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New section: design principles
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</ul> | </ul> | ||
= Design Principles for <b>js::dbg2</b> = | |||
<ul> | |||
<li><b>js::dbg2 must support remote debugging.</b> Using a protocol | |||
resembling the [http://code.google.com/p/v8/wiki/DebuggerProtocol V8 | |||
debugger protocol], js::dbg2 should allow the debugger's user interface to | |||
run in a separate process, perhaps even on a separate machine, from the | |||
debuggee. This allows us to debug on mobile devices and worker threads, and | |||
increases the segregation of debugger and debuggee. | |||
<li><b>js::dbg2 will support cross-thread debugging via remote | |||
debugging.</b> The "server" for the remote protocol will be lightweight | |||
enough that each thread will be able to run its own instance. The debugger | |||
user interface will then simply be responsible for being a client to | |||
multiple debug servers at once. All cross-thread interaction will be | |||
mediated by the remote protocol, greatly simplifying js::dbg2's | |||
implementation. | |||
<p>(Note that some operations are inherently cross-thread: enumerating | |||
currently running threads; thread creation notifications; the initial | |||
attachment of the debugger to a thread. But once a thread has been attached | |||
to, all subsequent communication is via the remote protocol.)</p> | |||
<li><b>js::dbg2 must operate at the JavaScript source language level.</b> | |||
SpiderMonkey's current debugging interfaces (jsdbgapi and jsd) are built | |||
around the specifics of the bytecode engine. While that interface can be | |||
supported in JägerMonkey and TraceMonkey as well, this is a needless | |||
mismatch in abstraction level. Supporting js::dbg2 should require | |||
JägerMonkey and TraceMonkey to relate the state of the running compiled | |||
program directly to the original JavaScript program --- not to the state of | |||
imaginary bytecode, which is then related to the original JavaScript. | |||
</ul> | |||
= Event Handlers and Spheres = | = Event Handlers and Spheres = | ||