Add WASI stubs for mmap_read/mmap_write/recv_exact and fix accel logging

The _singlestoredb_accel C extension ifdef'd out the mmap and socket
functions for __wasi__ builds, but registry.py imports all four symbols
(call_function_accel, mmap_read, mmap_write, recv_exact) in a single
try block. The missing exports caused the entire import to fail,
silently falling back to the pure Python call_function loop.

Add #else stubs that raise NotImplementedError if called, so the
symbols are importable and call_function_accel works in WASM. Also
capture the accel import error and log it in initialize() for future
diagnostics.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kesmit13

accel.c

@@ -5449,6 +5449,23 @@ static PyObject *accel_recv_exact(PyObject *self, PyObject *args) {
     free(buf);
     return result;
 }
+#else /* __wasi__ stubs — importable but raise NotImplementedError if called */
+
+static PyObject *accel_mmap_read(PyObject *self, PyObject *args) {
+    PyErr_SetString(PyExc_NotImplementedError, "mmap_read is not available in WASM");
+    return NULL;
+}
+
+static PyObject *accel_mmap_write(PyObject *self, PyObject *args) {
+    PyErr_SetString(PyExc_NotImplementedError, "mmap_write is not available in WASM");
+    return NULL;
+}
+
+static PyObject *accel_recv_exact(PyObject *self, PyObject *args) {
+    PyErr_SetString(PyExc_NotImplementedError, "recv_exact is not available in WASM");
+    return NULL;
+}
+
 #endif /* !__wasi__ */
 
 static PyMethodDef PyMySQLAccelMethods[] = {
@@ -5458,11 +5475,9 @@ static PyMethodDef PyMySQLAccelMethods[] = {
     {"dump_rowdat_1_numpy", (PyCFunction)dump_rowdat_1_numpy, METH_VARARGS | METH_KEYWORDS, "ROWDAT_1 formatter for external functions which takes numpy.arrays"},
     {"load_rowdat_1_numpy", (PyCFunction)load_rowdat_1_numpy, METH_VARARGS | METH_KEYWORDS, "ROWDAT_1 parser for external functions which creates numpy.arrays"},
     {"call_function_accel", (PyCFunction)call_function_accel, METH_VARARGS | METH_KEYWORDS, "Combined load/call/dump for UDF function calls"},
-#ifndef __wasi__
     {"mmap_read", (PyCFunction)accel_mmap_read, METH_VARARGS, "mmap read: maps fd, copies data, unmaps"},
     {"mmap_write", (PyCFunction)accel_mmap_write, METH_VARARGS, "mmap write: ftruncate+lseek+write in one call"},
     {"recv_exact", (PyCFunction)accel_recv_exact, METH_VARARGS, "Receive exactly N bytes from a socket fd"},
-#endif
     {NULL, NULL, 0, NULL}
 };
 

singlestoredb/functions/ext/collocated/registry.py

@@ -27,6 +27,7 @@
 from singlestoredb.functions.signature import get_signature
 from singlestoredb.mysql.constants import FIELD_TYPE as ft
 
+_accel_error: Optional[str] = None
 try:
     from _singlestoredb_accel import call_function_accel as _call_function_accel
     from _singlestoredb_accel import mmap_read as _mmap_read
@@ -36,6 +37,7 @@
     logging.getLogger(__name__).info('_singlestoredb_accel loaded successfully')
 except Exception as e:
     _has_accel = False
+    _accel_error = str(e)
     _mmap_read = None
     _mmap_write = None
     _recv_exact = None

singlestoredb/functions/ext/collocated/wasm.py

@@ -8,6 +8,7 @@
 import logging
 import traceback
 
+from .registry import _accel_error
 from .registry import _has_accel
 from .registry import call_function
 from .registry import describe_functions_json
@@ -30,6 +31,11 @@ def initialize(self) -> None:
             logger.info('Using accelerated C call_function_accel loop')
         else:
             logger.info('Using pure Python call_function loop')
+            if _accel_error:
+                logger.warning(
+                    '_singlestoredb_accel failed to load: %s',
+                    _accel_error,
+                )
         _registry.initialize()
 
     def call_function(self, name: str, input_data: bytes) -> bytes: