Implement "cylc set" command.

    Long, messy dev history squashed flat like a bug.

changes.d/5658.feat.md

@@ -0,0 +1 @@
+New "cylc set" command for setting task prerequisites and outputs.

cylc/flow/data_store_mgr.py

@@ -2185,8 +2185,9 @@ def update_workflow(self, reloaded=False):
             w_delta.n_edge_distance = self.n_edge_distance
             delta_set = True
 
-        if self.schd.pool.main_pool:
-            pool_points = set(self.schd.pool.main_pool)
+        if self.schd.pool.active_tasks:
+            pool_points = set(self.schd.pool.active_tasks)
+
             oldest_point = str(min(pool_points))
             if w_data.oldest_active_cycle_point != oldest_point:
                 w_delta.oldest_active_cycle_point = oldest_point

cylc/flow/etc/cylc

@@ -2,7 +2,7 @@
 
 # THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
 # Copyright (C) NIWA & British Crown (Met Office) & Contributors.
-# 
+#
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
 # the Free Software Foundation, either version 3 of the License, or

cylc/flow/flow_mgr.py

@@ -20,50 +20,164 @@
 import datetime
 
 from cylc.flow import LOG
+from cylc.flow.exceptions import InputError
 
 
 if TYPE_CHECKING:
     from cylc.flow.workflow_db_mgr import WorkflowDatabaseManager
 
-
 FlowNums = Set[int]
 # Flow constants
 FLOW_ALL = "all"
 FLOW_NEW = "new"
 FLOW_NONE = "none"
 
+# For flow-related CLI options:
+ERR_OPT_FLOW_VAL = "Flow values must be an integer, or 'all', 'new', or 'none'"
+ERR_OPT_FLOW_INT = "Multiple flow options must all be integer valued"
+ERR_OPT_FLOW_WAIT = (
+    f"--wait is not compatible with --flow={FLOW_NEW} or --flow={FLOW_NONE}"
+)
+
+
+def add_flow_opts(parser):
+    parser.add_option(
+        "--flow", action="append", dest="flow", metavar="FLOW",
+        help=f'Assign new tasks to all active flows ("{FLOW_ALL}");'
+             f' no flow ("{FLOW_NONE}"); a new flow ("{FLOW_NEW}");'
+             f' or a specific flow (e.g. "2"). The default is "{FLOW_ALL}".'
+             ' Specific flow numbers can be new or existing.'
+             ' Reuse the option to assign multiple flow numbers.'
+    )
+
+    parser.add_option(
+        "--meta", metavar="DESCRIPTION", action="store",
+        dest="flow_descr", default=None,
+        help=f"description of new flow (with --flow={FLOW_NEW})."
+    )
+
+    parser.add_option(
+        "--wait", action="store_true", default=False, dest="flow_wait",
+        help="Wait for merge with current active flows before flowing on."
+             " Note you can use 'cylc set --pre=all' to unset a flow-wait."
+    )
+
+
+def validate_flow_opts(options):
+    """Check validity of flow-related CLI options."""
+    if options.flow is None:
+        # Default to all active flows
+        options.flow = [FLOW_ALL]
+
+    for val in options.flow:
+        val = val.strip()
+        if val in [FLOW_NONE, FLOW_NEW, FLOW_ALL]:
+            if len(options.flow) != 1:
+                raise InputError(ERR_OPT_FLOW_INT)
+        else:
+            try:
+                int(val)
+            except ValueError:
+                raise InputError(ERR_OPT_FLOW_VAL.format(val))
+
+    if options.flow_wait and options.flow[0] in [FLOW_NEW, FLOW_NONE]:
+        raise InputError(ERR_OPT_FLOW_WAIT)
+
+
+def stringify_flow_nums(flow_nums: Set[int], full: bool = False) -> str:
+    """Return a string representation of a set of flow numbers
+
+    Return:
+    - "none" for no flow
+    - "" for the original flow (flows only matter if there are several)
+    - otherwise e.g. "(flow=1,2,3)"
+
+    Examples:
+        >>> stringify_flow_nums({})
+        '(flows=none)'
+
+        >>> stringify_flow_nums({1})
+        ''
+
+        >>> stringify_flow_nums({1}, True)
+        '(flows=1)'
+
+        >>> stringify_flow_nums({1,2,3})
+        '(flows=1,2,3)'
+
+    """
+    if not full and flow_nums == {1}:
+        return ""
+    else:
+        return (
+            "(flows="
+            f"{','.join(str(i) for i in flow_nums) or 'none'}"
+            ")"
+        )
+
 
 class FlowMgr:
     """Logic to manage flow counter and flow metadata."""
 
