Add Gas Metering for pywasm3

platforms/python/examples/coremark.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+
+import wasm3
+import os, time
+
+scriptpath = os.path.dirname(os.path.realpath(__file__))
+wasm_fn = os.path.join(scriptpath, "./wasm/coremark-minimal.wasm")
+
+print("Initializing Wasm3 engine...")
+
+def clock_ms():
+    return int(round(time.time() * 1000))
+
+env = wasm3.Environment()
+rt = env.new_runtime(4096)
+
+with open(wasm_fn, "rb") as f:
+    mod = env.parse_module(f.read())
+    rt.load(mod)
+    mod.link_function("env", "clock_ms",    "i()",  clock_ms)
+
+# Gas metering will only apply to metered (pre-instrumented) modules
+mod.gasLimit = 200_000_000
+
+wasm_run = rt.find_function("run")
+
+print("Running CoreMark 1.0...")
+res = wasm_run()
+
+if res > 1:
+    print(f"Result: {res:.3f}")
+else:
+    print("Error")
+
+if mod.gasUsed:
+    print(f"Gas used: {mod.gasUsed}")
+

platforms/python/m3module.c

@@ -20,6 +20,9 @@ typedef struct {
     PyObject_HEAD
     m3_environment *env;
     IM3Module m;
+    //bool is_gas_metered;
+    int64_t total_gas;
+    int64_t current_gas;
 } m3_module;
 
 typedef struct {
@@ -117,6 +120,7 @@ M3_Environment_parse_module(m3_environment *env, PyObject *bytes)
     Py_INCREF(env);
     self->env = env;
     self->m = m;
+    self->total_gas = self->current_gas = 0;
     return self;
 }
 
@@ -200,6 +204,40 @@ Module_name(m3_module *self, void * closure)
     return PyUnicode_FromString(m3_GetModuleName(self->m));
 }
 
+static int
+Module_setGasLimit(m3_module *self, PyObject *value, void * closure)
+{
+    self->total_gas = PyFloat_AsDouble(value)*10000.0;
+    self->current_gas = self->total_gas;
+    return 0;
+}
+
+static PyObject *
+Module_getGasLimit(m3_module *self, void * closure)
+{
+    return PyFloat_FromDouble((double)(self->total_gas)/10000.0);
+}
+
+static PyObject *
+Module_getGasUsed(m3_module *self, void * closure)
+{
+    return PyFloat_FromDouble((double)(self->total_gas - self->current_gas)/10000.0);
+}
+
+m3ApiRawFunction(metering_usegas)
+{
+    m3ApiGetArg     (int32_t, gas)
+
+    m3_module *mod = (m3_module *)(_ctx->userdata);
+
+    mod->current_gas -= gas;
+
+    if (UNLIKELY(mod->current_gas < 0)) {
+        m3ApiTrap("[trap] Out of gas");
+    }
+    m3ApiSuccess();
+}
+
 m3ApiRawFunction(CallImport)
 {
     PyObject *pFunc = (PyObject *)(_ctx->userdata);
@@ -266,12 +304,23 @@ M3_Module_link_function(m3_module *self, PyObject *args)
     if (err && err != m3Err_functionLookupFailed) {
         return formatError(PyExc_RuntimeError, m3_GetModuleRuntime(self->m), err);
     }
+    
+    err = m3_LinkRawFunctionEx (self->m, "metering", "usegas", "v(i)", &metering_usegas, self);
+    /*if (!err) {
+        self->is_gas_metered = true;
+    }*/
+    if (err && err != m3Err_functionLookupFailed) {
+        return formatError(PyExc_RuntimeError, m3_GetModuleRuntime(self->m), err);
+    }
+
     Py_INCREF(pFunc);
     Py_RETURN_NONE;
 }
 
 static PyGetSetDef M3_Module_properties[] = {
-    {"name", (getter) Module_name, NULL, "module name", NULL},
+    {"name",        (getter) Module_name, NULL, "module name", NULL},
+    {"gasLimit",    (getter) Module_getGasLimit, (setter) Module_setGasLimit, "gas limit for metered modules", NULL},
+    {"gasUsed",     (getter) Module_getGasUsed, NULL, "gas used", NULL},
     {0},
 };
 

platforms/python/setup.py

@@ -21,7 +21,7 @@ setup(
 
     ext_modules=[
         Extension('wasm3', sources=SOURCES, include_dirs=['m3'],
-        extra_compile_args=['-g', '-O3'])
+        extra_compile_args=['-g0', '-O3', '-DDEBUG', '-DNASSERTS'])
     ],
 
     classifiers  = [