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Implement process "uncaughtException" event
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This event can be used to overwrite the default exception mechanism which
reports the exception and kills the node process.

See google group post:
http://groups.google.com/group/nodejs/browse_thread/thread/9721dc3a2638446f
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felixge authored and ry committed Nov 14, 2009
1 parent bd6c08a commit 2b252ac
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Showing 3 changed files with 69 additions and 3 deletions.
46 changes: 44 additions & 2 deletions src/node.cc
Original file line number Diff line number Diff line change
Expand Up @@ -524,9 +524,51 @@ static void OnFatalError(const char* location, const char* message) {
exit(1);
}

static int uncaught_exception_counter = 0;

void FatalException(TryCatch &try_catch) {
ReportException(&try_catch);
exit(1);
HandleScope scope;

// Check if uncaught_exception_counter indicates a recursion
if (uncaught_exception_counter > 0) {
ReportException(&try_catch);
exit(1);
}

Local<Value> listeners_v = process->Get(String::NewSymbol("listeners"));
assert(listeners_v->IsFunction());

Local<Function> listeners = Local<Function>::Cast(listeners_v);

Local<String> uncaught_exception = String::NewSymbol("uncaughtException");

Local<Value> argv[1] = { uncaught_exception };
Local<Value> ret = listeners->Call(process, 1, argv);

assert(ret->IsArray());

Local<Array> listener_array = Local<Array>::Cast(ret);

uint32_t length = listener_array->Length();
// Report and exit if process has no "uncaughtException" listener
if (length == 0) {
ReportException(&try_catch);
exit(1);
}

// Otherwise fire the process "uncaughtException" event
Local<Value> emit_v = process->Get(String::NewSymbol("emit"));
assert(emit_v->IsFunction());

Local<Function> emit = Local<Function>::Cast(emit_v);

Local<Value> error = try_catch.Exception();
Local<Value> event_argv[2] = { uncaught_exception, error };

uncaught_exception_counter++;
emit->Call(process, 2, event_argv);
// Decrement so we know if the next exception is a recursion or not
uncaught_exception_counter--;
}

static ev_async eio_watcher;
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1 change: 0 additions & 1 deletion src/node.js
Original file line number Diff line number Diff line change
Expand Up @@ -677,6 +677,5 @@ if (process.ARGV[1].charAt(0) != "/" && !/^http:\/\//.exec(process.ARGV[1])) {
process.mainModule = createModule(".");
var loadPromise = new process.Promise();
process.mainModule.load(process.ARGV[1], loadPromise);
loadPromise.wait();

}()); // end annonymous namespace
25 changes: 25 additions & 0 deletions test/mjsunit/test-exception-handler.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
process.mixin(require("./common"));

var MESSAGE = 'catch me if you can';
var caughtException = false;

process.addListener('uncaughtException', function (e) {
puts("uncaught exception! 1");
assertEquals(MESSAGE, e.message);
caughtException = true;
});

process.addListener('uncaughtException', function (e) {
puts("uncaught exception! 2");
assertEquals(MESSAGE, e.message);
caughtException = true;
});

setTimeout(function() {
throw new Error(MESSAGE);
}, 10);

process.addListener("exit", function () {
puts("exit");
assertTrue(caughtException);
});

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