if true uses byte string instead of an
     unicode string added to a multi-run array. This can save a lot of
     memory when loading many runs.
+:param processor: Name of the processor to use. If not specified, the
+    first processor from the context's processor list is used.
 """
-    + select_docs
-)
+get_docs += select_docs
 
 for attr in dir(Context):
     attr_val = getattr(Context, attr)