arolla::CancellationContext

This is a refactoring of the recently introduced `arolla::EvaluationContext::CancellationChecker`.

The key changes are as follows:

 * The context stores the status after a computation has been canceled.
   Motivation: This allows sharing the context between multiple aggregation accumulators, so that all of them can be cancelled at once.

 * The rate-limiting logic has been implemented in the base class.
   Motivation: The compiler can inline it => reduce the overhead.

Benchmarks:
  name                            cpu/op
  BM_CancellationContext_10ms_16  1.60ns ± 4%
  BM_CancellationContext_10ms_4   2.48ns ± 2%
  BM_CancellationContext_10ms_1   5.63ns ± 1%
  BM_CancellationContext_10ms_0   11.4ns ± 1%
PiperOrigin-RevId: 720239473
Change-Id: I05acded6eeb45cf19c7eed3f151487351f010f59

Author: apronchenkov

py/koladata/expr/py_expr_eval.cc

@@ -35,7 +35,7 @@
 #include "koladata/operators/arolla_bridge.h"
 #include "py/arolla/abc/py_aux_binding_policy.h"
 #include "py/arolla/abc/py_cached_eval.h"
-#include "py/arolla/abc/py_cancellation_checker.h"
+#include "py/arolla/abc/py_cancellation_context.h"
 #include "py/arolla/abc/py_expr.h"
 #include "py/arolla/abc/py_operator.h"
 #include "py/arolla/abc/py_qvalue.h"
@@ -62,7 +62,7 @@ using ::arolla::python::AuxBindingPolicyPtr;
 using ::arolla::python::DCheckPyGIL;
 using ::arolla::python::InvokeOpWithCompilationCache;
 using ::arolla::python::ParseArgPyOperator;
-using ::arolla::python::PyCancellationChecker;
+using ::arolla::python::PyCancellationContext;
 using ::arolla::python::QValueOrExpr;
 using ::arolla::python::ReleasePyGIL;
 using ::arolla::python::SetPyErrFromStatus;
@@ -116,9 +116,9 @@ absl::Nullable<PyObject*> PyEvalExpr(PyObject* /*self*/, PyObject** py_args,
 
     // Set up a mechanism to check if the computation has been interrupted by
     // the Python interpreter.
-    PyCancellationChecker cancellation_checker;
+    PyCancellationContext cancellation_context;
     koladata::expr::EvalOptions eval_options{
-        .cancellation_checker = &cancellation_checker,
+        .cancellation_context = &cancellation_context,
     };
     result_or_error = koladata::expr::EvalExprWithCompilationCache(
         expr, input_qvalues, {}, eval_options);