1 files changed, 97 insertions, 0 deletions
diff --git a/psutil/arch/windows/wmi.c b/psutil/arch/windows/wmi.c
new file mode 100644
index 00000000..18f0d5c7
--- /dev/null
+++ b/psutil/arch/windows/wmi.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2009, Giampaolo Rodola'. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <Python.h>
+#include <windows.h>
+#include <pdh.h>
+
+#include "../../_psutil_common.h"
+
+
+// We use an exponentially weighted moving average, just like Unix systems do
+// https://en.wikipedia.org/wiki/Load_(computing)#Unix-style_load_calculation
+// This constant serves as the damping factor.
+#define LOADAVG_FACTOR_1F 0.9200444146293232478931553241
+// The time interval in seconds between taking load counts
+#define SAMPLING_INTERVAL 5
+
+
+double load_1m = 0;
+
+
+VOID CALLBACK LoadCallback(PVOID hCounter) {
+    PDH_FMT_COUNTERVALUE displayValue;
+    double currentLoad = displayValue.doubleValue;
+    double newLoad;
+
+    PdhGetFormattedCounterValue(
+        (PDH_HCOUNTER)hCounter, PDH_FMT_DOUBLE, 0, &displayValue);
+
+    newLoad = load_1m * LOADAVG_FACTOR_1F + currentLoad * \
+        (1.0 - LOADAVG_FACTOR_1F);
+    load_1m = newLoad;
+}
+
+
+PyObject *
+psutil_init_loadcounter(PyObject *self, PyObject *args) {
+    WCHAR *szCounterPath = L"\\System\\Processor Queue Length";
+    PDH_STATUS s;
+    BOOL ret;
+    HQUERY hQuery;
+    HCOUNTER hCounter;
+    HANDLE event;
+    HANDLE waitHandle;
+
+    if ((PdhOpenQueryW(NULL, 0, &hQuery)) != ERROR_SUCCESS)
+        goto error;
+
+    s = PdhAddEnglishCounterW(hQuery, szCounterPath, 0, &hCounter);
+    if (s != ERROR_SUCCESS)
+        goto error;
+
+    event = CreateEventW(NULL, FALSE, FALSE, L"LoadUpdateEvent");
+    if (event == NULL) {
+        PyErr_SetFromWindowsErr(GetLastError());
+        return NULL;
+    }
+
+    s = PdhCollectQueryDataEx(hQuery, SAMPLING_INTERVAL, event);
+    if (s != ERROR_SUCCESS)
+        goto error;
+
+    ret = RegisterWaitForSingleObject(
+        &waitHandle,
+        event,
+        (WAITORTIMERCALLBACK)LoadCallback,
+        (PVOID)
+        hCounter,
+        INFINITE,
+        WT_EXECUTEDEFAULT);
+
+    if (ret == 0) {
+        PyErr_SetFromWindowsErr(GetLastError());
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+
+error:
+    PyErr_SetExcFromWindowsErr(PyExc_OSError, 0);
+    return NULL;
+}
+
+
+/*
+ * Gets the 1 minute load average (processor queue length) for the system.
+ * InitializeLoadCounter must be called before this function to engage the
+ * mechanism that records load values.
+ */
+PyObject *
+psutil_get_loadcounter(PyObject *self, PyObject *args) {
+    PyObject* load = PyFloat_FromDouble(load_1m);
+    return load;
+}