-    def __init__(self, db_mgr: "WorkflowDatabaseManager") -> None:
+    def __init__(
+        self,
+        db_mgr: "WorkflowDatabaseManager",
+        utc: bool = True
+    ) -> None:
         """Initialise the flow manager."""
         self.db_mgr = db_mgr
         self.flows: Dict[int, Dict[str, str]] = {}
         self.counter: int = 0
+        self._timezone = datetime.timezone.utc if utc else None
 
-    def get_new_flow(self, description: Optional[str] = None) -> int:
-        """Increment flow counter, record flow metadata."""
-        self.counter += 1
-        # record start time to nearest second
-        now = datetime.datetime.now()
-        now_sec: str = str(
-            now - datetime.timedelta(microseconds=now.microsecond))
-        description = description or "no description"
-        self.flows[self.counter] = {
-            "description": description,
-            "start_time": now_sec
-        }
-        LOG.info(
-            f"New flow: {self.counter} "
-            f"({description}) "
-            f"{now_sec}"
-        )
-        self.db_mgr.put_insert_workflow_flows(
-            self.counter,
-            self.flows[self.counter]
-        )
-        return self.counter
+    def get_flow_num(
+        self,
+        flow_num: Optional[int] = None,
+        meta: Optional[str] = None
+    ) -> int:
+        """Return a valid flow number, and record a new flow if necessary.
+
+        If asked for a new flow:
+           - increment the automatic counter until we find an unused number
+
+        If given a flow number:
+           - record a new flow if the number is unused
+           - else return it, as an existing flow number.
+
+        The metadata string is only used if it is a new flow.
+
+        """
+        if flow_num is None:
+            self.counter += 1
+            while self.counter in self.flows:
+                # Skip manually-created out-of-sequence flows.
+                self.counter += 1
+            flow_num = self.counter
+
+        if flow_num in self.flows:
+            if meta is not None:
+                LOG.warning(
+                    f'Ignoring flow metadata "{meta}":'
+                    f' {flow_num} is not a new flow'
+                )
+        else:
+            # Record a new flow.
+            now_sec = datetime.datetime.now(tz=self._timezone).isoformat(
+                timespec="seconds"
+            )
+            meta = meta or "no description"
+            self.flows[flow_num] = {
+                "description": meta,
+                "start_time": now_sec
+            }
+            LOG.info(
+                f"New flow: {flow_num} ({meta}) {now_sec}"
+            )
+            self.db_mgr.put_insert_workflow_flows(
+                flow_num,
+                self.flows[flow_num]
+            )
+        return flow_num
 
     def load_from_db(self, flow_nums: FlowNums) -> None:
         """Load flow data for scheduler restart.

cylc/flow/graph_parser.py

@@ -33,6 +33,7 @@
 from cylc.flow.task_id import TaskID
 from cylc.flow.task_trigger import TaskTrigger
 from cylc.flow.task_outputs import (
+    TASK_OUTPUT_EXPIRED,
     TASK_OUTPUT_SUCCEEDED,
     TASK_OUTPUT_STARTED,
     TASK_OUTPUT_FAILED,
@@ -41,6 +42,8 @@
     TASK_OUTPUT_SUBMIT_FAILED
 )
 from cylc.flow.task_qualifiers import (
+    QUAL_FAM_EXPIRE_ALL,
+    QUAL_FAM_EXPIRE_ANY,
     QUAL_FAM_SUCCEED_ALL,
     QUAL_FAM_SUCCEED_ANY,
     QUAL_FAM_FAIL_ALL,
@@ -124,6 +127,8 @@ class GraphParser:
     # E.g. QUAL_FAM_START_ALL: (TASK_OUTPUT_STARTED, True) simply maps
     #   "FAM:start-all" to "MEMBER:started" and "-all" (all members).
     fam_to_mem_trigger_map: Dict[str, Tuple[str, bool]] = {
+        QUAL_FAM_EXPIRE_ALL: (TASK_OUTPUT_EXPIRED, True),
+        QUAL_FAM_EXPIRE_ANY: (TASK_OUTPUT_EXPIRED, False),
         QUAL_FAM_START_ALL: (TASK_OUTPUT_STARTED, True),
         QUAL_FAM_START_ANY: (TASK_OUTPUT_STARTED, False),
         QUAL_FAM_SUCCEED_ALL: (TASK_OUTPUT_SUCCEEDED, True),
@@ -140,6 +145,8 @@ class GraphParser:
 
