Add a basic example #165

zofrex · 2015-07-01T02:38:21Z

I am sure this still needs work, but it's a starting point for a basic example - #134. Credit to jdm, Ms2ger, and mbrubeck for helping me get this far!

Things that are missing compared to the SpiderMonkey documentation:

JS_InitStandardClasses
Error handling (see #164)

zofrex · 2015-07-01T02:51:03Z

This example works and doesn't crash, but with SM assertions on, it fails:

$ cargo run --features debugmozjs --example callback
Assertion failure: cx->runtime()->requestDepth || cx->runtime()->isHeapBusy(), at /Users/zofrex/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/jscntxt.cpp:1144
An unknown error occurred

michaelwu · 2015-07-01T03:05:59Z

Add in a JSAutoRequest

zofrex · 2015-07-01T03:20:58Z

Thanks! Getting a different one now, can't figure this one out...

Assertion failure: clasp->trace == JS_GlobalObjectTraceHook, at /Users/zofrex/.cargo/git/checkouts/mozjs-06d7f04b6dbb8a8e/master/mozjs/js/src/vm/GlobalObject.cpp:243

Going to take a break and revisit this tomorrow.

michaelwu · 2015-07-01T04:10:45Z

It wants JS_GlobalObjectTraceHook in trace, but you have trace set to None. Note that you'll need to use the mangled version of that.

Ms2ger · 2015-07-01T07:17:52Z

Don't forget the MPL2 header.

zofrex · 2015-07-01T12:48:44Z

Thanks! Bit horrible that you can't use the JS_GlobalObjectTraceHook wrapper :(

Almost there, it's now failing an assert at the end of evaluate_script in rust.rs:

Assertion failure: mStatementDone, at ../../dist/include/mozilla/GuardObjects.h:100

Looks like it's complaining about a guard object used as temporary, but I can't find one...

Ms2ger · 2015-07-01T14:25:21Z

Rooted::new(context, global).handle() looks highly suspicious

jdm · 2015-07-01T14:30:35Z

https://github.com/servo/rust-mozjs/pull/165/files#diff-490a245ae6cc96c180d8cb9a9a8eaaa6R50 looks wrong to me - the RootedObject will only be a temporary that will live as long as that statement, and the Handle will point to invalid memory.

michaelwu · 2015-07-01T19:05:40Z

You're making a handle in the puts functions. In general, you can't make manually make handles unless you know exactly what you're doing.

I don't think I can help with the guard object issue without more information to figure out what object the guard object is embedded in.

zofrex · 2015-07-01T21:08:40Z

I believe I've fixed both the rooting / handle issues. Michael - I don't know how to figure out which object the guard object is embedded in. I tried adding a breakpoint on guard object creation but that was far too noisy to be useful.

michaelwu · 2015-07-01T21:12:11Z

A stack on that assertion would help.

zofrex · 2015-07-01T21:23:22Z

https://gist.github.com/zofrex/a7832f69c06b08e0135e

michaelwu · 2015-07-01T21:54:49Z

This might be an issue with the C++ part of the glue being built without debug/debugmozjs enabled. Try clobbering target/ and building from scratch.

zofrex · 2015-07-01T22:16:09Z

That works! (And also explains why this code worked without crashing on my other machine...)

Alright, the code compiles and runs with no errors, even with debugmozjs enabled. What's next?

jdm · 2015-07-01T22:47:54Z

examples/callback.rs

+        let global_root = Rooted::new(context, global);
+        let global = global_root.handle();
+        let _ac = JSAutoCompartment::new(context, global.get());
+        JS_DefineFunction(context, global, CString::new("puts").unwrap().as_ptr(), Some(puts), 1, 0);


Instead of CString, this could probably be b"puts\0".as_ptr()

jdm · 2015-07-01T22:48:00Z

examples/callback.rs

+    let args = CallArgs::from_vp(vp, argc);
+
+    if args.argc_ != 1 {
+        JS_ReportError(context, CString::new("puts() requires exactly 1 argument").unwrap().as_ptr());


Same as above.

zofrex · 2015-07-02T09:58:21Z

It needs a as *const i8 or as *const libc::c_char if I do it the b"something.as_ptr() way. I have no opinion on which is less ugly.

jdm · 2015-07-02T12:04:55Z

I'd go with c_char.


        Add a basic example

jdm · 2015-07-02T19:02:42Z

@bors-servo: r+

bors-servo · 2015-07-02T19:02:43Z

📌 Commit 4044555 has been approved by jdm

bors-servo · 2015-07-02T19:02:44Z

⌛ Testing commit 4044555 with merge b600fee...


        Auto merge of #165 - zofrex:add-example, r=jdm

Add a basic example I am sure this still needs work, but it's a starting point for a basic example - #134. Credit to jdm, Ms2ger, and mbrubeck for helping me get this far! Things that are missing compared to the SpiderMonkey documentation: * JS_InitStandardClasses * Error handling (see #164)

bors-servo · 2015-07-02T19:09:06Z

💔 Test failed - cargo-mac


        Merge pull request #165 from zofrex/add-example

Add a basic example; r=jdm

Ms2ger mentioned this pull request Jul 1, 2015

Handle should not be able to outlive its Rooted #166

Closed

jdm reviewed Jul 1, 2015
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examples/callback.rs Outdated

let args = CallArgs::from_vp(vp, argc);

if args.argc_ != 1 {

JS_ReportError(context, CString::new("puts() requires exactly 1 argument").unwrap().as_ptr());

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jdm Jul 1, 2015
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Same as above.

zofrex force-pushed the zofrex:add-example branch from 6775401 to 4044555 Jul 2, 2015

Add a basic example

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4044555

Ms2ger added a commit that referenced this pull request Jul 2, 2015

Merge pull request #165 from zofrex/add-example

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Add a basic example; r=jdm

Ms2ger merged commit a76ddc6 into servo:master Jul 2, 2015
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zofrex mentioned this pull request Jul 3, 2015

Create a sample applications #134

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servo / rust-mozjs

Add a basic example #165

Add a basic example #165

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