Profiling suggested that on Linux sometimes over 10% of CPU time was
being spent inside the systemtap probe entry points in the binding
layer, even when the process was not actively being traced with the
`stap` tool.
That's why this commit makes it possible to use the *_ENABLED() macros
and bail out early when we're not being traced, reducing the overhead
of unused probes to (almost) zero.
Said macros were already being generated by `dtrace -h` but were not
usable because they rely on external definitions. To remedy that, we
now generate the accompanying object files with `dtrace -G`.
This commit includes a change to libuv that has been landed upstream in
commit joyent/libuv@3c172ea.
* Change calls to String::New() and String::NewSymbol() to their
respective one-byte, two-byte and UTF-8 counterparts.
* Add a FIXED_ONE_BYTE_STRING macro that takes a string literal and
turns it into a v8::Local<v8::String>.
* Add helper functions that make v8::String::NewFromOneByte() easier to
work with. Said function expects a `const uint8_t*` but almost every
call site deals with `const char*` or `const unsigned char*`. Helps
us avoid doing reinterpret_casts all over the place.
* Code that handles file system paths keeps using UTF-8 for backwards
compatibility reasons. At least now the use of UTF-8 is explicit.
* Remove v8::String::NewSymbol() entirely. Almost all call sites were
effectively minor de-optimizations. If you create a string only once,
there is no point in making it a symbol. If you are create the same
string repeatedly, it should probably be cached in a persistent
handle.
This is a big commit that touches just about every file in the src/
directory. The V8 API has changed in significant ways. The most
important changes are:
* Binding functions take a const v8::FunctionCallbackInfo<T>& argument
rather than a const v8::Arguments& argument.
* Binding functions return void rather than v8::Handle<v8::Value>. The
return value is returned with the args.GetReturnValue().Set() family
of functions.
* v8::Persistent<T> no longer derives from v8::Handle<T> and no longer
allows you to directly dereference the object that the persistent
handle points to. This means that the common pattern of caching
oft-used JS values in a persistent handle no longer quite works,
you first need to reconstruct a v8::Local<T> from the persistent
handle with the Local<T>::New(isolate, persistent) factory method.
A handful of (internal) convenience classes and functions have been
added to make dealing with the new API a little easier.
The most visible one is node::Cached<T>, which wraps a v8::Persistent<T>
with some template sugar. It can hold arbitrary types but so far it's
exclusively used for v8::Strings (which was by far the most commonly
cached handle type.)
OSX and other DTrace implementations don't support dereferencing
structs in probes. To accomodate that pass members from the struct as
arguments so that DTrace is useful on those systems.
OSX and other DTrace implementations don't support dereferencing
structs in probes. To accomodate that pass members from the struct as
arguments so that DTrace is useful on those systems.
All compile time warnings about using deprecated APIs have been
suppressed by updating node's API. Though there are still many function
calls that can accept Isolate, and still need to be updated.
node_isolate had to be added as an extern variable in node.h and
node_object_wrap.h
Also a couple small fixes for Error handling.
Before v8 3.16.6 the error stack message was lazily written when it was
needed, which allowed you to change the message after instantiation.
Then the stack would be written with the new message the first time it
was accessed. Though that has changed. Now it creates the stack message
on instantiation. So setting a different message afterwards won't be
displayed.
This is not a complete fix for the problem. Getting error without any
message isn't very useful.
This commit enables ETW events to be fired on Windows for existing
DTrace probes. ETW instrumentation is enabled by default. It
is possible to build node.exe without ETW instrumentation by
using --without-etw option with configure script.
Fedor Indutny
Ben Noordhuis
Timothy J Fontaine
Dave Pacheco
Trevor Norris
Jan Wynholds
Igor Zinkovsky
ssuda
Bert Belder
Ryan Dahl