     # Map family pseudo triggers to affected member outputs.
     fam_to_mem_output_map: Dict[str, List[str]] = {
+        QUAL_FAM_EXPIRE_ANY: [TASK_OUTPUT_EXPIRED],
+        QUAL_FAM_EXPIRE_ALL: [TASK_OUTPUT_EXPIRED],
         QUAL_FAM_START_ANY: [TASK_OUTPUT_STARTED],
         QUAL_FAM_START_ALL: [TASK_OUTPUT_STARTED],
         QUAL_FAM_SUCCEED_ANY: [TASK_OUTPUT_SUCCEEDED],
@@ -738,6 +745,10 @@ def _set_output_opt(
         if suicide:
             return
 
+        if output == TASK_OUTPUT_EXPIRED and not optional:
+            raise GraphParseError(
+                f"Expired-output {name}:{output} must be optional")
+
         if output == TASK_OUTPUT_FINISHED:
             # Interpret :finish pseudo-output
             if optional:

cylc/flow/id_match.py

@@ -76,7 +76,7 @@
 
 
 def filter_ids(
-    pools: 'List[Pool]',
+    pool: 'Pool',
     ids: 'Iterable[str]',
     *,
     warn: 'bool' = True,
@@ -145,28 +145,25 @@ def filter_ids(
             if tokens.get(lowest_token.value):
                 break
 
-        # This needs to be a set to avoid getting two copies of matched tasks
-        # in cycle points that appear in both pools:
         cycles = set()
         tasks = []
 
         # filter by cycle
         if lowest_token == IDTokens.Cycle:
             cycle = tokens[IDTokens.Cycle.value]
             cycle_sel = tokens.get(IDTokens.Cycle.value + '_sel') or '*'
-            for pool in pools:
-                for icycle, itasks in pool.items():
-                    if not itasks:
-                        continue
-                    if not point_match(icycle, cycle, pattern_match):
-                        continue
-                    if cycle_sel == '*':
+            for icycle, itasks in pool.items():
+                if not itasks:
+                    continue
+                if not point_match(icycle, cycle, pattern_match):
+                    continue
+                if cycle_sel == '*':
+                    cycles.add(icycle)
+                    continue
+                for itask in itasks.values():
+                    if match(itask.state.status, cycle_sel):
                         cycles.add(icycle)
-                        continue
-                    for itask in itasks.values():
-                        if match(itask.state.status, cycle_sel):
-                            cycles.add(icycle)
-                            break
+                        break
 
         # filter by task
         elif lowest_token == IDTokens.Task:   # noqa SIM106
@@ -176,36 +173,35 @@ def filter_ids(
             task = tokens[IDTokens.Task.value]
             task_sel_raw = tokens.get(IDTokens.Task.value + '_sel')
             task_sel = task_sel_raw or '*'
-            for pool in pools:
-                for icycle, itasks in pool.items():
-                    if not point_match(icycle, cycle, pattern_match):
-                        continue
-                    for itask in itasks.values():
-                        if (
-                            # check cycle selector
+            for icycle, itasks in pool.items():
+                if not point_match(icycle, cycle, pattern_match):
+                    continue
+                for itask in itasks.values():
+                    if (
+                        # check cycle selector
+                        (
                             (
-                                (
-                                    # disable cycle_sel if not defined if
-                                    # pattern matching is turned off
-                                    pattern_match is False
-                                    and cycle_sel_raw is None
-                                )
-                                or match(itask.state.status, cycle_sel)
+                                # disable cycle_sel if not defined if
+                                # pattern matching is turned off
+                                pattern_match is False
+                                and cycle_sel_raw is None
                             )
-                            # check namespace name
-                            and itask.name_match(task, match_func=match)
-                            # check task selector
-                            and (
-                                (
-                                    # disable task_sel if not defined if
-                                    # pattern matching is turned off
-                                    pattern_match is False
-                                    and task_sel_raw is None
-                                )
-                                or match(itask.state.status, task_sel)
+                            or match(itask.state.status, cycle_sel)
+                        )
+                        # check namespace name
+                        and itask.name_match(task, match_func=match)
+                        # check task selector
+                        and (
+                            (
+                                # disable task_sel if not defined if
+                                # pattern matching is turned off
+                                pattern_match is False
+                                and task_sel_raw is None
                             )
-                        ):
-                            tasks.append(itask)
+                            or match(itask.state.status, task_sel)
+                        )
+                    ):
+                        tasks.append(itask)
 
         else:
             raise NotImplementedError
@@ -226,10 +222,9 @@ def filter_ids(
         })
         ret = _cycles
     elif out == IDTokens.Task:
-        for pool in pools:
-            for icycle in _cycles:
-                if icycle in pool:
-                    _tasks.extend(pool[icycle].values())
+        for icycle in _cycles:
+            if icycle in pool:
+                _tasks.extend(pool[icycle].values())
         ret = _tasks
     return ret, _not_matched