experiment with using ctypes to wrap libusdt.so

depends on chrisa/libusdt#9

Author: nshalman

.gitignore

@@ -1,2 +1,4 @@
 *.so
+*.pyc
+core
 build/

Makefile

@@ -1,15 +1,16 @@
+ctypes: dtrace-ctypes.py libusdt.so
+	sudo dtrace -Zqn ':::func{printf("%s\n",copyinstr(arg0));}' -c ./dtrace-ctypes.py
+
+libusdt.so: libusdt/libusdt.a
+	gcc -g -shared -o $@ -Wl,--whole-archive $<
+
 test: dtrace.so test.py
-	@echo
-	@echo Run the following in another shell:
-	@echo "sudo dtrace -qn ':::testname{printf(\"%s\\\\n\",copyinstr(arg0));}'"
-	@echo
-	@sleep 2
-	python test.py
+	sudo dtrace -Zqn ':::testname{printf("%s\n",copyinstr(arg0));}' -c ./test.py
 
 dtrace.so: libusdt/libusdt.a dtrace.c setup.py
 	rm -rf dtrace.so build/
 	python setup.py build
-	cp build/lib*/dtrace.so .
+	mv build/lib*/*.so .
 
 libusdt/libusdt.a:
 	git submodule init

dtrace-ctypes.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+
+from ctypes import *
+import time
+
+_libusdt = cdll.LoadLibrary("./libusdt.so")
+
+usdt_create_provider = _libusdt.usdt_create_provider
+usdt_create_provider.argtypes = [c_char_p, c_char_p]
+
+usdt_create_probe = _libusdt.usdt_create_probe
+usdt_create_probe.argtypes = [c_char_p, c_char_p, c_int, c_void_p]
+
+usdt_provider_add_probe = _libusdt.usdt_provider_add_probe
+usdt_provider_enable = _libusdt.usdt_provider_enable
+usdt_fire_probedef = _libusdt.usdt_fire_probedef
+
+class Probe():
+	def __init__(self, name, func, arg_desc):
+		self.length = len(arg_desc)
+		args = (c_char_p * self.length)()
+		for i in range(self.length):
+			args[i] = arg_desc[i]
+		self.probedef = usdt_create_probe(name, func, self.length, args)
+
+	def fire(self, args):
+		if len(args) == self.length:
+			c_args = (c_void_p * self.length)()
+			for i in range(self.length):
+				c_args[i] = cast(args[i], c_void_p)
+			usdt_fire_probedef(self.probedef, self.length, c_args)
+
+class Provider():
+	provider = None
+	probes = []
+	def __init__(self, provider="python-dtrace", module="default_module"):
+		self.provider = usdt_create_provider(provider, module)
+
+	def add_probe(self, probe):
+		self.probes.append(probe)
+		usdt_provider_add_probe(self.provider, probe.probedef)
+
+	def enable(self):
+		usdt_provider_enable(self.provider)
+
+	def __del__(self):
+		pass
+
+def main():
+	test_prov = Provider("provname", "provmod")
+	test_probe = Probe("probename", "func", ["char *"])
+	test_prov.add_probe(test_probe)
+	test_prov.enable()
+
+	test_probe.fire(["Hello World"])
+
+if __name__ == "__main__":
+	main()

test.py

@@ -28,7 +28,7 @@ def timeout2():
 def timeout3():
 	print timeout1() + " " + timeout2()
 
-while True:
+for i in range(2):
 	timeout3()
 	dtrace.fire("Hello dtrace")
 	time.sleep(1)