feat(profiling): stack v2 vm read mode

ddtrace/internal/datadog/profiling/stack_v2/CMakeLists.txt

@@ -41,11 +41,11 @@ endif()
 
 # Add echion
 set(ECHION_COMMIT
-    "6ebe7dddb604aa97e89f072c0fc65c9785e023a0" # https://github.com/P403n1x87/echion/commit/6ebe7dddb604aa97e89f072c0fc65c9785e023a0
+    "07d6dd21b6885231a4529bf101556ba962385112" # https://github.com/taegyunkim/echion/commit/07d6dd21b6885231a4529bf101556ba962385112
     CACHE STRING "Commit hash of echion to use")
 FetchContent_Declare(
     echion
-    GIT_REPOSITORY "https://github.com/P403n1x87/echion.git"
+    GIT_REPOSITORY "https://github.com/taegyunkim/echion.git"
     GIT_TAG ${ECHION_COMMIT})
 FetchContent_GetProperties(echion)
 

ddtrace/internal/datadog/profiling/stack_v2/src/stack_v2.cpp

@@ -191,6 +191,26 @@ stack_v2_set_adaptive_sampling(PyObject* Py_UNUSED(self), PyObject* args)
     Py_RETURN_NONE;
 }
 
+static PyObject*
+stack_v2_set_vm_read_mode(PyObject* self, PyObject* args)
+{
+    (void)self;
+    int new_vm_read_mode;
+    if (!PyArg_ParseTuple(args, "i", &new_vm_read_mode)) {
+        return NULL;
+    }
+
+    if (new_vm_read_mode < 0 || new_vm_read_mode > 2) {
+        new_vm_read_mode = 0;
+    }
+
+    if (!_set_vm_read_mode(new_vm_read_mode)) {
+        Py_RETURN_FALSE;
+    }
+
+    Py_RETURN_TRUE;
+}
+
 static PyMethodDef _stack_v2_methods[] = {
     { "start", reinterpret_cast<PyCFunction>(stack_v2_start), METH_VARARGS | METH_KEYWORDS, "Start the sampler" },
     { "stop", stack_v2_stop, METH_VARARGS, "Stop the sampler" },
@@ -206,6 +226,7 @@ static PyMethodDef _stack_v2_methods[] = {
     { "init_asyncio", stack_v2_init_asyncio, METH_VARARGS, "Initialise asyncio tracking" },
     { "link_tasks", stack_v2_link_tasks, METH_VARARGS, "Link two tasks" },
     { "set_adaptive_sampling", stack_v2_set_adaptive_sampling, METH_VARARGS, "Set adaptive sampling" },
+    { "set_vm_read_mode", stack_v2_set_vm_read_mode, METH_VARARGS, "Set the VM reading mode" },
     { NULL, NULL, 0, NULL }
 };
 

ddtrace/settings/profiling.py

@@ -84,6 +84,33 @@ def _check_for_stack_v2_available():
     return stack_v2_is_available
 
 
+def _check_for_stack_v2_mode(config):
+    if not config.v2_enabled and not _check_for_stack_v2_available():
+        return "disabled"
+
+    mode = config._v2_mode
+    if mode not in ("writev", "process_vm_readv", "sigtrap"):
+        mode = "process_vm_readv"
+
+    # If we're here, then stack v2 has been imported by _check_for_stack_v2_available, so this will probably succeed
+    try:
+        from ddtrace.internal.datadog.profiling import stack_v2
+    except Exception:
+        return "disabled"
+
+    if "process_vm_readv" == mode and stack_v2.set_vm_read_mode(1):
+        return "process_vm_readv"
+    elif "sigtrap" == mode and stack_v2.set_vm_read_mode(2):
+        return "sigtrap"
+
+    # If we're here, then either the other modes were not specified, or they failed--try writev as a failover
+    if stack_v2.set_vm_read_mode(0):
+        return "writev"
+
+    # Boohoo, we failed
+    return "disabled"
+
+
 def _is_libdd_required(config):
     # This function consolidates the logic for force-enabling the libdd uploader.  Otherwise this will get enabled in
     # a bunch of separate places and it'll be tough to manage.
@@ -341,6 +368,15 @@ class ProfilingConfigStack(DDConfig):
     # V2 can't be enabled if stack collection is disabled or if pre-requisites are not met
     v2_enabled = DDConfig.d(bool, lambda c: _check_for_stack_v2_available() and c._v2_enabled and c.enabled)
 
+    _v2_mode = DDConfig.v(
+        str,
+        "v2_mode",
+        default="process_vm_readv",
+        help_type="String",
+        help="The mode to use for the v2 stack profiler. Can be one of 'writev', 'process_vm_readv', or 'sigtrap'.",
+    )
+    v2_mode = DDConfig.d(str, lambda c: _check_for_stack_v2_mode(c))
+
     v2_adaptive_sampling = DDConfig.v(
         bool,
         "v2.adaptive_sampling.enabled",