[GR-22025] Insight script in Python.

PullRequest: graal/6514

tools/CHANGELOG.md

@@ -5,6 +5,7 @@ This changelog summarizes major changes between Truffle Tools versions.
 ## Version 20.2.0
 
 * [GraalVM Insight](docs/Insight-Manual.md#modifying-local-variables) can modify values of local variables
+* Write [GraalVM Insight](docs/Insight-Manual.md#python) scripts in Python
 
 ## Version 20.1.0
 

tools/docs/Insight-Manual.md

@@ -197,6 +197,32 @@ It is necessary to start GraalVM's Ruby launcher with `--polyglot` parameter
 as the `source-tracing.js` script remains written in JavaScript. That's all
 fine - mixing languages has never been a problem for GraalVM!
 
+### Python
+
+It is possible to write your GraalVM Insight scripts in Python. Such insights
+can be applied to programs written in Python or any other language. Here is
+an example of a script that prints out value of variable `n` when a function
+`minusOne` in a `agent-fib.js` file is called:
+
+```python
+def onEnter(ctx, frame):
+    print(f"minusOne {frame.n}")
+
+class Roots:
+    roots = True
+
+    def sourceFilter(self, src):
+        return src.name == "agent-fib.js"
+
+    def rootNameFilter(self, n):
+        return n == "minusOne"
+
+insight.on("enter", onEnter, Roots())
+```
+Apply such script with `js --polyglot --insight=agent.py --experimental-options agent-fib.js`.
+Of course, make sure Python is installed in your GraalVM via the `gu` tool.
+
+
 ### Minimal Overhead
 
 With all the power the **Insight** framework brings, it is fair to ask what's

vm/tests/all/agentscript/agent-python.py

@@ -0,0 +1,17 @@
+print(f"Python: Insight version {insight.version} is launching")
+insight.on("source", lambda env : print(f"Python: observed loading of {env.name}"))
+print("Python: Hooks are ready!")
+
+def onEnter(ctx, frame):
+    print(f"minusOne {frame.n}")
+
+class Roots:
+    roots = True
+
+    def sourceFilter(self, src):
+        return src.name == "agent-fib.js"
+
+    def rootNameFilter(self, n):
+        return n == "minusOne"
+
+insight.on("enter", onEnter, Roots())

vm/tests/all/agentscript/agent-python.test

@@ -0,0 +1,19 @@
+> cat > ${TMP_DIR}/test.py
+< print('Ahoj')
+> graalpython --insight=agent-python.py --experimental-options ${TMP_DIR}/test.py
+Python: Insight version 0.6 is launching
+Python: Hooks are ready!
+Python: observed loading of site.py
+Python: observed loading of _sitebuiltins.py
+Please note: This Python implementation is in the very early stages, and can run little more than basic benchmarks at this point.
+Python: observed loading of test.py
+Ahoj
+> js --polyglot --insight=agent-python.py --experimental-options agent-fib.js
+Python: Insight version 0.6 is launching
+Python: Hooks are ready!
+Python: observed loading of agent-fib.js
+minusOne 4
+minusOne 3
+minusOne 2
+minusOne 2
+Three is the result 3