PyV8 debugger not properly handling break events

While playing with PyV8 debugger I identified an issue. As you can easily 
realize from the attached test code, the command line argument is used to 
enable/disable the Debugger onMessage method. If the code is executed with 
onMessage method disabled, nothing happens after the BeforeCompile/AfterCompile 
events. This should be a bug because a break event is generated but not handled 
by the Debugger class methods.


buffer@alnitak ~ $ python DebuggerTest.py 0
BeforeCompile event: 
{"seq":0,"type":"event","event":"beforeCompile","success":true,"body":{"script":

{"handle":1,"type":"script","id":17,"lineOffset":0,"columnOffset":0,"lineCount":
14,"sourceStart":"\nfunction my_func(t)\n{\n\tvar s = \"foo\";\n\tvar i = 
0;\n\n\tfor (i = 0; i < 3; i++) 
{\n\t","sourceLength":120,"scriptType":2,"compilationType":0,"context":{"ref":0}
,"text":" (lines: 
14)"}},"refs":[{"handle":0,"type":"context","text":"#<ContextMirror>"}],"running
":true}
AfterCompile event: 
{"seq":2,"type":"event","event":"afterCompile","success":true,"body":{"script":{
"handle":1,"type":"script","id":17,"lineOffset":0,"columnOffset":0,"lineCount":1
4,"sourceStart":"\nfunction my_func(t)\n{\n\tvar s = \"foo\";\n\tvar i = 
0;\n\n\tfor (i = 0; i < 3; i++) 
{\n\t","sourceLength":120,"scriptType":2,"compilationType":0,"context":{"ref":0}
,"text":" (lines: 
14)"}},"refs":[{"handle":0,"type":"context","text":"#<ContextMirror>"}],"running
":true}
[hanging here]


Taking a look at what happens when the onMessage is enabled, we can see that 
the break event is properly generated so it seems not to be handled as stated 
before.


buffer@alnitak ~ $ python DebuggerTest.py 1
BeforeCompile event: 
{"seq":0,"type":"event","event":"beforeCompile","success":true,"body":{"script":
{"handle":1,"type":"script","id":17,"lineOffset":0,"columnOffset":0,"lineCount":
14,"sourceStart":"\nfunction my_func(t)\n{\n\tvar s = \"foo\";\n\tvar i = 
0;\n\n\tfor (i = 0; i < 3; i++) 
{\n\t","sourceLength":120,"scriptType":2,"compilationType":0,"context":{"ref":0}
,"text":" (lines: 
14)"}},"refs":[{"handle":0,"type":"context","text":"#<ContextMirror>"}],"running
":true}
Debug message: {u'body': {u'script': {u'columnOffset': 0, u'handle': 1, 
u'compilationType': 0, u'text': u' (lines: 14)', u'sourceLength': 120, 
u'sourceStart': u'\nfunction my_func(t)\n{\n\tvar s = "foo";\n\tvar i = 
0;\n\n\tfor (i = 0; i < 3; i++) {\n\t', u'lineCount': 14, u'scriptType': 2, 
u'lineOffset': 0, u'context': {u'ref': 0}, u'type': u'script', u'id': 17}}, 
u'seq': 1, u'success': True, u'refs': [{u'type': u'context', u'handle': 0, 
u'text': u'#<ContextMirror>'}], u'running': True, u'type': u'event', u'event': 
u'afterCompile'}
AfterCompile event: 
{"seq":2,"type":"event","event":"afterCompile","success":true,"body":{"script":{
"handle":1,"type":"script","id":17,"lineOffset":0,"columnOffset":0,"lineCount":1
4,"sourceStart":"\nfunction my_func(t)\n{\n\tvar s = \"foo\";\n\tvar i = 
0;\n\n\tfor (i = 0; i < 3; i++) 
{\n\t","sourceLength":120,"scriptType":2,"compilationType":0,"context":{"ref":0}
,"text":" (lines: 
14)"}},"refs":[{"handle":0,"type":"context","text":"#<ContextMirror>"}],"running
":true}
Debug message: {u'body': {u'invocationText': u'[anonymous]()', u'script': 
{u'lineCount': 14, u'columnOffset': 0, u'id': 17, u'lineOffset': 0, u'name': 
u''}, u'sourceLineText': u'', u'sourceColumn': 0, u'sourceLine': 0}, u'type': 
u'event', u'event': u'break', u'seq': 3}
[hanging here]

Regards,
Angelo

Original issue reported on code.google.com by angelo.d...@gmail.com on 13 Jun 2011 at 2:11

Attachments:

• DebuggerTest.py

Start with the attached DebuggerTest.py and run it with command-line arguments 0 and 1 to reproduce the different behavior around BeforeCompile and AfterCompile. Trace the Debugger onMessage path and the Debugger class methods for the generated break event. Done means the break event is handled when onMessage is disabled and the test no longer hangs.